From: Nick Desaulniers <ndesaulniers@google.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Andrew Murray <andrew.murray@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH] arm64: fix unreachable code issue with cmpxchg
Date: Mon, 9 Sep 2019 14:06:36 -0700 [thread overview]
Message-ID: <CAKwvOdn90naN2qLx6qBCii67HNOYeJmVqTKEKuUpXcTXLEEaLA@mail.gmail.com> (raw)
In-Reply-To: <20190909202153.144970-1-arnd@arndb.de>
On Mon, Sep 9, 2019 at 1:21 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> 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>
>
> 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
>
> --
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> To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20190909202153.144970-1-arnd%40arndb.de.
--
Thanks,
~Nick Desaulniers
next prev parent reply other threads:[~2019-09-09 21:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 20:21 [PATCH] arm64: fix unreachable code issue with cmpxchg Arnd Bergmann
2019-09-09 21:06 ` Nick Desaulniers [this message]
2019-09-09 21:35 ` Nick Desaulniers
2019-09-10 3:42 ` Nathan Chancellor
2019-09-10 7:46 ` Will Deacon
2019-09-10 8:04 ` Arnd Bergmann
2019-09-10 13:24 ` Will Deacon
2019-09-10 13:43 ` Arnd Bergmann
2019-09-10 14:21 ` Andrew Murray
2019-09-10 9:23 ` Andrew Murray
2019-09-10 9:38 ` Arnd Bergmann
2019-09-10 10:17 ` Masahiro Yamada
2019-09-10 10:24 ` Andrew Murray
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