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![Peter Xu](/assets/img/avatar_default.png)
We've had all the necessary changes ready for both shmem and hugetlbfs. Turn on all the shmem/hugetlbfs switches for userfaultfd-wp. We can expand UFFD_API_RANGE_IOCTLS_BASIC with _UFFDIO_WRITEPROTECT too because all existing types now support write protection mode. Since vma_can_userfault() will be used elsewhere, move into userfaultfd_k.h. Link: https://lkml.kernel.org/r/20220405014926.15101-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
764 lines
18 KiB
C
764 lines
18 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/userfaultfd.c
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*
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* Copyright (C) 2015 Red Hat, Inc.
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*/
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#include <linux/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/pagemap.h>
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#include <linux/rmap.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/mmu_notifier.h>
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#include <linux/hugetlb.h>
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#include <linux/shmem_fs.h>
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#include <asm/tlbflush.h>
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#include <asm/tlb.h>
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#include "internal.h"
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static __always_inline
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struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm,
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unsigned long dst_start,
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unsigned long len)
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{
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/*
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* Make sure that the dst range is both valid and fully within a
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* single existing vma.
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*/
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struct vm_area_struct *dst_vma;
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dst_vma = find_vma(dst_mm, dst_start);
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if (!dst_vma)
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return NULL;
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if (dst_start < dst_vma->vm_start ||
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dst_start + len > dst_vma->vm_end)
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return NULL;
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/*
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* Check the vma is registered in uffd, this is required to
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* enforce the VM_MAYWRITE check done at uffd registration
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* time.
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*/
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if (!dst_vma->vm_userfaultfd_ctx.ctx)
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return NULL;
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return dst_vma;
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}
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/*
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* Install PTEs, to map dst_addr (within dst_vma) to page.
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*
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* This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem
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* and anon, and for both shared and private VMAs.
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*/
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int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr, struct page *page,
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bool newly_allocated, bool wp_copy)
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{
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int ret;
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pte_t _dst_pte, *dst_pte;
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bool writable = dst_vma->vm_flags & VM_WRITE;
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bool vm_shared = dst_vma->vm_flags & VM_SHARED;
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bool page_in_cache = page->mapping;
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spinlock_t *ptl;
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struct inode *inode;
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pgoff_t offset, max_off;
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_dst_pte = mk_pte(page, dst_vma->vm_page_prot);
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_dst_pte = pte_mkdirty(_dst_pte);
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if (page_in_cache && !vm_shared)
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writable = false;
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/*
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* Always mark a PTE as write-protected when needed, regardless of
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* VM_WRITE, which the user might change.
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*/
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if (wp_copy) {
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_dst_pte = pte_mkuffd_wp(_dst_pte);
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writable = false;
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}
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if (writable)
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_dst_pte = pte_mkwrite(_dst_pte);
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else
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/*
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* We need this to make sure write bit removed; as mk_pte()
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* could return a pte with write bit set.
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*/
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_dst_pte = pte_wrprotect(_dst_pte);
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dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
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if (vma_is_shmem(dst_vma)) {
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/* serialize against truncate with the page table lock */
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inode = dst_vma->vm_file->f_inode;
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offset = linear_page_index(dst_vma, dst_addr);
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max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
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ret = -EFAULT;
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if (unlikely(offset >= max_off))
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goto out_unlock;
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}
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ret = -EEXIST;
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/*
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* We allow to overwrite a pte marker: consider when both MISSING|WP
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* registered, we firstly wr-protect a none pte which has no page cache
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* page backing it, then access the page.
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*/
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if (!pte_none_mostly(*dst_pte))
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goto out_unlock;
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if (page_in_cache) {
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/* Usually, cache pages are already added to LRU */
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if (newly_allocated)
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lru_cache_add(page);
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page_add_file_rmap(page, dst_vma, false);
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} else {
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page_add_new_anon_rmap(page, dst_vma, dst_addr);
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lru_cache_add_inactive_or_unevictable(page, dst_vma);
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}
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/*
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* Must happen after rmap, as mm_counter() checks mapping (via
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* PageAnon()), which is set by __page_set_anon_rmap().
