From: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Subject: userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support 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@xxxxxxxxxx Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm.h | 3 +++ mm/memory.c | 25 +++++++++++++++++++++++++ 2 files changed, 28 insertions(+) diff -puN include/linux/mm.h~userfaultfd-hugetlbfs-add-copy_huge_page_from_user-for-hugetlb-userfaultfd-support include/linux/mm.h --- a/include/linux/mm.h~userfaultfd-hugetlbfs-add-copy_huge_page_from_user-for-hugetlb-userfaultfd-support +++ a/include/linux/mm.h @@ -2424,6 +2424,9 @@ extern void clear_huge_page(struct 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 -puN mm/memory.c~userfaultfd-hugetlbfs-add-copy_huge_page_from_user-for-hugetlb-userfaultfd-support mm/memory.c --- a/mm/memory.c~userfaultfd-hugetlbfs-add-copy_huge_page_from_user-for-hugetlb-userfaultfd-support +++ a/mm/memory.c @@ -4152,6 +4152,31 @@ void copy_user_huge_page(struct page *ds 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 _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
