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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54714C5B57D for ; Wed, 3 Jul 2019 02:20:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26EB121873 for ; Wed, 3 Jul 2019 02:20:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562120403; bh=mUb06GlPkIZX2TWwchCmZNTU+3knEUqDQHpJxoUKJdk=; h=From:To:Cc:Subject:Date:List-ID:From; b=V5OKwvd5G600F2mc/FNrMpbiR934yZnpPb0MCIY6/6w1aphYcHshZiU0t0LLnvpU1 7Nsy6LbvbxIrg1HsYacoojoFFlkjAeqU48yCjj96pS50WuPw2R37eB1QPIawTD+XZq XysMDCGR5w2Qg8vhZatY/YRjqYrZdiSQyqg+B2ZQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728320AbfGCCSz (ORCPT ); Tue, 2 Jul 2019 22:18:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:56672 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727773AbfGCCSv (ORCPT ); Tue, 2 Jul 2019 22:18:51 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AB5C821874; Wed, 3 Jul 2019 02:18:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562120330; bh=mUb06GlPkIZX2TWwchCmZNTU+3knEUqDQHpJxoUKJdk=; h=From:To:Cc:Subject:Date:From; b=LoJOSwo9PDA55/C33iQ9iLSWy3SuETzmFvyITBNgAAYGqzEW9qBtqNJDtG1ky0Sab DAi2kvjjsoCcC1dfaZ/IO5PE8sn6/d5B0ka8S0pbAYg1tM05zaAoakP9CyKgkrTe+c M5T5y9yjQM83fGbzSWi3oy5oVHjDG9rGYa7M7SPY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Peter Zijlstra , Ravi Bangoria , Young Xiao <92siuyang@gmail.com>, Will Deacon , Arnaldo Carvalho de Melo , Frederic Weisbecker , Jiri Olsa , Linus Torvalds , Michael Ellerman , "Naveen N . Rao" , Stephane Eranian , Thomas Gleixner , Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL 4.9 1/8] perf/core: Fix perf_sample_regs_user() mm check Date: Tue, 2 Jul 2019 22:18:40 -0400 Message-Id: <20190703021847.18542-1-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra [ Upstream commit 085ebfe937d7a7a5df1729f35a12d6d655fea68c ] perf_sample_regs_user() uses 'current->mm' to test for the presence of userspace, but this is insufficient, consider use_mm(). A better test is: '!(current->flags & PF_KTHREAD)', exec() clears PF_KTHREAD after it sets the new ->mm but before it drops to userspace for the first time. Possibly obsoletes: bf05fc25f268 ("powerpc/perf: Fix oops when kthread execs user process") Reported-by: Ravi Bangoria Reported-by: Young Xiao <92siuyang@gmail.com> Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Linus Torvalds Cc: Michael Ellerman Cc: Naveen N. Rao Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Fixes: 4018994f3d87 ("perf: Add ability to attach user level registers dump to sample") Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 7929526e96e2..93d7333c64d8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5492,7 +5492,7 @@ static void perf_sample_regs_user(struct perf_regs *regs_user, if (user_mode(regs)) { regs_user->abi = perf_reg_abi(current); regs_user->regs = regs; - } else if (current->mm) { + } else if (!(current->flags & PF_KTHREAD)) { perf_get_regs_user(regs_user, regs, regs_user_copy); } else { regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE; -- 2.20.1