Messages in this thread | | | Subject | Re: [PATCH] perf symbols/KCORE: Rebuild rbtree when adjusting symbols for kcore | From | Adrian Hunter <> | Date | Thu, 12 Nov 2015 08:42:43 +0200 |
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On 11/11/15 22:44, Arnaldo Carvalho de Melo wrote: > Em Wed, Nov 11, 2015 at 03:02:35PM +0800, Wangnan (F) escreveu: >> >> >> On 2015/11/6 21:59, Adrian Hunter wrote: >>> On 06/11/15 15:19, Arnaldo Carvalho de Melo wrote: >>>> Em Fri, Nov 06, 2015 at 09:46:12AM +0000, Wang Nan escreveu: >>>>> In dso__split_kallsyms_for_kcore(), current code adjusts symbol's >>>>> address but only reinsert it into rbtree if the symbol belongs to >>>>> another map. However, the expression for adjusting symbol (pos->start -= >>>>> curr_map->start - curr_map->pgoff) can change the relative order between >>>>> two symbols (even if the affected symbols are in different maps, in >>>>> kcore case they are possible to share one same dso), which damages the >>>>> rbtree. >>>> Right, some code does change the symbol values it gets from whatever >>>> symtab (kallsyms, ELF, JIT maps, etc) when it should instead use the per >>>> map data structure (struct map) and its ->{map,unmap}_ip, ->pgoff, >>>> ->reloc, members for that :-\ >>>> >>>> I.e. 'struct dso' should be just what comes from the symtab, while >>>> 'struct map' should be about where that DSO is in memory. >>>> >>>> With that in mind, do you still think your fix is the correct one? >>>> >>>> Adrian? >>> The problem is when the order in memory (in kallsyms) is different >>> to the order on the dso (kcore). >>> >>> I think to make it more general it needs to insert to a new tree. >>> e.g. >>> >> >> I have tested this patch and it works for me. >> >> Thank you. > > Adrian, I took your explanation as the commit log, adding your S-o-B, so > far not provided, is that ok with you, can I have your S-o-B?
Yes. Thank you!
> >>From 500fe7dbd2c6cebc3638196352439490e1e3a8a4 Mon Sep 17 00:00:00 2001 > From: Adrian Hunter <adrian.hunter@intel.com> > Date: Fri, 6 Nov 2015 15:59:29 +0200 > Subject: [PATCH 1/1] perf symbols: Rebuild rbtree when adjusting symbols for > kcore > > Normally symbols are read from the DSO and adjusted, if need be, so that > the symbol start matches the file offset in the DSO file (we want the > file offset because that is what we know from MMAP events). That is done > by dso__load_sym() which inserts the symbols *after* adjusting them. > > In the case of kcore, the symbols have been read from kallsyms and the > symbol start is the memory address. The symbols have to be adjusted to > match the kcore file offsets. dso__split_kallsyms_for_kcore() does that, > but now the adjustment is being done *after* the symbols have been > inserted. It appears dso__split_kallsyms_for_kcore() was assuming that > changing the symbol start would not change the order in the rbtree - > which is, of course, not guaranteed. > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > Tested-by: Wang Nan <wangnan0@huawei.com> > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Zefan Li <lizefan@huawei.com> > Cc: pi3orama@163.com > Link: http://lkml.kernel.org/r/563CB241.2090701@intel.com > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> > --- > tools/perf/util/symbol.c | 30 ++++++++++++++---------------- > 1 file changed, 14 insertions(+), 16 deletions(-) > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > index b4cc7662677e..09343a880c0b 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -654,19 +654,24 @@ static int dso__split_kallsyms_for_kcore(struct dso *dso, struct map *map, > struct map_groups *kmaps = map__kmaps(map); > struct map *curr_map; > struct symbol *pos; > - int count = 0, moved = 0; > + int count = 0; > + struct rb_root old_root = dso->symbols[map->type]; > struct rb_root *root = &dso->symbols[map->type]; > struct rb_node *next = rb_first(root); > > if (!kmaps) > return -1; > > + *root = RB_ROOT; > + > while (next) { > char *module; > > pos = rb_entry(next, struct symbol, rb_node); > next = rb_next(&pos->rb_node); > > + rb_erase_init(&pos->rb_node, &old_root); > + > module = strchr(pos->name, '\t'); > if (module) > *module = '\0'; > @@ -674,28 +679,21 @@ static int dso__split_kallsyms_for_kcore(struct dso *dso, struct map *map, > curr_map = map_groups__find(kmaps, map->type, pos->start); > > if (!curr_map || (filter && filter(curr_map, pos))) { > - rb_erase_init(&pos->rb_node, root); > symbol__delete(pos); > - } else { > - pos->start -= curr_map->start - curr_map->pgoff; > - if (pos->end) > - pos->end -= curr_map->start - curr_map->pgoff; > - if (curr_map->dso != map->dso) { > - rb_erase_init(&pos->rb_node, root); > - symbols__insert( > - &curr_map->dso->symbols[curr_map->type], > - pos); > - ++moved; > - } else { > - ++count; > - } > + continue; > } > + > + pos->start -= curr_map->start - curr_map->pgoff; > + if (pos->end) > + pos->end -= curr_map->start - curr_map->pgoff; > + symbols__insert(&curr_map->dso->symbols[curr_map->type], pos); > + ++count; > } > > /* Symbols have been adjusted */ > dso->adjust_symbols = 1; > > - return count + moved; > + return count; > } > > /* >
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