smp.c

linux-2.6.15.6

/*
 *  arch/s390/kernel/smp.c
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Denis Joseph Barrow ([e-mail],[e-mail]),
 *               Martin Schwidefsky ([e-mail])
 *               Heiko Carstens ([e-mail])
 *
 *  based on other smp stuff by 
 *    (c) 1995 Alan Cox, CymruNET Ltd  <[e-mail]>
 *    (c) 1998 Ingo Molnar
 *
 * We work with logical cpu numbering everywhere we can. The only
 * functions using the real cpu address (got from STAP) are the sigp
 * functions. For all other functions we use the identity mapping.
 * That means that cpu_number_map[i] == i for every cpu. cpu_number_map is
 * used e.g. to find the idle task belonging to a logical cpu. Every array
 * in the kernel is sorted by the logical cpu number and not by the physical
 * one which is causing all the confusion with __cpu_logical_map and
 * cpu_number_map in other architectures.
 */

#include <linux/module.h>
#include <linux/init.h>

#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/kernel_stat.h>
#include <linux/smp_lock.h>

#include <linux/delay.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
#include <linux/cpu.h>

#include <asm/sigp.h>
#include <asm/pgalloc.h>
#include <asm/irq.h>
#include <asm/s390_ext.h>
#include <asm/cpcmd.h>
#include <asm/tlbflush.h>

/* prototypes */

extern volatile int __cpu_logical_map[];

/*
 * An array with a pointer the lowcore of every CPU.
 */

struct _lowcore *lowcore_ptr[NR_CPUS];

cpumask_t cpu_online_map;
cpumask_t cpu_possible_map;

static struct task_struct *current_set[NR_CPUS];

EXPORT_SYMBOL(cpu_online_map);

/*
 * Reboot, halt and power_off routines for SMP.
 */
extern char vmhalt_cmd[];
extern char vmpoff_cmd[];

extern void reipl(unsigned long devno);
extern void reipl_diag(void);

static void smp_ext_bitcall(int, ec_bit_sig);
static void smp_ext_bitcall_others(ec_bit_sig);

/*
 * Structure and data for smp_call_function(). This is designed to minimise
 * static memory requirements. It also looks cleaner.
 */
static DEFINE_SPINLOCK(call_lock);

struct call_data_struct {
	void (*func) (void *info);
	void *info;
	atomic_t started;
	atomic_t finished;
	int wait;
};

static struct call_data_struct * call_data;

/*
 * 'Call function' interrupt callback
 */
static void do_call_function(void)
{
	void (*func) (void *info) = call_data->func;
	void *info = call_data->info;
	int wait = call_data->wait;

	atomic_inc(&call_data->started);
	(*func)(info);
	if (wait)
		atomic_inc(&call_data->finished);
}

/*
 * this function sends a 'generic call function' IPI to all other CPUs
 * in the system.
 */

int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
			int wait)
/*
 * [SUMMARY] Run a function on all other CPUs.
 * <func> The function to run. This must be fast and non-blocking.
 * <info> An arbitrary pointer to pass to the function.
 * <nonatomic> currently unused.
 * <wait> If true, wait (atomically) until function has completed on other CPUs.
 * [RETURNS] 0 on success, else a negative status code. Does not return until
 * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */
{
	struct call_data_struct data;
	int cpus = num_online_cpus()-1;

	if (cpus <= 0)
		return 0;

	/* Can deadlock when called with interrupts disabled */
	WARN_ON(irqs_disabled());

	data.func = func;
	data.info = info;
	atomic_set(&data.started, 0);
	data.wait = wait;
	if (wait)
		atomic_set(&data.finished, 0);

	spin_lock(&call_lock);
	call_data = &data;
	/* Send a message to all other CPUs and wait for them to respond */
        smp_ext_bitcall_others(ec_call_function);

	/* Wait for response */
	while (atomic_read(&data.started) != cpus)
		cpu_relax();

	if (wait)
		while (atomic_read(&data.finished) != cpus)
			cpu_relax();
	spin_unlock(&call_lock);

	return 0;
}

/*
 * Call a function on one CPU
 * cpu : the CPU the function should be executed on
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler. You may call it from a bottom half.
 *
 * It is guaranteed that the called function runs on the specified CPU,
 * preemption is disabled.
 */
int smp_call_function_on(void (*func) (void *info), void *info,
			 int nonatomic, int wait, int cpu)
{
	struct call_data_struct data;
	int curr_cpu;

	if (!cpu_online(cpu))
		return -EINVAL;

	/* disable preemption for local function call */
	curr_cpu = get_cpu();

	if (curr_cpu == cpu) {
		/* direct call to function */
		func(info);
		put_cpu();
		return 0;
	}

	data.func = func;
	data.info = info;
	atomic_set(&data.started, 0);
	data.wait = wait;
	if (wait)
		atomic_set(&data.finished, 0);

	spin_lock_bh(&call_lock);
	call_data = &data;
	smp_ext_bitcall(cpu, ec_call_function);

	/* Wait for response */
	while (atomic_read(&data.started) != 1)
		cpu_relax();

	if (wait)
		while (atomic_read(&data.finished) != 1)
			cpu_relax();

	spin_unlock_bh(&call_lock);
	put_cpu();
	return 0;
}
EXPORT_SYMBOL(smp_call_function_on);

static inline void do_send_stop(void)
{
        int cpu, rc;

        /* stop all processors */
	for_each_online_cpu(cpu) {
		if (cpu == smp_processor_id())
			continue;
		do {
			rc = signal_processor(cpu, sigp_stop);
		} while (rc == sigp_busy);
	}
}

static inline void do_store_status(void)
{
        int cpu, rc;

