ext/caos-with-snake
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Enable int 0x84 from userspace.

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This commit is contained in:
Alexander Myltsev 2022-12-14 12:43:33 +03:00
parent 5f3cbb988d
commit 069625a6e0
2 changed files with 16 additions and 6 deletions
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21
cpu/idt.c
View File

@ -1,4 +1,5 @@
#include "isr.h"
#include "gdt.h"
#include "../drivers/port.h"
#include "../console.h"
@ -10,7 +11,10 @@ typedef struct {
uint16_t low_offset;
uint16_t selector;
uint8_t always0;
uint8_t flags;
uint8_t type: 4;
uint8_t s: 1;
uint8_t dpl: 2;
uint8_t p: 1;
uint16_t high_offset;
} __attribute__((packed)) idt_gate_t;
@ -19,13 +23,17 @@ idt_gate_t idt[IDT_HANDLERS];
#define low_16(address) (uint16_t)((address) & 0xFFFF)
#define high_16(address) (uint16_t)(((address) >> 16) & 0xFFFF)
void set_idt_gate(int n, uint32_t handler) {
#define STS_IG32 0xE // 32-bit Interrupt Gate
#define STS_TG32 0xF // 32-bit Trap Gate
void set_idt_gate(int n, _Bool istrap, uint32_t handler, uint8_t dpl) {
idt[n].low_offset = low_16(handler);
idt[n].selector = 0x08; // see GDT
idt[n].always0 = 0;
// 0x8E = 1 00 0 1 110
// P DPL 0 D Type
idt[n].flags = 0x8E;
idt[n].type = istrap ? STS_TG32 : STS_IG32;
idt[n].s = 0;
idt[n].dpl = dpl;
idt[n].p = 1;
idt[n].high_offset = high_16(handler);
}
@ -37,8 +45,9 @@ void init_idt() {
panic("handler table empty\n");
}
for (int i = 0; i < IDT_HANDLERS; i++) {
set_idt_gate(i, default_handlers[i]);
set_idt_gate(i, 0, default_handlers[i], 0);
}
set_idt_gate(T_SYSCALL, 1, default_handlers[T_SYSCALL], DPL_USER);
}
const char * const exception_messages[] = {

1
cpu/isr.h
View File

@ -18,6 +18,7 @@ enum {
IRQ13,
IRQ14,
IRQ15,
T_SYSCALL = 0x84,
};
/* Struct which aggregates many registers.