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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: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20140711104338.GB17083@pd.tnic
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Borislav Petkov 2014-07-11 12:43:38 +02:00 committed by H. Peter Anvin
parent 891715793f
commit b08ee5f7e4
6 changed files with 5 additions and 25 deletions
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4
arch/x86/include/asm/cmpxchg.h
View File

@ -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

2
arch/x86/include/asm/cmpxchg_32.h
View File

@ -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), \

2
arch/x86/include/asm/cmpxchg_64.h
View File

@ -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); \

2
arch/x86/include/asm/mc146818rtc.h
View File

@ -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

16
arch/x86/include/asm/mutex_32.h
View File

@ -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 */

4
arch/x86/kernel/acpi/boot.c
View File

@ -74,10 +74,6 @@ int acpi_fix_pin2_polarity __initdata;
static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
#endif
#ifndef __HAVE_ARCH_CMPXCHG
#warning ACPI uses CMPXCHG, i486 and later hardware
#endif
/* --------------------------------------------------------------------------
Boot-time Configuration
-------------------------------------------------------------------------- */