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* [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg
@ 2019-09-10 11:56 Arnd Bergmann
  2019-09-17 20:34 ` Nathan Chancellor
  0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2019-09-10 11:56 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon
  Cc: Arnd Bergmann, Nick Desaulniers, Nathan Chancellor,
	Andrew Murray, Thomas Gleixner, Peter Zijlstra (Intel),
	Mark Rutland, linux-arm-kernel, linux-kernel, clang-built-linux

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>
---
v2: skip unneeded changes, as suggested by Andrew Murray
---
 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 a1398f2f9994..f9bef42c1411 100644
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -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)				\
 {									\
-- 
2.20.0


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg
  2019-09-10 11:56 [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg Arnd Bergmann
@ 2019-09-17 20:34 ` Nathan Chancellor
  2019-09-18  9:02   ` Will Deacon
  0 siblings, 1 reply; 4+ messages in thread
From: Nathan Chancellor @ 2019-09-17 20:34 UTC (permalink / raw)
  To: Arnd Bergmann
  Cc: Catalin Marinas, Will Deacon, Nick Desaulniers, Andrew Murray,
	Thomas Gleixner, Peter Zijlstra (Intel),
	Mark Rutland, linux-arm-kernel, linux-kernel, clang-built-linux

On Tue, Sep 10, 2019 at 01:56:22PM +0200, Arnd Bergmann 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>
> 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>
> ---
> v2: skip unneeded changes, as suggested by Andrew Murray
> ---
>  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 a1398f2f9994..f9bef42c1411 100644
> --- a/arch/arm64/include/asm/cmpxchg.h
> +++ b/arch/arm64/include/asm/cmpxchg.h
> @@ -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)				\
>  {									\
> -- 
> 2.20.0
> 

Looks like the arm64 pull request happened without this patch so clang
all{mod,yes}config builds are broken. Did the maintainers have any
further comments on it or could this make it in with the next one?

Cheers,
Nathan

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg
  2019-09-17 20:34 ` Nathan Chancellor
@ 2019-09-18  9:02   ` Will Deacon
  2019-09-18 16:02     ` Nathan Chancellor
  0 siblings, 1 reply; 4+ messages in thread
From: Will Deacon @ 2019-09-18  9:02 UTC (permalink / raw)
  To: Nathan Chancellor
  Cc: Arnd Bergmann, Catalin Marinas, Nick Desaulniers, Andrew Murray,
	Thomas Gleixner, Peter Zijlstra (Intel),
	Mark Rutland, linux-arm-kernel, linux-kernel, clang-built-linux

On Tue, Sep 17, 2019 at 01:34:25PM -0700, Nathan Chancellor wrote:
> On Tue, Sep 10, 2019 at 01:56:22PM +0200, Arnd Bergmann 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>
> > 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>
> > ---
> > v2: skip unneeded changes, as suggested by Andrew Murray
> > ---
> >  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 a1398f2f9994..f9bef42c1411 100644
> > --- a/arch/arm64/include/asm/cmpxchg.h
> > +++ b/arch/arm64/include/asm/cmpxchg.h
> > @@ -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)				\
> >  {									\
> > -- 
> > 2.20.0
> > 
> 
> Looks like the arm64 pull request happened without this patch so clang
> all{mod,yes}config builds are broken. Did the maintainers have any
> further comments on it or could this make it in with the next one?

Fear not! I plan to send this with some other fixes we've got for -rc1.
I just to get my CI scripts going again (new machine), but that shouldn't
take long.

Will

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg
  2019-09-18  9:02   ` Will Deacon
@ 2019-09-18 16:02     ` Nathan Chancellor
  0 siblings, 0 replies; 4+ messages in thread
From: Nathan Chancellor @ 2019-09-18 16:02 UTC (permalink / raw)
  To: Will Deacon
  Cc: Arnd Bergmann, Catalin Marinas, Nick Desaulniers, Andrew Murray,
	Thomas Gleixner, Peter Zijlstra (Intel),
	Mark Rutland, linux-arm-kernel, linux-kernel, clang-built-linux

On Wed, Sep 18, 2019 at 10:02:41AM +0100, Will Deacon wrote:
> On Tue, Sep 17, 2019 at 01:34:25PM -0700, Nathan Chancellor wrote:
> > On Tue, Sep 10, 2019 at 01:56:22PM +0200, Arnd Bergmann 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>
> > > 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>
> > > ---
> > > v2: skip unneeded changes, as suggested by Andrew Murray
> > > ---
> > >  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 a1398f2f9994..f9bef42c1411 100644
> > > --- a/arch/arm64/include/asm/cmpxchg.h
> > > +++ b/arch/arm64/include/asm/cmpxchg.h
> > > @@ -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)				\
> > >  {									\
> > > -- 
> > > 2.20.0
> > > 
> > 
> > Looks like the arm64 pull request happened without this patch so clang
> > all{mod,yes}config builds are broken. Did the maintainers have any
> > further comments on it or could this make it in with the next one?
> 
> Fear not! I plan to send this with some other fixes we've got for -rc1.
> I just to get my CI scripts going again (new machine), but that shouldn't
> take long.
> 
> Will

Great, thank you!

Cheers,
Nathan

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2019-09-18 16:02 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2019-09-10 11:56 [PATCH] [v2] arm64: fix unreachable code issue with cmpxchg Arnd Bergmann
2019-09-17 20:34 ` Nathan Chancellor
2019-09-18  9:02   ` Will Deacon
2019-09-18 16:02     ` Nathan Chancellor

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