Though less likely in practice, igt uses MI_NOOP frequently to pad out
its the batch buffers. The lookup and valiation of the MI_NOOP command
description is noticeable, though the side-effect of poisoning the
last-validate-command cache is more likely to impact upon real CS.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_cmd_parser.c | 58 +++++++++++++-------------
1 file changed, 30 insertions(+), 28 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c
b/drivers/gpu/drm/i915/i915_cmd_parser.c
index e88970256e8e..20014663cd5e 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -1453,42 +1453,44 @@ int intel_engine_cmd_parser(struct intel_engine_cs
*engine,
*/
batch_end = cmd + batch_length / sizeof(*batch_end);
do {
- u32 length;
+ u32 length = 1;
if (*cmd == MI_BATCH_BUFFER_END)
break;
- desc = find_cmd(engine, *cmd, desc, &default_desc);
- if (!desc) {
- DRM_DEBUG("CMD: Unrecognized command: 0x%08X\n", *cmd);
- ret = -EINVAL;
- break;
- }
+ if (*cmd) {
+ desc = find_cmd(engine, *cmd, desc, &default_desc);
+ if (!desc) {
+ DRM_DEBUG("CMD: Unrecognized command:
0x%08X\n", *cmd);
+ ret = -EINVAL;
+ break;
+ }
- if (desc->flags & CMD_DESC_FIXED)
- length = desc->length.fixed;
- else
- length = (*cmd & desc->length.mask) + LENGTH_BIAS;
+ if (desc->flags & CMD_DESC_FIXED)
+ length = desc->length.fixed;
+ else
+ length = (*cmd & desc->length.mask) +
LENGTH_BIAS;
- if ((batch_end - cmd) < length) {
- DRM_DEBUG("CMD: Command length exceeds batch length:
0x%08X length=%u batchlen=%td\n",
- *cmd,
- length,
- batch_end - cmd);
- ret = -EINVAL;
- break;
- }
+ if ((batch_end - cmd) < length) {
+ DRM_DEBUG("CMD: Command length exceeds batch
length: 0x%08X length=%u batchlen=%td\n",
+ *cmd,
+ length,
+ batch_end - cmd);
+ ret = -EINVAL;
+ break;
+ }
- if (!check_cmd(engine, desc, cmd, length)) {
- ret = -EACCES;
- break;
- }
+ if (!check_cmd(engine, desc, cmd, length)) {
+ ret = -EACCES;
+ break;
+ }
- if (cmd_desc_is(desc, MI_BATCH_BUFFER_START)) {
- ret = check_bbstart(cmd, offset, length, batch_length,
- batch_addr, shadow_addr,
- jump_whitelist);
- break;
+ if (cmd_desc_is(desc, MI_BATCH_BUFFER_START)) {
+ ret = check_bbstart(cmd, offset, length,
batch_length,
+ batch_addr, shadow_addr,
+ jump_whitelist);
+ break;
+ }
}
if (!IS_ERR_OR_NULL(jump_whitelist))
--
2.20.1
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