sn2_smp.c

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/*
 * SN2 Platform specific SMP Support
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2000-2006 Silicon Graphics, Inc. All rights reserved.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/mmzone.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/nodemask.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>

#include <asm/processor.h>
#include <asm/irq.h>
#include <asm/sal.h>
#include <asm/delay.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/tlb.h>
#include <asm/numa.h>
#include <asm/hw_irq.h>
#include <asm/current.h>
#include <asm/sn/sn_cpuid.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/addrs.h>
#include <asm/sn/shub_mmr.h>
#include <asm/sn/nodepda.h>
#include <asm/sn/rw_mmr.h>
#include <asm/sn/sn_feature_sets.h>

DEFINE_PER_CPU(struct ptc_stats, ptcstats);
DECLARE_PER_CPU(struct ptc_stats, ptcstats);

static  __cacheline_aligned DEFINE_SPINLOCK(sn2_global_ptc_lock);

/* 0 = old algorithm (no IPI flushes), 1 = ipi deadlock flush, 2 = ipi instead of SHUB ptc, >2 = always ipi */
static int sn2_flush_opt = 0;

extern unsigned long
sn2_ptc_deadlock_recovery_core(volatile unsigned long *, unsigned long,
                   volatile unsigned long *, unsigned long,
                   volatile unsigned long *, unsigned long);
void
sn2_ptc_deadlock_recovery(short *, short, short, int,
              volatile unsigned long *, unsigned long,
              volatile unsigned long *, unsigned long);

/*
 * Note: some is the following is captured here to make degugging easier
 * (the macros make more sense if you see the debug patch - not posted)
 */
#define sn2_ptctest 0
#define local_node_uses_ptc_ga(sh1) ((sh1) ? 1 : 0)
#define max_active_pio(sh1)     ((sh1) ? 32 : 7)
#define reset_max_active_on_deadlock()  1
#define PTC_LOCK(sh1)           ((sh1) ? &sn2_global_ptc_lock : &sn_nodepda->ptc_lock)

struct ptc_stats {
    unsigned long ptc_l;
    unsigned long change_rid;
    unsigned long shub_ptc_flushes;
    unsigned long nodes_flushed;
    unsigned long deadlocks;
    unsigned long deadlocks2;
    unsigned long lock_itc_clocks;
    unsigned long shub_itc_clocks;
    unsigned long shub_itc_clocks_max;
    unsigned long shub_ptc_flushes_not_my_mm;
    unsigned long shub_ipi_flushes;
    unsigned long shub_ipi_flushes_itc_clocks;
};

#define sn2_ptctest 0

static inline unsigned long wait_piowc(void)
{
    volatile unsigned long *piows;
    unsigned long zeroval, ws;

    piows = pda->pio_write_status_addr;
    zeroval = pda->pio_write_status_val;
    do {
        cpu_relax();
    } while (((ws = *piows) & SH_PIO_WRITE_STATUS_PENDING_WRITE_COUNT_MASK) != zeroval);
    return (ws & SH_PIO_WRITE_STATUS_WRITE_DEADLOCK_MASK) != 0;
}

void sn_migrate(struct task_struct *task)
{
    pda_t *last_pda = pdacpu(task_thread_info(task)->last_cpu);
    volatile unsigned long *adr = last_pda->pio_write_status_addr;
    unsigned long val = last_pda->pio_write_status_val;

    /* Drain PIO writes from old CPU's Shub */
    while (unlikely((*adr & SH_PIO_WRITE_STATUS_PENDING_WRITE_COUNT_MASK)
            != val))
        cpu_relax();
}

void sn_tlb_migrate_finish(struct mm_struct *mm)
{
    /* flush_tlb_mm is inefficient if more than 1 users of mm */
    if (mm == current->mm && mm && atomic_read(&mm->mm_users) == 1)
        flush_tlb_mm(mm);
}

static void
sn2_ipi_flush_all_tlb(struct mm_struct *mm)
{
    unsigned long itc;

    itc = ia64_get_itc();
    smp_flush_tlb_cpumask(*mm_cpumask(mm));
    itc = ia64_get_itc() - itc;
    __get_cpu_var(ptcstats).shub_ipi_flushes_itc_clocks += itc;
    __get_cpu_var(ptcstats).shub_ipi_flushes++;
}