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*/
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inc_mm_counter(dst_mm, mm_counter(page));
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set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
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/* No need to invalidate - it was non-present before */
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update_mmu_cache(dst_vma, dst_addr, dst_pte);
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ret = 0;
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out_unlock:
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pte_unmap_unlock(dst_pte, ptl);
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return ret;
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}
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static int mcopy_atomic_pte(struct mm_struct *dst_mm,
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pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr,
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unsigned long src_addr,
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struct page **pagep,
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bool wp_copy)
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{
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void *page_kaddr;
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int ret;
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struct page *page;
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if (!*pagep) {
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ret = -ENOMEM;
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page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);
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if (!page)
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goto out;
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page_kaddr = kmap_atomic(page);
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ret = copy_from_user(page_kaddr,
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(const void __user *) src_addr,
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PAGE_SIZE);
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kunmap_atomic(page_kaddr);
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/* fallback to copy_from_user outside mmap_lock */
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if (unlikely(ret)) {
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ret = -ENOENT;
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*pagep = page;
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/* don't free the page */
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goto out;
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}
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flush_dcache_page(page);
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} else {
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page = *pagep;
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*pagep = NULL;
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}
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/*
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* The memory barrier inside __SetPageUptodate makes sure that
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* preceding stores to the page contents become visible before
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* the set_pte_at() write.
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*/
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__SetPageUptodate(page);
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ret = -ENOMEM;
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if (mem_cgroup_charge(page_folio(page), dst_mm, GFP_KERNEL))
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goto out_release;
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ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
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page, true, wp_copy);
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if (ret)
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goto out_release;
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out:
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return ret;
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out_release:
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put_page(page);
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goto out;
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}
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static int mfill_zeropage_pte(struct mm_struct *dst_mm,
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pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr)
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{
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pte_t _dst_pte, *dst_pte;
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spinlock_t *ptl;
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int ret;
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pgoff_t offset, max_off;
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struct inode *inode;
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_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
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dst_vma->vm_page_prot));
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dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
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if (dst_vma->vm_file) {
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/* the shmem MAP_PRIVATE case requires checking the i_size */
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inode = dst_vma->vm_file->f_inode;
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offset = linear_page_index(dst_vma, dst_addr);
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max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
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ret = -EFAULT;
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if (unlikely(offset >= max_off))
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goto out_unlock;
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}
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ret = -EEXIST;
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if (!pte_none(*dst_pte))
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goto out_unlock;
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set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
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/* No need to invalidate - it was non-present before */
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update_mmu_cache(dst_vma, dst_addr, dst_pte);
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ret = 0;
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out_unlock:
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pte_unmap_unlock(dst_pte, ptl);
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return ret;
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}
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/* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */
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static int mcontinue_atomic_pte(struct mm_struct *dst_mm,
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pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr,
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bool wp_copy)
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{
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struct inode *inode = file_inode(dst_vma->vm_file);
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pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
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struct page *page;
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int ret;
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ret = shmem_getpage(inode, pgoff, &page, SGP_READ);
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if (ret)
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goto out;
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if (!page) {
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ret = -EFAULT;
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goto out;
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}
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if (PageHWPoison(page)) {
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ret = -EIO;
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goto out_release;
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}
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ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
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page, false, wp_copy);
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if (ret)
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goto out_release;
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unlock_page(page);
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ret = 0;
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out:
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return ret;
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out_release:
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unlock_page(page);
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put_page(page);
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goto out;
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}
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static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
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{
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pgd_t *pgd;
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p4d_t *p4d;
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pud_t *pud;
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pgd = pgd_offset(mm, address);
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p4d = p4d_alloc(mm, pgd, address);
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if (!p4d)
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return NULL;
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pud = pud_alloc(mm, p4d, address);
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if (!pud)
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return NULL;
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/*
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* Note that we didn't run this because the pmd was
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* missing, the *pmd may be already established and in
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* turn it may also be a trans_huge_pmd.
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*/
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return pmd_alloc(mm, pud, address);
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}
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#ifdef CONFIG_HUGETLB_PAGE
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/*
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* __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
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* called with mmap_lock held, it will release mmap_lock before returning.
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*/
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static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
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struct vm_area_struct *dst_vma,
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unsigned long dst_start,
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unsigned long src_start,
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unsigned long len,
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enum mcopy_atomic_mode mode,
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bool wp_copy)
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{
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int vm_shared = dst_vma->vm_flags & VM_SHARED;
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ssize_t err;
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pte_t *dst_pte;
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unsigned long src_addr, dst_addr;
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long copied;
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struct page *page;
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unsigned long vma_hpagesize;
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pgoff_t idx;
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u32 hash;
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struct address_space *mapping;
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|
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/*
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* There is no default zero huge page for all huge page sizes as
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* supported by hugetlb. A PMD_SIZE huge pages may exist as used
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* by THP. Since we can not reliably insert a zero page, this
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* feature is not supported.
