linux-kernel - [PATCH v2 4/4] xtensa: initialize result in __get_user

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Message-Id: <20191012003708.22182-5-jcmvbkbc@gmail.com>
Date:   Fri, 11 Oct 2019 17:37:08 -0700
From:   Max Filippov <jcmvbkbc@...il.com>
To:     linux-xtensa@...ux-xtensa.org, Al Viro <viro@...iv.linux.org.uk>
Cc:     Chris Zankel <chris@...kel.net>, linux-kernel@...r.kernel.org,
        Max Filippov <jcmvbkbc@...il.com>
Subject: [PATCH v2 4/4] xtensa: initialize result in __get_user_asm for unaligned access

__get_user_asm macro leaves result register uninitialized when alignment
check fails. Add 'insn' parameter to __check_align_{1,2,4} and pass an
instruction that initializes result register from __get_user_asm.

Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
---
 arch/xtensa/include/asm/uaccess.h | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
index 43e923678dfb..d8cff972f3cf 100644
--- a/arch/xtensa/include/asm/uaccess.h
+++ b/arch/xtensa/include/asm/uaccess.h
@@ -129,17 +129,19 @@ do {									\
  * sync.
  */
 
-#define __check_align_1  ""
+#define __check_align_1(insn)  ""
 
-#define __check_align_2				\
+#define __check_align_2(insn)			\
 	"   _bbci.l %[addr], 0, 1f	\n"	\
 	"   movi    %[err], %[efault]	\n"	\
+	"   "insn"			\n"	\
 	"   _j      2f			\n"
 
-#define __check_align_4				\
+#define __check_align_4(insn)			\
 	"   _bbsi.l %[addr], 0, 0f	\n"	\
 	"   _bbci.l %[addr], 1, 1f	\n"	\
 	"0: movi    %[err], %[efault]	\n"	\
+	"   "insn"			\n"	\
 	"   _j      2f			\n"
 
 
@@ -153,7 +155,7 @@ do {									\
  */
 #define __put_user_asm(x_, addr_, err_, align, insn, cb)\
 __asm__ __volatile__(					\
-	__check_align_##align				\
+	__check_align_##align("")			\
 	"1: "insn"  %[x], %[addr], 0	\n"		\
 	"2:				\n"		\
 	"   .section  .fixup,\"ax\"	\n"		\
@@ -221,7 +223,7 @@ do {									\
 do {							\
 	u32 __x;					\
 	__asm__ __volatile__(				\
-		__check_align_##align			\
+		__check_align_##align("movi %[x], 0")	\
 		"1: "insn"  %[x], %[addr], 0	\n"	\
 		"2:				\n"	\
 		"   .section  .fixup,\"ax\"	\n"	\
-- 
2.20.1