From 18425f13a0890ac1e88a64276771c1ae10030b4a Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Tue, 24 Mar 2015 11:49:02 -0300 Subject: [PATCH] perf symbols: Save DSO loading errno to better report errors MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Before, when some problem happened while trying to load the kernel symtab, 'perf top' would show: ┌─Warning:───────────────────────────┐ │The vmlinux file can't be used. │ │Kernel samples will not be resolved.│ │ │ │ │ │Press any key... │ └────────────────────────────────────┘ Now, it reports: # perf top --vmlinux /dev/null ┌─Warning:───────────────────────────────────────────┐ │The /tmp/passwd file can't be used: Invalid ELF file│ │Kernel samples will not be resolved. │ │ │ │ │ │Press any key... │ └────────────────────────────────────────────────────┘ This is possible because we now register the reason for not being able to load the symtab in the dso->load_errno member, and provide a dso__strerror_load() routine to format this error into a strerror like string with a short reason for the error while loading. That can be just forwarding the dso__strerror_load() call to strerror_r(), or, for a separate errno range providing a custom message. Reported-by: Ingo Molnar Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Don Zickus Cc: Frederic Weisbecker Cc: Namhyung Kim Cc: Stephane Eranian Link: http://lkml.kernel.org/n/tip-u5rb5uq63xqhkfb8uv2lxd5u@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-top.c | 6 ++++-- tools/perf/util/dso.c | 33 ++++++++++++++++++++++++++++ tools/perf/util/dso.h | 28 ++++++++++++++++++++++++ tools/perf/util/symbol-elf.c | 37 +++++++++++++++++++++++--------- tools/perf/util/symbol-minimal.c | 7 +++--- 5 files changed, 96 insertions(+), 15 deletions(-) diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index 5fb8723c7128..1cb3436276d1 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -757,8 +757,10 @@ static void perf_event__process_sample(struct perf_tool *tool, al.map == machine->vmlinux_maps[MAP__FUNCTION] && RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION])) { if (symbol_conf.vmlinux_name) { - ui__warning("The %s file can't be used.\n%s", - symbol_conf.vmlinux_name, msg); + char serr[256]; + dso__strerror_load(al.map->dso, serr, sizeof(serr)); + ui__warning("The %s file can't be used: %s\n%s", + symbol_conf.vmlinux_name, serr, msg); } else { ui__warning("A vmlinux file was not found.\n%s", msg); diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c index 0d3667f92023..fc0ddd5792a9 100644 --- a/tools/perf/util/dso.c +++ b/tools/perf/util/dso.c @@ -1137,3 +1137,36 @@ enum dso_type dso__type(struct dso *dso, struct machine *machine) return dso__type_fd(fd); } + +int dso__strerror_load(struct dso *dso, char *buf, size_t buflen) +{ + int idx, errnum = dso->load_errno; + /* + * This must have a same ordering as the enum dso_load_errno. + */ + static const char *dso_load__error_str[] = { + "Internal tools/perf/ library error", + "Invalid ELF file", + "Can not read build id", + "Mismatching build id", + "Decompression failure", + }; + + BUG_ON(buflen == 0); + + if (errnum >= 0) { + const char *err = strerror_r(errnum, buf, buflen); + + if (err != buf) + scnprintf(buf, buflen, "%s", err); + + return 0; + } + + if (errnum < __DSO_LOAD_ERRNO__START || errnum >= __DSO_LOAD_ERRNO__END) + return -1; + + idx = errnum - __DSO_LOAD_ERRNO__START; + scnprintf(buf, buflen, "%s", dso_load__error_str[idx]); + return 0; +} diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h index 88f345cc5be2..e0901b4ed8de 100644 --- a/tools/perf/util/dso.h +++ b/tools/perf/util/dso.h @@ -60,6 +60,31 @@ enum dso_type { DSO__TYPE_X32BIT, }; +enum dso_load_errno { + DSO_LOAD_ERRNO__SUCCESS = 0, + + /* + * Choose an arbitrary negative big number not to clash with standard + * errno since SUS requires