root/arch/x86/vdso/vgetcpu.c

DEFINITIONS

1. __vdso_getcpu

/*
 * Copyright 2006 Andi Kleen, SUSE Labs.
 * Subject to the GNU Public License, v.2
 *
 * Fast user context implementation of getcpu()
 */

#include <linux/kernel.h>
#include <linux/getcpu.h>
#include <linux/jiffies.h>
#include <linux/time.h>
#include <asm/vsyscall.h>
#include <asm/vgtod.h>
#include "vextern.h"

notrace long
__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
{
        unsigned int p;

        if (*vdso_vgetcpu_mode == VGETCPU_RDTSCP) {
                /* Load per CPU data from RDTSCP */
                native_read_tscp(&p);
        } else {
                /* Load per CPU data from GDT */
                asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
        }
        if (cpu)
                *cpu = p & 0xfff;
        if (node)
                *node = p >> 12;
        return 0;
}

long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
        __attribute__((weak, alias("__vdso_getcpu")));