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GPT handler detects V86 mode; Interrupt printing fixes

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This commit is contained in:
Lucia Ceionia 2022-09-16 17:07:27 -05:00
parent 192d4f04ed
commit 8bfcd4fd19
5 changed files with 53 additions and 45 deletions
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2
entry.nasm
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@ -68,7 +68,7 @@ inc al
cmp eax, 200
jl .loop
xor ebx, ebx
div bl
div bl ; Unhandled DIV0 exception
global jmp_usermode_test
jmp_usermode_test:

11
handler.nasm
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@ -12,10 +12,14 @@ jmp .hlt
extern gpf_handler_v86
global gpfHandler
gpfHandler:
iret
push eax
mov ax, 0x10
mov ds, ax
;jmp gpf_handler_v86
mov eax, dword [esp+16] ; EFLAGS
and eax, 1 << 17 ; VM flag
test eax, eax
pop eax
jnz gpf_handler_v86
mov word [0xb8000], 0x0f00 | 'G'
mov word [0xb8002], 0x0f00 | 'P'
mov word [0xb8004], 0x0f00 | 'F'
@ -71,8 +75,7 @@ kbd_wait:
mov byte [KBDWAIT], 0
.loop:
hlt
xor eax, eax
mov al, [KBDWAIT]
movzx eax, byte [KBDWAIT]
test eax, eax
jz .loop
ret

74
interrupt.c
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@ -1,10 +1,26 @@
#include <stdint.h>
#include <stddef.h>
#include "print.h"
#include "interrupt.h"
char int_nibbleToHex(uint8_t n) {
return n > 9 ? (n - 10) + 'A' : n + '0';
}
void int_printByte(uint8_t v, uint16_t *buff) {
*(char *)&buff[0] = int_nibbleToHex((v >> 4) & 0xF);
*(char *)&buff[1] = int_nibbleToHex(v & 0xF);
}
__attribute((__no_caller_saved_registers__))
void int_printWord(uint16_t v, uint16_t *buff) {
int_printByte(v >> 8, buff);
int_printByte(v, &buff[2]);
}
__attribute((__no_caller_saved_registers__))
void int_printDword(uint32_t v, uint16_t *buff) {
int_printWord(v >> 16, buff);
int_printWord(v, &buff[4]);
}
struct __attribute__((__packed__)) IDTR_t {
uint16_t size;
uint32_t offset;
@ -74,7 +90,7 @@ extern void jmp_usermode_test();
#define VALID_FLAGS 0xDFF
__attribute__ ((interrupt))
void gpf_handler_v86(struct interrupt_frame *frame, unsigned long error_code) {
asm volatile("mov %%ax,%%ds"::"a"(0x10));
//asm volatile("mov %%ax,%%ds"::"a"(0x10));
uint8_t *ip;
uint16_t *stack;
uint32_t *stack32;
@ -84,17 +100,17 @@ void gpf_handler_v86(struct interrupt_frame *frame, unsigned long error_code) {
stack32 = (uint32_t*)stack;
char *vga = (char*)0xb8000 + (160 * 10);
vga[0] = 'I'; vga[2] = 'P'; printWord(frame->eip, &vga[4]); vga += 14;
vga[0] = 'C'; vga[2] = 'S'; printWord(frame->cs, &vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'L'; printDword(frame->eflags, &vga[4]); vga += 14;
vga[0] = 'I'; vga[2] = 'P'; int_printWord(frame->eip, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'C'; vga[2] = 'S'; int_printWord(frame->cs, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'L'; int_printDword(frame->eflags, (uint16_t*)&vga[4]); vga += 14;
vga = (char*)0xb8000 + (160 * 11);
vga[0] = 'S'; vga[2] = 'P'; printWord(frame->esp, &vga[4]); vga += 14;
vga[0] = 'S'; vga[2] = 'S'; printWord(frame->ss, &vga[4]); vga += 14;
vga[0] = 'S'; vga[2] = 'P'; int_printWord(frame->esp, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'S'; vga[2] = 'S'; int_printWord(frame->ss, (uint16_t*)&vga[4]); vga += 14;
vga = (char*)0xb8000 + (160 * 12);
vga[0] = 'E'; vga[2] = 'S'; printWord(frame->es, &vga[4]); vga += 14;
vga[0] = 'D'; vga[2] = 'S'; printWord(frame->ds, &vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'S'; printWord(frame->fs, &vga[4]); vga += 14;
vga[0] = 'G'; vga[2] = 'S'; printWord(frame->gs, &vga[4]); vga += 14;
vga[0] = 'E'; vga[2] = 'S'; int_printWord(frame->es, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'D'; vga[2] = 'S'; int_printWord(frame->ds, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'S'; int_printWord(frame->fs, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'G'; vga[2] = 'S'; int_printWord(frame->gs, (uint16_t*)&vga[4]); vga += 14;
//vga[2]++;
//printDword(frame, &vga[20]);
@ -160,7 +176,7 @@ void gpf_handler_v86(struct interrupt_frame *frame, unsigned long error_code) {
vga[0] = 'I'; vga[2]++; if (vga[2] < '0') vga[2] = '0';
switch (ip[1]) {
case 0x30:
asm("jmp jmp_usermode_test");
asm ("jmp jmp_usermode_test");
for(;;);
case 0x3:
kbd_wait();
@ -172,10 +188,10 @@ void gpf_handler_v86(struct interrupt_frame *frame, unsigned long error_code) {
stack[1] = frame->cs;
stack[2] = (uint16_t) frame->eflags;
//if (v86_if)
// stack[2] |= EFLAG_IF;
//else
// stack[2] &= ~EFLAG_IF;
if (v86_if)
stack[2] |= EFLAG_IF;
else
stack[2] &= ~EFLAG_IF;
frame->cs = ivt[ip[1] * 2 + 1];
frame->eip = ivt[ip[1] * 2];
@ -201,19 +217,19 @@ void gpf_handler_v86(struct interrupt_frame *frame, unsigned long error_code) {
for(;;);
}
}
done:
done:;
vga = (char*)0xb8000 + (160 * 13);
vga[0] = 'I'; vga[2] = 'P'; printWord(frame->eip, &vga[4]); vga += 14;
vga[0] = 'C'; vga[2] = 'S'; printWord(frame->cs, &vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'L'; printDword(frame->eflags, &vga[4]); vga += 14;
vga[0] = 'I'; vga[2] = 'P'; int_printWord(frame->eip, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'C'; vga[2] = 'S'; int_printWord(frame->cs, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'L'; int_printDword(frame->eflags, (uint16_t*)&vga[4]); vga += 14;
vga = (char*)0xb8000 + (160 * 14);
vga[0] = 'S'; vga[2] = 'P'; printWord(frame->esp, &vga[4]); vga += 14;
vga[0] = 'S'; vga[2] = 'S'; printWord(frame->ss, &vga[4]); vga += 14;
vga[0] = 'S'; vga[2] = 'P'; int_printWord(frame->esp, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'S'; vga[2] = 'S'; int_printWord(frame->ss, (uint16_t*)&vga[4]); vga += 14;
vga = (char*)0xb8000 + (160 * 15);
vga[0] = 'E'; vga[2] = 'S'; printWord(frame->es, &vga[4]); vga += 14;
vga[0] = 'D'; vga[2] = 'S'; printWord(frame->ds, &vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'S'; printWord(frame->fs, &vga[4]); vga += 14;
vga[0] = 'G'; vga[2] = 'S'; printWord(frame->gs, &vga[4]); vga += 14;
vga[0] = 'E'; vga[2] = 'S'; int_printWord(frame->es, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'D'; vga[2] = 'S'; int_printWord(frame->ds, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'F'; vga[2] = 'S'; int_printWord(frame->fs, (uint16_t*)&vga[4]); vga += 14;
vga[0] = 'G'; vga[2] = 'S'; int_printWord(frame->gs, (uint16_t*)&vga[4]); vga += 14;
}
extern void timerHandler();
@ -252,8 +268,8 @@ void setup_interrupts() {
set_system_gate(0x20, timerHandler);
set_system_gate(0x21, keyboardHandler);
set_trap_gate(13, gpf_handler_v86);
//set_trap_gate(13, gpfHandler);
//set_trap_gate(13, gpf_handler_v86);
set_trap_gate(13, gpfHandler);
asm volatile("lidt %0": : "m"(IDTR));
picInit();

