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(unknown [210.73.43.101]) by APP-05 (Coremail) with SMTP id zQCowAD3lxHf5sdoHWn3Ag--.53429S4; Mon, 15 Sep 2025 18:13:55 +0800 (CST) From: Chunyan Zhang To: linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Deepak Gupta , Ved Shanbhogue , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Peter Xu , Arnd Bergmann , David Hildenbrand , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Axel Rasmussen , Yuanchu Xie , Chunyan Zhang Subject: [PATCH V12 2/5] mm: userfaultfd: Add pgtable_supports_uffd_wp() Date: Mon, 15 Sep 2025 18:13:40 +0800 Message-Id: <20250915101343.1449546-3-zhangchunyan@iscas.ac.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250915101343.1449546-1-zhangchunyan@iscas.ac.cn> References: <20250915101343.1449546-1-zhangchunyan@iscas.ac.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zQCowAD3lxHf5sdoHWn3Ag--.53429S4 X-Coremail-Antispam: 1UD129KBjvJXoW3Gr1DGFWrJr1DWr15Xw15XFb_yoWxZFyUpF 4rGw43Xw4ktF97Ga93JF48C3s8Zw4xGFyDGryF9a18A3W3t39YvFyFkF1rKr97Jr4kWry3 tF17trZ3Cr42vF7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmvb7Iv0xC_KF4lb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI 8067AKxVWUXwA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF 64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcV CY1x0267AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIE c7CjxVAFwI0_GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I 8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r4j6F4UMcvjeVCF s4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x 0262kKe7AKxVW8ZVWrXwCY02Avz4vE14v_Gw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC 6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWw C2zVAF1VAY17CE14v26r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_ JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY6xAIw20EY4v20xvaj40_Jr 0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUv cSsGvfC2KfnxnUUI43ZEXa7IUnaXdUUUUUU== X-CM-SenderInfo: x2kd0wxfkx051dq6x2xfdvhtffof0/1tbiCRAGB2jHtda7WAAAs3 Content-Type: text/plain; charset="utf-8" Some platforms can customize the PTE/PMD entry uffd-wp bit making it unavailable even if the architecture provides the resource. This patch adds a macro API that allows architectures to define their specific implementations to check if the uffd-wp bit is available on which device the kernel is running. Signed-off-by: Chunyan Zhang Acked-by: David Hildenbrand --- fs/userfaultfd.c | 22 +++++++++++----------- include/asm-generic/pgtable_uffd.h | 17 +++++++++++++++++ include/linux/mm_inline.h | 10 ++++++++-- include/linux/userfaultfd_k.h | 27 +++++++++++++-------------- mm/memory.c | 6 ++++-- 5 files changed, 53 insertions(+), 29 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 54c6cc7fe9c6..e41736ffa202 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1270,9 +1270,9 @@ static int userfaultfd_register(struct userfaultfd_ct= x *ctx, if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) vm_flags |=3D VM_UFFD_MISSING; if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { -#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP - goto out; -#endif + if (!pgtable_supports_uffd_wp()) + goto out; + vm_flags |=3D VM_UFFD_WP; } if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR) { @@ -1980,14 +1980,14 @@ static int userfaultfd_api(struct userfaultfd_ctx *= ctx, uffdio_api.features &=3D ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); #endif -#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP - uffdio_api.features &=3D ~UFFD_FEATURE_PAGEFAULT_FLAG_WP; -#endif -#ifndef CONFIG_PTE_MARKER_UFFD_WP - uffdio_api.features &=3D ~UFFD_FEATURE_WP_HUGETLBFS_SHMEM; - uffdio_api.features &=3D ~UFFD_FEATURE_WP_UNPOPULATED; - uffdio_api.features &=3D ~UFFD_FEATURE_WP_ASYNC; -#endif + if (!pgtable_supports_uffd_wp()) + uffdio_api.features &=3D ~UFFD_FEATURE_PAGEFAULT_FLAG_WP; + + if (!uffd_supports_wp_marker()) { + uffdio_api.features &=3D ~UFFD_FEATURE_WP_HUGETLBFS_SHMEM; + uffdio_api.features &=3D ~UFFD_FEATURE_WP_UNPOPULATED; + uffdio_api.features &=3D ~UFFD_FEATURE_WP_ASYNC; + } =20 ret =3D -EINVAL; if (features & ~uffdio_api.features) diff --git a/include/asm-generic/pgtable_uffd.h