1/*
 2 * Copyright 2006 Andi Kleen, SUSE Labs.
 3 * Subject to the GNU Public License, v.2
 4 *
 5 * Fast user context implementation of getcpu()
 6 */
 7
 8#include <linux/kernel.h>
 9#include <linux/getcpu.h>
10#include <linux/jiffies.h>
11#include <linux/time.h>
12#include <asm/vsyscall.h>
13#include <asm/vgtod.h>
14
15notrace long
16__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
17{
18	unsigned int p;
19
20	if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
21		/* Load per CPU data from RDTSCP */
22		native_read_tscp(&p);
23	} else {
24		/* Load per CPU data from GDT */
25		asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
26	}
27	if (cpu)
28		*cpu = p & 0xfff;
29	if (node)
30		*node = p >> 12;
31	return 0;
32}
33
34long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
35	__attribute__((weak, alias("__vdso_getcpu")));