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