diff options
Diffstat (limited to 'arch/x86/kernel/cpu')
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index cc8c501b9f3..867ff94579b 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -342,5 +342,22 @@ unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new) EXPORT_SYMBOL(cmpxchg_386_u32); #endif +#ifndef CONFIG_X86_CMPXCHG64 +unsigned long long cmpxchg_486_u64(volatile void *ptr, u64 old, u64 new) +{ + u64 prev; + unsigned long flags; + + /* Poor man's cmpxchg8b for 386 and 486. Unsuitable for SMP */ + local_irq_save(flags); + prev = *(u64 *)ptr; + if (prev == old) + *(u64 *)ptr = new; + local_irq_restore(flags); + return prev; +} +EXPORT_SYMBOL(cmpxchg_486_u64); +#endif + // arch_initcall(intel_cpu_init); |