Summary of Linux kernel debugging methods BackTrace

BackTrace

"Use" user-state or kernel-state program to backtrack stack information when exiting abnormally

"principle" by analyzing the current stack, backtracking the upper function's frame address in the current stack until the top-level function. A frame address is a memory space in which a local variable, a function return address, and a register value exist in the stack. Because different processor stacks are implemented differently (up and down), the implementation of this feature is the compiler's built-in __buildin_frame_address and __buildin_return_address functions. If the compiler does not support this function, you can implement it yourself.

"Interface description" specific instructions can refer to man backtrace Help documentation

Execinfo.h

int BackTrace (void **buffer, int size)
The BackTrace function obtains a backtrace for the current thread, as a list of pointers, and places the information into buffer.

char * * Backtrace_symbols (void *const *buffer, int size)

The Backtrace_symbols function translates the information obtained from the BackTrace function to an array of strings. The argument buffer should is a pointer to an array of addresses obtained via the BackTrace function, and siz E is the number of entries in that array (the return value of BackTrace).

void backtrace_symbols_fd (void *const *buffer, int size, int fd)

Instance

#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <execinfo.h>

#include <fcntl.h>

#include <string.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/stat.h>

#define Print_debug

#define MAX_BACKTRACE_LEVEL 10

#define BACKTRACE_LOG_NAME "Backtrace.log"

static void Show_reason (int sig, siginfo_t *info, void *secret) {

void *array[max_backtrace_level];

size_t size;

#ifdef Print_debug

Char **strings;

size_t i;

Size = BackTrace (array, max_backtrace_level);

strings = Backtrace_symbols (array, size);

printf ("Obtain%ZD stack frames.\n", size);

for (i = 0; i < size; i++)

printf ("%s\n", Strings[i]);

Free (strings);

#else

int fd = open (Backstrace_log_name, O_creat | O_WRONLY);

Size = BackTrace (array, max_backtrace_level);

BACKTRACE_SYMBOLS_FD (array, size, FD);

Close (FD);

#endif

Exit (0);

}

void Die () {

Char *str1;

Char *str2;

Char *STR3;

char *STR4 = NULL;

strcpy (STR4, "AB");

}

void Let_it_die () {

Die ();

}

int main (int argc, char **argv) {

struct Sigaction Act;

Act.sa_sigaction = Show_reason;

Sigemptyset (&act.sa_mask);

Act.sa_flags = Sa_restart | Sa_siginfo;

Sigaction (SIGSEGV, &act, NULL);

Sigaction (SIGUSR1, &act, NULL);

Sigaction (SIGFPE, &act, NULL);

Sigaction (Sigill, &act, NULL);

Sigaction (Sigbus, &act, NULL);

Sigaction (SIGABRT, &act, NULL);

Sigaction (Sigsys, &act, NULL);

Let_it_die ();

return 0;

}

Debugging

1) compiling

[Email protected]:~/test$ gcc backtrace_test.c-o backtrace_test-g–rdynamic

(Note:-rdynamic, this option is passed to linker, linker will place the symbol in the. Dydym table so backtrace_symbols can get the symbol corresponding to the address.) So even if you use the-G to compile the program, if you do not use-rdynamic, Backtrace_symbols can not find the address corresponding to the symbol. This is a flaw in the BackTrace series function)

2) Run

[Email protected]:~/test$./backtrace_test

Obtain 7 stack frames.

./backtrace_test () [0x40096e]

/lib/x86_64-linux-gnu/libc.so.6 (+0x364a0) [0x7f2ff171c4a0]

./backtrace_test (die+0x18) [0X400A03]

./backtrace_test (LET_IT_DIE+0XE) [0x400a1d]

./backtrace_test (Main+0xf6) [0X400B15]

/lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xed) [0x7f2ff170776d]

./backtrace_test () [0x400889]

Summary of Linux kernel debugging methods BackTrace