Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction

From: Wangnan (F)
Date: Wed Nov 18 2015 - 03:11:40 EST

On 2015/11/18 15:20, Wangnan (F) wrote:
Hi all,

When analysising Jiri's patchset [1] I found a dwarf unwind problem.
On x86 platform, when sample is at a 'callq' instruction, dwarf based
stack unwind always fail.

I compile a small C source file with debug information, turn off
frame pointer and disable optimization:

$ gcc -g -O0 -fomit-frame-pointer ./test_dwarf_unwind.c -o ./test_dwarf_unwind

For whom want to test it: here is the test code I used.

#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>

static volatile int x = 0;

int funcc(void)
struct timeval tv1, tv2;
unsigned long us1, us2;

gettimeofday(&tv1, NULL);

us1 = tv1.tv_sec * 1000000 + tv1.tv_usec;

while(1) {
x = x + 100;
gettimeofday(&tv2, NULL);
us2 = tv2.tv_sec * 1000000 + tv2.tv_usec;
if (us2 - us1 >= 3000000)
return x;
int funcb(void) { return funcc();}
int funca(void) { return funcb();}
int main() { funca(); return 0;}

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at