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Diffstat (limited to 'include/asm-i386/cmpxchg.h')
| -rw-r--r-- | include/asm-i386/cmpxchg.h | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/include/asm-i386/cmpxchg.h b/include/asm-i386/cmpxchg.h new file mode 100644 index 00000000000..7adcef0cd53 --- /dev/null +++ b/include/asm-i386/cmpxchg.h @@ -0,0 +1,293 @@ +#ifndef __ASM_CMPXCHG_H +#define __ASM_CMPXCHG_H + +#include <linux/bitops.h> /* for LOCK_PREFIX */ + +#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)) + + +#ifdef CONFIG_X86_CMPXCHG64 + +/* + * 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 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)>>32ULL)); +} +#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)>>32ULL) ) : \ + __set_64bit(ptr, ll_low(value), ll_high(value)) ) + +#endif + +/* + * 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 + +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; +} + +#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 = __cmpxchg((ptr), (unsigned long)(o), \ + (unsigned long)(n), sizeof(*(ptr))); \ + else \ + __ret = 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 = __cmpxchg_local((ptr), (unsigned long)(o), \ + (unsigned long)(n), sizeof(*(ptr))); \ + else \ + __ret = cmpxchg_386((ptr), (unsigned long)(o), \ + (unsigned long)(n), sizeof(*(ptr))); \ + __ret; \ +}) +#endif + +#ifdef CONFIG_X86_CMPXCHG64 + +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; +} + +#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 + +#endif |