Messages in this thread Patch in this message | | | Date | Wed, 14 Jan 2015 10:54:17 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v2 3/4] perf probe: Do not rely on map__load() filter to find symbols |
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Em Wed, Jan 14, 2015 at 08:18:07PM +0900, Namhyung Kim escreveu: > The find_probe_trace_events_from_map() searches matching symbol from a > map (so from a backing dso). For uprobes, it'll create a new map (and > dso) and loads it using a filter. It's a little bit inefficient in that > it'll read out the symbol table everytime but works well anyway. > > For kprobes however, it'll reuse existing kernel map which might be > loaded before. In this case map__load() just returns with no result. > It makes kprobes always failed to find symbol even if it exists in the > map (dso). > > To fix it, use map__find_symbol_by_name() instead. It'll load a map > with full symbols and sorts them by name. It needs to search sibing > nodes since there can be multiple (local) symbols with same name. > > Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/util/probe-event.c | 32 +++++++++++++++----------------- > 1 file changed, 15 insertions(+), 17 deletions(-) > > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c > index 94a717bf007d..b1406d79b271 100644 > --- a/tools/perf/util/probe-event.c > +++ b/tools/perf/util/probe-event.c > @@ -2193,18 +2193,18 @@ static int __add_probe_trace_events(struct perf_probe_event *pev, > return ret; > } > > -static char *looking_function_name; > -static int num_matched_functions; > - > -static int probe_function_filter(struct map *map __maybe_unused, > - struct symbol *sym) > +static int find_probe_functions(struct map *map, char *name) > { > - if ((sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) && > - strcmp(looking_function_name, sym->name) == 0) { > - num_matched_functions++; > - return 0; > + struct symbol *sym, *link = NULL; > + int found = 0; > + > + while ((sym = map__find_symbol_by_name(map, name, NULL, link)) != NULL) { > + if (sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) > + found++; > + link = sym; > } > - return 1; > + > + return found; > }
How about using the "from" (that you called "link") to follow the list.h style and provide:
map__find_symbol_by_name_from(map, sym, filter, from);
And use it to implement map__find_symbol_by_name():
map__find_symbol_by_name(map, sym, filter) { return map__find_symbol_by_name_from(map, sym, filter, NULL); }
Your loop would then become:
link = NULL;
while ((sym = map__find_symbol_by_name_from(map, name, NULL, link)) != NULL) { if (sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) found++; link = sym; }
And no map__find_symbol_by_name() callsites would have to be touched.
- Arnaldo > #define strdup_or_goto(str, label) \ > @@ -2221,11 +2221,11 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev, > struct map *map = NULL; > struct kmap *kmap = NULL; > struct ref_reloc_sym *reloc_sym = NULL; > - struct symbol *sym; > - struct rb_node *nd; > + struct symbol *sym, *link = NULL; > struct probe_trace_event *tev; > struct perf_probe_point *pp = &pev->point; > struct probe_trace_point *tp; > + int num_matched_functions; > int ret, i; > > /* Init maps of given executable or kernel */ > @@ -2242,10 +2242,8 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev, > * Load matched symbols: Since the different local symbols may have > * same name but different addresses, this lists all the symbols. > */ > - num_matched_functions = 0; > - looking_function_name = pp->function; > - ret = map__load(map, probe_function_filter); > - if (ret || num_matched_functions == 0) { > + num_matched_functions = find_probe_functions(map, pp->function); > + if (num_matched_functions == 0) { > pr_err("Failed to find symbol %s in %s\n", pp->function, > target ? : "kernel"); > ret = -ENOENT; > @@ -2275,7 +2273,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev, > } > > ret = 0; > - map__for_each_symbol(map, sym, nd) { > + while ((sym = map__find_symbol_by_name(map, pp->function, NULL, link))) { > tev = (*tevs) + ret; > tp = &tev->point; > if (ret == num_matched_functions) { > -- > 2.2.1
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