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-rw-r--r--mm/userfaultfd.c793
1 files changed, 793 insertions, 0 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
new file mode 100644
index 000000000..650ab6cfd
--- /dev/null
+++ b/mm/userfaultfd.c
@@ -0,0 +1,793 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mm/userfaultfd.c
+ *
+ * Copyright (C) 2015 Red Hat, Inc.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/pagemap.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/mmu_notifier.h>
+#include <linux/hugetlb.h>
+#include <linux/shmem_fs.h>
+#include <asm/tlbflush.h>
+#include <asm/tlb.h>
+#include "internal.h"
+
+static __always_inline
+struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm,
+ unsigned long dst_start,
+ unsigned long len)
+{
+ /*
+ * Make sure that the dst range is both valid and fully within a
+ * single existing vma.
+ */
+ struct vm_area_struct *dst_vma;
+
+ dst_vma = find_vma(dst_mm, dst_start);
+ if (!dst_vma)
+ return NULL;
+
+ if (dst_start < dst_vma->vm_start ||
+ dst_start + len > dst_vma->vm_end)
+ return NULL;
+
+ /*
+ * Check the vma is registered in uffd, this is required to
+ * enforce the VM_MAYWRITE check done at uffd registration
+ * time.
+ */
+ if (!dst_vma->vm_userfaultfd_ctx.ctx)
+ return NULL;
+
+ return dst_vma;
+}
+
+/*
+ * Install PTEs, to map dst_addr (within dst_vma) to page.
+ *
+ * This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem
+ * and anon, and for both shared and private VMAs.
+ */
+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)
+{
+ int ret;
+ pte_t _dst_pte, *dst_pte;
+ bool writable = dst_vma->vm_flags & VM_WRITE;
+ bool vm_shared = dst_vma->vm_flags & VM_SHARED;
+ bool page_in_cache = page_mapping(page);
+ spinlock_t *ptl;
+ struct inode *inode;
+ pgoff_t offset, max_off;
+
+ _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
+ _dst_pte = pte_mkdirty(_dst_pte);
+ if (page_in_cache && !vm_shared)
+ writable = false;
+
+ /*
+ * Always mark a PTE as write-protected when needed, regardless of
+ * VM_WRITE, which the user might change.
+ */
+ if (wp_copy) {
+ _dst_pte = pte_mkuffd_wp(_dst_pte);
+ writable = false;
+ }
+
+ if (writable)
+ _dst_pte = pte_mkwrite(_dst_pte);
+ else
+ /*
+ * We need this to make sure write bit removed; as mk_pte()
+ * could return a pte with write bit set.
+ */
+ _dst_pte = pte_wrprotect(_dst_pte);
+
+ dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+
+ if (vma_is_shmem(dst_vma)) {
+ /* serialize against truncate with the page table lock */
+ inode = dst_vma->vm_file->f_inode;
+ offset = linear_page_index(dst_vma, dst_addr);
+ max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+ ret = -EFAULT;
+ if (unlikely(offset >= max_off))
+ goto out_unlock;
+ }
+
+ ret = -EEXIST;
+ /*
+ * We allow to overwrite a pte marker: consider when both MISSING|WP
+ * registered, we firstly wr-protect a none pte which has no page cache
+ * page backing it, then access the page.
+ */
+ if (!pte_none_mostly(*dst_pte))
+ goto out_unlock;
+
+ if (page_in_cache) {
+ /* Usually, cache pages are already added to LRU */
+ if (newly_allocated)
+ lru_cache_add(page);
+ page_add_file_rmap(page, dst_vma, false);
+ } else {
+ page_add_new_anon_rmap(page, dst_vma, dst_addr);
+ lru_cache_add_inactive_or_unevictable(page, dst_vma);
+ }
+
+ /*
+ * Must happen after rmap, as mm_counter() checks mapping (via
+ * PageAnon()), which is set by __page_set_anon_rmap().