b/include/asm-generic/pgtab= le_uffd.h index 828966d4c281..200da65262a8 100644 --- a/include/asm-generic/pgtable_uffd.h +++ b/include/asm-generic/pgtable_uffd.h @@ -1,6 +1,23 @@ #ifndef _ASM_GENERIC_PGTABLE_UFFD_H #define _ASM_GENERIC_PGTABLE_UFFD_H =20 +/* + * Some platforms can customize the uffd-wp bit, making it unavailable + * even if the architecture provides the resource. + * Adding this API allows architectures to add their own checks for the + * devices on which the kernel is running. + * Note: When overriding it, please make sure the + * CONFIG_HAVE_ARCH_USERFAULTFD_WP is part of this macro. + */ +#ifndef pgtable_supports_uffd_wp +#define pgtable_supports_uffd_wp() IS_ENABLED(CONFIG_HAVE_ARCH_USERFAULTFD= _WP) +#endif + +static __always_inline bool uffd_supports_wp_marker(void) +{ + return pgtable_supports_uffd_wp() && IS_ENABLED(CONFIG_PTE_MARKER_UFFD_WP= ); +} + #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP static __always_inline int pte_uffd_wp(pte_t pte) { diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 89b518ff097e..d6526a7f034b 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -570,9 +570,15 @@ static inline bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long ad= dr, pte_t *pte, pte_t pteval) { -#ifdef CONFIG_PTE_MARKER_UFFD_WP bool arm_uffd_pte =3D false; =20 + /* + * Some platforms can customize the PTE uffd-wp bit, making it unavailable + * even if the architecture allows providing the PTE resource. + */ + 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))); =20 @@ -601,7 +607,7 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *vm= a, unsigned long addr, make_pte_marker(PTE_MARKER_UFFD_WP)); return true; } -#endif + return false; } =20 diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index c0e716aec26a..c19435863076 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -228,15 +228,14 @@ static inline bool vma_can_userfault(struct vm_area_s= truct *vma, if (wp_async && (vm_flags =3D=3D VM_UFFD_WP)) return true; =20 -#ifndef CONFIG_PTE_MARKER_UFFD_WP /* * If user requested uffd-wp but not enabled pte markers for * uffd-wp, then shmem & hugetlbfs are not supported but only * anonymous. */ - if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma)) + if (!uffd_supports_wp_marker() && (vm_flags & VM_UFFD_WP) && + !vma_is_anonymous(vma)) return false; -#endif =20 /* By default, allow any of anon|shmem|hugetlb */ return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || @@ -436,28 +435,26 @@ static inline bool userfaultfd_wp_use_markers(struct = vm_area_struct *vma) =20 static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry) { -#ifdef CONFIG_PTE_MARKER_UFFD_WP + if (!uffd_supports_wp_marker()) + return false; + return is_pte_marker_entry(entry) && - (pte_marker_get(entry) & PTE_MARKER_UFFD_WP); -#else - return false; -#endif + (pte_marker_get(entry) & PTE_MARKER_UFFD_WP); } =20 static inline bool pte_marker_uffd_wp(pte_t pte) { -#ifdef CONFIG_PTE_MARKER_UFFD_WP swp_entry_t entry; =20 + if (!uffd_supports_wp_marker()) + return false; + if (!is_swap_pte(pte)) return false; =20 entry =3D pte_to_swp_entry(pte); =20 return pte_marker_entry_uffd_wp(entry); -#else - return false; -#endif } =20 /* @@ -466,7 +463,9 @@ static inline bool pte_marker_uffd_wp(pte_t pte) */ static inline bool pte_swp_uffd_wp_any(pte_t pte) { -#ifdef CONFIG_PTE_MARKER_UFFD_WP + if (!uffd_supports_wp_marker()) + return false; + if (!is_swap_pte(pte)) return false; =20 @@ -475,7 +474,7 @@ static inline bool pte_swp_uffd_wp_any(pte_t pte) =20 if (pte_marker_uffd_wp(pte)) return true; -#endif + return false; } =20 diff --git a/mm/memory.c b/mm/memory.c index 0ba4f6b71847..607e14177412 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1465,7 +1465,9 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *= vma, { bool was_installed =3D false; =20 -#ifdef CONFIG_PTE_MARKER_UFFD_WP + if (!uffd_supports_wp_marker()) + return false; + /* Zap on anonymous always means dropping everything */ if (vma_is_anonymous(vma)) return false; @@ -1482,7 +1484,7 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *= vma, pte++; addr +=3D PAGE_SIZE; } -#endif + return was_installed; } =20 --=20 2.34.1