From: Martin Liška mliska@suse.cz
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 --- tools/perf/util/annotate.c | 8 ++++++++ tools/perf/util/annotate.h | 1 + 2 files changed, 9 insertions(+)
--- a/tools/perf/util/annotate.c +++ b/tools/perf/util/annotate.c @@ -317,12 +317,18 @@ 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; }
@@ -337,6 +343,8 @@ static int jump__parse(struct arch *arch 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);
/* --- 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;