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Register arguments can be passed to v86 code

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This commit is contained in:
Lucia Ceionia
2023-02-02 14:52:26 -06:00
parent 7937de6ef0
commit 750b1edc16
9 changed files with 111 additions and 48 deletions
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17
dosfs/dosfs.c
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@@ -11,19 +11,7 @@
#include "dosfs.h"
#include "tmpstring.c"
#include "../interrupt.h"
struct __attribute((__packed__)) Int13DiskPacket_t {
uint8_t size; // 0x10
uint8_t reserved; // 0x00
uint16_t blocks;
uint32_t transfer_buffer; // 0x2300:0000
uint64_t start_block;
};
extern struct Int13DiskPacket_t v86disk_addr_packet;
extern void enter_v86(uint32_t ss, uint32_t esp, uint32_t cs, uint32_t eip);
extern void v86DiskRead();
#include "../v86defs.h"
// all reading at 0x23000 - be careful!
uint32_t DFS_ReadSector(uint8_t unit, uint8_t *buffer, uint32_t sector, uint32_t count) {
@@ -32,8 +20,9 @@ uint32_t DFS_ReadSector(uint8_t unit, uint8_t *buffer, uint32_t sector, uint32_t
v86disk_addr_packet.transfer_buffer =
(uintptr_t)buffer & 0x000F |
(((uintptr_t)buffer & 0xFFFF0) << 12);
union V86Regs_t regs;
FARPTR v86_entry = i386LinearToFp(v86DiskRead);
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry));
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry), &regs);
return 0;
}
uint32_t DFS_WriteSector(uint8_t unit, uint8_t *buffer, uint32_t sector, uint32_t count) {

16
fault.nasm
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@@ -40,7 +40,7 @@ extern get_key
extern task_ptr
extern _enter_v86_internal_no_task
extern return_prev_task
extern v86GfxMode
extern v86VideoInt
gpf_handler_32:
push eax
mov eax, dword [esp+8] ; EIP
@@ -56,19 +56,23 @@ cmp al, 0x00 ; get key
jne .s1
call get_key
jmp .return_to_offender
.s1: cmp al, 0x10 ; set video mode
.s1: cmp al, 0x10 ; video interrupt
jne .return_to_offender
add esp, 4
add dword [esp+0], 2
; add a new task
call _gpf_create_return_task
; now enter v86 mode
; push args
mov eax, v86GfxMode
; get regs from return stack
mov eax, [esp+12] ; return esp
mov eax, [eax] ; regs
push eax ; regs
mov eax, v86VideoInt
and eax, 0xffff
push eax ; ip
mov eax, v86GfxMode
shr eax, 16
mov eax, v86VideoInt
shr eax, 4
and eax, 0xf000
push eax ; cs
push 0xFF00 ; sp
push 0x8000 ; ss

2
interrupt.c
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@@ -51,7 +51,7 @@ FARPTR i386LinearToFp(void *ptr)
{
unsigned seg, off;
off = (uintptr_t) ptr & 0xffff;
seg = ((uintptr_t) ptr >> 16);
seg = ((uintptr_t) ptr >> 4) & 0xf000;
return MK_FP(seg, off);
}

43
kernel.c
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@@ -5,6 +5,7 @@
#include "interrupt.h"
#include "tss.h"
#include "paging.h"
#include "v86defs.h"
typedef unsigned short word;
@@ -53,22 +54,6 @@ uint32_t get_cr4() {
return reg;
}
struct __attribute((__packed__)) Int13DiskPacket_t {
uint8_t size; // 0x10
uint8_t reserved; // 0x00
uint16_t blocks;
uint32_t transfer_buffer; // 0x2300:0000
uint64_t start_block;
};
extern struct Int13DiskPacket_t v86disk_addr_packet;
extern void enter_v86(uint32_t ss, uint32_t esp, uint32_t cs, uint32_t eip);
extern void v86Test();
extern void v86TransFlag();
extern void v86GfxMode();
extern void v86TextMode();
extern void v86DiskRead();
extern char *jmp_usermode_test();
extern char _edata, _v86code, _ev86code, _bstart, _bend, _loadusercode, _usercode, _eusercode;
@@ -119,8 +104,9 @@ void ensure_v86env() {
void error_environment() {
ensure_v86env();
union V86Regs_t regs;
FARPTR v86_entry = i386LinearToFp(v86TextMode);
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry));
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry), &regs);
printStr("Oh noes!!! System error! ;c Press E for a fun recovery :3", &error_screen[80]);
uint16_t *vga_text = ((uint16_t*)0xB8000);
for (int i = 0; i < 80*50; i++)
@@ -128,7 +114,7 @@ void error_environment() {
uint8_t key;
for (key = get_key(); key != 'e' && key != 'E'; key = get_key());
v86_entry = i386LinearToFp(v86TransFlag);
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry));
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry), &regs);
}
/*
@@ -136,8 +122,8 @@ Real Mode Accessible (First MB)
00000 - 00400 IVT (1kB)
00400 - 01000 Unused (3kB)
01000 - 04000 Free (12kB)
04000 - 07C00 Free (15kB)
07C00 - 08000 Boot (512B)
04000 - 07C00 V86 Code (15kB)
07C00 - 08000 Boot & V86 Code (512B)
08000 - 20000 V86 Code (96kB)
20000 - 30000 Disk Buffer (64kB)
30000 - 80000 Free (320kB)
@@ -158,8 +144,15 @@ Protected Only (1MB+)
*/
void TestV86() {
union V86Regs_t regs;
regs.d.edi = 0x11111111;
regs.d.esi = 0x22222222;
regs.d.ebx = 0x33333333;
regs.d.edx = 0x44444444;
regs.d.ecx = 0x55555555;
regs.d.eax = 0x66666666;
FARPTR v86_entry = i386LinearToFp(v86Test);
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry));
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry), &regs);
}
void TestUser() {
char *vga = jmp_usermode_test();
@@ -168,13 +161,15 @@ void TestUser() {
}
}
void TestDiskRead() {
union V86Regs_t regs;
word *vga_text = (word *)0xb8000 + (80*5);
vga_text += printStr("Setting Text Mode... ", vga_text);
FARPTR v86_entry = i386LinearToFp(v86TextMode);
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry));
regs.w.ax = 3; // text mode
FARPTR v86_entry = i386LinearToFp(v86VideoInt);
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry), &regs);
vga_text += printStr("Done. Starting Disk Read... ", vga_text);
v86_entry = i386LinearToFp(v86DiskRead);
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry));
enter_v86(0x8000, 0xFF00, FP_SEG(v86_entry), FP_OFF(v86_entry), &regs);
vga_text = (word *)0xb8000;
char *diskReadBuf = (char *)0x23000;
for (int i = 0; i < (80*25)/2; i++) {

