From c1f47b454ce759d7b13604137a233cad4617e1e8 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 21 Jun 2009 13:58:51 +0200 Subject: [PATCH] perf_counter tools: Fix vmlinux fallback when running on a different kernel Lucas De Marchi reported that perf report and perf annotate displays mismatching profile if a perf.data is analyzed on an older kernel - even if the correct vmlinux is specified via the -k option. The reason is the fallback path in util/symbol.c:dso__load_kernel(): int dso__load_kernel(struct dso *self, const char *vmlinux, symbol_filter_t filter, int verbose) { int err = -1; if (vmlinux) err = dso__load_vmlinux(self, vmlinux, filter, verbose); if (err) err = dso__load_kallsyms(self, filter, verbose); return err; } dso__load_vmlinux() returns negative on error, but on success it returns the number of symbols loaded - which confuses the function to load the kallsyms. This is normally harmless, as reporting is usually performed on the same kernel that is analyzed - but if there's a mismatch then we load the wrong kallsyms and create a non-sensical symbol tree. The fix is to only fall back to kallsyms on errors. Reported-by: Lucas De Marchi Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo LKML-Reference: Signed-off-by: Ingo Molnar --- tools/perf/util/symbol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 86e14375e74e..01b62fa03996 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -629,7 +629,7 @@ int dso__load_kernel(struct dso *self, const char *vmlinux, if (vmlinux) err = dso__load_vmlinux(self, vmlinux, filter, verbose); - if (err) + if (err < 0) err = dso__load_kallsyms(self, filter, verbose); return err;