From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753053AbbJONZc (ORCPT ); Thu, 15 Oct 2015 09:25:32 -0400 Received: from eu-smtp-delivery-143.mimecast.com ([146.101.78.143]:62815 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752490AbbJONZb convert rfc822-to-8bit (ORCPT ); Thu, 15 Oct 2015 09:25:31 -0400 Message-ID: <561FA948.5080505@arm.com> Date: Thu, 15 Oct 2015 14:25:28 +0100 From: Vladimir Murzin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Will Deacon CC: Russell King - ARM Linux , Shengjiu Wang , "ard.biesheuvel@linaro.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "nico@linaro.org" , Punit Agrawal , Catalin Marinas Subject: Re: [PATCH] ARM: SWP emulation: Restore original *data when failed References: <1444791077-26020-1-git-send-email-shengjiu.wang@freescale.com> <20151015082417.GX32532@n2100.arm.linux.org.uk> <20151015083629.GA32630@shlinux2> <20151015085700.GY32532@n2100.arm.linux.org.uk> <561F6F3B.6030607@arm.com> <20151015130247.GB29301@arm.com> In-Reply-To: <20151015130247.GB29301@arm.com> X-OriginalArrivalTime: 15 Oct 2015 13:25:28.0781 (UTC) FILETIME=[F57A7FD0:01D1074C] X-MC-Unique: t8Zxt7-hSwWNUdGzuOBXxg-1 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/10/15 14:02, Will Deacon wrote: > On Thu, Oct 15, 2015 at 10:17:47AM +0100, Vladimir Murzin wrote: >> We might need the same change for arm64 counterpart (see >> arch/arm64/kernel/armv8_deprecated.c). > > Something like below? Looks good. Should these two go to stable? Vladimir > > Will > >>>From 63c3e83073cfac2e011adf0ed6f335275cc977a7 Mon Sep 17 00:00:00 2001 > From: Will Deacon > Date: Thu, 15 Oct 2015 13:55:53 +0100 > Subject: [PATCH] arm64: compat: fix stxr failure case in SWP emulation > > If the STXR instruction fails in the SWP emulation code, we leave *data > overwritten with the loaded value, therefore corrupting the data written > by a subsequent, successful attempt. > > This patch re-jigs the code so that we only write back to *data once we > know that the update has happened. > > Reported-by: Shengjiu Wang > Reported-by: Vladimir Murzin > Signed-off-by: Will Deacon > --- > arch/arm64/kernel/armv8_deprecated.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c > index bcee7abac68e..6039d1eb5912 100644 > --- a/arch/arm64/kernel/armv8_deprecated.c > +++ b/arch/arm64/kernel/armv8_deprecated.c > @@ -284,12 +284,12 @@ static void register_insn_emulation_sysctl(struct ctl_table *table) > __asm__ __volatile__( \ > ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ > CONFIG_ARM64_PAN) \ > - " mov %w2, %w1\n" \ > - "0: ldxr"B" %w1, [%3]\n" \ > - "1: stxr"B" %w0, %w2, [%3]\n" \ > + "0: ldxr"B" %w2, [%3]\n" \ > + "1: stxr"B" %w0, %w1, [%3]\n" \ > " cbz %w0, 2f\n" \ > " mov %w0, %w4\n" \ > "2:\n" \ > + " mov %w1, %w2\n" \ > " .pushsection .fixup,\"ax\"\n" \ > " .align 2\n" \ > "3: mov %w0, %w5\n" \ >