diff options
Diffstat (limited to 'arch/x86_64/src/boot')
| -rw-r--r-- | arch/x86_64/src/boot/boot.s | 368 | ||||
| -rw-r--r-- | arch/x86_64/src/boot/boot32.S | 449 | ||||
| -rw-r--r-- | arch/x86_64/src/boot/crti.s | 13 | ||||
| -rw-r--r-- | arch/x86_64/src/boot/crtn.s | 9 | ||||
| -rw-r--r-- | arch/x86_64/src/boot/entry64.s | 60 | ||||
| -rw-r--r-- | arch/x86_64/src/boot/initialize_runtime.cpp | 26 |
6 files changed, 535 insertions, 390 deletions
diff --git a/arch/x86_64/src/boot/boot.s b/arch/x86_64/src/boot/boot.s deleted file mode 100644 index 7932045..0000000 --- a/arch/x86_64/src/boot/boot.s +++ /dev/null @@ -1,368 +0,0 @@ -.extern _end_physical -.extern _init -.extern kernel_main - - -/** - * Uninitialized data for the bootstrapping process. - */ -.section .boot_bss, "aw", @nobits - -/** - * Reserve some space for the Multiboot 2 information pointer. - */ -.global multiboot_information_pointer -multiboot_information_pointer: .skip 4 - -/** - * Align page maps to 4 KiB or the assembler code, will cause crashes when attempting to enable paging. - */ -.align 4096 - -/** - * Reserve space for the page maps we are going to use during startup. - * - * Note: We are going to use large pages to make the initial mapping code - * simpler. - * - * We need: - * - A single PML 4 (since we will only use 4-level paging) - * - 1 PML 3 - * - 1 PML 2 - */ - -.global page_map_level_4 -page_map_level_4: .skip 512 * 8 - -.global page_map_level_3 -page_map_level_3: .skip 512 * 8 - -.global page_map_level_2 -page_map_level_2: .skip 512 * 8 - -/** - * Stack space for the bootstrapping process. - * - * Note: We are going to reserve 1 MiB for now. If/when the kernel requires - * more space to run, it will have to relocate the stack. - */ -.section .boot_stack, "aw", @nobits -.align 16 - -stack_bottom: .skip 1 << 20 -stack_top: - -/** - * Constants for the bootstrapping process. - */ -.section .boot_rodata, "a", @progbits - -/** - * A valid Global Descriptor Table is still required in long mode. However, we - * only need a single entry for the "code segment", so we will setup a single - * segment table below. - * - * Bit 43: "E" in the access byte => mark the segment as executable. - * Bit 44: "S" in the access byte => mark the segment as code or data. - * Bit 47: "P" in the access byte => mark the segment as being present. - * Bit 53: "L" in the flags byte => mark the segment as being for long mode - */ - -global_descriptor_table: .quad 0 -global_descriptor_table_code = . - global_descriptor_table -.quad (1<<43) | (1<<44) | (1<<47) | (1<<53) - -/** - * We also need a pointer that we can load into the GDTR. - * - * The pointer consists of a word describing the size of the table minus 1 and - * the pointer to the actual table. - */ -global_descriptor_table_pointer: -.word . - global_descriptor_table - 1 -.quad global_descriptor_table - -/** - * We are going to print some messages in case we panic during boot, so we are - * going to store them here as well - */ -.global message_prefix_panic -message_prefix_panic: -.string "TeachOS Panic: " -message_not_loaded_by_multiboot2: -.string "The operating system was not loaded by a Multiboot 2 loader." -message_cpuid_instruction_no_supported: -.string "The 'cpuid' instruction is not supported on this platform." -mesage_long_mode_not_supported: -.string "Long mode is not supported by this platform." - -/** - * Mutable data for the bootstrapping process. - */ -.section .boot_data, "aw", @progbits - -/** - * We need a pointer to our current position in the VGA text buffer. - */ -.global vga_buffer_pointer -vga_buffer_pointer: .long 0xb8000 - -/** - * Code for the bootstrapping process. - */ -.section .boot_text, "ax", @progbits -.align 16 -.code32 - -.global halt -halt: -1: - hlt - jmp 1b - -/** - * Print a given panic message and then halt the machine. - * - * Parameters: - * - [stack - 0] message: the message to print - */ -_panic: - push %ebp - mov %esp, %ebp - - push message_prefix_panic - push $0x4f - call _print - add $8, %esp - - push 8(%ebp) - push 0x4f - call _print - add $8, %esp - - call halt - -/** - * Print a message via the VGA buffer. - * - * Parameters: - * - [stack - 4] message: the message to print - * - [stack - 0] color: the color of the message - */ -_print: - push %ebp - mov %esp, %ebp - - push %ebx - push %esi - mov 8(%ebp), %eax - mov 12(%ebp), %ebx - mov $0, %ecx - mov (vga_buffer_pointer), %esi - -.Lprint_loop: - mov (%ebx, %ecx), %dl - test %dl, %dl - je .Lupdate_vga_buffer_address - mov %dl, (%esi, %ecx, 2) - mov %al, 1(%esi, %ecx, 2) - inc %ecx - jmp .Lprint_loop - -.Lupdate_vga_buffer_address: - shl $1, %ecx - add %ecx, (vga_buffer_pointer) - -.Lprint_end: - pop %esi - pop %ebx - mov %ebp, %esp - pop %ebp - ret - -/** - * This is our entry point after being loaded by the bootloader. - * - * Having this in assembly makes it easier for us to keep things together. - */ -.global _start -_start: - mov $stack_top, %esp - mov %esp, %ebp - - call assert_loaded_by_multiboot2_loader - call assert_cpuid_instruction_is_supported - call assert_cpu_supports_long_mode - call prepare_page_maps - call enable_paging - call enable_sse - - lgdt (global_descriptor_table_pointer) - jmp $global_descriptor_table_code, $_transition_to_long_mode - - call halt - -/** - * Assert that the CPU supports going into long mode. - */ -assert_cpu_supports_long_mode: - mov $0x80000000, %eax - cpuid - cmp $0x80000001, %eax - jb .Llong_mode_assertion_failed - - mov $0x80000001, %eax - cpuid - test $(1 << 29), %edx - jz .Llong_mode_assertion_failed - ret -.Llong_mode_assertion_failed: - push $mesage_long_mode_not_supported - call _panic - -/** - * Assert that the CPU supports the CPUID instruction. - * - * The primary way to check for support of the instruction is to flip the ID - * bin in EFLAGS and then check if this changed was accepted. If so, the CPU - * supports the CPUID instruction, otherwise it most-likely doesn't. - */ -assert_cpuid_instruction_is_supported: - pushfl - pop %eax - mov %eax, %ecx - - xor $(1 << 21), %eax /* Flip the ID bit */ - push %eax /* Move the new bitset on the stack for loading */ - popfl /* Load the flags with ID set back into EFLAGS */ - pushfl /* Copy the flags back onto the stack */ - pop %eax /* Load the flags for further checking */ - - push %ecx - popfl - - cmp %ecx, %eax - je .Lcpuid_assertion_fail - ret -.Lcpuid_assertion_fail: - push $message_cpuid_instruction_no_supported - call _panic - -/** - * Assert that we were loaded by a Multiboot 2 compliant bootloader. - * - * This assertion will panic the system if the magic signature was not found. - * If we were loaded my an appropriate bootloader, this function also saves - * the provided MBI pointer to `multiboot_information_pointer`. - */ -assert_loaded_by_multiboot2_loader: - cmp $0x36d76289, %eax /* Check if we received the - expected magic */ - jne .Lmultiboot2_assertion_fail /* Panic otherwise */ - mov %ebx, multiboot_information_pointer /* Store the MBI pointer */ - ret -.Lmultiboot2_assertion_fail: - push $message_not_loaded_by_multiboot2 - call _panic - -/** - * Enable paging. - * - * Note: