smp.c

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                atomic_set_mask(1<<sig, &lowcore->ext_call_fast);
                ccode = signal_processor(i, sigp_external_call);
        }
}

/*
 * cycles through all the cpus,
 * returns early if info is not NULL & the processor has something
 * of intrest to report in the info structure.
 * it returns the next cpu to check if it returns early.
 * i.e. it should be used as follows if you wish to receive info.
 * next_cpu=0;
 * do
 * {
 *    info->cpu=next_cpu;
 *    next_cpu=smp_signal_others(order_code,parameter,1,info);
 *    ... check info here
 * } while(next_cpu<=smp_num_cpus)
 *
 *  if you are lazy just use it like
 * smp_signal_others(order_code,parameter,0,1,NULL);
 */
int smp_signal_others(sigp_order_code order_code, u32 parameter,
                      int spin, sigp_info *info)
{
        sigp_ccode   ccode;
        u32          dummy;
        u16          i;

        if (info)
                info->intresting = 0;
        for (i = (info ? info->cpu : 0); i < smp_num_cpus; i++) {
                if (smp_processor_id() != i) {
                        do {
                                ccode = signal_processor_ps(
                                        (info ? &info->status : &dummy),
                                        parameter, i, order_code);
                        } while(spin && ccode == sigp_busy);
                        if (info && ccode != sigp_order_code_accepted) {
                                info->intresting = 1;
                                info->cpu = i;
                                info->ccode = ccode;
                                i++;
                                break;
                        }
                }
        }
        return i;
}

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

void smp_send_stop(void)
{
        smp_signal_others(sigp_stop, 0, 1, NULL);
}

/*
 * 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_call_async(cpu, ec_schedule);
}

/*
 * Set a bit in a control register of all cpus
 */
void smp_ctl_set_bit(int cr, int bit) {
        ec_creg_mask_parms parms;

        if (atomic_read(&smp_commenced) != 0) {
                parms.start_ctl = cr;
                parms.end_ctl = cr;
                parms.orvals[cr] = 1 << bit;
                parms.andvals[cr] = 0xFFFFFFFF;
                smp_ext_call_sync_others(ec_set_ctl_masked,&parms);
        }
        __ctl_set_bit(cr, bit);
}

/*
 * Clear a bit in a control register of all cpus
 */
void smp_ctl_clear_bit(int cr, int bit) {
        ec_creg_mask_parms parms;

        if (atomic_read(&smp_commenced) != 0) {
                parms.start_ctl = cr;
                parms.end_ctl = cr;
                parms.orvals[cr] = 0x00000000;
                parms.andvals[cr] = ~(1 << bit);
                smp_ext_call_sync_others(ec_set_ctl_masked,&parms);
        }
        __ctl_clear_bit(cr, bit);
}


/*
 * Lets check how many CPUs we have.
 */

void smp_count_cpus(void)
{
        int curr_cpu;

        __cpu_logical_map[0] = boot_cpu_addr;
        current->processor = 0;
        smp_num_cpus = 1;
        for (curr_cpu = 0;
             curr_cpu <= 65535 && smp_num_cpus < max_cpus; curr_cpu++) {
                if ((__u16) curr_cpu == boot_cpu_addr)
                        continue;
                __cpu_logical_map[smp_num_cpus] = (__u16) curr_cpu;
                if (signal_processor(smp_num_cpus, sigp_sense) ==
                    sigp_not_operational)
                        continue;
                smp_num_cpus++;
        }
        printk("Detected %d CPU's\n",(int) smp_num_cpus);
        printk("Boot cpu address %2X\n", boot_cpu_addr);
}


/*
 *      Activate a secondary processor.
 */
extern void init_100hz_timer(void);

int __init start_secondary(void *cpuvoid)
{
        /* Setup the cpu */
        cpu_init();
        /* Print info about this processor */
        print_cpu_info(&safe_get_cpu_lowcore(smp_processor_id()).cpu_data);
        /* Wait for completion of smp startup */
        while (!atomic_read(&smp_commenced))
                /* nothing */ ;
        /* init per CPU 100 hz timer */
        init_100hz_timer();
        /* cpu_idle will call schedule for us */
        return cpu_idle(NULL);
}

/*
 * The restart interrupt handler jumps to start_secondary directly
 * without the detour over initialize_secondary. We defined it here
 * so that the linker doesn't complain.
 */
void __init initialize_secondary(void)
{
}

static int __init fork_by_hand(void)
{
       struct pt_regs regs;
       /* don't care about the psw and regs settings since we'll never
          reschedule the forked task. */
       memset(&regs,sizeof(pt_regs),0);
       return do_fork(CLONE_VM|CLONE_PID, 0, &regs, 0);
}

static void __init do_boot_cpu(int cpu)
{
        struct task_struct *idle;
        struct _lowcore    *cpu_lowcore;

        /* We can't use kernel_thread since we must _avoid_ to reschedule
           the child. */
        if (fork_by_hand() < 0)
                panic("failed fork for CPU %d", cpu);

