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arm64: fix unreachable code issue with cmpxchg 

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.

Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/648
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Tested-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Arnd Bergmann 2019-09-10 13:56:22 +02:00 committed by Will Deacon
parent e376897f42
commit 920fdab7b3
1 changed files with 3 additions and 3 deletions
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6
arch/arm64/include/asm/cmpxchg.h
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@ -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) \
{ \
@ -148,7 +148,7 @@ __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) \
@ -255,7 +255,7 @@ __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) \
{ \