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, 2 insertions, 0 deletions

diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index 7466234450f3..d3cacd696b38 100644
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -333,6 +333,7 @@ static int gru_try_dropin(struct gru_thread_state *gts,
          */
         if (tfh->status != TFHSTATUS_EXCEPTION) {
                 gru_flush_cache(tfh);
+                sync_core();
                 if (tfh->status != TFHSTATUS_EXCEPTION)
                         goto failnoexception;
                 STAT(tfh_stale_on_fault);
@@ -599,6 +600,7 @@ int gru_get_exception_detail(unsigned long arg)
                 cbrnum = thread_cbr_number(gts, ucbnum);
                 cbe = get_cbe_by_index(gts->ts_gru, cbrnum);
                 gru_flush_cache(cbe);   /* CBE not coherent */
+                sync_core();            /* make sure we are have current data */
                 excdet.opc = cbe->opccpy;
                 excdet.exopc = cbe->exopccpy;
                 excdet.ecause = cbe->ecause;