From: Ian Rogers Date: Wed, 12 Nov 2025 07:43:11 +0000 (-0800) Subject: perf libbfd: Ensure libbfd is initialized prior to use X-Git-Tag: v6.18-rc6~1^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b72b8132d8fd2d6bf5b420a03d4fc553980c3a92;p=thirdparty%2Flinux.git 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. Committer testing: This happens only when building with 'make BUILD_NONDISTRO=1' and having the binutils-devel package (or equivalent) installed, i.e. linking with binutils devel files, an opt-in perf build. Before: root@x1:~# perf top perf: Segmentation fault -------- backtrace -------- root@x1:~# After this patch it works as before. Closes: https://lore.kernel.org/lkml/aQt66zhfxSA80xwt@gentoo.org/ Fixes: 95931d9a594dd0b5 ("perf libbfd: Move libbfd functionality to its own file") Reported-by: Guilherme Amadio Signed-off-by: Ian Rogers Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Signed-off-by: Arnaldo Carvalho de Melo --- 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);