From 834ebb5678d75d844f5d4f44ede78724d8c96630 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 24 Nov 2025 10:59:08 +0000 Subject: [PATCH] perf tools: Don't read build-ids from non-regular files Simplify the build ID reading code by removing the non-blocking option. Having to pass the correct option to this function was fragile and a mistake would result in a hang, see the linked fix. Furthermore, compressed files are always opened blocking anyway, ignoring the non-blocking option. We also don't expect to read build IDs from non-regular files. The only hits to this function that are non-regular are devices that won't be elf files with build IDs, for example "/dev/dri/renderD129". Now instead of opening these as non-blocking and failing to read, we skip them. Even if something like a pipe or character device did have a build ID, I don't think it would have worked because you need to call read() in a loop, check for -EAGAIN and handle timeouts to make non-blocking reads work. Link: https://lore.kernel.org/linux-perf-users/20251022-james-perf-fix-dso-block-v1-1-c4faab150546@linaro.org/ Signed-off-by: James Clark Signed-off-by: Namhyung Kim --- tools/perf/bench/inject-buildid.c | 2 +- tools/perf/builtin-buildid-cache.c | 8 ++++---- tools/perf/builtin-inject.c | 4 ++-- tools/perf/tests/pe-file-parsing.c | 4 ++-- tools/perf/tests/sdt.c | 2 +- tools/perf/util/build-id.c | 4 ++-- tools/perf/util/debuginfo.c | 2 +- tools/perf/util/dsos.c | 4 ++-- tools/perf/util/libbfd.c | 9 +++++++-- tools/perf/util/libbfd.h | 5 ++--- tools/perf/util/symbol-elf.c | 13 +++++++------ tools/perf/util/symbol-minimal.c | 11 ++++++++--- tools/perf/util/symbol.c | 5 ++--- tools/perf/util/symbol.h | 2 +- tools/perf/util/synthetic-events.c | 2 +- 15 files changed, 43 insertions(+), 34 deletions(-) diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c index 12387ea88b9a9..aad572a78d7fc 100644 --- a/tools/perf/bench/inject-buildid.c +++ b/tools/perf/bench/inject-buildid.c @@ -85,7 +85,7 @@ static int add_dso(const char *fpath, const struct stat *sb __maybe_unused, if (typeflag == FTW_D || typeflag == FTW_SL) return 0; - if (filename__read_build_id(fpath, &bid, /*block=*/true) < 0) + if (filename__read_build_id(fpath, &bid) < 0) return 0; dso->name = realpath(fpath, NULL); diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c index 2e0f2004696ae..c98104481c8a1 100644 --- a/tools/perf/builtin-buildid-cache.c +++ b/tools/perf/builtin-buildid-cache.c @@ -180,7 +180,7 @@ static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi) struct nscookie nsc; nsinfo__mountns_enter(nsi, &nsc); - err = filename__read_build_id(filename, &bid, /*block=*/true); + err = filename__read_build_id(filename, &bid); nsinfo__mountns_exit(&nsc); if (err < 0) { pr_debug("Couldn't read a build-id in %s\n", filename); @@ -204,7 +204,7 @@ static int build_id_cache__remove_file(const char *filename, struct nsinfo *nsi) int err; nsinfo__mountns_enter(nsi, &nsc); - err = filename__read_build_id(filename, &bid, /*block=*/true); + err = filename__read_build_id(filename, &bid); nsinfo__mountns_exit(&nsc); if (err < 0) { pr_debug("Couldn't read a build-id in %s\n", filename); @@ -280,7 +280,7 @@ static bool dso__missing_buildid_cache(struct dso *dso, int parm __maybe_unused) if (!dso__build_id_filename(dso, filename, sizeof(filename), false)) return true; - if (filename__read_build_id(filename, &bid, /*block=*/true) == -1) { + if (filename__read_build_id(filename, &bid) == -1) { if (errno == ENOENT) return false; @@ -309,7 +309,7 @@ static