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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 22192C43332 for ; Fri, 5 Mar 2021 12:40:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 015966502A for ; Fri, 5 Mar 2021 12:40:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233336AbhCEMkZ (ORCPT ); Fri, 5 Mar 2021 07:40:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:54298 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232203AbhCEMjs (ORCPT ); Fri, 5 Mar 2021 07:39:48 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5C8A76501D; Fri, 5 Mar 2021 12:39:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614947986; bh=tmbZ0ujeLAKfplvADqenZ3g25Ac5KzfRJiS9W3Sutrs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NC50c2uavEKx8I8ZcW6JyL+zAoXAT7NjrUF6BwzSqFV75OYre8xdH46Q7JHU5XnEH BvdfnFygwxvBqddDL+TVMFrUo/Jz6ofH2D0B+s3TaB83RbiGyuMe2Iii0v4tBFJbus scSY/MdiRAXG0SzvXQHxcRzsVy2I1eEemMmadF6o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Robin Murphy , Will Deacon , Ben Hutchings Subject: [PATCH 4.14 09/39] arm64: cmpxchg: Use "K" instead of "L" for ll/sc immediate constraint Date: Fri, 5 Mar 2021 13:22:08 +0100 Message-Id: <20210305120852.226425678@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210305120851.751937389@linuxfoundation.org> References: <20210305120851.751937389@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: Will Deacon commit 4230509978f2921182da4e9197964dccdbe463c3 upstream. The "L" AArch64 machine constraint, which we use for the "old" value in an LL/SC cmpxchg(), generates an immediate that is suitable for a 64-bit logical instruction. However, for cmpxchg() operations on types smaller than 64 bits, this constraint can result in an invalid instruction which is correctly rejected by GAS, such as EOR W1, W1, #0xffffffff. Whilst we could special-case the constraint based on the cmpxchg size, it's far easier to change the constraint to "K" and put up with using a register for large 64-bit immediates. For out-of-line LL/SC atomics, this is all moot anyway. Reported-by: Robin Murphy Signed-off-by: Will Deacon Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/atomic_ll_sc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/arm64/include/asm/atomic_ll_sc.h +++ b/arch/arm64/include/asm/atomic_ll_sc.h @@ -268,7 +268,7 @@ __LL_SC_PREFIX(__cmpxchg_case_##name##sz "2:" \ : [tmp] "=&r" (tmp), [oldval] "=&r" (oldval), \ [v] "+Q" (*(u##sz *)ptr) \ - : [old] "Lr" (old), [new] "r" (new) \ + : [old] "Kr" (old), [new] "r" (new) \ : cl); \ \ return oldval; \