diff options
| -rw-r--r-- | include/linux/pagemap.h | 24 |
1 files changed, 9 insertions, 15 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index fe1513ffb7bf..97354102794d 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -518,33 +518,27 @@ void page_endio(struct page *page, int rw, int err); extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter); /* - * Fault a userspace page into pagetables. Return non-zero on a fault. - * - * This assumes that two userspace pages are always sufficient. + * Fault one or two userspace pages into pagetables. + * Return -EINVAL if more than two pages would be needed. + * Return non-zero on a fault. */ static inline int fault_in_pages_writeable(char __user *uaddr, int size) { - int ret; + int span, ret; if (unlikely(size == 0)) return 0; + span = offset_in_page(uaddr) + size; + if (span > 2 * PAGE_SIZE) + return -EINVAL; /* * Writing zeroes into userspace here is OK, because we know that if * the zero gets there, we'll be overwriting it. */ ret = __put_user(0, uaddr); - if (ret == 0) { - char __user *end = uaddr + size - 1; - - /* - * If the page was already mapped, this will get a cache miss - * for sure, so try to avoid doing it. - */ - if (((unsigned long)uaddr & PAGE_MASK) != - ((unsigned long)end & PAGE_MASK)) - ret = __put_user(0, end); - } + if (ret == 0 && span > PAGE_SIZE) + ret = __put_user(0, uaddr + size - 1); return ret; } |