nadir-kernel/include/idt.h

66 lines
2.1 KiB
C

/* Nadir interrupt IDT + CPU exception entry points.
*
* Runs in 64-bit long mode at Ring 0 (CPL 0) with the stage-2 GDT.
* Privileged primitive: `lidt` in idt_init(). Fault behavior: before
* idt_init() any exception triple-faults (no IDT); after, CPU vectors
* 0-31 land in the assembly stubs (isr.asm) and then in
* exception_handler(), which prints and halts. Vectors 32-255 are left
* zero (not present) on purpose because PIC remap + IRQ handling is a later step.
* Interrupts stay disabled throughout (IF=0); exceptions still fire.
*/
#ifndef NADIR_IDT_H
#define NADIR_IDT_H
#include <stdint.h>
/* Number of CPU exception vectors this base installs (0-31). */
#define IDT_EXCEPTION_COUNT 32
/* Stack layout on entry to exception_handler().
*
* Built by the CPU (RIP/CS/RFLAGS, plus an error code on vectors
* 8, 10-14, 17, 21) plus isr.asm: the stub normalizes the stack to
* [vector, error] and isr_common pushes the 15 general-purpose
* registers. RDI points at this struct (System V first argument).
* Field order matches the push order in isr_common — keep in sync.
*/
struct interrupt_frame {
uint64_t r15;
uint64_t r14;
uint64_t r13;
uint64_t r12;
uint64_t r11;
uint64_t r10;
uint64_t r9;
uint64_t r8;
uint64_t rbp;
uint64_t rdi;
uint64_t rsi;
uint64_t rdx;
uint64_t rcx;
uint64_t rbx;
uint64_t rax;
/* Pushed by the stub: exception vector 0-31. */
uint64_t vector;
/* CPU-pushed error code, or 0 inserted by the stub. */
uint64_t error;
/* Pushed by the CPU. */
uint64_t rip;
uint64_t cs;
uint64_t rflags;
/* Pushed by the CPU only on a privilege change; garbage for
* kernel-mode faults */
uint64_t rsp;
uint64_t ss;
};
/* Build the IDT (vectors 0-31 -> isr stubs) and load it with `lidt`.
* Ring 0 only. Leaves IF cleared; returns with exceptions catchable. */
void idt_init(void);
/* C entry point for vectors 0-31, called from isr_common with the
* frame above. Prints vector/error/RIP and halts; never returns. */
void exception_handler(struct interrupt_frame *frame);
#endif /* NADIR_IDT_H */