tlb.c

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/*
 * TLB support routines.
 *
 * Copyright (C) 1998-2001, 2003 Hewlett-Packard Co
 *  David Mosberger-Tang <[email protected]>
 *
 * 08/02/00 A. Mallick <[email protected]>
 *      Modified RID allocation for SMP
 *          Goutham Rao <[email protected]>
 *              IPI based ptc implementation and A-step IPI implementation.
 * Rohit Seth <[email protected]>
 * Ken Chen <[email protected]>
 * Christophe de Dinechin <[email protected]>: Avoid ptc.e on memory allocation
 * Copyright (C) 2007 Intel Corp
 *  Fenghua Yu <[email protected]>
 *  Add multiple ptc.g/ptc.ga instruction support in global tlb purge.
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/mm.h>
#include <linux/bootmem.h>
#include <linux/slab.h>

#include <asm/delay.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/pal.h>
#include <asm/tlbflush.h>
#include <asm/dma.h>
#include <asm/processor.h>
#include <asm/sal.h>
#include <asm/tlb.h>

static struct {
    u64 mask;       /* mask of supported purge page-sizes */
    unsigned long max_bits; /* log2 of largest supported purge page-size */
} purge;

struct ia64_ctx ia64_ctx = {
    .lock = __SPIN_LOCK_UNLOCKED(ia64_ctx.lock),
    .next = 1,
    .max_ctx = ~0U
};

DEFINE_PER_CPU(u8, ia64_need_tlb_flush);
DEFINE_PER_CPU(u8, ia64_tr_num);  /*Number of TR slots in current processor*/
DEFINE_PER_CPU(u8, ia64_tr_used); /*Max Slot number used by kernel*/

struct ia64_tr_entry *ia64_idtrs[NR_CPUS];

/*
 * Initializes the ia64_ctx.bitmap array based on max_ctx+1.
 * Called after cpu_init() has setup ia64_ctx.max_ctx based on
 * maximum RID that is supported by boot CPU.
 */
void __init
mmu_context_init (void)
{
    ia64_ctx.bitmap = alloc_bootmem((ia64_ctx.max_ctx+1)>>3);
    ia64_ctx.flushmap = alloc_bootmem((ia64_ctx.max_ctx+1)>>3);
}

/*
 * Acquire the ia64_ctx.lock before calling this function!
 */
void
wrap_mmu_context (struct mm_struct *mm)
{
    int i, cpu;
    unsigned long flush_bit;

    for (i=0; i <= ia64_ctx.max_ctx / BITS_PER_LONG; i++) {
        flush_bit = xchg(&ia64_ctx.flushmap[i], 0);
        ia64_ctx.bitmap[i] ^= flush_bit;
    }
 
    /* use offset at 300 to skip daemons */
    ia64_ctx.next = find_next_zero_bit(ia64_ctx.bitmap,
                ia64_ctx.max_ctx, 300);
    ia64_ctx.limit = find_next_bit(ia64_ctx.bitmap,
                ia64_ctx.max_ctx, ia64_ctx.next);

    /*
     * can't call flush_tlb_all() here because of race condition
     * with O(1) scheduler [EF]
     */
    cpu = get_cpu(); /* prevent preemption/migration */
    for_each_online_cpu(i)
        if (i != cpu)
            per_cpu(ia64_need_tlb_flush, i) = 1;
    put_cpu();
    local_flush_tlb_all();
}

/*
 * Implement "spinaphores" ... like counting semaphores, but they
 * spin instead of sleeping.  If there are ever any other users for
 * this primitive it can be moved up to a spinaphore.h header.
 */
struct spinaphore {
    unsigned long   ticket;
    unsigned long   serve;
};

static inline void spinaphore_init(struct spinaphore *ss, int val)
{
    ss->ticket = 0;
    ss->serve = val;
}

static inline void down_spin(struct spinaphore *ss)
{
    unsigned long t = ia64_fetchadd(1, &ss->ticket, acq), serve;

    if (time_before(t, ss->serve))
        return;

    ia64_invala();

    for (;;) {
        asm volatile ("ld8.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");
        if (time_before(t, serve))
            return;
        cpu_relax();
    }
}

static inline void up_spin(struct spinaphore *ss)
{
    ia64_fetchadd(1, &ss->serve, rel);
}

static struct spinaphore ptcg_sem;
static u16 nptcg = 1;
static int need_ptcg_sem = 1;
static int toolatetochangeptcgsem = 0;