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*/
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if (mode == MCOPY_ATOMIC_ZEROPAGE) {
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mmap_read_unlock(dst_mm);
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return -EINVAL;
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}
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src_addr = src_start;
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dst_addr = dst_start;
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copied = 0;
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page = NULL;
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vma_hpagesize = vma_kernel_pagesize(dst_vma);
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|
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/*
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* Validate alignment based on huge page size
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*/
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err = -EINVAL;
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if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
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goto out_unlock;
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retry:
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/*
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* On routine entry dst_vma is set. If we had to drop mmap_lock and
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* retry, dst_vma will be set to NULL and we must lookup again.
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*/
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if (!dst_vma) {
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err = -ENOENT;
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dst_vma = find_dst_vma(dst_mm, dst_start, len);
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if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
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goto out_unlock;
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err = -EINVAL;
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if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
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goto out_unlock;
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vm_shared = dst_vma->vm_flags & VM_SHARED;
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}
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/*
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* If not shared, ensure the dst_vma has a anon_vma.
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*/
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err = -ENOMEM;
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if (!vm_shared) {
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if (unlikely(anon_vma_prepare(dst_vma)))
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goto out_unlock;
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}
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while (src_addr < src_start + len) {
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BUG_ON(dst_addr >= dst_start + len);
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/*
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* Serialize via i_mmap_rwsem and hugetlb_fault_mutex.
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* i_mmap_rwsem ensures the dst_pte remains valid even
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* in the case of shared pmds. fault mutex prevents
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* races with other faulting threads.
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*/
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mapping = dst_vma->vm_file->f_mapping;
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i_mmap_lock_read(mapping);
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idx = linear_page_index(dst_vma, dst_addr);
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hash = hugetlb_fault_mutex_hash(mapping, idx);
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mutex_lock(&hugetlb_fault_mutex_table[hash]);
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err = -ENOMEM;
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dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize);
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if (!dst_pte) {
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mutex_unlock(&hugetlb_fault_mutex_table[hash]);
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i_mmap_unlock_read(mapping);
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goto out_unlock;
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}
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|
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if (mode != MCOPY_ATOMIC_CONTINUE &&
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!huge_pte_none_mostly(huge_ptep_get(dst_pte))) {
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err = -EEXIST;
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mutex_unlock(&hugetlb_fault_mutex_table[hash]);
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i_mmap_unlock_read(mapping);
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goto out_unlock;
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}
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|
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err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
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dst_addr, src_addr, mode, &page,
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wp_copy);
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|
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mutex_unlock(&hugetlb_fault_mutex_table[hash]);
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i_mmap_unlock_read(mapping);
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|
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cond_resched();
|
|
|
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if (unlikely(err == -ENOENT)) {
|
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mmap_read_unlock(dst_mm);
|
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BUG_ON(!page);
|
|
|
|
err = copy_huge_page_from_user(page,
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(const void __user *)src_addr,
|
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vma_hpagesize / PAGE_SIZE,
|
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true);
|
|
if (unlikely(err)) {
|
|
err = -EFAULT;
|
|
goto out;
|
|
}
|
|
mmap_read_lock(dst_mm);
|
|
|
|
dst_vma = NULL;
|
|
goto retry;
|
|
} else
|
|
BUG_ON(page);
|
|
|
|
if (!err) {
|
|
dst_addr += vma_hpagesize;
|
|
src_addr += vma_hpagesize;
|
|
copied += vma_hpagesize;
|
|
|
|
if (fatal_signal_pending(current))
|
|
err = -EINTR;
|
|
}
|
|
if (err)
|
|
break;
|
|
}
|
|
|
|
out_unlock:
|
|
mmap_read_unlock(dst_mm);
|
|
out:
|
|
if (page)
|
|
put_page(page);
|
|
BUG_ON(copied < 0);
|
|
BUG_ON(err > 0);
|
|
BUG_ON(!copied && !err);
|
|
return copied ? copied : err;
|
|
}
|
|
#else /* !CONFIG_HUGETLB_PAGE */
|
|
/* fail at build time if gcc attempts to use this */
|
|
extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
|
|
struct vm_area_struct *dst_vma,
|
|
unsigned long dst_start,
|
|
unsigned long src_start,
|
|
unsigned long len,
|
|
enum mcopy_atomic_mode mode,
|
|
bool wp_copy);
|
|
#endif /* CONFIG_HUGETLB_PAGE */
|
|
|
|
static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
|
|
pmd_t *dst_pmd,
|
|
struct vm_area_struct *dst_vma,
|
|
unsigned long dst_addr,
|
|
unsigned long src_addr,
|
|
struct page **page,
|
|
enum mcopy_atomic_mode mode,
|
|
bool wp_copy)
|
|
{
|
|
ssize_t err;
|
|
|
|
if (mode == MCOPY_ATOMIC_CONTINUE) {
|
|
return mcontinue_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
|
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wp_copy);
|
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}
|
|
|
|
/*
|
|
* The normal page fault path for a shmem will invoke the
|
|
* fault, fill the hole in the file and COW it right away. The
|
|
* result generates plain anonymous memory. So when we are
|
|
* asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll
|
|
* generate anonymous memory directly without actually filling
|
|
* the hole. For the MAP_PRIVATE case the robustness check
|
|
* only happens in the pagetable (to verify it's still none)
|
|
* and not in the radix tree.
