arch/sparc/include/asm/cmpxchg_32.h

Source file repositories/reference/linux-study-clean/arch/sparc/include/asm/cmpxchg_32.h

File Facts

System
Linux kernel
Corpus path
arch/sparc/include/asm/cmpxchg_32.h
Extension
.h
Size
2585 bytes
Lines
79
Domain
Architecture Layer
Bucket
arch/sparc
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __ARCH_SPARC_CMPXCHG__
#define __ARCH_SPARC_CMPXCHG__

unsigned long __xchg_u32(volatile u32 *m, u32 new);
void __xchg_called_with_bad_pointer(void);

static __always_inline unsigned long __arch_xchg(unsigned long x, __volatile__ void * ptr, int size)
{
	switch (size) {
	case 4:
		return __xchg_u32(ptr, x);
	}
	__xchg_called_with_bad_pointer();
	return x;
}

#define arch_xchg(ptr,x) ({(__typeof__(*(ptr)))__arch_xchg((unsigned long)(x),(ptr),sizeof(*(ptr)));})

/* Emulate cmpxchg() the same way we emulate atomics,
 * by hashing the object address and indexing into an array
 * of spinlocks to get a bit of performance...
 *
 * See arch/sparc/lib/atomic32.c for implementation.
 *
 * Cribbed from <asm-parisc/atomic.h>
 */

/* bug catcher for when unsupported size is used - won't link */
void __cmpxchg_called_with_bad_pointer(void);
u8 __cmpxchg_u8(volatile u8 *m, u8 old, u8 new_);
u16 __cmpxchg_u16(volatile u16 *m, u16 old, u16 new_);
u32 __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);

/* don't worry...optimizer will get rid of most of this */
static inline unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
{
	return
		size == 1 ? __cmpxchg_u8(ptr, old, new_) :
		size == 2 ? __cmpxchg_u16(ptr, old, new_) :
		size == 4 ? __cmpxchg_u32(ptr, old, new_) :
			(__cmpxchg_called_with_bad_pointer(), old);
}

#define arch_cmpxchg(ptr, o, n)						\
({									\
	__typeof__(*(ptr)) _o_ = (o);					\
	__typeof__(*(ptr)) _n_ = (n);					\
	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	\
			(unsigned long)_n_, sizeof(*(ptr)));		\
})

u64 __cmpxchg_u64(volatile u64 *ptr, u64 old, u64 new);
#define arch_cmpxchg64(ptr, old, new)	__cmpxchg_u64(ptr, old, new)

#include <asm-generic/cmpxchg-local.h>

/*
 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
 * them available.
 */
#define arch_cmpxchg_local(ptr, o, n)				  	       \
	((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o),\
			(unsigned long)(n), sizeof(*(ptr))))
#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))

#endif /* __ARCH_SPARC_CMPXCHG__ */

Annotation

Implementation Notes