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 A766EC4829E for ; Thu, 15 Feb 2024 11:27:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 32E966B00A0; Thu, 15 Feb 2024 06:27:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B90C6B00A1; Thu, 15 Feb 2024 06:27:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 10B348D0001; Thu, 15 Feb 2024 06:27:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id ED8F06B00A0 for ; Thu, 15 Feb 2024 06:27:17 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id B35EB120FD2 for ; Thu, 15 Feb 2024 11:27:17 +0000 (UTC) X-FDA: 81793812114.30.755BE99 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf17.hostedemail.com (Postfix) with ESMTP id CBE774001A for ; Thu, 15 Feb 2024 11:27:15 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf17.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1707996435; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wbdo8hp8qCFiPpPcNSH46ue6smPGFYzylB6zw9oFRnI=; b=sSsJVPovj11c7SLscjV2bLIcA03BCm1KQjUznx8gGC3zLKThgC/qQyMb4posLwcX2lqda1 3Si1SzT5/R3LsekUIiHS0MEJ9x701KHgU2DPAIXDwhlNq0tTfOZGdnMkx0sArEXuHwZOe+ ax0Q6o8ck3U4imGWChEJXQO7iSUGVWk= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf17.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1707996435; a=rsa-sha256; cv=none; b=Srk4jMZlFJOtcq+/5CfxUVfYy5pRADkvPFM9IhVHF0SkOmelQU7/O2dqsA+QGi8TiRjAlm xjkDtfd7yCOdaKz7I4lJotJF5fAMkFWhyruH1V0Dc0au/cT+NOqAcH84OKWfHdGz+NGGVa g3OIbx0Y7iwOOZgR0QRp8T6G74pJrO4= 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 C9132DA7; Thu, 15 Feb 2024 03:27:55 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.68.11]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 54E8D3F7B4; Thu, 15 Feb 2024 03:27:11 -0800 (PST) Date: Thu, 15 Feb 2024 11:27:07 +0000 From: Mark Rutland To: Ryan Roberts Cc: Catalin Marinas , Will Deacon , Ard Biesheuvel , Marc Zyngier , James Morse , Andrey Ryabinin , Andrew Morton , Matthew Wilcox , David Hildenbrand , Kefeng Wang , John Hubbard , Zi Yan , Barry Song <21cnbao@gmail.com>, Alistair Popple , Yang Shi , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 12/18] arm64/mm: Wire up PTE_CONT for user mappings Message-ID: References: <20240215103205.2607016-1-ryan.roberts@arm.com> <20240215103205.2607016-13-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240215103205.2607016-13-ryan.roberts@arm.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: CBE774001A X-Stat-Signature: q1qn56s1f9cbbr13bf7secmjehoufroi X-Rspam-User: X-HE-Tag: 1707996435-351500 X-HE-Meta: U2FsdGVkX1+d64g+8PLuoB6aoBKP49Z8HdP04siohYhQWgcnjU8gAqUY2Tnk/F5TJunWRieatCfQj1gYAMKJzd7Pu+wWMzhSu0Rwxm13pjZd21AjpK8UzR8E2aTj19WefpIBptD6nepXcwlMgyox5bFTV1zWFs4j6of/tKrpTRZ7n6DdrRTGUJN4oOwQkXWM+gOnAPz4tvrHO9Cf10ABpufv2Opu649r1GfbGuHR7y7Xr9o6xY1G533PxCi+GkVEgacwZFXAdsWMrFs1op3ns+HqUK3UrLMhuLhqWgbGexfPJiVbWqEPfTSbess40dn5RNYH3NnxRBV23JyUPRI0E3wNgWVQvwIVNzurWbaYklqDlbPhB7uClTGnzjs5+uhW8fMaW/XSp5tkRjvSbNrJx4D/JizLyrZunkTM4HopY87resrFsjxKdZY7bsf30fdOWHDhMCxVh45fabaErCbRqEsTdHXAB4sxUu1OZEf0AW01lPDA57n1h07Ff4xj7OAgNjigIpw69UxRu2gL6yReOWAQcQ+PbCrXrUkRhViLMArcKkMC2cgENy5shyq12w87KrB8BouifUTr9RT9cwrx23WbGbddzZArjeaituQHM968mInYeHxOWtqJ3wDDq9Vpi6bD7PElJMDccpkKAx6czu/CR0WlAlOfuMON0kYccSJ0R57CbyPlTt+pxFdg3D+quxmRnIMSzmrveQ6qtGpdi+hW0XhzBZ/G7gojePlhE+nXnbtbyeD29qAuaeQ7Ak+lDasGVE1Uy8M7F8hvNluWUKgTt5YnPqMV4Gr9WNtFXBDj7qOUybANOLWIpMpu5kISSiDLydYLk5GMR4CCQHoknSv6Tegd1Xwn0wipkQqO2Cg8Ya1KJOkcCPh4yTy0hVDLgFiAw4IBKoser1N4spEi4Mex/Iwq+xMB0tA4ZHmp0WcwpdP3Z85FIg1kGu4nB4GQ0piqSeZcFjwBGAmUqVs vOY6k3+j U56gEnglDRhTQOs0SOYid2LWbs8JyLafUrC5U1NO9PhDbrmMmgzQ03gQv90CD3qwM7etAJGAs3NTNueKnXxhBhjuXY2gsyIyuhvcbbGEZEjwbkjhfdtqkgkoewljP1aQBcsIOtZ7aE7QHEorq6UIl0l7D2WnLH7JtwlJiWN/6jvWYMWQrORDLv0eFeJEB7997OTzLzN33uJOBw08kULJxaw6VuJ6bmU72cSOHzkhubc9Ud7y9sKNnmKTQuvapIvKbsQH7kifOqPX4KUa0qU+g4N5sSZDKO3GorFz6e69uQqloPmd46htu6xkVZ8K1aeQJpBXX4Svu+/rhxHV31nZEEBUeRwbg0Go8Hk33j8PQf09tyP/DD0nwyLc/yw== 