22 lines
498 B
C
22 lines
498 B
C
// 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;
|
|
}
|