This is a note to let you know that I've just added the patch titled
perf header: Set proper module name when build-id event found
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: perf-header-set-proper-module-name-when-build-id-event-found.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Apr 9 17:09:24 CEST 2018
From: Namhyung Kim namhyung@kernel.org Date: Wed, 31 May 2017 21:01:03 +0900 Subject: perf header: Set proper module name when build-id event found
From: Namhyung Kim namhyung@kernel.org
[ Upstream commit 1deec1bd96ccd8beb04d2112a6d12fe20505c3a6 ]
When perf processes build-id event, it creates DSOs with the build-id. But it didn't set the module short name (like '[module-name]') so when processing a kernel mmap event of the module, it cannot found the DSO as it only checks the short names.
That leads for perf to create a same DSO without the build-id info and it'll lookup the system path even if the DSO is already in the build-id cache. After kernel was updated, perf cannot find the DSO and cannot show symbols in it anymore.
You can see this if you have an old data file (w/ old kernel version):
$ perf report -i perf.data.old -v |& grep scsi_mod build id event received for /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz : cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1 Failed to open /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz, continuing without symbols ...
The second message didn't show the build-id. With this patch:
$ perf report -i perf.data.old -v |& grep scsi_mod build id event received for /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz: cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1 /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz with build id cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1 not found, continuing without symbols ...
Now it shows the build-id but still cannot load the symbol table. This is a different problem which will be fixed in the next patch.
Signed-off-by: Namhyung Kim namhyung@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org Cc: Andi Kleen andi@firstfloor.org Cc: David Ahern dsahern@gmail.com Cc: Peter Zijlstra a.p.zijlstra@chello.nl Cc: kernel-team@lge.com Link: http://lkml.kernel.org/r/20170531120105.21731-1-namhyung@kernel.org [ Fix the build on older compilers (debian <= 8, fedora <= 21, etc) wrt kmod_path var init ] Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/perf/util/header.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
--- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -1454,8 +1454,16 @@ static int __event_process_build_id(stru
dso__set_build_id(dso, &bev->build_id);
- if (!is_kernel_module(filename, cpumode)) - dso->kernel = dso_type; + if (dso_type != DSO_TYPE_USER) { + struct kmod_path m = { .name = NULL, }; + + if (!kmod_path__parse_name(&m, filename) && m.kmod) + dso__set_short_name(dso, strdup(m.name), true); + else + dso->kernel = dso_type; + + free(m.name); + }
build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
Patches currently in stable-queue which might be from namhyung@kernel.org are
queue-4.9/perf-report-fix-off-by-one-for-non-activation-frames.patch queue-4.9/perf-trace-add-mmap-alias-for-s390.patch queue-4.9/perf-report-ensure-the-perf-dso-mapping-matches-what-libdw-sees.patch queue-4.9/perf-tools-fix-copyfile_offset-update-of-output-offset.patch queue-4.9/perf-tools-decompress-kernel-module-when-reading-dso-data.patch queue-4.9/perf-tests-decompress-kernel-module-before-objdump.patch queue-4.9/perf-header-set-proper-module-name-when-build-id-event-found.patch