From patchwork Thu Sep 1 13:35:59 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Murzin X-Patchwork-Id: 9309063 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 DC8ED60756 for ; Thu, 1 Sep 2016 13:38:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E359E29376 for ; Thu, 1 Sep 2016 13:38:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D77EF29420; Thu, 1 Sep 2016 13:38:22 +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=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 6B64D29376 for ; Thu, 1 Sep 2016 13:38:22 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bfSAh-0001rN-Vo; Thu, 01 Sep 2016 13:36:48 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bfSAc-0001k1-Ay for linux-arm-kernel@lists.infradead.org; Thu, 01 Sep 2016 13:36:44 +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 CB8E716; Thu, 1 Sep 2016 06:36:20 -0700 (PDT) Received: from login2.euhpc.arm.com (login2.euhpc.arm.com [10.6.26.144]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 18EC23F246; Thu, 1 Sep 2016 06:36:19 -0700 (PDT) From: Vladimir Murzin To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: kernel: do not need to reset UAO on exception entry Date: Thu, 1 Sep 2016 14:35:59 +0100 Message-Id: <1472736959-25686-1-git-send-email-vladimir.murzin@arm.com> X-Mailer: git-send-email 2.0.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160901_063642_502976_591E6EF1 X-CRM114-Status: UNSURE ( 7.50 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: catalin.marinas@arm.com, will.deacon@arm.com, james.morse@arm.com 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 Commit e19a6ee2460b ("arm64: kernel: Save and restore UAO and addr_limit on exception entry") states that exception handler inherits the original PSTATE.UAO value, so UAO needes to be reset explicitly. However, ARM 8.2 Extension documentation says: PSTATE.UAO is copied to SPSR_ELx.UAO and is then set to 0 on an exception taken from AArch64 to AArch64 so hardware already does the right thing. Signed-off-by: Vladimir Murzin Acked-by: James Morse --- arch/arm64/kernel/entry.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 441420c..7c9bb43 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -104,7 +104,7 @@ str x20, [sp, #S_ORIG_ADDR_LIMIT] mov x20, #TASK_SIZE_64 str x20, [tsk, #TI_ADDR_LIMIT] - ALTERNATIVE(nop, SET_PSTATE_UAO(0), ARM64_HAS_UAO, CONFIG_ARM64_UAO) + /* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */ .endif /* \el == 0 */ mrs x22, elr_el1 mrs x23, spsr_el1