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imf22.hostedemail.com; dkim=none; spf=pass (imf22.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752829407; a=rsa-sha256; cv=none; b=MFqDCRROOvIQzOYUQ2tjb3r0lPHcEwK52of01LdBW2LrwVDM/9/nQE1ILnBoMdydBv0hg9 mumn7NveiTHNuLQOthcCno6aael1qYoJ/CRKlN1ku0HL4NLaNmnEjFlekasPDWoA9BfLa5 hSAkymDI/ikyQtbPsHmZlSrLi/vWw7w= 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 AEF8B176C; Fri, 18 Jul 2025 02:03:18 -0700 (PDT) Received: from MacBook-Pro.blr.arm.com (unknown [10.164.18.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 094223F66E; Fri, 18 Jul 2025 02:03:17 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org Cc: ryan.roberts@arm.com, david@redhat.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com, anshuman.khandual@arm.com, peterx@redhat.com, joey.gouly@arm.com, ioworker0@gmail.com, baohua@kernel.org, kevin.brodsky@arm.com, quic_zhenhuah@quicinc.com, christophe.leroy@csgroup.eu, yangyicong@hisilicon.com, linux-arm-kernel@lists.infradead.org, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com, Dev Jain Subject: [PATCH v5 3/7] mm: Add batched versions of ptep_modify_prot_start/commit Date: Fri, 18 Jul 2025 14:32:40 +0530 Message-Id: <20250718090244.21092-4-dev.jain@arm.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250718090244.21092-1-dev.jain@arm.com> References: <20250718090244.21092-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: EECF2C0006 X-Rspamd-Server: rspam06 X-Stat-Signature: 1tq6i6dyt9np1ooyua4n5nbhseqr75b8 X-HE-Tag: 1752829406-461591 X-HE-Meta: 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 XLPIBwDq qPftp21xjgS48hMUNALdyH3pfyXquV7DIHQYX8z7ArN08A5uKgxGGe5u8PGnD1j52g5diw6AtyRmczC18EVB4xfj1BFHRtFIsCMsKle2se9FBFzxovHv8vZHpiCKvVG5A+BOyJHCoRdMAj1GfczxQx01nmkRpUZpizinhy1voaHAGwYgp++oV9PQM9Lm1nCbYpTSLtyFq/tej5sriX2mwod7ozMkXYWdQNhZuDBOwQ+pxfG8= 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: Batch ptep_modify_prot_start/commit in preparation for optimizing mprotect, implementing them as a simple loop over the corresponding single pte helpers. Architecture may override these helpers. Signed-off-by: Dev Jain --- include/linux/pgtable.h | 84 ++++++++++++++++++++++++++++++++++++++++- mm/mprotect.c | 4 +- 2 files changed, 85 insertions(+), 3 deletions(-) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index cf1515c163e2..e3b99920be05 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1331,7 +1331,9 @@ static inline pte_t ptep_modify_prot_start(struct vm_area_struct *vma, /* * Commit an update to a pte, leaving any hardware-controlled bits in - * the PTE unmodified. + * the PTE unmodified. The pte returned from ptep_modify_prot_start() may + * additionally have young and/or dirty bits set where previously they were not, + * so the updated pte may have these additional changes. */ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, @@ -1340,6 +1342,86 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma, __ptep_modify_prot_commit(vma, addr, ptep, pte); } #endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */ + +/** + * modify_prot_start_ptes - Start a pte protection read-modify-write transaction + * over a batch of ptes, which protects against asynchronous hardware + * modifications to the ptes. The intention is not to prevent the hardware from + * making pte updates, but to prevent any updates it may make from being lost. + * Please see the comment above ptep_modify_prot_start() for full description. + * + * @vma: The virtual memory area the pages are mapped into. + * @addr: Address the first page is mapped at. + * @ptep: Page table pointer for the first entry. + * @nr: Number of entries. + * + * May be overridden by the architecture; otherwise, implemented as a simple + * loop over ptep_modify_prot_start(), collecting the a/d bits from each pte + * in the batch. + * + * Note that PTE bits in the PTE batch besides the PFN can differ. + * + * Context: The caller holds the page table lock. The PTEs map consecutive + * pages that belong to the same folio. All other PTE bits must be identical for + * all PTEs in the batch except for young and dirty bits. The PTEs are all in + * the same PMD. + */ +#ifndef modify_prot_start_ptes +static inline pte_t modify_prot_start_ptes(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, unsigned int nr) +{ + pte_t pte, tmp_pte; + + pte = ptep_modify_prot_start(vma, addr, ptep); + while (--nr) { + ptep++; + addr += PAGE_SIZE; + tmp_pte = ptep_modify_prot_start(vma, addr, ptep); + if (pte_dirty(tmp_pte)) + pte = pte_mkdirty(pte); + if (pte_young(tmp_pte)) + pte = pte_mkyoung(pte); + } + return pte; +} +#endif + +/** + * modify_prot_commit_ptes - Commit an update to a batch of ptes, leaving any + * hardware-controlled bits in the PTE unmodified. + * + * @vma: The virtual memory area the pages are mapped into. + * @addr: Address the first page is mapped at. + * @ptep: Page table pointer for the first entry. + * @old_pte: Old page table entry (for the first entry) which is now cleared. + * @pte: New page table entry to be set. + * @nr: Number of entries. + * + * May be overridden by the architecture; otherwise, implemented as a simple + * loop over ptep_modify_prot_commit(). + * + * Context: The caller holds the page table lock. The PTEs are all in the same + * PMD. On exit, the set ptes in the batch map the same folio. The ptes set by + * ptep_modify_prot_start() may additionally have young and/or dirty bits set + * where previously they were not, so the updated ptes may have these + * additional changes. + */ +#ifndef modify_prot_commit_ptes +static inline void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr, + pte_t *ptep, pte_t old_pte, pte_t pte, unsigned int nr) +{ + int i; + + for (i = 0; i < nr; ++i, ++ptep, addr += PAGE_SIZE) { + ptep_modify_prot_commit(vma, addr, ptep, old_pte, pte); + + /* Advance PFN only, set same prot */ + old_pte = pte_next_pfn(old_pte); + pte = pte_next_pfn(pte); + } +} +#endif + #endif /* CONFIG_MMU */ /* diff --git a/mm/mprotect.c b/mm/mprotect.c index 97adc62c50ab..4977f198168e 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -204,7 +204,7 @@ static long change_pte_range(struct mmu_gather *tlb, } } - oldpte = ptep_modify_prot_start(vma, addr, pte); + oldpte = modify_prot_start_ptes(vma, addr, pte, nr_ptes); ptent = pte_modify(oldpte, newprot); if (uffd_wp) @@ -230,7 +230,7 @@ static long change_pte_range(struct mmu_gather *tlb, can_change_pte_writable(vma, addr, ptent)) ptent = pte_mkwrite(ptent, vma); - ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); + modify_prot_commit_ptes(vma, addr, pte, oldpte, ptent, nr_ptes); if (pte_needs_flush(oldpte, ptent)) tlb_flush_pte_range(tlb, addr, PAGE_SIZE); pages++; -- 2.30.2