From patchwork Wed Oct 9 08:42:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11180803 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B9C8E1709 for ; Wed, 9 Oct 2019 08:43:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 917002190F for ; Wed, 9 Oct 2019 08:43:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 917002190F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CC35E8E0006; Wed, 9 Oct 2019 04:43:17 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id C9A998E0003; Wed, 9 Oct 2019 04:43:17 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BD7E88E0006; Wed, 9 Oct 2019 04:43:17 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0136.hostedemail.com [216.40.44.136]) by kanga.kvack.org (Postfix) with ESMTP id 9A46C8E0003 for ; Wed, 9 Oct 2019 04:43:17 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 422EB180AD808 for ; Wed, 9 Oct 2019 08:43:17 +0000 (UTC) X-FDA: 76023606834.27.kitty73_56956ddc7a116 X-Spam-Summary: 10,1,0,8522bd3ac0409e4c,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:bp@alien8.de:hpa@zytor.com:x86@kernel.org:tglx@linutronix.de:akpm@linux-foundation.org:hejianet@gmail.com:kaly.xin@arm.com:nd@arm.com:justin.he@arm.com,RULES_HIT:41:355:379:541:800:960:973:988:989:1260:1261:1345:1359:1437:1534:1541:1711:1730:1747:1777:1792:2393:2559:2562:2895:2901:3138:3139:3140:3141:3142:3352:3865:3866:3867:3868:3871:3872:4250:4321:5007:6119:6261:6737:7903:8634:10004:11026:11473:11657:11658:11914:12043:12048:12296:12297:12438:12555:12895:13069:13311:13357:13523:13524:14096:14181:14384:14394:14721:21080:21451:21627:30054:30070,0,RBL:217.140.110.172:@arm.com:.lbl8.mailshell.net-62.2.0.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,D omainCac X-HE-Tag: kitty73_56956ddc7a116 X-Filterd-Recvd-Size: 2860 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 08:43:14 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 81AC31000; Wed, 9 Oct 2019 01:43:14 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CD89B3F68E; Wed, 9 Oct 2019 01:43:09 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org Cc: Thomas Gleixner , Andrew Morton , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v11 1/4] arm64: cpufeature: introduce helper cpu_has_hw_af() Date: Wed, 9 Oct 2019 16:42:43 +0800 Message-Id: <20191009084246.123354-2-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191009084246.123354-1-justin.he@arm.com> References: <20191009084246.123354-1-justin.he@arm.com> 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: We unconditionally set the HW_AFDBM capability and only enable it on CPUs which really have the feature. But sometimes we need to know whether this cpu has the capability of HW AF. So decouple AF from DBM by a new helper cpu_has_hw_af(). Signed-off-by: Jia He Suggested-by: Suzuki Poulose Reviewed-by: Catalin Marinas --- arch/arm64/include/asm/cpufeature.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 9cde5d2e768f..1a95396ea5c8 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -659,6 +659,20 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) default: return CONFIG_ARM64_PA_BITS; } } + +/* Check whether hardware update of the Access flag is supported */ +static inline bool cpu_has_hw_af(void) +{ + if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) { + u64 mmfr1 = read_cpuid(ID_AA64MMFR1_EL1); + + return !!cpuid_feature_extract_unsigned_field(mmfr1, + ID_AA64MMFR1_HADBS_SHIFT); + } + + return false; +} + #endif /* __ASSEMBLY__ */ #endif From patchwork Wed Oct 9 08:42:44 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11180805 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7AFC71709 for ; Wed, 9 Oct 2019 08:43:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 483082190F for ; Wed, 9 Oct 2019 08:43:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 483082190F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5E4F88E0007; Wed, 9 Oct 2019 04:43:21 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 5951B8E0003; Wed, 9 Oct 2019 04:43:21 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D2148E0007; Wed, 9 Oct 2019 04:43:21 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0207.hostedemail.com [216.40.44.207]) by kanga.kvack.org (Postfix) with ESMTP id 2A5E08E0003 for ; Wed, 9 Oct 2019 04:43:21 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id BDEC4824CA2C for ; Wed, 9 Oct 2019 08:43:20 +0000 (UTC) X-FDA: 76023606960.15.box89_576017624b354 X-Spam-Summary: 2,0,0,09f8eadb8978d8c5,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:bp@alien8.de:hpa@zytor.com:x86@kernel.org:tglx@linutronix.de:akpm@linux-foundation.org:hejianet@gmail.com:kaly.xin@arm.com:nd@arm.com:justin.he@arm.com,RULES_HIT:41:355:379:541:800:960:973:988:989:1260:1261:1345:1359:1437:1534:1541:1711:1730:1747:1777:1792:2393:2559:2562:2693:2901:3138:3139:3140:3141:3142:3352:3865:3867:3868:3871:3872:3874:5007:6119:6261:6737:7903:8634:10004:11026:11657:11658:11914:12043:12048:12114:12297:12438:12555:12895:13069:13161:13229:13311:13357:14096:14181:14384:14394:14721:21080:21451:21627:21795:30051:30054,0,RBL:217.140.110.172:@arm.com:.lbl8.mailshell.net-62.2.0.