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 B9115C43603 for ; Fri, 5 Mar 2021 12:38:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A83DF65012 for ; Fri, 5 Mar 2021 12:38:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232916AbhCEMiV (ORCPT ); Fri, 5 Mar 2021 07:38:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:50332 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233212AbhCEMhX (ORCPT ); Fri, 5 Mar 2021 07:37:23 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 87F2D65012; Fri, 5 Mar 2021 12:37:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614947843; bh=tmbZ0ujeLAKfplvADqenZ3g25Ac5KzfRJiS9W3Sutrs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=x9qUe+GZksFwNqluc8HxVrRwhKN90mJN+fMDbRpQuR6wk9eQvJINULBUIVeL8bana +xfz1a9paMIcKmDHCVOLOjpn8cS0e/glp9MV+/E4CCrRX+1zYT299dEqw/jpU6jlsS AVvd4HRmSgAg5Z2w5J83s0E8rp5UidCi4ngRT4Nw= 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 4.19 07/52] arm64: cmpxchg: Use "K" instead of "L" for ll/sc immediate constraint Date: Fri, 5 Mar 2021 13:21:38 +0100 Message-Id: <20210305120854.016708187@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210305120853.659441428@linuxfoundation.org> References: <20210305120853.659441428@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; \