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/* 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);
/* move_pages */
void double_pt_lock(spinlock_t *ptl1, spinlock_t *ptl2);
void double_pt_unlock(spinlock_t *ptl1, spinlock_t *ptl2);
ssize_t move_pages(struct userfaultfd_ctx *ctx, struct mm_struct *mm,
unsigned long dst_start, unsigned long src_start,
unsigned long len, __u64 flags);
int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval,
struct vm_area_struct *dst_vma,
struct vm_area_struct *src_vma,
unsigned long dst_addr, unsigned long src_addr);
/* 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,
bool wp_async)
{
vm_flags &= __VM_UFFD_FLAGS;
if ((vm_flags & VM_UFFD_MINOR) &&
(!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
return false;
/*
* If wp async enabled, and WP is the only mode enabled, allow any
* memory type.
*/
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))
return false;
#endif
/* By default, allow any of anon|shmem|hugetlb */
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);
extern bool userfaultfd_wp_async(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 long uffd_wp_range(struct vm_area_struct *vma,
unsigned long start, unsigned long len,
bool enable_wp)
{
return false;
}
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;
}
static inline bool userfaultfd_wp_async(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 */
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