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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2100C433EF for ; Thu, 7 Apr 2022 14:28:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 867C26B0072; Thu, 7 Apr 2022 10:28:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 817106B0073; Thu, 7 Apr 2022 10:28:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6B7EB6B0074; Thu, 7 Apr 2022 10:28:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 5BE4C6B0072 for ; Thu, 7 Apr 2022 10:28:19 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 33CD12A429 for ; Thu, 7 Apr 2022 14:28:09 +0000 (UTC) X-FDA: 79330312698.03.452FD52 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf15.hostedemail.com (Postfix) with ESMTP id 102A4A0006 for ; Thu, 7 Apr 2022 14:28:07 +0000 (UTC) Received: from kwepemi100006.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KZ3cl5TFKzdZcX; Thu, 7 Apr 2022 22:27:35 +0800 (CST) Received: from kwepemm600017.china.huawei.com (7.193.23.234) by kwepemi100006.china.huawei.com (7.221.188.165) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 7 Apr 2022 22:28:04 +0800 Received: from [10.174.179.234] (10.174.179.234) by kwepemm600017.china.huawei.com (7.193.23.234) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Thu, 7 Apr 2022 22:28:02 +0800 Message-ID: <9788a324-05b2-80d7-d062-4bb10cc4d0ee@huawei.com> Date: Thu, 7 Apr 2022 22:28:02 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [RFC PATCH -next V2 4/7] arm64: add copy_from_user to machine check safe To: Mark Rutland CC: Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Catalin Marinas , Will Deacon , Alexander Viro , , "H. Peter Anvin" , , , References: <20220406091311.3354723-1-tongtiangen@huawei.com> <20220406091311.3354723-5-tongtiangen@huawei.com> From: Tong Tiangen In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemm600017.china.huawei.com (7.193.23.234) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 102A4A0006 X-Stat-Signature: jjkszguxeazi3c3iptusidhkt7dgbihe Authentication-Results: imf15.hostedemail.com; dkim=none; spf=pass (imf15.hostedemail.com: domain of tongtiangen@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=tongtiangen@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-HE-Tag: 1649341687-19082 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 在 2022/4/6 19:19, Mark Rutland 写道: > On Wed, Apr 06, 2022 at 09:13:08AM +0000, Tong Tiangen wrote: >> Add scenarios copy_from_user to machine check safe. >> >> The data copied is user data and is machine check safe, so just kill >> the user process and isolate the error page, not necessary panic. >> >> Signed-off-by: Tong Tiangen >> --- >> arch/arm64/include/asm/asm-uaccess.h | 16 ++++++++++++++++ >> arch/arm64/lib/copy_from_user.S | 11 ++++++----- >> 2 files changed, 22 insertions(+), 5 deletions(-) >> >> diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h >> index 0557af834e03..f31c8978e1af 100644 >> --- a/arch/arm64/include/asm/asm-uaccess.h >> +++ b/arch/arm64/include/asm/asm-uaccess.h >> @@ -92,4 +92,20 @@ alternative_else_nop_endif >> >> _asm_extable 8888b,\l; >> .endm >> + >> + .macro user_ldp_mc l, reg1, reg2, addr, post_inc >> +8888: ldtr \reg1, [\addr]; >> +8889: ldtr \reg2, [\addr, #8]; >> + add \addr, \addr, \post_inc; >> + >> + _asm_extable_mc 8888b, \l; >> + _asm_extable_mc 8889b, \l; >> + .endm >> + >> + .macro user_ldst_mc l, inst, reg, addr, post_inc >> +8888: \inst \reg, [\addr]; >> + add \addr, \addr, \post_inc; >> + >> + _asm_extable_mc 8888b, \l; >> + .endm >> #endif >> diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S >> index 34e317907524..d9d7c5291871 100644 >> --- a/arch/arm64/lib/copy_from_user.S >> +++ b/arch/arm64/lib/copy_from_user.S >> @@ -21,7 +21,7 @@ >> */ >> >> .macro ldrb1 reg, ptr, val >> - user_ldst 9998f, ldtrb, \reg, \ptr, \val >> + user_ldst_mc 9998f, ldtrb, \reg, \ptr, \val >> .endm >> >> .macro strb1 reg, ptr, val >> @@ -29,7 +29,7 @@ >> .endm >> >> .macro ldrh1 reg, ptr, val >> - user_ldst 9997f, ldtrh, \reg, \ptr, \val >> + user_ldst_mc 9997f, ldtrh, \reg, \ptr, \val >> .endm >> >> .macro strh1 reg, ptr, val >> @@ -37,7 +37,7 @@ >> .endm >> >> .macro ldr1 reg, ptr, val >> - user_ldst 9997f, ldtr, \reg, \ptr, \val >> + user_ldst_mc 9997f, ldtr, \reg, \ptr, \val >> .endm >> >> .macro str1 reg, ptr, val >> @@ -45,7 +45,7 @@ >> .endm >> >> .macro ldp1 reg1, reg2, ptr, val >> - user_ldp 9997f, \reg1, \reg2, \ptr, \val >> + user_ldp_mc 9997f, \reg1, \reg2, \ptr, \val >> .endm >> >> .macro stp1 reg1, reg2, ptr, val >> @@ -62,7 +62,8 @@ SYM_FUNC_START(__arch_copy_from_user) >> ret >> >> // Exception fixups >> -9997: cmp dst, dstin >> +9997: cbz x0, 9998f // Check machine check exception >> + cmp dst, dstin >> b.ne 9998f > > If you look at the copy template, you'd see that `dstin` *is* x0. > > Consier if we took a non-SEA fault. The the fixup handler will overwrite x0, > it's likely `dst` != `dstin`, and we'll branch to the byte-by-byte copy. Or if > we're doing something odd and mmap_min_addr is 0, we can do the wrong thing the > other way around and *not* branch to the byte-by-byte copy when we should. > > So this is at best confusing, but likely broken too. > > Thanks, > Mark. OK, missing that, will be fixed in next verison. Thanks, Tong. > >> // Before being absolutely sure we couldn't copy anything, try harder >> USER(9998f, ldtrb tmp1w, [srcin]) >> -- >> 2.18.0.huawei.25 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > .