From 62c95d19b2a30ef911b9679451a9447406ca4b15 Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Thu, 12 Jan 2017 12:19:14 +1100 Subject: [PATCH] userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support Orabug: 21685254 userfaultfd UFFDIO_COPY allows user level code to copy data to a page at fault time. The data is copied from user space to a newly allocated huge page. The new routine copy_huge_page_from_user performs this copy. Link: http://lkml.kernel.org/r/20161216144821.5183-17-aarcange@redhat.com Signed-off-by: Mike Kravetz Signed-off-by: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Hillf Danton Cc: Michael Rapoport Cc: Mike Kravetz Cc: Pavel Emelyanov Signed-off-by: Andrew Morton (cherry picked from linux-next next-20170117 commit 33424a2bf04a630438a7bb8d53a2477ba7527164) Signed-off-by: Mike Kravetz Reviewed-by: Dhaval Giani Signed-off-by: Dhaval Giani --- include/linux/mm.h | 3 +++ mm/memory.c | 25 +++++++++++++++++++++++++ 2 files changed, 28 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 916c1cc4334e..288395e54996 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2162,6 +2162,9 @@ extern void clear_huge_page(struct page *page, extern void copy_user_huge_page(struct page *dst, struct page *src, unsigned long addr, struct vm_area_struct *vma, unsigned int pages_per_huge_page); +extern long copy_huge_page_from_user(struct page *dst_page, + const void __user *usr_src, + unsigned int pages_per_huge_page); #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ extern struct page_ext_operations debug_guardpage_ops; diff --git a/mm/memory.c b/mm/memory.c index e70ba44ddd94..739a6a812693 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3849,6 +3849,31 @@ void copy_user_huge_page(struct page *dst, struct page *src, copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); } } + +long copy_huge_page_from_user(struct page *dst_page, + const void __user *usr_src, + unsigned int pages_per_huge_page) +{ + void *src = (void *)usr_src; + void *page_kaddr; + unsigned long i, rc = 0; + unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; + + for (i = 0; i < pages_per_huge_page; i++) { + page_kaddr = kmap_atomic(dst_page + i); + rc = copy_from_user(page_kaddr, + (const void __user *)(src + i * PAGE_SIZE), + PAGE_SIZE); + kunmap_atomic(page_kaddr); + + ret_val -= (PAGE_SIZE - rc); + if (rc) + break; + + cond_resched(); + } + return ret_val; +} #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS -- 2.50.1