path: root/arch/s390/kernel/smp.c

/*
 *  SMP related functions
 *
 *    Copyright IBM Corp. 1999, 2012
 *    Author(s): Denis Joseph Barrow,
 *		 Martin Schwidefsky <schwidefsky@de.ibm.com>,
 *		 Heiko Carstens <heiko.carstens@de.ibm.com>,
 *
 *  based on other smp stuff by
 *    (c) 1995 Alan Cox, CymruNET Ltd  <alan@cymru.net>
 *    (c) 1998 Ingo Molnar
 *
 * The code outside of smp.c uses logical cpu numbers, only smp.c does
 * the translation of logical to physical cpu ids. All new code that
 * operates on physical cpu numbers needs to go into smp.c.
 */

#define KMSG_COMPONENT "cpu"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/kernel_stat.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/irqflags.h>
#include <linux/cpu.h>
#include <linux/slab.h>
#include <linux/crash_dump.h>
#include <asm/asm-offsets.h>
#include <asm/switch_to.h>
#include <asm/facility.h>
#include <asm/ipl.h>
#include <asm/setup.h>
#include <asm/irq.h>
#include <asm/tlbflush.h>
#include <asm/vtimer.h>
#include <asm/lowcore.h>
#include <asm/sclp.h>
#include <asm/vdso.h>
#include <asm/debug.h>
#include <asm/os_info.h>
#include <asm/sigp.h>
#include "entry.h"

enum {
	ec_schedule = 0,
	ec_call_function,
	ec_call_function_single,
	ec_stop_cpu,
};

enum {
	CPU_STATE_STANDBY,
	CPU_STATE_CONFIGURED,
};

struct pcpu {
	struct cpu cpu;
	struct _lowcore *lowcore;	/* lowcore page(s) for the cpu */
	unsigned long async_stack;	/* async stack for the cpu */
	unsigned long panic_stack;	/* panic stack for the cpu */
	unsigned long ec_mask;		/* bit mask for ec_xxx functions */
	int state;			/* physical cpu state */
	int polarization;		/* physical polarization */
	u16 address;			/* physical cpu address */
};

static u8 boot_cpu_type;
static u16 boot_cpu_address;
static struct pcpu pcpu_devices[NR_CPUS];

/*
 * The smp_cpu_state_mutex must be held when changing the state or polarization
 * member of a pcpu data structure within the pcpu_devices arreay.
 */
DEFINE_MUTEX(smp_cpu_state_mutex);

/*
 * Signal processor helper functions.
 */
static inline int __pcpu_sigp(u16 addr, u8 order, u32 parm, u32 *status)
{
	register unsigned int reg1 asm ("1") = parm;
	int cc;

	asm volatile(
		"	sigp	%1,%2,0(%3)\n"
		"	ipm	%0\n"
		"	srl	%0,28\n"
		: "=d" (cc), "+d" (reg1) : "d" (addr), "a" (order) : "cc");
	if (status && cc == 1)
		*status = reg1;
	return cc;
}

static inline int __pcpu_sigp_relax(u16 addr, u8 order, u32 parm, u32 *status)
{
	int cc;

	while (1) {
		cc = __pcpu_sigp(addr, order, parm, NULL);
		if (cc != SIGP_CC_BUSY)
			return cc;
		cpu_relax();
	}
}

static int pcpu_sigp_retry(struct pcpu *pcpu, u8 order, u32 parm)
{
	int cc, retry;

	for (retry = 0; ; retry++) {
		cc = __pcpu_sigp(pcpu->address, order, parm, NULL);
		if (cc != SIGP_CC_BUSY)
			break;
		if (retry >= 3)
			udelay(10);
	}
	return cc;
}

static inline int pcpu_stopped(struct pcpu *pcpu)
{
	u32 uninitialized_var(status);

	if (__pcpu_sigp(pcpu->address, SIGP_SENSE,
			0, &status) != SIGP_CC_STATUS_STORED)
		return 0;
	return !!(status & (SIGP_STATUS_CHECK_STOP|SIGP_STATUS_STOPPED));
}

static inline int pcpu_running(struct pcpu *pcpu)
{
	if (__pcpu_sigp(pcpu->address, SIGP_SENSE_RUNNING,
			0, NULL) != SIGP_CC_STATUS_STORED)
		return 1;
	/* Status stored condition code is equivalent to cpu not running. */
	return 0;
}

/*
 * Find struct pcpu by cpu address.
 */
static struct pcpu *pcpu_find_address(const struct cpumask *mask, int address)
{
	int