From patchwork Mon May 21 18:14:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 10416173 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 8E61D6032C for ; Mon, 21 May 2018 18:14:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7D27B289E2 for ; Mon, 21 May 2018 18:14:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 71714289ED; Mon, 21 May 2018 18:14:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4BB4E289E2 for ; Mon, 21 May 2018 18:14:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: Subject: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=Ibl6BP1K1zND25vzq8kIAuVKHk4WnmgChIKZ8/GGew0=; b=RDP zKl7i6YBC5NjcTqDS+AitYH8dhhg84GLkS0ViG6/LDmmH1tJf9kI1lDDRKXTeyTQafLiKCPTjSFZJ uWDpBGqRaJeOAnlgEuyO7WLBtywrK7I07x1uLULTMD18/Qymz64skL2kkRwxEUOL5fA7fvjwuVVr3 2ys6eTnOqGrURZYunLUaJyTDVLLPZrAmNV+hW5wuzM8a1EpErQKoYSEs3eEfmuvrpkKil33WEbxJc GFaNTzPYs7ELd62Lp74tzEv/2PkiAi9my5tLBOQ+0XmzUMzc3Np66G0cZJ5NQ+YR8VuUQEhUGtZIx 7cxCvQgEwlt2l0jwYP3T0UqUkLgf9YA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fKpJx-0003Uv-6v; Mon, 21 May 2018 18:14:09 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fKpJu-0003UD-II for linux-arm-kernel@lists.infradead.org; Mon, 21 May 2018 18:14:07 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 75C341435; Mon, 21 May 2018 11:13:56 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4797D3F25D; Mon, 21 May 2018 11:13:56 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id A32321AE44DE; Mon, 21 May 2018 19:14:23 +0100 (BST) From: Will Deacon To: catalin.marinas@arm.com Subject: [PATCH] arm64: Kconfig: Enable LSE atomics by default Date: Mon, 21 May 2018 19:14:22 +0100 Message-Id: <1526926462-19214-1-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180521_111406_612401_3361D89B X-CRM114-Status: GOOD ( 12.27 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Will Deacon , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Now that we're seeing CPUs shipping with LSE atomics, default them to 'on' in Kconfig. CPUs without the instructions will continue to use LDXR/STXR-based sequences, but they will be placed out-of-line by the compiler. Signed-off-by: Will Deacon Acked-by: Marc Zyngier Acked-by: Mark Rutland --- arch/arm64/Kconfig | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 4d98774cf3c7..3aed13626fd7 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1051,6 +1051,7 @@ config ARM64_PAN config ARM64_LSE_ATOMICS bool "Atomic instructions" + default y help As part of the Large System Extensions, ARMv8.1 introduces new atomic instructions that are designed specifically to scale in @@ -1059,7 +1060,8 @@ config ARM64_LSE_ATOMICS Say Y here to make use of these instructions for the in-kernel atomic routines. This incurs a small overhead on CPUs that do not support these instructions and requires the kernel to be - built with binutils >= 2.25. + built with binutils >= 2.25 in order for the new instructions + to be used. config ARM64_VHE bool "Enable support for Virtualization Host Extensions (VHE)"