perf symbols: Workaround objdump difficulties with kcore

The objdump tool fails to annotate module symbols when looking at kcore.

Workaround this by extracting object code from kcore and putting it in a
temporary file for objdump to use instead.

The temporary file is created to look like kcore but contains only the
function being disassembled.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1381320078-16497-3-git-send-email-adrian.hunter@intel.com
[ Renamed 'index' to 'idx' to avoid shadowing string.h's 'index' in Fedora 12,
  Replace local with variable length with malloc/free to fix build in Fedora 12 ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index d73e8008aada..882bb864cee0 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -879,6 +879,8 @@ int symbol__annotate(struct symbol *sym, struct map *map, size_t privsize)
         FILE *file;
         int err = 0;
         char symfs_filename[PATH_MAX];
+        struct kcore_extract kce;
+        bool delete_extract = false;
 
         if (filename) {
                 snprintf(symfs_filename, sizeof(symfs_filename), "%s%s",
@@ -940,6 +942,23 @@ fallback:
         pr_debug("annotating [%p] %30s : [%p] %30s\n",
                  dso, dso->long_name, sym, sym->name);
 
+        if (dso__is_kcore(dso)) {
+                kce.kcore_filename = symfs_filename;
+                kce.addr = map__rip_2objdump(map, sym->start);
+                kce.offs = sym->start;
+                kce.len = sym->end + 1 - sym->start;
+                if (!kcore_extract__create(&kce)) {
+                        delete_extract = true;
+                        strlcpy(symfs_filename, kce.extract_filename,
+                                sizeof(symfs_filename));
+                        if (free_filename) {
+                                free(filename);
+                                free_filename = false;
+                        }
+                        filename = symfs_filename;
+                }
+        }
+
         snprintf(command, sizeof(command),
                  "%s %s%s --start-address=0x%016" PRIx64
                  " --stop-address=0x%016" PRIx64
@@ -972,6 +991,8 @@ fallback:
 
         pclose(file);
 out_free_filename:
+        if (delete_extract)
+                kcore_extract__delete(&kce);
         if (free_filename)
                 free(filename);
         return err;