diff options
Diffstat (limited to 'arch/x86_64/pre')
72 files changed, 3573 insertions, 0 deletions
diff --git a/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp new file mode 100644 index 0000000..07110c8 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp @@ -0,0 +1,69 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP + +#include "arch/context_switching/interrupt_descriptor_table/idt_flags.hpp" +#include "arch/context_switching/interrupt_descriptor_table/ist_offset.hpp" +#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp" + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + __extension__ typedef __int128 int128_t; + __extension__ typedef unsigned __int128 uint128_t; + + /** + * @brief Defines helper function for all states and the actual data the gate descriptor can have. + */ + struct [[gnu::packed]] gate_descriptor + { + /** + * @brief Default Constructor. + */ + gate_descriptor() = default; + + /** + * @brief Constructor. + * + * @note Created gate descriptor copies the given bytes into these components ending with a 32 bit reserved + * field that has to be used, because the 64-bit gate descriptor needs to be big enough for two 32-bit gate + * descriptor. + * - 16 bit Segment Selector + * - 3 bit Interrupt Stack Table Offset + * - 8 bit Type and Flags + * - 64 bit Offset + * + * @param flags Copies the bits set from the given data into the individual components of a gate + * descriptor. + */ + explicit gate_descriptor(uint128_t flags); + + /** + * @brief Constructor. + * + * @param selector, ist, flags, offset Copies the bits set from the given data into the individual components of + * a gate descriptor. + */ + gate_descriptor(segment_selector selector, ist_offset ist, idt_flags flags, uint64_t offset); + + /** + * @brief Allows to compare the underlying bits of two instances. + * + * @param other Other instance that we want to compare with. + * @return Whether the underlying set bits of both types are the same. + */ + auto operator==(gate_descriptor const & other) const -> bool = default; + + private: + // The order in private variables starts for the first variable being the rightmost bit. + uint16_t _offset_1 = {}; ///< Lower 16 bits of handler function address (0 - 15) + segment_selector _selector = {}; ///< Segment selector (16 - 31) + ist_offset _ist = {}; ///< Interrupt Stack Table offset (32 - 39) + idt_flags _flags = {}; ///< Gate Type and Flags (40 - 47) + uint64_t _offset_2 : 48 = {}; ///< Upper 48 bits of handler function address (48 - 95) + uint32_t : 32; ///< Reserved field used to ensure this struct is 128 bits big (96 - 127) + }; +} // namespace teachos::arch::context_switching::interrupt_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/idt_flags.hpp b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/idt_flags.hpp new file mode 100644 index 0000000..5104c36 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/idt_flags.hpp @@ -0,0 +1,81 @@ + +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IDT_FLAGS_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IDT_FLAGS_HPP + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + /** + * @brief Defines helper function for all states that the access byte field of a segment descriptor can + * have. + */ + struct [[gnu::packed]] idt_flags + { + /** + * @brief Possible set bits in our underlying bits and the meaning when they are set. + */ + enum bitset : uint8_t + { + INTERRUPT_GATE = 0b01110, ///< The actual type of gate segment is a interrupt gate. + TRAP_GATE = 0b01111, ///< The actual type of gate segment is a trap gate. + DESCRIPTOR_LEVEL_KERNEL = + 0U << 5U, ///< Highest privileged level used by the kernel to allow for full access of resources. + DESCRIPTOR_LEVEL_ADMIN = + 1U << 5U, ///< Restricts access to own application and thoose of lower privilege. Should only be used if more + ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended. + DESCRIPTOR_LEVEL_PRIVILEGED_USER = + 2U << 5U, ///< Restricts access to own application and thoose of lower privilege. Should only be used if more + ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended. + DESCRIPTOR_LEVEL_USER = 3U << 5U, ///< Restricts access to only application and their specific memory. + PRESENT = 1U << 7U, ///< Present bit; Allows an entry to refer to a valid segment. + ///< Must be set (1) for any valid segment. + }; + + /** + * @brief Default Constructor. + */ + idt_flags() = default; + + /** + * @brief Constructor. + * + * @param flags Allows to set flags for the access byte field using the unscoped enum contained in this class, used + * to allow for direct integer conversion. This value is saved and can later be used to check whether certain flags + * are enabled or not using contains_flags method. + */ + idt_flags(uint8_t flags); + + /** + * @brief Checks if the given std::bitset is a subset or equivalent to the underlying data. + * + * @note Meaning that all bits that are set in the given std::bitset also have to be set in the underlyng + * data. Any additional bits that are set are not relevant. + * + * @param other Flags that we want to compare against and check if the underlying data has the same bits set. + * @return Whether the given flags are a subset or equivalent with the underlying data. + */ + auto contains_flags(std::bitset<8U> other) const -> bool; + + /** + * @brief Allows to compare the underlying bits of two instances. + * + * @param other Other instance that we want to compare with. + * @return Whether the underlying set bits of both types are the same. + */ + auto operator==(idt_flags const & other) const -> bool = default; + + /** + * @brief Combines all bits that are set in the std::bitset flags with the bits already set in the underlying data. + * + * @param other Additional bits that should be set. + */ + auto operator|=(std::bitset<8U> other) -> void; + + private: + uint8_t _flags = {}; ///< Underlying bits used to read the flags from. + }; +} // namespace teachos::arch::context_switching::interrupt_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IDT_FLAGS_HPP
\ No newline at end of file diff --git a/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp new file mode 100644 index 0000000..b388e0e --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp @@ -0,0 +1,24 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP + +#include "arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + /** + * @brief Updates the IDTR with the created interrupt descriptor table. If it has not been created yet this + * method will create it. + */ + auto update_interrupt_descriptor_table_register() -> void; + + /** + * @brief Creates the interrupt descriptor table, with the minimum required configuration. If this method is called + * more than once, the previously created instance is returned instead. + * + * @return Reference to the created interrupt_descriptor_table. + */ + auto get_or_create_interrupt_descriptor_table() -> interrupt_descriptor_table &; + +} // namespace teachos::arch::context_switching::interrupt_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp new file mode 100644 index 0000000..7fe933b --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp @@ -0,0 +1,40 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP + +#include "arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp" +#include "arch/stl/vector.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + using interrupt_descriptor_table = stl::vector<gate_descriptor>; + + /** + * @brief Represents a pointer to the Interrupt Descriptor Table (IDT). + * + * This structure is used to store the base address and length of the IDT. + */ + struct [[gnu::packed]] interrupt_descriptor_table_pointer + { + /** + * @brief Default constructor. + */ + interrupt_descriptor_table_pointer() = default; + + /** + * @brief Constructor. + */ + interrupt_descriptor_table_pointer(uint16_t table_length, gate_descriptor * address); + + /** + * @brief Defaulted three-way comparsion operator. + */ + auto operator<=>(interrupt_descriptor_table_pointer const & other) const -> std::strong_ordering = default; + + private: + uint16_t table_length = {}; ///< The amount of segment descriptor entries in the global descriptor table - 1. + gate_descriptor * address = {}; ///< Non-owning pointer to the IDT base address. + }; + +} // namespace teachos::arch::context_switching::interrupt_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/ist_offset.hpp b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/ist_offset.hpp new file mode 100644 index 0000000..e45bcf4 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/ist_offset.hpp @@ -0,0 +1,45 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IST_OFFSET_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IST_OFFSET_HPP + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + /** + * @brief Defines helper function for all states that the interrupt stack table offset field of a gate descriptor can + * have. Is automatically increased to one byte in size, to include the following 5 reserved bits in the gate + * descriptor. + */ + struct [[gnu::packed]] ist_offset + { + /** + * @brief Default Constructor. + */ + ist_offset() = default; + + /** + * @brief Constructor. + * + * @param offset Offset into the interrupt stack table. A value of of 0 means we do not switch stacks, whereas 1 - 7 + * mean we switch to the n-th stack in the Interrupt Stack Table, contained in the TSS if the gate descriptor that + * contains this field is called. + */ + ist_offset(uint8_t offset); + + /** + * @brief Allows to compare the underlying set bits of two instances. + * + * @param other Other instance that we want to compare with. + * @return Whether the underlying set bits of both types are the same. + */ + auto operator==(ist_offset const & other) const -> bool = default; + + private: + uint8_t _ist : 3 = {}; ///< Offset into the interrupt stack table. A value of of 0 means we do not switch stacks, + ///< whereas 1 - 7 mean we switch to the n-th stack in the Interrupt Stack Table, contained + ///< in the TSS if the gate descriptor that contains this field is called. + }; +} // namespace teachos::arch::context_switching::interrupt_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IST_OFFSET_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp new file mode 100644 index 0000000..ea8c145 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp @@ -0,0 +1,105 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_SEGMENT_SELECTOR_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_SEGMENT_SELECTOR_HPP + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + /** + * @brief Represents a segment selector in the x86_64 architecture, which points to a valid code segment in the global + * descriptor table. + * + * A segment selector is a 16-bit identifier used to select a segment descriptor + * from the Global Descriptor Table (GDT) or the Local Descriptor Table (LDT). + * It contains an index, a table indicator (TI), and a requested privilege level (RPL). + */ + struct [[gnu::packed]] segment_selector + { + /** + * @brief Possible set bits in our underlying bits and the meaning when they are set. + */ + enum bitset : uint8_t + { + REQUEST_LEVEL_KERNEL = + 0U << 0U, ///< Highest privileged level used by the kernel to allow for full access of resources. + REQUEST_LEVEL_ADMIN = + 1U << 0U, ///< Restricts access to own application and thoose of lower privilege. Should only be used if more + ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended. + REQUEST_LEVEL_PRIVILEGED_USER = + 2U << 0U, ///< Restricts access to own application and thoose of lower privilege. Should only be used if more + ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended. + REQUEST_LEVEL_USER = 3U << 0U, ///< Restricts access to only application and their specific memory. + LOCAL_DESCRIPTOR_TABLE = 1U << 2U, ///< Wheter the index referes to an entry in the local or global descriptor + ///< table. If enabled the index points to a local descriptor table, if it is + ///< cleared it referes to a global descriptor table instead. + }; + + /** + * @brief Default constructor. + */ + segment_selector() = default; + + /** + * @brief Constructor. + * + * @param index Index into the local or global descriptor table. Processor multiplies the index value by 8 (number + * of bytes in 32-bit segment descriptor) and adds the result to the base GDT or LDT address. + * @param flags Allows to set flags for the flags field using the unscoped enum contained in this class, used to + * allow for direct integer conversion. + */ + constexpr segment_selector(uint16_t index, uint8_t flags) + : _flags(flags) + , _index(index) + { + // Nothing to do. + } + + /** + * @brief Checks if the given std::bitset is a subset or equivalent to the underlying data. + * + * @note Meaning that all bits that are set in the given std::bitset also have to be set in the underlyng + * data. Any additional bits that are set are not relevant. + * + * @param other Flags that we want to compare against and check if the underlying data has the same bits set. + * @return Whether the given flags are a subset or equivalent with the underlying data. + */ + auto contains_flags(std::bitset<3U> other) const -> bool; + + /** + * @brief Gets the index into the global descriptor table or the local descriptor table this segment selector is + * pointing too. + * + * @return Underlying value of the index field, bit 3 - 16. + */ + [[gnu::section(".user_text")]] + auto get_index() const -> uint16_t; + + /** + * @brief Defaulted three-way comparsion operator. + */ + auto operator<=>(segment_selector const & other) const -> std::strong_ordering = default; + + /** + * @brief Combines all bits that are set in the std::bitset flags with the bits already set in the underlying data. + * + * @param other Additional bits that should be set. + */ + auto operator|=(std::bitset<3U> other) -> void; + + /** + * @brief Cast the underlying data into a combined 16-bit form, that contains all data. + * + * @return Underlying value combined into it's full size. + */ + operator uint16_t() const; + + private: + uint8_t _flags : 3 = {}; ///< Underlying bits used to read the flags from. + uint16_t _index + : 13 = {}; ///< Index into the local or global descriptor table. Processor multiplies the index value by 16 + ///< (number of bytes in segment descriptor) and adds the result to the base address. + }; +} // namespace teachos::arch::context_switching::interrupt_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_SEGMENT_SELECTOR_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/main.hpp b/arch/x86_64/pre/include/arch/context_switching/main.hpp new file mode 100644 index 0000000..f8477ea --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/main.hpp @@ -0,0 +1,51 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_MAIN_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_MAIN_HPP + +#include "arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp" +#include "arch/context_switching/segment_descriptor_table/global_descriptor_table.hpp" + +namespace teachos::arch::context_switching +{ + /** + * @brief Contains the references to the tables required for context switching + */ + struct descriptor_tables + { + segment_descriptor_table::global_descriptor_table & gdt; ///< Reference to the global descriptor table. + interrupt_descriptor_table::interrupt_descriptor_table & idt; ///< Reference to the interrupt descriptor table. + }; + + /** + * @brief Creates the Interrupt Descriptor Table and Global Descriptor Table as a static variable the first time this + * method is called and update IDTR and GDTR registers values. + * + * @note Subsequent calls after the first one, will simply return the previously created tables, but not update the + * registers again. + * + * @return References to the statically created Interrupt Descriptor and Global Descriptor Table. + */ + auto initialize_descriptor_tables() -> descriptor_tables; + + /** + * @brief Switches from the current Kernel Mode (Level 0) to User Mode (Level 3). Will simply use predefined Segment + * Selectors for the User Data and User Code Segment, which are Index 3 and 4 in the GDT respectively. + */ + auto switch_to_user_mode() -> void; + + /** + * @brief Switches from the current Code and Data Segment to the given Code and Data Segment. + * + * @note This method will additionally call initialize_descriptor_tables, to ensure the GDTR and IDTR have been setup + * correctly before attempting to switch the context. This switch is achieved using a far return, which will once + * executed call the given void function. + * + * @param data_segment Data Segment that the SS, DS; ES, FS and GS register will be set too. + * @param code_segment Code Segment that the CS register will be set too. + * @param return_function Function that will be called once the switch has been achieved. + */ + auto switch_context(interrupt_descriptor_table::segment_selector data_segment, + interrupt_descriptor_table::segment_selector code_segment, void (*return_function)()) -> void; + +} // namespace teachos::arch::context_switching + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_MAIN_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/access_byte.