perf symbols: Call the symbol filter in dso__synthesize_plt_symbols()

We need to pass the symbol to the filter so that, for instance,
'perf top' can do filtering and also set the private area it
manages, setting the ->map pointer, etc.

I found this while running 'perf top' on a machine where hits
happened on PLT symbols, where ->map wasn't being set up and
segfaults thus happened.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1258386491-20278-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/util/symbol.c

@@ -281,6 +281,11 @@ static int kernel_maps__load_all_kallsyms(void)
 		if (sym == NULL)
 			goto out_delete_line;
 
+		/*
+		 * We will pass the symbols to the filter later, in
+		 * kernel_maps__split_kallsyms, when we have split the
+		 * maps per module
+		 */
 		dso__insert_symbol(kernel_map->dso, sym);
 	}
 
@@ -555,7 +560,8 @@ static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
  * And always look at the original dso, not at debuginfo packages, that
  * have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS).
  */
-static int dso__synthesize_plt_symbols(struct  dso *self)
+static int dso__synthesize_plt_symbols(struct  dso *self, struct map *map,
+				       symbol_filter_t filter)
 {
 	uint32_t nr_rel_entries, idx;
 	GElf_Sym sym;
@@ -643,8 +649,12 @@ static int dso__synthesize_plt_symbols(struct  dso *self)
 			if (!f)
 				goto out_elf_end;
 
-			dso__insert_symbol(self, f);
+			if (filter && filter(map, f))
-			++nr;
+				symbol__delete(f);
+			else {
+				dso__insert_symbol(self, f);
+				++nr;
+			}
 		}
 	} else if (shdr_rel_plt.sh_type == SHT_REL) {
 		GElf_Rel pos_mem, *pos;
@@ -661,8 +671,12 @@ static int dso__synthesize_plt_symbols(struct  dso *self)
 			if (!f)
 				goto out_elf_end;
 
-			dso__insert_symbol(self, f);
+			if (filter && filter(map, f))
-			++nr;
+				symbol__delete(f);
+			else {
+				dso__insert_symbol(self, f);
+				++nr;
+			}
 		}
 	}
 
@@ -1050,7 +1064,7 @@ compare_build_id:
 		goto more;
 
 	if (ret > 0) {
-		int nr_plt = dso__synthesize_plt_symbols(self);
+		int nr_plt = dso__synthesize_plt_symbols(self, map, filter);
 		if (nr_plt > 0)
 			ret += nr_plt;
 	}