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Rewrite pit_sleep_and_quit_on_keypress() to be fully in real mode to avoid issues with switching back and forth

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This commit is contained in:
mintsuki 2020-04-25 20:33:26 +02:00
parent 8ef1e28e9d
commit 2fd36507a1
9 changed files with 112 additions and 188 deletions
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4
Makefile
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@ -17,7 +17,7 @@ echfs-test: all
echfs-utils -g -p1 test.img import test/test.elf boot/test.elf
echfs-utils -g -p1 test.img import test/qloader2.cfg qloader2.cfg
./qloader2-install src/qloader2.bin test.img 2048
qemu-system-x86_64 -hda test.img -monitor stdio
qemu-system-x86_64 -hda test.img -debugcon stdio
ext2-test: all
$(MAKE) -C test
@ -38,4 +38,4 @@ ext2-test: all
sudo losetup -d `cat loopback_dev`
rm -rf test_image loopback_dev
./qloader2-install src/qloader2.bin test.img 2048
qemu-system-x86_64 -hda test.img -monitor stdio
qemu-system-x86_64 -hda test.img -debugcon stdio

BIN
qloader2.bin
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124
src/lib/blib.c
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@ -5,7 +5,6 @@
#include <lib/libc.h>
#include <drivers/vga_textmode.h>
#include <lib/real.h>
#include <sys/interrupt.h>
#include <lib/cio.h>
void panic(const char *str) {
@ -50,26 +49,113 @@ void *balloc_aligned(size_t count, size_t alignment) {
return ret;
}
void pit_sleep(uint64_t pit_ticks) {
uint64_t target = global_pit_tick + pit_ticks;
while (global_pit_tick < target) {
asm volatile ("hlt");
}
__attribute__((used)) static uint32_t int_1c_ticks_counter;
__attribute__((used)) __attribute__((naked)) static void ivt_timer_isr(void) {
asm (
".code16\n\t"
"pushf\n\t"
"push bx\n\t"
"mov ebx, dword ptr ds:[1f]\n\t"
"inc dword ptr ds:[ebx]\n\t"
"pop bx\n\t"
"popf\n\t"
"iret\n\t"
".code32\n\t"
"1: .long int_1c_ticks_counter\n\t"
);
}
int pit_sleep_and_quit_on_keypress(uint64_t pit_ticks) {
uint64_t target = global_pit_tick + pit_ticks;
while (global_pit_tick < target) {
struct rm_regs r = {0};
r.eax = 0x0100;
rm_int(0x16, &r, &r);
if (!(r.eflags & EFLAGS_ZF)) {
r.eax = 0x0000;
rm_int(0x16, &r, &r);
return 1;
}
}
return 0;
// 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) {
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"
"mov dword ptr ds:[ecx], 0\n\t"
// Save non-scratch GPRs
"push ebx\n\t"
"push esi\n\t"
"push edi\n\t"
"push ebp\n\t"
// Jump to real mode
"jmp 0x08:1f\n\t"
"1: .code16\n\t"
"mov ax, 0x10\n\t"
"mov ds, ax\n\t"
"mov es, ax\n\t"
"mov fs, ax\n\t"
"mov gs, ax\n\t"
"mov ss, ax\n\t"
"mov eax, cr0\n\t"
"and al, 0xfe\n\t"
"mov cr0, eax\n\t"
"jmp 0:2f\n\t"
"2:\n\t"
"mov ax, 0\n\t"
"mov ds, ax\n\t"
"mov es, ax\n\t"
"mov fs, ax\n\t"
"mov gs, ax\n\t"
"mov ss, ax\n\t"
"sti\n\t"
"10:\n\t"
"cmp dword ptr ds:[ecx], edx\n\t"
"je 30f\n\t" // out on timeout
"mov ah, 0x01\n\t"
"xor al, al\n\t"
"int 0x16\n\t"
"jz 10b\n\t" // loop
// on keypress
"xor ax, ax\n\t"
"int 0x16\n\t"
"mov eax, 1\n\t"
"jmp 20f\n\t" // out
"30:\n\t" // out on timeout
"xor eax, eax\n\t"
"20:\n\t"
"cli\n\t"
// Jump back to pmode
"mov ebx, cr0\n\t"
"or bl, 1\n\t"
"mov cr0, ebx\n\t"
"jmp 0x18:4f\n\t"
"4: .code32\n\t"
"mov bx, 0x20\n\t"
"mov ds, bx\n\t"
"mov es, bx\n\t"
"mov fs, bx\n\t"
"mov gs, bx\n\t"
"mov ss, bx\n\t"
// Restore non-scratch GPRs
"pop ebp\n\t"
"pop edi\n\t"
"pop esi\n\t"
"pop ebx\n\t"
// Exit
"ret\n\t"
);
}
uint64_t strtoui(const char *s) {

