perf tools: Back [vdso] DSO with real data

Storing data for VDSO shared object, because we need it for the post
unwind processing.

The VDSO shared object is same for all process on a running system, so
it makes no difference when we store it inside the tracer - perf.

When [vdso] map memory is hit, we retrieve [vdso] DSO image and store it
into temporary file.

During the build-id processing phase, the [vdso] DSO image is stored in
build-id db, and build-id reference is made inside perf.data. The
build-id vdso file object is called '[vdso]'. We don't use temporary
file name which gets removed when record is finished.

During report phase the vdso build-id object is treated as any other
build-id DSO object.

Adding following API for vdso object:

  bool is_vdso_map(const char *filename)
    - returns true if the filename matches vdso map name

  struct dso *vdso__dso_findnew(struct list_head *head)
    - find/create proper vdso DSO object

  vdso__exit(void)
    - removes temporary VDSO image if there's any

This change makes backtrace dwarf post unwind possible from [vdso] maps.

Following output is current report of [vdso] sample dwarf backtrace:

  # Overhead  Command      Shared Object                         Symbol
  # ........  .......  .................  .............................
  #
      99.52%       ex  [vdso]             [.] 0x00007fff3ace89af
                   |
                   --- 0x7fff3ace89af

Following output is new report of [vdso] sample dwarf backtrace:

  # Overhead  Command      Shared Object                         Symbol
  # ........  .......  .................  .............................
  #
      99.52%       ex  [vdso]             [.] 0x00000000000009af
                   |
                   --- 0x7fff3ace89af
                       main
                       __libc_start_main
                       _start

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347295819-23177-5-git-send-email-jolsa@redhat.com
[ committer note: s/ALIGN/PERF_ALIGN/g to cope with the android build changes ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 9d5eedceda7..209dad4fee2 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -96,7 +96,7 @@ int perf_header__process_sections(struct perf_header *header, int fd,
 int perf_header__fprintf_info(struct perf_session *s, FILE *fp, bool full);
 
 int build_id_cache__add_s(const char *sbuild_id, const char *debugdir,
-			  const char *name, bool is_kallsyms);
+			  const char *name, bool is_kallsyms, bool is_vdso);
 int build_id_cache__remove_s(const char *sbuild_id, const char *debugdir);
 
 int perf_event__synthesize_attr(struct perf_tool *tool,