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Commit b08ee5f7 authored by Borislav Petkov's avatar Borislav Petkov Committed by H. Peter Anvin
Browse files

x86: Simplify __HAVE_ARCH_CMPXCHG tests 



Both the 32-bit and 64-bit cmpxchg.h header define __HAVE_ARCH_CMPXCHG
and there's ifdeffery which checks it. But since both bitness define it,
we can just as well move it up to the main cmpxchg header and simpify a
bit of code in doing that.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20140711104338.GB17083@pd.tnic


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 89171579

arch/x86/include/asm/cmpxchg.h

+2 −2
Original line number Diff line number Diff line
@@ -4,6 +4,8 @@ 
#include <linux/compiler.h>

#include <asm/alternative.h> /* Provides LOCK_PREFIX */



#define __HAVE_ARCH_CMPXCHG 1



/*

 * Non-existant functions to indicate usage errors at link time

 * (or compile-time if the compiler implements __compiletime_error().
@@ -143,7 +145,6 @@ extern void __add_wrong_size(void) 
# include <asm/cmpxchg_64.h>

#endif



#ifdef __HAVE_ARCH_CMPXCHG

#define cmpxchg(ptr, old, new)						\

	__cmpxchg(ptr, old, new, sizeof(*(ptr)))
@@ -152,7 +153,6 @@ extern void __add_wrong_size(void) 


#define cmpxchg_local(ptr, old, new)					\

	__cmpxchg_local(ptr, old, new, sizeof(*(ptr)))

#endif



/*

 * xadd() adds "inc" to "*ptr" and atomically returns the previous

arch/x86/include/asm/cmpxchg_32.h

+0 −2
Original line number Diff line number Diff line
@@ -34,8 +34,6 @@ static inline void set_64bit(volatile u64 *ptr, u64 value) 
		     : "memory");

}



#define __HAVE_ARCH_CMPXCHG 1



#ifdef CONFIG_X86_CMPXCHG64

#define cmpxchg64(ptr, o, n)						\

	((__typeof__(*(ptr)))__cmpxchg64((ptr), (unsigned long long)(o), \

arch/x86/include/asm/cmpxchg_64.h

+0 −2
Original line number Diff line number Diff line
@@ -6,8 +6,6 @@ static inline void set_64bit(volatile u64 *ptr, u64 val) 
	*ptr = val;

}



#define __HAVE_ARCH_CMPXCHG 1



#define cmpxchg64(ptr, o, n)						\

({									\

	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\

arch/x86/include/asm/mc146818rtc.h

+1 −1
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ 
#define RTC_ALWAYS_BCD	1	/* RTC operates in binary mode */

#endif



#if defined(CONFIG_X86_32) && defined(__HAVE_ARCH_CMPXCHG)

#if defined(CONFIG_X86_32)

/*

 * This lock provides nmi access to the CMOS/RTC registers.  It has some

 * special properties.  It is owned by a CPU and stores the index register

arch/x86/include/asm/mutex_32.h

+2 −14
Original line number Diff line number Diff line
@@ -100,23 +100,11 @@ do { \ 
static inline int __mutex_fastpath_trylock(atomic_t *count,

					   int (*fail_fn)(atomic_t *))

{

	/*

	 * We have two variants here. The cmpxchg based one is the best one

	 * because it never induce a false contention state.  It is included

	 * here because architectures using the inc/dec algorithms over the

	 * xchg ones are much more likely to support cmpxchg natively.

	 *

	 * If not we fall back to the spinlock based variant - that is

	 * just as efficient (and simpler) as a 'destructive' probing of

	 * the mutex state would be.

	 */

#ifdef __HAVE_ARCH_CMPXCHG

	/* cmpxchg because it never induces a false contention state. */

	if (likely(atomic_cmpxchg(count, 1, 0) == 1))

		return 1;



	return 0;

#else

	return fail_fn(count);

#endif

}



#endif /* _ASM_X86_MUTEX_32_H */