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AJvYcCXWCfQSEwQpQhbJTfM9W0+V8vE56EKP9mbToQIBuAe9+Lkl1qJisQkb9kZeuDKjLU77cvsU7SePZ0oUDIk=@vger.kernel.org X-Gm-Message-State: AOJu0YwMc3cqAnEailgmQRjyI0G2AG5CFXVYsZsPQx7gsrQgsDChRjt6 lIAXiNe1f7N8yfM8668tEL/sSgeFqad+3wxRoioE12jjvkoV7dCykacwpcMMBXxWkXzksDiiF+C KluxKSkRCeQ== X-Google-Smtp-Source: AGHT+IFJk2oPW4r6McQs/nWZKohHl26TK542JQ9qyywVf6xez5/Uz4mzhA1OszwKINIzeSyPsG1Wz/ZjsSLx X-Received: from dlbvp8.prod.google.com ([2002:a05:7022:ff48:b0:11b:b1cd:e328]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:ea46:10b0:11b:9386:826d with SMTP id a92af1059eb24-11c9d8707d7mr4146724c88.42.1763865164339; Sat, 22 Nov 2025 18:32:44 -0800 (PST) Date: Sat, 22 Nov 2025 18:32:24 -0800 In-Reply-To: <20251123023225.8069-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251123023225.8069-1-irogers@google.com> X-Mailer: git-send-email 2.52.0.rc2.455.g230fcf2819-goog Message-ID: <20251123023225.8069-9-irogers@google.com> Subject: [PATCH v1 8/9] perf symbol: Use fallbacks for sysfs__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 , Aditya Bodkhe , 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-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Try libelf then symbol-minimal version in symbol.c. Reduce scope of NOTE_ALIGN macro. Signed-off-by: Ian Rogers --- tools/perf/util/perf-libelf.c | 56 ++++++++++++++++++++++++++++++++ tools/perf/util/perf-libelf.h | 12 ++++--- tools/perf/util/symbol-elf.c | 50 ---------------------------- tools/perf/util/symbol-minimal.c | 4 +-- tools/perf/util/symbol-minimal.h | 1 + tools/perf/util/symbol.c | 10 ++++++ 6 files changed, 76 insertions(+), 57 deletions(-) diff --git a/tools/perf/util/perf-libelf.c b/tools/perf/util/perf-libelf.c index a8a8c39056da..861cb7ae9b45 100644 --- a/tools/perf/util/perf-libelf.c +++ b/tools/perf/util/perf-libelf.c @@ -9,6 +9,11 @@ #include "build-id.h" #include "debug.h" =20 +/* + * 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) { @@ -145,6 +150,57 @@ int libelf__read_build_id(int _fd, const char *filenam= e, struct build_id *bid) return err; } =20 +int libelf_sysfs__read_build_id(const char *filename, struct build_id *bid) +{ + size_t size =3D sizeof(bid->data); + int fd, err =3D -1; + + fd =3D open(filename, O_RDONLY); + if (fd < 0) + goto out; + + while (1) { + char bf[BUFSIZ]; + GElf_Nhdr nhdr; + size_t namesz, descsz; + + if (read(fd, &nhdr, sizeof(nhdr)) !=3D sizeof(nhdr)) + break; + + namesz =3D NOTE_ALIGN(nhdr.n_namesz); + descsz =3D NOTE_ALIGN(nhdr.n_descsz); + if (nhdr.n_type =3D=3D NT_GNU_BUILD_ID && + nhdr.n_namesz =3D=3D sizeof("GNU")) { + if (read(fd, bf, namesz) !=3D (ssize_t)namesz) + break; + if (memcmp(bf, "GNU", sizeof("GNU")) =3D=3D 0) { + size_t sz =3D min(descsz, size); + + if (read(fd, bid->data, sz) =3D=3D (ssize_t)sz) { + memset(bid->data + sz, 0, size - sz); + bid->size =3D sz; + err =3D 0; + break; + } + } else if (read(fd, bf, descsz) !=3D (ssize_t)descsz) + break; + } else { + int n =3D namesz + descsz; + + if (n > (int)sizeof(bf)) { + n =3D sizeof(bf); + pr_debug("%s: truncating reading of build id in sysfs file %s: n_names= z=3D%u, n_descsz=3D%u.\n", + __func__, filename, nhdr.n_namesz, nhdr.n_descsz); + } + if (read(fd, bf, n) !=3D n) + break; + } + } + close(fd); +out: + return err; +} + int libelf_filename__read_debuglink(const char *filename, char *debuglink,= size_t size) { int fd, err =3D -1; diff --git a/tools/perf/util/perf-libelf.h b/tools/perf/util/perf-libelf.h index 167679f9fc9b..95fe8805aa41 100644 --- a/tools/perf/util/perf-libelf.h +++ b/tools/perf/util/perf-libelf.h @@ -21,17 +21,13 @@ struct build_id; # define PERF_ELF_C_READ_MMAP ELF_C_READ #endif =20 -/* - * 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, cons= t char *name, size_t *idx); =20 int __libelf__read_build_id(Elf *elf, void *bf, size_t size); =20 int libelf__read_build_id(int _fd, const char *filename, struct build_id *= bid); +int libelf_sysfs__read_build_id(const