arch/parisc/include/asm/cmpxchg.h

Source file repositories/reference/linux-study-clean/arch/parisc/include/asm/cmpxchg.h

File Facts

System
Linux kernel
Corpus path
arch/parisc/include/asm/cmpxchg.h
Extension
.h
Size
3757 bytes
Lines
123
Domain
Architecture Layer
Bucket
arch/parisc
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 _ASM_PARISC_CMPXCHG_H_
#define _ASM_PARISC_CMPXCHG_H_

/* This should get optimized out since it's never called.
** Or get a link error if xchg is used "wrong".
*/
extern void __xchg_called_with_bad_pointer(void);

/* __xchg32/64 defined in arch/parisc/lib/bitops.c */
extern unsigned long __xchg8(char, volatile char *);
extern unsigned long __xchg32(int, volatile int *);
#ifdef CONFIG_64BIT
extern unsigned long __xchg64(unsigned long, volatile unsigned long *);
#endif

/* optimizer better get rid of switch since size is a constant */
static inline unsigned long
__arch_xchg(unsigned long x, volatile void *ptr, int size)
{
	switch (size) {
#ifdef CONFIG_64BIT
	case 8: return __xchg64(x, (volatile unsigned long *) ptr);
#endif
	case 4: return __xchg32((int) x, (volatile int *) ptr);
	case 1: return __xchg8((char) x, (volatile char *) ptr);
	}
	__xchg_called_with_bad_pointer();
	return x;
}

/*
** REVISIT - Abandoned use of LDCW in xchg() for now:
** o need to test sizeof(*ptr) to avoid clearing adjacent bytes
** o and while we are at it, could CONFIG_64BIT code use LDCD too?
**
**	if (__builtin_constant_p(x) && (x == NULL))
**		if (((unsigned long)p & 0xf) == 0)
**			return __ldcw(p);
*/
#define arch_xchg(ptr, x)						\
({									\
	__typeof__(*(ptr)) __ret;					\
	__typeof__(*(ptr)) _x_ = (x);					\
	__ret = (__typeof__(*(ptr)))					\
		__arch_xchg((unsigned long)_x_, (ptr), sizeof(*(ptr)));	\
	__ret;								\
})

/* bug catcher for when unsupported size is used - won't link */
extern void __cmpxchg_called_with_bad_pointer(void);

/* __cmpxchg_u... defined in arch/parisc/lib/bitops.c */
extern u8 __cmpxchg_u8(volatile u8 *ptr, u8 old, u8 new_);
extern u16 __cmpxchg_u16(volatile u16 *ptr, u16 old, u16 new_);
extern u32 __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
extern u64 __cmpxchg_u64(volatile u64 *ptr, u64 old, u64 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
#ifdef CONFIG_64BIT
		size == 8 ? __cmpxchg_u64(ptr, old, new_) :
#endif
		size == 4 ? __cmpxchg_u32(ptr, old, new_) :
		size == 2 ? __cmpxchg_u16(ptr, old, new_) :
		size == 1 ? __cmpxchg_u8(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))); \
})

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

static inline unsigned long __cmpxchg_local(volatile void *ptr,
				      unsigned long old,
				      unsigned long new_, int size)
{
	switch (size) {
#ifdef CONFIG_64BIT
	case 8:	return __cmpxchg_u64((u64 *)ptr, old, new_);
#endif
	case 4:	return __cmpxchg_u32(ptr, old, new_);

Annotation

Implementation Notes