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 97335C433F5 for ; Thu, 19 May 2022 07:09:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2718B6B0072; Thu, 19 May 2022 03:09:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 221596B0073; Thu, 19 May 2022 03:09:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 10FF28D0001; Thu, 19 May 2022 03:09:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 025D06B0072 for ; Thu, 19 May 2022 03:09:29 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id A8A2960B75 for ; Thu, 19 May 2022 07:09:29 +0000 (UTC) X-FDA: 79481616858.20.3817A5B Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf02.hostedemail.com (Postfix) with ESMTP id AB69A80011 for ; Thu, 19 May 2022 07:09:27 +0000 (UTC) Received: from kwepemi100016.china.huawei.com (unknown [172.30.72.54]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4L3gtC0p3lz1JC6B; Thu, 19 May 2022 15:08:03 +0800 (CST) Received: from kwepemm600017.china.huawei.com (7.193.23.234) by kwepemi100016.china.huawei.com (7.221.188.123) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 19 May 2022 15:09:25 +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 15.1.2375.24; Thu, 19 May 2022 15:09:23 +0800 Message-ID: Date: Thu, 19 May 2022 15:09:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH -next v4 6/7] arm64: add {get, put}_user to machine check safe To: Mark Rutland CC: James Morse , Andrew Morton , Thomas Gleixner , "Ingo Molnar" , Borislav Petkov , Robin Murphy , Dave Hansen , "Catalin Marinas" , Will Deacon , "Alexander Viro" , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , , "H . Peter Anvin" , , , , , Kefeng Wang , Xie XiuQi , Guohanjun References: <20220420030418.3189040-1-tongtiangen@huawei.com> <20220420030418.3189040-7-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: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemm600017.china.huawei.com (7.193.23.234) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: AB69A80011 Authentication-Results: imf02.hostedemail.com; dkim=none; spf=pass (imf02.hostedemail.com: domain of tongtiangen@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=tongtiangen@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-Stat-Signature: jnntfud5jggfjhq1pnmdhnkxea1maap4 X-HE-Tag: 1652944167-432693 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 2022/5/13 23:39, Mark Rutland 写道: > On Wed, Apr 20, 2022 at 03:04:17AM +0000, Tong Tiangen wrote: >> Add {get, put}_user() to machine check safe. >> >> If get/put fail due to hardware memory error, only the relevant processes >> are affected, so killing the user process and isolate the user page with >> hardware memory errors is a more reasonable choice than kernel panic. >> >> Add new extable type EX_TYPE_UACCESS_MC_ERR_ZERO which can be used for >> uaccess that can be recovered from hardware memory errors. The difference >> from EX_TYPE_UACCESS_MC is that this type also sets additional two target >> register which save error code and value needs to be set zero. > > Why does this need to be in any way distinct from the existing > EX_TYPE_UACCESS_ERR_ZERO ? > > Other than the case where we currently (ab)use that for > copy_{to,from}_kernel_nofault(), where do we *not* want to use > EX_TYPE_UACCESS_ERR_ZERO and *not* recover from a memory error? > > Thanks, > Mark. There