vgetcpu.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Fast user context implementation of getcpu()
 4 */
 5
 6#include <asm/vdso.h>
 7#include <linux/getcpu.h>
 8
 9static __always_inline int read_cpu_id(void)
10{
11	int cpu_id;
12
13#ifdef CONFIG_64BIT
14	__asm__ __volatile__(
15	"	rdtime.d $zero, %0\n"
16	: "=r" (cpu_id)
17	:
18	: "memory");
19#else
20	__asm__ __volatile__(
21	"	rdtimel.w $zero, %0\n"
22	: "=r" (cpu_id)
23	:
24	: "memory");
25#endif
26
27	return cpu_id;
28}
29
30extern
31int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
32int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
33{
34	int cpu_id;
35
36	cpu_id = read_cpu_id();
37
38	if (cpu)
39		*cpu = cpu_id;
40
41	if (node)
42		*node = vdso_u_arch_data.pdata[cpu_id].node;
43
44	return 0;
45}