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userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support

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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 <mike.kravetz@oracle.com>
Signed-off-by: Andrea 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2017-02-22 15:42:49 -08:00 committed by Linus Torvalds
parent 09fa5296a4
commit fa4d75c1de
2 changed files with 28 additions and 0 deletions
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3
include/linux/mm.h
View file

@ -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;

25
mm/memory.c
View file

@ -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