are some cases (futex/__user_cache_maint()/__user_swpX_asm()) using EX_TYPE_UACCESS_ERR_ZERO, for these cases, whether to restore is not yet determined, let's discuss in patch 3/7. Thanks, Tong. > >> >> Signed-off-by: Tong Tiangen >> --- >> arch/arm64/include/asm/asm-extable.h | 14 ++++++++++++++ >> arch/arm64/include/asm/uaccess.h | 4 ++-- >> arch/arm64/mm/extable.c | 4 ++++ >> 3 files changed, 20 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h >> index 75b2c00e9523..80410899a9ad 100644 >> --- a/arch/arm64/include/asm/asm-extable.h >> +++ b/arch/arm64/include/asm/asm-extable.h >> @@ -13,6 +13,7 @@ >> >> /* _MC indicates that can fixup from machine check errors */ >> #define EX_TYPE_UACCESS_MC 5 >> +#define EX_TYPE_UACCESS_MC_ERR_ZERO 6 >> >> #ifdef __ASSEMBLY__ >> >> @@ -78,6 +79,15 @@ >> #define EX_DATA_REG(reg, gpr) \ >> "((.L__gpr_num_" #gpr ") << " __stringify(EX_DATA_REG_##reg##_SHIFT) ")" >> >> +#define _ASM_EXTABLE_UACCESS_MC_ERR_ZERO(insn, fixup, err, zero) \ >> + __DEFINE_ASM_GPR_NUMS \ >> + __ASM_EXTABLE_RAW(#insn, #fixup, \ >> + __stringify(EX_TYPE_UACCESS_MC_ERR_ZERO), \ >> + "(" \ >> + EX_DATA_REG(ERR, err) " | " \ >> + EX_DATA_REG(ZERO, zero) \ >> + ")") >> + >> #define _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero) \ >> __DEFINE_ASM_GPR_NUMS \ >> __ASM_EXTABLE_RAW(#insn, #fixup, \ >> @@ -90,6 +100,10 @@ >> #define _ASM_EXTABLE_UACCESS_ERR(insn, fixup, err) \ >> _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, wzr) >> >> + >> +#define _ASM_EXTABLE_UACCESS_MC_ERR(insn, fixup, err) \ >> + _ASM_EXTABLE_UACCESS_MC_ERR_ZERO(insn, fixup, err, wzr) >> + >> #define EX_DATA_REG_DATA_SHIFT 0 >> #define EX_DATA_REG_DATA GENMASK(4, 0) >> #define EX_DATA_REG_ADDR_SHIFT 5 >> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h >> index e8dce0cc5eaa..e41b47df48b0 100644 >> --- a/arch/arm64/include/asm/uaccess.h >> +++ b/arch/arm64/include/asm/uaccess.h >> @@ -236,7 +236,7 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) >> asm volatile( \ >> "1: " load " " reg "1, [%2]\n" \ >> "2:\n" \ >> - _ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %w0, %w1) \ >> + _ASM_EXTABLE_UACCESS_MC_ERR_ZERO(1b, 2b, %w0, %w1) \ >> : "+r" (err), "=&r" (x) \ >> : "r" (addr)) >> >> @@ -325,7 +325,7 @@ do { \ >> asm volatile( \ >> "1: " store " " reg "1, [%2]\n" \ >> "2:\n" \ >> - _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \ >> + _ASM_EXTABLE_UACCESS_MC_ERR(1b, 2b, %w0) \ >> : "+r" (err) \ >> : "r" (x), "r" (addr)) >> >> diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c >> index 525876c3ebf4..1023ccdb2f89 100644 >> --- a/arch/arm64/mm/extable.c >> +++ b/arch/arm64/mm/extable.c >> @@ -88,6 +88,7 @@ bool fixup_exception(struct pt_regs *regs) >> case EX_TYPE_BPF: >> return ex_handler_bpf(ex, regs); >> case EX_TYPE_UACCESS_ERR_ZERO: >> + case EX_TYPE_UACCESS_MC_ERR_ZERO: >> return ex_handler_uaccess_err_zero(ex, regs); >> case EX_TYPE_LOAD_UNALIGNED_ZEROPAD: >> return ex_handler_load_unaligned_zeropad(ex, regs); >> @@ -107,6 +108,9 @@ bool fixup_exception_mc(struct pt_regs *regs) >> switch (ex->type) { >> case EX_TYPE_UACCESS_MC: >> return ex_handler_uaccess_type(ex, regs, FIXUP_TYPE_MC); >> + case EX_TYPE_UACCESS_MC_ERR_ZERO: >> + return ex_handler_uaccess_err_zero(ex, regs); >> + >> } >> >> return false; >> -- >> 2.25.1 >> > .