|  | /* SPDX-License-Identifier: GPL-2.0 */ | 
|  | /* | 
|  | *  include/linux/userfaultfd_k.h | 
|  | * | 
|  | *  Copyright (C) 2015  Red Hat, Inc. | 
|  | * | 
|  | */ | 
|  |  | 
|  | #ifndef _LINUX_USERFAULTFD_K_H | 
|  | #define _LINUX_USERFAULTFD_K_H | 
|  |  | 
|  | #ifdef CONFIG_USERFAULTFD | 
|  |  | 
|  | #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */ | 
|  |  | 
|  | #include <linux/fcntl.h> | 
|  | #include <linux/mm.h> | 
|  | #include <linux/swap.h> | 
|  | #include <linux/swapops.h> | 
|  | #include <asm-generic/pgtable_uffd.h> | 
|  | #include <linux/hugetlb_inline.h> | 
|  |  | 
|  | /* The set of all possible UFFD-related VM flags. */ | 
|  | #define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR) | 
|  |  | 
|  | /* | 
|  | * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining | 
|  | * new flags, since they might collide with O_* ones. We want | 
|  | * to re-use O_* flags that couldn't possibly have a meaning | 
|  | * from userfaultfd, in order to leave a free define-space for | 
|  | * shared O_* flags. | 
|  | */ | 
|  | #define UFFD_CLOEXEC O_CLOEXEC | 
|  | #define UFFD_NONBLOCK O_NONBLOCK | 
|  |  | 
|  | #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) | 
|  | #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS) | 
|  |  | 
|  | extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason); | 
|  |  | 
|  | /* A combined operation mode + behavior flags. */ | 
|  | typedef unsigned int __bitwise uffd_flags_t; | 
|  |  | 
|  | /* Mutually exclusive modes of operation. */ | 
|  | enum mfill_atomic_mode { | 
|  | MFILL_ATOMIC_COPY, | 
|  | MFILL_ATOMIC_ZEROPAGE, | 
|  | MFILL_ATOMIC_CONTINUE, | 
|  | MFILL_ATOMIC_POISON, | 
|  | NR_MFILL_ATOMIC_MODES, | 
|  | }; | 
|  |  | 
|  | #define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1) | 
|  | #define MFILL_ATOMIC_BIT(nr) BIT(MFILL_ATOMIC_MODE_BITS + (nr)) | 
|  | #define MFILL_ATOMIC_FLAG(nr) ((__force uffd_flags_t) MFILL_ATOMIC_BIT(nr)) | 
|  | #define MFILL_ATOMIC_MODE_MASK ((__force uffd_flags_t) (MFILL_ATOMIC_BIT(0) - 1)) | 
|  |  | 
|  | static inline bool uffd_flags_mode_is(uffd_flags_t flags, enum mfill_atomic_mode expected) | 
|  | { | 
|  | return (flags & MFILL_ATOMIC_MODE_MASK) == ((__force uffd_flags_t) expected); | 
|  | } | 
|  |  | 
|  | static inline uffd_flags_t uffd_flags_set_mode(uffd_flags_t flags, enum mfill_atomic_mode mode) | 
|  | { | 
|  | flags &= ~MFILL_ATOMIC_MODE_MASK; | 
|  | return flags | ((__force uffd_flags_t) mode); | 
|  | } | 
|  |  | 
|  | /* Flags controlling behavior. These behavior changes are mode-independent. */ | 
|  | #define MFILL_ATOMIC_WP MFILL_ATOMIC_FLAG(0) | 
|  |  | 
|  | extern int mfill_atomic_install_pte(pmd_t *dst_pmd, | 
|  | struct vm_area_struct *dst_vma, | 
|  | unsigned long dst_addr, struct page *page, | 
|  | bool newly_allocated, uffd_flags_t flags); | 
|  |  | 
|  | extern ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start, | 
|  | unsigned long src_start, unsigned long len, | 
|  | atomic_t *mmap_changing, uffd_flags_t flags); | 
|  | extern ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, | 
|  | unsigned long dst_start, | 
|  | unsigned long len, | 
|  | atomic_t *mmap_changing); | 
|  | extern ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long dst_start, | 
|  | unsigned long len, atomic_t *mmap_changing, | 
|  | uffd_flags_t flags); | 
|  | extern ssize_t mfill_atomic_poison(struct mm_struct *dst_mm, unsigned long start, | 
|  | unsigned long len, atomic_t *mmap_changing, | 
|  | uffd_flags_t flags); | 
|  | extern int mwriteprotect_range(struct mm_struct *dst_mm, | 
|  | unsigned long start, unsigned long len, | 
|  | bool enable_wp, atomic_t *mmap_changing); | 
|  | extern long uffd_wp_range(struct vm_area_struct *vma, | 
