From: Brad Peters <bpeters@redhat.com>
Date: Fri, 7 Mar 2008 18:19:07 -0500
Subject: [ppc64] SLB: serialize invalidation against loading
Message-id: 47D1CD6B.4050304@redhat.com
O-Subject: [RHEL 5.2 Patch 1/2] Fix data corruption on SLB update - remove SLB flush race condition
Bugzilla: 436336

Subject: 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>

Acked-by: David Howells <dhowells@redhat.com>

diff --git a/arch/powerpc/platforms/cell/spu_base.c b/arch/powerpc/platforms/cell/spu_base.c
index 9c64e3d..425617b 100644
--- a/arch/powerpc/platforms/cell/spu_base.c
+++ b/arch/powerpc/platforms/cell/spu_base.c
@@ -71,9 +71,12 @@ static DEFINE_MUTEX(spu_full_list_mutex);
 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);
 
@@ -287,13 +290,14 @@ spu_irq_class_1(int irq, void *data, struct pt_regs *regs)
 	if (stat & 2) /* mapping fault */
 		spu_mfc_dsisr_set(spu, 0ul);
 	spu_int_stat_clear(spu, 1, stat);
+	if (stat & 1) /* segment fault */
+		__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 & 1) /* segment fault */
-		__spu_trap_data_seg(spu, dar);
-
 	if (stat & 2) { /* mapping fault */
 		__spu_trap_data_map(spu, dar, dsisr);
 	}