2
link.ld
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@@ -15,7 +15,7 @@ SECTIONS {
_edata = .;
}
.realmode 0x8000 :
.realmode 0x4000 :
AT ( ADDR(.data) + SIZEOF(.data) )
{ _v86code = .; *(.v86); _ev86code = .; }

13
task.nasm
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@@ -89,7 +89,7 @@ mov ds, ax
mov eax, ecx ; restore return value
iret
; extern void enter_v86(uint32_t ss, uint32_t esp, uint32_t cs, uint32_t eip);
; extern void enter_v86(uint32_t ss, uint32_t esp, uint32_t cs, uint32_t eip, union V86Regs_t *regs);
global enter_v86
global _enter_v86_internal_no_task
enter_v86:
@@ -98,6 +98,17 @@ mov ecx, esp ; return stack
call save_current_task
_enter_v86_internal_no_task:
mov ebp, esp ; save stack pointer
mov eax, dword [ebp+16] ; regs
test eax, eax
jz .no_regs
; load regs: edi, esi, ebx, edx, ecx, eax
mov edi, dword [eax+0]
mov esi, dword [eax+4]
mov ebx, dword [eax+8]
mov edx, dword [eax+12]
mov ecx, dword [eax+16]
mov eax, dword [eax+20]
.no_regs:
push dword [ebp+0] ; ss
push dword [ebp+4] ; esp
pushfd ; eflags

9
usermode.nasm
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@@ -8,7 +8,14 @@ mov dword [0xb800C], 0x0f000f00 | 'd' | 'e' << 16
mov word [0xb8010], 0x0f00 | '!'
mov eax, 0 ; command = 00, get key
int 0x21 ; OS call
mov eax, 0x00030010 ; command = 10, set video mode 3
push 0x00000013 ; eax AH=0,AL=3 set video mode 3
push 0x00000000 ; ecx
push 0x00000000 ; edx
push 0x00000000 ; ebx
push 0x00000000 ; esi
push 0x00000000 ; edi
push esp ; regs
mov eax, 0x10 ; command = 10
int 0x21 ; OS call
mov edi, 0xA0000
xor eax, eax

6
v86.nasm
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@@ -84,6 +84,12 @@ int 0x10
int 0x30
jmp $
global v86VideoInt
v86VideoInt:
int 0x10
int 0x30
jmp $
global v86DiskRead
v86DiskRead:
xor ax, ax ; TODO fix assuming we're in first 64k

51
v86defs.h Normal file
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@@ -0,0 +1,51 @@
#include <stdint.h>
extern void v86Test();
extern void v86TransFlag();
extern void v86GfxMode();
extern void v86TextMode();
extern void v86DiskRead();
extern void v86VideoInt();
union __attribute((__packed__)) V86Regs_t {
struct dword_regs {
uint32_t edi;
uint32_t esi;
uint32_t ebx;
uint32_t edx;
uint32_t ecx;
uint32_t eax;
} d;
struct word_regs {
uint16_t di, _upper_di;
uint16_t si, _upper_si;
uint16_t bx, _upper_bx;
uint16_t dx, _upper_dx;
uint16_t cx, _upper_cx;
uint16_t ax, _upper_ax;
} w;
struct byte_regs {
uint16_t di, _upper_di;
uint16_t si, _upper_si;
uint8_t bl, bh;
uint16_t _upper_bx;
uint8_t dl, dh;
uint16_t _upper_dx;
uint8_t cl, ch;
uint16_t _upper_cx;
uint8_t al, ah;
uint16_t _upper_ax;
} h;
};
extern void enter_v86(uint32_t ss, uint32_t esp, uint32_t cs, uint32_t eip, union V86Regs_t *regs);
struct __attribute((__packed__)) Int13DiskPacket_t {
uint8_t size; // 0x10
uint8_t reserved; // 0x00
uint16_t blocks;
uint32_t transfer_buffer; // 0x2300:0000
uint64_t start_block;
};
extern struct Int13DiskPacket_t v86disk_addr_packet;