void
sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
             unsigned long end, unsigned long nbits)
{
    int i, ibegin, shub1, cnode, mynasid, cpu, lcpu = 0, nasid;
    int mymm = (mm == current->active_mm && mm == current->mm);
    int use_cpu_ptcga;
    volatile unsigned long *ptc0, *ptc1;
    unsigned long itc, itc2, flags, data0 = 0, data1 = 0, rr_value, old_rr = 0;
    short nasids[MAX_NUMNODES], nix;
    nodemask_t nodes_flushed;
    int active, max_active, deadlock, flush_opt = sn2_flush_opt;

    if (flush_opt > 2) {
        sn2_ipi_flush_all_tlb(mm);
        return;
    }

    nodes_clear(nodes_flushed);
    i = 0;

    for_each_cpu(cpu, mm_cpumask(mm)) {
        cnode = cpu_to_node(cpu);
        node_set(cnode, nodes_flushed);
        lcpu = cpu;
        i++;
    }

    if (i == 0)
        return;

    preempt_disable();

    if (likely(i == 1 && lcpu == smp_processor_id() && mymm)) {
        do {
            ia64_ptcl(start, nbits << 2);
            start += (1UL << nbits);
        } while (start < end);
        ia64_srlz_i();
        __get_cpu_var(ptcstats).ptc_l++;
        preempt_enable();
        return;
    }

    if (atomic_read(&mm->mm_users) == 1 && mymm) {
        flush_tlb_mm(mm);
        __get_cpu_var(ptcstats).change_rid++;
        preempt_enable();
        return;
    }

    if (flush_opt == 2) {
        sn2_ipi_flush_all_tlb(mm);
        preempt_enable();
        return;
    }

    itc = ia64_get_itc();
    nix = 0;
    for_each_node_mask(cnode, nodes_flushed)
        nasids[nix++] = cnodeid_to_nasid(cnode);

    rr_value = (mm->context << 3) | REGION_NUMBER(start);

    shub1 = is_shub1();
    if (shub1) {
        data0 = (1UL << SH1_PTC_0_A_SHFT) |
                (nbits << SH1_PTC_0_PS_SHFT) |
            (rr_value << SH1_PTC_0_RID_SHFT) |
                (1UL << SH1_PTC_0_START_SHFT);
        ptc0 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH1_PTC_0);
        ptc1 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH1_PTC_1);
    } else {
        data0 = (1UL << SH2_PTC_A_SHFT) |
            (nbits << SH2_PTC_PS_SHFT) |
                (1UL << SH2_PTC_START_SHFT);
        ptc0 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH2_PTC + 
            (rr_value << SH2_PTC_RID_SHFT));
        ptc1 = NULL;
    }
    

    mynasid = get_nasid();
    use_cpu_ptcga = local_node_uses_ptc_ga(shub1);
    max_active = max_active_pio(shub1);

    itc = ia64_get_itc();
    spin_lock_irqsave(PTC_LOCK(shub1), flags);
    itc2 = ia64_get_itc();

    __get_cpu_var(ptcstats).lock_itc_clocks += itc2 - itc;
    __get_cpu_var(ptcstats).shub_ptc_flushes++;
    __get_cpu_var(ptcstats).nodes_flushed += nix;
    if (!mymm)
         __get_cpu_var(ptcstats).shub_ptc_flushes_not_my_mm++;

    if (use_cpu_ptcga && !mymm) {
        old_rr = ia64_get_rr(start);
        ia64_set_rr(start, (old_rr & 0xff) | (rr_value << 8));
        ia64_srlz_d();
    }

    wait_piowc();
    do {
        if (shub1)
            data1 = start | (1UL << SH1_PTC_1_START_SHFT);
        else
            data0 = (data0 & ~SH2_PTC_ADDR_MASK) | (start & SH2_PTC_ADDR_MASK);
        deadlock = 0;
        active = 0;
        for (ibegin = 0, i = 0; i < nix; i++) {
            nasid = nasids[i];
            if (use_cpu_ptcga && unlikely(nasid == mynasid)) {
                ia64_ptcga(start, nbits << 2);
                ia64_srlz_i();
            } else {
                ptc0 = CHANGE_NASID(nasid, ptc0);
                if (ptc1)
                    ptc1 = CHANGE_NASID(nasid, ptc1);
                pio_atomic_phys_write_mmrs(ptc0, data0, ptc1, data1);
                active++;
            }
            if (active >= max_active || i == (nix - 1)) {
                if ((deadlock = wait_piowc())) {
                    if (flush_opt == 1)
                        goto done;
                    sn2_ptc_deadlock_recovery(nasids, ibegin, i, mynasid, ptc0, data0, ptc1, data1);
                    if (reset_max_active_on_deadlock())
                        max_active = 1;
                }
                active = 0;
                ibegin = i + 1;
            }
        }
        start += (1UL << nbits);
    } while (start < end);

