linux-kernel - Re: [PATCH 4/4] perf annotate: More exactly grep -v of the objdump command

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Date:   Tue, 21 Mar 2017 11:37:28 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Taeung Song <treeze.taeung@...il.com>
Cc:     linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Wang Nan <wangnan0@...wei.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH 4/4] perf annotate: More exactly grep -v of the objdump
 command

Em Mon, Mar 20, 2017 at 11:56:57AM +0900, Taeung Song escreveu:
> grep -v "file name" in the objdump command
> cause a side effect eliminating filename:linenr of
> output of 'objdump -l' if the object file name and
> source file name are about the same so fix it.
> 
> The objdump command in symbol__disassemble() can be as below
> 
>     $ objdump -l -d -S -C /home/taeung/hello --start-address=...
> 
>     /home/taeung/hello:     file format elf64-x86-64
> 
>     Disassembly of section .text:
> 
>     0000000000400526 <main>:
>     main():
>     /home/taeung/hello.c:4
> 
>     void main()
>     {
>       400526:	55                   	push   %rbp
>       400527:	48 89 e5             	mov    %rsp,%rbp
>     /home/taeung/hello.c:5
>     ...
> 
> But currently it use grep -v "file name" e.g. "/home/taeung/hello"
> in the objdump command to remove the first line containing file name
> and file format such as,
> 
> Before:
>     $ objdump -l -d -S -C /home/taeung/hello | grep /home/taeung/hello
> 
> But it cause a side effect removing filename:linenr
> because the object file and source file has same name
> e.g. "/home/taueng/hello", "/home/taeung/hello.c"
> 
> So more exactly grep -v as below
> to correctly remove the one line
> e.g. "/home/taeung/hello:     file format elf64-x86-64"
> 
> After:
>     $ objdump -l -d -S -C /home/taeung/hello | grep /home/taeung/hello:

What environment is this? I tried to reproduce this here but got
different results, and I had to figure out the 'perf record' you used,
you forgot to mention it, i.e. 'perf record ./hello' doesn't work, one
has to use 'perf record /full/path/to/hello', anyway, with my
environemnt, which is:

[root@...et ~]# objdump -v
GNU objdump version 2.26.1-1.fc25

I end up getting:

Sorted summary for file /home/acme/c/hello
----------------------------------------------

   52.67 hello.c:7
   47.32 hello.c:8
 Percent |      Source code & Disassembly of hello for cycles:u (83555 samples)
-------------------------------------------------------------------------------
         :      00000000004004f6 <main>:
         :      main():
         :      #include <stdio.h>
         :
         :      int main(void)
         :      {
    0.00 :        4004f6:       push   %rbp
    0.00 :        4004f7:       mov    %rsp,%rbp
    0.00 :        4004fa:       sub    $0x10,%rsp
         :              unsigned long long i;
         :              printf("hello, world\n");
    0.00 :        4004fe:       mov    $0x4005d0,%edi
    0.00 :        400503:       callq  4003f0 <puts@plt>
         :              while (i < (unsigned long long)-1) {
    0.00 :        400508:       jmp    40052d <main+0x37>
         :                      i *= 171;
 hello.c:8    8.66 :      40050a:       mov    -0x8(%rbp),%rdx
    0.01 :        40050e:       mov    %rdx,%rax
    0.00 :        400511:       shl    $0x3,%rax
 hello.c:8    0.84 :      400515:       add    %rdx,%rax
 hello.c:8    8.60 :      400518:       add    %rax,%rax
 hello.c:8    3.46 :      40051b:       add    %rdx,%rax
 hello.c:8    8.57 :      40051e:       lea    0x0(,%rax,8),%rdx
    8.65 :        400526:       add    %rdx,%rax
    8.56 :        400529:       mov    %rax,-0x8(%rbp)
<SNIP>

Which looks ok, i.e. since this version of objdump puts just the basename (hello.c),
that grep doesn't nuke it.

But yeah, your patch is more robust, just fix what I described below, i.e. use
quotes in the grep -v bit, probably.

- Arnaldo
 
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Jiri Olsa <jolsa@...hat.com>
> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
> ---
>  tools/perf/util/annotate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
> index 63130ec..e49eb7e 100644
> --- a/tools/perf/util/annotate.c
> +++ b/tools/perf/util/annotate.c
> @@ -1443,7 +1443,7 @@ int symbol__disassemble(struct symbol *sym, struct map *map, const char *arch_na
>  	snprintf(command, sizeof(command),
>  		 "%s %s%s --start-address=0x%016" PRIx64
>  		 " --stop-address=0x%016" PRIx64
> -		 " -l -d %s %s -C %s 2>/dev/null|grep -v %s|expand",
> +		 " -l -d %s %s -C %s 2>/dev/null|grep -v %s: |expand",


Are you sure this works as you expect? I.e. both lines will have '%s:'
that space just before the '|' will not be considered by grep

>  		 objdump_path ? objdump_path : "objdump",
>  		 disassembler_style ? "-M " : "",
>  		 disassembler_style ? disassembler_style : "",
> -- 
> 2.7.4