linux-kernel - [PATCH perf/urgent] perf tools: Fix is_bpf

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Date:   Tue, 12 May 2020 14:23:10 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>
Subject: [PATCH perf/urgent] perf tools: Fix is_bpf_image function logic

Adrian reported that is_bpf_image is not working the way it was
intended - passing on trampolines and dispatcher names. Instead
it returned true for all the bpf names.

The reason even this logic worked properly is that all bpf objects,
even trampolines and dispatcher, were assigned DSO_BINARY_TYPE__BPF_IMAGE
binary_type.

The later for bpf_prog objects, the binary_type was fixed in bpf load event
processing, which is executed after the ksymbol code.

Fixing the is_bpf_image logic, so it properly recognizes trampoline
and dispatcher objects.

Reported-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Jiri Olsa <jolsa@...hat.com>
---
 tools/perf/util/machine.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 8ed2135893bb..d5384807372b 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -738,8 +738,8 @@ int machine__process_switch_event(struct machine *machine __maybe_unused,
 
 static int is_bpf_image(const char *name)
 {
-	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) ||
-	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1);
+	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) == 0 ||
+	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1) == 0;
 }
 
 static int machine__process_ksymbol_register(struct machine *machine,
-- 
2.25.4