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Hook bios interrupt 0x08 instead of 0x1c for PIT ticks

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This commit is contained in:
mintsuki 2020-04-25 22:11:55 +02:00
parent 2fd36507a1
commit 09683cc5de
1 changed files with 27 additions and 19 deletions
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46
src/lib/blib.c
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@ -1,6 +1,7 @@
#include <stdint.h>
#include <stddef.h>
#include <stdarg.h>
#include <stdbool.h>
#include <lib/blib.h>
#include <lib/libc.h>
#include <drivers/vga_textmode.h>
@ -23,15 +24,7 @@ void brewind(size_t count) {
}
void *balloc(size_t count) {
void *ret = (void *)bump_allocator_base;
size_t new_base = bump_allocator_base + count;
if (new_base >= BUMP_ALLOCATOR_LIMIT) {
print("PANIC: Old: %x | New: %x\n", (size_t)ret, new_base);
print("PANIC: Allocated: %x\n", count);
panic("Memory allocation failed");
}
bump_allocator_base = new_base;
return ret;
return balloc_aligned(count, 4);
}
// Only power of 2 alignments
@ -49,9 +42,9 @@ void *balloc_aligned(size_t count, size_t alignment) {
return ret;
}
__attribute__((used)) static uint32_t int_1c_ticks_counter;
__attribute__((used)) static uint32_t int_08_ticks_counter;
__attribute__((used)) __attribute__((naked)) static void ivt_timer_isr(void) {
__attribute__((naked)) static void int_08_isr(void) {
asm (
".code16\n\t"
"pushf\n\t"
@ -60,24 +53,28 @@ __attribute__((used)) __attribute__((naked)) static void ivt_timer_isr(void) {
"inc dword ptr ds:[ebx]\n\t"
"pop bx\n\t"
"popf\n\t"
"int 0x40\n\t" // call callback
"iret\n\t"
".code32\n\t"
"1: .long int_1c_ticks_counter\n\t"
"1: .long int_08_ticks_counter\n\t"
);
}
uint32_t *ivt = 0; // this variable is not static else gcc will optimise the
// 0 ptr to a ud2
static void hook_int_08(void) {
ivt[0x40] = ivt[0x08]; // int 0x40 is callback interrupt
ivt[0x08] = rm_seg(int_08_isr) << 16 | rm_off(int_08_isr);
}
// This is a dirty hack but we need to execute this full function in real mode
__attribute__((naked)) int pit_sleep_and_quit_on_keypress(uint32_t ticks) {
__attribute__((naked)) int _pit_sleep_and_quit_on_keypress(uint32_t ticks) {
asm (
// pit_ticks in edx
"mov edx, dword ptr ss:[esp+4]\n\t"
"lea ecx, int_1c_ticks_counter\n\t"
// Make sure the ISR for int 0x1c is hooked
"lea eax, ivt_timer_isr\n\t"
"mov word ptr ds:[0x1c * 4], ax\n\t"
"mov word ptr ds:[0x1c * 4 + 2], 0\n\t"
"lea ecx, int_08_ticks_counter\n\t"
"mov dword ptr ds:[ecx], 0\n\t"
@ -158,6 +155,17 @@ __attribute__((naked)) int pit_sleep_and_quit_on_keypress(uint32_t ticks) {
);
}
static bool int_08_hooked = false;
int pit_sleep_and_quit_on_keypress(uint32_t ticks) {
if (!int_08_hooked) {
hook_int_08();
int_08_hooked = true;
}
return _pit_sleep_and_quit_on_keypress(ticks);
}
uint64_t strtoui(const char *s) {
uint64_t n = 0;
while (*s)