+ */
+ inc_mm_counter(dst_mm, mm_counter(page));
+
+ set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(dst_vma, dst_addr, dst_pte);
+ ret = 0;
+out_unlock:
+ pte_unmap_unlock(dst_pte, ptl);
+ return ret;
+}
+
+static int mcopy_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 **pagep,
+ bool wp_copy)
+{
+ void *page_kaddr;
+ int ret;
+ struct page *page;
+
+ if (!*pagep) {
+ ret = -ENOMEM;
+ page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);
+ if (!page)
+ goto out;
+
+ page_kaddr = kmap_local_page(page);
+ /*
+ * The read mmap_lock is held here. Despite the
+ * mmap_lock being read recursive a deadlock is still
+ * possible if a writer has taken a lock. For example:
+ *
+ * process A thread 1 takes read lock on own mmap_lock
+ * process A thread 2 calls mmap, blocks taking write lock
+ * process B thread 1 takes page fault, read lock on own mmap lock
+ * process B thread 2 calls mmap, blocks taking write lock
+ * process A thread 1 blocks taking read lock on process B
+ * process B thread 1 blocks taking read lock on process A
+ *
+ * Disable page faults to prevent potential deadlock
+ * and retry the copy outside the mmap_lock.
+ */
+ pagefault_disable();
+ ret = copy_from_user(page_kaddr,
+ (const void __user *) src_addr,
+ PAGE_SIZE);
+ pagefault_enable();
+ kunmap_local(page_kaddr);
+
+ /* fallback to copy_from_user outside mmap_lock */
+ if (unlikely(ret)) {
+ ret = -ENOENT;
+ *pagep = page;
+ /* don't free the page */
+ goto out;
+ }
+
+ flush_dcache_page(page);
+ } else {
+ page = *pagep;
+ *pagep = NULL;
+ }
+
+ /*
+ * The memory barrier inside __SetPageUptodate makes sure that
+ * preceding stores to the page contents become visible before
+ * the set_pte_at() write.
+ */
+ __SetPageUptodate(page);
+
+ ret = -ENOMEM;
+ if (mem_cgroup_charge(page_folio(page), dst_mm, GFP_KERNEL))
+ goto out_release;
+
+ ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
+ page, true, wp_copy);
+ if (ret)
+ goto out_release;
+out:
+ return ret;
+out_release:
+ put_page(page);
+ goto out;
+}
+
+static int mfill_zeropage_pte(struct mm_struct *dst_mm,
+ pmd_t *dst_pmd,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr)
+{
+ pte_t _dst_pte, *dst_pte;
+ spinlock_t *ptl;
+ int ret;
+ pgoff_t offset, max_off;
+ struct inode *inode;
+
+ _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
+ dst_vma->vm_page_prot));
+ dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+ if (dst_vma->vm_file) {
+ /* the shmem MAP_PRIVATE case requires checking the i_size */
+ inode = dst_vma->vm_file->f_inode;
+ offset = linear_page_index(dst_vma, dst_addr);
+ max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+ ret = -EFAULT;
+ if (unlikely(offset >= max_off))
+ goto out_unlock;
+ }
+ ret = -EEXIST;
+ if (!pte_none(*dst_pte))
+ goto out_unlock;
+ set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(dst_vma, dst_addr, dst_pte);
+ ret = 0;
+out_unlock:
+ pte_unmap_unlock(dst_pte, ptl);
+ return ret;
+}
+
+/* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */
+static int mcontinue_atomic_pte(struct mm_struct *dst_mm,
+ pmd_t *dst_pmd,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr,
+ bool wp_copy)
+{
+ struct inode *inode = file_inode(dst_vma->vm_file);
+ pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
+ struct folio *folio;
+ struct page *page;
+ int ret;
+
+ ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC);
+ /* Our caller expects us to return -EFAULT if we failed to find folio */
+ if (ret == -ENOENT)
+ ret = -EFAULT;
+ if (ret)
+ goto out;
+ if (!folio) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ page = folio_file_page(folio, pgoff);
+ if (PageHWPoison(page)) {
+ ret = -EIO;
+ goto out_release;
+ }
+
+ ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
+ page, false, wp_copy);
+ if (ret)
+ goto out_release;
+
+ folio_unlock(folio);
+ ret = 0;
+out:
+ return ret;
+out_release:
+ folio_unlock(folio);
+ folio_put(folio);
+ goto out;
+}
+
+static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
+{
+ pgd_t *pgd;
+ p4d_t *p4d;
+ pud_t *pud;
+
+ pgd = pgd_offset(mm, address);
+ p4d = p4d_alloc(mm, pgd, address);
+ if (!p4d)
+ return NULL;
+ pud = pud_alloc(mm, p4d, address);
+ if (!pud)
+ return NULL;
+ /*
+ * Note that we didn't run this because the pmd was
+ * missing, the *pmd may be already established and in
+ * turn it may also be a trans_huge_pmd.
+ */
+ return pmd_alloc(mm, pud, address);
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
+ * called with mmap_lock held, it will release mmap_lock before returning.
