linux-kernel - Re: [PATCH 06/15] perf tools: Add support to read build id from compressed elf

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Date:   Tue, 15 Dec 2020 12:55:03 -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>,
        Alexei Budankov <abudankov@...wei.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 06/15] perf tools: Add support to read build id from
 compressed elf

Em Mon, Dec 14, 2020 at 11:54:48AM +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

Tentatively cherry picking this one.

- Arnaldo
 
> 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.
> 
> 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..3d31c1d560d6 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* 2>/dev/null | 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