How to use the addr2line command in Linux?
You can also use gdb instead of addr2line to examine memory address. Load executable file in gdb and print the name of a symbol which is stored at the address. 16 Examining the Symbol Table.
(gdb) info symbol 0x4005BDC
You need to specify an offset to addr2line, not a virtual address (VA). Presumably if you had address space randomization turned off, you could use a full VA, but in most modern OSes, address spaces are randomized for a new process.
Given the VA 0x4005BDC
by valgrind, find the base address of your process or library in memory. Do this by examining the /proc/<PID>/maps
file while your program is running. The line of interest is the text
segment of your process, which is identifiable by the permissions r-xp
and the name of your program or library.
Let's say that the base VA is 0x0x4005000
. Then you would find the difference between the valgrind supplied VA and the base VA: 0xbdc
. Then, supply that to add2line:
addr2line -e a.out -j .text 0xbdc
And see if that gets you your line number.
That's exactly how you use it. There is a possibility that the address you have does not correspond to something directly in your source code though.
For example:
$ cat t.c#include <stdio.h>int main(){ printf("hello\n"); return 0;}$ gcc -g t.c$ addr2line -e a.out 0x400534/tmp/t.c:3$ addr2line -e a.out 0x400550??:0
0x400534
is the address of main
in my case. 0x400408
is also a valid function address in a.out
, but it's a piece of code generated/imported by GCC, that has no debug info. (In this case, __libc_csu_init
. You can see the layout of your executable with readelf -a your_exe
.)
Other times when addr2line
will fail is if you're including a library that has no debug information.