int build_id_cache__update_file(const char *filename, struct nsinfo *nsi) int err; nsinfo__mountns_enter(nsi, &nsc); - err = filename__read_build_id(filename, &bid, /*block=*/true); + err = filename__read_build_id(filename, &bid); nsinfo__mountns_exit(&nsc); if (err < 0) { pr_debug("Couldn't read a build-id in %s\n", filename); diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c index bd9245d2dd41a..0e40f2a4bd18b 100644 --- a/tools/perf/builtin-inject.c +++ b/tools/perf/builtin-inject.c @@ -668,12 +668,12 @@ static int dso__read_build_id(struct dso *dso) mutex_lock(dso__lock(dso)); nsinfo__mountns_enter(dso__nsinfo(dso), &nsc); - if (filename__read_build_id(dso__long_name(dso), &bid, /*block=*/true) > 0) + if (filename__read_build_id(dso__long_name(dso), &bid) > 0) dso__set_build_id(dso, &bid); else if (dso__nsinfo(dso)) { char *new_name = dso__filename_with_chroot(dso, dso__long_name(dso)); - if (new_name && filename__read_build_id(new_name, &bid, /*block=*/true) > 0) + if (new_name && filename__read_build_id(new_name, &bid) > 0) dso__set_build_id(dso, &bid); free(new_name); } diff --git a/tools/perf/tests/pe-file-parsing.c b/tools/perf/tests/pe-file-parsing.c index 8b31d1d05f905..30c7da79e109b 100644 --- a/tools/perf/tests/pe-file-parsing.c +++ b/tools/perf/tests/pe-file-parsing.c @@ -37,7 +37,7 @@ static int run_dir(const char *d) size_t idx; scnprintf(filename, PATH_MAX, "%s/pe-file.exe", d); - ret = filename__read_build_id(filename, &bid, /*block=*/true); + ret = filename__read_build_id(filename, &bid); TEST_ASSERT_VAL("Failed to read build_id", ret == sizeof(expect_build_id)); TEST_ASSERT_VAL("Wrong build_id", !memcmp(bid.data, expect_build_id, @@ -49,7 +49,7 @@ static int run_dir(const char *d) !strcmp(debuglink, expect_debuglink)); scnprintf(debugfile, PATH_MAX, "%s/%s", d, debuglink); - ret = filename__read_build_id(debugfile, &bid, /*block=*/true); + ret = filename__read_build_id(debugfile, &bid); TEST_ASSERT_VAL("Failed to read debug file build_id", ret == sizeof(expect_build_id)); TEST_ASSERT_VAL("Wrong build_id", !memcmp(bid.data, expect_build_id, diff --git a/tools/perf/tests/sdt.c b/tools/perf/tests/sdt.c index 6132f1af3e22d..93baee2eae42a 100644 --- a/tools/perf/tests/sdt.c +++ b/tools/perf/tests/sdt.c @@ -31,7 +31,7 @@ static int build_id_cache__add_file(const char *filename) struct build_id bid = { .size = 0, }; int err; - err = filename__read_build_id(filename, &bid, /*block=*/true); + err = filename__read_build_id(filename, &bid); if (err < 0) { pr_debug("Failed to read build id of %s\n", filename); return err; diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c index 35505a1ffd111..fdb35133fde43 100644 --- a/tools/perf/util/build-id.c +++ b/tools/perf/util/build-id.c @@ -122,7 +122,7 @@ int filename__snprintf_build_id(const char *pathname, char *sbuild_id, size_t sb struct build_id bid = { .size = 0, }; int ret; - ret = filename__read_build_id(pathname, &bid, /*block=*/true); + ret = filename__read_build_id(pathname, &bid); if (ret < 0) return ret; @@ -848,7 +848,7 @@ static int filename__read_build_id_ns(const char *filename, int ret; nsinfo__mountns_enter(nsi, &nsc); - ret = filename__read_build_id(filename, bid, /*block=*/true); + ret = filename__read_build_id(filename, bid); nsinfo__mountns_exit(&nsc); return ret; diff --git a/tools/perf/util/debuginfo.c b/tools/perf/util/debuginfo.c index bb9ebd84ec2d2..4a559b3e8cdce 100644 --- a/tools/perf/util/debuginfo.c +++ b/tools/perf/util/debuginfo.c @@ -115,7 +115,7 @@ struct debuginfo *debuginfo__new(const