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 5DF29C43219 for ; Tue, 5 Apr 2022 23:42:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1578919AbiDEXZc (ORCPT ); Tue, 5 Apr 2022 19:25:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42278 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356467AbiDEKXz (ORCPT ); Tue, 5 Apr 2022 06:23:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1FE2BC87C; Tue, 5 Apr 2022 03:08:22 -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 400726167E; Tue, 5 Apr 2022 10:08:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50916C385A1; Tue, 5 Apr 2022 10:08:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649153301; bh=xLZ0g/VqrKpcqSVcW8pSHG+RRfkKMtUdbYig9w7nVn8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EX7tuzCINvLe9TaTKfksA28nv11farQwWnVYCXCyEhrDbz5OW4qrKDzcEWFtw9jik yn/TleKcKpPJs3uWQi4756+HRu0j4U19AgYGPWMN9UMobBVAYd/d3M6CJKNJYK10dk mwDC8H7SPGgqjBDxC9wwuPxWn75wr5yrRAA331UI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "Peter Zijlstra (Intel)" , Mathieu Desnoyers , Sasha Levin Subject: [PATCH 5.10 175/599] rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs() Date: Tue, 5 Apr 2022 09:27:49 +0200 Message-Id: <20220405070304.050051081@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070258.802373272@linuxfoundation.org> References: <20220405070258.802373272@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit 5e0ccd4a3b01c5a71732a13186ca110a138516ea ] Commit ec9c82e03a74 ("rseq: uapi: Declare rseq_cs field as union, update includes") added regressions for our servers. Using copy_from_user() and clear_user() for 64bit values is suboptimal. We can use faster put_user() and get_user() on 64bit arches. Signed-off-by: Eric Dumazet Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Mathieu Desnoyers Link: https://lkml.kernel.org/r/20210413203352.71350-4-eric.dumazet@gmail.com Signed-off-by: Sasha Levin --- kernel/rseq.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/rseq.c b/kernel/rseq.c index 0077713bf240..1b4547e0d841 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -120,8 +120,13 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) u32 sig; int ret; +#ifdef CONFIG_64BIT + if (get_user(ptr, &t->rseq->rseq_cs.ptr64)) + return -EFAULT; +#else if (copy_from_user(&ptr, &t->rseq->rseq_cs.ptr64, sizeof(ptr))) return -EFAULT; +#endif if (!ptr) { memset(rseq_cs, 0, sizeof(*rseq_cs)); return 0; @@ -204,9 +209,13 @@ static int clear_rseq_cs(struct task_struct *t) * * Set rseq_cs to NULL. */ +#ifdef CONFIG_64BIT + return put_user(0UL, &t->rseq->rseq_cs.ptr64); +#else if (clear_user(&t->rseq->rseq_cs.ptr64, sizeof(t->rseq->rseq_cs.ptr64))) return -EFAULT; return 0; +#endif } /* -- 2.34.1