/*
 * Kernel parameter "nptcg=" overrides max number of concurrent global TLB
 * purges which is reported from either PAL or SAL PALO.
 *
 * We don't have sanity checking for nptcg value. It's the user's responsibility
 * for valid nptcg value on the platform. Otherwise, kernel may hang in some
 * cases.
 */
static int __init
set_nptcg(char *str)
{
    int value = 0;

    get_option(&str, &value);
    setup_ptcg_sem(value, NPTCG_FROM_KERNEL_PARAMETER);

    return 1;
}

__setup("nptcg=", set_nptcg);

/*
 * Maximum number of simultaneous ptc.g purges in the system can
 * be defined by PAL_VM_SUMMARY (in which case we should take
 * the smallest value for any cpu in the system) or by the PAL
 * override table (in which case we should ignore the value from
 * PAL_VM_SUMMARY).
 *
 * Kernel parameter "nptcg=" overrides maximum number of simultanesous ptc.g
 * purges defined in either PAL_VM_SUMMARY or PAL override table. In this case,
 * we should ignore the value from either PAL_VM_SUMMARY or PAL override table.
 *
 * Complicating the logic here is the fact that num_possible_cpus()
 * isn't fully setup until we start bringing cpus online.
 */
void
setup_ptcg_sem(int max_purges, int nptcg_from)
{
    static int kp_override;
    static int palo_override;
    static int firstcpu = 1;

    if (toolatetochangeptcgsem) {
        if (nptcg_from == NPTCG_FROM_PAL && max_purges == 0)
            BUG_ON(1 < nptcg);
        else
            BUG_ON(max_purges < nptcg);
        return;
    }

    if (nptcg_from == NPTCG_FROM_KERNEL_PARAMETER) {
        kp_override = 1;
        nptcg = max_purges;
        goto resetsema;
    }
    if (kp_override) {
        need_ptcg_sem = num_possible_cpus() > nptcg;
        return;
    }

    if (nptcg_from == NPTCG_FROM_PALO) {
        palo_override = 1;

        /* In PALO max_purges == 0 really means it! */
        if (max_purges == 0)
            panic("Whoa! Platform does not support global TLB purges.\n");
        nptcg = max_purges;
        if (nptcg == PALO_MAX_TLB_PURGES) {
            need_ptcg_sem = 0;
            return;
        }
        goto resetsema;
    }
    if (palo_override) {
        if (nptcg != PALO_MAX_TLB_PURGES)
            need_ptcg_sem = (num_possible_cpus() > nptcg);
        return;
    }

    /* In PAL_VM_SUMMARY max_purges == 0 actually means 1 */
    if (max_purges == 0) max_purges = 1;

    if (firstcpu) {
        nptcg = max_purges;
        firstcpu = 0;
    }
    if (max_purges < nptcg)
        nptcg = max_purges;
    if (nptcg == PAL_MAX_PURGES) {
        need_ptcg_sem = 0;
        return;
    } else
        need_ptcg_sem = (num_possible_cpus() > nptcg);

resetsema:
    spinaphore_init(&ptcg_sem, max_purges);
}

void
ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start,
               unsigned long end, unsigned long nbits)
{
    struct mm_struct *active_mm = current->active_mm;

    toolatetochangeptcgsem = 1;

    if (mm != active_mm) {
        /* Restore region IDs for mm */
        if (mm && active_mm) {
            activate_context(mm);
        } else {
            flush_tlb_all();
            return;
        }
    }

    if (need_ptcg_sem)
        down_spin(&ptcg_sem);

    do {
        /*
         * Flush ALAT entries also.
         */
        ia64_ptcga(start, (nbits << 2));
        ia64_srlz_i();
        start += (1UL << nbits);
    } while (start < end);

    if (need_ptcg_sem)
        up_spin(&ptcg_sem);

        if (mm != active_mm) {
                activate_context(active_mm);
        }
}

void
local_flush_tlb_all (void)
{
    unsigned long i, j, flags, count0, count1, stride0, stride1, addr;

    addr    = local_cpu_data->ptce_base;
    count0  = local_cpu_data->ptce_count[0];
    count1  = local_cpu_data->ptce_count[1];
    stride0 = local_cpu_data->ptce_stride[0];
    stride1 = local_cpu_data->ptce_stride[1];

    local_irq_save(flags);
    for (i = 0; i < count0; ++i) {
        for (j = 0; j < count1; ++j) {
            ia64_ptce(addr);
            addr += stride1;
        }
        addr += stride0;
    }
    local_irq_restore(flags);
    ia64_srlz_i();          /* srlz.i implies srlz.d */
}

void
flush_tlb_range (struct vm_area_struct *vma, unsigned long start,
         unsigned long end)
{
    struct mm_struct *mm = vma->vm_mm;
    unsigned long size = end - start;
    unsigned long nbits;