done:
    itc2 = ia64_get_itc() - itc2;
    __get_cpu_var(ptcstats).shub_itc_clocks += itc2;
    if (itc2 > __get_cpu_var(ptcstats).shub_itc_clocks_max)
        __get_cpu_var(ptcstats).shub_itc_clocks_max = itc2;

    if (old_rr) {
        ia64_set_rr(start, old_rr);
        ia64_srlz_d();
    }

    spin_unlock_irqrestore(PTC_LOCK(shub1), flags);

    if (flush_opt == 1 && deadlock) {
        __get_cpu_var(ptcstats).deadlocks++;
        sn2_ipi_flush_all_tlb(mm);
    }

    preempt_enable();
}

/*
 * sn2_ptc_deadlock_recovery
 *
 * Recover from PTC deadlocks conditions. Recovery requires stepping thru each 
 * TLB flush transaction.  The recovery sequence is somewhat tricky & is
 * coded in assembly language.
 */

void
sn2_ptc_deadlock_recovery(short *nasids, short ib, short ie, int mynasid,
              volatile unsigned long *ptc0, unsigned long data0,
              volatile unsigned long *ptc1, unsigned long data1)
{
    short nasid, i;
    unsigned long *piows, zeroval, n;

    __get_cpu_var(ptcstats).deadlocks++;

    piows = (unsigned long *) pda->pio_write_status_addr;
    zeroval = pda->pio_write_status_val;


    for (i=ib; i <= ie; i++) {
        nasid = nasids[i];
        if (local_node_uses_ptc_ga(is_shub1()) && nasid == mynasid)
            continue;
        ptc0 = CHANGE_NASID(nasid, ptc0);
        if (ptc1)
            ptc1 = CHANGE_NASID(nasid, ptc1);

        n = sn2_ptc_deadlock_recovery_core(ptc0, data0, ptc1, data1, piows, zeroval);
        __get_cpu_var(ptcstats).deadlocks2 += n;
    }

}

void sn_send_IPI_phys(int nasid, long physid, int vector, int delivery_mode)
{
    long val;
    unsigned long flags = 0;
    volatile long *p;

    p = (long *)GLOBAL_MMR_PHYS_ADDR(nasid, SH_IPI_INT);
    val = (1UL << SH_IPI_INT_SEND_SHFT) |
        (physid << SH_IPI_INT_PID_SHFT) |
        ((long)delivery_mode << SH_IPI_INT_TYPE_SHFT) |
        ((long)vector << SH_IPI_INT_IDX_SHFT) |
        (0x000feeUL << SH_IPI_INT_BASE_SHFT);

    mb();
    if (enable_shub_wars_1_1()) {
        spin_lock_irqsave(&sn2_global_ptc_lock, flags);
    }
    pio_phys_write_mmr(p, val);
    if (enable_shub_wars_1_1()) {
        wait_piowc();
        spin_unlock_irqrestore(&sn2_global_ptc_lock, flags);
    }

}

EXPORT_SYMBOL(sn_send_IPI_phys);

void sn2_send_IPI(int cpuid, int vector, int delivery_mode, int redirect)
{
    long physid;
    int nasid;

    physid = cpu_physical_id(cpuid);
    nasid = cpuid_to_nasid(cpuid);

    /* the following is used only when starting cpus at boot time */
    if (unlikely(nasid == -1))
        ia64_sn_get_sapic_info(physid, &nasid, NULL, NULL);

    sn_send_IPI_phys(nasid, physid, vector, delivery_mode);
}

#ifdef CONFIG_HOTPLUG_CPU

bool sn_cpu_disable_allowed(int cpu)
{
    if (is_shub2() && sn_prom_feature_available(PRF_CPU_DISABLE_SUPPORT)) {
        if (cpu != 0)
            return true;
        else
            printk(KERN_WARNING
                  "Disabling the boot processor is not allowed.\n");

