自己动手实现arm函数栈帧回溯_armv7 栈回溯

作者：小蓝xlanll | 2024-02-28 17:22:15

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armv7 栈回溯

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!

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#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。

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