arch/xtensa/include/asm/cmpxchg.h

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

File Facts

System
Linux kernel
Corpus path
arch/xtensa/include/asm/cmpxchg.h
Extension
.h
Size
5775 bytes
Lines
226
Domain
Architecture Layer
Bucket
arch/xtensa
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 _XTENSA_CMPXCHG_H
#define _XTENSA_CMPXCHG_H

#ifndef __ASSEMBLER__

#include <linux/bits.h>
#include <linux/stringify.h>
#include <linux/cmpxchg-emu.h>

/*
 * cmpxchg
 */

static inline unsigned long
__cmpxchg_u32(volatile int *p, int old, int new)
{
#if XCHAL_HAVE_EXCLUSIVE
	unsigned long tmp, result;

	__asm__ __volatile__(
			"1:     l32ex   %[result], %[addr]\n"
			"       bne     %[result], %[cmp], 2f\n"
			"       mov     %[tmp], %[new]\n"
			"       s32ex   %[tmp], %[addr]\n"
			"       getex   %[tmp]\n"
			"       beqz    %[tmp], 1b\n"
			"2:\n"
			: [result] "=&a" (result), [tmp] "=&a" (tmp)
			: [new] "a" (new), [addr] "a" (p), [cmp] "a" (old)
			: "memory"
			);

	return result;
#elif XCHAL_HAVE_S32C1I
	__asm__ __volatile__(
			"       wsr     %[cmp], scompare1\n"
			"       s32c1i  %[new], %[mem]\n"
			: [new] "+a" (new), [mem] "+m" (*p)
			: [cmp] "a" (old)
			: "memory"
			);

	return new;
#else
	__asm__ __volatile__(
			"       rsil    a14, "__stringify(TOPLEVEL)"\n"
			"       l32i    %[old], %[mem]\n"
			"       bne     %[old], %[cmp], 1f\n"
			"       s32i    %[new], %[mem]\n"
			"1:\n"
			"       wsr     a14, ps\n"
			"       rsync\n"
			: [old] "=&a" (old), [mem] "+m" (*p)
			: [cmp] "a" (old), [new] "r" (new)
			: "a14", "memory");
	return old;
#endif
}
/* This function doesn't exist, so you'll get a linker error
 * if something tries to do an invalid cmpxchg(). */

extern void __cmpxchg_called_with_bad_pointer(void);

static __inline__ unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
{
	switch (size) {
	case 1:  return cmpxchg_emu_u8(ptr, old, new);
	case 4:  return __cmpxchg_u32(ptr, old, new);
	default: __cmpxchg_called_with_bad_pointer();
		 return 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) {
	case 4:
		return __cmpxchg_u32(ptr, old, new);

Annotation

Implementation Notes