转自：http://blog.csdn.net/dragon101788/article/details/18668505
内核版本：2.6.14
glibc版本：2.3.6
CPU平台：arm
glic中其实有这些函数,当时用的uclib版本较低,没有这些函数,但又需要,只能自己实现了(较高的版本应该有这些函数,换版本很麻烦),而且可以加深自己对这方面的理解.原理性的东西就不深入讲解了,直接上例子!
- #include <stdio.h>
- #include <stdlib.h>
- #include <signal.h>
- #include <assert.h>
- #include <ucontext.h>
- void A(int a);
- void B(int b);
- void C(int c);
- void DebugBacktrace(unsigned int sn , siginfo_t *si , void *ptr);
- typedef struct
- {
- const char *dli_fname; /* File name of defining object. */
- void *dli_fbase; /* Load address of that object. */
- const char *dli_sname; /* Name of nearest symbol.比如函数名*/
- void *dli_saddr; /* Exact value of nearest symbol.比如函数的起始地址*/
- } Dl_info;
- struct ucontext_ce123 {
- unsigned long uc_flags;
- struct ucontext *uc_link;
- stack_t uc_stack;
- struct sigcontext uc_mcontext;
- sigset_t uc_sigmask; /* mask last for extensibility */
- }ucontext_ce123_;
- struct sigframe_ce123 {
- struct sigcontext sc;//保存一组寄存器上下文
- unsigned long extramask[1];
- unsigned long retcode;//保存返回地址
- //struct aux_sigframe aux __attribute__((aligned(8)));
- }sigframe_ce123;
- int backtrace_ce123 (void **array, int size);
- char ** backtrace_symbols_ce123 (void *const *array, int size);
- int backtrace_ce123 (void **array, int size)
- {
- if (size <= 0)
- return 0;
- int *fp = 0, *next_fp = 0;
- int cnt = 0;
- int ret = 0;
- __asm__(
- "mov %0, fp\n"
- : "=r"(fp)
- );
- array[cnt++] = (void *)(*(fp-1));
- next_fp = (int *)(*(fp-3));
- while((cnt <= size) && (next_fp != 0))
- {
- array[cnt++] = (void *)*(next_fp - 1);
- next_fp = (int *)(*(next_fp-3));
- }
- ret = ((cnt <= size)?cnt:size);
- printf("Backstrace (%d deep)\n", ret);
- return ret;
- }
- char ** backtrace_symbols_ce123 (void *const *array, int size)
- {
- # define WORD_WIDTH 8
- Dl_info info[size];
- int status[size];
- int cnt;
- size_t total = 0;
- char **result;
- /* Fill in the information we can get from `dladdr'. */
- for (cnt = 0; cnt < size; ++cnt)
- {
- status[cnt] = _dl_addr (array[cnt], &info[cnt]);
- if (status[cnt] && info[cnt].dli_fname && info[cnt].dli_fname[0] != '\0')
- /* We have some info, compute the length of the string which will be
- "<file-name>(<sym-name>) [+offset]. */
- total += (strlen (info[cnt].dli_fname ?: "")
- + (info[cnt].dli_sname ? strlen (info[cnt].dli_sname) + 3 + WORD_WIDTH + 3 : 1)
- + WORD_WIDTH + 5);
- else
- total += 5 + WORD_WIDTH;
- }
- /* Allocate memory for the result. */
- result = (char **) malloc (size * sizeof (char *) + total);
- if (result != NULL)
- {
- char *last = (char *) (result + size);
- for (cnt = 0; cnt < size; ++cnt)
- {
- result[cnt] = last;
- if (status[cnt] && info[cnt].dli_fname && info[cnt].dli_fname[0] != '\0')
- {
- char buf[20];
- if (array[cnt] >= (void *) info[cnt].dli_saddr)
- sprintf (buf, "+%#lx", \
- (unsigned long)(array[cnt] - info[cnt].dli_saddr));
- else
- sprintf (buf, "-%#lx", \
- (unsigned long)(info[cnt].dli_saddr - array[cnt]));
- last += 1 + sprintf (last, "%s%s%s%s%s[%p]",
- info[cnt].dli_fname ?: "",
- info[cnt].dli_sname ? "(" : "",
- info[cnt].dli_sname ?: "",
- info[cnt].dli_sname ? buf : "",
- info[cnt].dli_sname ? ") " : " ",
- array[cnt]);
- }
- else
- last += 1 + sprintf (last, "[%p]", array[cnt]);
- }
- assert (last <= (char *) result + size * sizeof (char *) + total);
- }
- return result;
- }
- void A(int a)
- {
- printf("%d: A call B\n", a);
- B(2);
- }
- void B(int b)
- {
- printf("%d: B call C\n", b);
- C(3); /* 这个函数调用将导致段错误*/
- }
- void C(int c)
- {
- char *p = (char *)c;
- *p = 'A'; /* 如果参数c不是一个可用的地址值，则这条语句导致段错误 */
- printf("%d: function C\n", c);
- }
- /* SIGSEGV信号的处理函数，回溯栈，打印函数的调用关系*/
- void DebugBacktrace(unsigned int sn , siginfo_t *si , void *ptr)
- {
- /*int *ip = 0;
- __asm__(
- "mov %0, ip\n"
- : "=r"(ip)
- );
- printf("sp = 0x%x\n", ip);
- struct sigframe_ce123 * sigframe = (struct sigframe_ce123 * )ip;*/
- if(NULL != ptr)
- {
- printf("\n\nunhandled page fault (%d) at: 0x%08x\n", si->si_signo,si->si_addr);
- struct ucontext_ce123 *ucontext = (struct ucontext_ce123 *)ptr;
- int pc = ucontext->uc_mcontext.arm_pc;
- void *pc_array[1];
- pc_array[0] = pc;
- char **pc_name = backtrace_symbols_ce123(pc_array, 1);
- printf("%d: %s\n", 0, *pc_name);
- #define SIZE 100
- void *array[SIZE];
- int size, i;
- char **strings;
- size = backtrace_ce123(array, SIZE);
- strings = backtrace_symbols_ce123(array, size);
- for(i=0;i<size;i++)
- printf("%d: %s\n", i+1, strings[i]);
- free(strings);
- }
- else
- printf("error!\n");
- exit(-1);
- }
- int main(int argc, char **argv)
- {
- char a;
- struct sigaction s;
- s.sa_flags = SA_SIGINFO;
- s.sa_sigaction = (void *)DebugBacktrace;
- sigaction (SIGSEGV,&s,NULL);
- A(1);
- C(&a);
- return 0;
- }
代码的下载地址：http://download.csdn.net/detail/ce123/5063160
编译命令：arm-linux-gcc -rdynamic -o segfault segfault.c
_dl_addr链接不通过时，使用-ldl。如果没有该函数，可用dladdr函数代替。
【作者】
张昺华
【新浪微博】 张昺华--sky
【twitter】 @sky2030_
【facebook】 张昺华 zhangbinghua
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利.
