/* * linux/include/asm-i386/tsc.h * * i386 TSC related functions */ #ifndef _ASM_i386_TSC_H #define _ASM_i386_TSC_H #include <asm/processor.h> /* * Standard way to access the cycle counter. */ typedef unsigned long long cycles_t; extern unsigned int cpu_khz; extern unsigned int tsc_khz; static inline cycles_t get_cycles(void) { unsigned long long ret = 0; #ifndef CONFIG_X86_TSC if (!cpu_has_tsc) return 0; #endif #if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC) rdtscll(ret); #endif return ret; } /* Like get_cycles, but make sure the CPU is synchronized. */ static __always_inline cycles_t get_cycles_sync(void) { unsigned long long ret; unsigned eax; /* * Use RDTSCP if possible; it is guaranteed to be synchronous * and doesn't cause a VMEXIT on Hypervisors */ alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP, "=A" (ret), "0" (0ULL) : "ecx", "memory"); if (ret) return ret; /* * Don't do an additional sync on CPUs where we know * RDTSC is already synchronous: */ alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC, "=a" (eax), "0" (1) : "ebx","ecx","edx","memory"); rdtscll(ret); return ret; } extern void tsc_init(void); extern void mark_tsc_unstable(char *reason); extern int unsynchronized_tsc(void); extern void init_tsc_clocksource(void); /* * Boot-time check whether the TSCs are synchronized across * all CPUs/cores: */ extern void check_tsc_sync_source(int cpu); extern void check_tsc_sync_target(void); #endif