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/access_byte.hpp new file mode 100644 index 0000000..7450330 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/access_byte.hpp @@ -0,0 +1,104 @@ + +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_ACCESS_BYTE_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_ACCESS_BYTE_HPP + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + /** + * @brief Defines helper function for all states that the access byte field of a segment descriptor can + * have. + */ + struct [[gnu::packed]] access_byte + { + /** + * @brief Possible set bits in our underlying bits and the meaning when they are set. + */ + enum bitset : uint8_t + { + ACCESSED = + 1U + << 0U, ///< Whether the segment has been accessed since the last time the operating system has cleared the + ///< flag. If enabled it has been accessed, otherwise it has not been accessed since the last clear. + WRITABLE = 1U << 1U, ///< Indicates if the data segment is writable or not. If enabled the code segment allows + ///< read and write access, otherwise only read access is possible. + READABLE = 1U << 1U, ///< Indicates if the code segment is readable or not. If enabled the code segment allows + ///< read and execute access, otherwise only executable access is possible. + CONFORMING = + 1U << 2U, ///< Indicates if the code is allowed to be executed by different access levels + ///< (higher or lower) in code segments. If enabled the code segment allows access, otherwise + ///< access from different privilege levels with throw a General-Protectione exception. + EXPAND_DOWN = 1U << 2U, ///< Indicates if the expansion direction is up or down in data segments. If enabled the + ///< data segment expands downwards, otherwise it expands upwards. + CODE_SEGMENT = 1U << 3U, ///< Further defines the actual type of the segment. If enabled this segment is a code + ///< segment, otherwise its a data segment. + LOCAL_DESCRIPTOR_TABLE = 2, ///< The actual type of sytem segment is a local descriptor table. + TASK_STATE_SEGMENT_AVAILABLE = + 9, ///< The actual type of sytem segment is a task state segment that is still available. + TASK_STATE_SEGMENT_BUSY = 11, ///< The actual type of sytem segment is a task state segment that is currently in + ///< use and therefore busy. + CALL_GATE = 11, ///< The actual type of sytem segment is a call gate. + INTERRUPT_GATE = 14, ///< The actual type of sytem segment is a interrupt gate. + TRAP_GATE = 15, ///< The actual type of sytem segment is a trap gate. + CODE_OR_DATA_SEGMENT = 1U << 4U, ///< Defines a system segment (if 0) or a code/data segment (if 1). + DESCRIPTOR_LEVEL_KERNEL = + 0U << 5U, ///< Highest privileged level used by the kernel to allow for full access of resources. + DESCRIPTOR_LEVEL_ADMIN = + 1U << 5U, ///< Restricts access to own application and thoose of lower privilege. Should only be used if more + ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended. + DESCRIPTOR_LEVEL_PRIVILEGED_USER = + 2U << 5U, ///< Restricts access to own application and thoose of lower privilege. Should only be used if more + ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended. + DESCRIPTOR_LEVEL_USER = 3U << 5U, ///< Restricts access to only application and their specific memory. + PRESENT = 1U << 7U, ///< Present bit; Allows an entry to refer to a valid segment. + ///< Must be set (1) for any valid segment. + }; + + /** + * @brief Default Constructor. + */ + access_byte() = default; + + /** + * @brief Constructor. + * + * @param flags Allows to set flags for the access byte field using the unscoped enum contained in this class, used + * to allow for direct integer conversion. This value is saved and can later be used to check whether certain flags + * are enabled or not using contains_flags method. + */ + access_byte(uint8_t flags); + + /** + * @brief Checks if the given std::bitset is a subset or equivalent to the underlying data. + * + * @note Meaning that all bits that are set in the given std::bitset also have to be set in the underlyng + * data. Any additional bits that are set are not relevant. + * + * @param other Flags that we want to compare against and check if the underlying data has the same bits set. + * @return Whether the given flags are a subset or equivalent with the underlying data. + */ + auto contains_flags(std::bitset<8U> other) const -> bool; + + /** + * @brief Allows to compare the underlying data of two instances. + * + * @param other Other instance that we want to compare with. + * @return Whether the underlying data of both types is the same. + */ + auto operator==(access_byte const & other) const -> bool = default; + + /** + * @brief Combines all bits that are set in the std::bitset flags with the bits already set in the underlying data. + * + * @param other Additional bits that should be set. + */ + auto operator|=(std::bitset<8U> other) -> void; + + private: + uint8_t _flags = {}; ///< Underlying bits used to read the flags from. + }; +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_ACCESS_BYTE_HPP
\ No newline at end of file diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/gdt_flags.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/gdt_flags.hpp new file mode 100644 index 0000000..e24b988 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/gdt_flags.hpp @@ -0,0 +1,93 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GDT_FLAGS_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GDT_FLAGS_HPP + +#include "arch/context_switching/segment_descriptor_table/segment_descriptor_type.hpp" + +#include <bitset> + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + /** + * @brief Defines helper function for all states that the flags field of a segment descriptor can + * have. + */ + struct [[gnu::packed]] gdt_flags + { + /** + * @brief Possible set bits in our underlying bits and the meaning when they are set. + */ + enum bitset : uint8_t + { + LONG_MODE = 1U << 1U, ///< Defines in IA-32e mode (64-bit code and 32-bit compatability mode) if the segment + ///< contains 64-bit code. Otherwise this bit should always be 0. Enable if instructions + ///< are executed in 64-bit code, otherwise they are executed in compatability 32-bit mode. + ///< If this bit is set the 3rd bit needs to be clear (0). + UPPER_BOUND = 1U << 2U, ///< Specifies the upper bound of the segment for expand down data segment. Enable for 4 + ///< GiB, 4 KiB otherwise. + STACK_POINTER_SIZE = 1U << 2U, ///< Specifies the size of the Stack Pointer (SP) for stack segments used for + ///< implicit stack operations. Enable for 32 bit, 16 bit otherwise. + DEFAULT_LENGTH = 1U << 2U, ///< Indicates the default length for code segments with effective addresses and + ///< operands. Enable for 32 bit, 16 bit otherwise. + GRANULARITY = 1U << 3U, ///< Indicates the size the Limit value in the segment descriptor is scaled by 1 Byte + ///< blocks if the bit is not set or by 4 KiB blocks if the bit is set. + }; + + /** + * @brief Default Constructor. + */ + gdt_flags() = default; + + /** + * @brief Constructor. + * + * @param flags Allows to set flags for the flags field using the unscoped enum contained in this class, used to + * allow for direct integer conversion. This value is saved and can later be used to check whether certain flags are + * enabled or not using contains_flags method. + * @param limit Does not necessarily make sense in the gdt flags type, but because the flags alone are only 4 bit + * the type would still require the space for a complete bit. Therefore the 4 bit segment limit field before the + * flags field is included in this type to ensure we actually contain 8 bit of data. + */ + gdt_flags(uint8_t flags, std::bitset<20U> limit); + + /** + * @brief Checks if the given std::bitset is a subset or equivalent to the underlying data. + * + * @note Meaning that all bits that are set in the given std::bitset also have to be set in the underlyng + * data. Any additional bits that are set are not relevant. + * + * @param other Flags that we want to compare against and check if the underlying data has the same bits set. + * @return Whether the given flags are a subset or equivalent with the underlying data. + */ + auto contains_flags(std::bitset<4U> other) const -> bool; + + /** + * @brief Get part of the segment limit that is saved in the gdt flags. This does not necessarily make sense in this + * object, but it has to be included here because a struct can not be smaller than a full byte. Therefore we include + * the 4 bit segment limit field so that it results in a compelte byte with the addtional 4 bit of gdt flags. + * + * @return 4-bit limit segment + */ + auto get_limit() const -> std::bitset<4U>; + + /** + * @brief Allows to compare the underlying set bits of two instances. + * + * @param other Other instance that we want to compare with. + * @return Whether the underlying set bits of both types are the same. + */ + auto operator==(gdt_flags const & other) const -> bool = default; + + /** + * @brief Combines all bits that are set in the std::bitset flags with the bits already set in the underlying data. + * + * @param other Additional bits that should be set. + */ + auto operator|=(std::bitset<4U> other) -> void; + + private: + uint8_t _limit_2 : 4 = {}; ///< Second part of the limit field. + uint8_t _flags : 4 = {}; ///< Underlying bits used to read the flags from. + }; +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GDT_FLAGS_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/global_descriptor_table.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/global_descriptor_table.hpp new file mode 100644 index 0000000..44f2692 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/global_descriptor_table.hpp @@ -0,0 +1,37 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GLOBAL_DESCRIPTOR_TABLE_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GLOBAL_DESCRIPTOR_TABLE_HPP + +#include "arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp" +#include "arch/context_switching/segment_descriptor_table/task_state_segment.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + /** + * @brief Creates the global descriptor table, with the minimum required configuration. If this method is called more + * than once, the previously created instance is returned instead. + * + * @return Reference to the created global_descriptor_table. + */ + auto get_or_create_gdt() -> global_descriptor_table &; + + /** + * @brief Updates the GDTR with the created global descriptor table. If it has not been created yet this + * method will create it. + * + * @note This method will only set the GDTR, but for the processor to actually register the change a far jump + * has to be executed. This also has to be done before updating the TR. + */ + auto update_gdtr() -> void; + + /** + * @brief Updates the TR with the created task state segment. If it has not been created yet this + * method will create it. + * + * @note This method should only be called after update_gdtr() and a far jump has been + * executed. Because before that trying to access the segment will cause an exception. + */ + auto update_tss_register() -> void; + +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GLOBAL_DESCRIPTOR_TABLE_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp new file mode 100644 index 0000000..292ff70 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp @@ -0,0 +1,41 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GLOBAL_DESCRIPTOR_TABLE_POINTER_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GLOBAL_DESCRIPTOR_TABLE_POINTER_HPP + +#include "arch/stl/vector.hpp" + +#include <cstdint> + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + using global_descriptor_table = stl::vector<uint64_t>; + + /** + * @brief Represents a pointer to the Global Descriptor Table (GDT). + * + * This structure is used to store the base address and length of the GDT. + * It is used when loading or modifying the GDT during context switching. + */ + struct [[gnu::packed]] global_descriptor_table_pointer + { + /** + * @brief Default constructor. + */ + global_descriptor_table_pointer() = default; + + /** + * @brief Constructor. + */ + global_descriptor_table_pointer(uint16_t table_length, uint64_t * address); + + /** + * @brief Defaulted three-way comparsion operator. + */ + auto operator<=>(global_descriptor_table_pointer const & other) const -> std::strong_ordering = default; + + private: + uint16_t table_length = {}; ///< The amount of segment descriptor entries in the global descriptor table - 1. + uint64_t * address = {}; ///< Non-owning pointer to the GDT base address. + }; +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_GLOBAL_DESCRIPTOR_TABLE_POINTER_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_base.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_base.hpp new file mode 100644 index 0000000..933fb4d --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_base.hpp @@ -0,0 +1,73 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_BASE_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_BASE_HPP + +#include "arch/context_switching/segment_descriptor_table/access_byte.hpp" +#include "arch/context_switching/segment_descriptor_table/gdt_flags.hpp" +#include "arch/context_switching/segment_descriptor_table/segment_descriptor_type.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + /** + * @brief Defines helper function for all states and the actual data the segment descriptor can have. + */ + struct [[gnu::packed]] segment_descriptor_base + { + /** + * @brief Default Constructor. + */ + segment_descriptor_base() = default; + + /** + * @brief Constructor. + * + * @note Created segment descriptor copies the given bytes into these components requiring the space of one + * segment descriptor entry in the global descriptor table being 64-bit. + * - 8 bit Access Type + * - 4 bit Flags + * - 32 bit Base Address + * - 20 bit Limit + * + * @param flags Copies the bits set from the given data into the individual components of a segment + * descriptor. + */ + explicit segment_descriptor_base(uint64_t flags); + + /** + * @brief Constructor. + * + * @param access_byte, flags, base, limit Copies the bits set from the given data into the individual components of + * a segment descriptor. + */ + segment_descriptor_base(access_byte access_byte, gdt_flags flags, uint32_t base, std::bitset<20U> limit); + + /** + * @brief Calculates the underlying segment type that this segement descriptor is describing. + */ + auto get_segment_type() const -> segment_descriptor_type; + + /** + * @brief Cast the underlying data into a combined 64-bit form, that contains all data. + * + * @return Underlying value combined into it's full size. + */ + operator uint64_t() const; + + /** + * @brief Allows to compare the underlying bits of two instances. + * + * @param other Other instance that we want to compare with. + * @return Whether the underlying set bits of both types are the same. + */ + auto operator==(segment_descriptor_base const & other) const -> bool = default; + + private: + // The order in private variables starts for the first variable being the rightmost bit. + uint16_t _limit_1 = {}; ///< First part of the limit field (0 - 15) + uint32_t _base_1 : 24 = {}; ///< First part of the base field (16 - 39) + access_byte _access = {}; ///< Access byte field (40 - 47) + gdt_flags _flag = {}; ///< Second part of the limit field + Flags field (48 - 55) + uint8_t _base_2 = {}; ///< Second part of the base field (56 - 63) + }; +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_BASE_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_extension.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_extension.hpp new file mode 100644 index 0000000..40bcc8a --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_extension.hpp @@ -0,0 +1,74 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_EXTENSION_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_EXTENSION_HPP + +#include "arch/context_switching/segment_descriptor_table/segment_descriptor_base.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + __extension__ typedef __int128 int128_t; + __extension__ typedef unsigned __int128 uint128_t; + + /** + * @brief Defines helper function for all states and the actual data the segment descriptor can have. + */ + struct [[gnu::packed]] segment_descriptor_extension + { + /** + * @brief Default Constructor. + */ + segment_descriptor_extension() = default; + + /** + * @brief Constructor. + * + * @note Created segment descriptor copies the given bytes into these components requiring the space of two + * segment descriptor entry in the global descriptor table being 128-bit. Ending with a 32 bit reserved + * field that has to be used, because the segment descriptor needs to be big enough for two segment + * descriptor entries. + * - 8 bit Access Type + * - 4 bit Flags + * - 64 bit Base Address + * - 20 bit Limit + * + * @param flags Copies the bits set from the given data into the individual components of a segment + * descriptor. + */ + explicit segment_descriptor_extension(uint128_t flags); + + /** + * @brief Constructor. + * + * @param access_byte, flags, base, limit Copies the bits set from the given data into the individual components of + * a segment descriptor. + */ + segment_descriptor_extension(access_byte access_byte, gdt_flags flags, uint64_t base, std::bitset<20U> limit); + + /** + * @brief Returns the underlying base segment descriptor, being the first part of the segment descriptor consisting + * of two entries in the global descriptor table. + */ + auto get_first_gdt_entry() const -> segment_descriptor_base; + + /** + * @brief Returns the underlying extension to the segment descriptor, being the second part of the segment + * descriptor consiting of two entries in the global descriptor table. + */ + auto get_second_gdt_entry() const -> uint64_t; + + /** + * @brief Allows to compare the underlying bits of two instances. + * + * @param other Other instance that we want to compare with. + * @return Whether the underlying set bits of both types are the same. + */ + auto operator==(segment_descriptor_extension const & other) const -> bool = default; + + private: + // The order in private variables starts for the first variable being the rightmost bit. + segment_descriptor_base _base = {}; ///< Base Segment Descriptor representing single entry in GDT (0 - 63) + uint32_t _base_3 = {}; ///< Third part of the base field (63 - 95) + uint32_t : 32; ///< Reserved field used to ensure this struct is 128 bits big (96 - 127) + }; +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_EXTENSION_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_type.