queue/sparc64-fix-fault-handling-in-NGbzero.S-and-GENbzero.patch

From 3c7f62212018b904ae17f5636ead18a4dca3a88f Mon Sep 17 00:00:00 2001
From: Dave Aldridge <david.j.aldridge@oracle.com>
Date: Tue, 9 May 2017 02:57:35 -0600
Subject: [PATCH] sparc64: fix fault handling in NGbzero.S and GENbzero.S

commit 3c7f62212018b904ae17f5636ead18a4dca3a88f upstream.

When any of the functions contained in NGbzero.S and GENbzero.S
vector through *bzero_from_clear_user, we may end up taking a
fault when executing one of the store alternate address space
instructions. If this happens, the exception handler does not
restore the %asi register.

This commit fixes the issue by introducing a new exception
handler that ensures the %asi register is restored when
a fault is handled.

Orabug: 25577560

Signed-off-by: Dave Aldridge <david.j.aldridge@oracle.com>
Reviewed-by: Rob Gardner <rob.gardner@oracle.com>
Reviewed-by: Babu Moger <babu.moger@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
index 44101196d02b..41a407328667 100644
--- a/arch/sparc/kernel/head_64.S
+++ b/arch/sparc/kernel/head_64.S
@@ -939,3 +939,9 @@ ENTRY(__retl_o1)
 	retl
 	 mov	%o1, %o0
 ENDPROC(__retl_o1)
+
+ENTRY(__retl_o1_asi)
+	wr      %o5, 0x0, %asi
+	retl
+	 mov    %o1, %o0
+ENDPROC(__retl_o1_asi)
diff --git a/arch/sparc/lib/GENbzero.S b/arch/sparc/lib/GENbzero.S
index 8e7a843ddd88..2fbf6297d57c 100644
--- a/arch/sparc/lib/GENbzero.S
+++ b/arch/sparc/lib/GENbzero.S
@@ -8,7 +8,7 @@
 98:	x,y;			\
 	.section __ex_table,"a";\
 	.align 4;		\
-	.word 98b, __retl_o1;	\
+	.word 98b, __retl_o1_asi;\
 	.text;			\
 	.align 4;
 
diff --git a/arch/sparc/lib/NGbzero.S b/arch/sparc/lib/NGbzero.S
index beab29bf419b..33053bdf3766 100644
--- a/arch/sparc/lib/NGbzero.S
+++ b/arch/sparc/lib/NGbzero.S
@@ -8,7 +8,7 @@
 98:	x,y;			\
 	.section __ex_table,"a";\
 	.align 4;		\
-	.word 98b, __retl_o1;	\
+	.word 98b, __retl_o1_asi;\
 	.text;			\
 	.align 4;
 
-- 
2.12.0