the errno has distinct positive values. + * See 'Issue 6' in the link below. + * + * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html + */ + __DSO_LOAD_ERRNO__START = -10000, + + DSO_LOAD_ERRNO__INTERNAL_ERROR = __DSO_LOAD_ERRNO__START, + + /* for symsrc__init() */ + DSO_LOAD_ERRNO__INVALID_ELF, + DSO_LOAD_ERRNO__CANNOT_READ_BUILDID, + DSO_LOAD_ERRNO__MISMATCHING_BUILDID, + + /* for decompress_kmodule */ + DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE, + + __DSO_LOAD_ERRNO__END, +}; + #define DSO__SWAP(dso, type, val) \ ({ \ type ____r = val; \ @@ -113,6 +138,7 @@ struct dso { enum dso_swap_type needs_swap; enum dso_binary_type symtab_type; enum dso_binary_type binary_type; + enum dso_load_errno load_errno; u8 adjust_symbols:1; u8 has_build_id:1; u8 has_srcline:1; @@ -294,4 +320,6 @@ void dso__free_a2l(struct dso *dso); enum dso_type dso__type(struct dso *dso, struct machine *machine); +int dso__strerror_load(struct dso *dso, char *buf, size_t buflen); + #endif /* __PERF_DSO */ diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 78ffde9df9bf..476268c99431 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -595,10 +595,13 @@ static int decompress_kmodule(struct dso *dso, const char *name, return -1; fd = mkstemp(tmpbuf); - if (fd < 0) + if (fd < 0) { + dso->load_errno = errno; goto out; + } if (!decompress_to_file(m.ext, name, fd)) { + dso->load_errno = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE; close(fd); fd = -1; } @@ -635,37 +638,49 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, Elf *elf; int fd; - if (dso__needs_decompress(dso)) + if (dso__needs_decompress(dso)) { fd = decompress_kmodule(dso, name, type); - else + if (fd < 0) + return -1; + } else { fd = open(name, O_RDONLY); - - if (fd < 0) - return -1; + if (fd < 0) { + dso->load_errno = errno; + return -1; + } + } elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); if (elf == NULL) { pr_debug("%s: cannot read %s ELF file.\n", __func__, name); + dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF; goto out_close; } if (gelf_getehdr(elf, &ehdr) == NULL) { + dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF; pr_debug("%s: cannot get elf header.\n", __func__); goto out_elf_end; } - if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) + if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) { + dso->load_errno = DSO_LOAD_ERRNO__INTERNAL_ERROR; goto out_elf_end; + } /* Always reject images with a mismatched build-id: */ if (dso->has_build_id) { u8 build_id[BUILD_ID_SIZE]; - if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0) + if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0) { + dso->load_errno = DSO_LOAD_ERRNO__CANNOT_READ_BUILDID; goto out_elf_end; + } - if (!dso__build_id_equal(dso, build_id)) + if (!dso__build_id_equal(dso, build_id)) { + dso->load_errno = DSO_LOAD_ERRNO__MISMATCHING_BUILDID; goto out_elf_end; + } } ss->is_64_bit = (gelf_getclass(elf) == ELFCLASS64); @@ -701,8 +716,10 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, } ss->name = strdup(name); - if (!ss->name) + if (!ss->name) { + dso->load_errno = errno; goto out_elf_end; + } ss->elf = elf; ss->fd = fd; diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c index d7efb03b3f9a..fd8477cacf88 100644 --- a/tools/perf/util/symbol-minimal.c +++ b/tools/perf/util/symbol-minimal.c @@ -246,13 +246,12 @@ out: return ret; } -int symsrc__init(struct symsrc *ss, struct dso *dso __maybe_unused, - const char *name, +int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, enum dso_binary_type type) { int fd = open(name, O_RDONLY); if (fd < 0) - return -1; + goto out_errno; ss->name = strdup(name); if (!ss->name) @@ -264,6 +263,8 @@ int symsrc__init(struct symsrc *ss, struct dso *dso __maybe_unused, return 0; out_close: close(fd); +out_errno: + dso->load_errno = errno; return -1; }