[deliverable/linux.git] / arch / x86 / vdso / vgetcpu.c

/*
 * 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")));
Commit	Line	Data
2aae950b AK	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	#include "vextern.h"
	15
23adec55 SR	16	notrace long
23adec55 SR	17	__vdso_getcpu(unsigned cpu, unsigned node, struct getcpu_cache *unused)
2aae950b	18	{
8f12dea6	19	unsigned int p;
2aae950b	20
4307d1e5	21	if (*vdso_vgetcpu_mode == VGETCPU_RDTSCP) {
2aae950b	22	/* Load per CPU data from RDTSCP */
8f12dea6	23	native_read_tscp(&p);
2aae950b AK	24	} else {
	25	/* Load per CPU data from GDT */
	26	asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
	27	}
2aae950b AK	28	if (cpu)
	29	*cpu = p & 0xfff;
	30	if (node)
	31	*node = p >> 12;
	32	return 0;
	33	}
	34
	35	long getcpu(unsigned cpu, unsigned node, struct getcpu_cache *tcache)
	36	__attribute__((weak, alias("__vdso_getcpu")));