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

From: Jiri Olsa
Date: Wed Feb 17 2021 - 14:27:33 EST


On Tue, Feb 16, 2021 at 11:35:06AM -0500, Nicholas Fraser wrote:
> No problem, I've added a call to "perf buildid-cache -l" in check() to make
> sure the added IDs are reported. The MD5 test fails without the previous
> patch to allow 16-byte build-ids.
>
> Do you also want PE files tested by this test script? This would make the
> script depend on a number of things:
>
> - We'd need to change "readelf" to something that can read the build-id of
> PE files;
>
> - We'd need MinGW installed to build them on the fly the same as the ELF
> test cases, although we could use tests/pe-file.exe instead which is
> already included;
>
> - We'd need Wine to actually run it under perf record, which I'm sure you
> don't want to depend on;
>
> - We'd need to detect whether perf was built with libbfd support. Easily
> done by calling perf version --build-options but by this point the test
> case is getting pretty out of hand for what it's supposed to test.

right, that's a lot of dependencies ;-) but I don't mind having
separate script (PE specific) checking on all that, and printing
'SKIP' if some dependency is not there

I guess it will take some time to configure the system, but it will
make sure we won't break anything for you in future

thanks,
jirka

>
> I'll send patches for this test without PE support. It still tests 16-byte
> build-ids because it tests an MD5 ELF file. Let me know if you also want me
> to add PE support to this script. We can make it optionally perform PE
> tests if all of the necessary tools are installed but it would take some
> pretty large changes to the script.
>
> Nick
>
>
> On 2021-02-15 9:31 a.m., Jiri Olsa wrote:
> > 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.
> >
> > hi,
> > there's tests/shell/buildid.sh test for this, please add
> > testcase for this.. looks like perf buildid-cacle -l will
> > end up calling this function
> >
> > thanks,
> > jirka
> >
> >>
> >> Signed-off-by: Nicholas Fraser <nfraser@xxxxxxxxxxxxxxx>
> >> ---
> >> 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
> >>
> >
>