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_type.hpp new file mode 100644 index 0000000..8770b81 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/segment_descriptor_type.hpp @@ -0,0 +1,27 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_TYPES_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_TYPES_HPP + +#include <cstdint> + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + /** + * @brief Possible overlying types of the segment descriptor. Allowing to discern between the major types, which + * result in different handling of the actual data contained in the descriptor. + */ + enum class segment_descriptor_type : uint8_t + { + SYSTEM_SEGMENT, ///< The segment is of type system, is distinguished by the Descriptor Type field in the Access + ///< Byte. Can be further distinguised to specific system segment types using the Type Field in the + ///< Access Byte. + DATA_SEGMENT, ///< The segment is of type data, is is distinguished by the Descriptor Type field in the Access + ///< Byte and the first bit of the Type Field in the Access Byte. Can be further distinguised to + ///< specific data segment types using the the remaining bits in the Type Field in the Access Byte. + CODE_SEGMENT, ///< The segment is of type code, is is distinguished by the Descriptor Type field in + ///< the Access Byte and the first bit of the Type Field in the Access Byte. Can be + ///< further distinguised to specific data segment types using the the remaining bits in + ///< the Type Field in the Access Byte. + }; +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_SEGMENT_DESCRIPTOR_TYPES_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/task_state_segment.hpp b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/task_state_segment.hpp new file mode 100644 index 0000000..d4aa5e8 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/segment_descriptor_table/task_state_segment.hpp @@ -0,0 +1,32 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_TASK_STATE_SEGMENT_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_TASK_STATE_SEGMENT_HPP + +#include <cstdint> + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + /** + * @brief 64-bit task state segment + */ + struct [[gnu::packed]] task_state_segment + { + private: + uint32_t : 32; + uint64_t rsp0 = {}; + uint64_t rsp1 = {}; + uint64_t rsp2 = {}; + uint64_t : 64; + uint64_t ist1 = {}; + uint64_t ist2 = {}; + uint64_t ist3 = {}; + uint64_t ist4 = {}; + uint64_t ist5 = {}; + uint64_t ist6 = {}; + uint64_t ist7 = {}; + uint64_t : 64; + uint16_t : 16; + uint16_t io_map_base_address = {}; + }; +} // namespace teachos::arch::context_switching::segment_descriptor_table + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SEGMENT_DESCRIPTOR_TABLE_TASK_STATE_SEGMENT_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/syscall/main.hpp b/arch/x86_64/pre/include/arch/context_switching/syscall/main.hpp new file mode 100644 index 0000000..f507c61 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/syscall/main.hpp @@ -0,0 +1,91 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_MAIN_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_MAIN_HPP + +#include <cstdint> + +namespace teachos::arch::context_switching::syscall +{ + /** + * @brief Possible syscall implementation that should actually be called. + * + * @note Attempts to reflect the Linux interface partially. See https://filippo.io/linux-syscall-table/ for more + * information. + */ + enum class type : uint64_t + { + WRITE = 1U, ///< Loads the arg_0 parameter as an address pointing to a const char array, which will then be printed + ///< onto the VGA buffer screen. + EXPAND_HEAP = 2U, /// Expands the User Heap by additonally mapping 100 KiB of virtual page memory. Ignores the + /// parameters and uses them as out parameters instead, where arg_0 is the start of the newly + /// mapped heap area and arg_1 is the size of the entire area. Can be less than 100 KiB if less + /// space remains. + ASSERT = 3U, /// Loads the arg_0 parameter as a boolean which needs to be true or it will print the message in + /// arg_1 parameter onto the VGA buffer screen, keep it as a nullptr if it shouldn't print anything + /// and then it halts the further execution of the application. + }; + + /** + * @brief Possible error codes that can be returned by the different syscall methods called depending on the type + * enum. + */ + enum class error : uint8_t + { + OK = 0U, ///< No error occured in syscall. + OUT_OF_MEMORY = 1U, ///< Expanding heap failed because we have run out of mappable virtual address space. + }; + + /** + * @brief Allows to convert the error enum type into a boolean directly. Where any code besides 0 being no error, will + * return true. The remaining errors return true. + * + * @param e Error code that was returned by the syscall. + * @return Return true if there was no error and false otherwise. + */ + constexpr bool operator!(error e) + { + return e == error::OK; + } + + /** + * @brief Maximum amount of arguments that can be passed to a syscall. Default value is 0 and arguments are only ever + * used depending on the actual enum type and if the method requires thoose parameters. + */ + struct arguments + { + uint64_t arg_0{}; ///< First optional paramter to the syscall representing the RDI register. + uint64_t arg_1{}; ///< Second optional paramter to the syscall representing the RSI register. + uint64_t arg_2{}; ///< Third optional paramter to the syscall representing the RDX register. + uint64_t arg_3{}; ///< Fourth optional paramter to the syscall representing the R10 register. + uint64_t arg_4{}; ///< Fifth optional paramter to the syscall representing the R8 register. + uint64_t arg_5{}; ///< Sixth optional paramter to the syscall representing the R9 register. + }; + + /** + * @brief Response of a systemcall always containin an error code, signaling if the syscall even succeeded or not. + * Additionally it may contain up to 6 return values in the values struct. + */ + struct response + { + error error_code; ///< Error code returned by the syscall. If it failed all the values will be 0. + arguments values = {}; ///< Optional return values of the syscall implementation. + }; + + /** + * @brief Calls the method associated with the given syscall number and passes the given optional arguments to it, + * over the RDI, RSI, RDX, R10, R8 and R9 register. + * + * @param syscall_number Syscall method that should be called. See enum values in type for possible implemented + * methods. + * @param args Optional arguments passable to the different syscall methods, called depending on the syscall_number. + * Not passing the required parameters to the method, will result in passing 0 instead, which might make the fail or + * not function correctly. + * @return The syscall implementation always returns a bool-convertable error code converting to true if the syscall + * failed or false if it didn't. Additionally it might pase additional values besides the error code, they will be set + * in the arguments struct. So the value can be read and used for further processing. + */ + [[gnu::section(".user_text")]] + auto syscall(type syscall_number, arguments args = {}) -> response; + +} // namespace teachos::arch::context_switching::syscall + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_MAIN_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/syscall/syscall_enable.hpp b/arch/x86_64/pre/include/arch/context_switching/syscall/syscall_enable.hpp new file mode 100644 index 0000000..8cb468a --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/syscall/syscall_enable.hpp @@ -0,0 +1,18 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_SYSCALL_ENABLE_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_SYSCALL_ENABLE_HPP + +namespace teachos::arch::context_switching::syscall +{ + /** + * @brief Enables and sets up internal CPU registers to allow for syscall to function correctly and switch context + * temporarily back to the kernel level. + * + * @note Configures the Model Specific Register required by syscall (LSTAR, FMASK, STAR) with the correct values so + * that the syscall_handler is called and sets the System Call Extension bit on the EFER flags to allow for syscall + * to be used. + */ + auto enable_syscall() -> void; + +} // namespace teachos::arch::context_switching::syscall + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_SYSCALL_ENABLE_HPP diff --git a/arch/x86_64/pre/include/arch/context_switching/syscall/syscall_handler.hpp b/arch/x86_64/pre/include/arch/context_switching/syscall/syscall_handler.hpp new file mode 100644 index 0000000..2e7bcd1 --- /dev/null +++ b/arch/x86_64/pre/include/arch/context_switching/syscall/syscall_handler.hpp @@ -0,0 +1,18 @@ +#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_SYSCALL_HANDLER_HPP +#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_SYSCALL_HANDLER_HPP + +#include <cstdint> + +namespace teachos::arch::context_switching::syscall +{ + /** + * @brief Handler for SYSCALL instruction. Calls a specific implementation based + * on the register RAX. + * + * @return Returns with LEAVE, SYSRETQ + */ + auto syscall_handler() -> void; + +} // namespace teachos::arch::context_switching::syscall + +#endif // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_SYSCALL_SYSCALL_HANDLER_HPP diff --git a/arch/x86_64/pre/include/arch/exception_handling/assert.hpp b/arch/x86_64/pre/include/arch/exception_handling/assert.hpp new file mode 100644 index 0000000..1286768 --- /dev/null +++ b/arch/x86_64/pre/include/arch/exception_handling/assert.hpp @@ -0,0 +1,17 @@ +#ifndef TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_ASSERT_HPP +#define TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_ASSERT_HPP + +namespace teachos::arch::exception_handling +{ + /** + * @brief Assert a condition to be true, if not do not continue + * execution of the code and print the given message to screen. + * + * @param condition Condition we want to be true or else halt execution. + * @param message Message that should be printed before halting the execution if the condition is not met. + */ + auto assert(bool condition, char const * message) -> void; + +} // namespace teachos::arch::exception_handling + +#endif // TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_ASSERT_HPP diff --git a/arch/x86_64/pre/include/arch/exception_handling/panic.hpp b/arch/x86_64/pre/include/arch/exception_handling/panic.hpp new file mode 100644 index 0000000..6a2404c --- /dev/null +++ b/arch/x86_64/pre/include/arch/exception_handling/panic.hpp @@ -0,0 +1,23 @@ +#ifndef TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_PANIC_HPP +#define TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_PANIC_HPP + +namespace teachos::arch::exception_handling +{ + /** + * @brief Print the given kernel panic message and then halt the system. + * + * @param reason Reason to print before halting the system. + */ + [[noreturn]] auto panic(char const * reason) -> void; + + /** + * @brief Print the given kernel panic message started by a given prefix and then halt the system. + * + * @param prefix Prefix to print before printing the reason. + * @param reason Reason to print before halting the system. + */ + [[noreturn]] auto panic(char const * prefix, char const * reason) -> void; + +} // namespace teachos::arch::exception_handling + +#endif // TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_PANIC_HPP diff --git a/arch/x86_64/pre/include/arch/interrupt_handling/generic_interrupt_handler.hpp b/arch/x86_64/pre/include/arch/interrupt_handling/generic_interrupt_handler.hpp new file mode 100644 index 0000000..15b35c1 --- /dev/null +++ b/arch/x86_64/pre/include/arch/interrupt_handling/generic_interrupt_handler.hpp @@ -0,0 +1,34 @@ +#ifndef TEACHOS_ARCH_X86_64_INTERRUPT_HANDLING_GENERIC_INTERRUPT_HANDLER_HPP +#define TEACHOS_ARCH_X86_64_INTERRUPT_HANDLING_GENERIC_INTERRUPT_HANDLER_HPP + +#include <cstdint> + +namespace teachos::arch::interrupt_handling +{ + /** + * @brief Represents the CPU state during an interrupt. + * + * Some interrupts push an error code, while others do not. The full list + * of which vector number contains the error code can be found here: https://wiki.osdev.org/Exceptions + */ + struct [[gnu::packed]] interrupt_frame + { + // uint64_t error_code; ///< Error code only pushed by some exceptions, therefore it is commented out. + uint64_t ip; ///< Instruction pointer at the time of the interrupt. + uint64_t cs; ///< Code segment selector indicating privilege level. + uint64_t flags; ///< CPU flags (RFLAGS) storing processor state. + uint64_t sp; ///< Stack pointer at the time of the interrupt. + uint64_t ss; ///< Stack segment selector, usually unused in 64-bit mode. + }; + + /** + * @brief Generic interrupt handler function. + * + * @param frame Pointer to the interrupt frame containing CPU state. + */ + [[gnu::interrupt]] + auto generic_interrupt_handler(interrupt_frame * frame) -> void; + +} // namespace teachos::arch::interrupt_handling + +#endif // TEACHOS_ARCH_X86_64_INTERRUPT_HANDLING_GENERIC_INTERRUPT_HANDLER_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/cpu/call.hpp b/arch/x86_64/pre/include/arch/kernel/cpu/call.hpp new file mode 100644 index 0000000..3c43304 --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/cpu/call.hpp @@ -0,0 +1,30 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP + +#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp" + +#include <cstdint> + +namespace teachos::arch::kernel::cpu +{ + /** + * @brief Far Pointer. Address to function located in another code segment. + */ + struct far_pointer + { + void (*function)(); ///< Address of the function we want to call. (0-63) + context_switching::interrupt_descriptor_table::segment_selector + selector; ///< Segment selector pointing to the GDT entry we want to load into register CS. (64-79) + }; + + /** + * @brief Far call - A call to an instruction located in a different segment than the current code segment but at the + * same privilege level. + * + * @param pointer 64-bit operand size far pointer that we want to call. + */ + auto call(far_pointer pointer) -> void; + +} // namespace teachos::arch::kernel::cpu + +#endif // TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/cpu/gdtr.hpp b/arch/x86_64/pre/include/arch/kernel/cpu/gdtr.hpp new file mode 100644 index 0000000..68b950d --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/cpu/gdtr.hpp @@ -0,0 +1,27 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_GDTR_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_CPU_GDTR_HPP + +#include "arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp" + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::kernel::cpu +{ + + /** + * @brief Returns the value in the GDTR register. + * + * @return Value of GDTR register. + */ + auto store_global_descriptor_table() -> context_switching::segment_descriptor_table::global_descriptor_table_pointer; + + /** + * @brief Loads the global_descriptor_table_pointer into the global descriptor table register (GDTR). + */ + auto load_global_descriptor_table( + context_switching::segment_descriptor_table::global_descriptor_table_pointer const & gdt_pointer) -> void; + +} // namespace teachos::arch::kernel::cpu + +#endif // TEACHOS_ARCH_X86_64_KERNEL_CPU_GDTR_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/cpu/idtr.hpp b/arch/x86_64/pre/include/arch/kernel/cpu/idtr.hpp new file mode 100644 index 0000000..cb800d0 --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/cpu/idtr.hpp @@ -0,0 +1,27 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_IDTR_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_CPU_IDTR_HPP + +#include "arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp" + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::kernel::cpu +{ + /** + * @brief Returns the value in the IDTR register. + * + * @return Value of IDTR register. + */ + auto store_interrupt_descriptor_table() + -> context_switching::interrupt_descriptor_table::interrupt_descriptor_table_pointer; + + /** + * @brief Loads the interrupt_descriptor_table_pointer into the interrupt descriptor table register (IDTR). + */ + auto load_interrupt_descriptor_table( + context_switching::interrupt_descriptor_table::interrupt_descriptor_table_pointer const & idt_pointer) -> void; + +} // namespace teachos::arch::kernel::cpu + +#endif // TEACHOS_ARCH_X86_64_KERNEL_CPU_IDTR_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/cpu/if.hpp b/arch/x86_64/pre/include/arch/kernel/cpu/if.hpp new file mode 100644 index 0000000..48707dc --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/cpu/if.hpp @@ -0,0 +1,21 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_IF_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_CPU_IF_HPP + +namespace teachos::arch::kernel::cpu +{ + /** + * @brief Sets the interrupt flag (IF) in the EFLAGS register. + * This allows the processor to respond to maskable hardware interrupts. + */ + auto set_interrupt_flag() -> void; + + /** + * @brief Clears the interrupt flag (IF) in the EFLAGS register. + * This will stop the processor to respond to maskable hardware interrupts and needs to be done before changing the + * Interrupt Descriptor Table with lidt. + */ + auto clear_interrupt_flag() -> void; + +} // namespace teachos::arch::kernel::cpu + +#endif // TEACHOS_ARCH_X86_64_KERNEL_CPU_IF_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/cpu/msr.hpp b/arch/x86_64/pre/include/arch/kernel/cpu/msr.hpp new file mode 100644 index 0000000..99d6378 --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/cpu/msr.hpp @@ -0,0 +1,64 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_NXE_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_CPU_NXE_HPP + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::kernel::cpu +{ + /** + * @brief Important flags that can be writen into the Extended Feature Enable Register (EFER). + * + * @note EFER is a model-specific register allowing to configure CPU extensions. Only the most important extensions + * are listed below, the rest are excluded for brevity. See https://en.wikipedia.org/wiki/Control_register#EFER for + * more information. + */ + enum class efer_flags : uint64_t + { + SCE = 1UL << 0UL, ///< System Call Extensions. + LME = 1UL << 8UL, ///< Long Mode Enabled. + LMA = 1UL << 10UL, ///< Long Mode Active. + NXE = 1UL << 11UL, ///< No-Execute Enable. + SVME = 1UL << 12UL, ///< Secure Virtual Machine Enable. + LMSLE = 1UL << 13UL, ///< Long Mode Segment Limit Enable. + FFXSR = 1UL << 14UL, ///< Fast FXSAVE/FXSTOR. + TCE = 1UL << 15UL, ///< Translation Cache Extension. + }; + + /** + * @brief Reads a 64-bit from the Model-Specific Register (MSR). + * + * @note This function reads the value of an MSR specified by the given address. It combines the lower and upper + * 32-bits of the MSR value read using the 'rdmsr' instruction and returns it as a 64-bit unsigned integer. + * + * @param msr The address of the MSR to read. + * @return The 64-bit value read from the MSR. + */ + auto read_msr(uint32_t msr) -> uint64_t; + + /** + * @brief Writes a 64-bit value to a Model-Specific Register (MSR). + * + * @note This function writes a 64-bit value to the MSR specified by the given address. + * It splits the 64-bit value into two 32-bit parts and writes them using the + * `wrmsr` instruction. + * + * @param msr The address of the MSR to write to. + * @param new_value The 64-bit value to write to the MSR. + */ + auto write_msr(uint32_t msr, uint64_t new_value) -> void; + + /** + * @brief Sets a specific bit in the Extended Feature Enable Register (EFER), which is a Model-Specific Register + * (MSR). + * + * @note This function reads the current value of the EFER register, ORs the specified + * bit with the current value, and writes the updated value back to the EFER register. + * + * @param flag The flag to set in the EFER register. + */ + auto set_efer_bit(efer_flags flag) -> void; + +} // namespace teachos::arch::kernel::cpu + +#endif // TEACHOS_ARCH_X86_64_KERNEL_CPU_NXE_HPP