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache: 0,MSF:no X-HE-Tag: box89_576017624b354 X-Filterd-Recvd-Size: 3072 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 08:43:20 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7F60A1570; Wed, 9 Oct 2019 01:43:19 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E88413F68E; Wed, 9 Oct 2019 01:43:14 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org Cc: Thomas Gleixner , Andrew Morton , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v11 2/4] arm64: mm: implement arch_faults_on_old_pte() on arm64 Date: Wed, 9 Oct 2019 16:42:44 +0800 Message-Id: <20191009084246.123354-3-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191009084246.123354-1-justin.he@arm.com> References: <20191009084246.123354-1-justin.he@arm.com> 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: On arm64 without hardware Access Flag, copying from user will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. We don't always have a hardware-managed Access Flag on arm64. Hence implement arch_faults_on_old_pte on arm64 to indicate that it might cause page fault when accessing old pte. Signed-off-by: Jia He Reviewed-by: Catalin Marinas --- arch/arm64/include/asm/pgtable.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 7576df00eb50..e96fb82f62de 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -885,6 +885,20 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, #define phys_to_ttbr(addr) (addr) #endif +/* + * On arm64 without hardware Access Flag, copying from user will fail because + * the pte is old and cannot be marked young. So we always end up with zeroed + * page after fork() + CoW for pfn mappings. We don't always have a + * hardware-managed access flag on arm64. + */ +static inline bool arch_faults_on_old_pte(void) +{ + WARN_ON(preemptible()); + + return !cpu_has_hw_af(); +} +#define arch_faults_on_old_pte arch_faults_on_old_pte + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_PGTABLE_H */ From patchwork Wed Oct 9 08:42:45 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11180807 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4ACD414ED for ; Wed, 9 Oct 2019 08:43:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1D5EE218DE for ; Wed, 9 Oct 2019 08:43:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1D5EE218DE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4ACA08E0008; Wed, 9 Oct 2019 04:43:26 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 45E1D8E0003; Wed, 9 Oct 2019 04:43:26 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 399848E0008; Wed, 9 Oct 2019 04:43:26 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0224.hostedemail.com [216.40.44.224]) by kanga.kvack.org (Postfix) with ESMTP id 16DE28E0003 for ; Wed, 9 Oct 2019 04:43:26 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id C2AF4180AD806 for ; Wed, 9 Oct 2019 08:43:25 +0000 (UTC) X-FDA: 76023607170.17.sheep52_581b102564c54 X-Spam-Summary: 2,0,0,dd0c7cff148830a1,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:bp@alien8.de:hpa@zytor.com:x86@kernel.org:tglx@linutronix.de:akpm@linux-foundation.org:hejianet@gmail.com:kaly.xin@arm.com:nd@arm.com:justin.he@arm.com,RULES_HIT:41:355:379:541:800:960:973:988:989:1260:1261:1345:1359:1431:1437:1534:1540:1711:1714:1730:1747:1777:1792:1981:2194:2199:2393:2559:2562:2693:2901:3138:3139:3140:3141:3142:3351:3867:3871:3872:3874:4321:5007:6261:6737:7903:8634:10004:11026:11473:11657:11658:11914:12043:12048:12114:12297:12438:12555:12895:12986:13069:13311:13357:14096:14181:14384:14394:14721:21080:21451:21627:30054,0,RBL:217.140.110.172:@arm.com:.lbl8.mailshell.net-62.2.0.