// SPDX-License-Identifier: GPL-2.0 #include <linux/types.h> #include "../../../util/tsc.h" u64 rdtsc(void) { u64 val; /* * According to ARM DDI 0487F.c, from Armv8.0 to Armv8.5 inclusive, the * system counter is at least 56 bits wide; from Armv8.6, the counter * must be 64 bits wide. So the system counter could be less than 64 * bits wide and it is attributed with the flag 'cap_user_time_short' * is true. */ asm volatile("mrs %0, cntvct_el0" : "=r" (val)); return val; }