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>

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index bb5d32f..f119e85 100644 (file)
--- 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