diff options
Diffstat (limited to 'include/linux/userfaultfd_k.h')
| -rw-r--r-- | include/linux/userfaultfd_k.h | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h new file mode 100644 index 000000000..9df0b9a76 --- /dev/null +++ b/include/linux/userfaultfd_k.h @@ -0,0 +1,324 @@ +/* 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 int sysctl_unprivileged_userfaultfd; + +extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason); + +/* + * The mode of operation for __mcopy_atomic and its helpers. + * + * This is almost an implementation detail (mcopy_atomic below doesn't take this + * as a parameter), but it's exposed here because memory-kind-specific + * implementations (e.g. hugetlbfs) need to know the mode of operation. + */ +enum mcopy_atomic_mode { + /* A normal copy_from_user into the destination range. */ + MCOPY_ATOMIC_NORMAL, + /* Don't copy; map the destination range to the zero page. */ + MCOPY_ATOMIC_ZEROPAGE, + /* Just install pte(s) with the existing page(s) in the page cache. */ + MCOPY_ATOMIC_CONTINUE, +}; + +extern int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, struct page *page, + bool newly_allocated, bool wp_copy); + +extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, + unsigned long src_start, unsigned long len, + atomic_t *mmap_changing, __u64 mode); +extern ssize_t mfill_zeropage(struct mm_struct *dst_mm, + unsigned long dst_start, + unsigned long len, + atomic_t *mmap_changing); +extern ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long dst_start, + unsigned long len, atomic_t *mmap_changing); +extern int mwriteprotect_range(struct mm_struct *dst_mm, + unsigned long start, unsigned long len, + bool enable_wp, atomic_t *mmap_changing); +extern void uffd_wp_range(struct mm_struct *dst_mm, 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 mm_struct *mm, unsigned long start, + unsigned long end, struct list_head *uf); +extern void userfaultfd_unmap_complete(struct mm_struct *mm, + struct list_head *uf); + +#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 mm_struct *mm, + 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; +} + +#endif /* CONFIG_USERFAULTFD */ + +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 */ |