2
src/lib/blib.h
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@ -7,7 +7,7 @@
void panic(const char *str);
void pit_sleep(uint64_t pit_ticks);
int pit_sleep_and_quit_on_keypress(uint64_t pit_ticks);
int pit_sleep_and_quit_on_keypress(uint32_t pit_ticks);
void brewind(size_t count);
void *balloc(size_t count);

30
src/lib/real.c
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@ -1,3 +1,4 @@
#include <stdint.h>
#include <lib/real.h>
__attribute__((naked))
@ -23,19 +24,6 @@ void rm_int(
"push esi\n\t"
"push edi\n\t"
"push ebp\n\t"
"pushf\n\t"
"cli\n\t"
"mov dx, 0x21\n\t"
"mov al, byte ptr ds:[rm_pic0_mask]\n\t"
"out dx, al\n\t"
"mov dx, 0xa1\n\t"
"mov al, byte ptr ds:[rm_pic1_mask]\n\t"
"out dx, al\n\t"
"sidt [8f]\n\t"
"lidt [9f]\n\t"
// Jump to real mode
"jmp 0x08:1f\n\t"
@ -106,17 +94,7 @@ void rm_int(
"mov gs, ax\n\t"
"mov ss, ax\n\t"
"mov dx, 0x21\n\t"
"mov al, byte ptr ds:[pm_pic0_mask]\n\t"
"out dx, al\n\t"
"mov dx, 0xa1\n\t"
"mov al, byte ptr ds:[pm_pic1_mask]\n\t"
"out dx, al\n\t"
"lidt [8f]\n\t"
// Restore non-scratch GPRs
"popf\n\t"
"pop ebp\n\t"
"pop edi\n\t"
"pop esi\n\t"
@ -131,11 +109,5 @@ void rm_int(
"6: .long 0\n\t"
// in_regs
"7: .long 0\n\t"
// pmode IDT
"8: .short 0\n\t"
" .long 0\n\t"
// rmode IDT
"9: .short 0x3ff\n\t"
" .long 0\n\t"
);
}

7
src/main.c
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@ -12,7 +12,6 @@ asm (
#include <lib/part.h>
#include <lib/config.h>
#include <fs/file.h>
#include <sys/interrupt.h>
#include <lib/elf.h>
#include <protos/stivale.h>
#include <protos/linux.h>
@ -93,8 +92,6 @@ void main(int boot_drive) {
// Initial prompt.
init_vga_textmode();
init_idt();
print("qloader2\n\n");
print("Boot drive: %x\n", boot_drive);
@ -166,7 +163,9 @@ got_entry:
panic("KERNEL_PROTO not specified");
}
fopen(&f, drive, part, path);
if (fopen(&f, drive, part, path)) {
panic("Could not open kernel file");
}
if (!strcmp(proto, "stivale")) {
stivale_load(&f, cmdline);

