perf symbols: /proc/kallsyms does not sort module symbols

kallsyms__parse assumes that /proc/kallsyms is sorted and sets the end
of the previous symbol to the start of the current one.

Unfortunately module symbols are not sorted, eg:

ffffffffa0081f30 t e1000_clean_rx_irq   [e1000e]
ffffffffa00817a0 t e1000_alloc_rx_buffers       [e1000e]

Some symbols end up with a negative length and others have a length
larger than they should. This results in confusing perf output.

We already have a function to fixup the end of zero length symbols so
use that instead.

Cc: Eric B Munson <emunson@mgebm.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110824065242.969681349@samba.org
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 11 insertions, 22 deletions

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index bb5d32f38af2..f119e85dc6c2 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -438,18 +438,11 @@ int kallsyms__parse(const char *filename, void *arg,
         char *line = NULL;
         size_t n;
         int err = -1;
-        u64 prev_start = 0;
-        char prev_symbol_type = 0;
-        char *prev_symbol_name;
         FILE *file = fopen(filename, "r");
 
         if (file == NULL)
                 goto out_failure;
 
-        prev_symbol_name = malloc(KSYM_NAME_LEN);
-        if (prev_symbol_name == NULL)
-                goto out_close;
-
         err = 0;
 
         while (!feof(file)) {
@@ -480,24 +473,18 @@ int kallsyms__parse(const char *filename, void *arg,
                         break;
                 }
 
-                if (prev_symbol_type) {
-                        u64 end = start;
-                        if (end != prev_start)
-                                --end;
-                        err = process_symbol(arg, prev_symbol_name,
-                                             prev_symbol_type, prev_start, end);
-                        if (err)
-                                break;
-                }
-
-                memcpy(prev_symbol_name, symbol_name, len + 1);
-                prev_symbol_type = symbol_type;
-                prev_start = start;
+                /*
+                 * module symbols are not sorted so we add all
+                 * symbols with zero length and rely on
+                 * symbols__fixup_end() to fix it up.
+                 */
+                err = process_symbol(arg, symbol_name,
+                                     symbol_type, start, start);
+                if (err)
+                        break;
         }
 
-        free(prev_symbol_name);
         free(line);
-out_close:
         fclose(file);
         return err;
 
@@ -703,6 +690,8 @@ int dso__load_kallsyms(struct dso *dso, const char *filename,
         if (dso__load_all_kallsyms(dso, filename, map) < 0)
                 return -1;
 
+        symbols__fixup_end(&dso->symbols[map->type]);
+
         if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
                 dso->symtab_type = SYMTAB__GUEST_KALLSYMS;
         else