rdtsc_aarch64.c

#ifndef __aarch64__
#error Arches other than arm64 are not supported
#endif // #ifndef __aarch64__

#define FORCE_INLINE inline __attribute__((always_inline))

typedef unsigned long u64;

static FORCE_INLINE u64 rdtsc(void) {
  u64 val;
  // use isb to avoid speculative read of cntvct_el0
  __asm__ volatile("isb;\n\tmrs %0, cntvct_el0" : "=r" (val) :: "memory");
  return val;
}

static FORCE_INLINE u64 tsc_freq(void) {
  u64 val;
  __asm__ volatile("mrs %0, cntfrq_el0" : "=r" (val));
  return val;
}

static FORCE_INLINE u64 tsc_to_ns(u64 ticks) {
  return (ticks * 1000000000) / tsc_freq();
}