linux-kernel - [PATCH 3.10 204/250] metag/usercopy: Set flags before ADDZ

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Message-Id: <1496876436-32402-205-git-send-email-w@1wt.eu>
Date:   Thu,  8 Jun 2017 00:59:50 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     James Hogan <james.hogan@...tec.com>, linux-metag@...r.kernel.org,
        Jiri Slaby <jslaby@...e.cz>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 204/250] metag/usercopy: Set flags before ADDZ

From: James Hogan <james.hogan@...tec.com>

commit fd40eee1290ad7add7aa665e3ce6b0f9fe9734b4 upstream.

The fixup code for the copy_to_user rapf loops reads TXStatus.LSM_STEP
to decide how far to rewind the source pointer. There is a special case
for the last execution of an MGETL/MGETD, since it leaves LSM_STEP=0
even though the number of MGETLs/MGETDs attempted was 4. This uses ADDZ
which is conditional upon the Z condition flag, but the AND instruction
which masked the TXStatus.LSM_STEP field didn't set the condition flags
based on the result.

Fix that now by using ANDS which does set the flags, and also marking
the condition codes as clobbered by the inline assembly.

Fixes: 373cd784d0fc ("metag: Memory handling")
Signed-off-by: James Hogan <james.hogan@...tec.com>
Cc: linux-metag@...r.kernel.org
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Signed-off-by: Willy Tarreau <w@....eu>
---
 arch/metag/lib/usercopy.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/metag/lib/usercopy.c b/arch/metag/lib/usercopy.c
index 212c99a..c3697a1 100644
--- a/arch/metag/lib/usercopy.c
+++ b/arch/metag/lib/usercopy.c
@@ -316,7 +316,7 @@
 		"	.previous\n"					\
 		: "=r" (to), "=r" (from), "=r" (ret), "=d" (n)		\
 		: "0" (to), "1" (from), "2" (ret), "3" (n)		\
-		: "D1Ar1", "D0Ar2", "memory")
+		: "D1Ar1", "D0Ar2", "cc", "memory")
 
 /*	rewind 'to' and 'from'  pointers when a fault occurs
  *
@@ -342,7 +342,7 @@
 #define __asm_copy_to_user_64bit_rapf_loop(to,	from, ret, n, id)\
 	__asm_copy_user_64bit_rapf_loop(to, from, ret, n, id,		\
 		"LSR	D0Ar2, D0Ar2, #8\n"				\
-		"AND	D0Ar2, D0Ar2, #0x7\n"				\
+		"ANDS	D0Ar2, D0Ar2, #0x7\n"				\
 		"ADDZ	D0Ar2, D0Ar2, #4\n"				\
 		"SUB	D0Ar2, D0Ar2, #1\n"				\
 		"MOV	D1Ar1, #4\n"					\
@@ -487,7 +487,7 @@
 		"	.previous\n"					\
 		: "=r" (to), "=r" (from), "=r" (ret), "=d" (n)		\
 		: "0" (to), "1" (from), "2" (ret), "3" (n)		\
-		: "D1Ar1", "D0Ar2", "memory")
+		: "D1Ar1", "D0Ar2", "cc", "memory")
 
 /*	rewind 'to' and 'from'  pointers when a fault occurs
  *
@@ -513,7 +513,7 @@
 #define __asm_copy_to_user_32bit_rapf_loop(to, from, ret, n, id)\
 	__asm_copy_user_32bit_rapf_loop(to, from, ret, n, id,		\
 		"LSR	D0Ar2, D0Ar2, #8\n"				\
-		"AND	D0Ar2, D0Ar2, #0x7\n"				\
+		"ANDS	D0Ar2, D0Ar2, #0x7\n"				\
 		"ADDZ	D0Ar2, D0Ar2, #4\n"				\
 		"SUB	D0Ar2, D0Ar2, #1\n"				\
 		"MOV	D1Ar1, #4\n"					\
-- 
2.8.0.rc2.1.gbe9624a