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AJvYcCVy1Owl1nCisjV5bHLSpOk5NIO0IT1fKPhz0xJVlTzzW5WUU2cRWSvWl9jQNx7SF74XoN6gQqCy5vtD6+gsca2I@vger.kernel.org X-Gm-Message-State: AOJu0Yz4kHu4ldEM7gy/LzRKImsMGzh/5s0fY4wqVkD5aBoW6DTktret jBEyFcs9IUE8EM0Qob25xVbtbeAbwtcW3O29O9ztZavKOd+5FTuKQ6mOi/n3SDqEZGtLH1PaS/+ Kh/N+Zp5jig== X-Google-Smtp-Source: AGHT+IFYzbePgFT6fkcTqAR3CyIrUOSa1Z5mZa6Ca/+u8aQp6vZKodje8G+ZFlYCmO5NB1H0Ie4XbKA4XWxI X-Received: from dlzz38.prod.google.com ([2002:a05:7022:4a6:b0:11c:b3ab:7f07]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:ec3:b0:11b:9386:8255 with SMTP id a92af1059eb24-11c9d87a215mr30453528c88.42.1764622543976; Mon, 01 Dec 2025 12:55:43 -0800 (PST) Date: Mon, 1 Dec 2025 12:55:05 -0800 In-Reply-To: <20251201205509.195451-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251201205509.195451-1-irogers@google.com> X-Mailer: git-send-email 2.52.0.158.g65b55ccf14-goog Message-ID: <20251201205509.195451-7-irogers@google.com> Subject: [PATCH v2 06/10] perf symbol: Use fallbacks with filename__read_build_id From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Suzuki K Poulose , Mike Leach , James Clark , John Garry , Will Deacon , Leo Yan , Athira Rajeev , tanze , Stephen Brennan , Andi Kleen , Chun-Tse Shao , Thomas Falcon , Dapeng Mi , "Dr. David Alan Gilbert" , Christophe Leroy , "=?UTF-8?q?Krzysztof=20=C5=81opatowski?=" , "Masami Hiramatsu (Google)" , Alexandre Ghiti , Haibo Xu , Sergei Trofimovich , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Try libbfd, libelf and then symbol-minimal when trying to read a build ID. Always compile in symbol-minimal so that it is the fallback of last resort. Rename libelf reading code. Move the decompression code into symbol.c and allow its use with the symbol-minimal version. Signed-off-by: Ian Rogers --- tools/perf/util/Build | 5 +- tools/perf/util/libbfd.c | 9 +- tools/perf/util/libbfd.h | 5 +- tools/perf/util/perf-libelf.c | 113 ++++++++++++++++++++++ tools/perf/util/perf-libelf.h | 20 ++++ tools/perf/util/symbol-elf.c | 155 +------------------------------ tools/perf/util/symbol-minimal.c | 17 ++-- tools/perf/util/symbol-minimal.h | 9 ++ tools/perf/util/symbol.c | 52 +++++++++++ 9 files changed, 211 insertions(+), 174 deletions(-) create mode 100644 tools/perf/util/symbol-minimal.h diff --git a/tools/perf/util/Build b/tools/perf/util/Build index dcac6f1e1d99..c40053db2212 100644 --- a/tools/perf/util/Build +++ b/tools/perf/util/Build @@ -54,6 +54,7 @@ perf-util-y += usage.o perf-util-y += dso.o perf-util-y += dsos.o perf-util-y += symbol.o +perf-util-y += symbol-minimal.o perf-util-y += symbol_fprintf.o perf-util-y += map_symbol.o perf-util-y += color.o @@ -209,10 +210,6 @@ ifdef hashmap perf-util-y += hashmap.o endif -ifndef CONFIG_LIBELF -perf-util-y += symbol-minimal.o -endif - ifndef CONFIG_SETNS perf-util-y += setns.o endif diff --git a/tools/perf/util/libbfd.c b/tools/perf/util/libbfd.c index cc0c474cbfaa..c438fbd03b24 100644 --- a/tools/perf/util/libbfd.c +++ b/tools/perf/util/libbfd.c @@ -418,18 +418,13 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile) return err; } -int libbfd__read_build_id(const char *filename, struct build_id *bid) +int libbfd__read_build_id(int _fd, const char *filename, struct build_id *bid) { size_t size = sizeof(bid->data); int err = -1, fd; bfd *abfd; - if (!filename) - return -EFAULT; - if (!is_regular_file(filename)) - return -EWOULDBLOCK; - - fd = open(filename, O_RDONLY); + fd = dup(_fd); if (fd < 0) return -1; diff --git a/tools/perf/util/libbfd.h b/tools/perf/util/libbfd.h index 086c5f12cc34..72f1ad9a7578 100644 --- a/tools/perf/util/libbfd.h +++ b/tools/perf/util/libbfd.h @@ -26,7 +26,7 