Re: [PATCH 1/4] perf buildid-cache: Don't skip 16-byte build-ids

From: Jiri Olsa <jolsa@redhat.com>
To: Nicholas Fraser <nfraser@codeweavers.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Ian Rogers <irogers@google.com>,
	"Frank Ch. Eigler" <fche@redhat.com>,
	Song Liu <songliubraving@fb.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Kim Phillips <kim.phillips@amd.com>,
	Tommi Rantala <tommi.t.rantala@nokia.com>,
	Remi Bernon <rbernon@codeweavers.com>,
	linux-kernel@vger.kernel.org,
	Ulrich Czekalla <uczekalla@codeweavers.com>,
	Huw Davies <huw@codeweavers.com>
Subject: Re: [PATCH 1/4] perf buildid-cache: Don't skip 16-byte build-ids
Date: Wed, 17 Feb 2021 20:54:00 +0100	[thread overview]
Message-ID: <YC10WPYjps4Z0H8B@krava> (raw)
In-Reply-To: <597788e4-661d-633f-857c-3de700115d02@codeweavers.com>

On Wed, Feb 10, 2021 at 02:17:25PM -0500, Nicholas Fraser wrote:
> lsdir_bid_tail_filter() ignored any build-id that wasn't exactly 20
> bytes. This worked only for SHA-1 build-ids. The build-id for a PE file
> is always a 16-byte GUID and ELF files can also have MD5 or UUID
> build-ids.
> 
> This fix changes the filter to allow build-ids between 16 and 20 bytes.
> 
> Signed-off-by: Nicholas Fraser <nfraser@codeweavers.com>

Acked-by: Jiri Olsa <jolsa@redhat.com>

thanks,
jirka

> ---
>  tools/perf/util/build-id.c | 5 +++--
>  tools/perf/util/build-id.h | 4 +++-
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index 02df36b30ac5..e32e8f2ff3bd 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -448,7 +448,8 @@ static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
>  	int i = 0;
>  	while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
>  		i++;
> -	return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
> +	return (i >= SBUILD_ID_MIN_SIZE - 3) && (i <= SBUILD_ID_SIZE - 3) &&
> +		(d->d_name[i] == '\0');
>  }
>  
>  struct strlist *build_id_cache__list_all(bool validonly)
> @@ -490,7 +491,7 @@ struct strlist *build_id_cache__list_all(bool validonly)
>  		}
>  		strlist__for_each_entry(nd2, linklist) {
>  			if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
> -				     nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
> +				     nd->s, nd2->s) > SBUILD_ID_SIZE - 1)
>  				goto err_out;
>  			if (validonly && !build_id_cache__valid_id(sbuild_id))
>  				continue;
> diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
> index 02613f4b2c29..c19617151670 100644
> --- a/tools/perf/util/build-id.h
> +++ b/tools/perf/util/build-id.h
> @@ -2,8 +2,10 @@
>  #ifndef PERF_BUILD_ID_H_
>  #define PERF_BUILD_ID_H_ 1
>  
> -#define BUILD_ID_SIZE	20
> +#define BUILD_ID_SIZE	20 /* SHA-1 length in bytes */
> +#define BUILD_ID_MIN_SIZE	16 /* MD5/UUID/GUID length in bytes */
>  #define SBUILD_ID_SIZE	(BUILD_ID_SIZE * 2 + 1)
> +#define SBUILD_ID_MIN_SIZE	(BUILD_ID_MIN_SIZE * 2 + 1)
>  
>  #include "machine.h"
>  #include "tool.h"
> -- 
> 2.30.0
>