Messages in this thread Patch in this message | | | From | Paul Clarke <> | Subject | [PATCH v4] tools/perf: Allow user probes on versioned symbols | Date | Wed, 5 Apr 2017 22:30:03 -0500 |
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Symbol versioning, as in glibc, results in symbols being defined as: <real symbol>@[@]<version> (Note that "@@" identifies a default symbol, if the symbol name is repeated.)
perf is currently unable to deal with this, and is unable to create user probes at such symbols: -- $ nm /lib/powerpc64le-linux-gnu/libpthread.so.0 | grep pthread_create 0000000000008d30 t __pthread_create_2_1 0000000000008d30 T pthread_create@@GLIBC_2.17 $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create probe-definition(0): pthread_create symbol:pthread_create file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Open Debuginfo file: /usr/lib/debug/lib/powerpc64le-linux-gnu/libpthread-2.19.so Try to find probe point from debuginfo. Probe point 'pthread_create' not found. Error: Failed to add events. Reason: No such file or directory (Code: -2) --
One is not able to specify the fully versioned symbol, either, due to syntactic conflicts with other uses of "@" by perf: -- $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create@@GLIBC_2.17 probe-definition(0): pthread_create@@GLIBC_2.17 Semantic error :SRC@SRC is not allowed. 0 arguments Error: Command Parse Error. Reason: Invalid argument (Code: -22) --
This patch ignores the versioning tag for default symbols, thus allowing probes to be created for these symbols: -- $ /usr/bin/sudo ./perf probe -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create Added new event: probe_libpthread:pthread_create (on pthread_create in /lib/powerpc64le-linux-gnu/libpthread-2.19.so)
You can now use it in all perf tools, such as:
perf record -e probe_libpthread:pthread_create -aR sleep 1
$ /usr/bin/sudo ./perf record -e probe_libpthread:pthread_create -aR ./test 2 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.052 MB perf.data (2 samples) ] $ /usr/bin/sudo ./perf script test 2915 [000] 19124.260729: probe_libpthread:pthread_create: (3fff99248d38) test 2916 [000] 19124.260962: probe_libpthread:pthread_create: (3fff99248d38) $ /usr/bin/sudo ./perf probe --del=probe_libpthread:pthread_create Removed event: probe_libpthread:pthread_create --
Signed-off-by: Paul A. Clarke <pc@us.ibm.com> --- v4: - rebased to acme/perf/core - moved changes from "map" namespace to "symbol" namespace, - rewrote symbol__compare (now *match) to avoid need for strdup - new symbol__match_symbol_name to support versioned symbols, ignoring default tags - new arch__compare_symbol_names_n to map to strncmp - dso__find_symbol_by_name: now tries exact match (as before), then tries also adding symbols tagged as default (@@) - symbols__find_by_name: new parameter to support finding with or without default tags - does NOT handle setting probes using the tagged symbol name (symbol@[@]tag)
v3: - code style fixes per David Ahern
v2: - move logic from arch__compare_symbol_names to new map__compare_symbol_names - call through from map__compare_symbol_names to arch__compare_symbol_names - redirect uses of arch__compare_symbol_names - send patch to LKML tools/perf/arch/powerpc/util/sym-handling.c | 12 ++++++ tools/perf/util/map.c | 5 --- tools/perf/util/map.h | 5 ++- tools/perf/util/symbol.c | 62 +++++++++++++++++++++++------ tools/perf/util/symbol.h | 9 +++++ 5 files changed, 73 insertions(+), 20 deletions(-)
diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c index 39dbe51..0d40e17 100644 --- a/tools/perf/arch/powerpc/util/sym-handling.c +++ b/tools/perf/arch/powerpc/util/sym-handling.c @@ -52,6 +52,18 @@ int arch__compare_symbol_names(const char *namea, const char *nameb) return strcmp(namea, nameb); } + +int arch__compare_symbol_names_n(const char *namea, const char *nameb, + unsigned int n) +{ + /* Skip over initial dot */ + if (*namea == '.') + namea++; + if (*nameb == '.') + nameb++; + + return strncmp(namea, nameb, n); +} #endif #if defined(_CALL_ELF) && _CALL_ELF == 2 diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c index c1870ac..f4d8272 100644 --- a/tools/perf/util/map.c +++ b/tools/perf/util/map.c @@ -325,11 +325,6 @@ int map__load(struct map *map) return 0; } -int __weak arch__compare_symbol_names(const char *namea, const char *nameb) -{ - return strcmp(namea, nameb); -} - struct symbol *map__find_symbol(struct map *map, u64 addr) { if (map__load(map) < 0) diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h index c8a5a64..325bbc8 