[PATCH V4 1/1] ARM : missing corrupted reg in __div64_32

[chengang.beijing@outlook.com (chengang)]

__xl(R0 in little endian system, or R1 in big endian system) is corrupted
by the call to  __do_div64i(). The  compiler is not aware of this, so if
n is used afterwards __xl won't be reloaded and n will contain incorrect value.

Mark 64bits variable __n as inputi/output to inform compiler both r0 and r1
are changed by the funciton call.

Signed-off-by: Chen Gang <gangchen@rdamicro.com>
Signed-off-by: Chen Gang <changeang.beijing@outlook.com>
---
 arch/arm/include/asm/div64.h | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
index e1f0776..1153e6d 100644
--- a/arch/arm/include/asm/div64.h
+++ b/arch/arm/include/asm/div64.h
@@ -21,30 +21,24 @@
  * for arguments and results (beware).
  */
 
-#ifdef __ARMEB__
-#define __xh "r0"
-#define __xl "r1"
-#else
-#define __xl "r0"
-#define __xh "r1"
-#endif
 
 static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
 {
 	register unsigned int __base      asm("r4") = base;
 	register unsigned long long __n   asm("r0") = *n;
 	register unsigned long long __res asm("r2");
-	register unsigned int __rem       asm(__xh);
-	asm(	__asmeq("%0", __xh)
+	asm(	__asmeq("%0", "r0")
 		__asmeq("%1", "r2")
-		__asmeq("%2", "r0")
-		__asmeq("%3", "r4")
+		__asmeq("%2", "r4")
 		"bl	__do_div64"
-		: "=r" (__rem), "=r" (__res)
-		: "r" (__n), "r" (__base)
+		: "+r" (__n), "=r" (__res)
+		: "r" (__base)
 		: "ip", "lr", "cc");
 	*n = __res;
-	return __rem;
+	/*
+	 * __do_div64 returns the remainder in the upper word of __n
+	 */
+	return __n >> 32;
 }
 #define __div64_32 __div64_32
 
-- 
2.4.3