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: List-Subscribe: List-Unsubscribe: On Thu, Feb 15, 2024 at 10:31:59AM +0000, Ryan Roberts wrote: > With the ptep API sufficiently refactored, we can now introduce a new > "contpte" API layer, which transparently manages the PTE_CONT bit for > user mappings. > > In this initial implementation, only suitable batches of PTEs, set via > set_ptes(), are mapped with the PTE_CONT bit. Any subsequent > modification of individual PTEs will cause an "unfold" operation to > repaint the contpte block as individual PTEs before performing the > requested operation. While, a modification of a single PTE could cause > the block of PTEs to which it belongs to become eligible for "folding" > into a contpte entry, "folding" is not performed in this initial > implementation due to the costs of checking the requirements are met. > Due to this, contpte mappings will degrade back to normal pte mappings > over time if/when protections are changed. This will be solved in a > future patch. > > Since a contpte block only has a single access and dirty bit, the > semantic here changes slightly; when getting a pte (e.g. ptep_get()) > that is part of a contpte mapping, the access and dirty information are > pulled from the block (so all ptes in the block return the same > access/dirty info). When changing the access/dirty info on a pte (e.g. > ptep_set_access_flags()) that is part of a contpte mapping, this change > will affect the whole contpte block. This is works fine in practice > since we guarantee that only a single folio is mapped by a contpte > block, and the core-mm tracks access/dirty information per folio. > > In order for the public functions, which used to be pure inline, to > continue to be callable by modules, export all the contpte_* symbols > that are now called by those public inline functions. > > The feature is enabled/disabled with the ARM64_CONTPTE Kconfig parameter > at build time. It defaults to enabled as long as its dependency, > TRANSPARENT_HUGEPAGE is also enabled. The core-mm depends upon > TRANSPARENT_HUGEPAGE to be able to allocate large folios, so if its not > enabled, then there is no chance of meeting the physical contiguity > requirement for contpte mappings. > > Acked-by: Ard Biesheuvel > Tested-by: John Hubbard > Signed-off-by: Ryan Roberts Acked-by: Mark Rutland Mark. > --- > arch/arm64/Kconfig | 9 + > arch/arm64/include/asm/pgtable.h | 167 ++++++++++++++++++ > arch/arm64/mm/Makefile | 1 + > arch/arm64/mm/contpte.c | 285 +++++++++++++++++++++++++++++++ > include/linux/efi.h | 5 + > 5 files changed, 467 insertions(+) > create mode 100644 arch/arm64/mm/contpte.c > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index e8275a40afbd..5a7ac1f37bdc 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -2229,6 +2229,15 @@ config UNWIND_PATCH_PAC_INTO_SCS > select UNWIND_TABLES > select DYNAMIC_SCS > > +config ARM64_CONTPTE > + bool "Contiguous PTE mappings for user memory" if EXPERT > + depends on TRANSPARENT_HUGEPAGE > + default y > + help > + When enabled, user mappings are configured using the PTE contiguous > + bit, for any mappings that meet the size and alignment requirements. > + This reduces TLB pressure and improves performance. > + > endmenu # "Kernel Features" > > menu "Boot options" > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 7336d40a893a..831099cfc96b 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -133,6 +133,10 @@ static inline pteval_t __phys_to_pte_val(phys_addr_t phys) > */ > #define pte_valid_not_user(pte) \ > ((pte_val(pte) & (PTE_VALID | PTE_USER | PTE_UXN)) == (PTE_VALID | PTE_UXN)) > +/* > + * Returns true if the pte is valid and has the contiguous bit set. > + */ > +#define pte_valid_cont(pte) (pte_valid(pte) && pte_cont(pte)) > /* > * Could the pte be present in the TLB? We must check mm_tlb_flush_pending > * so that we don't