Merge branch 'fmorgner/develop-BA-FS26/gdt_idt' into develop-BA-FS26

This patchset enables the use of interrupts. Specifically, it simplifies
debugging by printing the fault address in case of a page fault.

1 files changed, 120 insertions, 0 deletions

diff --git a/arch/x86_64/src/cpu/interrupts.cpp b/arch/x86_64/src/cpu/interrupts.cpp
new file mode 100644
index 0000000..466389d
--- /dev/null
+++ b/arch/x86_64/src/cpu/interrupts.cpp
@@ -0,0 +1,120 @@
+#include "arch/cpu/interrupts.hpp"
+
+#include "kapi/cpu.hpp"
+
+#include "arch/cpu/segment_selector.hpp"
+
+#include <kstd/print>
+
+#include <cstdint>
+
+namespace arch::cpu
+{
+
+  namespace
+  {
+    constexpr auto isr_number_page_fault = 0x0e;
+    constexpr auto isr_number_legacy_start = 0x20;
+    constexpr auto isr_number_legacy_end = 0x29;
+    constexpr auto isr_number_cascade_start = 0x2c;
+    constexpr auto isr_number_cascade_end = 0x2f;
+
+    auto handle_page_fault(interrupt_frame * frame) -> void
+    {
+      auto fault_address = std::uintptr_t{};
+      asm volatile("mov %%cr2, %0" : "=r"(fault_address));
+
+      auto const present = (frame->interrupt.error_code & 0x1) != 0;
+      auto const write = (frame->interrupt.error_code & 0x2) != 0;
+      auto const user = (frame->interrupt.error_code & 0x4) != 0;
+
+      kstd::println(kstd::print_sink::stderr, "[x86_64:MMU] PAGE FAULT!");
+      kstd::println(kstd::print_sink::stderr, "\tFault address: {:#018x}", fault_address);
+      kstd::println(kstd::print_sink::stderr, "\tPresent: {}", present);
+      kstd::println(kstd::print_sink::stderr, "\tWrite: {}", write);
+      kstd::println(kstd::print_sink::stderr, "\tUser: {}", user);
+      kstd::println(kstd::print_sink::stderr, "\tRIP: {:#018x}", frame->cpu_saved.rip);
+      kstd::println(kstd::print_sink::stderr, "\tHalting the system now!");
+
+      kapi::cpu::halt();
+    }
+
+    auto handle_legacy_interrupt(interrupt_frame * frame) -> void
+    {
+      kstd::println("[x86_64:SYS] Ignoring 8259 legacy interrupt {:#04x}", frame->interrupt.number);
+    }
+  }  // namespace
+
+  extern "C"
+  {
+    extern std::uintptr_t const isr_stub_table[256];
+
+    auto interrupt_dispatch(interrupt_frame * frame) -> void
+    {
+      if ((frame->interrupt.number >= isr_number_legacy_start && frame->interrupt.number <= isr_number_legacy_end) ||
+          (frame->interrupt.number >= isr_number_cascade_start && frame->interrupt.number <= isr_number_cascade_end))
+      {
+        handle_legacy_interrupt(frame);
+        return;
+      }
+
+      switch (frame->interrupt.number)
+      {
+        case isr_number_page_fault:
+          handle_page_fault(frame);
+          break;
+        default:
+          kstd::println(kstd::print_sink::stderr, "[x86_64:SYS] Unhandled interrupt {:#04x} received with code {:#04x}",
+                        frame->interrupt.number, frame->interrupt.error_code);
+          kapi::cpu::halt();
+      }
+    }
+  }
+
+  interrupt_descriptor_table::interrupt_descriptor_table() noexcept
+  {
+    for (auto i = 0uz; i < 256; ++i)
+    {
+      m_descriptors[i] = gate_descriptor{
+        .offset_low = static_cast<std::uint16_t>(isr_stub_table[i] & 0xffff), // NOLINT(readability-magic-numbers)
+        .m_code_segment = segment_selector{0, false, 1},
+        .interrupt_stack_table_selector = 0,
+        .gate_type = gate_type::interrupt_gate,
+        .descriptor_privilege_level = 0,
+        .present = true,
+        .offset_middle =
+            static_cast<std::uint16_t>((isr_stub_table[i] >> 16) & 0xffff), // NOLINT(readability-magic-numbers)
+        .offset_high =
+            static_cast<std::uint32_t>((isr_stub_table[i] >> 32) & 0xffff'ffff), // NOLINT(readability-magic-numbers)
+      };
+    }
+  }
+
+  auto interrupt_descriptor_table::load() const -> void
+  {
+    interrupt_descriptor_table_register{.limit = sizeof(m_descriptors) - 1, .base = m_descriptors.data()}.load();
+  }
+
+  auto interrupt_descriptor_table_register::load() const -> void
+  {
+    asm volatile("lidt %0" : : "m"(*this));
+  }
+
+  auto interrupt_descriptor_table_register::read() -> interrupt_descriptor_table_register
+  {
+    interrupt_descriptor_table_register idtr{};
+    asm volatile("sidt %0" : : "m"(idtr));
+    return idtr;
+  }
+
+  auto enable_interrupts() -> void
+  {
+    asm volatile("sti");
+  }
+
+  auto disable_interrupts() -> void
+  {
+    asm volatile("cli");
+  }
+
+}  // namespace arch::cpu
\ No newline at end of file