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/grumain.c b/drivers/misc/sgi-gru/grumain.c
index 9440288..a383271 100644
--- a/drivers/misc/sgi-gru/grumain.c
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -499,6 +499,9 @@
memset(cbe + i * GRU_HANDLE_STRIDE, 0,
GRU_CACHE_LINE_BYTES);
}
+ /* Flush CBE to hide race in context restart */
+ mb();
+ gru_flush_cache(cbe + i * GRU_HANDLE_STRIDE);
cb += GRU_HANDLE_STRIDE;
}
@@ -519,6 +522,12 @@
cb = gseg + GRU_CB_BASE;
cbe = grubase + GRU_CBE_BASE;
length = hweight64(dsrmap) * GRU_DSR_AU_BYTES;
+
+ /* CBEs may not be coherent. Flush them from cache */
+ for_each_cbr_in_allocation_map(i, &cbrmap, scr)
+ gru_flush_cache(cbe + i * GRU_HANDLE_STRIDE);
+ mb(); /* Let the CL flush complete */
+
gru_prefetch_context(gseg, cb, cbe, cbrmap, length);
for_each_cbr_in_allocation_map(i, &cbrmap, scr) {