#ifndef CONFIG_SMP
    if (mm != current->active_mm) {
        mm->context = 0;
        return;
    }
#endif

    nbits = ia64_fls(size + 0xfff);
    while (unlikely (((1UL << nbits) & purge.mask) == 0) &&
            (nbits < purge.max_bits))
        ++nbits;
    if (nbits > purge.max_bits)
        nbits = purge.max_bits;
    start &= ~((1UL << nbits) - 1);

    preempt_disable();
#ifdef CONFIG_SMP
    if (mm != current->active_mm || cpumask_weight(mm_cpumask(mm)) != 1) {
        platform_global_tlb_purge(mm, start, end, nbits);
        preempt_enable();
        return;
    }
#endif
    do {
        ia64_ptcl(start, (nbits<<2));
        start += (1UL << nbits);
    } while (start < end);
    preempt_enable();
    ia64_srlz_i();          /* srlz.i implies srlz.d */
}
EXPORT_SYMBOL(flush_tlb_range);

void __devinit
ia64_tlb_init (void)
{
    ia64_ptce_info_t uninitialized_var(ptce_info); /* GCC be quiet */
    u64 tr_pgbits;
    long status;
    pal_vm_info_1_u_t vm_info_1;
    pal_vm_info_2_u_t vm_info_2;
    int cpu = smp_processor_id();

    if ((status = ia64_pal_vm_page_size(&tr_pgbits, &purge.mask)) != 0) {
        printk(KERN_ERR "PAL_VM_PAGE_SIZE failed with status=%ld; "
               "defaulting to architected purge page-sizes.\n", status);
        purge.mask = 0x115557000UL;
    }
    purge.max_bits = ia64_fls(purge.mask);

    ia64_get_ptce(&ptce_info);
    local_cpu_data->ptce_base = ptce_info.base;
    local_cpu_data->ptce_count[0] = ptce_info.count[0];
    local_cpu_data->ptce_count[1] = ptce_info.count[1];
    local_cpu_data->ptce_stride[0] = ptce_info.stride[0];
    local_cpu_data->ptce_stride[1] = ptce_info.stride[1];

    local_flush_tlb_all();  /* nuke left overs from bootstrapping... */
    status = ia64_pal_vm_summary(&vm_info_1, &vm_info_2);

    if (status) {
        printk(KERN_ERR "ia64_pal_vm_summary=%ld\n", status);
        per_cpu(ia64_tr_num, cpu) = 8;
        return;
    }
    per_cpu(ia64_tr_num, cpu) = vm_info_1.pal_vm_info_1_s.max_itr_entry+1;
    if (per_cpu(ia64_tr_num, cpu) >
                (vm_info_1.pal_vm_info_1_s.max_dtr_entry+1))
        per_cpu(ia64_tr_num, cpu) =
                vm_info_1.pal_vm_info_1_s.max_dtr_entry+1;
    if (per_cpu(ia64_tr_num, cpu) > IA64_TR_ALLOC_MAX) {
        static int justonce = 1;
        per_cpu(ia64_tr_num, cpu) = IA64_TR_ALLOC_MAX;
        if (justonce) {
            justonce = 0;
            printk(KERN_DEBUG "TR register number exceeds "
                   "IA64_TR_ALLOC_MAX!\n");
        }
    }
}

/*
 * is_tr_overlap
 *
 * Check overlap with inserted TRs.
 */
static int is_tr_overlap(struct ia64_tr_entry *p, u64 va, u64 log_size)
{
    u64 tr_log_size;
    u64 tr_end;
    u64 va_rr = ia64_get_rr(va);
    u64 va_rid = RR_TO_RID(va_rr);
    u64 va_end = va + (1<<log_size) - 1;

    if (va_rid != RR_TO_RID(p->rr))
        return 0;
    tr_log_size = (p->itir & 0xff) >> 2;
    tr_end = p->ifa + (1<<tr_log_size) - 1;

    if (va > tr_end || p->ifa > va_end)
        return 0;
    return 1;

