fix gdt segments, improve idt and trial&error for triple fault

7 files changed, 46 insertions, 32 deletions

diff --git a/arch/x86_64/src/boot/boot.s b/arch/x86_64/src/boot/boot.s
index 108dbe5..38a8af4 100644
--- a/arch/x86_64/src/boot/boot.s
+++ b/arch/x86_64/src/boot/boot.s
@@ -197,10 +197,8 @@ _start:
     call enable_paging
     call enable_sse
 
-    cli /* Clears the interrupt flag during the GDT setup */
     lgdt (global_descriptor_table_pointer)
     jmp $global_descriptor_table_code, $_transition_to_long_mode
-    /* The interrupt flag is set in cpp after setting up the GDT */
 
     call halt
 
@@ -369,14 +367,7 @@ reload_segment_register:
     ret
 
 _transition_to_long_mode:
-    //call reload_segment_register
-
-    xor %rax, %rax
-    mov %rax, %ss
-    mov %rax, %ds
-    mov %rax, %es
-    mov %rax, %fs
-    mov %rax, %gs
+    call reload_segment_register
 
     movl $0xb8000, (vga_buffer_pointer)
 
diff --git a/arch/x86_64/src/context_switching/interrupt_descriptor_table/gate_descriptor.cpp b/arch/x86_64/src/context_switching/interrupt_descriptor_table/gate_descriptor.cpp
index 28f289c..d86c459 100644
--- a/arch/x86_64/src/context_switching/interrupt_descriptor_table/gate_descriptor.cpp
+++ b/arch/x86_64/src/context_switching/interrupt_descriptor_table/gate_descriptor.cpp
@@ -8,6 +8,7 @@ namespace teachos::arch::context_switching::interrupt_descriptor_table
       , _ist(flags >> 32U)
       , _flags(flags >> 40U)
       , _offset_2(flags >> 48U)
+      , _offset_3(flags >> 64U)
   {
     // Nothing to do.
   }
@@ -18,6 +19,7 @@ namespace teachos::arch::context_switching::interrupt_descriptor_table
       , _ist(ist)
       , _flags(flags)
       , _offset_2(offset >> 16U)
+      , _offset_3(offset >> 48U)
   {
     // Nothing to do.
   }
diff --git a/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp b/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp
index ddc098e..1c1de68 100644
--- a/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp
+++ b/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp
@@ -1,20 +1,24 @@
 #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
   {
+
     auto create_interrupt_descriptor_table() -> interrupt_descriptor_table
     {
-      uint64_t offset = 0U;
+      // @MTO: This address resolution is most certainly wrong -> numbers in dbg seem off (offset_3 = 0)
+      uint64_t offset = reinterpret_cast<uint64_t>(&interrupt_handling::generic_interrupt_handler);
       segment_selector selector{0U, segment_selector::REQUEST_LEVEL_KERNEL};
       ist_offset ist{0U};
-      idt_flags flags{idt_flags::DESCRIPTOR_LEVEL_KERNEL};
-      gate_descriptor gate_descriptor{selector, ist, flags, offset};
-      return interrupt_descriptor_table{gate_descriptor};
+      idt_flags flags{idt_flags::DESCRIPTOR_LEVEL_KERNEL | idt_flags::PRESENT};
+      gate_descriptor descriptor{selector, ist, flags, offset};
+
+      return interrupt_descriptor_table{descriptor};
     }
   }  // namespace
 
@@ -24,7 +28,7 @@ namespace teachos::arch::context_switching::interrupt_descriptor_table
     static auto idt = create_interrupt_descriptor_table();
 
     interrupt_descriptor_table_pointer idt_pointer{static_cast<uint16_t>((idt.size() * sizeof(gate_descriptor)) - 1),
-                                                   &idt};
+                                                   idt.data()};
     kernel::cpu::load_interrupt_descriptor_table(idt_pointer);
 
     auto const stored_gdt_pointer = kernel::cpu::store_interrupt_descriptor_table();
diff --git a/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.cpp b/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.cpp
index 981944d..7bcbae6 100644
--- a/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.cpp
+++ b/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.cpp
@@ -3,7 +3,7 @@
 namespace teachos::arch::context_switching::interrupt_descriptor_table
 {
   interrupt_descriptor_table_pointer::interrupt_descriptor_table_pointer(uint16_t table_length,
-                                                                         interrupt_descriptor_table * address)
+                                                                         gate_descriptor * address)
       : table_length(table_length)
       , address(address)
   {
diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index a5bd3fb..f449a3a 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -10,24 +10,30 @@ namespace teachos::arch::context_switching
 {
   auto initialize_descriptor_tables() -> descriptor_tables
   {
+    kernel::cpu::clear_interrupt_flag();
     decltype(auto) global_descriptor_table = segment_descriptor_table::initialize_global_descriptor_table();
     decltype(auto) interrupt_descriptor_table = interrupt_descriptor_table::initialize_interrupt_descriptor_table();
 
