linux-kernel - [PATCH 1/4] perf buildid-cache: Don't skip 16-byte build-ids

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Date:   Wed, 10 Feb 2021 14:17:25 -0500
From:   Nicholas Fraser <nfraser@...eweavers.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        "Frank Ch. Eigler" <fche@...hat.com>,
        Song Liu <songliubraving@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kim Phillips <kim.phillips@....com>,
        Tommi Rantala <tommi.t.rantala@...ia.com>,
        Remi Bernon <rbernon@...eweavers.com>,
        linux-kernel@...r.kernel.org
Cc:     Ulrich Czekalla <uczekalla@...eweavers.com>,
        Huw Davies <huw@...eweavers.com>
Subject: [PATCH 1/4] perf buildid-cache: Don't skip 16-byte build-ids

lsdir_bid_tail_filter() ignored any build-id that wasn't exactly 20
bytes. This worked only for SHA-1 build-ids. The build-id for a PE file
is always a 16-byte GUID and ELF files can also have MD5 or UUID
build-ids.

This fix changes the filter to allow build-ids between 16 and 20 bytes.

Signed-off-by: Nicholas Fraser <nfraser@...eweavers.com>
---
 tools/perf/util/build-id.c | 5 +++--
 tools/perf/util/build-id.h | 4 +++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 02df36b30ac5..e32e8f2ff3bd 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -448,7 +448,8 @@ static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
 	int i = 0;
 	while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
 		i++;
-	return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
+	return (i >= SBUILD_ID_MIN_SIZE - 3) && (i <= SBUILD_ID_SIZE - 3) &&
+		(d->d_name[i] == '\0');
 }
 
 struct strlist *build_id_cache__list_all(bool validonly)
@@ -490,7 +491,7 @@ struct strlist *build_id_cache__list_all(bool validonly)
 		}
 		strlist__for_each_entry(nd2, linklist) {
 			if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
-				     nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
+				     nd->s, nd2->s) > SBUILD_ID_SIZE - 1)
 				goto err_out;
 			if (validonly && !build_id_cache__valid_id(sbuild_id))
 				continue;
diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
index 02613f4b2c29..c19617151670 100644
--- a/tools/perf/util/build-id.h
+++ b/tools/perf/util/build-id.h
@@ -2,8 +2,10 @@
 #ifndef PERF_BUILD_ID_H_
 #define PERF_BUILD_ID_H_ 1
 
-#define BUILD_ID_SIZE	20
+#define BUILD_ID_SIZE	20 /* SHA-1 length in bytes */
+#define BUILD_ID_MIN_SIZE	16 /* MD5/UUID/GUID length in bytes */
 #define SBUILD_ID_SIZE	(BUILD_ID_SIZE * 2 + 1)
+#define SBUILD_ID_MIN_SIZE	(BUILD_ID_MIN_SIZE * 2 + 1)
 
 #include "machine.h"
 #include "tool.h"
-- 
2.30.0