diff options
| -rw-r--r-- | arch/i386/kernel/cpu/intel.c | 48 | ||||
| -rw-r--r-- | include/asm-i386/system.h | 42 |
2 files changed, 87 insertions, 3 deletions
diff --git a/arch/i386/kernel/cpu/intel.c b/arch/i386/kernel/cpu/intel.c index 43601de0f63..c28d26fb5f2 100644 --- a/arch/i386/kernel/cpu/intel.c +++ b/arch/i386/kernel/cpu/intel.c @@ -6,6 +6,7 @@ #include <linux/bitops.h> #include <linux/smp.h> #include <linux/thread_info.h> +#include <linux/module.h> #include <asm/processor.h> #include <asm/msr.h> @@ -264,5 +265,52 @@ __init int intel_cpu_init(void) return 0; } +#ifndef CONFIG_X86_CMPXCHG +unsigned long cmpxchg_386_u8(volatile void *ptr, u8 old, u8 new) +{ + u8 prev; + unsigned long flags; + + /* Poor man's cmpxchg for 386. Unsuitable for SMP */ + local_irq_save(flags); + prev = *(u8 *)ptr; + if (prev == old) + *(u8 *)ptr = new; + local_irq_restore(flags); + return prev; +} +EXPORT_SYMBOL(cmpxchg_386_u8); + +unsigned long cmpxchg_386_u16(volatile void *ptr, u16 old, u16 new) +{ + u16 prev; + unsigned long flags; + + /* Poor man's cmpxchg for 386. Unsuitable for SMP */ + local_irq_save(flags); + prev = *(u16 *)ptr; + if (prev == old) + *(u16 *)ptr = new; + local_irq_restore(flags); + return prev; +} +EXPORT_SYMBOL(cmpxchg_386_u16); + +unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new) +{ + u32 prev; + unsigned long flags; + + /* Poor man's cmpxchg for 386. Unsuitable for SMP */ + local_irq_save(flags); + prev = *(u32 *)ptr; + if (prev == old) + *(u32 *)ptr = new; + local_irq_restore(flags); + return prev; +} +EXPORT_SYMBOL(cmpxchg_386_u32); +#endif + // arch_initcall(intel_cpu_init); diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h index 97d52ac49e4..772f85da120 100644 --- a/include/asm-i386/system.h +++ b/include/asm-i386/system.h @@ -263,6 +263,10 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz #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)))) +#endif static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size) @@ -291,10 +295,42 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, return old; } -#define cmpxchg(ptr,o,n)\ - ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\ - (unsigned long)(n),sizeof(*(ptr)))) +#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; \ +}) #endif #ifdef CONFIG_X86_CMPXCHG64 |