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#include "arch/context_switching/main.hpp"
#include "arch/boot/pointers.hpp"
#include "arch/exception_handling/assert.hpp"
#include "arch/kernel/cpu/if.hpp"
#include "arch/kernel/cpu/jmp.hpp"
#include "arch/kernel/cpu/tr.hpp"
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));
// 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.");
// 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;
}
} // namespace teachos::arch::context_switching
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