|  | unsigned long start, unsigned long len, bool enable_wp); | 
|  |  | 
|  | /* mm helpers */ | 
|  | static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, | 
|  | struct vm_userfaultfd_ctx vm_ctx) | 
|  | { | 
|  | return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx; | 
|  | } | 
|  |  | 
|  | /* | 
|  | * Never enable huge pmd sharing on some uffd registered vmas: | 
|  | * | 
|  | * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry. | 
|  | * | 
|  | * - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for | 
|  | *   VMAs which share huge pmds. (If you have two mappings to the same | 
|  | *   underlying pages, and fault in the non-UFFD-registered one with a write, | 
|  | *   with huge pmd sharing this would *also* setup the second UFFD-registered | 
|  | *   mapping, and we'd not get minor faults.) | 
|  | */ | 
|  | static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma) | 
|  | { | 
|  | return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR); | 
|  | } | 
|  |  | 
|  | /* | 
|  | * Don't do fault around for either WP or MINOR registered uffd range.  For | 
|  | * MINOR registered range, fault around will be a total disaster and ptes can | 
|  | * be installed without notifications; for WP it should mostly be fine as long | 
|  | * as the fault around checks for pte_none() before the installation, however | 
|  | * to be super safe we just forbid it. | 
|  | */ | 
|  | static inline bool uffd_disable_fault_around(struct vm_area_struct *vma) | 
|  | { | 
|  | return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR); | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_missing(struct vm_area_struct *vma) | 
|  | { | 
|  | return vma->vm_flags & VM_UFFD_MISSING; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_wp(struct vm_area_struct *vma) | 
|  | { | 
|  | return vma->vm_flags & VM_UFFD_WP; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_minor(struct vm_area_struct *vma) | 
|  | { | 
|  | return vma->vm_flags & VM_UFFD_MINOR; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma, | 
|  | pte_t pte) | 
|  | { | 
|  | return userfaultfd_wp(vma) && pte_uffd_wp(pte); | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma, | 
|  | pmd_t pmd) | 
|  | { | 
|  | return userfaultfd_wp(vma) && pmd_uffd_wp(pmd); | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_armed(struct vm_area_struct *vma) | 
|  | { | 
|  | return vma->vm_flags & __VM_UFFD_FLAGS; | 
|  | } | 
|  |  | 
|  | static inline bool vma_can_userfault(struct vm_area_struct *vma, | 
|  | unsigned long vm_flags) | 
|  | { | 
|  | if ((vm_flags & VM_UFFD_MINOR) && | 
|  | (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma))) | 
|  | return false; | 
|  | #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)) | 
|  | return false; | 
|  | #endif | 
|  | return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || | 
|  | vma_is_shmem(vma); | 
|  | } | 
|  |  | 
|  | extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *); | 
|  | extern void dup_userfaultfd_complete(struct list_head *); | 
|  |  | 
|  | extern void mremap_userfaultfd_prep(struct vm_area_struct *, | 
|  | struct vm_userfaultfd_ctx *); | 
|  | extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *, | 
|  | unsigned long from, unsigned long to, | 
|  | unsigned long len); | 
|  |  | 
|  | extern bool userfaultfd_remove(struct vm_area_struct *vma, | 
|  | unsigned long start, | 
|  | unsigned long end); | 
|  |  | 
|  | extern int userfaultfd_unmap_prep(struct vm_area_struct *vma, | 
|  | unsigned long start, unsigned long end, struct list_head *uf); | 
|  | extern void userfaultfd_unmap_complete(struct mm_struct *mm, | 
|  | struct list_head *uf); | 
|  | extern bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma); | 
|  |  | 
|  | #else /* CONFIG_USERFAULTFD */ | 
