diff options
| -rw-r--r-- | Documentation/admin-guide/mm/userfaultfd.rst | 8 | ||||
| -rw-r--r-- | fs/userfaultfd.c | 8 | ||||
| -rw-r--r-- | include/linux/userfaultfd_k.h | 3 | ||||
| -rw-r--r-- | include/uapi/linux/userfaultfd.h | 7 | ||||
| -rw-r--r-- | mm/userfaultfd.c | 5 | ||||
| -rw-r--r-- | tools/testing/selftests/mm/userfaultfd.c | 4 |
6 files changed, 30 insertions, 5 deletions
diff --git a/Documentation/admin-guide/mm/userfaultfd.rst b/Documentation/admin-guide/mm/userfaultfd.rst index bd2226299583..7c304e432205 100644 --- a/Documentation/admin-guide/mm/userfaultfd.rst +++ b/Documentation/admin-guide/mm/userfaultfd.rst @@ -236,6 +236,14 @@ newer kernels, one can also detect the feature UFFD_FEATURE_WP_UNPOPULATED and set the feature bit in advance to make sure none ptes will also be write protected even upon anonymous memory. +When using ``UFFDIO_REGISTER_MODE_WP`` in combination with either +``UFFDIO_REGISTER_MODE_MISSING`` or ``UFFDIO_REGISTER_MODE_MINOR``, when +resolving missing / minor faults with ``UFFDIO_COPY`` or ``UFFDIO_CONTINUE`` +respectively, it may be desirable for the new page / mapping to be +write-protected (so future writes will also result in a WP fault). These ioctls +support a mode flag (``UFFDIO_COPY_MODE_WP`` or ``UFFDIO_CONTINUE_MODE_WP`` +respectively) to configure the mapping this way. + QEMU/KVM ======== diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 8971c3613cc6..8395605790f6 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1893,6 +1893,7 @@ static int userfaultfd_continue(struct userfaultfd_ctx *ctx, unsigned long arg) struct uffdio_continue uffdio_continue; struct uffdio_continue __user *user_uffdio_continue; struct userfaultfd_wake_range range; + uffd_flags_t flags = 0; user_uffdio_continue = (struct uffdio_continue __user *)arg; @@ -1917,13 +1918,16 @@ static int userfaultfd_continue(struct userfaultfd_ctx *ctx, unsigned long arg) uffdio_continue.range.start) { goto out; } - if (uffdio_continue.mode & ~UFFDIO_CONTINUE_MODE_DONTWAKE) + if (uffdio_continue.mode & ~(UFFDIO_CONTINUE_MODE_DONTWAKE | + UFFDIO_CONTINUE_MODE_WP)) goto out; + if (uffdio_continue.mode & UFFDIO_CONTINUE_MODE_WP) + flags |= MFILL_ATOMIC_WP; if (mmget_not_zero(ctx->mm)) { ret = mfill_atomic_continue(ctx->mm, uffdio_continue.range.start, uffdio_continue.range.len, - &ctx->mmap_changing); + &ctx->mmap_changing, flags); mmput(ctx->mm); } else { return -ESRCH; diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 4c477dece540..a2c53e98dfd6 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -83,7 +83,8 @@ extern ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long len, atomic_t *mmap_changing); extern ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long dst_start, - unsigned long len, atomic_t *mmap_changing); + unsigned long len, atomic_t *mmap_changing, + uffd_flags_t flags); extern int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, unsigned long len, bool enable_wp, atomic_t *mmap_changing); diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index 90c958952bfc..66dd4cd277bd 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -305,6 +305,13 @@ struct uffdio_writeprotect { struct uffdio_continue { struct uffdio_range range; #define UFFDIO_CONTINUE_MODE_DONTWAKE ((__u64)1<<0) + /* + * UFFDIO_CONTINUE_MODE_WP will map the page write protected on + * the fly. UFFDIO_CONTINUE_MODE_WP is available only if the + * write protected ioctl is implemented for the range + * according to the uffdio_register.ioctls. + */ +#define UFFDIO_CONTINUE_MODE_WP ((__u64)1<<1) __u64 mode; /* diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index a9b19b39413d..7f1b5f8b712c 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -693,10 +693,11 @@ ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start, } ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start, - unsigned long len, atomic_t *mmap_changing) + unsigned long len, atomic_t *mmap_changing, + uffd_flags_t flags) { return mfill_atomic(dst_mm, start, 0, len, mmap_changing, - uffd_flags_set_mode(0, MFILL_ATOMIC_CONTINUE)); + uffd_flags_set_mode(flags, MFILL_ATOMIC_CONTINUE)); } long uffd_wp_range(struct vm_area_struct *dst_vma, diff --git a/tools/testing/selftests/mm/userfaultfd.c b/tools/testing/selftests/mm/userfaultfd.c index e030d63c031a..a96d126cb40e 100644 --- a/tools/testing/selftests/mm/userfaultfd.c +++ b/tools/testing/selftests/mm/userfaultfd.c @@ -585,6 +585,8 @@ static void continue_range(int ufd, __u64 start, __u64 len) req.range.start = start; req.range.len = len; req.mode = 0; + if (test_uffdio_wp) + req.mode |= UFFDIO_CONTINUE_MODE_WP; if (ioctl(ufd, UFFDIO_CONTINUE, &req)) err("UFFDIO_CONTINUE failed for address 0x%" PRIx64, @@ -1332,6 +1334,8 @@ static int userfaultfd_minor_test(void) uffdio_register.range.start = (unsigned long)area_dst_alias; uffdio_register.range.len = nr_pages * page_size; uffdio_register.mode = UFFDIO_REGISTER_MODE_MINOR; + if (test_uffdio_wp) + uffdio_register.mode |= UFFDIO_REGISTER_MODE_WP; if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) err("register failure"); |