#ifndef __ASM_CMPXCHG_H
#define __ASM_CMPXCHG_H
#include <linux/bitops.h> /* for LOCK_PREFIX */
/*
* Note: if you use set64_bit(), __cmpxchg64(), or their variants, you
* you need to test for the feature in boot_cpu_data.
*/
#define xchg(ptr, v) \
((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), sizeof(*(ptr))))
struct __xchg_dummy {
unsigned long a[100];
};
#define __xg(x) ((struct __xchg_dummy *)(x))
/*
* The semantics of XCHGCMP8B are a bit strange, this is why
* there is a loop and the loading of %%eax and %%edx has to
* be inside. This inlines well in most cases, the cached
* cost is around ~38 cycles. (in the future we might want
* to do an SIMD/3DNOW!/MMX/FPU 64-bit store here, but that
* might have an implicit FPU-save as a cost, so it's not
* clear which path to go.)
*
* cmpxchg8b must be used with the lock prefix here to allow
* the instruction to be executed atomically, see page 3-102
* of the instruction set reference 24319102.pdf. We need
* the reader side to see the coherent 64bit value.
*/
static inline void __set_64bit(unsigned long long *ptr,
unsigned int low, unsigned int high)
{
asm volatile("\n1:\t"
"movl (%0), %%eax\n\t"
"movl 4(%0), %%edx\n\t"
LOCK_PREFIX "cmpxchg8b (%0)\n\t"
"jnz 1b"
: /* no outputs */
: "D"(ptr),
"b"(low),
"c"(high)
: "ax", "dx", "memory");
}
static inline void __set_64bit_constant(unsigned long long *ptr,
unsigned long long value)
{
__set_64bit(ptr, (unsigned int)value, (unsigned int)(value >> 32));
}
#define ll_low(x) *(((unsigned int *)&(x)) + 0)
#define ll_high(x) *(((unsigned int *)&(x)) + 1)
static inline void __set_64bit_var(unsigned long long *ptr,
unsigned long long value)
{
__set_64bit(ptr, ll_low(value), ll_high(value));
}
#define set_64bit(ptr, value) \
(__builtin_constant_p((value)) \
? __set_64bit_constant((ptr), (value)) \
: __set_64bit_var((ptr), (value)))
#define _set_64bit(ptr, value) \
(__builtin_constant_p(value) \
? __set_64bit(ptr, (unsigned int)(value), \
(unsigned int)((value) >> 32)) \
: __set_64bit(ptr, ll_low((value)), ll_high((value))))
/*
* Note: no "lock" prefix even on SMP: xchg always implies lock anyway
* Note 2: xchg has side effect, so that attribute volatile is necessary,
* but generally the primitive is invalid, *ptr is output argument. --ANK
*/
static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
int size)
{
switch (size) {
case 1:
asm volatile("xchgb %b0,%1"
: "=q" (x)
: "m" (*__xg(ptr)), "0" (x)
: "memory");
break;
case 2:
asm volatile("xchgw %w0,%1"
: "=r" (x)
: "m" (*__xg(ptr)), "0" (x)
: "memory");
break;
case 4:
asm volatile("xchgl %0,%1"
: "=r" (x)
: "m" (*__xg(ptr)), "0" (x)
: "memory");
break;
}
return x;
}
/*
* Atomic compare and exchange. Compare OLD with MEM, if identical,
* store NEW in MEM. Return the initial value in MEM. Success is
* indicated by comparing RETURN with OLD.
*/
#ifdef CONFIG_X86_CMPXCHG
#define __HAVE_ARCH_CMPXCHG 1
#define cmpxchg(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))))
#define sync_cmpxchg(ptr, o, n) \
((__typeof__(*(ptr)))__sync_cmpxchg((ptr), (unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))))
#define cmpxchg_local(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))))
#endif
#ifdef CONFIG_X86_CMPXCHG64
#define cmpxchg64(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg64((ptr), (unsigned long long)(o), \
(unsigned long long)(n)))
#define cmpxchg64_local(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg64_local((ptr), (unsigned long long)(o), \
(unsigned long long)(n)))
#endif
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
unsigned long new, int size)
{
unsigned long prev;
switch (size) {
case 1:
asm volatile(LOCK_PREFIX "cmpxchgb %b1,%2"
: "=a"(prev)
: "q"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
case 2:
asm volatile(LOCK_PREFIX "cmpxchgw %w1,%2"
: "=a"(prev)
: "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
case 4:
asm volatile(LOCK_PREFIX "cmpxchgl %1,%2"
: "=a"(prev)
: "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
}
return old;
}
/*
* Always use locked operations when touching memory shared with a
* hypervisor, since the system may be SMP even if the guest kernel
* isn't.