\ No newline at end of file diff --git a/arch/x86_64/pre/include/arch/kernel/cpu/segment_register.hpp b/arch/x86_64/pre/include/arch/kernel/cpu/segment_register.hpp new file mode 100644 index 0000000..a236452 --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/cpu/segment_register.hpp @@ -0,0 +1,97 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_SEGMENT_REGISTER_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_CPU_SEGMENT_REGISTER_HPP + +#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp" + +namespace teachos::arch::kernel::cpu +{ + /** + * @brief Clear all Data Segment registers (DS / ES / FS / GS). + */ + auto reload_data_segment_registers() -> void; + + /** + * @brief Updates the value of the Data Segment Register (DS), Extra Segment Register (ES), Thread-Local Storage + * Registers (FS / GS). + * + * @note The Stack Segment Register (SS) value should also be updated, but the value can not be directly set in + * comparsion to the other registers. This is the case because the register is used for stack management and can not + * be directly changed, instead this has to be done by a special instruction. Therefore + * validate_data_segment_registers should only be called after set_code_segment_register has been called as well. + * + * @param data_segment Value that should be loaded into the registers. + */ + auto set_data_segment_registers(context_switching::interrupt_descriptor_table::segment_selector data_segment) -> void; + + /** + * @brief Returns the Segment Selector pointing to the Code Segment that has been loaded into the Code Segment + * Register (CS). + * + * @note The CS register can not be directly changed, instead a Far Return has to be executed to change it + * + * @return Segment Selector pointing to the currently loaded Code Segment. + */ + [[gnu::section(".user_text")]] + auto read_code_segment_register() -> context_switching::interrupt_descriptor_table::segment_selector; + + /** + * @brief Validates that all Data Segment Registers (DS / ES / FS / GS / SS) are the same as the given Data Segment + * and asserts and stops the application if they are not. + * + * @note This is only the case after set_code_segment_register has been executed as well, because it makes a far + * return that updates the SS register. + * + * @param data_segment Value that should be loaded into all Data Segment Registers. + */ + auto validate_data_segment_registers(context_switching::interrupt_descriptor_table::segment_selector data_segment) + -> void; + + /** + * @brief Validates that the Code Segment Register (CS) is the same as the given Code Segment + * and asserts and stops the application if they are not. + * + * @param code_segment Value that should be loaded into the Code Segment Register. + */ + auto validate_code_segment_register(context_switching::interrupt_descriptor_table::segment_selector code_segment) + -> void; + + /** + * @brief Simply forwards the call to validate_data_segment_registers and validate_code_segment_register and ensures + * that all Segment Registers, have been configured correctly. + * + * @note If all Segment Register have been set correctly the Context Switch using the set_code_segment_register method + * was successfull and the Privilege Level has been changed. + * + * @param data_segment Value that should be loaded into all Data Segment Registers. + * @param code_segment Value that should be loaded into the Code Segment Register. + */ + auto validate_segment_registers(context_switching::interrupt_descriptor_table::segment_selector data_segment, + context_switching::interrupt_descriptor_table::segment_selector code_segment) -> void; + + /** + * @brief Sets the value of the Code Segment Register (CS), this is achieved using a Far Return. + * + * @note The Far Return used by this method, will cause the context to switch, because we are changing from the + * current Code Segment and it's associated Privilege Level to another Code Segment. The given method will then be + * called in the new context and it should be possible to call validate_segment_registers, with the same values + * without assertions if the switch was successful. + * + * To achieve this Far Return we call IRETQ, which expects the stack to be defined a certain way to achieve that we: + * 1. Push the Data Segment Selector + * 2. Push the current Stack Pointer + * 3. Push Eflags + * 4. Push Code Segment Selector + * 5. Push Return Address + * + * @param data_segment Data Segment that should be loaded into the SS register. + * @param code_segment Code Segment that should be loaded into the CS register. + * @param address Function that we want to call in the new context created by the given Code Segment. + */ + [[gnu::naked]] + auto set_code_segment_register(context_switching::interrupt_descriptor_table::segment_selector data_segment, + context_switching::interrupt_descriptor_table::segment_selector code_segment, + uint64_t address) -> void; + +} // namespace teachos::arch::kernel::cpu + +#endif // TEACHOS_ARCH_X86_64_KERNEL_CPU_SEGMENT_REGISTER_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/cpu/tr.hpp b/arch/x86_64/pre/include/arch/kernel/cpu/tr.hpp new file mode 100644 index 0000000..7c856f1 --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/cpu/tr.hpp @@ -0,0 +1,24 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_TR_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_CPU_TR_HPP + +#include <bitset> +#include <cstdint> + +namespace teachos::arch::kernel::cpu +{ + + /** + * @brief Returns the value in the LTR register. + * + * @return Value of LTR register. + */ + auto store_task_register() -> uint16_t; + + /** + * @brief Loads the gdt offset to the tss segment descriptor into the task register (TR). + */ + auto load_task_register(uint16_t gdt_offset) -> void; + +} // namespace teachos::arch::kernel::cpu + +#endif // TEACHOS_ARCH_X86_64_KERNEL_CPU_TR_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/halt.hpp b/arch/x86_64/pre/include/arch/kernel/halt.hpp new file mode 100644 index 0000000..377acc0 --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/halt.hpp @@ -0,0 +1,13 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_HALT_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_HALT_HPP + +namespace teachos::arch::kernel +{ + /** + * @brief Halts the kernel execution, meaning any code after a call to this will not run anymore. + */ + extern "C" [[noreturn]] auto halt() -> void; + +} // namespace teachos::arch::kernel + +#endif // TEACHOS_ARCH_X86_64_KERNEL_HALT_HPP diff --git a/arch/x86_64/pre/include/arch/kernel/main.hpp b/arch/x86_64/pre/include/arch/kernel/main.hpp new file mode 100644 index 0000000..a13e5f4 --- /dev/null +++ b/arch/x86_64/pre/include/arch/kernel/main.hpp @@ -0,0 +1,13 @@ +#ifndef TEACHOS_ARCH_X86_64_KERNEL_MAIN_HPP +#define TEACHOS_ARCH_X86_64_KERNEL_MAIN_HPP + +namespace teachos::arch::kernel +{ + /** + * @brief Initalizes the kernel system. + */ + auto main() -> void; + +} // namespace teachos::arch::kernel + +#endif // TEACHOS_ARCH_X86_64_KERNEL_MAIN_HPP diff --git a/arch/x86_64/pre/include/arch/memory/heap/bump_allocator.hpp b/arch/x86_64/pre/include/arch/memory/heap/bump_allocator.hpp new file mode 100644 index 0000000..011f45c --- /dev/null +++ b/arch/x86_64/pre/include/arch/memory/heap/bump_allocator.hpp @@ -0,0 +1,48 @@ +#ifndef TEACHOS_ARCH_X86_64_MEMORY_HEAP_BUMP_ALLOCATOR_HPP +#define TEACHOS_ARCH_X86_64_MEMORY_HEAP_BUMP_ALLOCATOR_HPP + +#include "arch/memory/heap/heap_allocator.hpp" + +#include <atomic> +#include <cstdint> + +namespace teachos::arch::memory::heap +{ + /** + * @brief Simple heap allocator, which allocates linearly and leaks all allocated memory, because it does not really + * deallocate anything. + */ + struct bump_allocator : heap_allocator + { + /** + * @brief Constructor. + * + * @param heap_start Start of the allocatable heap area + * @param heap_end End of the allocatable heap area (Start + Size) + */ + bump_allocator(std::size_t heap_start, std::size_t heap_end) + : heap_start{heap_start} + , heap_end{heap_end} + , next{heap_start} + { + // Nothing to do + } + + auto allocate(std::size_t size) -> void * override; + + /** + * @copybrief heap_allocator::deallocate + * + * @note Simply does nothing, because this allocator leaks all memory + */ + auto deallocate(void * pointer) noexcept -> void override; + + private: + std::size_t heap_start; ///< Start of the allocatable heap area + std::size_t heap_end; ///< End of the allocatable heap area + std::atomic_uint64_t next; ///< Current address, which is the start of still unused allocatable heap area + }; + +} // namespace teachos::arch::memory::heap + +#endif // TEACHOS_ARCH_X86_64_MEMORY_HEAP_BUMP_ALLOCATOR_HPP diff --git a/arch/x86_64/pre/include/arch/memory/heap/global_heap_allocator.hpp b/arch/x86_64/pre/include/arch/memory/heap/global_heap_allocator.hpp new file mode 100644 index 0000000..480b1d0 --- /dev/null +++ b/arch/x86_64/pre/include/arch/memory/heap/global_heap_allocator.hpp @@ -0,0 +1,117 @@ +#ifndef TEACHOS_ARCH_X86_64_MEMORY_HEAP_GLOBAL_HEAP_ALLOCATOR_HPP +#define TEACHOS_ARCH_X86_64_MEMORY_HEAP_GLOBAL_HEAP_ALLOCATOR_HPP + +#include "arch/memory/heap/heap_allocator.hpp" +#include "arch/memory/heap/user_heap_allocator.hpp" + +namespace teachos::arch::memory::heap +{ + /** + * @brief Possible types that should be constructed by the register_heap_allocator factory method. + * Creates the underlying heap allocator instance that is then used by all global allocations using new and delete + */ + enum class heap_allocator_type : uint8_t + { + NONE, ///< Don't use any heap allocation implementation, this will result in all calls of new and delte halting + ///< further execution of the kernel + BUMP, ///< Use the bump allocator as the heap allocation implementation, be aware that using this allocator leaks + ///< memory, because there is no delete implementation + LINKED_LIST ///< Use the linked list allocator as the heap implementation, recommended because it does not leak + ///< memory + }; + + /** + * @brief Global instance of a heap allocator implementation created by the factory method pattern @see + * https://refactoring.guru/design-patterns/factory-method for more information. + * + * @note Can only be registered once and only once the kernel and the heap part of the kernel has been remapped + * successfully. If the instance is created before than the device will abort, because it acceses unmapped memory + * areas. + */ + struct global_heap_allocator + { + /** + * @brief Registers the heap allocation implementation that should be used by the global heap allocator. + * Meaning all future calls to the global new or delete will be forwarded to the allocate and deallocate calls of + * the underlying heap allocation implementation + * + * @param new_type Type of the heap allocation implementation we want to instantiate + */ + auto static register_heap_allocator(heap_allocator_type new_type) -> void; + + /** + * @brief Allocates the given amount of memory and returns the pointer to the start of the allocatable memory area. + * Simply forwards the call to the allocate method of the registered heap_allocation implementation + * + * @param size Amount of bytes that should be allocated + * @return void* Pointer to the start of the allocatable memory area + */ + auto static kmalloc(std::size_t size) -> void *; + + /** + * @brief Deallocated all memory associated with the memory area starting from the given pointer address. + * Simply forwards the call to the deallocate method of the registered heap_allocation implementation + * + * @param pointer Previously allocated memory area, that should now be freed + */ + auto static kfree(void * pointer) noexcept -> void; + + /** + * @brief Allocates the given amount of memory and returns the pointer to the start of the allocatable memory area. + * Simply forwards the call to the allocate method of the registered heap_allocation implementation + * + * @param size Amount of bytes that should be allocated + * @return void* Pointer to the start of the allocatable memory area + */ + [[gnu::section(".user_text")]] + auto static malloc(std::size_t size) -> void *; + + /** + * @brief Deallocated all memory associated with the memory area starting from the given pointer address. + * Simply forwards the call to the deallocate method of the registered heap_allocation implementation + * + * @param pointer Previously allocated memory area, that should now be freed + */ + [[gnu::section(".user_text")]] + auto static free(void * pointer) noexcept -> void; + + private: + heap_allocator static * kernel_allocator_instance; ///< Instance used to allocate and deallocate kernel heap memory + [[gnu::section(".user_data")]] user_heap_allocator static * + user_allocator_instance; ///< Instance used to allocate and deallocate user heap memory + + /** + * @brief Either returns the previously registered heap allocated or halts further execution + * + * @return Reference to the registered kernel heap allocation + */ + auto static kernel() -> heap_allocator &; + + /** + * @brief Either returns the previously registered heap allocated or halts further execution + * + * @return Reference to the registered user heap allocation + */ + [[gnu::section(".user_text")]] auto static user() -> user_heap_allocator &; + }; +} // namespace teachos::arch::memory::heap + +[[gnu::section(".user_text")]] +auto operator new(std::size_t size) -> void *; + +[[gnu::section(".user_text")]] +auto operator delete(void * pointer) noexcept -> void; + +[[gnu::section(".user_text")]] +auto operator delete(void * pointer, std::size_t size) noexcept -> void; + +[[gnu::section(".user_text")]] +auto operator new[](std::size_t size) -> void *; + +[[gnu::section(".user_text")]] +auto operator delete[](void * pointer) noexcept -> void; + +[[gnu::section(".user_text")]] +auto operator delete[](void * pointer, std::size_t size) noexcept -> void; + +#endif // TEACHOS_ARCH_X86_64_MEMORY_HEAP_GLOBAL_HEAP_ALLOCATOR_HPP diff --git a/arch/x86_64/pre/include/arch/memory/heap/heap_allocator.hpp b/arch/x86_64/pre/include/arch/memory/heap/heap_allocator.hpp new file mode 100644 index 0000000..6c25532 --- /dev/null +++ b/arch/x86_64/pre/include/arch/memory/heap/heap_allocator.hpp @@ -0,0 +1,45 @@ +#ifndef TEACHOS_ARCH_X86_64_MEMORY_HEAP_HEAP_ALLOCATOR_HPP +#define TEACHOS_ARCH_X86_64_MEMORY_HEAP_HEAP_ALLOCATOR_HPP + +#include <cstdint> + +namespace teachos::arch::memory::heap +{ + constexpr std::size_t KERNEL_HEAP_START = 0x1'0000'0000; + constexpr std::size_t KERNEL_HEAP_SIZE = 100 * 1024; + constexpr std::size_t USER_HEAP_START = 0x1'0001'9000; // Starts directly after kernel heap + constexpr std::size_t USER_HEAP_SIZE = 100 * 1024; + + /** + * @brief Heap allocator interface containing methods required to allocate and deallocate heap memory areas + */ + struct heap_allocator + { + /** + * @brief Virtual default destructor, created to ensure that if a pointer to this class is used and deleted, we will + * also call the derived base class destructor. Deleting a base class destructor that does not have a virtual + * destructor is undefined behaviour, because the derived class destructor originally instantiated with new is never + * called. This can cause potential memory leaks, because derived classes can not clean up their internal members as + * expected and instead simply leak them + */ + virtual ~heap_allocator() {} + + /** + * @brief Allocates the given amount of memory and returns the pointer to the start of the allocatable memory area + * + * @param size Amount of bytes that should be allocated + * @return void* Pointer to the start of the allocatable memory area + */ + virtual auto allocate(std::size_t size) -> void * = 0; + + /** + * @brief Deallocates all memory associated with the given pointer address. + * Simply deallocates the amount of memory created with the corresponding call to allocate + * + * @param pointer Previously allocated memory area, that should now be freed + */ + virtual auto deallocate(void * pointer) noexcept -> void = 0; + }; +} // namespace teachos::arch::memory::heap + +#endif // TEACHOS_ARCH_X86_64_MEMORY_HEAP_HEAP_ALLOCATOR_HPP diff --git a/arch/x86_64/pre/include/arch/memory/heap/linked_list_allocator.hpp b/arch/x86_64/pre/include/arch/memory/heap/linked_list_allocator.hpp new file mode 100644 index 0000000..bb8b526 --- /dev/null +++ b/arch/x86_64/pre/include/arch/memory/heap/linked_list_allocator.hpp @@ -0,0 +1,123 @@ +#ifndef TEACHOS_ARCH_X86_64_MEMORY_HEAP_LINKED_LIST_ALLOCATOR_HPP +#define TEACHOS_ARCH_X86_64_MEMORY_HEAP_LINKED_LIST_ALLOCATOR_HPP + +#include "arch/memory/heap/heap_allocator.hpp" +#include "arch/memory/heap/memory_block.hpp" + +#include <kstd/mutex.hpp> + +namespace teachos::arch::memory::heap +{ + /** + * @brief Sorted by address list of memory holes (free memory). Uses free holes itself to save the information, + * containing the size and pointer to the next hole. Resulting in a singly linked list. + */ + struct linked_list_allocator : heap_allocator + { + /** + * @brief Constructor. + * + * @param heap_start Start of the allocatable heap area + * @param heap_end End of the allocatable heap area (Start + Size) + */ + linked_list_allocator(std::size_t heap_start, std::size_t heap_end); + + /** + * @copybrief heap_allocator::allocate + * + * @note The specified size is used to find a free memory block with the exact same size, meaning we can remove that + * free memory block from the free list and simply return its address. Or it has to be big enough to hold the size + * and alteast enough memory for another free memory block entry (16 bytes). If the amount of memory of that free + * memory block is in between we cannot use it for our allocation, because we could only return it to the user, but + * the additional bytes, could not be used to create a free memory block. Additionaly the user couldn't know + * they received more memory than wanted. Therefore the memory would simply be unused and because it is neither + * allocated nor deallocated would never be indexed by the free memory list. We would therefore permanently loose + * that memory, to prevent that allocation into free memory blocks like that are impossible. + */ + auto allocate(std::size_t size) -> void * override; + + auto deallocate(void * pointer) noexcept -> void override; + + private: + /** + * @brief Returns the smallest allocatable block of heap memory. + * + * @return Smallest allocatable block of heap memory. + */ + constexpr auto min_allocatable_size() -> std::size_t + { + return sizeof(memory_block); + } + + /** + * @brief Removes a free memory block from the free list and returns its address so the caller can allocate into it. + * + * @param previous_block Free memory block before the block to allocate in our heap memory. Was to small to + * allocate the required size into. + * @param current_block Free memory block we want to remove from the free list and return for the allocation. + * + * @return Previous start address of the memory block we removed, because it can now be used for the allocation. + */ + auto remove_free_memory_block(memory_block * previous_block, memory_block * current_block) -> void *; + + /** + * @brief Splits the given free memory block into two, where the latter block keeps being free and the first + * part will be used for the allocation. + * + * @param previous_block Free memory block before the block to allocate in our heap memory. Was to small to + * allocate the required size into. + * @param current_block Free memory block we want to split into a size part for the allocation and the rest for + * future allocations. + * @param size Size we want to allocate at the start of the free memory block. + * + * @return Previous start address of the memory block we just split, because it can now be used for the allocation. + */ + auto split_free_memory_block(memory_block * previous_block, memory_block * current_block, std::size_t size) + -> void *; + + /** + * @brief Removes a free memory block from the free list and returns its address so the caller can allocate into it. + * + * @param previous_block Free memory block before the block to allocate in our heap memory. Was to small to + * allocate the required size into. + * @param current_block Free memory block we want to remove from the free list and return for the allocation. + * @param new_block Replaces the current block with the given new block can be nullptr, meaning the free list will + * end here. + * + * @return Previous start address of the memory block we removed, because it can now be used for the allocation. + */ + auto replace_free_memory_block(memory_block * previous_block, memory_block * current_block, + memory_block * new_block) -> void *; + + /** + * @brief Combines multiple free memory blocks into one if they are adjacent. + * + * @note The internal algorithm for recombination functions like this: + * 1. Check if there is even any memory left, if not the first entry of our linked list should be a nullptr and + * we can therefore set the first entry to our newly created entry. This entry is created in the now deallocated + * memory area. + * 2. If there are more blocks but neither the previous nor the current block are adjacent, we simply create a + * new free memory block of the given size and set the previous next to our block and the next of our block to + * the current block. + * 3. If the current block is adjacent the start address of the newly created block stays the same, but the size + * increases by the amount in the current memory block header. After reading it we also clear the header. + * 4. If the previous block is adjacent the size of the previous block simply increases to include the given + * size as well. + * 5. If the previous block is directly in our start address, so they overlap then it has to mean some or all of + * the region we are trying to deallocate has been freed before. Which would result in a double free therefore + * we halt the execution of the program. + * + * @param previous_block Free memory block before the block to deallocate in our heap memory. + * @param current_block Free memory block after the block to deallocate in our heap memory. + * @param pointer Block to deallocate. + * @param size Size of the block we want to deallocate. + */ + auto coalesce_free_memory_block(memory_block * previous_block, memory_block * current_block, void * pointer, + std::size_t size) -> void; + + memory_block * first; ///< First free entry in our memory. + kstd::mutex mutex; ///< Mutex to ensure only one thread calls allocate or deallocate at once. + }; +} // namespace teachos::arch::memory::heap + +#endif // TEACHOS_ARCH_X86_64_MEMORY_HEAP_LINKED_LIST_ALLOCATOR_HPP diff --git a/arch/x86_64/pre/include/arch/memory/heap/memory_block.hpp b/arch/x86_64/pre/include/arch/memory/heap/memory_block.hpp new file mode 100644 index 0000000..9d1fb02 --- /dev/null +++ b/arch/x86_64/pre/include/arch/memory/heap/memory_block.hpp @@ -0,0 +1,39 @@ +#ifndef TEACHOS_ARCH_X86_64_MEMORY_HEAP_MEMORY_BLOCK_HPP +#define TEACHOS_ARCH_X86_64_MEMORY_HEAP_MEMORY_BLOCK_HPP + +#include <cstdint> + +namespace teachos::arch::memory::heap +{ + /** + * @brief Block containing free memory, pointing to the next free hole (nullptr) if there is none. + * Forms a singly linked list of free memory blocks that we can callocate memory into. + */ + struct memory_block + { + /** + * @brief Constructor. Clears all memory from the place it was allocated until the end (address + + * size). + * + * @param size Amount of free memory of this specific hole. + * @param next Optional pointer to the next free memory. + */ + [[gnu::section(".user_text")]] + memory_block(std::size_t size, memory_block * next); + + /** + * @brief Destructor. Clears all internal memory. + * + * @note Used so the memory can be reused to construct other classes into, without having the old values. + * Required because we cannot call delete, because it causes "undefined reference to `sbrk`". + */ + [[gnu::section(".user_text")]] + ~memory_block(); + + std::size_t size; ///< Amount of free memory this hole contains, has to always be atleast 16 bytes to hold the + ///< size variable and the pointer to the next hole. + memory_block * next; ///< Optional pointer to the next free memory, holds nullptr if there is none. + }; +} // namespace teachos::arch::memory::heap + +#endif // TEACHOS_ARCH_X86_64_MEMORY_HEAP_MEMORY_BLOCK_HPP diff --git a/arch/x86_64/pre/include/arch/memory/heap/user_heap_allocator.hpp b/arch/x86_64/pre/include/arch/memory/heap/user_heap_allocator.hpp new file mode 100644 index 0000000..15d8574 --- /dev/null +++ b/arch/x86_64/pre/include/arch/memory/heap/user_heap_allocator.hpp @@ -0,0 +1,153 @@ +#ifndef TEACHOS_ARCH_X86_64_MEMORY_HEAP_USER_HEAP_ALLOCATOR_HPP +#define TEACHOS_ARCH_X86_64_MEMORY_HEAP_USER_HEAP_ALLOCATOR_HPP + +#include "arch/memory/heap/memory_block.hpp" + +// #include <kstd/mutex.hpp> +#include <kstd/mutex.hpp> + +#include <optional> + +namespace teachos::arch::memory::heap +{ + /** + * @brief Sorted by address list of memory holes (free memory). Uses free holes itself to save the information, + * containing the size and pointer to the next hole. Resulting in a singly linked list. + */ + struct user_heap_allocator + { + /** + * @brief Constructor. + */ + user_heap_allocator() = default; + + /** + * @copybrief heap_allocator::allocate + * + * @note The specified size is used to find a free memory block with the exact same size, meaning we can remove that + * free memory block from the free list and simply return its address. Or it has to be big enough to hold the size + * and alteast enough memory for another free memory block entry (16 bytes). If the amount of memory of that free + * memory block is in between we cannot use it for our allocation, because we could only return it to the user, but + * the additional bytes, could not be used to create a free memory block. Additionaly the user couldn't know + * they received more memory than wanted. Therefore the memory would simply be unused and because it is neither + * allocated nor deallocated would never be indexed by the free memory list. We would therefore permanently loose + * that memory, to prevent that allocation into free memory blocks like that are impossible. + */ + [[gnu::section(".user_text")]] + auto allocate(std::size_t size) -> void *; + + /** + * @copybrief heap_allocator::deallocate + */ + [[gnu::section(".user_text")]] + auto deallocate(void * pointer) noexcept -> void; + + private: + /** + * @brief Returns the smallest allocatable block of heap memory. + * + * @return Smallest allocatable block of heap memory. + */ + [[gnu::section(".user_text")]] constexpr auto min_allocatable_size() -> std::size_t + { + return sizeof(memory_block); + } + + /** + * @brief Checks if the given memory block is big enough and if it is allocates into the current block. + * + * @note Adjusts the link of the previous memory block to the new smaller remaining block. If the allocation used + * the complete block instead the previous block will point to the next block of the current memroy block that was + * used for the allocation. + * + * @return Allocated usable memory area. + */ + [[gnu::section(".user_text")]] auto + allocate_into_memory_block_if_big_enough(memory_block * current, memory_block * previous, std::size_t total_size) + -> std::optional<void *>; + + /** + * @brief Special functionality fo the user heap allocator. Which will result in it being expanded by a syscall with + * addtionally 100 KiB, which are mapped into the page table. Will always work until there is no physical memory + * left. + * + * @return Start of the newly with syscall allocated free memory block. Nullptr if the syscall failed. + */ + [[gnu::section(".user_text")]] auto expand_heap_if_full() -> memory_block *; + + /** + * @brief Removes a free memory block from the free list and returns its address so the caller can allocate into it. + * + * @param previous_block Free memory block before the block to allocate in our heap memory. Was to small to + * allocate the required size into. + * @param current_block Free memory block we want to remove from the free list and return for the allocation. + * + * @return Previous start address of the memory block we removed, because it can now be used for the allocation. + */ + [[gnu::section(".user_text")]] + auto remove_free_memory_block(memory_block * previous_block, memory_block * current_block) -> void *; + + /** + * @brief Splits the given free memory block into two, where the latter block keeps being free and the first + * part will be used for the allocation. + * + * @param previous_block Free memory block before the block to allocate in our heap memory. Was to small to + * allocate the required size into. + * @param current_block Free memory block we want to split into a size part for the allocation and the rest for + * future allocations. + * @param size Size we want to allocate at the start of the free memory block. + * + * @return Previous start address of the memory block we just split, because it can now be used for the allocation. + */ + [[gnu::section(".user_text")]] + auto split_free_memory_block(memory_block * previous_block, memory_block * current_block, std::size_t size) + -> void *; + + /** + * @brief Removes a free memory block from the free list and returns its address so the caller can allocate into it. + * + * @param previous_block Free memory block before the block to allocate in our heap memory. Was to small to + * allocate the required size into. + * @param current_block Free memory block we want to remove from the free list and return for the allocation. + * @param new_block Replaces the current block with the given new block can be nullptr, meaning the free list will + * end here. + * + * @return Previous start address of the memory block we removed, because it can now be used for the allocation. + */ + [[gnu::section(".user_text")]] + auto replace_free_memory_block(memory_block * previous_block, memory_block * current_block, + memory_block * new_block) -> void *; + + /** + * @brief Combines multiple free memory blocks into one if they are adjacent. + * + * @note The internal algorithm for recombination functions like this: + * 1. Check if there is even any memory left, if not the first entry of our linked list should be a nullptr and + * we can therefore set the first entry to our newly created entry. This entry is created in the now deallocated + * memory area. + * 2. If there are more blocks but neither the previous nor the current block are adjacent, we simply create a + * new free memory block of the given size and set the previous next to our block and the next of our block to + * the current block. + * 3. If the current block is adjacent the start address of the newly created block stays the same, but the size + * increases by the amount in the current memory block header. After reading it we also clear the header. + * 4. If the previous block is adjacent the size of the previous block simply increases to include the given + * size as well. + * 5. If the previous block is directly in our start address, so they overlap then it has to mean some or all of + * the region we are trying to deallocate has been freed before. Which would result in a double free therefore + * we halt the execution of the program. + * + * @param previous_block Free memory block before the block to deallocate in our heap memory. + * @param current_block Free memory block after the block to deallocate in our heap memory. + * @param pointer Block to deallocate. + * @param size Size of the block we want to deallocate. + */ + [[gnu::section(".user_text")]] + auto coalesce_free_memory_block(memory_block * previous_block, memory_block * current_block, void * pointer, + std::size_t size) -> void; + + memory_block * first = {}; ///< First free entry in our memory. + kstd::mutex mutex = {}; ///< Mutex to ensure only one thread calls allocate or deallocate at once. + }; +} // namespace teachos::arch::memory::heap + +#endif // TEACHOS_ARCH_X86_64_MEMORY_HEAP_USER_HEAP_ALLOCATOR_HPP diff --git a/arch/x86_64/pre/include/arch/user/main.hpp b/arch/x86_64/pre/include/arch/user/main.hpp new file mode 100644 index 0000000..c168a1f --- /dev/null +++ b/arch/x86_64/pre/include/arch/user/main.hpp @@ -0,0 +1,16 @@ +#ifndef TEACHOS_ARCH_X86_64_USER_MAIN_HPP +#define TEACHOS_ARCH_X86_64_USER_MAIN_HPP + +namespace teachos::arch::user +{ + /** + * @brief User Main method. If this method finishes there is no code left to run and the whole OS will shut down. + * Additionally this main method is executed at Ring 3 and accessing CPU Registers or Kernel level functionality can + * only be done over syscalls and not directly anymore. + */ + [[gnu::section(".user_text")]] + auto main() -> void; + +} // namespace teachos::arch::user + +#endif // TEACHOS_ARCH_X86_64_USER_MAIN_HPP diff --git a/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/gate_descriptor.cpp b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/gate_descriptor.cpp new file mode 100644 index 0000000..28f289c --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/gate_descriptor.cpp @@ -0,0 +1,24 @@ +#include "arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + gate_descriptor::gate_descriptor(uint128_t flags) + : _offset_1(flags) + , _selector(flags >> 19U, flags >> 16U) + , _ist(flags >> 32U) + , _flags(flags >> 40U) + , _offset_2(flags >> 48U) + { + // Nothing to do. + } + + gate_descriptor::gate_descriptor(segment_selector selector, ist_offset ist, idt_flags flags, uint64_t offset) + : _offset_1(offset) + , _selector(selector) + , _ist(ist) + , _flags(flags) + , _offset_2(offset >> 16U) + { + // Nothing to do. + } +} // namespace teachos::arch::context_switching::interrupt_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/idt_flags.cpp b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/idt_flags.cpp new file mode 100644 index 0000000..f3b9d5e --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/idt_flags.cpp @@ -0,0 +1,20 @@ +#include "arch/context_switching/interrupt_descriptor_table/idt_flags.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + idt_flags::idt_flags(uint8_t flags) + : _flags(flags) + { + // Nothing to do. + } + + auto idt_flags::contains_flags(std::bitset<8U> other) const -> bool + { + return (std::bitset<8U>{_flags} & other) == other; + } + + auto idt_flags::operator|=(std::bitset<8U> other) -> void + { + _flags |= other.to_ulong(); + } +} // namespace teachos::arch::context_switching::interrupt_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp new file mode 100644 index 0000000..8640385 --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp @@ -0,0 +1,53 @@ +#include "arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp" + +#include "arch/exception_handling/assert.hpp" +#include "arch/interrupt_handling/generic_interrupt_handler.hpp" +#include "arch/kernel/cpu/idtr.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + namespace + { + /// @brief Amount of currently reserved interrupt indicies. + /// See https://wiki.osdev.org/Interrupt_Descriptor_Table#IDT_items for more information. + constexpr uint16_t RESERVED_INTERRUPT_COUNT = 256U; + + auto create_interrupt_descriptor_table() -> interrupt_descriptor_table + { + interrupt_descriptor_table interrupt_descriptor_table{RESERVED_INTERRUPT_COUNT}; + + uint64_t offset = reinterpret_cast<uint64_t>(interrupt_handling::generic_interrupt_handler); + segment_selector selector{1U, segment_selector::REQUEST_LEVEL_KERNEL}; + ist_offset ist{0U}; + idt_flags flags{idt_flags::DESCRIPTOR_LEVEL_KERNEL | idt_flags::INTERRUPT_GATE | idt_flags::PRESENT}; + + for (std::size_t i = 0; i < interrupt_descriptor_table.size(); i++) + { + interrupt_descriptor_table.at(i) = {selector, ist, flags, offset}; + } + + return interrupt_descriptor_table; + } + } // namespace + + auto get_or_create_interrupt_descriptor_table() -> interrupt_descriptor_table & + { + // Interrupt Descriptor Table needs to be kept alive + interrupt_descriptor_table static idt = create_interrupt_descriptor_table(); + return idt; + } + + auto update_interrupt_descriptor_table_register() -> void + { + decltype(auto) idt = get_or_create_interrupt_descriptor_table(); + + interrupt_descriptor_table_pointer idt_pointer{static_cast<uint16_t>((idt.size() * sizeof(gate_descriptor)) - 1), + idt.data()}; + kernel::cpu::load_interrupt_descriptor_table(idt_pointer); + + auto const stored_gdt_pointer = kernel::cpu::store_interrupt_descriptor_table(); + arch::exception_handling::assert( + idt_pointer == stored_gdt_pointer, + "[Interrupt Descriptor Table] Loaded IDTR value is not the same as the stored value."); + } +} // namespace teachos::arch::context_switching::interrupt_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.cpp b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.cpp new file mode 100644 index 0000000..7bcbae6 --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.cpp @@ -0,0 +1,13 @@ +#include "arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + interrupt_descriptor_table_pointer::interrupt_descriptor_table_pointer(uint16_t table_length, + gate_descriptor * address) + : table_length(table_length) + , address(address) + { + // Nothing to do. + } + +} // namespace teachos::arch::context_switching::interrupt_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/ist_offset.cpp b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/ist_offset.cpp new file mode 100644 index 0000000..a70e75d --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/ist_offset.cpp @@ -0,0 +1,10 @@ +#include "arch/context_switching/interrupt_descriptor_table/ist_offset.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + ist_offset::ist_offset(uint8_t index) + : _ist(index) + { + // Nothing to do. + } +} // namespace teachos::arch::context_switching::interrupt_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/segment_selector.cpp b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/segment_selector.cpp new file mode 100644 index 0000000..25ba859 --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/interrupt_descriptor_table/segment_selector.cpp @@ -0,0 +1,24 @@ +#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp" + +namespace teachos::arch::context_switching::interrupt_descriptor_table +{ + auto segment_selector::contains_flags(std::bitset<3U> other) const -> bool + { + return (std::bitset<3U>{_flags} & other) == other; + } + + auto segment_selector::get_index() const -> uint16_t + { + return _index; + } + + auto segment_selector::operator|=(std::bitset<3U> other) -> void + { + _flags |= other.to_ulong(); + } + + segment_selector::operator uint16_t() const + { + return *reinterpret_cast<uint16_t const *>(this); + } +} // namespace teachos::arch::context_switching::interrupt_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/main.cpp b/arch/x86_64/pre/src/context_switching/main.cpp new file mode 100644 index 0000000..3eb6dae --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/main.cpp @@ -0,0 +1,66 @@ +#include "arch/context_switching/main.hpp" + +#include "arch/boot/pointers.hpp" +#include "arch/context_switching/syscall/syscall_enable.hpp" +#include "arch/kernel/cpu/call.hpp" +#include "arch/kernel/cpu/if.hpp" +#include "arch/kernel/cpu/segment_register.hpp" +#include "arch/kernel/cpu/tr.hpp" +#include "arch/user/main.hpp" + +namespace teachos::arch::context_switching +{ + namespace + { + constexpr interrupt_descriptor_table::segment_selector KERNEL_CODE_SEGMENT_SELECTOR{ + 1U, interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_KERNEL}; + constexpr kernel::cpu::far_pointer KERNEL_CODE_POINTER{&kernel::cpu::reload_data_segment_registers, + KERNEL_CODE_SEGMENT_SELECTOR}; + constexpr context_switching::interrupt_descriptor_table::segment_selector USER_CODE_SEGMENT_SELECTOR{ + 3U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER}; + constexpr context_switching::interrupt_descriptor_table::segment_selector USER_DATA_SEGMENT_SELECTOR{ + 4U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER}; + + auto reload_gdtr() -> void + { + kernel::cpu::call(KERNEL_CODE_POINTER); + } + } // namespace + + auto initialize_descriptor_tables() -> descriptor_tables + { + bool static initalized = false; + + if (!initalized) + { + kernel::cpu::clear_interrupt_flag(); + + segment_descriptor_table::update_gdtr(); + interrupt_descriptor_table::update_interrupt_descriptor_table_register(); + + reload_gdtr(); + segment_descriptor_table::update_tss_register(); + + kernel::cpu::set_interrupt_flag(); + initalized = true; + } + + descriptor_tables tables = {segment_descriptor_table::get_or_create_gdt(), + interrupt_descriptor_table::get_or_create_interrupt_descriptor_table()}; + return tables; + } + + auto switch_to_user_mode() -> void + { + syscall::enable_syscall(); + switch_context(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR, user::main); + } + + auto switch_context(interrupt_descriptor_table::segment_selector data_segment, + interrupt_descriptor_table::segment_selector code_segment, void (*return_function)()) -> void + { + (void)initialize_descriptor_tables(); + kernel::cpu::set_data_segment_registers(data_segment); + kernel::cpu::set_code_segment_register(data_segment, code_segment, reinterpret_cast<uint64_t>(return_function)); + } +} // namespace teachos::arch::context_switching diff --git a/arch/x86_64/pre/src/context_switching/segment_descriptor_table/access_byte.cpp b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/access_byte.cpp new file mode 100644 index 0000000..fcc72cf --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/access_byte.cpp @@ -0,0 +1,20 @@ +#include "arch/context_switching/segment_descriptor_table/access_byte.