-    kernel::cpu::far_pointer pointer{&boot::reload_segment_register, 1 * sizeof(segment_descriptor_table::segment_descriptor)};
-    asm volatile("rex64 lcall *%[far_function_pointer]" : : [far_function_pointer] "m" (pointer));
+    kernel::cpu::far_pointer pointer{&boot::reload_segment_register,
+                                     1 * sizeof(segment_descriptor_table::segment_descriptor)};
+    asm volatile("rex64 lcall *%[far_function_pointer]" : : [far_function_pointer] "m"(pointer));
 
-    // // 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 * 16) = 80
-    // uint16_t const tss_selector =
-    //     (global_descriptor_table.size() - 1) * sizeof(segment_descriptor_table::segment_descriptor);
-    // kernel::cpu::load_task_register(tss_selector);
+    // 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 * 16) = 80
+    uint16_t const tss_selector =
+        (global_descriptor_table.size() - 1) * sizeof(segment_descriptor_table::segment_descriptor);
+    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.");
+    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.");
 
-    // FIXME: We currently cannot enable interrupts, since for some reason, we will later run into what looks like a GP. Maybe because no IDT is loaded? Maybe our boot code segment is not set up correctly?
-    // kernel::cpu::set_interrupt_flag();
+    // FIXME: We currently cannot enable interrupts, since for some reason, we will later run into what looks like a GP
+    // and triple fault.
+
+    // @MTO: SOMETIMES i get past a breakpoint here???? seems to happen when i actually pause before (f.e. inside the
+    // idt). NEVER happened when stepping through quickly. Can you reproduce this?
+    kernel::cpu::set_interrupt_flag();
 
     descriptor_tables tables = {global_descriptor_table, interrupt_descriptor_table};
     return tables;
diff --git a/arch/x86_64/src/context_switching/segment_descriptor_table/global_descriptor_table.cpp b/arch/x86_64/src/context_switching/segment_descriptor_table/global_descriptor_table.cpp
index 37ee778..d9ad91c 100644
--- a/arch/x86_64/src/context_switching/segment_descriptor_table/global_descriptor_table.cpp
+++ b/arch/x86_64/src/context_switching/segment_descriptor_table/global_descriptor_table.cpp
@@ -17,17 +17,14 @@ namespace teachos::arch::context_switching::segment_descriptor_table
     {
       uint8_t access_level_bits =
           access_byte::PRESENT | access_byte::CODE_OR_DATA_SEGMENT | *reinterpret_cast<uint8_t *>(&access_level);
-      uint8_t gdt_flags_bits = gdt_flags::GRANULARITY;
+      uint8_t gdt_flags_bits = gdt_flags::GRANULARITY | gdt_flags::LONG_MODE;
       if (segment_descriptor_type == segment_descriptor_type::CODE_SEGMENT)
       {
-        gdt_flags_bits |= gdt_flags::LONG_MODE;
         access_level_bits |= access_byte::CODE_SEGMENT | access_byte::READABLE;
       }
       else if (segment_descriptor_type == segment_descriptor_type::DATA_SEGMENT)
       {
         gdt_flags_bits |= 1 << 2;
-        // FIXME: Look at those bit flags, something seems off.
-        // gdt_flags_bits |= gdt_flags::UPPER_BOUND;
         access_level_bits |= access_byte::WRITABLE;
       }
 
diff --git a/arch/x86_64/src/interrupt_handling/generic_interrupt_handler.cpp b/arch/x86_64/src/interrupt_handling/generic_interrupt_handler.cpp
new file mode 100644
index 0000000..68b4568
--- /dev/null
+++ b/arch/x86_64/src/interrupt_handling/generic_interrupt_handler.cpp
@@ -0,0 +1,14 @@
+#include "arch/interrupt_handling/generic_interrupt_handler.hpp"
+
+#include "arch/video/vga/text.hpp"
+
+namespace teachos::arch::interrupt_handling
+{
+
+  [[gnu::interrupt]]
+  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);
+  }
+}  // namespace teachos::arch::interrupt_handling
\ No newline at end of file