drm/gem: add shmem get/put page helpers

Basically just extracting some code duplicated in gma500, omapdrm, udl,
and upcoming msm driver.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index a8ba7da83d45819ccf45dbe5a0170cdc79c9eecf..a4c8e8fba5997883d391211219d3c38eb1e0095f 100644 (file)
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -358,6 +358,109 @@ int drm_gem_create_mmap_offset(struct drm_gem_object *obj)
 }
 EXPORT_SYMBOL(drm_gem_create_mmap_offset);
 
+/**
+ * drm_gem_get_pages - helper to allocate backing pages for a GEM object
+ * from shmem
+ * @obj: obj in question
+ * @gfpmask: gfp mask of requested pages
+ */
+struct page **drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask)
+{
+       struct inode *inode;
+       struct address_space *mapping;
+       struct page *p, **pages;
+       int i, npages;
+
+       /* This is the shared memory object that backs the GEM resource */
+       inode = file_inode(obj->filp);
+       mapping = inode->i_mapping;
+
+       /* We already BUG_ON() for non-page-aligned sizes in
+        * drm_gem_object_init(), so we should never hit this unless
+        * driver author is doing something really wrong:
+        */
+       WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
+
+       npages = obj->size >> PAGE_SHIFT;
+
+       pages = drm_malloc_ab(npages, sizeof(struct page *));
+       if (pages == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       gfpmask |= mapping_gfp_mask(mapping);
+
+       for (i = 0; i < npages; i++) {
+               p = shmem_read_mapping_page_gfp(mapping, i, gfpmask);
+               if (IS_ERR(p))
+                       goto fail;
+               pages[i] = p;
+
+               /* There is a hypothetical issue w/ drivers that require
+                * buffer memory in the low 4GB.. if the pages are un-
+                * pinned, and swapped out, they can end up swapped back
+                * in above 4GB.  If pages are already in memory, then
+                * shmem_read_mapping_page_gfp will ignore the gfpmask,
+                * even if the already in-memory page disobeys the mask.
+                *
+                * It is only a theoretical issue today, because none of
+                * the devices with this limitation can be populated with
+                * enough memory to trigger the issue.  But this BUG_ON()
+                * is here as a reminder in case the problem with
+                * shmem_read_mapping_page_gfp() isn't solved by the time
+                * it does become a real issue.
+                *
+                * See this thread: http://lkml.org/lkml/2011/7/11/238
+                */
+               BUG_ON((gfpmask & __GFP_DMA32) &&
+                               (page_to_pfn(p) >= 0x00100000UL));
+       }
+
+       return pages;
+
+fail:
+       while (i--)
+               page_cache_release(pages[i]);
+
+       drm_free_large(pages);
+       return ERR_CAST(p);
+}
+EXPORT_SYMBOL(drm_gem_get_pages);
+
+/**
+ * drm_gem_put_pages - helper to free backing pages for a GEM object
+ * @obj: obj in question
+ * @pages: pages to free
+ * @dirty: if true, pages will be marked as dirty
+ * @accessed: if true, the pages will be marked as accessed
+ */
+void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
+               bool dirty, bool accessed)
+{
+       int i, npages;
+
+       /* We already BUG_ON() for non-page-aligned sizes in
+        * drm_gem_object_init(), so we should never hit this unless
+        * driver author is doing something really wrong:
+        */
+       WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
+
+       npages = obj->size >> PAGE_SHIFT;
+
+       for (i = 0; i < npages; i++) {
+               if (dirty)
+                       set_page_dirty(pages[i]);
+
+               if (accessed)
+                       mark_page_accessed(pages[i]);
+
+               /* Undo the reference we took when populating the table */
+               page_cache_release(pages[i]);
+       }
+
+       drm_free_large(pages);
+}
+EXPORT_SYMBOL(drm_gem_put_pages);
+
 /** Returns a reference to the object named by the handle. */
 struct drm_gem_object *
 drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index d6d9a28fc6b4226e4ba83c6a739c737764ac27ef..91f343c8b1606e5eb4b718e7a9f16cd475beac29 100644 (file)
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1616,6 +1616,10 @@ void drm_gem_free_mmap_offset(struct drm_gem_object *obj);
 int drm_gem_create_mmap_offset(struct drm_gem_object *obj);
 int drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size);
 
+struct page **drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask);
+void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
+               bool dirty, bool accessed);
+
 struct drm_gem_object *drm_gem_object_lookup(struct drm_device *dev,
                                             struct drm_file *filp,
                                             u32 handle);