[Linux] [C / C ++] How to get the return address value of a function and the function name of the caller

TL;DR

I want to debug a function called from various places, so I want to get the function name of the caller.

It would be nice to use __builtin_return_address (0) and dladdr.

Implementation sample

test.c(Get the caller's function name and return address)

#include <stdio.h>
#define __USE_GNU
#include <dlfcn.h>

void hoge() {
    Dl_info info;
    dladdr(__builtin_return_address(0), &info);
    printf("[%s] parent func name => %p [%s]\n",
           __func__,
           __builtin_return_address(0),
           info.dli_sname);
}

void foo() {
    hoge();

    Dl_info info;
    dladdr(__builtin_return_address(0), &info);
    printf("[%s] parent func name => %p [%s]\n",
           __func__,
           __builtin_return_address(0),
           info.dli_sname);
}

int main(int argc, char const* argv[])
{
    hoge();

    foo();

    return 0;
}

The result of the execution is as follows. You can get the symbol name from dladdr.

$ gcc test.c -ldl -rdynamic
$ ./a.out
[hoge] parent func name => 0x4008ee [main]
[hoge] parent func name => 0x40089e [foo]
[foo] parent func name => 0x4008f8 [main]

However, this method is limited and you have to build with -rdynamic. (-rdynamic => Add all symbols to the dynamic symbol table)

If the symbol does not exist in the dynamic symbol table, the name cannot be obtained by dladdr.

Execution result

$ gcc test.c -ldl
$ ./a.out
[hoge] parent func name => 0x4006de [(null)]
[hoge] parent func name => 0x40068e [(null)]
[foo] parent func name => 0x4006e8 [(null)]

Since the return address is known by __builtin_return_address (0), it can be determined by using, for example, ʻobjdump`.

$ objdump -d ./a.out | view -
000000000040067c <foo>: #Caller
  40067c:	55                   	push   %rbp
  40067d:	48 89 e5             	mov    %rsp,%rbp
  400680:	48 83 ec 20          	sub    $0x20,%rsp
  400684:	b8 00 00 00 00       	mov    $0x0,%eax
  400689:	e8 af ff ff ff       	callq  40063d <hoge>
  40068e:	48 8b 45 08          	mov    0x8(%rbp),%rax   #Return here when exiting hoge
  400692:	48 8d 55 e0          	lea    -0x20(%rbp),%rdx
  400696:	48 89 d6             	mov    %rdx,%rsi
  400699:	48 89 c7             	mov    %rax,%rdi
  40069c:	e8 7f fe ff ff       	callq  400520 <dladdr@plt>
  4006a1:	48 8b 55 f0          	mov    -0x10(%rbp),%rdx
  4006a5:	48 8b 45 08          	mov    0x8(%rbp),%rax
  4006a9:	48 89 d1             	mov    %rdx,%rcx
  4006ac:	48 89 c2             	mov    %rax,%rdx
  4006af:	be 9f 07 40 00       	mov    $0x40079f,%esi
  4006b4:	bf 78 07 40 00       	mov    $0x400778,%edi
  4006b9:	b8 00 00 00 00       	mov    $0x0,%eax
  4006be:	e8 4d fe ff ff       	callq  400510 <printf@plt>
  4006c3:	c9                   	leaveq 
  4006c4:	c3                   	retq   
~Omission~
00000000004006c5 <main>: #Caller
  4006c5:	55                   	push   %rbp
  4006c6:	48 89 e5             	mov    %rsp,%rbp
  4006c9:	48 83 ec 10          	sub    $0x10,%rsp
  4006cd:	89 7d fc             	mov    %edi,-0x4(%rbp)
  4006d0:	48 89 75 f0          	mov    %rsi,-0x10(%rbp)
  4006d4:	b8 00 00 00 00       	mov    $0x0,%eax
  4006d9:	e8 5f ff ff ff       	callq  40063d <hoge>
  4006de:	b8 00 00 00 00       	mov    $0x0,%eax     #Return here when exiting hoge
  4006e3:	e8 94 ff ff ff       	callq  40067c <foo>
  4006e8:	b8 00 00 00 00       	mov    $0x0,%eax     #Return here when exiting foo
  4006ed:	c9                   	leaveq 
  4006ee:	c3                   	retq   
  4006ef:	90                   	nop

Relation

Debugging seems to improve when combined with the hook in LD_PRELOAD that I investigated earlier.

Replace printf later with LD_PRELOAD --Qiita

reference

How to get the string of the function name in C-Diary of Taisho (miettal) Function caller in linux kernel - Stack Overflow How to get function's name from function's pointer in C? - Stack Overflow Return Address - Using the GNU Compiler Collection (GCC) Function tracer with GCC compile options-diary of torutk About __builtin_return_address --syohex ’s diary