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + access_byte::access_byte(uint8_t flags) + : _flags(flags) + { + // Nothing to do. + } + + auto access_byte::contains_flags(std::bitset<8U> other) const -> bool + { + return (std::bitset<8U>{_flags} & other) == other; + } + + auto access_byte::operator|=(std::bitset<8U> other) -> void + { + _flags |= other.to_ulong(); + } +} // namespace teachos::arch::context_switching::segment_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/segment_descriptor_table/gdt_flags.cpp b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/gdt_flags.cpp new file mode 100644 index 0000000..ad1366a --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/gdt_flags.cpp @@ -0,0 +1,26 @@ +#include "arch/context_switching/segment_descriptor_table/gdt_flags.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + gdt_flags::gdt_flags(uint8_t flags, std::bitset<20U> limit) + : _limit_2(limit.to_ulong() >> 16U) + , _flags(flags) + { + // Nothing to do. + } + + auto gdt_flags::contains_flags(std::bitset<4U> other) const -> bool + { + return (std::bitset<4U>{_flags} & other) == other; + } + + auto gdt_flags::get_limit() const -> std::bitset<4U> + { + return std::bitset<4U>{_limit_2}; + } + + auto gdt_flags::operator|=(std::bitset<4U> other) -> void + { + _flags |= other.to_ulong(); + } +} // namespace teachos::arch::context_switching::segment_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/segment_descriptor_table/global_descriptor_table.cpp b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/global_descriptor_table.cpp new file mode 100644 index 0000000..1c4729f --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/global_descriptor_table.cpp @@ -0,0 +1,109 @@ +#include "arch/context_switching/segment_descriptor_table/global_descriptor_table.hpp" + +#include "arch/context_switching/segment_descriptor_table/segment_descriptor_extension.hpp" +#include "arch/exception_handling/assert.hpp" +#include "arch/kernel/cpu/gdtr.hpp" +#include "arch/kernel/cpu/tr.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + namespace + { + auto create_segment_descriptor(segment_descriptor_type segment_descriptor_type, access_byte access_level) + -> segment_descriptor_base + { + constexpr uint64_t BASE = 0x0; + constexpr std::bitset<20U> LIMIT{0xFFFFF}; + gdt_flags flags{gdt_flags::GRANULARITY, LIMIT}; + + access_level |= access_byte::PRESENT | access_byte::CODE_OR_DATA_SEGMENT; + if (segment_descriptor_type == segment_descriptor_type::CODE_SEGMENT) + { + flags |= gdt_flags::LONG_MODE; + access_level |= access_byte::CODE_SEGMENT | access_byte::READABLE; + } + else if (segment_descriptor_type == segment_descriptor_type::DATA_SEGMENT) + { + access_level |= access_byte::WRITABLE; + } + + segment_descriptor_base const segment_descriptor_base{access_level, flags, BASE, LIMIT}; + return segment_descriptor_base; + } + + auto create_tss_descriptor(task_state_segment * tss) -> segment_descriptor_extension + { + constexpr uint64_t TSS_LIMIT = sizeof(task_state_segment) - 1; + access_byte const tss_access_byte{access_byte::PRESENT | access_byte::DESCRIPTOR_LEVEL_KERNEL | + access_byte::TASK_STATE_SEGMENT_AVAILABLE}; + gdt_flags const tss_gdt_flags{0U, TSS_LIMIT}; + segment_descriptor_extension const tss_descriptor{tss_access_byte, tss_gdt_flags, reinterpret_cast<uint64_t>(tss), + TSS_LIMIT}; + return tss_descriptor; + } + + auto create_gdt() -> global_descriptor_table + { + segment_descriptor_base const null_segment{0}; + segment_descriptor_base const kernel_code_segment = + create_segment_descriptor(segment_descriptor_type::CODE_SEGMENT, access_byte::DESCRIPTOR_LEVEL_KERNEL); + segment_descriptor_base const kernel_data_segment = + create_segment_descriptor(segment_descriptor_type::DATA_SEGMENT, access_byte::DESCRIPTOR_LEVEL_KERNEL); + segment_descriptor_base const user_code_segment = + create_segment_descriptor(segment_descriptor_type::CODE_SEGMENT, access_byte::DESCRIPTOR_LEVEL_USER); + segment_descriptor_base const user_data_segment = + create_segment_descriptor(segment_descriptor_type::DATA_SEGMENT, access_byte::DESCRIPTOR_LEVEL_USER); + + // Task State Segment needs to be kept alive + auto static tss = new task_state_segment(); + segment_descriptor_extension const tss_descriptor = create_tss_descriptor(tss); + + global_descriptor_table global_descriptor_table{null_segment, + kernel_code_segment, + kernel_data_segment, + user_code_segment, + user_data_segment, + tss_descriptor.get_first_gdt_entry(), + tss_descriptor.get_second_gdt_entry()}; + return global_descriptor_table; + } + } // namespace + + auto get_or_create_gdt() -> global_descriptor_table & + { + // Global Descriptor Table needs to be kept alive + global_descriptor_table static gdt = create_gdt(); + return gdt; + } + + auto update_gdtr() -> void + { + decltype(auto) gdt = get_or_create_gdt(); + + // Calculate the size of the gdt in bytes - 1. This subtraction occurs because the maximum value of Size is 65535, + // while the GDT can be up to 65536 bytes in length (8192 entries). Further, no GDT can have a size of 0 bytes. + uint16_t gdt_size = static_cast<uint16_t>((gdt.size() * sizeof(segment_descriptor_base)) - 1); + global_descriptor_table_pointer gdt_pointer{gdt_size, gdt.data()}; + kernel::cpu::load_global_descriptor_table(gdt_pointer); + + auto const stored_gdt_pointer = kernel::cpu::store_global_descriptor_table(); + arch::exception_handling::assert( + gdt_pointer == stored_gdt_pointer, + "[Global Descriptor Table] Loaded GDTR value is not the same as the stored value."); + } + + auto update_tss_register() -> void + { + decltype(auto) gdt = get_or_create_gdt(); + + // Load task state segment descriptor from the last element in the global descriptor table, done by calculating + // offset in bytes to the start of the segment descriptor (5 * 8) = 40 + uint16_t tss_selector = (gdt.size() * sizeof(segment_descriptor_base)) - sizeof(segment_descriptor_extension); + kernel::cpu::load_task_register(tss_selector); + + auto const stored_task_register = kernel::cpu::store_task_register(); + arch::exception_handling::assert(tss_selector == stored_task_register, + "[Global Descriptor Table] Loaded TR value is not the same as the stored value."); + } + +} // namespace teachos::arch::context_switching::segment_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/segment_descriptor_table/global_descriptor_table_pointer.cpp b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/global_descriptor_table_pointer.cpp new file mode 100644 index 0000000..79088b8 --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/global_descriptor_table_pointer.cpp @@ -0,0 +1,11 @@ +#include "arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + global_descriptor_table_pointer::global_descriptor_table_pointer(uint16_t table_length, uint64_t * address) + : table_length(table_length) + , address(address) + { + // Nothing to do. + } +} // namespace teachos::arch::context_switching::segment_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/segment_descriptor_table/segment_descriptor_base.cpp b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/segment_descriptor_base.cpp new file mode 100644 index 0000000..c3a03fc --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/segment_descriptor_base.cpp @@ -0,0 +1,41 @@ +#include "arch/context_switching/segment_descriptor_table/segment_descriptor_base.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + segment_descriptor_base::segment_descriptor_base(uint64_t flags) + : _limit_1(flags) + , _base_1(flags >> 16U) + , _access(flags >> 40U) + , _flag(flags >> 52U, flags >> 48U) + , _base_2(flags >> 56U) + { + // Nothing to do. + } + + segment_descriptor_base::segment_descriptor_base(access_byte access_byte, gdt_flags flags, uint32_t base, + std::bitset<20U> limit) + : _limit_1(limit.to_ulong()) + , _base_1(base) + , _access(access_byte) + , _flag(flags) + , _base_2(base >> 24U) + { + // Nothing to do + } + + auto segment_descriptor_base::get_segment_type() const -> segment_descriptor_type + { + if (!_access.contains_flags(access_byte::CODE_OR_DATA_SEGMENT)) + { + return segment_descriptor_type::SYSTEM_SEGMENT; + } + return _access.contains_flags(access_byte::CODE_SEGMENT) ? segment_descriptor_type::CODE_SEGMENT + : segment_descriptor_type::DATA_SEGMENT; + } + + segment_descriptor_base::operator uint64_t() const + { + return *reinterpret_cast<uint64_t const *>(this); + } + +} // namespace teachos::arch::context_switching::segment_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/segment_descriptor_table/segment_descriptor_extension.cpp b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/segment_descriptor_extension.cpp new file mode 100644 index 0000000..5ea0d8a --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/segment_descriptor_table/segment_descriptor_extension.cpp @@ -0,0 +1,30 @@ +#include "arch/context_switching/segment_descriptor_table/segment_descriptor_extension.hpp" + +namespace teachos::arch::context_switching::segment_descriptor_table +{ + segment_descriptor_extension::segment_descriptor_extension(uint128_t flags) + : _base(flags) + , _base_3(flags >> 64U) + { + // Nothing to do. + } + + segment_descriptor_extension::segment_descriptor_extension(access_byte access_byte, gdt_flags flags, uint64_t base, + std::bitset<20U> limit) + : _base(access_byte, flags, base, limit) + , _base_3(base >> 32U) + { + // Nothing to do + } + + auto segment_descriptor_extension::get_first_gdt_entry() const -> segment_descriptor_base + { + return _base; + } + + auto segment_descriptor_extension::get_second_gdt_entry() const -> uint64_t + { + return _base_3; + } + +} // namespace teachos::arch::context_switching::segment_descriptor_table diff --git a/arch/x86_64/pre/src/context_switching/syscall/main.cpp b/arch/x86_64/pre/src/context_switching/syscall/main.cpp new file mode 100644 index 0000000..b4ab468 --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/syscall/main.cpp @@ -0,0 +1,35 @@ +#include "arch/context_switching/syscall/main.hpp" + +namespace teachos::arch::context_switching::syscall +{ + auto syscall(type syscall_number, arguments args) -> response + { + asm volatile("mov %[input], %%rax" + : /* no output from call */ + : [input] "m"(syscall_number) + : "memory"); + + asm volatile("mov %[input], %%rdi " : /* no output from call */ : [input] "m"(args.arg_0) : "memory"); + asm volatile("mov %[input], %%rsi" : /* no output from call */ : [input] "m"(args.arg_1) : "memory"); + asm volatile("mov %[input], %%rdx" : /* no output from call */ : [input] "m"(args.arg_2) : "memory"); + asm volatile("mov %[input], %%r10" : /* no output from call */ : [input] "m"(args.arg_3) : "memory"); + asm volatile("mov %[input], %%r8" : /* no output from call */ : [input] "m"(args.arg_4) : "memory"); + asm volatile("mov %[input], %%r9" : /* no output from call */ : [input] "m"(args.arg_5) : "memory"); + + asm volatile("syscall"); + + arguments values{}; + asm volatile("mov %%rdi, %[output]" : [output] "=m"(values.arg_0)); + asm volatile("mov %%rsi, %[output]" : [output] "=m"(values.arg_1)); + asm volatile("mov %%rdx, %[output]" : [output] "=m"(values.arg_2)); + asm volatile("mov %%r10, %[output]" : [output] "=m"(values.arg_3)); + asm volatile("mov %%r8, %[output]" : [output] "=m"(values.arg_4)); + asm volatile("mov %%r9, %[output]" : [output] "=m"(values.arg_5)); + + error error_code{}; + asm volatile("mov %%al, %[output]" : [output] "=m"(error_code)); + + return {error_code, values}; + } + +} // namespace teachos::arch::context_switching::syscall diff --git a/arch/x86_64/pre/src/context_switching/syscall/syscall_enable.cpp b/arch/x86_64/pre/src/context_switching/syscall/syscall_enable.cpp new file mode 100644 index 0000000..dbb3ed9 --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/syscall/syscall_enable.cpp @@ -0,0 +1,32 @@ +#include "arch/context_switching/syscall/syscall_enable.hpp" + +#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp" +#include "arch/context_switching/syscall/syscall_handler.hpp" +#include "arch/kernel/cpu/msr.hpp" + +namespace teachos::arch::context_switching::syscall +{ + namespace + { + constexpr interrupt_descriptor_table::segment_selector KERNEL_CODE_SEGMENT_SELECTOR{ + 1U, interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_KERNEL}; + + constexpr auto IA32_STAR_ADDRESS = 0xC000'0081; + constexpr auto IA32_LSTAR_ADDRESS = 0xC000'0082; + constexpr auto IA32_FMASK_ADDRESS = 0xC000'0084; + + } // namespace + + auto enable_syscall() -> void + { + uint64_t const syscall_function = reinterpret_cast<uint64_t>(syscall_handler); + kernel::cpu::write_msr(IA32_LSTAR_ADDRESS, syscall_function); + kernel::cpu::write_msr(IA32_FMASK_ADDRESS, 0U); + + uint64_t const kernel_cs = KERNEL_CODE_SEGMENT_SELECTOR; + uint64_t const star_value = (kernel_cs << 32) | (kernel_cs << 48); + kernel::cpu::write_msr(IA32_STAR_ADDRESS, star_value); + + kernel::cpu::set_efer_bit(kernel::cpu::efer_flags::SCE); + } +} // namespace teachos::arch::context_switching::syscall diff --git a/arch/x86_64/pre/src/context_switching/syscall/syscall_handler.cpp b/arch/x86_64/pre/src/context_switching/syscall/syscall_handler.cpp new file mode 100644 index 0000000..c120f77 --- /dev/null +++ b/arch/x86_64/pre/src/context_switching/syscall/syscall_handler.cpp @@ -0,0 +1,121 @@ +#include "arch/context_switching/syscall/syscall_handler.hpp" + +#include "arch/context_switching/syscall/main.hpp" +#include "arch/exception_handling/assert.hpp" +#include "arch/exception_handling/panic.hpp" +#include "arch/memory/heap/global_heap_allocator.hpp" +#include "arch/memory/main.hpp" +#include "arch/video/vga/text.hpp" + +namespace teachos::arch::context_switching::syscall +{ + + namespace + { + auto write_to_vga_buffer(uint64_t buffer) -> response + { + video::vga::text::write(reinterpret_cast<char const *>(buffer), + video::vga::text::common_attributes::green_on_black); + video::vga::text::newline(); + return {error::OK}; + } + + auto expand_user_heap() -> response + { + auto static current_heap_end = memory::heap::USER_HEAP_START; + uint64_t const heap_start = current_heap_end; + memory::remap_heap(heap_start, memory::heap::USER_HEAP_SIZE, memory::paging::entry::USER_ACCESSIBLE); + current_heap_end += memory::heap::USER_HEAP_SIZE; + return { + error::OK, + {heap_start, memory::heap::USER_HEAP_SIZE} + }; + } + } // namespace + + auto syscall_handler() -> void + { + // Saving state of rcx and r11 because it is required by sysretq to function. + // Calls to other functions potentially overwrite these registers, because of + // callee saved calling convention. + uint64_t return_instruction_pointer, rflags = {}; + asm volatile("mov %%rcx, %[output]" : [output] "=m"(return_instruction_pointer)); + asm volatile("mov %%r11, %[output]" : [output] "=m"(rflags)); + + uint64_t syscall_number, arg_0, arg_1, arg_2, arg_3, arg_4, arg_5 = {}; + asm volatile("mov %%rdi, %[output]" : [output] "=m"(arg_0)); + asm volatile("mov %%rsi, %[output]" : [output] "=m"(arg_1)); + asm volatile("mov %%rdx, %[output]" : [output] "=m"(arg_2)); + asm volatile("mov %%r10, %[output]" : [output] "=m"(arg_3)); + asm volatile("mov %%r8, %[output]" : [output] "=m"(arg_4)); + asm volatile("mov %%r9, %[output]" : [output] "=m"(arg_5)); + + // RAX is read last, because paired with our type enum, we can use it to check + // if the register has been written by the compiled code between executing the syscall + // and now. + asm volatile("mov %%rax, %[output]" : [output] "=m"(syscall_number)); + + response result; + switch (static_cast<type>(syscall_number)) + { + case type::WRITE: + result = write_to_vga_buffer(arg_0); + break; + case type::EXPAND_HEAP: + result = expand_user_heap(); + break; + case type::ASSERT: + teachos::arch::exception_handling::assert(arg_0, reinterpret_cast<char const *>(arg_1)); + break; + default: + teachos::arch::exception_handling::panic("[Syscall Handler] Invalid syscall number"); + break; + } + + asm volatile("mov %[input], %%rax" + : /* no output from call */ + : [input] "m"(result.error_code) + : "memory"); + + asm volatile("mov %[input], %%rdi" + : /* no output from call */ + : [input] "m"(result.values.arg_0) + : "memory"); + asm volatile("mov %[input], %%rsi" + : /* no output from call */ + : [input] "m"(result.values.arg_1) + : "memory"); + asm volatile("mov %[input], %%rdx" + : /* no output from call */ + : [input] "m"(result.values.arg_2) + : "memory"); + asm volatile("mov %[input], %%r10" + : /* no output from call */ + : [input] "m"(result.values.arg_3) + : "memory"); + asm volatile("mov %[input], %%r8" + : /* no output from call */ + : [input] "m"(result.values.arg_4) + : "memory"); + asm volatile("mov %[input], %%r9" + : /* no output from call */ + : [input] "m"(result.values.arg_5) + : "memory"); + + asm volatile("mov %[input], %%rcx" + : /* no output from call */ + : [input] "m"(return_instruction_pointer) + : "memory"); + asm volatile("mov %[input], %%r11" + : /* no output from call */ + : [input] "m"(rflags) + : "memory"); + + // Additionally call leave, because x86 allocates stack space for the internal variables. If we do not clean up this + // newly created stack frame the syscall instruction that landed in this syscall_handler, will never