perf symbols: Avoid resolving [kernel.kallsyms] to real path for buildid cache

kallsyms has a virtual file name [kernel.kallsyms].  Currently, it can't
be added to buildid cache successfully because the code
(build_id_cache__add_s) tries to resolve [kernel.kallsyms] to a real
absolute pathname and that fails.

Fixes it by not resolving it and just use the name [kernel.kallsyms].
So dir ~/.debug/[kernel.kallsyms] is created.

Original bug report at:
https://lkml.org/lkml/2011/3/1/524

Tested-by: Han Pingtian <phan@redhat.com>
Cc: Han Pingtian <phan@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1299165837-27817-1-git-send-email-ming.m.lin@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index f6a929e74981..0866bcdb5e8e 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -270,11 +270,15 @@ int build_id_cache__add_s(const char *sbuild_id, const char *debugdir,
                           const char *name, bool is_kallsyms)
 {
         const size_t size = PATH_MAX;
-        char *realname = realpath(name, NULL),
-             *filename = malloc(size),
+        char *realname, *filename = malloc(size),
              *linkname = malloc(size), *targetname;
         int len, err = -1;
 
+        if (is_kallsyms)
+                realname = (char *)name;
+        else
+                realname = realpath(name, NULL);
+
         if (realname == NULL || filename == NULL || linkname == NULL)
                 goto out_free;
 
@@ -306,7 +310,8 @@ int build_id_cache__add_s(const char *sbuild_id, const char *debugdir,
         if (symlink(targetname, linkname) == 0)
                 err = 0;
 out_free:
-        free(realname);
+        if (!is_kallsyms)
+                free(realname);
         free(filename);
         free(linkname);
         return err;