1 files changed, 98 insertions, 1 deletions

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 05c64c11bad2..24e88fe29ec1 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -44,8 +44,26 @@ static int dma_buf_release(struct inode *inode, struct file *file)
         return 0;
 }
 
+static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
+{
+        struct dma_buf *dmabuf;
+
+        if (!is_dma_buf_file(file))
+                return -EINVAL;
+
+        dmabuf = file->private_data;
+
+        /* check for overflowing the buffer's size */
+        if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
+            dmabuf->size >> PAGE_SHIFT)
+                return -EINVAL;
+
+        return dmabuf->ops->mmap(dmabuf, vma);
+}
+
 static const struct file_operations dma_buf_fops = {
         .release        = dma_buf_release,
+        .mmap           = dma_buf_mmap_internal,
 };
 
 /*
@@ -82,7 +100,8 @@ struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
                           || !ops->unmap_dma_buf
                           || !ops->release
                           || !ops->kmap_atomic
-                          || !ops->kmap)) {
+                          || !ops->kmap
+                          || !ops->mmap)) {
                 return ERR_PTR(-EINVAL);
         }
 
@@ -406,3 +425,81 @@ void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
                 dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
 }
 EXPORT_SYMBOL_GPL(dma_buf_kunmap);
+
+
+/**
+ * dma_buf_mmap - Setup up a userspace mmap with the given vma
+ * @dmabuf:     [in]    buffer that should back the vma
+ * @vma:        [in]    vma for the mmap
+ * @pgoff:      [in]    offset in pages where this mmap should start within the
+ *                      dma-buf buffer.
+ *
+ * This function adjusts the passed in vma so that it points at the file of the
+ * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
+ * checking on the size of the vma. Then it calls the exporters mmap function to
+ * set up the mapping.
+ *
+ * Can return negative error values, returns 0 on success.
+ */
+int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
+                 unsigned long pgoff)
+{
+        if (WARN_ON(!dmabuf || !vma))
+                return -EINVAL;
+
+        /* check for offset overflow */
+        if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
+                return -EOVERFLOW;
+
+        /* check for overflowing the buffer's size */
+        if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
+            dmabuf->size >> PAGE_SHIFT)
+                return -EINVAL;
+
+        /* readjust the vma */
+        if (vma->vm_file)
+                fput(vma->vm_file);
+
+        vma->vm_file = dmabuf->file;
+        get_file(vma->vm_file);
+
+        vma->vm_pgoff = pgoff;
+
+        return dmabuf->ops->mmap(dmabuf, vma);
+}
+EXPORT_SYMBOL_GPL(dma_buf_mmap);
+
+/**
+ * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
+ * address space. Same restrictions as for vmap and friends apply.
+ * @dmabuf:     [in]    buffer to vmap
+ *
+ * This call may fail due to lack of virtual mapping address space.
+ * These calls are optional in drivers. The intended use for them
+ * is for mapping objects linear in kernel space for high use objects.
+ * Please attempt to use kmap/kunmap before thinking about these interfaces.
+ */
+void *dma_buf_vmap(struct dma_buf *dmabuf)
+{
+        if (WARN_ON(!dmabuf))
+                return NULL;
+
+        if (dmabuf->ops->vmap)
+                return dmabuf->ops->vmap(dmabuf);
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(dma_buf_vmap);
+
+/**
+ * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
+ * @dmabuf:     [in]    buffer to vunmap
+ */
+void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
+{
+        if (WARN_ON(!dmabuf))
+                return;
+
+        if (dmabuf->ops->vunmap)
+                dmabuf->ops->vunmap(dmabuf, vaddr);
+}
+EXPORT_SYMBOL_GPL(dma_buf_vunmap);