diff options
Diffstat (limited to 'arch/x86_64/src/kernel/main.cpp')
| -rw-r--r-- | arch/x86_64/src/kernel/main.cpp | 76 |
1 files changed, 44 insertions, 32 deletions
diff --git a/arch/x86_64/src/kernel/main.cpp b/arch/x86_64/src/kernel/main.cpp index daaf216..ac2591e 100644 --- a/arch/x86_64/src/kernel/main.cpp +++ b/arch/x86_64/src/kernel/main.cpp @@ -50,33 +50,48 @@ namespace teachos::arch::kernel delete test9; } - [[gnu::naked]] - auto push_code_segment(context_switching::interrupt_descriptor_table::segment_selector segment_selector_a, - context_switching::interrupt_descriptor_table::segment_selector segment_selector_b) -> void + auto return_function() -> void { - asm volatile("push %%rbp\n" - "push %[input]" - : /* No output from call */ - : [input] "m"(segment_selector_a)); - asm volatile("mov %[input], %%ax\n" - "mov %%ax, %%ss\n" - "mov %%ax, %%ds\n" - "mov %%ax, %%es\n" - "mov %%ax, %%fs\n" - "mov %%ax, %%gs" - : /* No output from call */ - : [input] "m"(segment_selector_b)); - asm volatile("iretq" - : /* No output from call */ - : /* No input to call */); + video::vga::text::write("User Mode!!!", video::vga::text::common_attributes::green_on_black); } + /** + * @brief Switch context into the mode defined in the segment selectors. + * + * Setup the stack IRETQ expects to switch the mode: + * 1. push data selector + * 2. push current stack pointer + * 3. push eflags + * 4. push code segment selector + * 5. push return address + * + * @param data_segment + * @param code_segment + * @param address + */ [[gnu::naked]] - auto iret() -> void + auto switch_context(context_switching::interrupt_descriptor_table::segment_selector data_segment, + context_switching::interrupt_descriptor_table::segment_selector code_segment, uint64_t address) + -> void { - asm volatile("iretq" - : /* No output from call */ - : /* No input to call */); + asm volatile("mov %[data_segment], %%rax\n" + "mov %%rax, %%ds\n" + "mov %%rax, %%es\n" + "mov %%rax, %%fs\n" + "mov %%rax, %%gs\n" + "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" + : + : [data_segment] "m"(data_segment), [code_segment] "m"(code_segment), [return_function] "r"(address) + : "rax"); } auto main() -> void @@ -95,17 +110,14 @@ namespace teachos::arch::kernel decltype(auto) descriptor_tables = context_switching::initialize_descriptor_tables(); - // - Clear NT flag in EFLAGS register (for far return) - - // - Push return instruction pointer - // - Push return code segment selector - // context_switching::interrupt_descriptor_table::segment_selector user_code_segment_selector{ - // 3U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER}; - // context_switching::interrupt_descriptor_table::segment_selector user_data_segment_selector{ - // 4U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER}; - // push_code_segment(user_code_segment_selector, user_data_segment_selector); + context_switching::interrupt_descriptor_table::segment_selector user_code_segment_selector{ + 3U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER}; + context_switching::interrupt_descriptor_table::segment_selector user_data_segment_selector{ + 4U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER}; - boot::context_switch(); + cpu::set_segment_registers(user_data_segment_selector); + switch_context(user_data_segment_selector, user_code_segment_selector, + reinterpret_cast<uint64_t>(&return_function)); (void)descriptor_tables; } |