smp.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

/*
 *  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])
 *
 *  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 <asm/sigp.h>
#include <asm/pgalloc.h>
#include <asm/irq.h>
#include <asm/s390_ext.h>
#include <asm/cpcmd.h>

/* prototypes */
extern int cpu_idle(void * unused);

extern __u16 boot_cpu_addr;
extern volatile int __cpu_logical_map[];

/*
 * An array with a pointer the lowcore of every CPU.
 */
static int       max_cpus = NR_CPUS;	  /* Setup configured maximum number of CPUs to activate	*/
int              smp_num_cpus;
struct _lowcore *lowcore_ptr[NR_CPUS];
cycles_t         cacheflush_time=0;
int              smp_threads_ready=0;      /* Set when the idlers are all forked. */
static atomic_t  smp_commenced = ATOMIC_INIT(0);

spinlock_t       kernel_flag __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;

unsigned long	 cpu_online_map;

/*
 *      Setup routine for controlling SMP activation
 *
 *      Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 *      activation entirely (the MPS table probe still happens, though).
 *
 *      Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 *      greater than 0, limits the maximum number of CPUs activated in
 *      SMP mode to <NUM>.
 */

static int __init nosmp(char *str)
{
	max_cpus = 0;
	return 1;
}

__setup("nosmp", nosmp);

static int __init maxcpus(char *str)
{
	get_option(&str, &max_cpus);
	return 1;
}

__setup("maxcpus=", maxcpus);

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

extern void reipl(unsigned long devno);

static sigp_ccode 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 spinlock_t call_lock = SPIN_LOCK_UNLOCKED;

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, you may call it from a bottom half handler.
 */
{
	struct call_data_struct data;
	int cpus = smp_num_cpus-1;

	if (!cpus || !atomic_read(&smp_commenced))
		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;
	/* 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)
		barrier();

	if (wait)
		while (atomic_read(&data.finished) != cpus)
			barrier();
	spin_unlock_bh(&call_lock);

	return 0;
}


/*
 * Various special callbacks
 */

void do_machine_restart(void)
{
        smp_send_stop();
	reipl(S390_lowcore.ipl_device);
}

void machine_restart(char * __unused) 
{
        if (smp_processor_id() != 0) {
                smp_ext_bitcall(0, ec_restart);
                for (;;);
        } else
                do_machine_restart();
}

void do_machine_halt(void)
{
        smp_send_stop();
        if (MACHINE_IS_VM && strlen(vmhalt_cmd) > 0)
                cpcmd(vmhalt_cmd, NULL, 0);
        signal_processor(smp_processor_id(), sigp_stop_and_store_status);
}

void machine_halt(void)
{
        if (smp_processor_id() != 0) {
                smp_ext_bitcall(0, ec_halt);
                for (;;);
        } else
                do_machine_halt();
}

void do_machine_power_off(void)
{
        smp_send_stop();
        if (MACHINE_IS_VM && strlen(vmpoff_cmd) > 0)
                cpcmd(vmpoff_cmd, NULL, 0);
        signal_processor(smp_processor_id(), sigp_stop_and_store_status);
}

void machine_power_off(void)
{
        if (smp_processor_id() != 0) {
                smp_ext_bitcall(0, ec_power_off);
                for (;;);
        } else
                do_machine_power_off();
}

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

void do_ext_call_interrupt(struct pt_regs *regs, __u16 code)
{
        int 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.
	 * For the ec_restart, ec_halt and ec_power_off we call the
         * appropriate routine.
         */
        do {
                bits = atomic_read(&S390_lowcore.ext_call_fast);
        } while (atomic_compare_and_swap(bits,0,&S390_lowcore.ext_call_fast));

        if (test_bit(ec_restart, &bits))
		do_machine_restart();
        if (test_bit(ec_halt, &bits))
		do_machine_halt();
        if (test_bit(ec_power_off, &bits))
		do_machine_power_off();
	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 sigp_ccode smp_ext_bitcall(int cpu, ec_bit_sig sig)
{
        struct _lowcore *lowcore = &get_cpu_lowcore(cpu);
        sigp_ccode ccode;

        /*
         * Set signaling bit in lowcore of target cpu and kick it
         */
        atomic_set_mask(1<<sig, &lowcore->ext_call_fast);
        ccode = signal_processor(cpu, sigp_external_call);
        return ccode;
}

/*
 * 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)
{
        struct _lowcore *lowcore;
        sigp_ccode ccode;
        int i;

        for (i = 0; i < smp_num_cpus; i++) {
                if (smp_processor_id() == i)
                        continue;
                lowcore = &get_cpu_lowcore(i);
                /*
                 * Set signaling bit in lowcore of target cpu and kick it
                 */
                atomic_set_mask(1<<sig, &lowcore->ext_call_fast);
                ccode = signal_processor(i, sigp_external_call);
        }
}

/*
 * this function sends a 'stop' sigp to all other CPUs in the system.
 * it goes straight through.
 */

void smp_send_stop(void)
{
        int i;
        u32 dummy;
        unsigned long low_core_addr;

        /* write magic number to zero page (absolute 0) */

        get_cpu_lowcore(smp_processor_id()).panic_magic = __PANIC_MAGIC;

        /* stop all processors */

        for (i =  0; i < smp_num_cpus; i++) {
                if (smp_processor_id() != i) {
                        int ccode;
                        do {