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_ctx *ctx, if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) vm_flags |= 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 |= 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 &= ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); #endif -#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP - uffdio_api.features &= ~UFFD_FEATURE_PAGEFAULT_FLAG_WP; -#endif -#ifndef CONFIG_PTE_MARKER_UFFD_WP - uffdio_api.features &= ~UFFD_FEATURE_WP_HUGETLBFS_SHMEM; - uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED; - uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC; -#endif + if (!pgtable_uffd_wp_supported()) + uffdio_api.features &= ~UFFD_FEATURE_PAGEFAULT_FLAG_WP; + + if (!IS_ENABLED(CONFIG_PTE_MARKER_UFFD_WP) || + !pgtable_uffd_wp_supported()) { + uffdio_api.features &= ~UFFD_FEATURE_WP_HUGETLBFS_SHMEM; + uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED; + uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC; + } ret = -EINVAL; if (features & ~uffdio_api.features) diff --git a/include/asm-generic/pgtable_uffd.h b/include/asm-generic/pgtable_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 +/* + * 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_USERFAULTFD_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 *vma, 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 = false; /* 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_struct *vma, if (wp_async && (vm_flags == VM_UFFD_WP)) return true; -#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 /* 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 vm_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; - if (!is_swap_pte(pte)) - return false; + if (!is_swap_pte(pte)) + return false; - entry = pte_to_swp_entry(pte); + entry = pte_to_swp_entry(pte); + + return pte_marker_entry_uffd_wp(entry); + } else { + return false; + } - 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; - if (pte_swp_uffd_wp(pte)) - return true; + if (pte_swp_uffd_wp(pte)) + return true; - 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 = false; -#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 += PAGE_SIZE; } -#endif + return was_installed; } -- 2.34.1