perf annotate: Fix jump parsing for C++ code.

perf annotate: Fix jump parsing for C++ code.

commit 1f0e6edcd968ff19211245f7da6039e983aa51e5 upstream.

Considering the following testcase:

  int
  foo(int a, int b)
  {
     for (unsigned i = 0; i < 1000000000; i++)
       a += b;
     return a;
  }

  int main()
  {
     foo (3, 4);
     return 0;
  }

'perf annotate' displays:

  86.52 │40055e: → ja   40056c <foo(int, int)+0x26>
  13.37 │400560:   mov  -0x18(%rbp),%eax
        │400563:   add  %eax,-0x14(%rbp)
        │400566:   addl $0x1,-0x4(%rbp)
   0.11 │40056a: → jmp  400557 <foo(int, int)+0x11>
        │40056c:   mov  -0x14(%rbp),%eax
        │40056f:   pop  %rbp

and the 'ja 40056c' does not link to the location in the function.  It's
caused by fact that comma is wrongly parsed, it's part of function
signature.

With my patch I see:

  86.52 │   ┌──ja   26
  13.37 │   │  mov  -0x18(%rbp),%eax
        │   │  add  %eax,-0x14(%rbp)
        │   │  addl $0x1,-0x4(%rbp)
   0.11 │   │↑ jmp  11
        │26:└─→mov  -0x14(%rbp),%eax

and 'o' output prints:

  86.52 │4005┌── ↓ ja   40056c <foo(int, int)+0x26>
  13.37 │4005│0:   mov  -0x18(%rbp),%eax
        │4005│3:   add  %eax,-0x14(%rbp)
        │4005│6:   addl $0x1,-0x4(%rbp)
   0.11 │4005│a: ↑ jmp  400557 <foo(int, int)+0x11>
        │4005└─→   mov  -0x14(%rbp),%eax

On the contrary, compiling the very same file with gcc -x c, the parsing
is fine because function arguments are not displayed:

  jmp  400543 <foo+0x1d>

Committer testing:

Before:

  $ cat cpp_args_annotate.c
  int
  foo(int a, int b)
  {
     for (unsigned i = 0; i < 1000000000; i++)
       a += b;
     return a;
  }

  int main()
  {
     foo (3, 4);
     return 0;
  }
  $ gcc --version |& head -1
  gcc (GCC) 10.2.1 20201125 (Red Hat 10.2.1-9)
  $ gcc -g cpp_args_annotate.c -o cpp_args_annotate
  $ perf record ./cpp_args_annotate
  [ perf record: Woken up 2 times to write data ]
  [ perf record: Captured and wrote 0.275 MB perf.data (7188 samples) ]
  $ perf annotate --stdio2 foo
  Samples: 7K of event 'cycles:u', 4000 Hz, Event count (approx.): 7468429289, [percent: local period]
  foo() /home/acme/c/cpp_args_annotate
  Percent
              0000000000401106 <foo>:
              foo():
              int
              foo(int a, int b)
              {
                push %rbp
                mov  %rsp,%rbp
                mov  %edi,-0x14(%rbp)
                mov  %esi,-0x18(%rbp)
              for (unsigned i = 0; i < 1000000000; i++)
                movl $0x0,-0x4(%rbp)
              ↓ jmp  1d
              a += b;
   13.45  13:   mov  -0x18(%rbp),%eax
                add  %eax,-0x14(%rbp)
              for (unsigned i = 0; i < 1000000000; i++)
                addl $0x1,-0x4(%rbp)
    0.09  1d:   cmpl $0x3b9ac9ff,-0x4(%rbp)
   86.46      ↑ jbe  13
              return a;
                mov  -0x14(%rbp),%eax
              }
                pop  %rbp
              ← retq
  $

I.e. works for C, now lets switch to C++:

  $ g++ -g cpp_args_annotate.c -o cpp_args_annotate
  $ perf record ./cpp_args_annotate
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.268 MB perf.data (6976 samples) ]
  $ perf annotate --stdio2 foo
  Samples: 6K of event 'cycles:u', 4000 Hz, Event count (approx.): 7380681761, [percent: local period]
  foo() /home/acme/c/cpp_args_annotate
  Percent
              0000000000401106 <foo(int, int)>:
              foo(int, int):
              int
              foo(int a, int b)
              {
                push %rbp
                mov  %rsp,%rbp
                mov  %edi,-0x14(%rbp)
                mov  %esi,-0x18(%rbp)
              for (unsigned i = 0; i < 1000000000; i++)
                movl $0x0,-0x4(%rbp)
                cmpl $0x3b9ac9ff,-0x4(%rbp)
   86.53      → ja   40112c <foo(int, int)+0x26>
              a += b;
   13.32        mov  -0x18(%rbp),%eax
    0.00        add  %eax,-0x14(%rbp)
              for (unsigned i = 0; i < 1000000000; i++)
                addl $0x1,-0x4(%rbp)
    0.15      → jmp  401117 <foo(int, int)+0x11>
              return a;
                mov  -0x14(%rbp),%eax
              }
                pop  %rbp
              ← retq
  $

Reproduced.

Now with this patch:

Reusing the C++ built binary, as we can see here:

  $ readelf -wi cpp_args_annotate | grep producer
    <c>   DW_AT_producer    : (indirect string, offset: 0x2e): GNU C++14 10.2.1 20201125 (Red Hat 10.2.1-9) -mtune=generic -march=x86-64 -g
  $

And furthermore:

  $ file cpp_args_annotate
  cpp_args_annotate: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=4fe3cab260204765605ec630d0dc7a7e93c361a9, for GNU/Linux 3.2.0, with debug_info, not stripped
  $ perf buildid-list -i cpp_args_annotate
  4fe3cab260204765605ec630d0dc7a7e93c361a9
  $ perf buildid-list | grep cpp_args_annotate
  4fe3cab260204765605ec630d0dc7a7e93c361a9 /home/acme/c/cpp_args_annotate
  $

It now works:

  $ perf annotate --stdio2 foo
  Samples: 6K of event 'cycles:u', 4000 Hz, Event count (approx.): 7380681761, [percent: local period]
  foo() /home/acme/c/cpp_args_annotate
  Percent
              0000000000401106 <foo(int, int)>:
              foo(int, int):
              int
              foo(int a, int b)
              {
                push %rbp
                mov  %rsp,%rbp
                mov  %edi,-0x14(%rbp)
                mov  %esi,-0x18(%rbp)
              for (unsigned i = 0; i < 1000000000; i++)
                movl $0x0,-0x4(%rbp)
          11:   cmpl $0x3b9ac9ff,-0x4(%rbp)
   86.53      ↓ ja   26
              a += b;
   13.32        mov  -0x18(%rbp),%eax
    0.00        add  %eax,-0x14(%rbp)
              for (unsigned i = 0; i < 1000000000; i++)
                addl $0x1,-0x4(%rbp)
    0.15      ↑ jmp  11
              return a;
          26:   mov  -0x14(%rbp),%eax
              }
                pop  %rbp
              ← retq
  $

Signed-off-by: Martin Liška <mliska@suse.cz>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Link: http://lore.kernel.org/lkml/13e1a405-edf9-e4c2-4327-a9b454353730@suse.cz
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>