|
|
*/
|
|
if (!(dst_vma->vm_flags & VM_SHARED)) {
|
|
if (mode == MCOPY_ATOMIC_NORMAL)
|
|
err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
|
|
dst_addr, src_addr, page,
|
|
wp_copy);
|
|
else
|
|
err = mfill_zeropage_pte(dst_mm, dst_pmd,
|
|
dst_vma, dst_addr);
|
|
} else {
|
|
err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
|
|
dst_addr, src_addr,
|
|
mode != MCOPY_ATOMIC_NORMAL,
|
|
wp_copy, page);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
|
|
unsigned long dst_start,
|
|
unsigned long src_start,
|
|
unsigned long len,
|
|
enum mcopy_atomic_mode mcopy_mode,
|
|
atomic_t *mmap_changing,
|
|
__u64 mode)
|
|
{
|
|
struct vm_area_struct *dst_vma;
|
|
ssize_t err;
|
|
pmd_t *dst_pmd;
|
|
unsigned long src_addr, dst_addr;
|
|
long copied;
|
|
struct page *page;
|
|
bool wp_copy;
|
|
|
|
/*
|
|
* Sanitize the command parameters:
|
|
*/
|
|
BUG_ON(dst_start & ~PAGE_MASK);
|
|
BUG_ON(len & ~PAGE_MASK);
|
|
|
|
/* Does the address range wrap, or is the span zero-sized? */
|
|
BUG_ON(src_start + len <= src_start);
|
|
BUG_ON(dst_start + len <= dst_start);
|
|
|
|
src_addr = src_start;
|
|
dst_addr = dst_start;
|
|
copied = 0;
|
|
page = NULL;
|
|
retry:
|
|
mmap_read_lock(dst_mm);
|
|
|
|
/*
|
|
* If memory mappings are changing because of non-cooperative
|
|
* operation (e.g. mremap) running in parallel, bail out and
|
|
* request the user to retry later
|
|
*/
|
|
err = -EAGAIN;
|
|
if (mmap_changing && atomic_read(mmap_changing))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* Make sure the vma is not shared, that the dst range is
|
|
* both valid and fully within a single existing vma.
|
|
*/
|
|
err = -ENOENT;
|
|
dst_vma = find_dst_vma(dst_mm, dst_start, len);
|
|
if (!dst_vma)
|
|
goto out_unlock;
|
|
|
|
err = -EINVAL;
|
|
/*
|
|
* shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but
|
|
* it will overwrite vm_ops, so vma_is_anonymous must return false.
|
|
*/
|
|
if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) &&
|
|
dst_vma->vm_flags & VM_SHARED))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* validate 'mode' now that we know the dst_vma: don't allow
|
|
* a wrprotect copy if the userfaultfd didn't register as WP.
|
|
*/
|
|
wp_copy = mode & UFFDIO_COPY_MODE_WP;
|
|
if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* If this is a HUGETLB vma, pass off to appropriate routine
|
|
*/
|
|
if (is_vm_hugetlb_page(dst_vma))
|
|
return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
|
|
src_start, len, mcopy_mode,
|
|
wp_copy);
|
|
|
|
if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
|
|
goto out_unlock;
|
|
if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE)
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* Ensure the dst_vma has a anon_vma or this page
|
|
* would get a NULL anon_vma when moved in the
|
|
* dst_vma.
|
|
*/
|
|
err = -ENOMEM;
|
|
if (!(dst_vma->vm_flags & VM_SHARED) &&
|
|
unlikely(anon_vma_prepare(dst_vma)))
|
|
goto out_unlock;
|
|
|
|
while (src_addr < src_start + len) {
|
|
pmd_t dst_pmdval;
|
|
|
|
BUG_ON(dst_addr >= dst_start + len);
|
|
|
|
dst_pmd = mm_alloc_pmd(dst_mm, dst_addr);
|
|
if (unlikely(!dst_pmd)) {
|
|
err = -ENOMEM;
|
|
break;
|
|
}
|
|
|
|
dst_pmdval = pmd_read_atomic(dst_pmd);
|
|
/*
|
|
* If the dst_pmd is mapped as THP don't
|
|
* override it and just be strict.
