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    Subject[PATCH AUTOSEL 5.2 58/70] arm64: fix unreachable code issue with cmpxchg
    Date
    From: Arnd Bergmann <arnd@arndb.de>

    [ Upstream commit 920fdab7b3ce98c14c840261e364f490f3679a62 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/arm64/include/asm/cmpxchg.h | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
    index 7a299a20f6dcc..7a8b8bc69e8d1 100644
    --- a/arch/arm64/include/asm/cmpxchg.h
    +++ b/arch/arm64/include/asm/cmpxchg.h
    @@ -63,7 +63,7 @@ __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) \
    { \
    @@ -105,7 +105,7 @@ __XCHG_GEN(_mb)
    #define arch_xchg(...) __xchg_wrapper( _mb, __VA_ARGS__)

    #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) \
    @@ -212,7 +212,7 @@ __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) \
    { \
    --
    2.20.1
    \
     
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