        /*
         * We remove it from the pidhash and the runqueue
         * once we got the process:
         */
        idle = init_task.prev_task;
        if (!idle)
                panic("No idle process for CPU %d",cpu);
        idle->processor = cpu;
        idle->has_cpu = 1; /* we schedule the first task manually */

        del_from_runqueue(idle);
        unhash_process(idle);
        init_tasks[cpu] = idle;

        cpu_lowcore=&get_cpu_lowcore(cpu);
        cpu_lowcore->kernel_stack=idle->thread.ksp;
        __asm__ __volatile__("stctl 0,15,%0\n\t"
                             "stam  0,15,%1"
                             : "=m" (cpu_lowcore->cregs_save_area[0]),
                               "=m" (cpu_lowcore->access_regs_save_area[0])
                             : : "memory");

        eieio();
        signal_processor(cpu,sigp_restart);
}

/*
 *      Architecture specific routine called by the kernel just before init is
 *      fired off. This allows the BP to have everything in order [we hope].
 *      At the end of this all the APs will hit the system scheduling and off
 *      we go. Each AP will load the system gdt's and jump through the kernel
 *      init into idle(). At this point the scheduler will one day take over
 *      and give them jobs to do. smp_callin is a standard routine
 *      we use to track CPUs as they power up.
 */

void __init smp_commence(void)
{
        /*
         *      Lets the callins below out of their loop.
         */
        atomic_set(&smp_commenced,1);
}

/*
 *	Cycle through the processors sending APIC IPIs to boot each.
 */

void __init smp_boot_cpus(void)
{
        struct _lowcore *curr_lowcore;
        sigp_ccode   ccode;
        int i;
        
        smp_count_cpus();
        memset(lowcore_ptr,0,sizeof(lowcore_ptr));  
        
        /*
         *      Initialize the logical to physical CPU number mapping
         *      and the per-CPU profiling counter/multiplier
         */
        
        for (i = 0; i < NR_CPUS; i++) {
                prof_counter[i] = 1;
                prof_old_multiplier[i] = 1;
                prof_multiplier[i] = 1;
        }

        print_cpu_info(&safe_get_cpu_lowcore(0).cpu_data);

        for(i = 0; i < smp_num_cpus; i++)
        {
                curr_lowcore = (struct _lowcore *)
                                    __get_free_page(GFP_KERNEL|GFP_DMA);
                if (curr_lowcore == NULL) {
                        printk("smp_boot_cpus failed to allocate prefix memory\n");
                        break;
                }
                lowcore_ptr[i] = curr_lowcore;
                memcpy(curr_lowcore, &S390_lowcore, sizeof(struct _lowcore));
                /*
                 * Most of the parameters are set up when the cpu is
                 * started up.
                 */
                if (smp_processor_id() == i)
                        set_prefix((u32) curr_lowcore);
                else {
                        ccode = signal_processor_p((u32)(curr_lowcore),
                                                   i, sigp_set_prefix);
                        if(ccode) {
                                /* if this gets troublesome I'll have to do
                                 * something about it. */
                                printk("ccode %d for cpu %d  returned when "
                                       "setting prefix in smp_boot_cpus not good.\n",
                                       (int) ccode, (int) i);
                        }
                        else
                                do_boot_cpu(i);
                }
        }
}

/*
 * the frequency of the profiling timer can be changed
 * by writing a multiplier value into /proc/profile.
 *
 * usually you want to run this on all CPUs ;)
 */
int setup_profiling_timer(unsigned int multiplier)
{
        return 0;
}

/*
 * Local timer interrupt handler. It does both profiling and
 * process statistics/rescheduling.
 *
 * We do profiling in every local tick, statistics/rescheduling
 * happen only every 'profiling multiplier' ticks. The default
 * multiplier is 1 and it can be changed by writing the new multiplier
 * value into /proc/profile.
 */

void smp_local_timer_interrupt(struct pt_regs * regs)
{
	int user = (user_mode(regs) != 0);
        int cpu = smp_processor_id();

        /*
         * The profiling function is SMP safe. (nothing can mess
         * around with "current", and the profiling counters are
         * updated with atomic operations). This is especially
         * useful with a profiling multiplier != 1
         */
        if (!user_mode(regs))
                s390_do_profile(regs->psw.addr);

        if (!--prof_counter[cpu]) {
                int system = 1-user;
                struct task_struct * p = current;

                /*
                 * The multiplier may have changed since the last time we got
                 * to this point as a result of the user writing to
                 * /proc/profile.  In this case we need to adjust the APIC
                 * timer accordingly.
                 *
                 * Interrupts are already masked off at this point.
                 */
                prof_counter[cpu] = prof_multiplier[cpu];
                if (prof_counter[cpu] != prof_old_multiplier[cpu]) {
			/* FIXME setup_APIC_timer(calibration_result/prof_counter[cpu]
			   ); */
                  prof_old_multiplier[cpu] = prof_counter[cpu];
                }

                /*
                 * After doing the above, we need to make like
                 * a normal interrupt - otherwise timer interrupts
                 * ignore the global interrupt lock, which is the
                 * WrongThing (tm) to do.
                 */

                irq_enter(cpu, 0);
                update_one_process(p, 1, user, system, cpu);
                if (p->pid) {
                        p->counter -= 1;
                        if (p->counter <= 0) {
                                p->counter = 0;
                                p->need_resched = 1;
                        }
                        if (p->nice > 0) {
                                kstat.cpu_nice += user;
                                kstat.per_cpu_nice[cpu] += user;
                        } else {
                                kstat.cpu_user += user;
                                kstat.per_cpu_user[cpu] += user;
                        }
                        kstat.cpu_system += system;
                        kstat.per_cpu_system[cpu] += system;

                }
                irq_exit(cpu, 0);
        }
}