        /* store status of all processors in their lowcores (real 0) */
	for_each_online_cpu(cpu) {
		if (cpu == smp_processor_id())
			continue;
		do {
			rc = signal_processor_p(
				(__u32)(unsigned long) lowcore_ptr[cpu], cpu,
				sigp_store_status_at_address);
		} while(rc == sigp_busy);
        }
}

/*
 * this function sends a 'stop' sigp to all other CPUs in the system.
 * it goes straight through.
 */
void smp_send_stop(void)
{
        /* write magic number to zero page (absolute 0) */
	lowcore_ptr[smp_processor_id()]->panic_magic = __PANIC_MAGIC;

	/* stop other processors. */
	do_send_stop();

	/* store status of other processors. */
	do_store_status();
}

/*
 * Reboot, halt and power_off routines for SMP.
 */

static void do_machine_restart(void * __unused)
{
	int cpu;
	static atomic_t cpuid = ATOMIC_INIT(-1);

	if (atomic_compare_and_swap(-1, smp_processor_id(), &cpuid))
		signal_processor(smp_processor_id(), sigp_stop);

	/* Wait for all other cpus to enter stopped state */
	for_each_online_cpu(cpu) {
		if (cpu == smp_processor_id())
			continue;
		while(!smp_cpu_not_running(cpu))
			cpu_relax();
	}

	/* Store status of other cpus. */
	do_store_status();

	/*
	 * Finally call reipl. Because we waited for all other
	 * cpus to enter this function we know that they do
	 * not hold any s390irq-locks (the cpus have been
	 * interrupted by an external interrupt and s390irq
	 * locks are always held disabled).
	 */
	reipl_diag();

	if (MACHINE_IS_VM)
		cpcmd ("IPL", NULL, 0, NULL);
	else
		reipl (0x10000 | S390_lowcore.ipl_device);
}

void machine_restart_smp(char * __unused) 
{
        on_each_cpu(do_machine_restart, NULL, 0, 0);
}

static void do_wait_for_stop(void)
{
	unsigned long cr[16];

	__ctl_store(cr, 0, 15);
	cr[0] &= ~0xffff;
	cr[6] = 0;
	__ctl_load(cr, 0, 15);
	for (;;)
		enabled_wait();
}

static void do_machine_halt(void * __unused)
{
	static atomic_t cpuid = ATOMIC_INIT(-1);

	if (atomic_compare_and_swap(-1, smp_processor_id(), &cpuid) == 0) {
		smp_send_stop();
		if (MACHINE_IS_VM && strlen(vmhalt_cmd) > 0)
			cpcmd(vmhalt_cmd, NULL, 0, NULL);
		signal_processor(smp_processor_id(),
				 sigp_stop_and_store_status);
	}
	do_wait_for_stop();
}

void machine_halt_smp(void)
{
        on_each_cpu(do_machine_halt, NULL, 0, 0);
}

static void do_machine_power_off(void * __unused)
{
	static atomic_t cpuid = ATOMIC_INIT(-1);

	if (atomic_compare_and_swap(-1, smp_processor_id(), &cpuid) == 0) {
		smp_send_stop();
		if (MACHINE_IS_VM && strlen(vmpoff_cmd) > 0)
			cpcmd(vmpoff_cmd, NULL, 0, NULL);
		signal_processor(smp_processor_id(),
				 sigp_stop_and_store_status);
	}
	do_wait_for_stop();
}

void machine_power_off_smp(void)
{
        on_each_cpu(do_machine_power_off, NULL, 0, 0);
}

/*
 * This is the main routine where commands issued by other
 * cpus are handled.
 */

void do_ext_call_interrupt(struct pt_regs *regs, __u16 code)
{
        unsigned long bits;

        /*
         * handle bit signal external calls
         *
         * For the ec_schedule signal we have to do nothing. All the work
         * is done automatically when we return from the interrupt.
         */
	bits = xchg(&S390_lowcore.ext_call_fast, 0);

	if (test_bit(ec_call_function, &bits)) 
		do_call_function();
}

/*
 * Send an external call sigp to another cpu and return without waiting
 * for its completion.
 */
static void smp_ext_bitcall(int cpu, ec_bit_sig sig)
{
        /*
         * Set signaling bit in lowcore of target cpu and kick it
         */
	set_bit(sig, (unsigned long *) &lowcore_ptr[cpu]->ext_call_fast);
	while(signal_processor(cpu, sigp_emergency_signal) == sigp_busy)
		udelay(10);
}

/*
 * Send an external call sigp to every other cpu in the system and
 * return without waiting for its completion.
 */
static void smp_ext_bitcall_others(ec_bit_sig sig)
{
        int cpu;

	for_each_online_cpu(cpu) {
		if (cpu == smp_processor_id())
                        continue;
                /*
                 * Set signaling bit in lowcore of target cpu and kick it
                 */
		set_bit(sig, (unsigned long *) &lowcore_ptr[cpu]->ext_call_fast);
		while (signal_processor(cpu, sigp_emergency_signal) == sigp_busy)
			udelay(10);
        }
}

#ifndef CONFIG_ARCH_S390X
/*
 * this function sends a 'purge tlb' signal to another CPU.
 */
void smp_ptlb_callback(void *info)
{
	local_flush_tlb();
}

void smp_ptlb_all(void)
{
        on_each_cpu(smp_ptlb_callback, NULL, 0, 1);
}
EXPORT_SYMBOL(smp_ptlb_all);
#endif /* ! CONFIG_ARCH_S390X */

/*
 * this function sends a 'reschedule' IPI to another CPU.
 * it goes straight through and wastes no time serializing
 * anything. Worst case is that we lose a reschedule ...
 */
void smp_send_reschedule(int cpu)
{
        smp_ext_bitcall(cpu, ec_schedule);
}