perf symbols: Introduce symsrc structure.

Factors opening of certain sections & tracking certain elf info into an
external structure.

The goal here is to keep multiple elfs (and their looked up
sections/indexes) around during the symbol generation process (in
dso__load()).

We need this to properly resolve symbols on PPC due to the use of
function descriptors & the .opd section (ie: symbols which are functions
don't point to their actual location, they point to their function
descriptor in .opd which contains their actual location.

It would be possible to just keep the (Elf *) around, but then we'd end
up with duplicate code for looking up the same sections and checking for
the existence of an important section wouldn't be as clean (and we need
to keep the Elf stuff confined to symtab-elf.c).

Utilized by the later patch
"perf symbols: Use both runtime and debug images"

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Matt Hellsley <matthltc@us.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1344637382-22789-12-git-send-email-cody@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 27 insertions, 3 deletions

diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index bd8720b6780c..1b16c2729a36 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -241,6 +241,31 @@ out:
         return ret;
 }
 
+int symsrc__init(struct symsrc *ss, struct dso *dso __used, const char *name,
+                 enum dso_binary_type type)
+{
+        int fd = open(name, O_RDONLY);
+        if (fd < 0)
+                return -1;
+
+        ss->name = strdup(name);
+        if (!ss->name)
+                goto out_close;
+
+        ss->type = type;
+
+        return 0;
+out_close:
+        close(fd);
+        return -1;
+}
+
+void symsrc__destroy(struct symsrc *ss)
+{
+        free(ss->name);
+        close(ss->fd);
+}
+
 int dso__synthesize_plt_symbols(struct dso *dso __used, char *name __used,
                                 struct map *map __used,
                                 symbol_filter_t filter __used)
@@ -248,14 +273,13 @@ int dso__synthesize_plt_symbols(struct dso *dso __used, char *name __used,
         return 0;
 }
 
-int dso__load_sym(struct dso *dso, struct map *map __used,
-                  const char *name, int fd __used,
+int dso__load_sym(struct dso *dso, struct map *map __used, struct symsrc *ss,
                   symbol_filter_t filter __used, int kmodule __used,
                   int want_symtab __used)
 {
         unsigned char *build_id[BUILD_ID_SIZE];
 
-        if (filename__read_build_id(name, build_id, BUILD_ID_SIZE) > 0) {
+        if (filename__read_build_id(ss->name, build_id, BUILD_ID_SIZE) > 0) {
                 dso__set_build_id(dso, build_id);
                 return 1;
         }