linux-kernel - Re: [PATCH perf/urgent] perf tools: Fix is_bpf

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Message-ID: <20200512133223.GI28888@kernel.org>
Date:   Tue, 12 May 2020 10:32:23 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>
Subject: Re: [PATCH perf/urgent] perf tools: Fix is_bpf_image function logic

Em Tue, May 12, 2020 at 02:23:10PM +0200, Jiri Olsa escreveu:
> Adrian reported that is_bpf_image is not working the way it was
> intended - passing on trampolines and dispatcher names. Instead
> it returned true for all the bpf names.
> 
> The reason even this logic worked properly is that all bpf objects,
> even trampolines and dispatcher, were assigned DSO_BINARY_TYPE__BPF_IMAGE
> binary_type.
> 
> The later for bpf_prog objects, the binary_type was fixed in bpf load event
> processing, which is executed after the ksymbol code.
> 
> Fixing the is_bpf_image logic, so it properly recognizes trampoline
> and dispatcher objects.

This is not applying on top of torvalds/master, not tip/perf/urgent, and
you forgot to add the Fixes: line, lemme try to find this...

- Arnaldo
 
> Reported-by: Adrian Hunter <adrian.hunter@...el.com>
> Signed-off-by: Jiri Olsa <jolsa@...hat.com>
> ---
>  tools/perf/util/machine.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 8ed2135893bb..d5384807372b 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -738,8 +738,8 @@ int machine__process_switch_event(struct machine *machine __maybe_unused,
>  
>  static int is_bpf_image(const char *name)
>  {
> -	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) ||
> -	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1);
> +	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) == 0 ||
> +	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1) == 0;
>  }
>  
>  static int machine__process_ksymbol_register(struct machine *machine,
> -- 
> 2.25.4
> 

-- 

- Arnaldo