From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
hugetlb_mcopy_atomic_pte is the low level routine that implements
the userfaultfd UFFDIO_COPY command. It is based on the existing
mcopy_atomic_pte routine with modifications for huge pages.
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
include/linux/hugetlb.h | 8 ++++-
mm/hugetlb.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+), 1 deletion(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 48c76d6..fc27b66 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -81,6 +81,11 @@ void hugetlb_show_meminfo(void);
unsigned long hugetlb_total_pages(void);
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags);
+int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr,
+ unsigned long src_addr,
+ struct page **pagep);
int hugetlb_reserve_pages(struct inode *inode, long from, long to,
struct vm_area_struct *vma,
vm_flags_t vm_flags);
@@ -149,6 +154,8 @@ static inline void hugetlb_show_meminfo(void)
#define is_hugepage_only_range(mm, addr, len) 0
#define hugetlb_free_pgd_range(tlb, addr, end, floor, ceiling) ({BUG(); 0; })
#define hugetlb_fault(mm, vma, addr, flags) ({ BUG(); 0; })
+#define hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
+ src_addr, pagep) ({ BUG(); 0; })
#define huge_pte_offset(mm, address) 0
static inline int dequeue_hwpoisoned_huge_page(struct page *page)
{
@@ -272,7 +279,6 @@ static inline bool is_file_hugepages(struct file *file)
return is_file_shm_hugepages(file);
}
-
#else /* !CONFIG_HUGETLBFS */
#define is_file_hugepages(file) false
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ec49d9e..baf7fd4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3857,6 +3857,87 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
return ret;
}
+/*
+ * Used by userfaultfd UFFDIO_COPY. Based on mcopy_atomic_pte with
+ * modifications for huge pages.
+ */
+int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
+ pte_t *dst_pte,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr,
+ unsigned long src_addr,
+ struct page **pagep)
+{
+ struct hstate *h = hstate_vma(dst_vma);
+ pte_t _dst_pte;
+ spinlock_t *ptl;
+ int ret;
+ struct page *page;
+
+ if (!*pagep) {
+ ret = -ENOMEM;
+ page = alloc_huge_page(dst_vma, dst_addr, 0);
+ if (IS_ERR(page))
+ goto out;
+
+ ret = copy_huge_page_from_user(page,
+ (const void __user *) src_addr,
+ pages_per_huge_page(h));
+
+ /* fallback to copy_from_user outside mmap_sem */
+ if (unlikely(ret)) {
+ ret = -EFAULT;
+ *pagep = page;
+ /* don't free the page */
+ goto out;
+ }
+ } else {
+ page = *pagep;
+ *pagep = NULL;
+ }
+
+ /*
+ * The memory barrier inside __SetPageUptodate makes sure that
+ * preceding stores to the page contents become visible before
+ * the set_pte_at() write.
+ */
+ __SetPageUptodate(page);
+ set_page_huge_active(page);
+
+ ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
+ spin_lock(ptl);
+
+ ret = -EEXIST;
+ if (!huge_pte_none(huge_ptep_get(dst_pte)))
+ goto out_release_unlock;
+
+ ClearPagePrivate(page);
+ hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
+
+ _dst_pte = make_huge_pte(dst_vma, page, dst_vma->vm_flags & VM_WRITE);
+ if (dst_vma->vm_flags & VM_WRITE)
+ _dst_pte = huge_pte_mkdirty(_dst_pte);
+ _dst_pte = pte_mkyoung(_dst_pte);
+
+ set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+
+ (void)huge_ptep_set_access_flags(dst_vma, dst_addr, dst_pte, _dst_pte,
+ dst_vma->vm_flags & VM_WRITE);
+ hugetlb_count_add(pages_per_huge_page(h), dst_mm);
+
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(dst_vma, dst_addr, dst_pte);
+
+ spin_unlock(ptl);
+ ret = 0;
+out:
+ return ret;
+out_release_unlock:
+ spin_unlock(ptl);
+ put_page(page);
+ goto out;
+}
+
long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,
unsigned long *position, unsigned long *nr_pages,
--
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