idt.cpp

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// SPDX-License-Identifier: GPL-3.0-or-later
 
#include "mos/x86/descriptors/descriptors.hpp"
 
#include <mos/platform/platform.hpp>
#include <mos/x86/x86_interrupt.hpp>
#include <mos/x86/x86_platform.hpp>
 
static idt_entry_t idt[IDT_ENTRY_COUNT] __aligned(16) = { 0 };
static idtr_t idtr;
 
#define IDT_FLAG_P (1 << 7)
 
#define STS_IG32 0xE // 32-bit Interrupt Gate
#define STS_TG32 0xF // 32-bit Trap Gate
 
extern "C" void idt_flush(idtr_t *idtr);
 
static void idt_set_descriptor(u8 vector, void *isr, bool usermode, bool is_trap)
{
    idt_entry_t *descriptor = &idt[vector];
 
    descriptor->isr_veryhigh = (uintn) isr >> 32;
    descriptor->reserved2 = 0;
 
    descriptor->isr_low = (uintn) isr & 0xFFFF;
    descriptor->isr_high = (uintn) isr >> 16;
    descriptor->segment = GDT_SEGMENT_KCODE;
    descriptor->present = true;
    descriptor->dpl = usermode ? 3 : 0;
    descriptor->type = is_trap ? STS_TG32 : STS_IG32;
    descriptor->zero = 0;
    descriptor->reserved = 0;
}
 
void x86_init_percpu_idt()
{
    idt_flush(&idtr);
}
 
void x86_idt_init()
{
    for (u8 isr = 0; isr < ISR_MAX_COUNT; isr++)
        idt_set_descriptor(isr, isr_stub_table[isr], false, false);
 
    for (u8 irq_n = 0; irq_n < IRQ_MAX_COUNT; irq_n++)
        idt_set_descriptor(irq_n + IRQ_BASE, irq_stub_table[irq_n], false, false);
 
    // system calls
    idt_set_descriptor(MOS_SYSCALL_INTR, isr_stub_table[MOS_SYSCALL_INTR], true, true);
 
    for (u8 ipi_n = 0; ipi_n < IPI_TYPE_MAX; ipi_n++)
        idt_set_descriptor(ipi_n + IPI_BASE, isr_stub_table[ipi_n + IPI_BASE], false, false);
 
    idtr.base = &idt[0];
    idtr.limit = (u16) sizeof(idt_entry_t) * IDT_ENTRY_COUNT - 1;
}