return to the + // method that originally called it, because the RIP has not been restored from the previous stack frame. + asm volatile("leave\n" + "sysretq"); + } + +} // namespace teachos::arch::context_switching::syscall diff --git a/arch/x86_64/pre/src/exception_handling/abort.cpp b/arch/x86_64/pre/src/exception_handling/abort.cpp new file mode 100644 index 0000000..5dc6869 --- /dev/null +++ b/arch/x86_64/pre/src/exception_handling/abort.cpp @@ -0,0 +1,18 @@ +#include "arch/exception_handling/panic.hpp" + +#include <cstdlib> + +namespace teachos::arch::exception_handling +{ + /** + * @brief Override for the newlib abort function. + * + * @note newlib defines @p ::abort as a weak symbol, thus allowing implementations to override it by simply providing + * a matching implementation. Since the default implemenatation calls a number of functions the kernel does not + * currently implement, @p ::abort gets overridden to simply panic. + */ + extern "C" auto abort() -> void + { + panic("Terminate was called, possibly due to an unhandled exception"); + } +} // namespace teachos::arch::exception_handling diff --git a/arch/x86_64/pre/src/exception_handling/assert.cpp b/arch/x86_64/pre/src/exception_handling/assert.cpp new file mode 100644 index 0000000..b2963de --- /dev/null +++ b/arch/x86_64/pre/src/exception_handling/assert.cpp @@ -0,0 +1,15 @@ +#include "arch/exception_handling/assert.hpp" + +#include "arch/exception_handling/panic.hpp" + +namespace teachos::arch::exception_handling +{ + auto assert(bool condition, char const * message) -> void + { + if (condition) + { + return; + } + panic("Assertion Violation: ", message); + } +} // namespace teachos::arch::exception_handling diff --git a/arch/x86_64/pre/src/exception_handling/panic.cpp b/arch/x86_64/pre/src/exception_handling/panic.cpp new file mode 100644 index 0000000..9511a9a --- /dev/null +++ b/arch/x86_64/pre/src/exception_handling/panic.cpp @@ -0,0 +1,25 @@ +#include "arch/exception_handling/panic.hpp" + +#include "arch/kernel/halt.hpp" +#include "arch/video/vga/text.hpp" + +namespace teachos::arch::exception_handling +{ + extern "C" char const message_prefix_panic[]; + + auto panic(char const * reason) -> void + { + panic(message_prefix_panic, reason); + } + + auto panic(char const * prefix, char const * reason) -> void + { + using video::vga::text::common_attributes::white_on_red; + + video::vga::text::newline(); + video::vga::text::write(prefix, white_on_red); + video::vga::text::write(reason, white_on_red); + + kernel::halt(); + }; +} // namespace teachos::arch::exception_handling diff --git a/arch/x86_64/pre/src/exception_handling/pure_virtual.cpp b/arch/x86_64/pre/src/exception_handling/pure_virtual.cpp new file mode 100644 index 0000000..67772f7 --- /dev/null +++ b/arch/x86_64/pre/src/exception_handling/pure_virtual.cpp @@ -0,0 +1,6 @@ +#include "arch/exception_handling/panic.hpp" + +extern "C" auto __cxa_pure_virtual() -> void +{ + teachos::arch::exception_handling::panic("Runtime", "Tried to call a pure virtual function!"); +} diff --git a/arch/x86_64/pre/src/interrupt_handling/generic_interrupt_handler.cpp b/arch/x86_64/pre/src/interrupt_handling/generic_interrupt_handler.cpp new file mode 100644 index 0000000..9d061a8 --- /dev/null +++ b/arch/x86_64/pre/src/interrupt_handling/generic_interrupt_handler.cpp @@ -0,0 +1,13 @@ +#include "arch/interrupt_handling/generic_interrupt_handler.hpp" + +#include "arch/video/vga/text.hpp" + +namespace teachos::arch::interrupt_handling +{ + auto generic_interrupt_handler(interrupt_frame * frame) -> void + { + (void)frame; + video::vga::text::write("An Interrupt occurred.", video::vga::text::common_attributes::green_on_black); + video::vga::text::newline(); + } +} // namespace teachos::arch::interrupt_handling diff --git a/arch/x86_64/pre/src/kernel/cpu/call.cpp b/arch/x86_64/pre/src/kernel/cpu/call.cpp new file mode 100644 index 0000000..98fa248 --- /dev/null +++ b/arch/x86_64/pre/src/kernel/cpu/call.cpp @@ -0,0 +1,9 @@ +#include "arch/kernel/cpu/call.hpp" + +namespace teachos::arch::kernel::cpu +{ + auto call(far_pointer pointer) -> void + { + asm volatile("rex64 lcall *%[input]" : /* no output from call */ : [input] "m"(pointer)); + } +} // namespace teachos::arch::kernel::cpu diff --git a/arch/x86_64/pre/src/kernel/cpu/gdtr.cpp b/arch/x86_64/pre/src/kernel/cpu/gdtr.cpp new file mode 100644 index 0000000..74a4e1c --- /dev/null +++ b/arch/x86_64/pre/src/kernel/cpu/gdtr.cpp @@ -0,0 +1,19 @@ +#include "arch/kernel/cpu/gdtr.hpp" + +#include "arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp" + +namespace teachos::arch::kernel::cpu +{ + auto store_global_descriptor_table() -> context_switching::segment_descriptor_table::global_descriptor_table_pointer + { + context_switching::segment_descriptor_table::global_descriptor_table_pointer current_value{}; + asm("sgdt %[output]" : [output] "=m"(current_value)); + return current_value; + } + + auto load_global_descriptor_table( + context_switching::segment_descriptor_table::global_descriptor_table_pointer const & gdt_pointer) -> void + { + asm volatile("lgdt %[input]" : /* no output from call */ : [input] "m"(gdt_pointer)); + } +} // namespace teachos::arch::kernel::cpu diff --git a/arch/x86_64/pre/src/kernel/cpu/idtr.cpp b/arch/x86_64/pre/src/kernel/cpu/idtr.cpp new file mode 100644 index 0000000..7aa20c1 --- /dev/null +++ b/arch/x86_64/pre/src/kernel/cpu/idtr.cpp @@ -0,0 +1,18 @@ +#include "arch/kernel/cpu/idtr.hpp" + +namespace teachos::arch::kernel::cpu +{ + auto store_interrupt_descriptor_table() + -> context_switching::interrupt_descriptor_table::interrupt_descriptor_table_pointer + { + context_switching::interrupt_descriptor_table::interrupt_descriptor_table_pointer current_value{}; + asm("sidt %[output]" : [output] "=m"(current_value)); + return current_value; + } + + auto load_interrupt_descriptor_table( + context_switching::interrupt_descriptor_table::interrupt_descriptor_table_pointer const & idt_pointer) -> void + { + asm volatile("lidt %[input]" : /* no output from call */ : [input] "m"(idt_pointer)); + } +} // namespace teachos::arch::kernel::cpu diff --git a/arch/x86_64/pre/src/kernel/cpu/if.cpp b/arch/x86_64/pre/src/kernel/cpu/if.cpp new file mode 100644 index 0000000..5d056fc --- /dev/null +++ b/arch/x86_64/pre/src/kernel/cpu/if.cpp @@ -0,0 +1,13 @@ +namespace teachos::arch::kernel::cpu +{ + auto set_interrupt_flag() -> void + { + asm volatile("sti"); + } + + auto clear_interrupt_flag() -> void + { + asm volatile("cli"); + } + +} // namespace teachos::arch::kernel::cpu diff --git a/arch/x86_64/pre/src/kernel/cpu/msr.cpp b/arch/x86_64/pre/src/kernel/cpu/msr.cpp new file mode 100644 index 0000000..9d6a318 --- /dev/null +++ b/arch/x86_64/pre/src/kernel/cpu/msr.cpp @@ -0,0 +1,31 @@ +#include "arch/kernel/cpu/msr.hpp" + +namespace teachos::arch::kernel::cpu +{ + namespace + { + constexpr auto IA32_EFER_ADDRESS = 0xC000'0080; + } + + auto read_msr(uint32_t msr) -> uint64_t + { + uint32_t low, high; + asm volatile("rdmsr" : "=a"(low), "=d"(high) : "c"(msr)); + return (static_cast<uint64_t>(high) << 32) | low; + } + + auto write_msr(uint32_t msr, uint64_t value) -> void + { + uint32_t low = value; + uint32_t high = value >> 32; + asm volatile("wrmsr" + : /* no output from call */ + : "c"(msr), "a"(low), "d"(high)); + } + + auto set_efer_bit(efer_flags flag) -> void + { + auto const efer = read_msr(IA32_EFER_ADDRESS); + write_msr(IA32_EFER_ADDRESS, static_cast<std::underlying_type<efer_flags>::type>(flag) | efer); + } +} // namespace teachos::arch::kernel::cpu diff --git a/arch/x86_64/pre/src/kernel/cpu/segment_register.cpp b/arch/x86_64/pre/src/kernel/cpu/segment_register.cpp new file mode 100644 index 0000000..b08c9c4 --- /dev/null +++ b/arch/x86_64/pre/src/kernel/cpu/segment_register.cpp @@ -0,0 +1,98 @@ +#include "arch/kernel/cpu/segment_register.hpp" + +#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp" +#include "arch/exception_handling/assert.hpp" + +namespace teachos::arch::kernel::cpu +{ + auto reload_data_segment_registers() -> void + { + asm volatile("xor %%rax, %%rax\n" + "mov %%rax, %%ss\n" + "mov %%rax, %%ds\n" + "mov %%rax, %%es\n" + "mov %%rax, %%fs\n" + "mov %%rax, %%gs\n" + : /* no output from call */ + : /* no input to call */ + : "rax"); + } + + auto set_data_segment_registers(context_switching::interrupt_descriptor_table::segment_selector data_segment) -> void + { + asm volatile("xor %%rax, %%rax\n" + "mov %[input], %%ax\n" + "mov %%rax, %%ds\n" + "mov %%rax, %%es\n" + "mov %%rax, %%fs\n" + "mov %%rax, %%gs\n" + : /* no output from call */ + : [input] "m"(data_segment) + : "rax"); + } + + auto read_code_segment_register() -> context_switching::interrupt_descriptor_table::segment_selector + { + context_switching::interrupt_descriptor_table::segment_selector current_value{}; + asm volatile("mov %%cs, %[output]" : [output] "=r"(current_value)); + return current_value; + } + + auto validate_data_segment_registers(context_switching::interrupt_descriptor_table::segment_selector data_segment) + -> void + { + context_switching::interrupt_descriptor_table::segment_selector ss{}; + context_switching::interrupt_descriptor_table::segment_selector ds{}; + context_switching::interrupt_descriptor_table::segment_selector es{}; + context_switching::interrupt_descriptor_table::segment_selector fs{}; + context_switching::interrupt_descriptor_table::segment_selector gs{}; + + asm volatile( + "mov %%ss, %[ss_output]\n" + "mov %%ds, %[ds_output]\n" + "mov %%es, %[es_output]\n" + "mov %%fs, %[fs_output]\n" + "mov %%gs, %[gs_output]\n" + : [ss_output] "=r"(ss), [ds_output] "=r"(ds), [es_output] "=r"(es), [fs_output] "=r"(fs), [gs_output] "=r"(gs)); + + auto result = (ss == ds && ss == es && ss == fs && ss == gs); + exception_handling::assert(result, "[Segment Register] Values in data register are not the same."); + result = (ss == data_segment); + exception_handling::assert( + result, "[Segment Register] Expected Data Segment is not the same as the value in the Stack Segment register."); + } + + auto validate_code_segment_register(context_switching::interrupt_descriptor_table::segment_selector code_segment) + -> void + { + auto const cs = read_code_segment_register(); + exception_handling::assert( + cs == code_segment, + "[Segment Register] Expected Code Segment is not the same as the value in the Code Segment register."); + } + + auto validate_segment_registers(context_switching::interrupt_descriptor_table::segment_selector data_segment, + context_switching::interrupt_descriptor_table::segment_selector code_segment) -> void + { + validate_data_segment_registers(data_segment); + validate_code_segment_register(code_segment); + } + + auto set_code_segment_register(context_switching::interrupt_descriptor_table::segment_selector data_segment, + context_switching::interrupt_descriptor_table::segment_selector code_segment, + uint64_t address) -> void + { + asm volatile("mov %%rsp, %%rax\n" + "push %[data_segment]\n" + "push %%rax\n" + "pushfq\n" + "push %[code_segment]\n" + "mov %[return_function], %%rax\n" + "push %%rax\n" + "iretq\n" + : /* no output from call */ + : [data_segment] "m"(data_segment), [code_segment] "m"(code_segment), [return_function] "r"(address) + : "rax"); + } + +} // namespace teachos::arch::kernel::cpu diff --git a/arch/x86_64/pre/src/kernel/cpu/tr.cpp b/arch/x86_64/pre/src/kernel/cpu/tr.cpp new file mode 100644 index 0000000..a435540 --- /dev/null +++ b/arch/x86_64/pre/src/kernel/cpu/tr.cpp @@ -0,0 +1,16 @@ +#include "arch/kernel/cpu/tr.hpp" + +namespace teachos::arch::kernel::cpu +{ + auto store_task_register() -> uint16_t + { + uint16_t current_value{}; + asm("str %[output]" : [output] "=r"(current_value)); + return current_value; + } + + auto load_task_register(uint16_t gdt_offset) -> void + { + asm volatile("ltr %[input]" : /* no output from call */ : [input] "m"(gdt_offset)); + } +} // namespace teachos::arch::kernel::cpu diff --git a/arch/x86_64/pre/src/kernel/main.cpp b/arch/x86_64/pre/src/kernel/main.cpp new file mode 100644 index 0000000..43b5f90 --- /dev/null +++ b/arch/x86_64/pre/src/kernel/main.cpp @@ -0,0 +1,71 @@ +#include "arch/kernel/main.hpp" + +#include "arch/boot/pointers.hpp" +#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp" +#include "arch/context_switching/main.hpp" +#include "arch/kernel/cpu/if.hpp" +#include "arch/kernel/cpu/segment_register.hpp" +#include "arch/memory/heap/bump_allocator.hpp" +#include "arch/memory/heap/global_heap_allocator.hpp" +#include "arch/memory/main.hpp" +#include "arch/memory/multiboot/reader.hpp" +#include "arch/stl/vector.hpp" +#include "arch/video/vga/text.hpp" + +namespace teachos::arch::kernel +{ + auto stack_overflow_test(int count) -> int + { + int test[5000] = {}; + if (test[0] == 0xFFFF) + { + return count; + } + count = stack_overflow_test(count); + return count++; + } + + auto heap_test() -> void + { + auto test2 = new memory::multiboot::memory_information{}; + auto test3 = new memory::multiboot::memory_information{}; + auto test4 = *test2; + auto test5 = *test3; + test4.kernel_end = 5000; + test5.kernel_end = 3000; + auto test6 = test4.kernel_end; + auto test7 = test5.kernel_end; + auto test8 = memory::multiboot::read_multiboot2(); + if (test6 && test7 && test8.kernel_end) + { + video::vga::text::write("Heap test successful", video::vga::text::common_attributes::green_on_black); + } + test2->kernel_end = 2000; + test2->kernel_start = 1000; + test2->multiboot_start = 2000; + delete test2; + delete test3; + + auto test9 = new int(50); + delete test9; + } + + auto main() -> void + { + video::vga::text::clear(); + video::vga::text::cursor(false); + video::vga::text::write("TeachOS is starting up...", video::vga::text::common_attributes::green_on_black); + video::vga::text::newline(); + + memory::initialize_memory_management(); + // stack_overflow_test(0); + + memory::heap::global_heap_allocator::register_heap_allocator(memory::heap::heap_allocator_type::LINKED_LIST); + // heap_test(); + + auto address = memory::heap::global_heap_allocator::kmalloc(8U); + (void)address; + + context_switching::switch_to_user_mode(); + } +} // namespace teachos::arch::kernel diff --git a/arch/x86_64/pre/src/memory/heap/bump_allocator.cpp b/arch/x86_64/pre/src/memory/heap/bump_allocator.cpp new file mode 100644 index 0000000..525f45c --- /dev/null +++ b/arch/x86_64/pre/src/memory/heap/bump_allocator.cpp @@ -0,0 +1,54 @@ +#include "arch/memory/heap/bump_allocator.hpp" + +#include "arch/exception_handling/assert.hpp" + +#include <limits> +#include <type_traits> + +namespace teachos::arch::memory::heap +{ + namespace + { + template<typename T> + auto saturating_add(T x, T y) -> T + requires std::is_unsigned_v<T> + { + if (x > std::numeric_limits<T>::max() - y) + { + return std::numeric_limits<T>::max(); + } + T result = x + y; + return result; + } + } // namespace + + auto bump_allocator::allocate(std::size_t size) -> void * + { + // Reading the value only has to be done once, because compare_exchange_weak updates the value as well if the + // exchange failed, becuase the value was not the expected one. + auto alloc_start = next.load(std::memory_order::relaxed); + // Repeat allocation until it succeeds, has to be done, because another allocator could overtake it at any time + // causing the value to differ and the calculation to have to be redone. + for (;;) + { + auto const alloc_end = saturating_add(alloc_start, size); + arch::exception_handling::assert(alloc_end <= heap_end, "[Heap Allocator] Out of memory"); + // Check if the atomic value is still the one initally loaded, if it isn't we have been overtaken by another + // thread and need to redo the calculation. Spurious failure by weak can be ignored, because the whole allocation + // is wrapped in an infinite for loop so a failure that wasn't actually one will simply be retried until it works. + auto const updated = next.compare_exchange_weak(alloc_start, alloc_end, std::memory_order::relaxed); + if (updated) + { + return reinterpret_cast<void *>(alloc_start); + } + } + } + + auto bump_allocator::deallocate(void * pointer) noexcept -> void + { + if (pointer) + { + } + } + +} // namespace teachos::arch::memory::heap diff --git a/arch/x86_64/pre/src/memory/heap/global_heap_allocator.cpp b/arch/x86_64/pre/src/memory/heap/global_heap_allocator.cpp new file mode 100644 index 0000000..709cda1 --- /dev/null +++ b/arch/x86_64/pre/src/memory/heap/global_heap_allocator.cpp @@ -0,0 +1,148 @@ +#include "arch/memory/heap/global_heap_allocator.hpp" + +#include "arch/context_switching/syscall/main.hpp" +#include "arch/exception_handling/assert.hpp" +#include "arch/kernel/cpu/segment_register.hpp" +#include "arch/memory/heap/bump_allocator.hpp" +#include "arch/memory/heap/linked_list_allocator.hpp" +#include "arch/memory/heap/user_heap_allocator.hpp" + +namespace teachos::arch::memory::heap +{ + namespace + { + constexpr char NOT_REGISTRED_ERROR_MESSAGE[] = + "Attempted to allocate or deallocate using the global_heap_allocator before " + "register_heap_allocation_type was called."; + constexpr uint16_t KERNEL_CODE_INDEX = 1U; + + [[gnu::section(".user_text")]] + auto os_in_kernel_mode() -> bool + { + auto const cs = teachos::arch::kernel::cpu::read_code_segment_register(); + return cs.get_index() == KERNEL_CODE_INDEX; + } + } // namespace + + heap_allocator * global_heap_allocator::kernel_allocator_instance = nullptr; + user_heap_allocator * global_heap_allocator::user_allocator_instance = nullptr; + + auto global_heap_allocator::kmalloc(std::size_t size) -> void * + { + return kernel().allocate(size); + } + + auto global_heap_allocator::kfree(void * pointer) noexcept -> void + { + kernel().deallocate(pointer); + } + + auto global_heap_allocator::malloc(std::size_t size) -> void * + { + return user().allocate(size); + } + + auto global_heap_allocator::free(void * pointer) noexcept -> void + { + user().deallocate(pointer); + } + + auto global_heap_allocator::register_heap_allocator(heap_allocator_type new_type) -> void + { + exception_handling::assert(kernel_allocator_instance == nullptr, + "Calling register_heap_allocator_type can only be done once."); + + switch (new_type) + { + case heap_allocator_type::NONE: + // Nothing to do + break; + case heap_allocator_type::BUMP: + { + bump_allocator static kernel_allocator{KERNEL_HEAP_START, KERNEL_HEAP_START + KERNEL_HEAP_SIZE}; + kernel_allocator_instance = &kernel_allocator; + break; + } + case heap_allocator_type::LINKED_LIST: + { + linked_list_allocator static kernel_allocator{KERNEL_HEAP_START, KERNEL_HEAP_START + KERNEL_HEAP_SIZE}; + kernel_allocator_instance = &kernel_allocator; + break; + } + } + + [[gnu::section(".user_data")]] user_heap_allocator static user_allocator{}; + user_allocator_instance = &user_allocator; + } + + auto global_heap_allocator::kernel() -> heap_allocator & + { + exception_handling::assert(kernel_allocator_instance != nullptr, NOT_REGISTRED_ERROR_MESSAGE); + + return *kernel_allocator_instance; + } + + auto global_heap_allocator::user() -> user_heap_allocator & + { + context_switching::syscall::syscall( + context_switching::syscall::type::ASSERT, + {user_allocator_instance != nullptr, reinterpret_cast<uint64_t>(&NOT_REGISTRED_ERROR_MESSAGE)}); + return *user_allocator_instance; + } +} // namespace teachos::arch::memory::heap + +auto operator new(std::size_t size) -> void * +{ + if (teachos::arch::memory::heap::os_in_kernel_mode()) + { + return teachos::arch::memory::heap::global_heap_allocator::kmalloc(size); + } + return teachos::arch::memory::heap::global_heap_allocator::malloc(size); +} + +auto operator delete(void * pointer) noexcept -> void +{ + if (teachos::arch::memory::heap::os_in_kernel_mode()) + { + teachos::arch::memory::heap::global_heap_allocator::kfree(pointer); + } + teachos::arch::memory::heap::global_heap_allocator::free(pointer); +} + +auto operator delete(void * pointer, std::size_t size) noexcept -> void +{ + (void)size; + if (teachos::arch::memory::heap::os_in_kernel_mode()) + { + teachos::arch::memory::heap::global_heap_allocator::kfree(pointer); + } + teachos::arch::memory::heap::global_heap_allocator::free(pointer); +} + +auto operator new[](std::size_t size) -> void * +{ + if (teachos::arch::memory::heap::os_in_kernel_mode()) + { + return teachos::arch::memory::heap::global_heap_allocator::kmalloc(size); + } + return teachos::arch::memory::heap::global_heap_allocator::malloc(size); +} + +auto operator delete[](void * pointer) noexcept -> void +{ + if (teachos::arch::memory::heap::os_in_kernel_mode()) + { + teachos::arch::memory::heap::global_heap_allocator::kfree(pointer); + } + teachos::arch::memory::heap::global_heap_allocator::free(pointer); +} + +auto operator delete[](void * pointer, std::size_t size) noexcept -> void +{ + (void)size; + if (teachos::arch::memory::heap::os_in_kernel_mode()) + { + teachos::arch::memory::heap::global_heap_allocator::kfree(pointer); + } + teachos::arch::memory::heap::global_heap_allocator::free(pointer); +} diff --git a/arch/x86_64/pre/src/memory/heap/linked_list_allocator.cpp b/arch/x86_64/pre/src/memory/heap/linked_list_allocator.cpp new file mode 100644 index 0000000..00ca366 --- /dev/null +++ b/arch/x86_64/pre/src/memory/heap/linked_list_allocator.cpp @@ -0,0 +1,177 @@ +#include "arch/memory/heap/linked_list_allocator.hpp" + +#include "arch/exception_handling/assert.hpp" +#include "arch/exception_handling/panic.hpp" + +#include <algorithm> + +namespace teachos::arch::memory::heap +{ + linked_list_allocator::linked_list_allocator(std::size_t heap_start, std::size_t heap_end) + : first(nullptr) + , mutex{kstd::mutex{}} + { + auto const heap_size = heap_end - heap_start; + exception_handling::assert( + heap_size > min_allocatable_size(), + "[Linked List Allocator] Total heap size can not be smaller than minimum of 16 bytes to hold " + "atleast one memory hole entry"); + first = new (reinterpret_cast<void *>(heap_start)) memory_block(heap_size, nullptr); + } + + auto linked_list_allocator::allocate(std::size_t size) -> void * + { + // Add size of size_t to the total allocated size, because we add a header that includes the size of the allocated + // block, to allow for deallocation without the need to call with the corresponding size + auto const total_size = size + sizeof(std::size_t); + mutex.lock(); + + memory_block * previous = nullptr; + auto current = first; + + while (current != nullptr) + { + if (current->size == total_size) + { + auto const memory_address = remove_free_memory_block(previous, current); + new (memory_address) std::size_t(total_size); + mutex.unlock(); + return reinterpret_cast<void *>(reinterpret_cast<std::size_t>(memory_address) + sizeof(std::size_t)); + } + else if (current->size >= total_size + min_allocatable_size()) + { + // Ensure that the allocated size block is atleast 16 bytes (required because if we free the hole afterwards + // there needs to be enough space for a memory block). Therefore we allocate more than is actually required if + // the total size was less and simply deallocate it as well + auto const max_size = std::max(total_size, min_allocatable_size()); + auto const memory_address = split_free_memory_block(previous, current, max_size); + new (memory_address) std::size_t(max_size); + mutex.unlock(); + return reinterpret_cast<void *>(reinterpret_cast<std::size_t>(memory_address) + sizeof(std::size_t)); + } + + previous = current; + current = current->next; + } + + exception_handling::panic("[Linked List Allocator] Out of memory"); + } + + auto linked_list_allocator::deallocate(void * pointer) noexcept -> void + { + mutex.lock(); + + // Read configured header size of the complete allocated block + auto const header_pointer = reinterpret_cast<void *>(reinterpret_cast<std::size_t>(pointer) - sizeof(std::size_t)); + auto const total_size = *reinterpret_cast<std::size_t *>(header_pointer); + + auto const start_address = reinterpret_cast<std::size_t>(header_pointer); + auto const end_address = start_address + total_size; + + memory_block * previous = nullptr; + auto current = first; + + while (current != nullptr) + { + // Current address of the free memory block now points to an address that is after our block to deallocate in heap + // memory space. + if (reinterpret_cast<std::size_t>(current) >= end_address) + { + break; + } + + previous = current; + current = current->next; + } + + coalesce_free_memory_block(previous, current, header_pointer, total_size); + mutex.unlock(); + } + + auto linked_list_allocator::remove_free_memory_block(memory_block * previous_block, memory_block * current_block) + -> void * + { + return replace_free_memory_block(previous_block, current_block, current_block->next); + } + + auto linked_list_allocator::split_free_memory_block(memory_block * previous_block, memory_block * current_block, + std::size_t size) -> void * + { + auto const end_address = reinterpret_cast<std::size_t>(current_block) + size; + auto const new_block = + new (reinterpret_cast<void *>(end_address)) memory_block(current_block->size - size, current_block->next); + return replace_free_memory_block(previous_block, current_block, new_block); + } + + auto linked_list_allocator::replace_free_memory_block(memory_block * previous_block, memory_block * current_block, + memory_block * new_block) -> void * + { + auto const start_address = reinterpret_cast<std::size_t>(current_block); + // If we want to allocate into the first block that is before any other free block, then there exists no previous + // free block (nullptr). Therefore we have to overwrite the first block instead of overwriting its next value. + if (previous_block == nullptr) + { + first = new_block; + } + else + { + previous_block->next = new_block; + } + current_block->~memory_block(); + return reinterpret_cast<void *>(start_address); + } + + auto linked_list_allocator::coalesce_free_memory_block(memory_block * previous_block, memory_block * current_block, + void * pointer, std::size_t size) -> void + { + auto const start_address = reinterpret_cast<std::size_t>(pointer); + auto const end_address = start_address + size; + + // Inital values if there are no adjacent blocks either before or after, meaning we have to simply create a free + // memory block that is placed in between the previous and next block. + auto block_size = size; + auto next_block = current_block; + + // If the block we want to deallocate is before another free block and we can therefore combine both into one. + // This is done by deleting the current free block and creating a new block at the start address of the block to + // deallocate with both the size of the block to deallcoate and the free block next to it. + if (end_address == reinterpret_cast<std::size_t>(current_block)) + { + block_size += current_block->size; + next_block = current_block->next; + current_block->~memory_block(); + } + + // If the block we want to deallocate is behind another free block and we can therefore combine both into one. + // This is done by simply changin the size of the previous block to include the size of the block to deallocate. + // This is done, because the previous block might still be referencered by the next field of other memory blocks. + if (previous_block != nullptr && + start_address == (reinterpret_cast<std::size_t>(previous_block) + previous_block->size)) + { + block_size += previous_block->size; + + previous_block->size = block_size; + previous_block->next = next_block; + return; + } + + // Check if the block we want to deallocate is contained in the previous block, because if it is it can only mean + // that the block has already been deallocated and we therefore attempted a double free. + exception_handling::assert(previous_block == nullptr || + start_address >= + (reinterpret_cast<std::size_t>(previous_block) + previous_block->size), + "[Linked List Allocator] Attempted double free detected"); + + auto const new_block = new (pointer) memory_block(block_size, next_block); + // If we want to deallocate the first block that is before any other free block, then there exists no previous free + // block (nullptr). Therefore we have to overwrite the first block instead of overwriting its + // next value. + if (previous_block == nullptr) + { + first = new_block; + return; + } + previous_block->next = new_block; + } + +} // namespace teachos::arch::memory::heap diff --git a/arch/x86_64/pre/src/memory/heap/memory_block.cpp b/arch/x86_64/pre/src/memory/heap/memory_block.cpp new file mode 100644 index 0000000..4c07454 --- /dev/null +++ b/arch/x86_64/pre/src/memory/heap/memory_block.cpp @@ -0,0 +1,18 @@ +#include "arch/memory/heap/memory_block.hpp" + +#include <string.h> + +namespace teachos::arch::memory::heap +{ + memory_block::memory_block(std::size_t size, memory_block * next) + { + memset(static_cast<void *>(this), 0U, size); + this->size = size; + this->next = next; + } + + memory_block::~memory_block() + { + memset(static_cast<void *>(this), 0U, sizeof(memory_block)); + } +} // namespace teachos::arch::memory::heap diff --git a/arch/x86_64/pre/src/memory/heap/user_heap_allocator.cpp b/arch/x86_64/pre/src/memory/heap/user_heap_allocator.cpp new file mode 100644 index 0000000..96de005 --- /dev/null +++ b/arch/x86_64/pre/src/memory/heap/user_heap_allocator.cpp @@ -0,0 +1,200 @@ +#include "arch/memory/heap/user_heap_allocator.hpp" + +#include "arch/context_switching/syscall/main.hpp" + +#include <algorithm> + +namespace teachos::arch::memory::heap +{ + auto user_heap_allocator::allocate(std::size_t size) -> void * + { + // Add size of size_t to the total allocated size, because we add a header that includes the size of the allocated + // block, to allow for deallocation without the need to call with the corresponding size + auto const total_size = size + sizeof(std::size_t); + mutex.lock(); + + memory_block * previous = nullptr; + auto current = first; + + while (current != nullptr) + { + auto memory = allocate_into_memory_block_if_big_enough(current, previous, total_size); + if (memory.has_value()) + { + return memory.value(); + } + + previous = current; + current = current->next; + } + + current = expand_heap_if_full(); + + if (current != nullptr) + { + auto memory = allocate_into_memory_block_if_big_enough(current, previous, total_size); + if (memory.has_value()) + { + return memory.value(); + } + } + + constexpr char OUT_OF_MEMORY_ERROR_MESSAGE[] = "[Linked List Allocator] Out of memory"; + context_switching::syscall::syscall(context_switching::syscall::type::ASSERT, + {false, reinterpret_cast<uint64_t>(&OUT_OF_MEMORY_ERROR_MESSAGE)}); + return nullptr; + } + + auto user_heap_allocator::deallocate(void * pointer) noexcept -> void + { + mutex.lock(); + + // Read configured header size of the complete allocated block + auto const header_pointer = reinterpret_cast<void *>(reinterpret_cast<std::size_t>(pointer) - sizeof(std::size_t)); + auto const total_size = *reinterpret_cast<std::size_t *>(header_pointer); + + auto const start_address = reinterpret_cast<std::size_t>(header_pointer); + auto const end_address = start_address + total_size; + + memory_block * previous = nullptr; + auto current = first; + + while (current != nullptr) + { + // Current address of the free memory block now points to an address that is after our block to deallocate in heap + // memory space. + if (reinterpret_cast<std::size_t>(current) >= end_address) + { + break; + } + + previous = current; + current = current->next; + } + + coalesce_free_memory_block(previous, current, header_pointer, total_size); + mutex.unlock(); + } + + auto user_heap_allocator::allocate_into_memory_block_if_big_enough(memory_block * current, memory_block * previous, + std::size_t total_size) -> std::optional<void *> + { + if (current->size == total_size) + { + auto const memory_address = remove_free_memory_block(previous, current); + new (memory_address) std::size_t(total_size); + mutex.unlock(); + return reinterpret_cast<void *>(reinterpret_cast<std::size_t>(memory_address) + sizeof(std::size_t)); + } + else if (current->size >= total_size + min_allocatable_size()) + { + // Ensure that the allocated size block is atleast 16 bytes (required because if we free the hole afterwards + // there needs to be enough space for a memory block). Therefore we allocate more than is actually required if + // the total size was less and simply deallocate it as well + auto const max_size = std::max(total_size, min_allocatable_size()); + auto const memory_address = split_free_memory_block(previous, current, max_size); + new (memory_address) std::size_t(max_size); + mutex.unlock(); + return reinterpret_cast<void *>(reinterpret_cast<std::size_t>(memory_address) + sizeof(std::size_t)); + } + return std::nullopt; + } + + auto user_heap_allocator::expand_heap_if_full() -> memory_block * + { + auto const result = context_switching::syscall::syscall(context_switching::syscall::type::EXPAND_HEAP); + + uint64_t const heap_start = result.values.arg_0; + uint64_t const heap_size = result.values.arg_1; + return !result.error_code ? new (reinterpret_cast<void *>(heap_start)) memory_block(heap_size, nullptr) : nullptr; + } + + auto user_heap_allocator::remove_free_memory_block(memory_block * previous_block, memory_block * current_block) + -> void * + { + return replace_free_memory_block(previous_block, current_block, current_block->next); + } + + auto user_heap_allocator::split_free_memory_block(memory_block * previous_block, memory_block * current_block, + std::size_t size) -> void * + { + auto const end_address = reinterpret_cast<std::size_t>(current_block) + size; + auto const new_block = + new (reinterpret_cast<void *>(end_address)) memory_block(current_block->size - size, current_block->next); + return replace_free_memory_block(previous_block, current_block, new_block); + } + + auto user_heap_allocator::replace_free_memory_block(memory_block * previous_block, memory_block * current_block, + memory_block * new_block) -> void * + { + auto const start_address = reinterpret_cast<std::size_t>(current_block); + // If we want to allocate into the first block that is before any other free block, then there exists no previous + // free block (nullptr). Therefore we have to overwrite the first block instead of overwriting its next value. + if (previous_block == nullptr) + { + first = new_block; + } + else + { + previous_block->next = new_block; + } + current_block->~memory_block(); + return reinterpret_cast<void *>(start_address); + } + + auto user_heap_allocator::coalesce_free_memory_block(memory_block * previous_block, memory_block * current_block, + void * pointer, std::size_t size) -> void + { + auto const start_address = reinterpret_cast<std::size_t>(pointer); + auto const end_address = start_address + size; + + // Inital values if there are no adjacent blocks either before or after, meaning we have to simply create a free + // memory block that is placed in between the previous and next block. + auto block_size = size; + auto next_block = current_block; + + // If the block we want to deallocate is before another free block and we can therefore combine both into one. + // This is done by deleting the current free block and creating a new block at the start address of the block to + // deallocate with both the size of the block to deallcoate and the free block next to it. + if (end_address == reinterpret_cast<std::size_t>(current_block)) + { + block_size += current_block->size; + next_block = current_block->next; + current_block->~memory_block(); + } + + // If the block we want to deallocate is behind another free block and we can therefore combine both into one. + // This is done by simply changin the size of the previous block to include the size of the block to deallocate. + // This is done, because the previous block might still be referencered by the next field of other memory blocks. + if (previous_block != nullptr && + start_address == (reinterpret_cast<std::size_t>(previous_block) + previous_block->size)) + { + block_size += previous_block->size; + + previous_block->size = block_size; + previous_block->next = next_block; + return; + } + + // Check if the block we want to deallocate is contained in the previous block, because if it is it can only mean + // that the block has already been deallocated and we therefore attempted a double free. + constexpr char DOUBLE_FREE_ERROR_MESSAGE[] = "[Linked List Allocator] Attempted double free detected"; + context_switching::syscall::syscall( + context_switching::syscall::type::ASSERT, + {previous_block == nullptr || + start_address >= (reinterpret_cast<std::size_t>(previous_block) + previous_block->size), + reinterpret_cast<uint64_t>(&DOUBLE_FREE_ERROR_MESSAGE)}); + + auto const new_block = new (pointer) memory_block(block_size, next_block); + // If we want to deallocate the first block that is before any other free block, then there exists no previous free + // block (nullptr). Therefore we have to overwrite the first block instead of overwriting its + // next value. + if (previous_block == nullptr) + { + first = new_block; + return; + } + previous_block->next = new_block; + } + +} // namespace teachos::arch::memory::heap diff --git a/arch/x86_64/pre/src/user/main.cpp b/arch/x86_64/pre/src/user/main.cpp new file mode 100644 index 0000000..8b07e4a --- /dev/null +++ b/arch/x86_64/pre/src/user/main.cpp @@ -0,0 +1,35 @@ +#include "arch/user/main.hpp" + +#include "arch/context_switching/syscall/main.hpp" +#include "arch/memory/heap/global_heap_allocator.hpp" + +#include <algorithm> +#include <array> +#include <atomic> +#include <ranges> + +namespace teachos::arch::user +{ + auto main() -> void + { + constexpr char syscall_message[] = "Successfully entered user mode and wrote to VGA buffer via syscall!"; + context_switching::syscall::syscall(context_switching::syscall::type::WRITE, + {reinterpret_cast<uint64_t>(&syscall_message)}); + + // Test C++ standard library + std::array<std::atomic<uint8_t>, 4> array_test = {std::atomic<uint8_t>{5}, std::atomic<uint8_t>{10}, + std::atomic<uint8_t>{15}, std::atomic<uint8_t>{20}}; + std::ranges::for_each(array_test, [](auto & item) { + auto value = item.load(); + uint8_t max_value = std::max(value, uint8_t{10}); + item.exchange(max_value + 2); + }); + + auto address = new uint64_t{10U}; + (void)address; + + for (;;) + { + } + } +} // namespace teachos::arch::user |