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From: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
To: linux-metag-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
Subject: [PATCH v2 9/9] metag/usercopy: Simplify rapf loop fixup corner case
Date: Wed, 5 Apr 2017 15:15:09 +0100	[thread overview]
Message-ID: <d90ff0d31c22a396da89dbaf5955007820861681.1491401555.git-series.james.hogan@imgtec.com> (raw)
In-Reply-To: <cover.9d8cef22e7d1fc48955098a7161938dfc3e50db7.1491401555.git-series.james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>

The final fixup in the rapf loops must handle a corner case due to the
intermediate decrementing of the destination pointer before writing the
last element to it again and re-incrementing it. This decrement (and the
associated increment in the fixup code) can be easily avoided by using
SETL/SETD with an offset of -8/-4.

Signed-off-by: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
Cc: linux-metag-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 arch/metag/lib/usercopy.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/metag/lib/usercopy.c b/arch/metag/lib/usercopy.c
index 7abed2f45c83..ceb4590fbca5 100644
--- a/arch/metag/lib/usercopy.c
+++ b/arch/metag/lib/usercopy.c
@@ -270,8 +270,7 @@
 		"29:	SUB	%3, %3, #32\n"				\
 		"30:	MGETL	D0FrT, D0.5, D0.6, D0.7, [%1++]\n"	\
 		"31:	MSETL	[%0++], D0FrT, D0.5, D0.6, D0.7\n"	\
-		"32:	SUB	%0, %0, #8\n"				\
-		"33:	SETL	[%0++], D0.7, D1.7\n"			\
+		"32:	SETL	[%0+#-8], D0.7, D1.7\n"			\
 		"	SUB	%3, %3, #32\n"				\
 		"1:	DCACHE	[%1+#-64], D0Ar6\n"			\
 		"	GETL	D0Ar6, D1Ar5, [A0StP+#-40]\n"		\
@@ -281,7 +280,6 @@
 		"	GETL	D0.7, D1.7, [A0StP+#-8]\n"		\
 		"	SUB	A0StP, A0StP, #40\n"			\
 		"	.section .fixup,\"ax\"\n"			\
-		"4:	ADD	%0, %0, #8\n"				\
 		"3:	MOV	D0Ar2, TXSTATUS\n"			\
 		"	MOV	D1Ar1, TXSTATUS\n"			\
 		"	AND	D1Ar1, D1Ar1, #0xFFFFF8FF\n"		\
@@ -303,7 +301,6 @@
 		"	.long 30b,3b\n"					\
 		"	.long 31b,3b\n"					\
 		"	.long 32b,3b\n"					\
-		"	.long 33b,4b\n"					\
 		"	.previous\n"					\
 		: "=r" (to), "=r" (from), "=r" (ret), "=d" (n)		\
 		: "0" (to), "1" (from), "2" (ret), "3" (n)		\
@@ -417,8 +414,7 @@
 		"41:	SUB	%3, %3, #16\n"				\
 		"42:	MGETD	D0FrT, D0.5, D0.6, D0.7, [%1++]\n"	\
 		"43:	MSETD	[%0++], D0FrT, D0.5, D0.6, D0.7\n"	\
-		"44:	SUB	%0, %0, #4\n"				\
-		"45:	SETD	[%0++], D0.7\n"				\
+		"44:	SETD	[%0+#-4], D0.7\n"			\
 		"	SUB	%3, %3, #16\n"				\
 		"1:	DCACHE	[%1+#-64], D0Ar6\n"			\
 		"	GETL	D0Ar6, D1Ar5, [A0StP+#-40]\n"		\
@@ -428,7 +424,6 @@
 		"	GETL	D0.7, D1.7, [A0StP+#-8]\n"		\
 		"	SUB A0StP, A0StP, #40\n"			\
 		"	.section .fixup,\"ax\"\n"			\
-		"4:	ADD	%0, %0, #4\n"				\
 		"3:	MOV	D0Ar2, TXSTATUS\n"			\
 		"	MOV	D1Ar1, TXSTATUS\n"			\
 		"	AND	D1Ar1, D1Ar1, #0xFFFFF8FF\n"		\
@@ -462,7 +457,6 @@
 		"	.long 42b,3b\n"					\
 		"	.long 43b,3b\n"					\
 		"	.long 44b,3b\n"					\
-		"	.long 45b,4b\n"					\
 		"	.previous\n"					\
 		: "=r" (to), "=r" (from), "=r" (ret), "=d" (n)		\
 		: "0" (to), "1" (from), "2" (ret), "3" (n)		\
-- 
git-series 0.8.10

      parent reply	other threads:[~2017-04-05 14:15 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-05 14:15 [PATCH v2 0/9] metag/usercopy: Fault handling fixes & cleanups James Hogan
2017-04-05 14:15 ` James Hogan
2017-04-05 14:15 ` [PATCH v2 1/9] metag/usercopy: Drop unused macros James Hogan
2017-04-05 14:15   ` James Hogan
2017-04-05 14:15 ` [PATCH v2 2/9] metag/usercopy: Fix alignment error checking James Hogan
2017-04-05 14:15   ` James Hogan
2017-04-05 14:15 ` [PATCH v2 3/9] metag/usercopy: Add early abort to copy_to_user James Hogan
2017-04-05 14:15   ` James Hogan
2017-04-05 14:15 ` [PATCH v2 4/9] metag/usercopy: Zero rest of buffer from copy_from_user James Hogan
2017-04-05 14:15   ` James Hogan
2017-04-05 14:15 ` [PATCH v2 5/9] metag/usercopy: Set flags before ADDZ James Hogan
2017-04-05 14:15   ` James Hogan
2017-04-05 14:15 ` [PATCH v2 6/9] metag/usercopy: Fix src fixup in from user rapf loops James Hogan
2017-04-05 14:15   ` James Hogan
2017-04-05 14:15 ` [PATCH v2 7/9] metag/usercopy: Add missing fixups James Hogan
2017-04-05 14:15   ` James Hogan
     [not found] ` <cover.9d8cef22e7d1fc48955098a7161938dfc3e50db7.1491401555.git-series.james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
2017-04-05 14:15   ` [PATCH v2 8/9] metag/usercopy: Reformat rapf loop inline asm James Hogan
2017-04-05 14:15   ` James Hogan [this message]

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