From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7ACE33B3C15 for ; Mon, 20 Jul 2026 06:55:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784530531; cv=none; b=mObEtIeBEbAmk4b/f71ywqH9Mh5xjr7hCo82p7HA14SNHbo2mJMGYzD5IdJFs9Yz0bD3MT23vZqmgl7bLkxWHOc3Hmh7YVrGAI4hZkVEwlcO/iCRGNFKdsX0kTnKmmhqO/pozCHfp9mc211q8ay4XX2WUs8ma8JEHg5XPJhYh2Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784530531; c=relaxed/simple; bh=x+kolBURkoz37XH2+zAgPHsgQcy0+7m0YaymnTdJ0PI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=t8QuC/tfjAupfllNqix/ZFcVzsrCoBehWgyj0/K5dyk7YTkxcfaGTBYTQNJOZag1Cf/xYl6acOsOqCgkP+7+PHCiP0eIZB7WRWatRais0VWgylecn/nZdyrrSGL0EMo4SRw6SnR4+kGcMiOrG7XA25N81DT7AwHR8ejtwQqS5Y0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=Qaff0VTp; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="Qaff0VTp" 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 3E8031516; Sun, 19 Jul 2026 23:55:24 -0700 (PDT) Received: from cesw-amp-gbt-1s-m12830-01.blr.arm.com (cesw-amp-gbt-1s-m12830-01.blr.arm.com [10.164.195.33]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4F27E3F66F; Sun, 19 Jul 2026 23:55:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784530528; bh=x+kolBURkoz37XH2+zAgPHsgQcy0+7m0YaymnTdJ0PI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Qaff0VTprT/uptOom7N3m2o1wCp0o+NkCLqF5iaRvywGvdKWuFND+F0Pw1SF9HkcK 4sBQbnSEonmOtBPVtMQEGBXOPhYrB8lc8E8ijTlnnb7yULC0xYsop13Q4+CtKl3q+e 1rLTJnWy7LNGkaZLACiWro5kMo3Ygm8x9XolWf8c= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, riel@surriel.com, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH v2 1/3] mm/memory: move pte_install_uffd_wp_if_needed() into memory.c Date: Mon, 20 Jul 2026 06:55:05 +0000 Message-ID: <20260720065508.2695106-2-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260720065508.2695106-1-dev.jain@arm.com> References: <20260720065508.2695106-1-dev.jain@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit pte_install_uffd_wp_if_needed() has grown too large for mm_inline.h. Move it to memory.c. This helper is only used inside mm/, so declare it in mm/internal.h instead of a public header. While at it, convert the comment to kerneldoc and rename the local arguments from pte/pteval to ptep/pte so the pointer and PTE value are easier to distinguish. Signed-off-by: Dev Jain --- include/linux/mm_inline.h | 53 ---------------------------------- mm/internal.h | 3 ++ mm/memory.c | 60 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 63 insertions(+), 53 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index b5c4dc0f3fe32..621c8653d8f7e 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -566,59 +566,6 @@ static inline pte_marker copy_pte_marker( return dstm; } -/* - * If this pte is wr-protected by uffd-wp in any form, arm the special pte to - * replace a none pte. NOTE! This should only be called when *pte is already - * cleared so we will never accidentally replace something valuable. Meanwhile - * none pte also means we are not demoting the pte so tlb flushed is not needed. - * E.g., when pte cleared the caller should have taken care of the tlb flush. - * - * Must be called with pgtable lock held so that no thread will see the none - * pte, and if they see it, they'll fault and serialize at the pgtable lock. - * - * Returns true if an uffd-wp pte was installed, false otherwise. - */ -static inline bool -pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, - pte_t *pte, pte_t pteval) -{ - bool arm_uffd_pte = false; - - if (!uffd_supports_wp_marker()) - return false; - - /* The current status of the pte should be "cleared" before calling */ - WARN_ON_ONCE(!pte_none(ptep_get(pte))); - - /* - * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole - * thing, because when zapping either it means it's dropping the - * page, or in TTU where the present pte will be quickly replaced - * with a swap pte. There's no way of leaking the bit. - */ - if (vma_is_anonymous(vma) || !userfaultfd_wp(vma)) - return false; - - /* A uffd-wp wr-protected normal pte */ - if (unlikely(pte_present(pteval) && pte_uffd(pteval))) - arm_uffd_pte = true; - - /* - * A uffd-wp wr-protected swap pte. Note: this should even cover an - * existing pte marker with uffd-wp bit set. - */ - if (unlikely(pte_swp_uffd_any(pteval))) - arm_uffd_pte = true; - - if (unlikely(arm_uffd_pte)) { - set_pte_at(vma->vm_mm, addr, pte, - make_pte_marker(PTE_MARKER_UFFD_WP)); - return true; - } - - return false; -} - static inline bool vma_has_recency(const struct vm_area_struct *vma) { if (vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ)) diff --git a/mm/internal.h b/mm/internal.h index f26423de4ca28..b6a3589a61c1a 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -276,6 +276,9 @@ void unmap_vmas(struct mmu_gather *tlb, struct unmap_desc *unmap); #ifdef CONFIG_MMU +bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte); + static inline void get_anon_vma(struct anon_vma *anon_vma) { atomic_inc(&anon_vma->refcount); diff --git a/mm/memory.c b/mm/memory.c index d5e87624f6920..6c0c4c774674a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1675,6 +1675,66 @@ static inline bool zap_drop_markers(struct zap_details *details) return details->zap_flags & ZAP_FLAG_DROP_MARKER; } +/** + * pte_install_uffd_wp_if_needed - install uffd-wp marker after clearing a PTE + * @vma: The VMA the page is mapped into. + * @addr: Address the page is mapped at. + * @ptep: Page table pointer for this entry. + * @pte: Old value of the entry pointed to by @ptep. + * + * If the PTE was write-protected by uffd-wp in any form, arm a special PTE + * to replace a none PTE. NOTE! This should only be called when the PTE is + * already cleared so we will never accidentally replace something valuable. + * Meanwhile none PTEs also mean we are not demoting the PTE so a TLB flush is + * not needed. E.g., when the PTE was cleared, the caller should have taken care + * of the TLB flush. + * + * Must be called with the page table lock held so that no thread will see the + * none PTE, and if they see it, they'll fault and serialize at the page table + * lock. + * + * Returns true if an uffd-wp PTE was installed, false otherwise. + */ +bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte) +{ + bool arm_uffd_pte = false; + + if (!uffd_supports_wp_marker()) + return false; + + /* The current status of the pte should be "cleared" before calling */ + WARN_ON_ONCE(!pte_none(ptep_get(ptep))); + + /* + * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole + * thing, because when zapping either it means it's dropping the + * page, or in TTU where the present pte will be quickly replaced + * with a swap pte. There's no way of leaking the bit. + */ + if (vma_is_anonymous(vma) || !userfaultfd_wp(vma)) + return false; + + /* A uffd-wp wr-protected normal pte */ + if (unlikely(pte_present(pte) && pte_uffd(pte))) + arm_uffd_pte = true; + + /* + * A uffd-wp wr-protected swap pte. Note: this should even cover an + * existing pte marker with uffd-wp bit set. + */ + if (unlikely(pte_swp_uffd_any(pte))) + arm_uffd_pte = true; + + if (unlikely(arm_uffd_pte)) { + set_pte_at(vma->vm_mm, addr, ptep, + make_pte_marker(PTE_MARKER_UFFD_WP)); + return true; + } + + return false; +} + /* * This function makes sure that we'll replace the none pte with an uffd-wp * swap special pte marker when necessary. Must be with the pgtable lock held. -- 2.43.0