|
|
*/
|
|
if (unlikely(pmd_trans_huge(dst_pmdval))) {
|
|
err = -EEXIST;
|
|
break;
|
|
}
|
|
if (unlikely(pmd_none(dst_pmdval)) &&
|
|
unlikely(__pte_alloc(dst_mm, dst_pmd))) {
|
|
err = -ENOMEM;
|
|
break;
|
|
}
|
|
/* If an huge pmd materialized from under us fail */
|
|
if (unlikely(pmd_trans_huge(*dst_pmd))) {
|
|
err = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
BUG_ON(pmd_none(*dst_pmd));
|
|
BUG_ON(pmd_trans_huge(*dst_pmd));
|
|
|
|
err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
|
|
src_addr, &page, mcopy_mode, wp_copy);
|
|
cond_resched();
|
|
|
|
if (unlikely(err == -ENOENT)) {
|
|
void *page_kaddr;
|
|
|
|
mmap_read_unlock(dst_mm);
|
|
BUG_ON(!page);
|
|
|
|
page_kaddr = kmap(page);
|
|
err = copy_from_user(page_kaddr,
|
|
(const void __user *) src_addr,
|
|
PAGE_SIZE);
|
|
kunmap(page);
|
|
if (unlikely(err)) {
|
|
err = -EFAULT;
|
|
goto out;
|
|
}
|
|
flush_dcache_page(page);
|
|
goto retry;
|
|
} else
|
|
BUG_ON(page);
|
|
|
|
if (!err) {
|
|
dst_addr += PAGE_SIZE;
|
|
src_addr += PAGE_SIZE;
|
|
copied += PAGE_SIZE;
|
|
|
|
if (fatal_signal_pending(current))
|
|
err = -EINTR;
|
|
}
|
|
if (err)
|
|
break;
|
|
}
|
|
|
|
out_unlock:
|
|
mmap_read_unlock(dst_mm);
|
|
out:
|
|
if (page)
|
|
put_page(page);
|
|
BUG_ON(copied < 0);
|
|
BUG_ON(err > 0);
|
|
BUG_ON(!copied && !err);
|
|
return copied ? copied : err;
|
|
}
|
|
|
|
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)
|
|
{
|
|
return __mcopy_atomic(dst_mm, dst_start, src_start, len,
|
|
MCOPY_ATOMIC_NORMAL, mmap_changing, mode);
|
|
}
|
|
|
|
ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
|
|
unsigned long len, atomic_t *mmap_changing)
|
|
{
|
|
return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE,
|
|
mmap_changing, 0);
|
|
}
|
|
|
|
ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long start,
|
|
unsigned long len, atomic_t *mmap_changing)
|
|
{
|
|
return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE,
|
|
mmap_changing, 0);
|
|
}
|
|
|
|
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;
|
|
struct mmu_gather tlb;
|
|
pgprot_t newprot;
|
|
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
|
|
* request the user to retry later
|
|
*/
|
|
err = -EAGAIN;
|
|
if (mmap_changing && atomic_read(mmap_changing))
|
|
goto out_unlock;
|
|
|
|
err = -ENOENT;
|
|
dst_vma = find_dst_vma(dst_mm, start, len);
|
|
|
|
if (!dst_vma)
|
|
goto out_unlock;
|
|
if (!userfaultfd_wp(dst_vma))
|
|
goto out_unlock;
|
|
if (!vma_can_userfault(dst_vma, dst_vma->vm_flags))
|
|
goto out_unlock;
|
|
|
|
if (is_vm_hugetlb_page(dst_vma)) {
|
|
err = -EINVAL;
|
|
page_mask = vma_kernel_pagesize(dst_vma) - 1;
|
|
if ((start & page_mask) || (len & page_mask))
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (enable_wp)
|
|
newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE));
|
|
else
|
|
newprot = vm_get_page_prot(dst_vma->vm_flags);
|
|
|
|
tlb_gather_mmu(&tlb, dst_mm);
|
|
change_protection(&tlb, dst_vma, start, start + len, newprot,
|
|
enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE);
|
|
tlb_finish_mmu(&tlb);
|
|
|
|
err = 0;
|
|
out_unlock:
|
|
mmap_read_unlock(dst_mm);
|
|
return err;
|
|
}
|