From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
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.
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
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 a92c8d7..ec18964 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2404,6 +2404,9 @@ 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 e18c57b..00dc2fe 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4093,6 +4093,31 @@ 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
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