gru: fix prefetch and speculation bugs
Fix several bugs related to prefetch, ordering & speculation:
- GRU cch_allocate() instruction causes cacheable memory
to be created. Add a barriers to prevent speculation
from prefetching data before it exists.
- Add memory barriers before cache-flush instructions to ensure
that previously stored data is included in the line flushed to memory.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/misc/sgi-gru/gruhandles.c b/drivers/misc/sgi-gru/gruhandles.c
index 806419a..f1117a7 100644
--- a/drivers/misc/sgi-gru/gruhandles.c
+++ b/drivers/misc/sgi-gru/gruhandles.c
@@ -91,9 +91,18 @@
int cch_allocate(struct gru_context_configuration_handle *cch)
{
+ int ret;
+
cch->opc = CCHOP_ALLOCATE;
start_instruction(cch);
- return wait_instruction_complete(cch, cchop_allocate);
+ ret = wait_instruction_complete(cch, cchop_allocate);
+
+ /*
+ * Stop speculation into the GSEG being mapped by the previous ALLOCATE.
+ * The GSEG memory does not exist until the ALLOCATE completes.
+ */
+ sync_core();
+ return ret;
}
int cch_start(struct gru_context_configuration_handle *cch)
@@ -112,9 +121,18 @@
int cch_deallocate(struct gru_context_configuration_handle *cch)
{
+ int ret;
+
cch->opc = CCHOP_DEALLOCATE;
start_instruction(cch);
- return wait_instruction_complete(cch, cchop_deallocate);
+ ret = wait_instruction_complete(cch, cchop_deallocate);
+
+ /*
+ * Stop speculation into the GSEG being unmapped by the previous
+ * DEALLOCATE.
+ */
+ sync_core();
+ return ret;
}
int cch_interrupt_sync(struct gru_context_configuration_handle