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From:   Arnd Bergmann <arnd@arndb.de>
To:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Andrew Murray <andrew.murray@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com
Subject: [PATCH] arm64: fix unreachable code issue with cmpxchg
Date:   Mon,  9 Sep 2019 22:21:35 +0200
Message-Id: <20190909202153.144970-1-arnd@arndb.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On arm64 build with clang, sometimes the __cmpxchg_mb is not inlined
when CONFIG_OPTIMIZE_INLINING is set.
Clang then fails a compile-time assertion, because it cannot tell at
compile time what the size of the argument is:

mm/memcontrol.o: In function `__cmpxchg_mb':
memcontrol.c:(.text+0x1a4c): undefined reference to `__compiletime_assert_175'
memcontrol.c:(.text+0x1a4c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `__compiletime_assert_175'

Mark all of the cmpxchg() style functions as __always_inline to
ensure that the compiler can see the result.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm64/include/asm/cmpxchg.h | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
index a1398f2f9994..fd64dc8a235f 100644
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -19,7 +19,7 @@
  * acquire+release for the latter.
  */
 #define __XCHG_CASE(w, sfx, name, sz, mb, nop_lse, acq, acq_lse, rel, cl)	\
-static inline u##sz __xchg_case_##name##sz(u##sz x, volatile void *ptr)		\
+static __always_inline u##sz __xchg_case_##name##sz(u##sz x, volatile void *ptr)\
 {										\
 	u##sz ret;								\
 	unsigned long tmp;							\
@@ -62,7 +62,7 @@ __XCHG_CASE( ,  ,  mb_, 64, dmb ish, nop,  , a, l, "memory")
 #undef __XCHG_CASE
 
 #define __XCHG_GEN(sfx)							\
-static inline unsigned long __xchg##sfx(unsigned long x,		\
+static __always_inline  unsigned long __xchg##sfx(unsigned long x,	\
 					volatile void *ptr,		\
 					int size)			\
 {									\
@@ -103,8 +103,9 @@ __XCHG_GEN(_mb)
 #define arch_xchg_release(...)	__xchg_wrapper(_rel, __VA_ARGS__)
 #define arch_xchg(...)		__xchg_wrapper( _mb, __VA_ARGS__)
 
-#define __CMPXCHG_CASE(name, sz)			\
-static inline u##sz __cmpxchg_case_##name##sz(volatile void *ptr,	\
+#define __CMPXCHG_CASE(name, sz)					\
+static __always_inline u##sz 						\
+__cmpxchg_case_##name##sz(volatile void *ptr,				\
 					      u##sz old,		\
 					      u##sz new)		\
 {									\
@@ -148,7 +149,7 @@ __CMPXCHG_DBL(_mb)
 #undef __CMPXCHG_DBL
 
 #define __CMPXCHG_GEN(sfx)						\
-static inline unsigned long __cmpxchg##sfx(volatile void *ptr,		\
+static __always_inline unsigned long __cmpxchg##sfx(volatile void *ptr,	\
 					   unsigned long old,		\
 					   unsigned long new,		\
 					   int size)			\
@@ -230,7 +231,7 @@ __CMPXCHG_GEN(_mb)
 })
 
 #define __CMPWAIT_CASE(w, sfx, sz)					\
-static inline void __cmpwait_case_##sz(volatile void *ptr,		\
+static __always_inline void __cmpwait_case_##sz(volatile void *ptr,	\
 				       unsigned long val)		\
 {									\
 	unsigned long tmp;						\
@@ -255,7 +256,7 @@ __CMPWAIT_CASE( ,  , 64);
 #undef __CMPWAIT_CASE
 
 #define __CMPWAIT_GEN(sfx)						\
-static inline void __cmpwait##sfx(volatile void *ptr,			\
+static __always_inline void __cmpwait##sfx(volatile void *ptr,		\
 				  unsigned long val,			\
 				  int size)				\
 {									\
-- 
2.20.0