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCac he:0,MSF X-HE-Tag: sheep52_581b102564c54 X-Filterd-Recvd-Size: 2568 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 08:43:25 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 85D57337; Wed, 9 Oct 2019 01:43:24 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E419C3F68E; Wed, 9 Oct 2019 01:43:19 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org Cc: Thomas Gleixner , Andrew Morton , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v11 3/4] x86/mm: implement arch_faults_on_old_pte() stub on x86 Date: Wed, 9 Oct 2019 16:42:45 +0800 Message-Id: <20191009084246.123354-4-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191009084246.123354-1-justin.he@arm.com> References: <20191009084246.123354-1-justin.he@arm.com> 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: arch_faults_on_old_pte is a helper to indicate that it might cause page fault when accessing old pte. But on x86, there is feature to setting pte access flag by hardware. Hence implement an overriding stub which always returns false. Signed-off-by: Jia He Suggested-by: Will Deacon --- arch/x86/include/asm/pgtable.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 0bc530c4eb13..ad97dc155195 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -1463,6 +1463,12 @@ static inline bool arch_has_pfn_modify_check(void) return boot_cpu_has_bug(X86_BUG_L1TF); } +#define arch_faults_on_old_pte arch_faults_on_old_pte +static inline bool arch_faults_on_old_pte(void) +{ + return false; +} + #include #endif /* __ASSEMBLY__ */ From patchwork Wed Oct 9 08:42:46 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11180809 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3D8DD1709 for ; Wed, 9 Oct 2019 08:43:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 02CC0218AC for ; Wed, 9 Oct 2019 08:43:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02CC0218AC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 373928E0009; Wed, 9 Oct 2019 04:43:34 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 325278E0003; Wed, 9 Oct 2019 04:43:34 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 261698E0009; Wed, 9 Oct 2019 04:43:34 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0167.hostedemail.com [216.40.44.167]) by kanga.kvack.org (Postfix) with ESMTP id 06F838E0003 for ; Wed, 9 Oct 2019 04:43:33 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id C183D40E8 for ; Wed, 9 Oct 2019 08:43:32 +0000 (UTC) X-FDA: 76023607464.25.spade93_58d1659553c15 X-Spam-Summary: 2,0,0,d08ca6257578d572,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:bp@alien8.de:hpa@zytor.com:x86@kernel.org:tglx@linutronix.de:akpm@linux-foundation.org:hejianet@gmail.com:kaly.xin@arm.com:nd@arm.com:justin.he@arm.com,RULES_HIT:2:41:355:379:541:800:960:967:973:988:989:1042:1260:1261:1345:1359:1437:1535:1605:1730:1747:1777:1792:2194:2199:2393:2525:2559:2563:2682:2685:2693:2859:2901:2918:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3865:3866:3867:3868:3870:3871:3872:3873:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4049:4118:4250:4321:4605:5007:6117:6119:6261:6671:6737:7208:7903:8634:8660:9025:9108:10004:11026:11473:11658:11914:12043:12048:12291:12295:12296:12297:12438:12555:12683:12895:12986:13007:13 148:1316 X-HE-Tag: spade93_58d1659553c15 X-Filterd-Recvd-Size: 7685 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 08:43:30 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8F06B1000; Wed, 9 Oct 2019 01:43:29 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id EAD153F68E; Wed, 9 Oct 2019 01:43:24 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org Cc: Thomas Gleixner , Andrew Morton , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v11 4/4] mm: fix double page fault on arm64 if PTE_AF is cleared Date: Wed, 9 Oct 2019 16:42:46 +0800 Message-Id: <20191009084246.123354-5-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191009084246.123354-1-justin.he@arm.com> References: <20191009084246.123354-1-justin.he@arm.com> 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: When we tested pmdk unit test [1] vmmalloc_fork TEST3 on arm64 guest, there will be a double page fault in __copy_from_user_inatomic of cow_user_page. To reproduce the bug, the cmd is as follows after you deployed everything: make -C src/test/vmmalloc_fork/ TEST_TIME=60m check Below call trace is from arm64 do_page_fault for debugging purpose: [ 110.016195] Call trace: [ 110.016826] do_page_fault+0x5a4/0x690 [ 110.017812] do_mem_abort+0x50/0xb0 [ 110.018726] el1_da+0x20/0xc4 [ 110.019492] __arch_copy_from_user+0x180/0x280 [ 110.020646] do_wp_page+0xb0/0x860 [ 110.021517] __handle_mm_fault+0x994/0x1338 [ 110.022606] handle_mm_fault+0xe8/0x180 [ 110.023584] do_page_fault+0x240/0x690 [ 110.024535] do_mem_abort+0x50/0xb0 [ 110.025423] el0_da+0x20/0x24 The pte info before __copy_from_user_inatomic is (PTE_AF is cleared): [ffff9b007000] pgd=000000023d4f8003, pud=000000023da9b003, pmd=000000023d4b3003, pte=360000298607bd3 As told by Catalin: "On arm64 without hardware Access Flag, copying from user will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64." This patch fixes it by calling pte_mkyoung. Also, the parameter is changed because vmf should be passed to cow_user_page() Add a WARN_ON_ONCE when __copy_from_user_inatomic() returns error in case there can be some obscure use-case (by Kirill). [1] https://github.com/pmem/pmdk/tree/master/src/test/vmmalloc_fork Signed-off-by: Jia He Reported-by: Yibo Cai Reviewed-by: Catalin Marinas Acked-by: Kirill A. Shutemov --- mm/memory.c | 104 ++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 89 insertions(+), 15 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index b1ca51a079f2..b6a5d6a08438 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -118,6 +118,18 @@ int randomize_va_space __read_mostly = 2; #endif +#ifndef arch_faults_on_old_pte +static inline bool arch_faults_on_old_pte(void) +{ + /* + * Those arches which don't have hw access flag feature need to + * implement their own helper. By default, "true" means pagefault + * will be hit on old pte. + */ + return true; +} +#endif + static int __init disable_randmaps(char *s) { randomize_va_space = 0; @@ -2145,32 +2157,82 @@ static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, return same; } -static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) +static inline bool cow_user_page(struct page *dst, struct page *src, + struct vm_fault *vmf) { + bool ret; + void *kaddr; + void __user *uaddr; + bool force_mkyoung; + struct vm_area_struct *vma = vmf->vma; + struct mm_struct *mm = vma->vm_mm; + unsigned long addr = vmf->address; + debug_dma_assert_idle(src); + if (likely(src)) { + copy_user_highpage(dst, src, addr, vma); + return true; + } + /* * If the source page was a PFN mapping, we don't have * a "struct page" for it. We do a best-effort copy by * just copying from the original user address. If that * fails, we just zero-fill it. Live with it. */ - if (unlikely(!src)) { - void *kaddr = kmap_atomic(dst); - void __user *uaddr = (void __user *)(va & PAGE_MASK); + kaddr = kmap_atomic(dst); + uaddr = (void __user *)(addr & PAGE_MASK); + + /* + * On architectures with software "accessed" bits, we would + * take a double page fault, so mark it accessed here. + */ + force_mkyoung = arch_faults_on_old_pte() && !pte_young(vmf->orig_pte); + if (force_mkyoung) { + pte_t entry; + + vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); + if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) { + /* + * Other thread has already handled the fault + * and we don't need to do anything. If it's + * not the case, the fault will be triggered + * again on the same address. + */ + ret = false; + goto pte_unlock; + } + entry = pte_mkyoung(vmf->orig_pte); + if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0)) + update_mmu_cache(vma, addr, vmf->pte); + } + + /* + * This really shouldn't fail, because the page is there + * in the page tables. But it might just be unreadable, + * in which case we just give up and fill the result with + * zeroes. + */ + if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { /* - * This really shouldn't fail, because the page is there - * in the page tables. But it might just be unreadable, - * in which case we just give up and fill the result with - * zeroes. + * Give a warn in case there can be some obscure + * use-case */ - if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) - clear_page(kaddr); - kunmap_atomic(kaddr); - flush_dcache_page(dst); - } else - copy_user_highpage(dst, src, va, vma); + WARN_ON_ONCE(1); + clear_page(kaddr); + } + + ret = true; + +pte_unlock: + if (force_mkyoung) + pte_unmap_unlock(vmf->pte, vmf->ptl); + kunmap_atomic(kaddr); + flush_dcache_page(dst); + + return ret; } static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) @@ -2327,7 +2389,19 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) vmf->address); if (!new_page) goto oom; - cow_user_page(new_page, old_page, vmf->address, vma); + + if (!cow_user_page(new_page, old_page, vmf)) { + /* + * COW failed, if the fault was solved by other, + * it's fine. If not, userspace would re-fault on + * the same address and we will handle the fault + * from the second attempt. + */ + put_page(new_page); + if (old_page) + put_page(old_page); + return 0; + } } if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))