This routine expects for there to be a valid set of page maps already - * set up for use. - */ -enable_paging: - mov $page_map_level_4, %eax - mov %eax, %cr3 - - /* Enable Physical Address Extension */ - mov %cr4, %eax - or $(1 << 5), %eax - mov %eax, %cr4 - - /* Enable long mode support */ - mov $0xC0000080, %ecx - rdmsr - or $(1 << 8), %eax - wrmsr - - /* Enable paging */ - mov %cr0, %eax - or $(1 << 31), %eax - mov %eax, %cr0 - - ret - -/** - * Enable use of SSE instructions. - */ -enable_sse: - mov %cr0, %eax - and $0xfffffffb, %eax - or $0x00000002, %eax - mov %eax, %cr0 - - mov %cr4, %eax - or $(3 << 9), %eax - mov %eax, %cr4 - - ret - -/** - * Prepare the page maps. - * - * We map all physical memory we were loaded in plus one additional page. The - * mapping is done in terms of huge pages (2 MiB per page) to save on required - * page map entries. - */ -prepare_page_maps: - /* Map the P4 table recursively */ - mov $page_map_level_4, %eax - or $0b11, %eax /* Write present + writable flags into eax register */ - mov %eax, (page_map_level_4 + 511 * 8) - - /* Add an entry to the PML4, pointing to the PML3 */ - mov $page_map_level_3, %eax - or $0x3, %eax - mov %eax, (page_map_level_4 + ((0x0000000000100000 >> 39) & 0x1ff) * 8) - - /* Add an entry to the PML3, pointing to the PML2 */ - mov $page_map_level_2, %eax - or $0x3, %eax - mov %eax, (page_map_level_3 + ((0x0000000000100000 >> 30) & 0x1ff) * 8) - - xor %ecx, %ecx - - mov $_end_linear, %esi - shr $21, %esi - add $2, %esi - -.Lmap_pages: - mov $(1 << 21), %eax - mul %ecx - or $((1 << 0) | (1 << 1) | (1 << 7)), %eax - mov %eax, page_map_level_2(,%ecx,8) - - inc %ecx - cmp %esi, %ecx - jne .Lmap_pages - - ret - -.section .boot_text, "ax", @progbits -.code64 - -_transition_to_long_mode: - xor %rax, %rax - mov %rax, %ss - mov %rax, %ds - mov %rax, %es - mov %rax, %fs - mov %rax, %gs - - movl $0xb8000, (vga_buffer_pointer) - - call _init - - call kernel_main - call halt diff --git a/arch/x86_64/src/boot/boot32.S b/arch/x86_64/src/boot/boot32.S new file mode 100644 index 0000000..79b3ec7 --- /dev/null +++ b/arch/x86_64/src/boot/boot32.S @@ -0,0 +1,449 @@ +#include "x86_64/boot/boot.hpp" + +/** + * @brief Uninitialized data for the bootstrapping process. + */ +.section .boot_bss, "aw", @nobits + +/** + * @brief Storage for the multiboot2 information pointer. + */ +.global multiboot_information_pointer +multiboot_information_pointer: .skip 8 + +.align 4096 + +page_maps_start: +page_map_level_4: .skip 512 * 8 +page_map_level_3_high: .skip 512 * 8 +page_map_level_3_low: .skip 512 * 8 +page_map_level_2: .skip 512 * 8 +page_maps_end = . +page_maps_size = page_maps_end - page_maps_start + +/** + * @brief Storage for the bootstrap stack. + */ +.section .boot_stack, "aw", @nobits +.align 16 + +early_stack_bottom: .skip 1 << 8 +early_stack_top: +early_stack_size = early_stack_top - early_stack_bottom + +/** + * @brief Constants for the bootstrapping process. + */ +.section .boot_rodata, "a", @progbits + +.global global_descriptor_table_data + +/** + * @brief A basic GDT for long mode. + */ +global_descriptor_table: +global_descriptor_table_null = . - global_descriptor_table +.quad 0 +global_descriptor_table_code = . - global_descriptor_table +.quad GDT_READ_WRITE | GDT_EXECUTABLE | GDT_DESCRIPTOR_TYPE | GDT_PRESENT | GDT_LONG_MODE | (1 << 55) +global_descriptor_table_data = . - global_descriptor_table +.quad GDT_READ_WRITE | GDT_DESCRIPTOR_TYPE | GDT_PRESENT | (1 << 54) | (1 << 55) +global_descriptor_table_end: + +message_prefix_panic: .string "Panic: " +message_not_loaded_by_multiboot2: .string "The operating system was not loaded by a Multiboot 2 loader." +message_cpuid_instruction_no_supported: .string "The 'cpuid' instruction is not supported on this platform." +message_long_mode_not_supported: .string "Long mode is not supported by this platform." +message_return_from_kernel_main: .string "Execution returned from kernel main." + +/** + * @brief Initialized data for the bootstrapping process. + */ +.section .boot_data, "aw", @progbits + +/** + * @brief A pointer to the current position within the VGA text buffer. + */ +.global vga_buffer_pointer +vga_buffer_pointer: .quad 0xb8000 + +/** + * @brief Code for the bootstrapping process. + */ +.section .boot_text, "ax", @progbits +.align 16 +.code32 + +.macro pie_base + push %esi + call 0f + 0: + pop %esi +.endm + +.macro function_start + push %ebp + mov %esp, %ebp +.endm + +.macro function_end + leave + ret +.endm + +.macro pie_function_start + function_start + pie_base +.endm + +.macro pie_function_end + pop %esi + function_end +.endm + +/** + * @brief Prepare the environment and start the kernel. + * + * This function performs all necessary checks to ensure the system was loaded + * by the expected loader and supports all features required to run the kernel. + * If successful, it prepares the system by setting up memory virtualization + * and then start the kernel proper. + * + * @param %eax The Multiboot 2 magic marker. + * @param %ebx The Multiboot 2 information pointer. + * @return void This function does not return. + */ +.global _start +_start: + call 0f +0: + pop %esi + + lea (early_stack_top - 0b)(%esi), %ecx + + mov %ecx, %esp + mov %esp, %ebp + + call _assert_loaded_by_multiboot2_loader + call _save_multiboot_information_pointer + + call _assert_cpuid_instruction_is_supported + call _assert_cpu_supports_long_mode + + push $HUGE_PAGES_TO_MAP + call _prepare_page_maps + add $4, %esp + + call _enable_paging + call _enable_sse + call _reload_gdt + + lea (_entry64 - 0b)(%esi), %eax + pushl $global_descriptor_table_code + pushl %eax + lret + +/** + * @brief Halt the system. + * + * This function will instruct the CPU to halt. It will try to keep the CPU + * halted, even if interrupts occur. + * + * @return This function never returns. + */ +_halt: + function_start + +1: + hlt + jmp 1b + + function_end + +/** + * @brief Print a message via the VGA text buffer. + * + * @param ebp+12 The message to print. + * @param ebp+8 The color to print the message in. + */ +_print: + pie_function_start + + push %edi + push %ebx + + mov 8(%ebp), %al + mov 12(%ebp), %edx + mov $0, %ecx + lea (vga_buffer_pointer - 0b)(%esi), %edi + mov (%edi), %edi + +1: + mov (%edx, %ecx), %bl + test %bl, %bl + je 2f + mov %bl, (%edi, %ecx, 2) + mov %al, 1(%edi, %ecx, 2) + inc %ecx + jmp 1b + +2: + shl $1, %ecx + add %ecx, %edi + lea (vga_buffer_pointer - 0b)(%esi), %ecx + mov %edi, (%ecx) + + pop %ebx + pop %edi + + pie_function_end + +/** + * @brief Print a given panic message and then halt the machine as if by calling ::halt() + * + * @param ebp+4 A message to print. + * @return This function does not return. + */ +_panic: + pie_function_start + + lea (message_prefix_panic - 0b)(%esi), %eax + + push %eax + push $0x4f + call _print + + mov 16(%ebp), %eax + mov %eax, 8(%ebp) + call _print + add $8, %esp + + call _halt + + pie_function_end + +/** + * Assert that we were loaded by a Multiboot 2 compliant bootloader. + * + * This assertion will panic the system if the magic signature was not found. + * If we were loaded my an appropriate