linux-kernel - [PATCH 23/25] perf script: Assume native

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Message-Id: <20190709183126.30257-24-acme@kernel.org>
Date:   Tue,  9 Jul 2019 15:31:24 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Song Liu <songliubraving@...com>,
        David Carrillo Cisneros <davidca@...com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>, kernel-team@...com,
        stable@...r.kernel.org
Subject: [PATCH 23/25] perf script: Assume native_arch for pipe mode

From: Song Liu <songliubraving@...com>

In pipe mode, session->header.env.arch is not populated until the events
are processed. Therefore, the following command crashes:

   perf record -o - | perf script

(gdb) bt

It fails when we try to compare env.arch against uts.machine:

        if (!strcmp(uts.machine, session->header.env.arch) ||
            (!strcmp(uts.machine, "x86_64") &&
             !strcmp(session->header.env.arch, "i386")))
                native_arch = true;

In pipe mode, it is tricky to find env.arch at this stage. To keep it
simple, let's just assume native_arch is always true for pipe mode.

Reported-by: David Carrillo Cisneros <davidca@...com>
Signed-off-by: Song Liu <songliubraving@...com>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: kernel-team@...com
Cc: stable@...r.kernel.org #v5.1+
Fixes: 3ab481a1cfe1 ("perf script: Support insn output for normal samples")
Link: http://lkml.kernel.org/r/20190621014438.810342-1-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-script.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index b3536820f9a8..79367087bd18 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -3752,7 +3752,8 @@ int cmd_script(int argc, const char **argv)
 		goto out_delete;
 
 	uname(&uts);
-	if (!strcmp(uts.machine, session->header.env.arch) ||
+	if (data.is_pipe ||  /* assume pipe_mode indicates native_arch */
+	    !strcmp(uts.machine, session->header.env.arch) ||
 	    (!strcmp(uts.machine, "x86_64") &&
 	     !strcmp(session->header.env.arch, "i386")))
 		native_arch = true;
-- 
2.21.0