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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1443BC433ED for ; Mon, 17 May 2021 12:33:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB02561261 for ; Mon, 17 May 2021 12:33:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235165AbhEQMed (ORCPT ); Mon, 17 May 2021 08:34:33 -0400 Received: from foss.arm.com ([217.140.110.172]:50080 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234654AbhEQMec (ORCPT ); Mon, 17 May 2021 08:34:32 -0400 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 E29C5139F; Mon, 17 May 2021 05:33:15 -0700 (PDT) Received: from e112269-lin.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E0B943F73B; Mon, 17 May 2021 05:33:12 -0700 (PDT) From: Steven Price To: Catalin Marinas , Marc Zyngier , Will Deacon Cc: Steven Price , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Dave Martin , Mark Rutland , Thomas Gleixner , qemu-devel@nongnu.org, Juan Quintela , "Dr. David Alan Gilbert" , Richard Henderson , Peter Maydell , Haibo Xu , Andrew Jones Subject: [PATCH v12 2/8] arm64: Handle MTE tags zeroing in __alloc_zeroed_user_highpage() Date: Mon, 17 May 2021 13:32:33 +0100 Message-Id: <20210517123239.8025-3-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210517123239.8025-1-steven.price@arm.com> References: <20210517123239.8025-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Catalin Marinas Currently, on an anonymous page fault, the kernel allocates a zeroed page and maps it in user space. If the mapping is tagged (PROT_MTE), set_pte_at() additionally clears the tags under a spinlock to avoid a race on the page->flags. In order to optimise the lock, clear the page tags on allocation in __alloc_zeroed_user_highpage() if the vma flags have VM_MTE set. Signed-off-by: Catalin Marinas Signed-off-by: Steven Price --- arch/arm64/include/asm/page.h | 6 ++++-- arch/arm64/mm/fault.c | 21 +++++++++++++++++++++ 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h index 012cffc574e8..97853570d0f1 100644 --- a/arch/arm64/include/asm/page.h +++ b/arch/arm64/include/asm/page.h @@ -13,6 +13,7 @@ #ifndef __ASSEMBLY__ #include /* for READ_IMPLIES_EXEC */ +#include #include struct page; @@ -28,8 +29,9 @@ void copy_user_highpage(struct page *to, struct page *from, void copy_highpage(struct page *to, struct page *from); #define __HAVE_ARCH_COPY_HIGHPAGE -#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \ - alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr) +struct page *__alloc_zeroed_user_highpage(gfp_t movableflags, + struct vm_area_struct *vma, + unsigned long vaddr); #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE #define clear_user_page(page, vaddr, pg) clear_page(page) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 871c82ab0a30..5a03428e97f3 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -921,3 +921,24 @@ void do_debug_exception(unsigned long addr_if_watchpoint, unsigned int esr, debug_exception_exit(regs); } NOKPROBE_SYMBOL(do_debug_exception); + +/* + * Used during anonymous page fault handling. + */ +struct page *__alloc_zeroed_user_highpage(gfp_t movableflags, + struct vm_area_struct *vma, + unsigned long vaddr) +{ + struct page *page; + bool tagged = system_supports_mte() && (vma->vm_flags & VM_MTE); + + page = alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, + vaddr); + if (tagged && page) { + mte_clear_page_tags(page_address(page)); + page_kasan_tag_reset(page); + set_bit(PG_mte_tagged, &page->flags); + } + + return page; +} -- 2.20.1