*/
static inline unsigned long __sync_cmpxchg(volatile void *ptr,
unsigned long old,
unsigned long new, int size)
{
unsigned long prev;
switch (size) {
case 1:
asm volatile("lock; cmpxchgb %b1,%2"
: "=a"(prev)
: "q"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
case 2:
asm volatile("lock; cmpxchgw %w1,%2"
: "=a"(prev)
: "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
case 4:
asm volatile("lock; cmpxchgl %1,%2"
: "=a"(prev)
: "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
}
return old;
}
static inline unsigned long __cmpxchg_local(volatile void *ptr,
unsigned long old,
unsigned long new, int size)
{
unsigned long prev;
switch (size) {
case 1:
asm volatile("cmpxchgb %b1,%2"
: "=a"(prev)
: "q"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
case 2:
asm volatile("cmpxchgw %w1,%2"
: "=a"(prev)
: "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
case 4:
asm volatile("cmpxchgl %1,%2"
: "=a"(prev)
: "r"(new), "m"(*__xg(ptr)), "0"(old)
: "memory");
return prev;
}
return old;
}
static inline unsigned long long __cmpxchg64(volatile void *ptr,
unsigned long long old,
unsigned long long new)
{
unsigned long long prev;
asm volatile(LOCK_PREFIX "cmpxchg8b %3"
: "=A"(prev)
: "b"((unsigned long)new),
"c"((unsigned long)(new >> 32)),
"m"(*__xg(ptr)),
"0"(old)
: "memory");
return prev;
}
static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
unsigned long long old,
unsigned long long new)
{
unsigned long long prev;
asm volatile("cmpxchg8b %3"
: "=A"(prev)
: "b"((unsigned long)new),
"c"((unsigned long)(new >> 32)),
"m"(*__xg(ptr)),
"0"(old)
: "memory");
return prev;
}
#ifndef CONFIG_X86_CMPXCHG
/*
* Building a kernel capable running on 80386. It may be necessary to
* simulate the cmpxchg on the 80386 CPU. For that purpose we define
* a function for each of the sizes we support.
*/
extern unsigned long cmpxchg_386_u8(volatile void *, u8, u8);
extern unsigned long cmpxchg_386_u16(volatile void *, u16, u16);
extern unsigned long cmpxchg_386_u32(volatile void *, u32, u32);
static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
unsigned long new, int size)
{
switch (size) {
case 1:
return cmpxchg_386_u8(ptr, old, new);
case 2:
return cmpxchg_386_u16(ptr, old, new);
case 4:
return cmpxchg_386_u32(ptr, old, new);
}
return old;
}
#define cmpxchg(ptr, o, n) \
({ \
__typeof__(*(ptr)) __ret; \
if (likely(boot_cpu_data.x86 > 3)) \
__ret = (__typeof__(*(ptr)))__cmpxchg((ptr), \
(unsigned long)(o), (unsigned long)(n), \
sizeof(*(ptr))); \
else \
__ret = (__typeof__(*(ptr)))cmpxchg_386((ptr), \
(unsigned long)(o), (unsigned long)(n), \
sizeof(*(ptr))); \
__ret; \
})
#define cmpxchg_local(ptr, o, n) \
({ \
__typeof__(*(ptr)) __ret; \
if (likely(boot_cpu_data.x86 > 3)) \
__ret = (__typeof__(*(ptr)))__cmpxchg_local((ptr), \
(unsigned long)(o), (unsigned long)(n), \
sizeof(*(ptr))); \
else \
__ret = (__typeof__(*(ptr)))cmpxchg_386((ptr), \
(unsigned long)(o), (unsigned long)(n), \
sizeof(*(ptr))); \
__ret; \
})
#endif
#ifndef CONFIG_X86_CMPXCHG64
/*
* Building a kernel capable running on 80386 and 80486. It may be necessary
* to simulate the cmpxchg8b on the 80386 and 80486 CPU.
*/
extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
#define cmpxchg64(ptr, o, n) \
({ \
__typeof__(*(ptr)) __ret; \
if (likely(boot_cpu_data.x86 > 4)) \
__ret = (__typeof__(*(ptr)))__cmpxchg64((ptr), \
(unsigned long long)(o), \
(unsigned long long)(n)); \
else \
__ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr), \
(unsigned long long)(o), \
(unsigned long long)(n)); \
__ret; \
})
#define cmpxchg64_local(ptr, o, n) \
({ \
__typeof__(*(ptr)) __ret; \
if (likely(boot_cpu_data.x86 > 4)) \
__ret = (__typeof__(*(ptr)))__cmpxchg64_local((ptr), \
(unsigned long long)(o), \
(unsigned long long)(n)); \
else \
__ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr), \
(unsigned long long)(o), \
(unsigned long long)(n)); \
__ret; \
})
#endif
#endif
