概要
ARM平台调试段错误很麻烦,主要原因有一下几点:
- gdb不容易跑,嵌入式系统一般内存不够大
- valgrind也需要占用很大的内存
- 有的平台工具链不支持backtrace
有一种办法是捕获发生段错误时的信号,打印出发生段错误时的各种寄存器的值,其中非常关键的一个寄存器就是pc寄存器的值,通过objdump反汇编出源码之后,可以快速定位到发生错误的代码行,代码如下:
// Last Update:2019-03-15 11:49:54
/**
* @file segfault.c
* @brief
* @author felix
* @version 0.1.00
* @date 2019-03-15
*/
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
static void catch_segfault ( int signal, siginfo_t *_si, void *ctx )
{
unsigned long int *addr = NULL;
char * registers[] =
{
"trap_no",
"error_code",
"oldmask",
"arm_r0",
"arm_r1",
"arm_r2",
"arm_r3",
"arm_r4",
"arm_r5",
"arm_r6",
"arm_r7",
"arm_r8",
"arm_r9",
"arm_r10",
"arm_fp",
"arm_ip",
"arm_sp",
"arm_lr",
"arm_pc",
"arm_cpsr",
"fault_address",
};
int i = 0;
if ( signal == SIGSEGV ) {
printf("signal : SIGSEGV\n");
if ( _si ) {
printf("signo : %d\n", _si->si_signo );
printf("errno : %d\n", _si->si_errno );
printf("addr : %p\n", _si->si_addr );
printf("pid : %p\n", _si->si_pid );
} else {
printf("_si is NULL\n");
}
if ( ctx ) {
addr = ( unsigned long int *)(ctx + sizeof(unsigned long ) + sizeof( void *) + sizeof( stack_t ));
for ( i=0; i<sizeof(registers)/sizeof(registers[0]); i++ ) {
printf("%s : 0x%lx\n", registers[i], *addr++ );
}
} else {
printf("ctx is NULL\n");
}
}
exit(1);
}
static void __attribute__ ((constructor)) install_handler (void)
{
struct sigaction sa;
stack_t ss;
void *stack_mem = malloc (2 * SIGSTKSZ);
sa.sa_handler = (void *) catch_segfault;
sa.sa_flags = SA_SIGINFO;
sigemptyset (&sa.sa_mask);
if (stack_mem != NULL) {
ss.ss_sp = stack_mem;
ss.ss_flags = 0;
ss.ss_size = 2 * SIGSTKSZ;
if (sigaltstack (&ss, NULL) == 0)
sa.sa_flags |= SA_ONSTACK;
}
sigaction (SIGSEGV, &sa, NULL);
}
代码加入自己工程
- 只需要将此代码保存一个.c,和自己的工程一起编译即可
说明
- 代码已经上传到本人的github,地址:https://github.com/felix-001/segment-fault/blob/master/segfault.c