erroneously return false for pages that have been > @@ -1128,6 +1132,167 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma, > unsigned long addr, pte_t *ptep, > pte_t old_pte, pte_t new_pte); > > +#ifdef CONFIG_ARM64_CONTPTE > + > +/* > + * The contpte APIs are used to transparently manage the contiguous bit in ptes > + * where it is possible and makes sense to do so. The PTE_CONT bit is considered > + * a private implementation detail of the public ptep API (see below). > + */ > +extern void __contpte_try_unfold(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte); > +extern pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte); > +extern pte_t contpte_ptep_get_lockless(pte_t *orig_ptep); > +extern void contpte_set_ptes(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte, unsigned int nr); > +extern int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep); > +extern int contpte_ptep_clear_flush_young(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep); > +extern int contpte_ptep_set_access_flags(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + pte_t entry, int dirty); > + > +static inline void contpte_try_unfold(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte) > +{ > + if (unlikely(pte_valid_cont(pte))) > + __contpte_try_unfold(mm, addr, ptep, pte); > +} > + > +/* > + * The below functions constitute the public API that arm64 presents to the > + * core-mm to manipulate PTE entries within their page tables (or at least this > + * is the subset of the API that arm64 needs to implement). These public > + * versions will automatically and transparently apply the contiguous bit where > + * it makes sense to do so. Therefore any users that are contig-aware (e.g. > + * hugetlb, kernel mapper) should NOT use these APIs, but instead use the > + * private versions, which are prefixed with double underscore. All of these > + * APIs except for ptep_get_lockless() are expected to be called with the PTL > + * held. Although the contiguous bit is considered private to the > + * implementation, it is deliberately allowed to leak through the getters (e.g. > + * ptep_get()), back to core code. This is required so that pte_leaf_size() can > + * provide an accurate size for perf_get_pgtable_size(). But this leakage means > + * its possible a pte will be passed to a setter with the contiguous bit set, so > + * we explicitly clear the contiguous bit in those cases to prevent accidentally > + * setting it in the pgtable. > + */ > + > +#define ptep_get ptep_get > +static inline pte_t ptep_get(pte_t *ptep) > +{ > + pte_t pte = __ptep_get(ptep); > + > + if (likely(!pte_valid_cont(pte))) > + return pte; > + > + return contpte_ptep_get(ptep, pte); > +} > + > +#define ptep_get_lockless ptep_get_lockless > +static inline pte_t ptep_get_lockless(pte_t *ptep) > +{ > + pte_t pte = __ptep_get(ptep); > + > + if (likely(!pte_valid_cont(pte))) > + return pte; > + > + return contpte_ptep_get_lockless(ptep); > +} > + > +static inline void set_pte(pte_t *ptep, pte_t pte) > +{ > + /* > + * We don't have the mm or vaddr so cannot unfold contig entries (since > + * it requires tlb maintenance). set_pte() is not used in core code, so > + * this should never even be called. Regardless do our best to service > + * any call and emit a warning if there is any attempt to set a pte on > + * top of an existing contig range. > + */ > + pte_t orig_pte = __ptep_get(ptep); > + > + WARN_ON_ONCE(pte_valid_cont(orig_pte)); > + __set_pte(ptep, pte_mknoncont(pte)); > +} > + > +#define set_ptes set_ptes > +static inline void set_ptes(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte, unsigned int nr) > +{ > + pte = pte_mknoncont(pte); > + > + if (likely(nr == 1)) { > + contpte_try_unfold(mm, addr, ptep, __ptep_get(ptep)); > + __set_ptes(mm, addr, ptep, pte, 1); > + } else { > + contpte_set_ptes(mm, addr, ptep, pte, nr); > + } > +} > + > +static