Commit c40069cb7bd6 ("drm: add mmap() to drm_gem_object_funcs")
introduced a GEM object mmap() hook which is expected to subtract the
fake offset from vm_pgoff. However, for mmap() on dmabufs, there is not
a fake offset.
To fix this, let's always call mmap() object callback with an offset of 0,
and leave it up to drm_gem_mmap_obj() to remove the fake offset.
TTM still needs the fake offset, so we have to add it back until that's
fixed.
Fixes: c40069cb7bd6 ("drm: add mmap() to drm_gem_object_funcs")
Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
v2:
- Move subtracting the fake offset out of mmap() obj callbacks.
I've tested shmem, but not ttm. Hopefully, I understood what's needed
for TTM.
Rob
drivers/gpu/drm/drm_gem.c | 3 +++
drivers/gpu/drm/drm_gem_shmem_helper.c | 3 ---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 7 +++++++
include/drm/drm_gem.h | 4 +++-
4 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 56f42e0f2584..2f2b889096b0 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1106,6 +1106,9 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
return -EINVAL;
if (obj->funcs && obj->funcs->mmap) {
+ /* Remove the fake offset */
+ vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
+
ret = obj->funcs->mmap(obj, vma);
if (ret)
return ret;
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index a878c787b867..e8061c64c480 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -542,9 +542,6 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
vma->vm_ops = &drm_gem_shmem_vm_ops;
- /* Remove the fake offset */
- vma->vm_pgoff -= drm_vma_node_start(&shmem->base.vma_node);
-
return 0;
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 1a9db691f954..08902c7290a5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -482,6 +482,13 @@ EXPORT_SYMBOL(ttm_bo_mmap);
int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
{
ttm_bo_get(bo);
+
+ /*
+ * FIXME: &drm_gem_object_funcs.mmap is called with the fake offset
+ * removed. Add it back here until the rest of TTM works without it.
+ */
+ vma->vm_pgoff += drm_vma_node_start(&bo->base.vma_node);
+
ttm_bo_mmap_vma_setup(bo, vma);
return 0;
}
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index e71f75a2ab57..c56cbb3509e0 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -159,7 +159,9 @@ struct drm_gem_object_funcs {
*
* The callback is used by by both drm_gem_mmap_obj() and
* drm_gem_prime_mmap(). When @mmap is present @vm_ops is not
- * used, the @mmap callback must set vma->vm_ops instead.
+ * used, the @mmap callback must set vma->vm_ops instead. The @mmap
+ * callback is always called with a 0 offset. The caller will remove
+ * the fake offset as necessary.
*
*/
int (*mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);
--
2.20.1
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