|  |  | 
|  | /* mm helpers */ | 
|  | static inline vm_fault_t handle_userfault(struct vm_fault *vmf, | 
|  | unsigned long reason) | 
|  | { | 
|  | return VM_FAULT_SIGBUS; | 
|  | } | 
|  |  | 
|  | static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, | 
|  | struct vm_userfaultfd_ctx vm_ctx) | 
|  | { | 
|  | return true; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_missing(struct vm_area_struct *vma) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_wp(struct vm_area_struct *vma) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_minor(struct vm_area_struct *vma) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma, | 
|  | pte_t pte) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma, | 
|  | pmd_t pmd) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  |  | 
|  | static inline bool userfaultfd_armed(struct vm_area_struct *vma) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  | static inline int dup_userfaultfd(struct vm_area_struct *vma, | 
|  | struct list_head *l) | 
|  | { | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | static inline void dup_userfaultfd_complete(struct list_head *l) | 
|  | { | 
|  | } | 
|  |  | 
|  | static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma, | 
|  | struct vm_userfaultfd_ctx *ctx) | 
|  | { | 
|  | } | 
|  |  | 
|  | static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx, | 
|  | unsigned long from, | 
|  | unsigned long to, | 
|  | unsigned long len) | 
|  | { | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_remove(struct vm_area_struct *vma, | 
|  | unsigned long start, | 
|  | unsigned long end) | 
|  | { | 
|  | return true; | 
|  | } | 
|  |  | 
|  | static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma, | 
|  | unsigned long start, unsigned long end, | 
|  | struct list_head *uf) | 
|  | { | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | static inline void userfaultfd_unmap_complete(struct mm_struct *mm, | 
|  | struct list_head *uf) | 
|  | { | 
|  | } | 
|  |  | 
|  | static inline bool uffd_disable_fault_around(struct vm_area_struct *vma) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  | static inline bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma) | 
|  | { | 
|  | return false; | 
|  | } | 
|  |  | 
|  | #endif /* CONFIG_USERFAULTFD */ | 
|  |  | 
|  | static inline bool userfaultfd_wp_use_markers(struct vm_area_struct *vma) | 
|  | { | 
|  | /* Only wr-protect mode uses pte markers */ | 
|  | if (!userfaultfd_wp(vma)) | 
|  | return false; | 
|  |  | 
|  | /* File-based uffd-wp always need markers */ | 
|  | if (!vma_is_anonymous(vma)) | 
|  | return true; | 
|  |  | 
|  | /* | 
|  | * Anonymous uffd-wp only needs the markers if WP_UNPOPULATED | 
|  | * enabled (to apply markers on zero pages). | 
|  | */ | 
|  | return userfaultfd_wp_unpopulated(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); | 
|  | #else | 
|  | return false; | 
|  | #endif | 
|  | } | 
|  |  | 
|  | static inline bool pte_marker_uffd_wp(pte_t pte) | 
|  | { | 
|  | #ifdef CONFIG_PTE_MARKER_UFFD_WP | 
|  | swp_entry_t entry; | 
|  |  | 
|  | if (!is_swap_pte(pte)) | 
|  | return false; | 
|  |  | 
|  | entry = pte_to_swp_entry(pte); | 
|  |  | 
|  | return pte_marker_entry_uffd_wp(entry); | 
|  | #else | 
|  | return false; | 
|  | #endif | 
|  | } | 
|  |  | 
|  | /* | 
|  | * Returns true if this is a swap pte and was uffd-wp wr-protected in either | 
|  | * forms (pte marker or a normal swap pte), false otherwise. | 
|  | */ | 
|  | 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 (pte_swp_uffd_wp(pte)) | 
|  | return true; | 
|  |  | 
|  | if (pte_marker_uffd_wp(pte)) | 
|  | return true; | 
|  | #endif | 
|  | return false; | 
|  | } | 
|  |  | 
|  | #endif /* _LINUX_USERFAULTFD_K_H */ |