linux-kernel - Re: [PATCH 09/25] perf tools: Add support to read build id from compressed elf

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Date:   Thu, 26 Nov 2020 14:46:20 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Song Liu <songliubraving@...com>,
        Ian Rogers <irogers@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 09/25] perf tools: Add support to read build id from
 compressed elf

Em Thu, Nov 26, 2020 at 06:00:10PM +0100, Jiri Olsa escreveu:
> Adding support to decompress file before reading build id.
> 
> Adding filename__read_build_id and change its current
> versions to read_build_id.
> 
> Shutting down stderr output of perf list in the shell test:
>   82: Check open filename arg using perf trace + vfs_getname          : Ok
> 
> because with decompression code in the place we the
> filename__read_build_id function is more verbose in case
> of error and the test did not account for that.

There are two patches here, right? Also the test output shows it after,
before is missing, showing what the test wasn't accounting for.

- Arnaldo
 
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  .../tests/shell/trace+probe_vfs_getname.sh    |  2 +-
>  tools/perf/util/symbol-elf.c                  | 37 ++++++++++++++++++-
>  2 files changed, 36 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/tests/shell/trace+probe_vfs_getname.sh b/tools/perf/tests/shell/trace+probe_vfs_getname.sh
> index 11cc2af13f2b..3660fcc02fef 100755
> --- a/tools/perf/tests/shell/trace+probe_vfs_getname.sh
> +++ b/tools/perf/tests/shell/trace+probe_vfs_getname.sh
> @@ -20,7 +20,7 @@ skip_if_no_perf_trace || exit 2
>  file=$(mktemp /tmp/temporary_file.XXXXX)
>  
>  trace_open_vfs_getname() {
> -	evts=$(echo $(perf list syscalls:sys_enter_open* 2>&1 | egrep 'open(at)? ' | sed -r 's/.*sys_enter_([a-z]+) +\[.*$/\1/') | sed 's/ /,/')
> +	evts=$(echo $(perf list syscalls:sys_enter_open* >&1 2>/dev/nul | egrep 'open(at)? ' | sed -r 's/.*sys_enter_([a-z]+) +\[.*$/\1/') | sed 's/ /,/')
>  	perf trace -e $evts touch $file 2>&1 | \
>  	egrep " +[0-9]+\.[0-9]+ +\( +[0-9]+\.[0-9]+ ms\): +touch\/[0-9]+ open(at)?\((dfd: +CWD, +)?filename: +${file}, +flags: CREAT\|NOCTTY\|NONBLOCK\|WRONLY, +mode: +IRUGO\|IWUGO\) += +[0-9]+$"
>  }
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index 44dd86a4f25f..f3577f7d72fe 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -534,7 +534,7 @@ static int elf_read_build_id(Elf *elf, void *bf, size_t size)
>  
>  #ifdef HAVE_LIBBFD_BUILDID_SUPPORT
>  
> -int filename__read_build_id(const char *filename, struct build_id *bid)
> +static int read_build_id(const char *filename, struct build_id *bid)
>  {
>  	size_t size = sizeof(bid->data);
>  	int err = -1;
> @@ -563,7 +563,7 @@ int filename__read_build_id(const char *filename, struct build_id *bid)
>  
>  #else // HAVE_LIBBFD_BUILDID_SUPPORT
>  
> -int filename__read_build_id(const char *filename, struct build_id *bid)
> +static int read_build_id(const char *filename, struct build_id *bid)
>  {
>  	size_t size = sizeof(bid->data);
>  	int fd, err = -1;
> @@ -595,6 +595,39 @@ int filename__read_build_id(const char *filename, struct build_id *bid)
>  
>  #endif // HAVE_LIBBFD_BUILDID_SUPPORT
>  
> +int filename__read_build_id(const char *filename, struct build_id *bid)
> +{
> +	struct kmod_path m = { .name = NULL, };
> +	char path[PATH_MAX];
> +	int err;
> +
> +	if (!filename)
> +		return -EFAULT;
> +
> +	err = kmod_path__parse(&m, filename);
> +	if (err)
> +		return -1;
> +
> +	if (m.comp) {
> +		int error = 0, fd;
> +
> +		fd = filename__decompress(filename, path, sizeof(path), m.comp, &error);
> +		if (fd < 0) {
> +			pr_debug("Failed to decompress (error %d) %s\n",
> +				 error, filename);
> +			return -1;
> +		}
> +		close(fd);
> +		filename = path;
> +	}
> +
> +	err = read_build_id(filename, bid);
> +
> +	if (m.comp)
> +		unlink(filename);
> +	return err;
> +}
> +
>  int sysfs__read_build_id(const char *filename, struct build_id *bid)
>  {
>  	size_t size = sizeof(bid->data);
> -- 
> 2.26.2
> 

-- 

- Arnaldo