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile); 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); +int libbfd__read_build_id(int fd, const char *filename, struct build_id *bid); int libbfd_filename__read_debuglink(const char *filename, char *debuglink, size_t size); @@ -65,7 +65,8 @@ static inline int symbol__disassemble_libbfd(const char *filename __always_unuse return -1; } -static inline int libbfd__read_build_id(const char *filename __always_unused, +static inline int libbfd__read_build_id(int fd __always_unused, + const char *filename __always_unused, struct build_id *bid __always_unused) { return -1; diff --git a/tools/perf/util/perf-libelf.c b/tools/perf/util/perf-libelf.c index abd55bd7f14b..c7fa08a177d0 100644 --- a/tools/perf/util/perf-libelf.c +++ b/tools/perf/util/perf-libelf.c @@ -3,6 +3,10 @@ #include #include +#include + +#include "build-id.h" +#include "debug.h" Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep, GElf_Shdr *shp, const char *name, size_t *idx) @@ -30,3 +34,112 @@ Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep, return NULL; } +int __libelf__read_build_id(Elf *elf, void *bf, size_t size) +{ + int err = -1; + GElf_Ehdr ehdr; + GElf_Shdr shdr; + Elf_Data *data; + Elf_Scn *sec; + Elf_Kind ek; + void *ptr; + + if (size < BUILD_ID_SIZE) + goto out; + + ek = elf_kind(elf); + if (ek != ELF_K_ELF) + goto out; + + if (gelf_getehdr(elf, &ehdr) == NULL) { + pr_err("%s: cannot get elf header.\n", __func__); + goto out; + } + + /* + * Check following sections for notes: + * '.note.gnu.build-id' + * '.notes' + * '.note' (VDSO specific) + */ + do { + sec = elf_section_by_name(elf, &ehdr, &shdr, + ".note.gnu.build-id", NULL); + if (sec) + break; + + sec = elf_section_by_name(elf, &ehdr, &shdr, + ".notes", NULL); + if (sec) + break; + + sec = elf_section_by_name(elf, &ehdr, &shdr, + ".note", NULL); + if (sec) + break; + + return err; + + } while (0); + + data = elf_getdata(sec, NULL); + if (data == NULL) + goto out; + + ptr = data->d_buf; + while (ptr < (data->d_buf + data->d_size)) { + GElf_Nhdr *nhdr = ptr; + size_t namesz = NOTE_ALIGN(nhdr->n_namesz), + descsz = NOTE_ALIGN(nhdr->n_descsz); + const char *name; + + ptr += sizeof(*nhdr); + name = ptr; + ptr += namesz; + if (nhdr->n_type == NT_GNU_BUILD_ID && + nhdr->n_namesz == sizeof("GNU")) { + if (memcmp(name, "GNU", sizeof("GNU")) == 0) { + size_t sz = min(size, descsz); + + memcpy(bf, ptr, sz); + memset(bf + sz, 0, size - sz); + err = sz; + break; + } + } + ptr += descsz; + } + +out: + return err; +} + +int libelf__read_build_id(int _fd, const char *filename, struct build_id *bid) +{ + size_t size = sizeof(bid->data); + int fd, err = -1; + Elf *elf; + + if (size < BUILD_ID_SIZE) + goto out; + + fd = dup(_fd); + if (fd < 0) + goto out; + + elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); + if (elf == NULL) { + pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename); + goto out_close; + } + + err = __libelf__read_build_id(elf, bid->data, size); + if (err > 0) + bid->size = err; + + elf_end(elf); +out_close: + close(fd); +out: + return err; +} diff --git a/tools/perf/util/perf-libelf.h b/tools/perf/util/perf-libelf.h index 5d7d18daf5ff..931597493b1f 100644 --- a/tools/perf/util/perf-libelf.h +++ b/tools/perf/util/perf-libelf.h @@ -2,6 +2,8 @@ #ifndef __PERF_LIBELF_H #define __PERF_LIBELF_H +struct build_id; + #ifdef HAVE_LIBELF_SUPPORT #include @@ -17,9 +19,27 @@ # define PERF_ELF_C_READ_MMAP ELF_C_READ #endif +/* + * Align offset to 4 bytes as needed for note name and descriptor data. + */ +#define NOTE_ALIGN(n) (((n) + 3) & -4U) + Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep, GElf_Shdr *shp, const char *name, size_t *idx); +int __libelf__read_build_id(Elf *elf, void *bf, size_t size); + +int libelf__read_build_id(int _fd, const char *filename, struct build_id *bid); + +#else // !defined(HAVE_LIBELF_SUPPORT) + +static inline int libelf__read_build_id(int fd __always_unused, + const char *filename __always_unused, + struct build_id *bid __always_unused) +{ + return -1; +} + #endif // defined(HAVE_LIBELF_SUPPORT) #endif /* __PERF_LIBELF_H */ diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 72632bf9cc30..8fb7bf743ca6 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -751,159 +751,6 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) return 0; } -/* - * Align offset to 4 bytes as needed for note name and descriptor data. - */ -#define NOTE_ALIGN(n) (((n) + 3) & -4U) - -static int elf_read_build_id(Elf *elf, void *bf, size_t size) -{ - int err = -1; - GElf_Ehdr ehdr; - GElf_Shdr shdr; - Elf_Data *data; - Elf_Scn *sec; - Elf_Kind ek; - void *ptr; - - if (size < BUILD_ID_SIZE) - goto out; - - ek = elf_kind(elf); - if (ek != ELF_K_ELF) - goto out; - - if (gelf_getehdr(elf, &ehdr) == NULL) { - pr_err("%s: cannot get elf header.\n", __func__); - goto out; - } - - /* - * Check following sections for notes: - * '.note.gnu.build-id' - * '.notes' - * '.note' (VDSO specific) - */ - do { - sec = elf_section_by_name(elf, &ehdr, &shdr, - ".note.gnu.build-id", NULL); - if (sec) - break; - - sec = elf_section_by_name(elf, &ehdr, &shdr, - ".notes", NULL); - if (sec) - break; - - sec = elf_section_by_name(elf, &ehdr, &shdr, - ".note", NULL); - if (sec) - break; - - return err; - - } while (0); - - data = elf_getdata(sec, NULL); - if (data == NULL) - goto out; - - ptr = data->d_buf; - while (ptr < (data->d_buf + data->d_size)) { - GElf_Nhdr *nhdr = ptr; - size_t namesz = NOTE_ALIGN(nhdr->n_namesz), - descsz = NOTE_ALIGN(nhdr->n_descsz); - const char *name; - - ptr += sizeof(*nhdr); - name = ptr; - ptr += namesz; - if (nhdr->n_type == NT_GNU_BUILD_ID && - nhdr->n_namesz == sizeof("GNU")) { - if (memcmp(name, "GNU", sizeof("GNU")) == 0) { - size_t sz = min(size, descsz); - memcpy(bf, ptr, sz); - memset(bf + sz, 0, size - sz); - err = sz; - break; - } - } - ptr += descsz; - } - -out: - return err; -} - -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); - if (err >= 0) - goto out; - - if (size < BUILD_ID_SIZE) - goto out; - - fd = open(filename, O_RDONLY); - if (fd < 0) - goto out; - - elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); - if (elf == NULL) { - pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename); - goto out_close; - } - - err = elf_read_build_id(elf, bid->data, size); - if (err > 0) - bid->size = err; - - elf_end(elf); -out_close: - close(fd); -out: - return err; -} - -int filename__read_build_id(const char *filename, struct build_id *bid) -{ - struct kmod_path m = { .name = NULL, }; - char path[PATH_MAX]; - int err; - - if (!filename) - return -EFAULT; - if (!is_regular_file(filename)) - return -EWOULDBLOCK; - - err = kmod_path__parse(&m, filename); - if (err) - return -1; - - if (m.comp) { - int error = 0, fd; - - fd = filename__decompress(filename, path, sizeof(path), m.comp, &error); - if (fd < 0) { - pr_debug("Failed to decompress (error %d) %s\n", - error, filename); - return -1; - } - close(fd); - filename = path; - } - - err = read_build_id(filename, bid); - - if (m.comp) - unlink(filename); - return err; -} - int sysfs__read_build_id(const char *filename, struct build_id *bid) { size_t size = sizeof(bid->data); @@ -1171,7 +1018,7 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, struct build_id bid; int size; - size = elf_read_build_id(elf, build_id, BUILD_ID_SIZE); + size = __libelf__read_build_id(elf, build_id, BUILD_ID_SIZE); if (size <= 0) { *dso__load_errno(dso) = DSO_LOAD_ERRNO__CANNOT_READ_BUILDID; goto out_elf_end; diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c index c6b17c14a2e9..b71cf8caf282 100644 --- a/tools/perf/util/symbol-minimal.c +++ b/tools/perf/util/symbol-minimal.c @@ -1,5 +1,7 @@ +#include "debug.h" #include "dso.h" #include "symbol.h" +#include "symbol-minimal.h" #include "symsrc.h" #include @@ -75,17 +77,19 @@ static int read_build_id(void *note_data, size_t note_len, struct build_id *bid, return -1; } +#ifndef HAVE_LIBELF_SUPPORT int filename__read_debuglink(const char *filename __maybe_unused, char *debuglink __maybe_unused, size_t size __maybe_unused) { return -1; } +#endif /* * Just try PT_NOTE header otherwise fails */ -int filename__read_build_id(const char *filename, struct build_id *bid) +int sym_min__read_build_id(int _fd, const char *filename, struct build_id *bid) { int fd, ret = -1; bool need_swap = false, elf32; @@ -102,12 +106,7 @@ int filename__read_build_id(const char *filename, struct build_id *bid) void *phdr, *buf = NULL; ssize_t phdr_size, ehdr_size, buf_size = 0; - if (!filename) - return -EFAULT; - if (!is_regular_file(filename)) - return -EWOULDBLOCK; - - fd = open(filename, O_RDONLY); + fd = dup(_fd); if (fd < 0) return -1; @@ -199,9 +198,12 @@ int filename__read_build_id(const char *filename, struct build_id *bid) free(phdr); out: close(fd); + if (ret) + pr_debug("Error reading build-id from %s\n", filename); return ret; } +#ifndef HAVE_LIBELF_SUPPORT int sysfs__read_build_id(const char *filename, struct build_id *bid) { int fd; @@ -363,3 +365,4 @@ bool filename__has_section(const char *filename __maybe_unused, const char *sec { return false; } +#endif // HAVE_LIBELF_SUPPORT diff --git a/tools/perf/util/symbol-minimal.h b/tools/perf/util/symbol-minimal.h new file mode 100644 index 000000000000..185d98968212 --- /dev/null +++ b/tools/perf/util/symbol-minimal.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __PERF_SYMBOL_MINIMAL_H +#define __PERF_SYMBOL_MINIMAL_H + +struct build_id; + +int sym_min__read_build_id(int _fd, const char *filename, struct build_id *bid); + +#endif /* __PERF_SYMBOL_MINIMAL_H */ diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index f8c6a37464ca..8d461974a69f 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -35,6 +35,7 @@ #include "path.h" #include "perf-libelf.h" #include "strlist.h" +#include "symbol-minimal.h" #include "symbol.h" #include "symsrc.h" #include "util.h" // lsdir() @@ -1998,6 +1999,57 @@ static bool filename__readable(const char *file) return true; } +int filename__read_build_id(const char *filename, struct build_id *bid) +{ + struct kmod_path m = { .name = NULL, }; + char path[PATH_MAX]; + int err, fd; + + if (!filename) + return -EFAULT; + + if (!is_regular_file(filename)) + return -EWOULDBLOCK; + + err = kmod_path__parse(&m, filename); + if (err) + return -1; + + if (m.comp) { + int error = 0; + + fd = filename__decompress(filename, path, sizeof(path), m.comp, &error); + if (fd < 0) { + pr_debug("Failed to decompress (error %d) %s\n", + error, filename); + return -1; + } + lseek(fd, 0, SEEK_SET); + filename = path; + } else { + fd = open(filename, O_RDONLY); + if (fd < 0) { + pr_debug("Failed to open %s\n", filename); + return -1; + } + } + + err = libbfd__read_build_id(fd, filename, bid); + if (err == 0) + goto out; + + err = libelf__read_build_id(fd, filename, bid); + if (err == 0) + goto out; + + err = sym_min__read_build_id(fd, filename, bid); +out: + close(fd); + if (m.comp) + unlink(filename); + return err; +} + static char *dso__find_kallsyms(struct dso *dso, struct map *map) { struct build_id bid = { .size = 0, }; -- 2.52.0.158.g65b55ccf14-goog