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Diffstat (limited to 'mm/userfaultfd.c')
-rw-r--r--mm/userfaultfd.c172
1 files changed, 127 insertions, 45 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 57b228b9b6a4..218ec2af615f 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -48,6 +48,83 @@ struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm,
return dst_vma;
}
+/*
+ * Install PTEs, to map dst_addr (within dst_vma) to page.
+ *
+ * This function handles MCOPY_ATOMIC_CONTINUE (which is always file-backed),
+ * whether or not dst_vma is VM_SHARED. It also handles the more general
+ * MCOPY_ATOMIC_NORMAL case, when dst_vma is *not* VM_SHARED (it may be file
+ * backed, or not).
+ *
+ * Note that MCOPY_ATOMIC_NORMAL for a VM_SHARED dst_vma is handled by
+ * shmem_mcopy_atomic_pte instead.
+ */
+static 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;
+ spinlock_t *ptl;
+ struct inode *inode;
+ pgoff_t offset, max_off;
+
+ _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
+ if (page_in_cache && !vm_shared)
+ writable = false;
+ if (writable || !page_in_cache)
+ _dst_pte = pte_mkdirty(_dst_pte);
+ if (writable) {
+ if (wp_copy)
+ _dst_pte = pte_mkuffd_wp(_dst_pte);
+ else
+ _dst_pte = pte_mkwrite(_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;
+ if (!pte_none(*dst_pte))
+ goto out_unlock;
+
+ if (page_in_cache)
+ page_add_file_rmap(page, false);
+ else
+ page_add_new_anon_rmap(page, dst_vma, dst_addr, false);
+
+ /*
+ * 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));
+
+ if (newly_allocated)
+ lru_cache_add_inactive_or_unevictable(page, dst_vma);
+
+ 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,
@@ -56,13 +133,9 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
struct page **pagep,
bool wp_copy)
{
- pte_t _dst_pte, *dst_pte;
- spinlock_t *ptl;
void *page_kaddr;
int ret;
struct page *page;
- pgoff_t offset, max_off;
- struct inode *inode;
if (!*pagep) {
ret = -ENOMEM;
@@ -99,43 +172,12 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
if (mem_cgroup_charge(page, dst_mm, GFP_KERNEL))
goto out_release;
- _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot));
- if (dst_vma->vm_flags & VM_WRITE) {
- if (wp_copy)
- _dst_pte = pte_mkuffd_wp(_dst_pte);
- else
- _dst_pte = pte_mkwrite(_dst_pte);
- }
-
- 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_release_uncharge_unlock;
- }
- ret = -EEXIST;
- if (!pte_none(*dst_pte))
- goto out_release_uncharge_unlock;
-
- inc_mm_counter(dst_mm, MM_ANONPAGES);
- page_add_new_anon_rmap(page, dst_vma, dst_addr, false);
- lru_cache_add_inactive_or_unevictable(page, dst_vma);
-
- 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);
-
- pte_unmap_unlock(dst_pte, ptl);
- ret = 0;
+ 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_uncharge_unlock:
- pte_unmap_unlock(dst_pte, ptl);
out_release:
put_page(page);
goto out;
@@ -176,6 +218,41 @@ out_unlock:
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 page *page;
+ int ret;
+
+ ret = shmem_getpage(inode, pgoff, &page, SGP_READ);
+ if (ret)
+ goto out;
+ if (!page) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
+ page, false, wp_copy);
+ if (ret)
+ goto out_release;
+
+ unlock_page(page);
+ ret = 0;
+out:
+ return ret;
+out_release:
+ unlock_page(page);
+ put_page(page);
+ goto out;
+}
+
static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
{
pgd_t *pgd;
@@ -367,11 +444,16 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
unsigned long dst_addr,
unsigned long src_addr,
struct page **page,
- bool zeropage,
+ 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
@@ -383,7 +465,7 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
* and not in the radix tree.
*/
if (!(dst_vma->vm_flags & VM_SHARED)) {
- if (!zeropage)
+ if (mode == MCOPY_ATOMIC_NORMAL)
err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
dst_addr, src_addr, page,
wp_copy);
@@ -393,7 +475,8 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
} else {
VM_WARN_ON_ONCE(wp_copy);
err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
- dst_addr, src_addr, zeropage,
+ dst_addr, src_addr,
+ mode != MCOPY_ATOMIC_NORMAL,
page);
}
@@ -415,7 +498,6 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
long copied;
struct page *page;
bool wp_copy;
- bool zeropage = (mcopy_mode == MCOPY_ATOMIC_ZEROPAGE);
/*
* Sanitize the command parameters:
@@ -478,7 +560,7 @@ retry:
if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
goto out_unlock;
- if (mcopy_mode == MCOPY_ATOMIC_CONTINUE)
+ if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE)
goto out_unlock;
/*
@@ -526,7 +608,7 @@ retry:
BUG_ON(pmd_trans_huge(*dst_pmd));
err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
- src_addr, &page, zeropage, wp_copy);
+ src_addr, &page, mcopy_mode, wp_copy);
cond_resched();
if (unlikely(err == -ENOENT)) {
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-21 14:53:41 +0000