From: George Beshers <gbeshers@redhat.com>
Date: Thu, 31 Jul 2008 15:33:34 -0400
Subject: [IA64] Force error to surface in nofault code
Message-id: 20080731192739.4411.10534.sendpatchset@dhcp-100-2-194.bos.redhat.com
O-Subject: [RHEL5.3 PATCH 11/19] [IA64] Force error to surface in nofault code
Bugzilla: 455308
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>

[patch] Force error to surface in nofault code

BZ#455308

Upstream: http://git.kernel.org/?p=linux/kernel/git/aegl/linux-2.6.git;a=commitdiff;h=45d9ca492e4bd1522d1b5bd125c2908f1cee3d4a

Montecito behaves slightly differently than previous processors,
resulting in the MCA due to a failed PIO read to sometimes surfacing
outside the nofault code.  Adding an additional or and stop bits
ensures the MCA surfaces in the nofault code.

Signed-off-by: Russ Anderson <rja@sgi.com>

diff --git a/arch/ia64/sn/kernel/xp_nofault.S b/arch/ia64/sn/kernel/xp_nofault.S
index b772543..6472ad5 100644
--- a/arch/ia64/sn/kernel/xp_nofault.S
+++ b/arch/ia64/sn/kernel/xp_nofault.S
@@ -3,7 +3,7 @@
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
- * Copyright (c) 2004-2005 Silicon Graphics, Inc.  All Rights Reserved.
+ * Copyright (c) 2004-2007 Silicon Graphics, Inc.  All Rights Reserved.
  */
 
 
@@ -14,6 +14,10 @@
  * PIO read fails, the MCA handler will force the error to look
  * corrected and vector to the xp_error_PIOR which will return an error.
  *
+ * The definition of "consumption" and the time it takes for an MCA
+ * to surface is processor implementation specific.  This code
+ * may need to be adjusted for future processor implementations.
+ *
  *	extern int xp_nofault_PIOR(void *remote_register);
  */
 
@@ -21,7 +25,8 @@
 xp_nofault_PIOR:
 	mov	r8=r0			// Stage a success return value
 	ld8.acq	r9=[r32];;		// PIO Read the specified register
-	adds	r9=1,r9			// Add to force a consume
+	adds	r9=1,r9;;		// Add to force a consume
+	srlz.i;;			// Allow time for MCA to surface
 	br.ret.sptk.many b0;;		// Return success
 
 	.global xp_error_PIOR