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Message-ID: <20251112074311.1440101-1-irogers@google.com>
Date: Tue, 11 Nov 2025 23:43:11 -0800
From: Ian Rogers <irogers@...gle.com>
To: Guilherme Amadio <amadio@...too.org>, Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] perf libbfd: Ensure libbfd is initialized prior to use
Multiple threads may be creating and destroying BFD objects in
situations like `perf top`. Without appropriate initialization crashes
may occur during libbfd's cache management. BFD's locks require
recursive mutexes, add support for these.
Reported-by: Guilherme Amadio <amadio@...too.org>
Closes: https://lore.kernel.org/lkml/aQt66zhfxSA80xwt@gentoo.org/
Fixes: 95931d9a594d ("perf libbfd: Move libbfd functionality to its own file")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
v2: Remove unneeded unistd.h include.
---
tools/perf/util/libbfd.c | 38 ++++++++++++++++++++++++++++++++++++++
tools/perf/util/mutex.c | 14 ++++++++++----
tools/perf/util/mutex.h | 2 ++
3 files changed, 50 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/libbfd.c b/tools/perf/util/libbfd.c
index 01147fbf73b3..6434c2dccd4a 100644
--- a/tools/perf/util/libbfd.c
+++ b/tools/perf/util/libbfd.c
@@ -38,6 +38,39 @@ struct a2l_data {
asymbol **syms;
};
+static bool perf_bfd_lock(void *bfd_mutex)
+{
+ mutex_lock(bfd_mutex);
+ return true;
+}
+
+static bool perf_bfd_unlock(void *bfd_mutex)
+{
+ mutex_unlock(bfd_mutex);
+ return true;
+}
+
+static void perf_bfd_init(void)
+{
+ static struct mutex bfd_mutex;
+
+ mutex_init_recursive(&bfd_mutex);
+
+ if (bfd_init() != BFD_INIT_MAGIC) {
+ pr_err("Error initializing libbfd\n");
+ return;
+ }
+ if (!bfd_thread_init(perf_bfd_lock, perf_bfd_unlock, &bfd_mutex))
+ pr_err("Error initializing libbfd threading\n");
+}
+
+static void ensure_bfd_init(void)
+{
+ static pthread_once_t bfd_init_once = PTHREAD_ONCE_INIT;
+
+ pthread_once(&bfd_init_once, perf_bfd_init);
+}
+
static int bfd_error(const char *string)
{
const char *errmsg;
@@ -132,6 +165,7 @@ static struct a2l_data *addr2line_init(const char *path)
bfd *abfd;
struct a2l_data *a2l = NULL;
+ ensure_bfd_init();
abfd = bfd_openr(path, NULL);
if (abfd == NULL)
return NULL;
@@ -288,6 +322,7 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile)
bfd *abfd;
u64 start, len;
+ ensure_bfd_init();
abfd = bfd_openr(debugfile, NULL);
if (!abfd)
return -1;
@@ -393,6 +428,7 @@ int libbfd__read_build_id(const char *filename, struct build_id *bid, bool block
if (fd < 0)
return -1;
+ ensure_bfd_init();
abfd = bfd_fdopenr(filename, /*target=*/NULL, fd);
if (!abfd)
return -1;
@@ -421,6 +457,7 @@ int libbfd_filename__read_debuglink(const char *filename, char *debuglink,
asection *section;
bfd *abfd;
+ ensure_bfd_init();
abfd = bfd_openr(filename, NULL);
if (!abfd)
return -1;
@@ -480,6 +517,7 @@ int symbol__disassemble_bpf_libbfd(struct symbol *sym __maybe_unused,
memset(tpath, 0, sizeof(tpath));
perf_exe(tpath, sizeof(tpath));
+ ensure_bfd_init();
bfdf = bfd_openr(tpath, NULL);
if (bfdf == NULL)
abort();
diff --git a/tools/perf/util/mutex.c b/tools/perf/util/mutex.c
index bca7f0717f35..7aa1f3f55a7d 100644
--- a/tools/perf/util/mutex.c
+++ b/tools/perf/util/mutex.c
@@ -17,7 +17,7 @@ static void check_err(const char *fn, int err)
#define CHECK_ERR(err) check_err(__func__, err)
-static void __mutex_init(struct mutex *mtx, bool pshared)
+static void __mutex_init(struct mutex *mtx, bool pshared, bool recursive)
{
pthread_mutexattr_t attr;
@@ -27,21 +27,27 @@ static void __mutex_init(struct mutex *mtx, bool pshared)
/* In normal builds enable error checking, such as recursive usage. */
CHECK_ERR(pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK));
#endif
+ if (recursive)
+ CHECK_ERR(pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE));
if (pshared)
CHECK_ERR(pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED));
-
CHECK_ERR(pthread_mutex_init(&mtx->lock, &attr));
CHECK_ERR(pthread_mutexattr_destroy(&attr));
}
void mutex_init(struct mutex *mtx)
{
- __mutex_init(mtx, /*pshared=*/false);
+ __mutex_init(mtx, /*pshared=*/false, /*recursive=*/false);
}
void mutex_init_pshared(struct mutex *mtx)
{
- __mutex_init(mtx, /*pshared=*/true);
+ __mutex_init(mtx, /*pshared=*/true, /*recursive=*/false);
+}
+
+void mutex_init_recursive(struct mutex *mtx)
+{
+ __mutex_init(mtx, /*pshared=*/false, /*recursive=*/true);
}
void mutex_destroy(struct mutex *mtx)
diff --git a/tools/perf/util/mutex.h b/tools/perf/util/mutex.h
index 38458f00846f..70232d8d094f 100644
--- a/tools/perf/util/mutex.h
+++ b/tools/perf/util/mutex.h
@@ -104,6 +104,8 @@ void mutex_init(struct mutex *mtx);
* process-private attribute.
*/
void mutex_init_pshared(struct mutex *mtx);
+/* Initializes a mutex that may be recursively held on the same thread. */
+void mutex_init_recursive(struct mutex *mtx);
void mutex_destroy(struct mutex *mtx);
void mutex_lock(struct mutex *mtx) EXCLUSIVE_LOCK_FUNCTION(*mtx);
--
2.51.2.1041.gc1ab5b90ca-goog
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