From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 217B4C43219 for ; Mon, 17 Oct 2022 19:30:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229885AbiJQTaP (ORCPT ); Mon, 17 Oct 2022 15:30:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230237AbiJQT3v (ORCPT ); Mon, 17 Oct 2022 15:29:51 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D506B79EE0; Mon, 17 Oct 2022 12:28:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id BF0CF61218; Mon, 17 Oct 2022 19:27:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23F71C433C1; Mon, 17 Oct 2022 19:27:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666034867; bh=/sbWL9ZHe0D21fIQ7+2B+ATC4P6VpJMi25hzWD3qixc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lw3Oe2cbqI76PHfUenh39Na+3kNO1A0K441gFbTMVFGlGEiF0RpugA0jyceJUM8eP IFll+tuAg2WL91pHS45pMdkaQtTR5SCEHDcHNyRNTQ4WtlR2KdhN/+0qiMdSq1KSCQ F7o0xVJIdITYABlxbhY0nuYjN97dPKzFe7SHkJjfeh5mJaOtWBRpHyT7B4oQ4td68a FwO0JSyYgdHh8mS6ZAXC/odq+oaGwqMgkR/5r8Sn6NvdpBDS5PHpQhcrECILXcMdvy 4ngscN6Pe59rYjEKZ2Pr0o94mDOjbhAMqXIEy86hBP7p8wfCkYYFPKcuXQEFBAz3z+ REME+e8RpHYiw== From: SeongJae Park To: Sumanth Korikkar Cc: olsajiri@gmail.com, bpf@vger.kernel.org, gor@linux.ibm.com, hca@linux.ibm.com, iii@linux.ibm.com, linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, namhyung@kernel.org, peterz@infradead.org, svens@linux.ibm.com, tip-bot2@linutronix.de, tmricht@linux.ibm.com, x86@kernel.org Subject: Re: [PATCH] bpf: fix sample_flags for bpf_perf_event_output Date: Mon, 17 Oct 2022 19:27:44 +0000 Message-Id: <20221017192744.1403-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221007081327.1047552-1-sumanthk@linux.ibm.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, The commit that this patch is fixing[1] also causes yet another segfault for 'perf-script' of tracepoint records. For example: $ sudo timeout 3 perf record -e exceptions:page_fault_user [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.228 MB perf.data (74 samples) ] $ sudo perf script Segmentation fault Reverting this patch and the original bug commit[1] fixes the issue. I haven't deep dive yet because I'm not familiar with this area. Anybody has any idea about this? [1] 838d9bb62d13 ("perf: Use sample_flags for raw_data") Thanks, SJ On Fri, 7 Oct 2022 10:13:27 +0200 Sumanth Korikkar wrote: > * Raw data is also filled by bpf_perf_event_output. > * Add sample_flags to indicate raw data. > * This eliminates the segfaults as shown below: > Run ./samples/bpf/trace_output > BUG pid 9 cookie 1001000000004 sized 4 > BUG pid 9 cookie 1001000000004 sized 4 > BUG pid 9 cookie 1001000000004 sized 4 > Segmentation fault (core dumped) > > Fixes: 838d9bb62d13 ("perf: Use sample_flags for raw_data") > Acked-by: Namhyung Kim > Signed-off-by: Sumanth Korikkar > --- > kernel/trace/bpf_trace.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 49fb9ec8366d..1ed08967fb97 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -687,6 +687,7 @@ BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, > > perf_sample_data_init(sd, 0, 0); > sd->raw = &raw; > + sd->sample_flags |= PERF_SAMPLE_RAW; > > err = __bpf_perf_event_output(regs, map, flags, sd); > > @@ -745,6 +746,7 @@ u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, > perf_fetch_caller_regs(regs); > perf_sample_data_init(sd, 0, 0); > sd->raw = &raw; > + sd->sample_flags |= PERF_SAMPLE_RAW; > > ret = __bpf_perf_event_output(regs, map, flags, sd); > out: > -- > 2.36.1