1 files changed, 81 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 9b68a72f8c17..96f1d473c89a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1527,6 +1527,87 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(vm_insert_page);
 
+/*
+ * __vm_map_pages - maps range of kernel pages into user vma
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ * @offset: user's requested vm_pgoff
+ *
+ * This allows drivers to map range of kernel pages into a user vma.
+ *
+ * Return: 0 on success and error code otherwise.
+ */
+static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
+                                unsigned long num, unsigned long offset)
+{
+        unsigned long count = vma_pages(vma);
+        unsigned long uaddr = vma->vm_start;
+        int ret, i;
+
+        /* Fail if the user requested offset is beyond the end of the object */
+        if (offset > num)
+                return -ENXIO;
+
+        /* Fail if the user requested size exceeds available object size */
+        if (count > num - offset)
+                return -ENXIO;
+
+        for (i = 0; i < count; i++) {
+                ret = vm_insert_page(vma, uaddr, pages[offset + i]);
+                if (ret < 0)
+                        return ret;
+                uaddr += PAGE_SIZE;
+        }
+
+        return 0;
+}
+
+/**
+ * vm_map_pages - maps range of kernel pages starts with non zero offset
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ *
+ * Maps an object consisting of @num pages, catering for the user's
+ * requested vm_pgoff
+ *
+ * If we fail to insert any page into the vma, the function will return
+ * immediately leaving any previously inserted pages present.  Callers
+ * from the mmap handler may immediately return the error as their caller
+ * will destroy the vma, removing any successfully inserted pages. Other
+ * callers should make their own arrangements for calling unmap_region().
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise.
+ */
+int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
+                                unsigned long num)
+{
+        return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
+}
+EXPORT_SYMBOL(vm_map_pages);
+
+/**
+ * vm_map_pages_zero - map range of kernel pages starts with zero offset
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ *
+ * Similar to vm_map_pages(), except that it explicitly sets the offset
+ * to 0. This function is intended for the drivers that did not consider
+ * vm_pgoff.
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise.
+ */
+int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
+                                unsigned long num)
+{
+        return __vm_map_pages(vma, pages, num, 0);
+}
+EXPORT_SYMBOL(vm_map_pages_zero);
+
 static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
                         pfn_t pfn, pgprot_t prot, bool mkwrite)
 {