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drm/i915: Only copy back the modified fields to userspace from execbuffer 

We only want to modifiy a single field in the userspace view of the
execbuffer command buffer, so explicitly change that rather than copy
everything back again.

This serves two purposes:

1. The single fields are much cheaper to copy (constant size so the
copy uses special case code) and much smaller than the whole array.

2. We modify the array for internal use that need to be masked from
the user.

Note: We need this backported since without it the next bugfix will
blow up when userspace recycles batchbuffers and relocations.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Chris Wilson 2014-05-23 10:45:52 +01:00 committed by Jani Nikula
parent 00731155a7
commit 9aab8bff7a
1 changed files with 32 additions and 22 deletions
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54
drivers/gpu/drm/i915/i915_gem_execbuffer.c
View File

@ -773,9 +773,9 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
* relocations were valid. * relocations were valid.
*/ */
for (j = 0; j < exec[i].relocation_count; j++) { for (j = 0; j < exec[i].relocation_count; j++) {
if (copy_to_user(&user_relocs[j].presumed_offset, if (__copy_to_user(&user_relocs[j].presumed_offset,
&invalid_offset, &invalid_offset,
sizeof(invalid_offset))) { sizeof(invalid_offset))) {
ret = -EFAULT; ret = -EFAULT;
mutex_lock(&dev->struct_mutex); mutex_lock(&dev->struct_mutex);
goto err; goto err;
@ -1355,18 +1355,21 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
ret = i915_gem_do_execbuffer(dev, data, file, &exec2, exec2_list); ret = i915_gem_do_execbuffer(dev, data, file, &exec2, exec2_list);
if (!ret) { if (!ret) {
struct drm_i915_gem_exec_object __user *user_exec_list =
to_user_ptr(args->buffers_ptr);
/* Copy the new buffer offsets back to the user's exec list. */ /* Copy the new buffer offsets back to the user's exec list. */
for (i = 0; i < args->buffer_count; i++) for (i = 0; i < args->buffer_count; i++) {
exec_list[i].offset = exec2_list[i].offset; ret = __copy_to_user(&user_exec_list[i].offset,
/* ... and back out to userspace */ &exec2_list[i].offset,
ret = copy_to_user(to_user_ptr(args->buffers_ptr), sizeof(user_exec_list[i].offset));
exec_list, if (ret) {
sizeof(*exec_list) * args->buffer_count); ret = -EFAULT;
if (ret) { DRM_DEBUG("failed to copy %d exec entries "
ret = -EFAULT; "back to user (%d)\n",
DRM_DEBUG("failed to copy %d exec entries " args->buffer_count, ret);
"back to user (%d)\n", break;
args->buffer_count, ret); }
} }
} }
@ -1412,14 +1415,21 @@ i915_gem_execbuffer2(struct drm_device *dev, void *data,
ret = i915_gem_do_execbuffer(dev, data, file, args, exec2_list); ret = i915_gem_do_execbuffer(dev, data, file, args, exec2_list);
if (!ret) { if (!ret) {
/* Copy the new buffer offsets back to the user's exec list. */ /* Copy the new buffer offsets back to the user's exec list. */
ret = copy_to_user(to_user_ptr(args->buffers_ptr), struct drm_i915_gem_exec_object2 *user_exec_list =
exec2_list, to_user_ptr(args->buffers_ptr);
sizeof(*exec2_list) * args->buffer_count); int i;
if (ret) {
ret = -EFAULT; for (i = 0; i < args->buffer_count; i++) {
DRM_DEBUG("failed to copy %d exec entries " ret = __copy_to_user(&user_exec_list[i].offset,
"back to user (%d)\n", &exec2_list[i].offset,
args->buffer_count, ret); sizeof(user_exec_list[i].offset));
if (ret) {
ret = -EFAULT;
DRM_DEBUG("failed to copy %d exec entries "
"back to user\n",
args->buffer_count);
break;
}
} }
} }