drm/bochs: fix bochs_gem_prime_mmap

kraxel · kraxel · commit 86c5b359d9e1 · 2019-02-05T10:28:15.000+01:00
ttm_fbdev_mmap() just doesn't work. It appears to work fine, mmap() returns success, but any attempt to actually access the mapping causes a SIGBUS. We can just use drm_gem_prime_mmap() instead. Almost. We have to copy over the start offset from the ttm_buffer_object vm_node to the drm_gem_object vm_node so the offset math in drm_gem_prime_mmap() works correctly for us even though we use ttm to manage our objects. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20190204183858.8976-1-kraxel@redhat.com
diff --git a/drivers/gpu/drm/bochs/bochs_mm.c b/drivers/gpu/drm/bochs/bochs_mm.c
@@ -442,5 +442,6 @@ int bochs_gem_prime_mmap(struct drm_gem_object *obj,
 {
 	struct bochs_bo *bo = gem_to_bochs_bo(obj);
 
-	return ttm_fbdev_mmap(vma, &bo->bo);
+	bo->gem.vma_node.vm_node.start = bo->bo.vma_node.vm_node.start;
+	return drm_gem_prime_mmap(obj, vma);
 }

Original file line number	Diff line number	Diff line change
`@@ -442,5 +442,6 @@ int bochs_gem_prime_mmap(struct drm_gem_object *obj,`
`442`	`442`	`{`
`443`	`443`	`struct bochs_bo *bo = gem_to_bochs_bo(obj);`
`444`	`444`
`445`		`- return ttm_fbdev_mmap(vma, &bo->bo);`
	`445`	`+ bo->gem.vma_node.vm_node.start = bo->bo.vma_node.vm_node.start;`
	`446`	`+ return drm_gem_prime_mmap(obj, vma);`
`446`	`447`	`}`