From patchwork Fri Sep 17 05:58:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Daniel Kachhap X-Patchwork-Id: 12501091 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=-17.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 465CDC433EF for ; Fri, 17 Sep 2021 06:00:54 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 08A3661019 for ; Fri, 17 Sep 2021 06:00:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 08A3661019 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date:Subject:Cc:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=6vvpGw0NqCraxy9iAWW6h3u7lnFDPh//fAAvm/YX/Jc=; b=u+w60abMaCHuU3 DKq0O582G2nqZByQZ2Ba1+c54e/YaBWnblK13RVBYOEZc+dpSIJ7SnBbr2aeRTfOgaCn81G2SMlXX 5kwwTMvXkiG7fc5SGkqs4JdmuL+14pGVJ98lhclAbwaWW8ZIdkTQxXg1FjsgwTk1KGXamucaIEYfj 96vpTDX3aRA5yBkCEcDClZgV0lMiwZ0Wls9cVQAxU2wRO1StcHK0OdLxFNqn1pzx/GDI4ql9t8iqr psnR7+PGLVWzNVhE1OvDa8OxZHLVLcu6kTkud4HKlRoPnJF/zF2CIrxqbr0Npx9HeuoiuoRaLm1RS p+WZQaD8Tm3XzaBsYGMw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mR6tL-00DGDy-2u; Fri, 17 Sep 2021 05:58:31 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mR6tH-00DGDR-H8 for linux-arm-kernel@lists.infradead.org; Fri, 17 Sep 2021 05:58:28 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 738F331B; Thu, 16 Sep 2021 22:58:22 -0700 (PDT) Received: from a077416.arm.com (unknown [10.163.42.222]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 595343F5A1; Thu, 16 Sep 2021 22:58:19 -0700 (PDT) From: Amit Daniel Kachhap To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Mark Rutland , Vincenzo Frascino , Kevin Brodsky , Amit Daniel Kachhap , Catalin Marinas , Will Deacon Subject: [PATCH v2] arm64/traps: Avoid unnecessary kernel/user pointer conversion Date: Fri, 17 Sep 2021 11:28:11 +0530 Message-Id: <20210917055811.22341-1-amit.kachhap@arm.com> X-Mailer: git-send-email 2.17.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210916_225827_654268_148DAA9D X-CRM114-Status: GOOD ( 11.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Annotating a pointer from kernel to __user and then back again requires an extra __force annotation to silent sparse warning. In call_undef_hook() this unnecessary complexity can be avoided by modifying the intermediate user pointer to unsigned long. This way there is no inter-changeable use of user and kernel pointers and the code is consistent. Note: This patch adds no functional changes to code. Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Amit Daniel Kachhap Acked-by: Mark Rutland --- Changes from v1: * Instead of directly using instruction_pointer() for kernel pointers, modified the pc type from void __user * to unsigned long as suggested by Mark Rutland. arch/arm64/kernel/traps.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index b03e383d944a..09236751283e 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -400,11 +400,11 @@ static int call_undef_hook(struct pt_regs *regs) unsigned long flags; u32 instr; int (*fn)(struct pt_regs *regs, u32 instr) = NULL; - void __user *pc = (void __user *)instruction_pointer(regs); + unsigned long pc = instruction_pointer(regs); if (!user_mode(regs)) { __le32 instr_le; - if (get_kernel_nofault(instr_le, (__force __le32 *)pc)) + if (get_kernel_nofault(instr_le, (__le32 *)pc)) goto exit; instr = le32_to_cpu(instr_le); } else if (compat_thumb_mode(regs)) {