Rather than have 2 Dwfl unify the Dwfl in skip-callchain-idx with that is used by libdw__addr2line. Rename that variable in struct dso from a2l_libdw to just libdw as it is now used in more than addr2line.
The Dwfl in skip-callchain-idx uses a map address when being read with dwfl_report_elf (rather than dwfl_report_offline that addr2line uses). skip-callchain-idx is wrong as the map address can vary between processes because of ASLR, ie it should need a different Dwfl per process. In the code after this patch the base address becomes 0 and the mapped PC is used with the dwfl functions. This should increase the accuracy of skip-callchain-idx, but the impact has only been build tested. Signed-off-by: Ian Rogers <[email protected]> --- .../arch/powerpc/util/skip-callchain-idx.c | 52 ++------- tools/perf/util/dso.c | 2 +- tools/perf/util/dso.h | 23 ++-- tools/perf/util/libdw.c | 101 ++++++++++-------- tools/perf/util/libdw.h | 12 +-- tools/perf/util/srcline.c | 2 +- 6 files changed, 89 insertions(+), 103 deletions(-) diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c index 356786432fd3..e57f10798fa6 100644 --- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c +++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c @@ -30,14 +30,6 @@ * The libdwfl code in this file is based on code from elfutils * (libdwfl/argp-std.c, libdwfl/tests/addrcfi.c, etc). */ -static char *debuginfo_path; - -static const Dwfl_Callbacks offline_callbacks = { - .debuginfo_path = &debuginfo_path, - .find_debuginfo = dwfl_standard_find_debuginfo, - .section_address = dwfl_offline_section_address, -}; - /* * Use the DWARF expression for the Call-frame-address and determine @@ -149,44 +141,22 @@ static Dwarf_Frame *get_dwarf_frame(Dwfl_Module *mod, Dwarf_Addr pc) * yet used) * -1 in case of errors */ -static int check_return_addr(struct dso *dso, u64 map_start, Dwarf_Addr pc) +static int check_return_addr(struct dso *dso, Dwarf_Addr mapped_pc) { int rc = -1; Dwfl *dwfl; Dwfl_Module *mod; Dwarf_Frame *frame; int ra_regno; - Dwarf_Addr start = pc; - Dwarf_Addr end = pc; + Dwarf_Addr start = mapped_pc; + Dwarf_Addr end = mapped_pc; bool signalp; - const char *exec_file = dso__long_name(dso); - - dwfl = RC_CHK_ACCESS(dso)->dwfl; - - if (!dwfl) { - dwfl = dwfl_begin(&offline_callbacks); - if (!dwfl) { - pr_debug("dwfl_begin() failed: %s\n", dwarf_errmsg(-1)); - return -1; - } - - mod = dwfl_report_elf(dwfl, exec_file, exec_file, -1, - map_start, false); - if (!mod) { - pr_debug("dwfl_report_elf() failed %s\n", - dwarf_errmsg(-1)); - /* - * We normally cache the DWARF debug info and never - * call dwfl_end(). But to prevent fd leak, free in - * case of error. - */ - dwfl_end(dwfl); - goto out; - } - RC_CHK_ACCESS(dso)->dwfl = dwfl; - } - mod = dwfl_addrmodule(dwfl, pc); + dwfl = dso__libdw_dwfl(dso); + if (!dwfl) + return -1; + + mod = dwfl_addrmodule(dwfl, mapped_pc); if (!mod) { pr_debug("dwfl_addrmodule() failed, %s\n", dwarf_errmsg(-1)); goto out; @@ -196,9 +166,9 @@ static int check_return_addr(struct dso *dso, u64 map_start, Dwarf_Addr pc) * To work with split debug info files (eg: glibc), check both * .eh_frame and .debug_frame sections of the ELF header. */ - frame = get_eh_frame(mod, pc); + frame = get_eh_frame(mod, mapped_pc); if (!frame) { - frame = get_dwarf_frame(mod, pc); + frame = get_dwarf_frame(mod, mapped_pc); if (!frame) goto out; } @@ -264,7 +234,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain) return skip_slot; } - rc = check_return_addr(dso, map__start(al.map), ip); + rc = check_return_addr(dso, map__map_ip(al.map, ip)); pr_debug("[DSO %s, sym %s, ip 0x%" PRIx64 "] rc %d\n", dso__long_name(dso), al.sym->name, ip, rc); diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c index 143720d1ecb1..dce207c7f862 100644 --- a/tools/perf/util/dso.c +++ b/tools/perf/util/dso.c @@ -1612,7 +1612,7 @@ void dso__delete(struct dso *dso) auxtrace_cache__free(RC_CHK_ACCESS(dso)->auxtrace_cache); dso_cache__free(dso); dso__free_a2l(dso); - dso__free_a2l_libdw(dso); + dso__free_libdw(dso); dso__free_symsrc_filename(dso); nsinfo__zput(RC_CHK_ACCESS(dso)->nsinfo); mutex_destroy(dso__lock(dso)); diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h index 4aee23775054..295388085031 100644 --- a/tools/perf/util/dso.h +++ b/tools/perf/util/dso.h @@ -268,11 +268,8 @@ DECLARE_RC_STRUCT(dso) { const char *short_name; const char *long_name; void *a2l; - void *a2l_libdw; + void *libdw; char *symsrc_filename; -#if defined(__powerpc__) - void *dwfl; /* DWARF debug info */ -#endif struct nsinfo *nsinfo; struct auxtrace_cache *auxtrace_cache; union { /* Tool specific area */ @@ -335,16 +332,26 @@ static inline void dso__set_a2l(struct dso *dso, void *val) RC_CHK_ACCESS(dso)->a2l = val; } -static inline void *dso__a2l_libdw(const struct dso *dso) +static inline void *dso__libdw(const struct dso *dso) { - return RC_CHK_ACCESS(dso)->a2l_libdw; + return RC_CHK_ACCESS(dso)->libdw; } -static inline void dso__set_a2l_libdw(struct dso *dso, void *val) +static inline void dso__set_libdw(struct dso *dso, void *val) { - RC_CHK_ACCESS(dso)->a2l_libdw = val; + RC_CHK_ACCESS(dso)->libdw = val; } +struct Dwfl; +#ifdef HAVE_LIBDW_SUPPORT +struct Dwfl *dso__libdw_dwfl(struct dso *dso); +#else +static inline struct Dwfl *dso__libdw_dwfl(struct dso *dso __maybe_unused) +{ + return NULL; +} +#endif + static inline unsigned int dso__a2l_fails(const struct dso *dso) { return RC_CHK_ACCESS(dso)->a2l_fails; diff --git a/tools/perf/util/libdw.c b/tools/perf/util/libdw.c index b96c4e0d728f..216977884103 100644 --- a/tools/perf/util/libdw.c +++ b/tools/perf/util/libdw.c @@ -8,14 +8,62 @@ #include <unistd.h> #include <elfutils/libdwfl.h> -void dso__free_a2l_libdw(struct dso *dso) +static const Dwfl_Callbacks offline_callbacks = { + .find_debuginfo = dwfl_standard_find_debuginfo, + .section_address = dwfl_offline_section_address, + .find_elf = dwfl_build_id_find_elf, +}; + +void dso__free_libdw(struct dso *dso) { - Dwfl *dwfl = dso__a2l_libdw(dso); + Dwfl *dwfl = dso__libdw(dso); if (dwfl) { dwfl_end(dwfl); - dso__set_a2l_libdw(dso, NULL); + dso__set_libdw(dso, NULL); + } +} + +struct Dwfl *dso__libdw_dwfl(struct dso *dso) +{ + Dwfl *dwfl = dso__libdw(dso); + const char *dso_name; + Dwfl_Module *mod; + int fd; + + if (dwfl) + return dwfl; + + dso_name = dso__long_name(dso); + /* + * Initialize Dwfl session. + * We need to open the DSO file to report it to libdw. + */ + fd = open(dso_name, O_RDONLY); + if (fd < 0) + return NULL; + + dwfl = dwfl_begin(&offline_callbacks); + if (!dwfl) { + close(fd); + return NULL; + } + + /* + * If the report is successful, the file descriptor fd is consumed + * and closed by the Dwfl. If not, it is not closed. + */ + mod = dwfl_report_offline(dwfl, dso_name, dso_name, fd); + if (!mod) { + dwfl_end(dwfl); + close(fd); + return NULL; } + + dwfl_report_end(dwfl, /*removed=*/NULL, /*arg=*/NULL); + dso__set_libdw(dso, dwfl); + + return dwfl; } struct libdw_a2l_cb_args { @@ -63,58 +111,21 @@ static int libdw_a2l_cb(Dwarf_Die *die, void *_args) return 0; } -int libdw__addr2line(const char *dso_name, u64 addr, - char **file, unsigned int *line_nr, +int libdw__addr2line(u64 addr, char **file, unsigned int *line_nr, struct dso *dso, bool unwind_inlines, struct inline_node *node, struct symbol *sym) { - static const Dwfl_Callbacks offline_callbacks = { - .find_debuginfo = dwfl_standard_find_debuginfo, - .section_address = dwfl_offline_section_address, - .find_elf = dwfl_build_id_find_elf, - }; - Dwfl *dwfl = dso__a2l_libdw(dso); + Dwfl *dwfl = dso__libdw_dwfl(dso); Dwfl_Module *mod; Dwfl_Line *dwline; Dwarf_Addr bias; const char *src; int lineno = 0; - if (!dwfl) { - /* - * Initialize Dwfl session. - * We need to open the DSO file to report it to libdw. - */ - int fd; - - fd = open(dso_name, O_RDONLY); - if (fd < 0) - return 0; - - dwfl = dwfl_begin(&offline_callbacks); - if (!dwfl) { - close(fd); - return 0; - } - - /* - * If the report is successful, the file descriptor fd is consumed - * and closed by the Dwfl. If not, it is not closed. - */ - mod = dwfl_report_offline(dwfl, dso_name, dso_name, fd); - if (!mod) { - dwfl_end(dwfl); - close(fd); - return 0; - } - - dwfl_report_end(dwfl, /*removed=*/NULL, /*arg=*/NULL); - dso__set_a2l_libdw(dso, dwfl); - } else { - /* Dwfl session already initialized, get module for address. */ - mod = dwfl_addrmodule(dwfl, addr); - } + if (!dwfl) + return 0; + mod = dwfl_addrmodule(dwfl, addr); if (!mod) return 0; diff --git a/tools/perf/util/libdw.h b/tools/perf/util/libdw.h index 0f8d7b4a11a5..b12094737415 100644 --- a/tools/perf/util/libdw.h +++ b/tools/perf/util/libdw.h @@ -11,7 +11,6 @@ struct symbol; #ifdef HAVE_LIBDW_SUPPORT /* * libdw__addr2line - Convert address to source location using libdw - * @dso_name: Name of the DSO * @addr: Address to resolve * @file: Pointer to return filename (caller must free) * @line_nr: Pointer to return line number @@ -26,23 +25,22 @@ struct symbol; * * Returns 1 on success (found), 0 on failure (not found). */ -int libdw__addr2line(const char *dso_name, u64 addr, char **file, +int libdw__addr2line(u64 addr, char **file, unsigned int *line_nr, struct dso *dso, bool unwind_inlines, struct inline_node *node, struct symbol *sym); /* - * dso__free_a2l_libdw - Free libdw resources associated with the DSO + * dso__free_libdw - Free libdw resources associated with the DSO * @dso: The dso to free resources for * * This function cleans up the Dwfl context used for addr2line lookups. */ -void dso__free_a2l_libdw(struct dso *dso); +void dso__free_libdw(struct dso *dso); #else /* HAVE_LIBDW_SUPPORT */ -static inline int libdw__addr2line(const char *dso_name __maybe_unused, - u64 addr __maybe_unused, char **file __maybe_unused, +static inline int libdw__addr2line(u64 addr __maybe_unused, char **file __maybe_unused, unsigned int *line_nr __maybe_unused, struct dso *dso __maybe_unused, bool unwind_inlines __maybe_unused, @@ -52,7 +50,7 @@ static inline int libdw__addr2line(const char *dso_name __maybe_unused, return 0; } -static inline void dso__free_a2l_libdw(struct dso *dso __maybe_unused) +static inline void dso__free_libdw(struct dso *dso __maybe_unused) { } #endif /* HAVE_LIBDW_SUPPORT */ diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c index 28fa1abd1fd3..9be42f398440 100644 --- a/tools/perf/util/srcline.c +++ b/tools/perf/util/srcline.c @@ -161,7 +161,7 @@ static int addr2line(const char *dso_name, u64 addr, char **file, unsigned int * for (size_t i = 0; i < ARRAY_SIZE(symbol_conf.addr2line_style); i++) { switch (symbol_conf.addr2line_style[i]) { case A2L_STYLE_LIBDW: - ret = libdw__addr2line(dso_name, addr, file, line_nr, dso, unwind_inlines, + ret = libdw__addr2line(addr, file, line_nr, dso, unwind_inlines, node, sym); break; case A2L_STYLE_LLVM: -- 2.52.0.457.g6b5491de43-goog