inline void pte_clear(struct mm_struct *mm, > + unsigned long addr, pte_t *ptep) > +{ > + contpte_try_unfold(mm, addr, ptep, __ptep_get(ptep)); > + __pte_clear(mm, addr, ptep); > +} > + > +#define __HAVE_ARCH_PTEP_GET_AND_CLEAR > +static inline pte_t ptep_get_and_clear(struct mm_struct *mm, > + unsigned long addr, pte_t *ptep) > +{ > + contpte_try_unfold(mm, addr, ptep, __ptep_get(ptep)); > + return __ptep_get_and_clear(mm, addr, ptep); > +} > + > +#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG > +static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep) > +{ > + pte_t orig_pte = __ptep_get(ptep); > + > + if (likely(!pte_valid_cont(orig_pte))) > + return __ptep_test_and_clear_young(vma, addr, ptep); > + > + return contpte_ptep_test_and_clear_young(vma, addr, ptep); > +} > + > +#define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH > +static inline int ptep_clear_flush_young(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep) > +{ > + pte_t orig_pte = __ptep_get(ptep); > + > + if (likely(!pte_valid_cont(orig_pte))) > + return __ptep_clear_flush_young(vma, addr, ptep); > + > + return contpte_ptep_clear_flush_young(vma, addr, ptep); > +} > + > +#define __HAVE_ARCH_PTEP_SET_WRPROTECT > +static inline void ptep_set_wrprotect(struct mm_struct *mm, > + unsigned long addr, pte_t *ptep) > +{ > + contpte_try_unfold(mm, addr, ptep, __ptep_get(ptep)); > + __ptep_set_wrprotect(mm, addr, ptep); > +} > + > +#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS > +static inline int ptep_set_access_flags(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + pte_t entry, int dirty) > +{ > + pte_t orig_pte = __ptep_get(ptep); > + > + entry = pte_mknoncont(entry); > + > + if (likely(!pte_valid_cont(orig_pte))) > + return __ptep_set_access_flags(vma, addr, ptep, entry, dirty); > + > + return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirty); > +} > + > +#else /* CONFIG_ARM64_CONTPTE */ > + > #define ptep_get __ptep_get > #define set_pte __set_pte > #define set_ptes __set_ptes > @@ -1143,6 +1308,8 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma, > #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS > #define ptep_set_access_flags __ptep_set_access_flags > > +#endif /* CONFIG_ARM64_CONTPTE */ > + > #endif /* !__ASSEMBLY__ */ > > #endif /* __ASM_PGTABLE_H */ > diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile > index dbd1bc95967d..60454256945b 100644 > --- a/arch/arm64/mm/Makefile > +++ b/arch/arm64/mm/Makefile > @@ -3,6 +3,7 @@ obj-y := dma-mapping.o extable.o fault.o init.o \ > cache.o copypage.o flush.o \ > ioremap.o mmap.o pgd.o mmu.o \ > context.o proc.o pageattr.o fixmap.o > +obj-$(CONFIG_ARM64_CONTPTE) += contpte.o > obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o > obj-$(CONFIG_PTDUMP_CORE) += ptdump.o > obj-$(CONFIG_PTDUMP_DEBUGFS) += ptdump_debugfs.o > diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c > new file mode 100644 > index 000000000000..6d7f40667fa2 > --- /dev/null > +++ b/arch/arm64/mm/contpte.c > @@ -0,0 +1,285 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2023 ARM Ltd. > + */ > + > +#include > +#include > +#include > +#include > + > +static inline bool mm_is_user(struct mm_struct *mm) > +{ > + /* > + * Don't attempt to apply the contig bit to kernel mappings, because > + * dynamically adding/removing the contig bit can cause page faults. > + * These racing faults are ok for user space, since they get serialized > + * on the PTL. But kernel mappings can't tolerate faults. > + */ > + if (unlikely(mm_is_efi(mm))) > + return false; > + return mm != &init_mm; > +} > + > +static inline pte_t *contpte_align_down(pte_t *ptep) > +{ > + return PTR_ALIGN_DOWN(ptep, sizeof(*ptep) * CONT_PTES); > +} > + > +static void contpte_convert(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte) > +{ > + struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0); > + unsigned long start_addr; > + pte_t *start_ptep; > + int i; > + > + start_ptep = ptep = contpte_align_down(ptep); > + start_addr = addr = ALIGN_DOWN(addr, CONT_PTE_SIZE); > + pte = pfn_pte(ALIGN_DOWN(pte_pfn(pte), CONT_PTES), pte_pgprot(pte)); > + > + for (i = 0; i < CONT_PTES; i++, ptep++, addr += PAGE_SIZE) { > + pte_t ptent = __ptep_get_and_clear(mm, addr, ptep); > + > + if (pte_dirty(ptent)) > + pte = pte_mkdirty(pte); > + > + if (pte_young(ptent)) > + pte = pte_mkyoung(pte); > + } > + > + __flush_tlb_range(&vma, start_addr, addr, PAGE_SIZE, true, 3); > + > + __set_ptes(mm, start_addr, start_ptep, pte, CONT_PTES); > +} > + > +void __contpte_try_unfold(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte) > +{ > + /* > + * We have already checked that the ptes are contiguous in > + * contpte_try_unfold(), so just check that the mm is user space. > + */ > + if (!mm_is_user(mm)) > + return; > + > + pte = pte_mknoncont(pte); > + contpte_convert(mm, addr, ptep, pte); > +} > +EXPORT_SYMBOL(__contpte_try_unfold); > + > +pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte) > +{ > + /* > + * Gather access/dirty bits, which may be populated in any of the ptes > + * of the contig range. We are guaranteed to be holding the PTL, so any > + * contiguous range cannot be unfolded or otherwise modified under our > + * feet. > + */ > + > + pte_t pte; > + int i; > + > + ptep = contpte_align_down(ptep); > + > + for (i = 0; i < CONT_PTES; i++, ptep++) { > + pte = __ptep_get(ptep); > + > + if (pte_dirty(pte)) > + orig_pte = pte_mkdirty(orig_pte); > + > + if (pte_young(pte)) > + orig_pte = pte_mkyoung(orig_pte); > + } > + > + return orig_pte; > +} > +EXPORT_SYMBOL(contpte_ptep_get); > + > +pte_t contpte_ptep_get_lockless(pte_t *orig_ptep) > +{ > + /* > + * Gather access/dirty bits, which may be populated in any of the ptes > + * of the contig range. We may not be holding the PTL, so any contiguous > + * range may be unfolded/modified/refolded under our feet. Therefore we > + * ensure we read a _consistent_ contpte range by checking that all ptes > + * in the range are valid and have CONT_PTE set, that all pfns are > + * contiguous and that all pgprots are the same (ignoring access/dirty). > + * If we find a pte that is not consistent, then we must be racing with > + * an update so start again. If the target pte does not have CONT_PTE > + * set then that is considered consistent on its own because it is not > + * part of a contpte range. > + */ > + > + pgprot_t orig_prot; > + unsigned long pfn; > + pte_t orig_pte; > + pgprot_t prot; > + pte_t *ptep; > + pte_t pte; > + int i; > + > +retry: > + orig_pte = __ptep_get(orig_ptep); > + > + if (!pte_valid_cont(orig_pte)) > + return orig_pte; > + > + orig_prot = pte_pgprot(pte_mkold(pte_mkclean(orig_pte))); > + ptep = contpte_align_down(orig_ptep); > + pfn = pte_pfn(orig_pte) - (orig_ptep - ptep); > + > + for (i = 0; i < CONT_PTES; i++, ptep++, pfn++) { > + pte = __ptep_get(ptep); > + prot = pte_pgprot(pte_mkold(pte_mkclean(pte))); > + > + if (!pte_valid_cont(pte) || > + pte_pfn(pte) != pfn || > + pgprot_val(prot) != pgprot_val(orig_prot)) > + goto retry; > + > + if (pte_dirty(pte)) > + orig_pte = pte_mkdirty(orig_pte); > + > + if (pte_young(pte)) > + orig_pte = pte_mkyoung(orig_pte); > + } > + > + return orig_pte; > +} > +EXPORT_SYMBOL(contpte_ptep_get_lockless); > + > +void contpte_set_ptes(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte, unsigned int nr) > +{ > + unsigned long next; > + unsigned long end; > + unsigned long pfn; > + pgprot_t prot; > + > + /* > + * The set_ptes() spec guarantees that when nr > 1, the initial state of > + * all ptes is not-present. Therefore we never need to unfold or > + * otherwise invalidate a range before we set the new ptes. > + * contpte_set_ptes() should never be called for nr < 2. > + */ > + VM_WARN_ON(nr == 1); > + > + if (!mm_is_user(mm)) > + return __set_ptes(mm, addr, ptep, pte, nr); > + > + end = addr + (nr << PAGE_SHIFT); > + pfn = pte_pfn(pte); > + prot = pte_pgprot(pte); > + > + do { > + next = pte_cont_addr_end(addr, end); > + nr = (next - addr) >> PAGE_SHIFT; > + pte = pfn_pte(pfn, prot); > + > + if (((addr | next | (pfn << PAGE_SHIFT)) & ~CONT_PTE_MASK) == 0) > + pte = pte_mkcont(pte); > + else > + pte = pte_mknoncont(pte); > + > + __set_ptes(mm, addr, ptep, pte, nr); > + > + addr = next; > + ptep += nr; > + pfn += nr; > + > + } while (addr != end); > +} > +EXPORT_SYMBOL(contpte_set_ptes); > + > +int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep) > +{ > + /* > + * ptep_clear_flush_young() technically requires us to clear the access > + * flag for a _single_ pte. However, the core-mm code actually tracks > + * access/dirty per folio, not per page. And since we only create a > + * contig range when the range is covered by a single folio, we can get > + * away with clearing young for the whole contig range here, so we avoid > + * having to unfold. > + */ > + > + int young = 0; > + int i; > + > + ptep = contpte_align_down(ptep); > + addr = ALIGN_DOWN(addr, CONT_PTE_SIZE); > + > + for (i = 0; i < CONT_PTES; i++, ptep++, addr += PAGE_SIZE) > + young |= __ptep_test_and_clear_young(vma, addr, ptep); > + > + return young; > +} > +EXPORT_SYMBOL(contpte_ptep_test_and_clear_young); > + > +int contpte_ptep_clear_flush_young(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep) > +{ > + int young; > + > + young = contpte_ptep_test_and_clear_young(vma, addr, ptep); > + > + if (young) { > + /* > + * See comment in __ptep_clear_flush_young(); same rationale for > + * eliding the trailing DSB applies here. > + */ > + addr = ALIGN_DOWN(addr, CONT_PTE_SIZE); > + __flush_tlb_range_nosync(vma, addr, addr + CONT_PTE_SIZE, > + PAGE_SIZE, true, 3); > + } > + > + return young; > +} > +EXPORT_SYMBOL(contpte_ptep_clear_flush_young); > + > +int contpte_ptep_set_access_flags(struct vm_area_struct *vma, > + unsigned long addr, pte_t *ptep, > + pte_t entry, int dirty) > +{ > + unsigned long start_addr; > + pte_t orig_pte; > + int i; > + > + /* > + * Gather the access/dirty bits for the contiguous range. If nothing has > + * changed, its a noop. > + */ > + orig_pte = pte_mknoncont(ptep_get(ptep)); > + if (pte_val(orig_pte) == pte_val(entry)) > + return 0; > + > + /* > + * We can fix up access/dirty bits without having to unfold the contig > + * range. But if the write bit is changing, we must unfold. > + */ > + if (pte_write(orig_pte) == pte_write(entry)) { > + /* > + * For HW access management, we technically only need to update > + * the flag on a single pte in the range. But for SW access > + * management, we need to update all the ptes to prevent extra > + * faults. Avoid per-page tlb flush in __ptep_set_access_flags() > + * and instead flush the whole range at the end. > + */ > + ptep = contpte_align_down(ptep); > + start_addr = addr = ALIGN_DOWN(addr, CONT_PTE_SIZE); > + > + for (i = 0; i < CONT_PTES; i++, ptep++, addr += PAGE_SIZE) > + __ptep_set_access_flags(vma, addr, ptep, entry, 0); > + > + if (dirty) > + __flush_tlb_range(vma, start_addr, addr, > + PAGE_SIZE, true, 3); > + } else { > + __contpte_try_unfold(vma->vm_mm, addr, ptep, orig_pte); > + __ptep_set_access_flags(vma, addr, ptep, entry, dirty); > + } > + > + return 1; > +} > +EXPORT_SYMBOL(contpte_ptep_set_access_flags); > diff --git a/include/linux/efi.h b/include/linux/efi.h > index c74f47711f0b..57da15e7429c 100644 > --- a/include/linux/efi.h > +++ b/include/linux/efi.h > @@ -692,6 +692,11 @@ extern struct efi { > > extern struct mm_struct efi_mm; > > +static inline bool mm_is_efi(struct mm_struct *mm) > +{ > + return IS_ENABLED(CONFIG_EFI) && mm == &efi_mm; > +} > + > static inline int > efi_guidcmp (efi_guid_t left, efi_guid_t right) > { > -- > 2.25.1 >