@@ -1257,24 +1257,6 @@ static __always_inline int validate_range(struct mm_struct *mm,
return 0;
}
-static inline bool vma_can_userfault(struct vm_area_struct *vma,
- unsigned long vm_flags)
-{
- /* FIXME: add WP support to hugetlbfs and shmem */
- if (vm_flags & VM_UFFD_WP) {
- if (is_vm_hugetlb_page(vma) || vma_is_shmem(vma))
- return false;
- }
-
- if (vm_flags & VM_UFFD_MINOR) {
- if (!(is_vm_hugetlb_page(vma) || vma_is_shmem(vma)))
- return false;
- }
-
- return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
- vma_is_shmem(vma);
-}
-
static int userfaultfd_register(struct userfaultfd_ctx *ctx,
unsigned long arg)
{
@@ -1955,6 +1937,9 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
#endif
#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP
uffdio_api.features &= ~UFFD_FEATURE_PAGEFAULT_FLAG_WP;
+#endif
+#ifndef CONFIG_PTE_MARKER_UFFD_WP
+ uffdio_api.features &= ~UFFD_FEATURE_WP_HUGETLBFS_SHMEM;
#endif
uffdio_api.ioctls = UFFD_API_IOCTLS;
ret = -EFAULT;
@@ -18,6 +18,7 @@
#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)
@@ -140,6 +141,25 @@ 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)
+{
+ if (vm_flags & VM_UFFD_MINOR)
+ return is_vm_hugetlb_page(vma) || vma_is_shmem(vma);
+
+#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
+ 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 *);
@@ -33,7 +33,8 @@
UFFD_FEATURE_THREAD_ID | \
UFFD_FEATURE_MINOR_HUGETLBFS | \
UFFD_FEATURE_MINOR_SHMEM | \
- UFFD_FEATURE_EXACT_ADDRESS)
+ UFFD_FEATURE_EXACT_ADDRESS | \
+ UFFD_FEATURE_WP_HUGETLBFS_SHMEM)
#define UFFD_API_IOCTLS \
((__u64)1 << _UFFDIO_REGISTER | \
(__u64)1 << _UFFDIO_UNREGISTER | \
@@ -47,7 +48,8 @@
#define UFFD_API_RANGE_IOCTLS_BASIC \
((__u64)1 << _UFFDIO_WAKE | \
(__u64)1 << _UFFDIO_COPY | \
- (__u64)1 << _UFFDIO_CONTINUE)
+ (__u64)1 << _UFFDIO_CONTINUE | \
+ (__u64)1 << _UFFDIO_WRITEPROTECT)
/*
* Valid ioctl command number range with this API is from 0x00 to
@@ -194,6 +196,9 @@ struct uffdio_api {
* UFFD_FEATURE_EXACT_ADDRESS indicates that the exact address of page
* faults would be provided and the offset within the page would not be
* masked.
+ *
+ * UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd
+ * write-protection mode is supported on both shmem and hugetlbfs.
*/
#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
#define UFFD_FEATURE_EVENT_FORK (1<<1)
@@ -207,6 +212,7 @@ struct uffdio_api {
#define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9)
#define UFFD_FEATURE_MINOR_SHMEM (1<<10)
#define UFFD_FEATURE_EXACT_ADDRESS (1<<11)
+#define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1<<12)
__u64 features;
__u64 ioctls;
@@ -730,15 +730,12 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
err = -ENOENT;
dst_vma = find_dst_vma(dst_mm, start, len);
- /*
- * Make sure the vma is not shared, that the dst range is
- * both valid and fully within a single existing vma.
- */
- if (!dst_vma || (dst_vma->vm_flags & VM_SHARED))
+
+ if (!dst_vma)
goto out_unlock;
if (!userfaultfd_wp(dst_vma))
goto out_unlock;
- if (!vma_is_anonymous(dst_vma))
+ if (!vma_can_userfault(dst_vma, dst_vma->vm_flags))
goto out_unlock;
if (is_vm_hugetlb_page(dst_vma)) {
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. Signed-off-by: Peter Xu <peterx@redhat.com> --- fs/userfaultfd.c | 21 +++------------------ include/linux/userfaultfd_k.h | 20 ++++++++++++++++++++ include/uapi/linux/userfaultfd.h | 10 ++++++++-- mm/userfaultfd.c | 9 +++------ 4 files changed, 34 insertions(+), 26 deletions(-)