    } else
        printk(KERN_WARNING
               "CPU disable is not supported on this system.\n");

    return false;
}
#endif /* CONFIG_HOTPLUG_CPU */

#ifdef CONFIG_PROC_FS

#define PTC_BASENAME    "sgi_sn/ptc_statistics"

static void *sn2_ptc_seq_start(struct seq_file *file, loff_t * offset)
{
    if (*offset < nr_cpu_ids)
        return offset;
    return NULL;
}

static void *sn2_ptc_seq_next(struct seq_file *file, void *data, loff_t * offset)
{
    (*offset)++;
    if (*offset < nr_cpu_ids)
        return offset;
    return NULL;
}

static void sn2_ptc_seq_stop(struct seq_file *file, void *data)
{
}

static int sn2_ptc_seq_show(struct seq_file *file, void *data)
{
    struct ptc_stats *stat;
    int cpu;

    cpu = *(loff_t *) data;

    if (!cpu) {
        seq_printf(file,
               "# cpu ptc_l newrid ptc_flushes nodes_flushed deadlocks lock_nsec shub_nsec shub_nsec_max not_my_mm deadlock2 ipi_fluches ipi_nsec\n");
        seq_printf(file, "# ptctest %d, flushopt %d\n", sn2_ptctest, sn2_flush_opt);
    }

    if (cpu < nr_cpu_ids && cpu_online(cpu)) {
        stat = &per_cpu(ptcstats, cpu);
        seq_printf(file, "cpu %d %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld\n", cpu, stat->ptc_l,
                stat->change_rid, stat->shub_ptc_flushes, stat->nodes_flushed,
                stat->deadlocks,
                1000 * stat->lock_itc_clocks / per_cpu(ia64_cpu_info, cpu).cyc_per_usec,
                1000 * stat->shub_itc_clocks / per_cpu(ia64_cpu_info, cpu).cyc_per_usec,
                1000 * stat->shub_itc_clocks_max / per_cpu(ia64_cpu_info, cpu).cyc_per_usec,
                stat->shub_ptc_flushes_not_my_mm,
                stat->deadlocks2,
                stat->shub_ipi_flushes,
                1000 * stat->shub_ipi_flushes_itc_clocks / per_cpu(ia64_cpu_info, cpu).cyc_per_usec);
    }
    return 0;
}

static ssize_t sn2_ptc_proc_write(struct file *file, const char __user *user, size_t count, loff_t *data)
{
    int cpu;
    char optstr[64];

    if (count == 0 || count > sizeof(optstr))
        return -EINVAL;
    if (copy_from_user(optstr, user, count))
        return -EFAULT;
    optstr[count - 1] = '\0';
    sn2_flush_opt = simple_strtoul(optstr, NULL, 0);

    for_each_online_cpu(cpu)
        memset(&per_cpu(ptcstats, cpu), 0, sizeof(struct ptc_stats));

    return count;
}

static const struct seq_operations sn2_ptc_seq_ops = {
    .start = sn2_ptc_seq_start,
    .next = sn2_ptc_seq_next,
    .stop = sn2_ptc_seq_stop,
    .show = sn2_ptc_seq_show
};

static int sn2_ptc_proc_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &sn2_ptc_seq_ops);
}

static const struct file_operations proc_sn2_ptc_operations = {
    .open = sn2_ptc_proc_open,
    .read = seq_read,
    .write = sn2_ptc_proc_write,
    .llseek = seq_lseek,
    .release = seq_release,
};

static struct proc_dir_entry *proc_sn2_ptc;

static int __init sn2_ptc_init(void)
{
    if (!ia64_platform_is("sn2"))
        return 0;

    proc_sn2_ptc = proc_create(PTC_BASENAME, 0444,
                   NULL, &proc_sn2_ptc_operations);
    if (!proc_sn2_ptc) {
        printk(KERN_ERR "unable to create %s proc entry", PTC_BASENAME);
        return -EINVAL;
    }
    spin_lock_init(&sn2_global_ptc_lock);
    return 0;
}

static void __exit sn2_ptc_exit(void)
{
    remove_proc_entry(PTC_BASENAME, NULL);
}

module_init(sn2_ptc_init);
module_exit(sn2_ptc_exit);
#endif /* CONFIG_PROC_FS */