diff options
Diffstat (limited to 'arch/x86/include/asm/msr.h')
| -rw-r--r-- | arch/x86/include/asm/msr.h | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index c89ed6ceed02..ff0c120dafe5 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -109,7 +109,16 @@ notrace static inline int native_write_msr_safe(unsigned int msr, extern int rdmsr_safe_regs(u32 regs[8]); extern int wrmsr_safe_regs(u32 regs[8]); -static __always_inline unsigned long long native_read_tsc(void) +/** + * rdtsc() - returns the current TSC without ordering constraints + * + * rdtsc() returns the result of RDTSC as a 64-bit integer. The + * only ordering constraint it supplies is the ordering implied by + * "asm volatile": it will put the RDTSC in the place you expect. The + * CPU can and will speculatively execute that RDTSC, though, so the + * results can be non-monotonic if compared on different CPUs. + */ +static __always_inline unsigned long long rdtsc(void) { DECLARE_ARGS(val, low, high); |