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>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
index 24ec109e61cc..8c81aca0463a 100644
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -395,6 +395,7 @@ int gru_get_cb_exception_detail(void *cb,
 	cbrnum = thread_cbr_number(bs->bs_kgts, get_cb_number(cb));
 	cbe = get_cbe(GRUBASE(cb), cbrnum);
 	gru_flush_cache(cbe);	/* CBE not coherent */
+	sync_core();
 	excdet->opc = cbe->opccpy;
 	excdet->exopc = cbe->exopccpy;
 	excdet->ecause = cbe->ecause;
@@ -461,9 +462,10 @@ int gru_check_status_proc(void *cb)
 	int ret;
 
 	ret = gen->istatus;
-	if (ret != CBS_EXCEPTION)
-		return ret;
-	return gru_retry_exception(cb);
+	if (ret == CBS_EXCEPTION)
+		ret = gru_retry_exception(cb);
+	rmb();
+	return ret;
 
 }
 
@@ -475,7 +477,7 @@ int gru_wait_proc(void *cb)
 	ret = gru_wait_idle_or_exception(gen);
 	if (ret == CBS_EXCEPTION)
 		ret = gru_retry_exception(cb);
-
+	rmb();
 	return ret;
 }