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