Messages in this thread Patch in this message | | | Subject | Re: [PATCH] perf symbols/KCORE: Rebuild rbtree when adjusting symbols for kcore | From | Adrian Hunter <> | Date | Fri, 6 Nov 2015 15:59:29 +0200 |
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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.
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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