bootloader, this function also saves + * the provided MBI pointer to `multiboot_information_pointer`. + */ +_assert_loaded_by_multiboot2_loader: + pie_function_start + + cmp $MULTIBOOT2_MAGIC, %eax + je 1f + lea (message_not_loaded_by_multiboot2 - 0b)(%esi), %eax + push %eax + call _panic +1: + pie_function_end + +/** + * @brief Store the multiboot 2 information pointer in the global memory. + * + * @return void + */ +_save_multiboot_information_pointer: + pie_function_start + + lea (multiboot_information_pointer - 0b)(%esi), %eax + mov %ebx, (%eax) + + pie_function_end + +/** + * @brief Assert that the CPU supports the CPUID instruction. + * + * The primary way to check for support of the instruction is to flip the ID + * bin in EFLAGS and then check if this changed was accepted. If so, the CPU + * supports the CPUID instruction, otherwise it most-likely doesn't. + */ +_assert_cpuid_instruction_is_supported: + pie_function_start + + pushfl + pop %eax + mov %eax, %ecx + + xor $(1 << 21), %eax /* Flip the ID bit */ + push %eax /* Move the new bitset on the stack for loading */ + popfl /* Load the flags with ID set back into EFLAGS */ + pushfl /* Copy the flags back onto the stack */ + pop %eax /* Load the flags for further checking */ + + push %ecx + popfl + + cmp %ecx, %eax + jne 1f + lea (message_cpuid_instruction_no_supported - 0b)(%esi), %eax + push %eax + call _panic + +1: + pie_function_end + +/** + * @brief Assert that the CPU supports going into long mode. + */ +_assert_cpu_supports_long_mode: + pie_function_start + + mov $0x80000000, %eax + cpuid + cmp $0x80000001, %eax + jb 1f + + mov $0x80000001, %eax + cpuid + test $(1 << 29), %edx + jnz 2f +1: + lea (message_long_mode_not_supported - 0b)(%esi), %eax + push %eax + call _panic +2: + pie_function_end + +/** + * @brief Prepare a recursive page map hierarchy + * + * @param ebp+8 The number of huge pages to map + * @return void + */ +_prepare_page_maps: + pie_function_start + + push %edi + + call _clear_page_map_memory + + lea (page_map_level_4 - 0b)(%esi), %edi + mov %edi, %eax + or $0b11, %eax + mov %eax, (510 * 8)(%edi) + + lea (page_map_level_3_low - 0b)(%esi), %eax + or $0b11, %eax + mov %eax, (%edi) + + lea (page_map_level_3_high - 0b)(%esi), %eax + or $0b11, %eax + mov %eax, (511 * 8)(%edi) + + lea (page_map_level_3_low - 0b)(%esi), %edi + lea (page_map_level_2 - 0b)(%esi), %eax + or $0b11, %eax + mov %eax, (%edi) + + lea (page_map_level_3_high - 0b)(%esi), %edi + lea (page_map_level_2 - 0b)(%esi), %eax + or $0b11, %eax + mov %eax, (510 * 8)(%edi) + + lea (page_map_level_2 - 0b)(%esi), %edi + mov 8(%ebp), %ecx + +1: + dec %ecx + mov $(1 << 21), %eax + mul %ecx + or $0b10000011, %eax + mov %eax, (%edi, %ecx, 8) + + test %ecx, %ecx + jnz 1b + + pop %edi + + pie_function_end + +/** + * @brief Clear all page map memory by filling it with 0s. + * + * @return void + */ +_clear_page_map_memory: + pie_function_start + + push %edi + + xor %eax, %eax + mov $page_maps_size, %ecx + shr $2, %ecx + lea (page_maps_start - 0b)(%esi), %edi + rep stosl + + pop %edi + + pie_function_end + +/** + * @p Enable memory virtualization via paging. + * + * Note: This routine expects for there to be a valid set of page maps already + * set up for use. + * + * @return void + */ +_enable_paging: + pie_function_start + + lea (page_map_level_4 - 0b)(%esi), %eax + mov %eax, %cr3 + + /* Enable Physical Address Extension */ + mov %cr4, %eax + or $(1 << 5), %eax + mov %eax, %cr4 + + /* Enable long mode support */ + mov $0xC0000080, %ecx + rdmsr + or $(1 << 8), %eax + wrmsr + + /* Enable paging */ + mov %cr0, %eax + or $(1 << 31), %eax + mov %eax, %cr0 + + pie_function_end + +/** + * @brief Enable use of SSE instructions. + */ +_enable_sse: + function_start + + mov %cr0, %eax + and $0xfffffffb, %eax + or $0x00000002, %eax + mov %eax, %cr0 + + mov %cr4, %eax + or $(3 << 9), %eax + mov %eax, %cr4 + + function_end + +/** + * @brief Prepare a new GTD and load make it active. + * + * @return void + */ +_reload_gdt: + pie_function_start + + sub $10, %esp + lea (global_descriptor_table - 0b)(%esi), %eax + movw $(global_descriptor_table_end - global_descriptor_table -1), (%esp) + mov %eax, 2(%esp) + movl $0, 6(%esp) + + lgdt (%esp) + add $10, %esp + + pie_function_end diff --git a/arch/x86_64/src/boot/crti.s b/arch/x86_64/src/boot/crti.s deleted file mode 100644 index 26878fe..0000000 --- a/arch/x86_64/src/boot/crti.s +++ /dev/null @@ -1,13 +0,0 @@ -.code64 - -.section .init -.global _init -_init: - push %rbp - movq %rsp, %rbp - -.section .fini -.global _fini -_fini: - push %rbp - movq %rsp, %rbp diff --git a/arch/x86_64/src/boot/crtn.s b/arch/x86_64/src/boot/crtn.s deleted file mode 100644 index 06fb7ce..0000000 --- a/arch/x86_64/src/boot/crtn.s +++ /dev/null @@ -1,9 +0,0 @@ -.code64 - -.section .init - popq %rbp - ret - -.section .fini - popq %rbp - ret diff --git a/arch/x86_64/src/boot/entry64.s b/arch/x86_64/src/boot/entry64.s new file mode 100644 index 0000000..657b0a8 --- /dev/null +++ b/arch/x86_64/src/boot/entry64.s @@ -0,0 +1,60 @@ +.section .bss, "aw", @nobits + +//! A structure containing information gathered during the bootstrap process. +//! Expected layout (as described by teachos::boot::information): +//! +//! struct +//! { +//! multiboot2::information_view const * mbi; +//! std::size_t vga_buffer_index; +//! } +.global bootstrap_information +bootstrap_information: .skip 16 + +.align 16 +.global stack_top +stack_bottom: .skip 1 << 20 +stack_top: +stack_size = stack_top - stack_bottom + +.section .boot_text, "ax", @progbits +.code64 + +.global _entry64 +_entry64: + mov $global_descriptor_table_data, %rax + mov %rax, %ss + mov %rax, %ds + mov %rax, %es + mov %rax, %fs + mov %rax, %gs + + mov $stack_top, %rsp + mov %rsp, %rbp + + mov multiboot_information_pointer, %rax + or $TEACHOS_VMA, %rax + mov vga_buffer_pointer, %rdx + sub $0xb8000, %rdx + mov %rax, (bootstrap_information) + mov %rdx, (bootstrap_information + 8) + + call invoke_global_constructors + + xor %rax, %rax + mov %rax, %rbp + mov %rax, %rdx + mov %rax, %rsi + + mov $stack_size, %rcx + shr $3, %rcx + lea (stack_bottom), %rdi + rep stosq + + mov %rax, %rdi + + call main + +1: + hlt + jmp 1b diff --git a/arch/x86_64/src/boot/initialize_runtime.cpp b/arch/x86_64/src/boot/initialize_runtime.cpp new file mode 100644 index 0000000..46dd5e4 --- /dev/null +++ b/arch/x86_64/src/boot/initialize_runtime.cpp @@ -0,0 +1,26 @@ +#include <algorithm> +#include <functional> +#include <span> + +extern "C" +{ + using global_initializer = auto (*)() -> void; + + extern global_initializer __ctors_start; + extern global_initializer __ctors_end; + extern global_initializer __init_array_start; + extern global_initializer __init_array_end; + + auto invoke_global_constructors() -> void + { + auto constructors = std::span{&__ctors_start, &__ctors_end}; + auto initializers = std::span{&__init_array_start, &__init_array_end}; + + auto apply_invoke = [](auto invokable) -> void { + std::invoke(invokable); + }; + + std::ranges::for_each(constructors, apply_invoke); + std::ranges::for_each(initializers, apply_invoke); + } +} |