perf header: Set proper module name when build-id event found

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 <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
[ Fix the build on older compilers (debian <= 8, fedora <= 21, etc) wrt kmod_path var init ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions