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Commit fa4d75c1 authored by Mike Kravetz's avatar Mike Kravetz Committed by Linus Torvalds
Browse files

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@redhat.com


Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 09fa5296

include/linux/mm.h

+3 −0
Original line number Diff line number Diff line
@@ -2424,6 +2424,9 @@ 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;

mm/memory.c

+25 −0
Original line number Diff line number Diff line
@@ -4152,6 +4152,31 @@ 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