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(unknown [210.73.43.101]) by APP-03 (Coremail) with SMTP id rQCowACH2IK5nMJoo6pCAg--.44660S4; Thu, 11 Sep 2025 17:56:12 +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 v11 2/5] mm: userfaultfd: Add pgtable_uffd_wp_supported() Date: Thu, 11 Sep 2025 17:55:59 +0800 Message-Id: <20250911095602.1130290-3-zhangchunyan@iscas.ac.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250911095602.1130290-1-zhangchunyan@iscas.ac.cn> References: <20250911095602.1130290-1-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: rQCowACH2IK5nMJoo6pCAg--.44660S4 X-Coremail-Antispam: 1UD129KBjvJXoW3Gr1DGFWrJry3KryfWF17ZFb_yoWxuFyfpF 47Gw45Xrs7JF97Ga93Aa10k3s8Zw4fKrykWryF93W8A3W3t390vryFkFWFyF93Jr4kWryx tF17trWkur42vwUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmmb7Iv0xC_KF4lb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI 8067AKxVWUXwA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF 64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcV CY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv 6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c 02F40Ex7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVW8JVWxJwAm72CE 4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7 CjxVAaw2AFwI0_GFv_Wrylc2xSY4AK67AK6r4fMxAIw28IcxkI7VAKI48JMxC20s026xCa FVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_Jr Wlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j 6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWxJVW8Jr1lIxAIcVCF04k26cxKx2IYs7xG6r 1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1U YxBIdaVFxhVjvjDU0xZFpf9x07jPID7UUUUU= X-CM-SenderInfo: x2kd0wxfkx051dq6x2xfdvhtffof0/1tbiDAgCB2jCjVc9QgAAsO 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 --- fs/userfaultfd.c | 23 ++++++++-------- include/asm-generic/pgtable_uffd.h | 11 ++++++++ include/linux/mm_inline.h | 7 +++++ include/linux/userfaultfd_k.h | 44 +++++++++++++++++++----------- mm/memory.c | 6 ++-- 5 files changed, 62 insertions(+), 29 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 54c6cc7fe9c6..b549c327d7ad 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_uffd_wp_supported()) + goto out; + vm_flags |=3D VM_UFFD_WP; } if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR) { @@ -1980,14 +1980,15 @@ 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_uffd_wp_supported()) + uffdio_api.features &=3D ~UFFD_FEATURE_PAGEFAULT_FLAG_WP; + + if (!IS_ENABLED(CONFIG_PTE_MARKER_UFFD_WP) || + !pgtable_uffd_wp_supported()) { + 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..895d68ece0e7 100644 --- a/include/asm-generic/pgtable_uffd.h +++ b/include/asm-generic/pgtable_uffd.h @@ -1,6 +1,17 @@ #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 overiding it, please make sure the + * CONFIG_HAVE_ARCH_USERFAULTFD_WP is part of this macro. + */ +#ifndef pgtable_uffd_wp_supported +#define pgtable_uffd_wp_supported() IS_ENABLED(CONFIG_HAVE_ARCH_USERFAULTF= D_WP) +#endif #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..38845b8b79ff 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -571,6 +571,13 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *v= ma, unsigned long addr, pte_t *pte, pte_t pteval) { #ifdef CONFIG_PTE_MARKER_UFFD_WP + /* + * Some platforms can customize the PTE uffd-wp bit, making it unavailable + * even if the architecture allows providing the PTE resource. + */ + if (!pgtable_uffd_wp_supported()) + return false; + bool arm_uffd_pte =3D false; =20 /* The current status of the pte should be "cleared" before calling */ diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index c0e716aec26a..6264b56ae961 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -228,15 +228,15 @@ 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 ((!IS_ENABLED(CONFIG_PTE_MARKER_UFFD_WP) || + !pgtable_uffd_wp_supported()) && + (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) || @@ -437,8 +437,11 @@ static inline bool userfaultfd_wp_use_markers(struct v= m_area_struct *vma) static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry) { #ifdef CONFIG_PTE_MARKER_UFFD_WP - return is_pte_marker_entry(entry) && - (pte_marker_get(entry) & PTE_MARKER_UFFD_WP); + if (pgtable_uffd_wp_supported()) + return is_pte_marker_entry(entry) && + (pte_marker_get(entry) & PTE_MARKER_UFFD_WP); + else + return false; #else return false; #endif @@ -447,14 +450,19 @@ static inline bool pte_marker_entry_uffd_wp(swp_entry= _t entry) static inline bool pte_marker_uffd_wp(pte_t pte) { #ifdef CONFIG_PTE_MARKER_UFFD_WP - swp_entry_t entry; + if (pgtable_uffd_wp_supported()) { + swp_entry_t entry; =20 - if (!is_swap_pte(pte)) - return false; + if (!is_swap_pte(pte)) + return false; =20 - entry =3D pte_to_swp_entry(pte); + entry =3D pte_to_swp_entry(pte); + + return pte_marker_entry_uffd_wp(entry); + } else { + return false; + } =20 - return pte_marker_entry_uffd_wp(entry); #else return false; #endif @@ -467,14 +475,18 @@ 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 (!is_swap_pte(pte)) - return false; + if (pgtable_uffd_wp_supported()) { + if (!is_swap_pte(pte)) + return false; =20 - if (pte_swp_uffd_wp(pte)) - return true; + if (pte_swp_uffd_wp(pte)) + return true; =20 - if (pte_marker_uffd_wp(pte)) - return true; + if (pte_marker_uffd_wp(pte)) + return true; + } else { + return false; + } #endif return false; } diff --git a/mm/memory.c b/mm/memory.c index 0ba4f6b71847..4eb05c5f487b 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 (!IS_ENABLED(CONFIG_PTE_MARKER_UFFD_WP) || !pgtable_uffd_wp_supported(= )) + 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