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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 152F4C433FE for ; Wed, 16 Nov 2022 04:42:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231657AbiKPEmn (ORCPT ); Tue, 15 Nov 2022 23:42:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231617AbiKPEmm (ORCPT ); Tue, 15 Nov 2022 23:42:42 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id F3A3631EC8; Tue, 15 Nov 2022 20:42:40 -0800 (PST) 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 D04E813D5; Tue, 15 Nov 2022 20:42:46 -0800 (PST) Received: from [10.162.40.17] (unknown [10.162.40.17]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AF4D93F73B; Tue, 15 Nov 2022 20:42:37 -0800 (PST) Message-ID: <438ddc78-ded6-d464-f917-6b8749626f16@arm.com> Date: Wed, 16 Nov 2022 10:12:34 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH V2 2/2] arm64: errata: Workaround possible Cortex-A715 [ESR|FAR]_ELx corruption Content-Language: en-US To: Catalin Marinas Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, will@kernel.org, Suzuki K Poulose , James Morse , Jonathan Corbet , Mark Rutland , linux-doc@vger.kernel.org References: <20221113012645.190301-1-anshuman.khandual@arm.com> <20221113012645.190301-3-anshuman.khandual@arm.com> From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 11/15/22 19:32, Catalin Marinas wrote: > On Sun, Nov 13, 2022 at 06:56:45AM +0530, Anshuman Khandual wrote: >> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c >> index 35e9a468d13e..6552947ca7fa 100644 >> --- a/arch/arm64/mm/hugetlbpage.c >> +++ b/arch/arm64/mm/hugetlbpage.c >> @@ -559,3 +559,24 @@ bool __init arch_hugetlb_valid_size(unsigned long size) >> { >> return __hugetlb_valid_size(size); >> } >> + >> +pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) >> +{ >> + if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198)) { >> + pte_t pte = READ_ONCE(*ptep); > > Not sure whether the generated code would be any different but we should > probably add the check for the CPU capability in the 'if' condition > above, before the READ_ONCE (which expands to some asm volatile): Sure, will do. > > if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198) && > cpus_have_const_cap(ARM64_WORKAROUND_2645198)) { > pte_t pte = ... > ... > } The local variable 'pte_t pte' can be dropped as well. > >> + /* >> + * Break-before-make (BBM) is required for all user space mappings >> + * when the permission changes from executable to non-executable >> + * in cases where cpu is affected with errata #2645198. >> + */ >> + if (pte_user_exec(pte) && cpus_have_const_cap(ARM64_WORKAROUND_2645198)) >> + return huge_ptep_clear_flush(vma, addr, ptep); >> + } >> + return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); >> +} >> + >> +void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, >> + pte_t old_pte, pte_t pte) >> +{ >> + set_huge_pte_at(vma->vm_mm, addr, ptep, pte); >> +} >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 9a7c38965154..c1fb0ce1473c 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1702,3 +1702,24 @@ static int __init prevent_bootmem_remove_init(void) >> } >> early_initcall(prevent_bootmem_remove_init); >> #endif >> + >> +pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) >> +{ >> + if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198)) { >> + pte_t pte = READ_ONCE(*ptep); >> + /* >> + * Break-before-make (BBM) is required for all user space mappings >> + * when the permission changes from executable to non-executable >> + * in cases where cpu is affected with errata #2645198. >> + */ >> + if (pte_user_exec(pte) && cpus_have_const_cap(ARM64_WORKAROUND_2645198)) >> + return ptep_clear_flush(vma, addr, ptep); >> + } > > Same here. Sure, will do. > >> + return ptep_get_and_clear(vma->vm_mm, addr, ptep); >> +} >> + >> +void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, >> + pte_t old_pte, pte_t pte) >> +{ >> + __set_pte_at(vma->vm_mm, addr, ptep, pte); >> +} > Planning to apply the following change after this patch. diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 6552947ca7fa..cd8d96e1fa1a 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -562,14 +562,14 @@ bool __init arch_hugetlb_valid_size(unsigned long size) pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { - if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198)) { - pte_t pte = READ_ONCE(*ptep); + if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198) && + cpus_have_const_cap(ARM64_WORKAROUND_2645198)) { /* * Break-before-make (BBM) is required for all user space mappings * when the permission changes from executable to non-executable * in cases where cpu is affected with errata #2645198. */ - if (pte_user_exec(pte) && cpus_have_const_cap(ARM64_WORKAROUND_2645198)) + if (pte_user_exec(READ_ONCE(*ptep))) return huge_ptep_clear_flush(vma, addr, ptep); } return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index c1fb0ce1473c..ec305ea3942c 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1705,14 +1705,14 @@ early_initcall(prevent_bootmem_remove_init); pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { - if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198)) { - pte_t pte = READ_ONCE(*ptep); + if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198) && + cpus_have_const_cap(ARM64_WORKAROUND_2645198)) { /* * Break-before-make (BBM) is required for all user space mappings * when the permission changes from executable to non-executable * in cases where cpu is affected with errata #2645198. */ - if (pte_user_exec(pte) && cpus_have_const_cap(ARM64_WORKAROUND_2645198)) + if (pte_user_exec(READ_ONCE(*ptep))) return ptep_clear_flush(vma, addr, ptep); } return ptep_get_and_clear(vma->vm_mm, addr, ptep);