1 files changed, 22 insertions, 8 deletions

diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
index d9ff0289a1c3..c13342dda5fd 100644
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -97,9 +97,6 @@
 #define ASYNC_HAN_TO_BID(h)     ((h) - 1)
 #define ASYNC_BID_TO_HAN(b)     ((b) + 1)
 #define ASYNC_HAN_TO_BS(h)      gru_base[ASYNC_HAN_TO_BID(h)]
-#define KCB_TO_GID(cb)          ((cb - gru_start_vaddr) /               \
-                                        (GRU_SIZE * GRU_CHIPLETS_PER_BLADE))
-#define KCB_TO_BS(cb)           gru_base[KCB_TO_GID(cb)]
 
 #define GRU_NUM_KERNEL_CBR      1
 #define GRU_NUM_KERNEL_DSR_BYTES 256
@@ -388,11 +385,28 @@ int gru_get_cb_exception_detail(void *cb,
                 struct control_block_extended_exc_detail *excdet)
 {
         struct gru_control_block_extended *cbe;
-        struct gru_blade_state *bs;
-        int cbrnum;
-
-        bs = KCB_TO_BS(cb);
-        cbrnum = thread_cbr_number(bs->bs_kgts, get_cb_number(cb));
+        struct gru_thread_state *kgts = NULL;
+        unsigned long off;
+        int cbrnum, bid;
+
+        /*
+         * Locate kgts for cb. This algorithm is SLOW but
+         * this function is rarely called (ie., almost never).
+         * Performance does not matter.
+         */
+        for_each_possible_blade(bid) {
+                if (!gru_base[bid])
+                        break;
+                kgts = gru_base[bid]->bs_kgts;
+                if (!kgts || !kgts->ts_gru)
+                        continue;
+                off = cb - kgts->ts_gru->gs_gru_base_vaddr;
+                if (off < GRU_SIZE)
+                        break;
+                kgts = NULL;
+        }
+        BUG_ON(!kgts);
+        cbrnum = thread_cbr_number(kgts, get_cb_number(cb));
         cbe = get_cbe(GRUBASE(cb), cbrnum);
         gru_flush_cache(cbe);   /* CBE not coherent */
         sync_core();