}

/*
 * ia64_insert_tr in virtual mode. Allocate a TR slot
 *
 * target_mask : 0x1 : itr, 0x2 : dtr, 0x3 : idtr
 *
 * va   : virtual address.
 * pte  : pte entries inserted.
 * log_size: range to be covered.
 *
 * Return value:  <0 :  error No.
 *
 *        >=0 : slot number allocated for TR.
 * Must be called with preemption disabled.
 */
int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size)
{
    int i, r;
    unsigned long psr;
    struct ia64_tr_entry *p;
    int cpu = smp_processor_id();

    if (!ia64_idtrs[cpu]) {
        ia64_idtrs[cpu] = kmalloc(2 * IA64_TR_ALLOC_MAX *
                sizeof (struct ia64_tr_entry), GFP_KERNEL);
        if (!ia64_idtrs[cpu])
            return -ENOMEM;
    }
    r = -EINVAL;
    /*Check overlap with existing TR entries*/
    if (target_mask & 0x1) {
        p = ia64_idtrs[cpu];
        for (i = IA64_TR_ALLOC_BASE; i <= per_cpu(ia64_tr_used, cpu);
                                i++, p++) {
            if (p->pte & 0x1)
                if (is_tr_overlap(p, va, log_size)) {
                    printk(KERN_DEBUG "Overlapped Entry"
                        "Inserted for TR Reigster!!\n");
                    goto out;
            }
        }
    }
    if (target_mask & 0x2) {
        p = ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX;
        for (i = IA64_TR_ALLOC_BASE; i <= per_cpu(ia64_tr_used, cpu);
                                i++, p++) {
            if (p->pte & 0x1)
                if (is_tr_overlap(p, va, log_size)) {
                    printk(KERN_DEBUG "Overlapped Entry"
                        "Inserted for TR Reigster!!\n");
                    goto out;
                }
        }
    }

    for (i = IA64_TR_ALLOC_BASE; i < per_cpu(ia64_tr_num, cpu); i++) {
        switch (target_mask & 0x3) {
        case 1:
            if (!((ia64_idtrs[cpu] + i)->pte & 0x1))
                goto found;
            continue;
        case 2:
            if (!((ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i)->pte & 0x1))
                goto found;
            continue;
        case 3:
            if (!((ia64_idtrs[cpu] + i)->pte & 0x1) &&
                !((ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i)->pte & 0x1))
                goto found;
            continue;
        default:
            r = -EINVAL;
            goto out;
        }
    }
found:
    if (i >= per_cpu(ia64_tr_num, cpu))
        return -EBUSY;

    /*Record tr info for mca hander use!*/
    if (i > per_cpu(ia64_tr_used, cpu))
        per_cpu(ia64_tr_used, cpu) = i;

    psr = ia64_clear_ic();
    if (target_mask & 0x1) {
        ia64_itr(0x1, i, va, pte, log_size);
        ia64_srlz_i();
        p = ia64_idtrs[cpu] + i;
        p->ifa = va;
        p->pte = pte;
        p->itir = log_size << 2;
        p->rr = ia64_get_rr(va);
    }
    if (target_mask & 0x2) {
        ia64_itr(0x2, i, va, pte, log_size);
        ia64_srlz_i();
        p = ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i;
        p->ifa = va;
        p->pte = pte;
        p->itir = log_size << 2;
        p->rr = ia64_get_rr(va);
    }
    ia64_set_psr(psr);
    r = i;
out:
    return r;
}
EXPORT_SYMBOL_GPL(ia64_itr_entry);

/*
 * ia64_purge_tr
 *
 * target_mask: 0x1: purge itr, 0x2 : purge dtr, 0x3 purge idtr.
 * slot: slot number to be freed.
 *
 * Must be called with preemption disabled.
 */
void ia64_ptr_entry(u64 target_mask, int slot)
{
    int cpu = smp_processor_id();
    int i;
    struct ia64_tr_entry *p;

    if (slot < IA64_TR_ALLOC_BASE || slot >= per_cpu(ia64_tr_num, cpu))
        return;

    if (target_mask & 0x1) {
        p = ia64_idtrs[cpu] + slot;
        if ((p->pte&0x1) && is_tr_overlap(p, p->ifa, p->itir>>2)) {
            p->pte = 0;
            ia64_ptr(0x1, p->ifa, p->itir>>2);
            ia64_srlz_i();
        }
    }

    if (target_mask & 0x2) {
        p = ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + slot;
        if ((p->pte & 0x1) && is_tr_overlap(p, p->ifa, p->itir>>2)) {
            p->pte = 0;
            ia64_ptr(0x2, p->ifa, p->itir>>2);
            ia64_srlz_i();
        }
    }

    for (i = per_cpu(ia64_tr_used, cpu); i >= IA64_TR_ALLOC_BASE; i--) {
        if (((ia64_idtrs[cpu] + i)->pte & 0x1) ||
            ((ia64_idtrs[cpu] + IA64_TR_ALLOC_MAX + i)->pte & 0x1))
            break;
    }
    per_cpu(ia64_tr_used, cpu) = i;
}
EXPORT_SYMBOL_GPL(ia64_ptr_entry);