linux-kernel - [PATCH 1/2] perf-probe: Ensure debuginfo's build-id is correct

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Message-Id: <151358214328.25261.6660021248431426149.stgit@devbox>
Date:   Mon, 18 Dec 2017 16:29:03 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: [PATCH 1/2] perf-probe: Ensure debuginfo's build-id is correct

Ensure that the build-id of debuginfo is correctly
matched to target build-id, if not, it warns user
to check the system debuginfo package is correctly
installed.

E.g. on such environment, you will see below warning.
  ======
  # perf probe -l
  WARN: There is a build-id mismatch between
   /usr/lib/debug/usr/lib64/libc-2.25.so.debug
   and
   /usr/lib64/libc-2.25.so
  Please check your system's debuginfo files for mismatches, e.g. check
  the versions for the target package and debuginfo package.
    probe_libc:malloc_get_state (on malloc_get_state@...BC_2.2.5 in /us
  r/lib64/libc-2.25.so)
  ======

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 tools/perf/util/probe-finder.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index a5731de0e5eb..5bb71e056b21 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -119,9 +119,11 @@ enum dso_binary_type distro_dwarf_types[] = {
 
 struct debuginfo *debuginfo__new(const char *path)
 {
+	u8 bid[BUILD_ID_SIZE], bid2[BUILD_ID_SIZE];
 	enum dso_binary_type *type;
 	char buf[PATH_MAX], nil = '\0';
 	struct dso *dso;
+	bool have_build_id = false;
 	struct debuginfo *dinfo = NULL;
 
 	/* Try to open distro debuginfo files */
@@ -129,12 +131,28 @@ struct debuginfo *debuginfo__new(const char *path)
 	if (!dso)
 		goto out;
 
+	if (filename__read_build_id(path, bid, BUILD_ID_SIZE) > 0)
+		have_build_id = true;
+
 	for (type = distro_dwarf_types;
 	     !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
 	     type++) {
 		if (dso__read_binary_type_filename(dso, *type, &nil,
 						   buf, PATH_MAX) < 0)
 			continue;
+
+		if (have_build_id) {
+			/* This can be fail because the file doesn't exist */
+			if (filename__read_build_id(buf, bid2,
+						    BUILD_ID_SIZE) < 0)
+				continue;
+			if (memcmp(bid, bid2, BUILD_ID_SIZE)) {
+				pr_warning("WARN: There is a build-id mismatch between\n %s\n and\n %s\n"
+					"Please check your system's debuginfo files for mismatches, e.g. check the "
+					"versions for the target package and debuginfo package.\n", buf, path);
+				continue;
+			}
+		}
 		dinfo = __debuginfo__new(buf);
 	}
 	dso__put(dso);