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

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>

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index ce8c07bc8c5626cae48a60fdc76e06fc56f99b1e..e60841b86d279f53645b849838f4b0eb5aa6726d 100644 (file)
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -321,12 +321,18 @@ bool ins__is_call(const struct ins *ins)
 /*
  * Prevents from matching commas in the comment section, e.g.:
  * ffff200008446e70:       b.cs    ffff2000084470f4 <generic_exec_single+0x314>  // b.hs, b.nlast
+ *
+ * and skip comma as part of function arguments, e.g.:
+ * 1d8b4ac <linemap_lookup(line_maps const*, unsigned int)+0xcc>
  */
 static inline const char *validate_comma(const char *c, struct ins_operands *ops)
 {
        if (ops->raw_comment && c > ops->raw_comment)
                return NULL;
 
+       if (ops->raw_func_start && c > ops->raw_func_start)
+               return NULL;
+
        return c;
 }
 
@@ -341,6 +347,8 @@ static int jump__parse(struct arch *arch, struct ins_operands *ops, struct map_s
        u64 start, end;
 
        ops->raw_comment = strchr(ops->raw, arch->objdump.comment_char);
+       ops->raw_func_start = strchr(ops->raw, '<');
+
        c = validate_comma(c, ops);
 
        /*

diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
index 0a0cd4f32175e08a53601698a2500696e3175019..096cdaf21b01f20160654989b88983f81d14b1ee 100644 (file)
--- a/tools/perf/util/annotate.h
+++ b/tools/perf/util/annotate.h
@@ -32,6 +32,7 @@ struct ins {
 struct ins_operands {
        char    *raw;
        char    *raw_comment;
+       char    *raw_func_start;
        struct {
                char    *raw;
                char    *name;