//online parser:
https://www.bccn.net/run/
程序代码：
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <string.h>
typedef unsigned char uint8_t;
static unsigned short exp_state;
#define EMU_ISR
#ifndef EMU_ISR
static unsigned long *vint;
#else
static unsigned char *vint;
#endif/* EMU_ISR */
#define MAGIC_EXCEPTION 0x9C
#define post_exception(_exp) exp_state = ((_exp << 8) | MAGIC_EXCEPTION);
#define chk_exception() (MAGIC_EXCEPTION == (exp_state & 0xff))
#define clr_exception() (exp_state &= 0xff00)
static inline int vdiv(int num, int den)
{
#define DIV_EXCEPTION 0
if (!den) {
post_exception(DIV_EXCEPTION);
//#define PRINT_ON
#ifdef PRINT_ON
printf("exp_state = 0x%x\n", exp_state);
#endif
return DIV_EXCEPTION;
}
return num / den;
}
#define callback
char* callback log_info(uint8_t errno)
{
static char *log[256] = {
[DIV_EXCEPTION] = "WARNING: arithmetic exception[div zero]"
};
//#define ASM_MARKABLE_INS
#ifdef ASM_MARKABLE_INS
__asm__ ("xor %esi, %esi");
__asm__ ("xor %edi, %edi");
#endif
//len = 28 - 4(ASM_MARKABLE_INS) = 24
return log[errno];
}
void register_vector_tbl(void)
{
vint = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANONYMOUS | MAP_SHARED , 0 , 0);
#ifndef EMU_ISR
vint[DIV_EXCEPTION] = (unsigned long)log_info;
#else/* EMU_ISR */
//emu loading IRQ_0
#define REAL_ISR_OFFSET 1024
#define PREFIX_OP_LEN 5
#define INTEL_NOP 0x90
#ifndef ASM_MARKABLE_INS
#define HRD_LEN_4_LOG_INFO (29 - 4)
#else
#define HRD_LEN_4_LOG_INFO 29
#endif
memcpy(&vint[DIV_EXCEPTION + REAL_ISR_OFFSET], log_info, HRD_LEN_4_LOG_INFO);
/* clr ins pipe by filling Mr.nop */
memset(&vint[PREFIX_OP_LEN], INTEL_NOP, REAL_ISR_OFFSET - PREFIX_OP_LEN);
//prefix opcode jmp dword ptr[rip + 0x3FB]
vint[DIV_EXCEPTION + 0] = 0xe8;
/* 4 quickly location */
vint[DIV_EXCEPTION + 1] = 0xFB;/* thanks 2 NOP(0x90) 0~0x3FB all works well */
vint[DIV_EXCEPTION + 2] = 0x03;/* maybe its a positive bug lalala~~ */
vint[DIV_EXCEPTION + 3] = 0;
vint[DIV_EXCEPTION + 4] = 0;
#endif/* EMU_ISR */
#if !defined(EMU_ISR) && defined(PRINT_ON)
printf("log_info = %p\n", log_info);
printf("vint[%d] = 0x%lx\n", DIV_EXCEPTION, vint[DIV_EXCEPTION]);
#endif
}
void trig_int(uint8_t arg)
{
#ifndef EMU_ISR
#ifdef PRINT_ON
printf("log_info = %p\n", log_info);
printf("vint[%d] = 0x%lx\n", DIV_EXCEPTION, vint[DIV_EXCEPTION]);
#endif
typedef char* (*vect_log)(unsigned char);
puts(((vect_log)vint[DIV_EXCEPTION])(arg));
#else/* EMU_ISR */
if (0 == arg) __asm__ (".byte 0x68, 0x0, 0x0, 0x0, 0x0");
typedef char* (*visr)(void);
puts(((visr)&vint[0])());
#endif/* EMU_ISR */
clr_exception();
#ifdef PRINT_ON
printf("exp_state = 0x%x\n", exp_state);
#endif
}
int main(int argc, char *argv[])
{
uint8_t a = 0, b = 0, c = 0, errno;
int i;
register_vector_tbl();
#define TST_PROCEDURE_CNT 25
for (i = 0; i <= TST_PROCEDURE_CNT; i++) {
printf("[%d]:a = %d, b = %d, c = %d\n", i, a, b, c);
errno= vdiv(a, (b + c));
if (chk_exception()) trig_int(errno);
a = ((uint8_t *)main)[i] % 10;
b = ((uint8_t *)main)[i + 1] % 10;
c = ((uint8_t *)main)[i + 2] % 10;
}
#ifdef ASM_MARKABLE_INS
/* checking irq length */
system("gcc *.c -o v.out");
system("objdump -d v.out");
#endif
munmap(vint, getpagesize());
return 0;
}
over!
