lkml.org 
[lkml]   [2017]   [May]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 1/3] perf tools: Set proper module name when build-id event found
    Date
    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>
    ---
    tools/perf/util/header.c | 12 ++++++++++--
    1 file changed, 10 insertions(+), 2 deletions(-)

    diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
    index 314a07151fb7..56b8a479223b 100644
    --- a/tools/perf/util/header.c
    +++ b/tools/perf/util/header.c
    @@ -1469,8 +1469,16 @@ static int __event_process_build_id(struct build_id_event *bev,

    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 = {};
    +
    + 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);
    --
    2.13.0
    \
     
     \ /
      Last update: 2017-05-31 14:01    [W:3.982 / U:0.036 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site