perf symbols: Do lazy symtab loading for the kernel & modules too

Just like we do with the other DSOs. This also simplifies the
kernel_maps setup process, now all that the tools need to do is
to call kernel_maps__init and the maps for the modules and
kernel will be created, then, later, when
kernel_maps__find_symbol() is used, it will also call
maps__find_symbol that already checks if the symtab was loaded,
loading it if needed.

Now if one does 'perf top --hide_kernel_symbols' we won't pay
the price of loading the (many) symbols in /proc/kallsyms or
vmlinux.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1258757489-5978-4-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-top.c

@@ -830,6 +830,8 @@ static void handle_keypress(int c)
 		case 'q':
 		case 'Q':
 			printf("exiting.\n");
+			if (dump_symtab)
+				dsos__fprintf(stderr);
 			exit(0);
 		case 's':
 			prompt_symbol(&sym_filter_entry, "Enter details symbol");
@@ -946,30 +948,6 @@ static int symbol_filter(struct map *map, struct symbol *sym)
 	return 0;
 }
 
-static int parse_symbols(void)
-{
-	struct dso *kernel = dsos__load_kernel();
-
-	if (kernel == NULL)
-		return -1;
-
-	if (dsos__load_modules() < 0)
-		pr_debug("Couldn't read the complete list of modules, "
-			 "continuing...\n");
-
-	if (dsos__load_modules_sym(symbol_filter) < 0)
-		pr_warning("Failed to read module symbols, continuing...\n");
-
-	if (dso__load_kernel_sym(kernel, symbol_filter, 1) <= 0)
-		pr_debug("Couldn't read the complete list of kernel symbols, "
-			 "continuing...\n");
-
-	if (dump_symtab)
-		dsos__fprintf(stderr);
-
-	return 0;
-}
-
 static void event__process_sample(const event_t *self, int counter)
 {
 	u64 ip = self->ip.ip;
@@ -1012,7 +990,7 @@ static void event__process_sample(const event_t *self, int counter)
 		if (hide_kernel_symbols)
 			return;
 
-		sym = kernel_maps__find_symbol(ip, &map);
+		sym = kernel_maps__find_symbol(ip, &map, symbol_filter);
 		if (sym == NULL)
 			return;
 		break;
@@ -1339,7 +1317,7 @@ static const struct option options[] = {
 
 int cmd_top(int argc, const char **argv, const char *prefix __used)
 {
-	int counter;
+	int counter, err;
 
 	page_size = sysconf(_SC_PAGE_SIZE);
 
@@ -1363,10 +1341,11 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
 	if (delay_secs < 1)
 		delay_secs = 1;
 
-	parse_symbols();
+	err = kernel_maps__init(true);
+	if (err < 0)
+		return err;
 	parse_source(sym_filter_entry);
 
-
 	/*
 	 * User specified count overrides default frequency.
 	 */