+ */
+static __always_inline 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)
+{
+ int vm_shared = dst_vma->vm_flags & VM_SHARED;
+ ssize_t err;
+ pte_t *dst_pte;
+ unsigned long src_addr, dst_addr;
+ long copied;
+ struct page *page;
+ unsigned long vma_hpagesize;
+ pgoff_t idx;
+ u32 hash;
+ struct address_space *mapping;
+
+ /*
+ * There is no default zero huge page for all huge page sizes as
+ * supported by hugetlb. A PMD_SIZE huge pages may exist as used
+ * by THP. Since we can not reliably insert a zero page, this
+ * feature is not supported.
+ */
+ if (mode == MCOPY_ATOMIC_ZEROPAGE) {
+ mmap_read_unlock(dst_mm);
+ return -EINVAL;
+ }
+
+ src_addr = src_start;
+ dst_addr = dst_start;
+ copied = 0;
+ page = NULL;
+ vma_hpagesize = vma_kernel_pagesize(dst_vma);
+
+ /*
+ * Validate alignment based on huge page size
+ */
+ err = -EINVAL;
+ if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
+ goto out_unlock;
+
+retry:
+ /*
+ * On routine entry dst_vma is set. If we had to drop mmap_lock and
+ * retry, dst_vma will be set to NULL and we must lookup again.
+ */
+ if (!dst_vma) {
+ err = -ENOENT;
+ dst_vma = find_dst_vma(dst_mm, dst_start, len);
+ if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
+ goto out_unlock;
+
+ err = -EINVAL;
+ if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
+ goto out_unlock;
+
+ vm_shared = dst_vma->vm_flags & VM_SHARED;
+ }
+
+ /*
+ * If not shared, ensure the dst_vma has a anon_vma.
+ */
+ err = -ENOMEM;
+ if (!vm_shared) {
+ if (unlikely(anon_vma_prepare(dst_vma)))
+ goto out_unlock;
+ }
+
+ while (src_addr < src_start + len) {
+ BUG_ON(dst_addr >= dst_start + len);
+
+ /*
+ * Serialize via vma_lock and hugetlb_fault_mutex.
+ * vma_lock ensures the dst_pte remains valid even
+ * in the case of shared pmds. fault mutex prevents
+ * races with other faulting threads.
+ */
+ idx = linear_page_index(dst_vma, dst_addr);
+ mapping = dst_vma->vm_file->f_mapping;
+ hash = hugetlb_fault_mutex_hash(mapping, idx);
+ mutex_lock(&hugetlb_fault_mutex_table[hash]);
+ hugetlb_vma_lock_read(dst_vma);
+
+ err = -ENOMEM;
+ dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize);
+ if (!dst_pte) {
+ hugetlb_vma_unlock_read(dst_vma);
+ mutex_unlock(&hugetlb_fault_mutex_table[hash]);
+ goto out_unlock;
+ }
+
+ if (mode != MCOPY_ATOMIC_CONTINUE &&
+ !huge_pte_none_mostly(huge_ptep_get(dst_pte))) {
+ err = -EEXIST;
+ hugetlb_vma_unlock_read(dst_vma);
+ mutex_unlock(&hugetlb_fault_mutex_table[hash]);
+ goto out_unlock;
+ }
+
+ err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
+ dst_addr, src_addr, mode, &page,
+ wp_copy);
+
+ hugetlb_vma_unlock_read(dst_vma);
+ mutex_unlock(&hugetlb_fault_mutex_table[hash]);
+
+ cond_resched();
+
+ if (unlikely(err == -ENOENT)) {
+ mmap_read_unlock(dst_mm);
+ BUG_ON(!page);
+
+ err = copy_huge_page_from_user(page,
+ (const void __user *)src_addr,
+ vma_hpagesize / PAGE_SIZE,
+ 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,
+ wp_copy);
+ }
+
+ /*
+ * 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_local_page(page);
+ err = copy_from_user(page_kaddr,
+ (const void __user *) src_addr,
+ PAGE_SIZE);
+ kunmap_local(page_kaddr);
+ 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);
+}
+
+void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma,
+ unsigned long start, unsigned long len, bool enable_wp)
+{
+ struct mmu_gather tlb;
+ pgprot_t newprot;
+
+ 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);
+}
+
+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
+ * 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;
+ }
+
+ uffd_wp_range(dst_mm, dst_vma, start, len, enable_wp);
+
+ err = 0;
+out_unlock:
+ mmap_read_unlock(dst_mm);
+ return err;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-18 20:20:22 +0000