perf symbols: Fix ELF header errors during "perf kmem record"

The write_event() function in builtin-record.c writes out all
mmap()'d DSOs including non-ELF files like GNOME resource files
and such.

Therefore, check for ELF_K_ELF in filename__read_build_id()
before attempting to read the ELF header with gelf_getehdr().

Fixes the following error messages when running "perf kmem
record":

  penberg@penberg-laptop:~/src/linux/tools/perf$ perf kmem record
  ^C[ perf record: Woken up 2 times to write data ]
  [ perf record: Captured and wrote 0.753 MB perf.data (~32885 samples) ]
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.
  filename__read_build_id: cannot get elf header.

Signed-off-by: Pekka Enberg <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Steven Rostedt <[email protected]>
LKML-Reference: <1258885784[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 86ec6c720f0f8f9be384147bdecba1c9cff3ffa6..f56158fb4dc9d09d68281b33f733473688bc56ca 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -921,6 +921,7 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)
        GElf_Shdr shdr;
        Elf_Data *data;
        Elf_Scn *sec;
+       Elf_Kind ek;
        void *ptr;
        Elf *elf;
 
@@ -937,6 +938,10 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)
                goto out_close;
        }
 
+       ek = elf_kind(elf);
+       if (ek != ELF_K_ELF)
+               goto out_elf_end;
+
        if (gelf_getehdr(elf, &ehdr) == NULL) {
                pr_err("%s: cannot get elf header.\n", __func__);
                goto out_elf_end;