100644 --- a/tools/perf/util/map.h +++ b/tools/perf/util/map.h @@ -130,13 +130,14 @@ struct thread; */ #define __map__for_each_symbol_by_name(map, sym_name, pos) \ for (pos = map__find_symbol_by_name(map, sym_name); \ - pos && arch__compare_symbol_names(pos->name, sym_name) == 0; \ + pos && \ + symbol__match_symbol_name(pos->name, sym_name, \ + SYMBOLS__TAG_INCLUDE_DEFAULT_ONLY) == 0; \ pos = symbol__next_by_name(pos)) #define map__for_each_symbol_by_name(map, sym_name, pos) \ __map__for_each_symbol_by_name(map, sym_name, (pos)) -int arch__compare_symbol_names(const char *namea, const char *nameb); void map__init(struct map *map, enum map_type type, u64 start, u64 end, u64 pgoff, struct dso *dso); struct map *map__new(struct machine *machine, u64 start, u64 len, diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 9b4d8ba..c29440d 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -87,6 +87,17 @@ static int prefix_underscores_count(const char *str) return tail - str; } +int __weak arch__compare_symbol_names(const char *namea, const char *nameb) +{ + return strcmp(namea, nameb); +} + +int __weak arch__compare_symbol_names_n(const char *namea, const char *nameb, + unsigned int n) +{ + return strncmp(namea, nameb, n); +} + int __weak arch__choose_best_symbol(struct symbol *syma, struct symbol *symb __maybe_unused) { @@ -396,8 +407,26 @@ static void symbols__sort_by_name(struct rb_root *symbols, } } +int symbol__match_symbol_name(const char *name, const char *str, + int including_tags) +{ + const char *versioning; + + if (including_tags == SYMBOLS__TAG_INCLUDE_DEFAULT_ONLY && + (versioning = strstr(name,"@@"))) { + + unsigned int len = strlen(str); + if (len < versioning - name) + len = versioning - name; + + return arch__compare_symbol_names_n(name, str, len); + } else + return arch__compare_symbol_names(name, str); +} + static struct symbol *symbols__find_by_name(struct rb_root *symbols, - const char *name) + const char *name, + unsigned int including_tags) { struct rb_node *n; struct symbol_name_rb_node *s = NULL; @@ -411,11 +440,12 @@ static struct symbol *symbols__find_by_name(struct rb_root *symbols, int cmp; s = rb_entry(n, struct symbol_name_rb_node, rb_node); - cmp = arch__compare_symbol_names(name, s->sym.name); + cmp = symbol__match_symbol_name(s->sym.name, name, + including_tags); - if (cmp < 0) + if (cmp > 0) n = n->rb_left; - else if (cmp > 0) + else if (cmp < 0) n = n->rb_right; else break; @@ -424,16 +454,17 @@ static struct symbol *symbols__find_by_name(struct rb_root *symbols, if (n == NULL) return NULL; - /* return first symbol that has same name (if any) */ - for (n = rb_prev(n); n; n = rb_prev(n)) { - struct symbol_name_rb_node *tmp; + if (including_tags != SYMBOLS__TAG_INCLUDE_DEFAULT_ONLY) + /* return first symbol that has same name (if any) */ + for (n = rb_prev(n); n; n = rb_prev(n)) { + struct symbol_name_rb_node *tmp; - tmp = rb_entry(n, struct symbol_name_rb_node, rb_node); - if (arch__compare_symbol_names(tmp->sym.name, s->sym.name)) - break; + tmp = rb_entry(n, struct symbol_name_rb_node, rb_node); + if (arch__compare_symbol_names(tmp->sym.name, s->sym.name)) + break; - s = tmp; - } + s = tmp; + } return &s->sym; } @@ -500,7 +531,12 @@ struct symbol *symbol__next_by_name(struct symbol *sym) struct symbol *dso__find_symbol_by_name(struct dso *dso, enum map_type type, const char *name) { - return symbols__find_by_name(&dso->symbol_names[type], name); + struct symbol *s = symbols__find_by_name(&dso->symbol_names[type], name, + SYMBOLS__TAG_INCLUDE_NONE); + if (!s) + s = symbols__find_by_name(&dso->symbol_names[type], name, + SYMBOLS__TAG_INCLUDE_DEFAULT_ONLY); + return s; } void dso__sort_by_name(struct dso *dso, enum map_type type) diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h index 5245d2f..bde2100 100644 --- a/tools/perf/util/symbol.h +++ b/tools/perf/util/symbol.h @@ -348,8 +348,17 @@ void arch__sym_update(struct symbol *s, GElf_Sym *sym); #define SYMBOL_A 0 #define SYMBOL_B 1 +int arch__compare_symbol_names(const char *namea, const char *nameb); +int arch__compare_symbol_names_n(const char *namea, const char *nameb, + unsigned int n); int arch__choose_best_symbol(struct symbol *syma, struct symbol *symb); +#define SYMBOLS__TAG_INCLUDE_NONE 0 +#define SYMBOLS__TAG_INCLUDE_DEFAULT_ONLY 1 + +int symbol__match_symbol_name(const char *namea, const char *nameb, + int including_tags); + /* structure containing an SDT note's info */ struct sdt_note { char *name; /* name of the note*/ -- 2.1.4 Regards, PC
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