[PATCH 03/12] perf symbols: /proc/kallsyms does not sort module symbols

Arnaldo Carvalho de Melo
2011-09-23T20:26:49Z

From: Anton Blanchard <anton@samba.org>

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>
---
tools/perf/util/symbol.c | 33 +++++++++++----------------------
1 files changed, 11 insertions(+), 22 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index bb5d32f..f119e85 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
--
1.6.2.5