8
print.c
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@ -1,24 +1,16 @@
#include "print.h"
__attribute((__always_inline__))
__attribute((__no_caller_saved_registers__))
char nibbleToHex(uint8_t n) {
return n > 9 ? (n - 10) + 'A' : n + '0';
}
__attribute((__always_inline__))
__attribute((__no_caller_saved_registers__))
void printByte(uint8_t v, uint16_t *buff) {
*(char *)&buff[0] = nibbleToHex((v >> 4) & 0xF);
*(char *)&buff[1] = nibbleToHex(v & 0xF);
}
__attribute((__always_inline__))
__attribute((__no_caller_saved_registers__))
void printWord(uint16_t v, uint16_t *buff) {
printByte(v >> 8, buff);
printByte(v, &buff[2]);
}
__attribute((__always_inline__))
__attribute((__no_caller_saved_registers__))
void printDword(uint32_t v, uint16_t *buff) {
printWord(v >> 16, buff);
printWord(v, &buff[4]);

3
print.h
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@ -1,9 +1,6 @@
#pragma once
#include <stdint.h>
__attribute((__no_caller_saved_registers__))
void printByte(uint8_t v, uint16_t *buff);
__attribute((__no_caller_saved_registers__))
void printWord(uint16_t v, uint16_t *buff);
__attribute((__no_caller_saved_registers__))
void printDword(uint32_t v, uint16_t *buff);