From ee03645744e3129fb93022bfeb003b89252923ac Mon Sep 17 00:00:00 2001 From: Muhammad Usama Anjum Date: Tue, 3 Jan 2023 12:48:59 +0500 Subject: [PATCH WIP v9 2/4] userfaultfd: split mwriteprotect_range() Split mwriteprotect_range() to create a unlocked version. This will be used in the next patch to write protect a memory area. Add a helper function, wp_range_async() as well. Signed-off-by: Muhammad Usama Anjum --- Changes in v7: - Remove async being set in the PAGEMAP_IOCTL --- fs/userfaultfd.c | 10 +++++++++ include/linux/userfaultfd_k.h | 11 ++++++++++ mm/userfaultfd.c | 40 ++++++++++++++++++++++------------- 3 files changed, 46 insertions(+), 15 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index c17835a0e842..8791a2d371c1 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1961,6 +1961,16 @@ int userfaultfd_wp_async(struct vm_area_struct *vma) return (ctx && (ctx->features & UFFD_FEATURE_WP_ASYNC)); } +int wp_range_async(struct vm_area_struct *vma, unsigned long start, unsigned long len) +{ + struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx; + + if (!ctx) + return -1; + + return __mwriteprotect_range(ctx->mm, start, len, true, &ctx->mmap_changing); +} + static inline unsigned int uffd_ctx_features(__u64 user_features) { /* diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 94dcb4dc1b4a..76407d21d03b 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -73,6 +73,9 @@ extern ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long dst_start, extern int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, unsigned long len, bool enable_wp, 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); @@ -180,6 +183,8 @@ extern int userfaultfd_unmap_prep(struct mm_struct *mm, unsigned long start, extern void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf); extern int userfaultfd_wp_async(struct vm_area_struct *vma); +extern int wp_range_async(struct vm_area_struct *vma, unsigned long start, + unsigned long len); #else /* CONFIG_USERFAULTFD */ @@ -280,6 +285,12 @@ static inline int userfaultfd_wp_async(struct vm_area_struct *vma) return false; } +static inline int wp_range_async(struct vm_area_struct *vma, unsigned long start, + unsigned long len) +{ + return -1; +} + #endif /* CONFIG_USERFAULTFD */ static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 65ad172add27..9d8a43faf764 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -734,25 +734,13 @@ void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, tlb_finish_mmu(&tlb); } -int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, - unsigned long len, bool enable_wp, - atomic_t *mmap_changing) +int __mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, + unsigned long len, bool enable_wp, + atomic_t *mmap_changing) { struct vm_area_struct *dst_vma; unsigned long page_mask; int err; - - /* - * Sanitize the command parameters: - */ - BUG_ON(start & ~PAGE_MASK); - BUG_ON(len & ~PAGE_MASK); - - /* Does the address range wrap, or is the span zero-sized? */ - BUG_ON(start + len <= start); - - mmap_read_lock(dst_mm); - /* * If memory mappings are changing because of non-cooperative * operation (e.g. mremap) running in parallel, bail out and @@ -783,6 +771,28 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, err = 0; out_unlock: + return err; +} + +int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, + unsigned long len, bool enable_wp, + atomic_t *mmap_changing) +{ + int err; + + /* + * Sanitize the command parameters: + */ + BUG_ON(start & ~PAGE_MASK); + BUG_ON(len & ~PAGE_MASK); + + /* Does the address range wrap, or is the span zero-sized? */ + BUG_ON(start + len <= start); + + mmap_read_lock(dst_mm); + + err = __mwriteprotect_range(dst_mm, start, len, enable_wp, mmap_changing); + mmap_read_unlock(dst_mm); return err; } -- 2.30.2