Messages in this thread | | | Date | Fri, 31 Mar 2017 08:33:26 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH v2] Allow user probes on versioned symbols |
| |
On Thu, 30 Mar 2017 12:00:33 -0500 Paul Clarke <pc@us.ibm.com> wrote:
> Symbol versioning, as in glibc, results in symbols being defined as: > <real symbol>@[@]<version> > (Note that "@@" identifies a default symbol, in case 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) > -- > > The attached patch ignores versioning 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 > -- >
The wrapper function name may be concerned since "map__*" is usually used as a method for struct map. However, as c++ or other object-oriented langages support, I think this case is considered as a namespace(e.g. map::compare_symbol_names() ), since this comparation is applicable only for symbol name in map. I'm OK for this name.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Thank you,
> Signed-off-by: Paul A. Clarke <pc@us.ibm.com> > --- > Changes in 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/util/auxtrace.c | 2 +- > tools/perf/util/map.c | 21 +++++++++++++++++++++ > tools/perf/util/map.h | 3 ++- > tools/perf/util/symbol.c | 4 ++-- > 4 files changed, 26 insertions(+), 4 deletions(-) > > diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c > index c5a6e0b1..f3511a6 100644 > --- a/tools/perf/util/auxtrace.c > +++ b/tools/perf/util/auxtrace.c > @@ -1875,7 +1875,7 @@ static bool dso_sym_match(struct symbol *sym, const char *name, int *cnt, > int idx) > { > /* Same name, and global or the n'th found or any */ > - return !arch__compare_symbol_names(name, sym->name) && > + return !map__compare_symbol_names(name, sym->name) && > ((!idx && sym->binding == STB_GLOBAL) || > (idx > 0 && ++*cnt == idx) || > idx < 0); > diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c > index 4f9a71c..90342ee 100644 > --- a/tools/perf/util/map.c > +++ b/tools/perf/util/map.c > @@ -330,6 +330,27 @@ int __weak arch__compare_symbol_names(const char *namea, const char *nameb) > return strcmp(namea, nameb); > } > > +int map__compare_symbol_names(const char *namea, const char *nameb) > +{ > + int rc; > + const char *namea_versioning, *nameb_versioning; > + > + namea_versioning = strstr(namea,"@@"); > + if (namea_versioning) > + namea = strndup(namea,namea_versioning-namea); > + > + nameb_versioning = strstr(nameb,"@@"); > + if (nameb_versioning) > + nameb = strndup(nameb,nameb_versioning-nameb); > + > + rc = arch__compare_symbol_names(namea, nameb); > + > + if (namea_versioning) free((void *)namea); > + if (nameb_versioning) free((void *)nameb); > + > + return rc; > +} > + > 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 abdacf8..aaad64d 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 && map__compare_symbol_names(pos->name, sym_name) == 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); > +int map__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 dc93940..4fb9d275 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -411,7 +411,7 @@ 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 = map__compare_symbol_names(name, s->sym.name); > > if (cmp < 0) > n = n->rb_left; > @@ -429,7 +429,7 @@ static struct symbol *symbols__find_by_name(struct rb_root *symbols, > 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)) > + if (map__compare_symbol_names(tmp->sym.name, s->sym.name)) > break; > > s = tmp; > -- > 2.1.4 > > Regards, > Paul Clarke >
-- Masami Hiramatsu <mhiramat@kernel.org>
| |