char *path) * incase the path isn't for a regular file. */ assert(!dso__has_build_id(dso)); - if (filename__read_build_id(path, &bid, /*block=*/false) > 0) + if (filename__read_build_id(path, &bid) > 0) dso__set_build_id(dso, &bid); for (type = distro_dwarf_types; diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c index 64c1d65b01496..0a7645c7fae7d 100644 --- a/tools/perf/util/dsos.c +++ b/tools/perf/util/dsos.c @@ -81,13 +81,13 @@ static int dsos__read_build_ids_cb(struct dso *dso, void *data) return 0; } nsinfo__mountns_enter(dso__nsinfo(dso), &nsc); - if (filename__read_build_id(dso__long_name(dso), &bid, /*block=*/true) > 0) { + if (filename__read_build_id(dso__long_name(dso), &bid) > 0) { dso__set_build_id(dso, &bid); args->have_build_id = true; } else if (errno == ENOENT && dso__nsinfo(dso)) { char *new_name = dso__filename_with_chroot(dso, dso__long_name(dso)); - if (new_name && filename__read_build_id(new_name, &bid, /*block=*/true) > 0) { + if (new_name && filename__read_build_id(new_name, &bid) > 0) { dso__set_build_id(dso, &bid); args->have_build_id = true; } diff --git a/tools/perf/util/libbfd.c b/tools/perf/util/libbfd.c index 01147fbf73b37..0099b415decca 100644 --- a/tools/perf/util/libbfd.c +++ b/tools/perf/util/libbfd.c @@ -383,13 +383,18 @@ out_close: return err; } -int libbfd__read_build_id(const char *filename, struct build_id *bid, bool block) +int libbfd__read_build_id(const char *filename, struct build_id *bid) { size_t size = sizeof(bid->data); int err = -1, fd; bfd *abfd; - fd = open(filename, block ? O_RDONLY : (O_RDONLY | O_NONBLOCK)); + if (!filename) + return -EFAULT; + if (!is_regular_file(filename)) + return -EWOULDBLOCK; + + fd = open(filename, O_RDONLY); if (fd < 0) return -1; diff --git a/tools/perf/util/libbfd.h b/tools/perf/util/libbfd.h index e300f171d1bd7..953886f3d62f3 100644 --- a/tools/perf/util/libbfd.h +++ b/tools/perf/util/libbfd.h @@ -25,7 +25,7 @@ void dso__free_a2l_libbfd(struct dso *dso); int symbol__disassemble_libbfd(const char *filename, struct symbol *sym, struct annotate_args *args); -int libbfd__read_build_id(const char *filename, struct build_id *bid, bool block); +int libbfd__read_build_id(const char *filename, struct build_id *bid); int libbfd_filename__read_debuglink(const char *filename, char *debuglink, size_t size); @@ -59,8 +59,7 @@ static inline int symbol__disassemble_libbfd(const char *filename __always_unuse } static inline int libbfd__read_build_id(const char *filename __always_unused, - struct build_id *bid __always_unused, - bool block __always_unused) + struct build_id *bid __always_unused) { return -1; } diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 9e820599bab38..c5c382c3409a7 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -860,20 +860,20 @@ out: return err; } -static int read_build_id(const char *filename, struct build_id *bid, bool block) +static int read_build_id(const char *filename, struct build_id *bid) { size_t size = sizeof(bid->data); int fd, err; Elf *elf; - err = libbfd__read_build_id(filename, bid, block); + err = libbfd__read_build_id(filename, bid); if (err >= 0) goto out; if (size < BUILD_ID_SIZE) goto out; - fd = open(filename, block ? O_RDONLY : (O_RDONLY | O_NONBLOCK)); + fd = open(filename, O_RDONLY); if (fd < 0) goto out; @@ -894,7 +894,7 @@ out: return err; } -int filename__read_build_id(const char *filename, struct build_id *bid, bool block) +int filename__read_build_id(const char *filename, struct build_id *bid) { struct kmod_path m = { .name = NULL, }; char