gru: fix cache coherency issues with instruction retry

Fix two problems related to GRU instruction failures.  Cache coherency is
not maintained for CBEs except when loading or unloading contexts.  When
reading a CBE to extract error information, the CBE must first be flushed
from the cache.

The function that reads kerrnel CBEs was reading the wrong CBE.

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, 1 deletions

diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index a489807613f8..6d0681236db5 100644
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -614,7 +614,7 @@ int gru_get_exception_detail(unsigned long arg)
         } else if (gts->ts_gru) {
                 cbrnum = thread_cbr_number(gts, ucbnum);
                 cbe = get_cbe_by_index(gts->ts_gru, cbrnum);
-                prefetchw(cbe);/* Harmless on hardware, required for emulator */
+                gru_flush_cache(cbe);   /* CBE not coherent */
                 excdet.opc = cbe->opccpy;
                 excdet.exopc = cbe->exopccpy;
                 excdet.ecause = cbe->ecause;
@@ -622,6 +622,7 @@ int gru_get_exception_detail(unsigned long arg)
                 excdet.exceptdet1 = cbe->idef3upd;
                 excdet.cbrstate = cbe->cbrstate;
                 excdet.cbrexecstatus = cbe->cbrexecstatus;
+                gru_flush_cache(cbe);
                 ret = 0;
         } else {
                 ret = -EAGAIN;