[POWERPC] spufs: serialize SLB invalidation against SLB loading

There is a potential race between flushes of the entire SLB in the MFC
and the point where new entries are being established. The problem is
that we might put a ESID entry into the MFC SLB when the VSID entry has
just been cleared by the global flush.

This can be circumvented by holding the register_lock throughout both
the flushing and the creation of SLB entries.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

arch/powerpc/platforms/cell/spu_base.c

@@ -81,9 +81,12 @@ struct spu_slb {
 void spu_invalidate_slbs(struct spu *spu)
 {
 	struct spu_priv2 __iomem *priv2 = spu->priv2;
+	unsigned long flags;
 
+	spin_lock_irqsave(&spu->register_lock, flags);
 	if (spu_mfc_sr1_get(spu) & MFC_STATE1_RELOCATE_MASK)
 		out_be64(&priv2->slb_invalidate_all_W, 0UL);
+	spin_unlock_irqrestore(&spu->register_lock, flags);
 }
 EXPORT_SYMBOL_GPL(spu_invalidate_slbs);
 
@@ -294,9 +297,11 @@ void spu_setup_kernel_slbs(struct spu *spu, struct spu_lscsa *lscsa,
 		nr_slbs++;
 	}
 
+	spin_lock_irq(&spu->register_lock);
 	/* Add the set of SLBs */
 	for (i = 0; i < nr_slbs; i++)
 		spu_load_slb(spu, i, &slbs[i]);
+	spin_unlock_irq(&spu->register_lock);
 }
 EXPORT_SYMBOL_GPL(spu_setup_kernel_slbs);
 
@@ -341,13 +346,14 @@ spu_irq_class_1(int irq, void *data)
 	if (stat & CLASS1_STORAGE_FAULT_INTR)
 		spu_mfc_dsisr_set(spu, 0ul);
 	spu_int_stat_clear(spu, 1, stat);
-	spin_unlock(&spu->register_lock);
-	pr_debug("%s: %lx %lx %lx %lx\n", __FUNCTION__, mask, stat,
-			dar, dsisr);
 
 	if (stat & CLASS1_SEGMENT_FAULT_INTR)
 		__spu_trap_data_seg(spu, dar);
 
+	spin_unlock(&spu->register_lock);
+	pr_debug("%s: %lx %lx %lx %lx\n", __FUNCTION__, mask, stat,
+			dar, dsisr);
+
 	if (stat & CLASS1_STORAGE_FAULT_INTR)
 		__spu_trap_data_map(spu, dar, dsisr);