path[PATH_MAX]; @@ -902,6 +902,8 @@ int filename__read_build_id(const char *filename, struct build_id *bid, bool blo if (!filename) return -EFAULT; + if (!is_regular_file(filename)) + return -EWOULDBLOCK; err = kmod_path__parse(&m, filename); if (err) @@ -918,10 +920,9 @@ int filename__read_build_id(const char *filename, struct build_id *bid, bool blo } close(fd); filename = path; - block = true; } - err = read_build_id(filename, bid, block); + err = read_build_id(filename, bid); if (m.comp) unlink(filename); diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c index aeb2532488953..c6b17c14a2e99 100644 --- a/tools/perf/util/symbol-minimal.c +++ b/tools/perf/util/symbol-minimal.c @@ -85,7 +85,7 @@ int filename__read_debuglink(const char *filename __maybe_unused, /* * Just try PT_NOTE header otherwise fails */ -int filename__read_build_id(const char *filename, struct build_id *bid, bool block) +int filename__read_build_id(const char *filename, struct build_id *bid) { int fd, ret = -1; bool need_swap = false, elf32; @@ -102,7 +102,12 @@ int filename__read_build_id(const char *filename, struct build_id *bid, bool blo void *phdr, *buf = NULL; ssize_t phdr_size, ehdr_size, buf_size = 0; - fd = open(filename, block ? O_RDONLY : (O_RDONLY | O_NONBLOCK)); + if (!filename) + return -EFAULT; + if (!is_regular_file(filename)) + return -EWOULDBLOCK; + + fd = open(filename, O_RDONLY); if (fd < 0) return -1; @@ -323,7 +328,7 @@ int dso__load_sym(struct dso *dso, struct map *map __maybe_unused, if (ret >= 0) RC_CHK_ACCESS(dso)->is_64_bit = ret; - if (filename__read_build_id(ss->name, &bid, /*block=*/true) > 0) + if (filename__read_build_id(ss->name, &bid) > 0) dso__set_build_id(dso, &bid); return 0; } diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index cc26b7bf302b2..d8fc5ea77f849 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -1743,14 +1743,13 @@ int dso__load(struct dso *dso, struct map *map) /* * Read the build id if possible. This is required for - * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work. Don't block in case path - * isn't for a regular file. + * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work. */ if (!dso__has_build_id(dso)) { struct build_id bid = { .size = 0, }; __symbol__join_symfs(name, PATH_MAX, dso__long_name(dso)); - if (filename__read_build_id(name, &bid, /*block=*/false) > 0) + if (filename__read_build_id(name, &bid) > 0) dso__set_build_id(dso, &bid); } diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h index 3471062187992..3fb5d146d9b15 100644 --- a/tools/perf/util/symbol.h +++ b/tools/perf/util/symbol.h @@ -140,7 +140,7 @@ struct symbol *dso__next_symbol(struct symbol *sym); enum dso_type dso__type_fd(int fd); -int filename__read_build_id(const char *filename, struct build_id *id, bool block); +int filename__read_build_id(const char *filename, struct build_id *id); int sysfs__read_build_id(const char *filename, struct build_id *bid); int modules__parse(const char *filename, void *arg, int (*process_module)(void *arg, const char *name, diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 5aa44c4aba625..2ba9fa25e00a6 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -401,7 +401,7 @@ static void perf_record_mmap2__read_build_id(struct perf_record_mmap2 *event, nsi = nsinfo__new(event->pid); nsinfo__mountns_enter(nsi, &nc); - rc = filename__read_build_id(event->filename, &bid, /*block=*/false) > 0 ? 0 : -1; + rc = filename__read_build_id(event->filename, &bid) > 0 ? 0 : -1; nsinfo__mountns_exit(&nc); nsinfo__put(nsi); -- 2.47.3