[PATCH 2/2] perf: we can now read separate debug-info files based on a build ID

From: Dima Kogan
Date: Mon Sep 07 2015 - 20:34:19 EST

Recent GDB (at least on a vanilla Debian box) looks for debug information in


where nn/nnnnnn is the build-id of the stripped ELF binary. This is documented


This was not working in perf because we didn't read the build id until AFTER we
searched for the separate debug information file. This patch reads the build ID
and THEN does the search.

Signed-off-by: Dima Kogan <dima@xxxxxxxxxxxxxxx>
tools/perf/util/symbol.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 1f97ffb..05c656b 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1406,6 +1406,7 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
struct symsrc ss_[2];
struct symsrc *syms_ss = NULL, *runtime_ss = NULL;
bool kmod;
+ unsigned char build_id[BUILD_ID_SIZE];


@@ -1461,6 +1462,14 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE ||

+ /*
+ * Read the build id if possible. This is required for
+ */
+ if (filename__read_build_id(dso->name, build_id, BUILD_ID_SIZE) > 0)
+ dso__set_build_id(dso, build_id);
* Iterate over candidate debug images.
* Keep track of "interesting" ones (those which have a symtab, dynsym,

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