13
src/protos/linux.c
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@ -103,15 +103,6 @@ void linux_load(struct file_handle *fd, char *cmdline) {
"cli\n\t"
"cld\n\t"
"mov dx, 0x21\n\t"
"mov al, byte ptr ds:[rm_pic0_mask]\n\t"
"out dx, al\n\t"
"mov dx, 0xa1\n\t"
"mov al, byte ptr ds:[rm_pic1_mask]\n\t"
"out dx, al\n\t"
"lidt [3f]\n\t"
"jmp 0x08:1f\n\t"
"1: .code16\n\t"
"mov ax, 0x10\n\t"
@ -136,10 +127,6 @@ void linux_load(struct file_handle *fd, char *cmdline) {
"push cx\n\t"
"push 0\n\t"
"retf\n\t"
// rmode IDT
"3: .short 0x3ff\n\t"
" .long 0\n\t"
:
: "b" (real_mode_code_seg), "c" (kernel_entry_seg)
);

102
src/sys/interrupt.c
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@ -1,102 +0,0 @@
#include <stddef.h>
#include <stdint.h>
#include <sys/interrupt.h>
#include <lib/cio.h>
#include <lib/blib.h>
#include <lib/real.h>
__attribute__((interrupt)) static void unhandled_int(void *r) {
(void)r;
panic("Unhandled interrupt");
}
volatile uint64_t global_pit_tick = 0;
__attribute__((interrupt)) static void pit_irq(void *r) {
(void)r;
global_pit_tick++;
port_out_b(0x20, 0x20);
}
__attribute__((naked)) static void ivt_timer_isr(void) {
asm (
".code16\n\t"
"pushf\n\t"
"push bx\n\t"
"mov ebx, dword ptr ds:[1f]\n\t"
"inc dword ptr ds:[ebx]\n\t"
"pop bx\n\t"
"popf\n\t"
"iret\n\t"
".code32\n\t"
"1: .long global_pit_tick\n\t"
);
}
uint8_t rm_pic0_mask = 0xff;
uint8_t rm_pic1_mask = 0xff;
uint8_t pm_pic0_mask = 0xff;
uint8_t pm_pic1_mask = 0xff;
struct idt_entry_t {
uint16_t offset_lo;
uint16_t selector;
uint8_t unused;
uint8_t type_attr;
uint16_t offset_hi;
} __attribute__((packed));
struct idt_ptr_t {
uint16_t size;
uint32_t address;
} __attribute__((packed));
#define IDT_MAX_ENTRIES 16
static struct idt_entry_t idt[IDT_MAX_ENTRIES];
void init_idt(void) {
rm_pic0_mask = port_in_b(0x21);
rm_pic1_mask = port_in_b(0xa1);
for (int i = 0; i < IDT_MAX_ENTRIES; i++) {
register_interrupt_handler(i, unhandled_int, 0x8e);
}
register_interrupt_handler(0x08, pit_irq, 0x8e);
ivt_register_handler(0x1c, ivt_timer_isr);
struct idt_ptr_t idt_ptr = {
sizeof(idt) - 1,
(uint32_t)idt
};
asm volatile (
"lidt %0"
:
: "m" (idt_ptr)
);
pm_pic0_mask = 0xfe;
pm_pic1_mask = 0xff;
port_out_b(0x21, pm_pic0_mask);
port_out_b(0xa1, pm_pic1_mask);
asm volatile ("sti");
}
void register_interrupt_handler(size_t vec, void *handler, uint8_t type) {
uint32_t p = (uint32_t)handler;
idt[vec].offset_lo = (uint16_t)p;
idt[vec].selector = 0x18;
idt[vec].unused = 0;
idt[vec].type_attr = type;
idt[vec].offset_hi = (uint16_t)(p >> 16);
}
void ivt_register_handler(int vect, void *isr) {
volatile uint32_t *ivt = (volatile void *)0;
ivt[vect] = rm_seg(isr) << 16 | rm_off(isr);
}

18
src/sys/interrupt.h
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@ -1,18 +0,0 @@
#ifndef __SYS__INTERRUPT_H__
#define __SYS__INTERRUPT_H__
#include <stdint.h>
#include <stddef.h>
extern volatile uint64_t global_pit_tick;
extern uint8_t rm_pic0_mask;
extern uint8_t rm_pic1_mask;
extern uint8_t pm_pic0_mask;
extern uint8_t pm_pic1_mask;
void init_idt(void);
void register_interrupt_handler(size_t, void *, uint8_t);
void ivt_register_handler(int vect, void *isr);
#endif