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/*
* x86 TSC related functions
*/
#ifndef _ASM_X86_TSC_H
#define _ASM_X86_TSC_H
#include <asm/processor.h>
#define NS_SCALE 10 /* 2^10, carefully chosen */
#define US_SCALE 32 /* 2^32, arbitralrily chosen */
/*
* 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, edx;
/*
* 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,
ASM_OUTPUT2("=a" (eax), "=d" (edx)),
"a" (0U), "d" (0U) : "ecx", "memory");
ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
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");
return 0;
}
static __always_inline cycles_t get_cycles_sync(void)
{
unsigned long long ret;
ret = __get_cycles_sync();
if (!ret)
rdtscll(ret);
return ret;
}
#ifdef CONFIG_PARAVIRT
/*
* For paravirt guests, some functionalities are executed through function
* pointers in the various pvops structures.
* These function pointers exist inside the kernel and can not
* be accessed by user space. To avoid this, we make a copy of the
* get_cycles_sync (called in kernel) but force the use of native_read_tsc.
* Ideally, the guest should set up it's own clock and vread
*/
static __always_inline long long vget_cycles_sync(void)
{
unsigned long long ret;
ret = __get_cycles_sync();
if (!ret)
ret = native_read_tsc();
return ret;
}
#else
# define vget_cycles_sync() get_cycles_sync()
#endif
extern void tsc_init(void);
extern void mark_tsc_unstable(char *reason);
extern int unsynchronized_tsc(void);
extern void init_tsc_clocksource(void);
int check_tsc_unstable(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);
extern void tsc_calibrate(void);
extern int notsc_setup(char *);
#endif
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