How to use backtrace() with addr2line to get line numbers of the call stack?

Question

I'm trying to use backtrace() in conjunction with addr2line to obtain line numbers for a call stack.

Here's the content of my main.cpp:

#include <execinfo.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

void print_stack_trace() {
  void *array[10];
  size_t size;
  char **strings;
  size_t i;

  // Get the current call stack
  size = backtrace(array, 20);

  // Convert it into an array of strings
  strings = backtrace_symbols(array, size);

  if (strings == NULL) {
    perror("backtrace_symbols");
    exit(EXIT_FAILURE);
  }

  // Print all the stack trace symbols
  for (i = 0; i < size; i++) {
    printf("%s\n", strings[i]);
  }

  free(strings);
}

void dummy_function() {
  // Generate a stack trace
  print_stack_trace();
}

int main(void) {
  // Call a function and then print the stack trace within that function
  dummy_function();
  return 0;
}

I compiled the code with the following command:

g++ -rdynamic -g3 main.cpp -o main.out

When I run the executable:

./main.out

The output is:

./main.out(_Z17print_stack_tracev+0x2c) [0x556c59bed235]
./main.out(_Z14dummy_functionv+0xd) [0x556c59bed2da]
./main.out(main+0xd) [0x556c59bed2ea]
/lib/x86_64-linux-gnu/libc.so.6(+0x29d90) [0x7f9128c7bd90]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80) [0x7f9128c7be40]
./main.out(_start+0x25) [0x556c59bed145]

According to the backtrace_symbols() man page, the addresses in the brackets (e.g., 0x556c59bed2da) are return addresses. I've compiled with the -g option and used addr2line as follows:

addr2line -f -e ./main.out 0x556c59bed2da

But the output is:

??
??:0

I checked the function addresses with objdump:

objdump -S -l -d ./main.out

The addresses seem to start with 0000, like so:

0000000000001209 <_Z17print_stack_tracev>:
00000000000012cd <_Z14dummy_functionv>:

These do not match the backtrace_symbols() output (0x556c59bed2da).

How can I use addr2line to determine the line numbers of the call stack correctly?

Answer 1

Find the base address of your process in memory by examining the /proc/<PID>/maps while your program is running. This is a line that has the name of your program and the permissions r-xp (executable segment).

Let's say the base address is 0x556c59bec000. Then the address inside _Z14dummy_functionv in the .text map table is 0x556c59bed2da minus 0x556c59bec000 is 12da. Pass it to addr2line.