char *filename, struct build_id *bid= ); int libelf_filename__read_debuglink(const char *filename, char *debuglink,= size_t size); =20 #else // !defined(HAVE_LIBELF_SUPPORT) @@ -43,6 +39,12 @@ static inline int libelf__read_build_id(int fd __always_= unused, return -1; } =20 +static inline int libelf_sysfs__read_build_id(const char *filename __alway= s_unused, + struct build_id *bid __always_unused) +{ + return -1; +} + static inline int libelf_filename__read_debuglink(const char *filename __a= lways_unused, char *debuglink __always_unused, size_t size __always_unused) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index d4a1b01010c1..5ddf8353e01b 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -751,56 +751,6 @@ int dso__synthesize_plt_symbols(struct dso *dso, struc= t symsrc *ss) return 0; } =20 -int sysfs__read_build_id(const char *filename, struct build_id *bid) -{ - size_t size =3D sizeof(bid->data); - int fd, err =3D -1; - - fd =3D open(filename, O_RDONLY); - if (fd < 0) - goto out; - - while (1) { - char bf[BUFSIZ]; - GElf_Nhdr nhdr; - size_t namesz, descsz; - - if (read(fd, &nhdr, sizeof(nhdr)) !=3D sizeof(nhdr)) - break; - - namesz =3D NOTE_ALIGN(nhdr.n_namesz); - descsz =3D NOTE_ALIGN(nhdr.n_descsz); - if (nhdr.n_type =3D=3D NT_GNU_BUILD_ID && - nhdr.n_namesz =3D=3D sizeof("GNU")) { - if (read(fd, bf, namesz) !=3D (ssize_t)namesz) - break; - if (memcmp(bf, "GNU", sizeof("GNU")) =3D=3D 0) { - size_t sz =3D min(descsz, size); - if (read(fd, bid->data, sz) =3D=3D (ssize_t)sz) { - memset(bid->data + sz, 0, size - sz); - bid->size =3D sz; - err =3D 0; - break; - } - } else if (read(fd, bf, descsz) !=3D (ssize_t)descsz) - break; - } else { - int n =3D namesz + descsz; - - if (n > (int)sizeof(bf)) { - n =3D sizeof(bf); - pr_debug("%s: truncating reading of build id in sysfs file %s: n_names= z=3D%u, n_descsz=3D%u.\n", - __func__, filename, nhdr.n_namesz, nhdr.n_descsz); - } - if (read(fd, bf, n) !=3D n) - break; - } - } - close(fd); -out: - return err; -} - bool symsrc__possibly_runtime(struct symsrc *ss) { return ss->dynsym || ss->opdsec; diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-mini= mal.c index 8700c0628437..cc9055ba2f2a 100644 --- a/tools/perf/util/symbol-minimal.c +++ b/tools/perf/util/symbol-minimal.c @@ -194,8 +194,7 @@ int sym_min__read_build_id(int _fd, const char *filenam= e, struct build_id *bid) return ret; } =20 -#ifndef HAVE_LIBELF_SUPPORT -int sysfs__read_build_id(const char *filename, struct build_id *bid) +int sym_min_sysfs__read_build_id(const char *filename, struct build_id *bi= d) { int fd; int ret =3D -1; @@ -226,6 +225,7 @@ int sysfs__read_build_id(const char *filename, struct b= uild_id *bid) return ret; } =20 +#ifndef HAVE_LIBELF_SUPPORT int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, enum dso_binary_type type) { diff --git a/tools/perf/util/symbol-minimal.h b/tools/perf/util/symbol-mini= mal.h index 185d98968212..5cce1f1f0f16 100644 --- a/tools/perf/util/symbol-minimal.h +++ b/tools/perf/util/symbol-minimal.h @@ -5,5 +5,6 @@ struct build_id; =20 int sym_min__read_build_id(int _fd, const char *filename, struct build_id = *bid); +int sym_min_sysfs__read_build_id(const char *filename, struct build_id *bi= d); =20 #endif /* __PERF_SYMBOL_MINIMAL_H */ diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 1152d11a0366..81f4428f7bed 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -2049,6 +2049,16 @@ int filename__read_build_id(const char *filename, st= ruct build_id *bid, bool blo return err; } =20 +int sysfs__read_build_id(const char *filename, struct build_id *bid) +{ + int err =3D libelf_sysfs__read_build_id(filename, bid); + + if (err =3D=3D 0) + return 0; + + return sym_min_sysfs__read_build_id(filename, bid); +} + int filename__read_debuglink(const char *filename, char *debuglink, size_t= size) { int err =3D libbfd_filename__read_debuglink(filename, debuglink, size); --=20 2.52.0.rc2.455.g230fcf2819-goog