drm/gem: Warn on illegal use of the dumb buffer interface v2
It happens on occasion that developers of generic user-space applications
abuse the dumb buffer API to get hold of drm buffers that they can both
mmap() and use for GPU acceleration, using the assumptions that dumb buffers
and buffers available for GPU are
a) The same type and can be aribtrarily type-casted.
b) fully coherent.
This patch makes the most widely used drivers warn nicely when that happens,
the next step will be to fail.
v2: Move drmP.h changes to drm_gem.h. Fix Radeon dumb mmap breakage.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 2404b2b..c743908 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1593,7 +1593,7 @@
.gem_prime_import = i915_gem_prime_import,
.dumb_create = i915_gem_dumb_create,
- .dumb_map_offset = i915_gem_mmap_gtt,
+ .dumb_map_offset = i915_gem_dumb_map_offset,
.dumb_destroy = drm_gem_dumb_destroy,
.ioctls = i915_ioctls,
.fops = &i915_driver_fops,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index f830596..4ba1aca 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2523,8 +2523,9 @@
int i915_gem_dumb_create(struct drm_file *file_priv,
struct drm_device *dev,
struct drm_mode_create_dumb *args);
-int i915_gem_mmap_gtt(struct drm_file *file_priv, struct drm_device *dev,
- uint32_t handle, uint64_t *offset);
+int i915_gem_dumb_map_offset(struct drm_file *file_priv,
+ struct drm_device *dev, uint32_t handle,
+ uint64_t *offset);
/**
* Returns true if seq1 is later than seq2.
*/
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3e0cabe..50b8422 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -346,6 +346,7 @@
i915_gem_create(struct drm_file *file,
struct drm_device *dev,
uint64_t size,
+ bool dumb,
uint32_t *handle_p)
{
struct drm_i915_gem_object *obj;
@@ -361,6 +362,7 @@
if (obj == NULL)
return -ENOMEM;
+ obj->base.dumb = dumb;
ret = drm_gem_handle_create(file, &obj->base, &handle);
/* drop reference from allocate - handle holds it now */
drm_gem_object_unreference_unlocked(&obj->base);
@@ -380,7 +382,7 @@
args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
args->size = args->pitch * args->height;
return i915_gem_create(file, dev,
- args->size, &args->handle);
+ args->size, true, &args->handle);
}
/**
@@ -393,7 +395,7 @@
struct drm_i915_gem_create *args = data;
return i915_gem_create(file, dev,
- args->size, &args->handle);
+ args->size, false, &args->handle);
}
static inline int
@@ -1773,10 +1775,10 @@
drm_gem_free_mmap_offset(&obj->base);
}
-int
+static int
i915_gem_mmap_gtt(struct drm_file *file,
struct drm_device *dev,
- uint32_t handle,
+ uint32_t handle, bool dumb,
uint64_t *offset)
{
struct drm_i915_private *dev_priv = dev->dev_private;
@@ -1793,6 +1795,13 @@
goto unlock;
}
+ /*
+ * We don't allow dumb mmaps on objects created using another
+ * interface.
+ */
+ WARN_ONCE(dumb && !(obj->base.dumb || obj->base.import_attach),
+ "Illegal dumb map of accelerated buffer.\n");
+
if (obj->base.size > dev_priv->gtt.mappable_end) {
ret = -E2BIG;
goto out;
@@ -1817,6 +1826,15 @@
return ret;
}
+int
+i915_gem_dumb_map_offset(struct drm_file *file,
+ struct drm_device *dev,
+ uint32_t handle,
+ uint64_t *offset)
+{
+ return i915_gem_mmap_gtt(file, dev, handle, true, offset);
+}
+
/**
* i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
* @dev: DRM device
@@ -1838,7 +1856,7 @@
{
struct drm_i915_gem_mmap_gtt *args = data;
- return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset);
+ return i915_gem_mmap_gtt(file, dev, args->handle, false, &args->offset);
}
static inline int
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index e1ed85a..2b02fcf 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -121,6 +121,9 @@
goto err;
}
+ WARN_ONCE(obj->base.dumb,
+ "GPU use of dumb buffer is illegal.\n");
+
drm_gem_object_reference(&obj->base);
list_add_tail(&obj->obj_exec_link, &objects);
}