[IA64] Re-implement spinaphores using ticket lock concepts

[linux-2.6/btrfs-unstable.git] / arch / ia64 / mm / tlb.c

/*
 * TLB support routines.
 *
 * Copyright (C) 1998-2001, 2003 Hewlett-Packard Co
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * 08/02/00 A. Mallick <asit.k.mallick@intel.com>
 *              Modified RID allocation for SMP
 *          Goutham Rao <goutham.rao@intel.com>
 *              IPI based ptc implementation and A-step IPI implementation.
 * Rohit Seth <rohit.seth@intel.com>
 * Ken Chen <kenneth.w.chen@intel.com>
 * Christophe de Dinechin <ddd@hp.com>: Avoid ptc.e on memory allocation
 * Copyright (C) 2007 Intel Corp
 *      Fenghua Yu <fenghua.yu@intel.com>
 *      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 <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 __per_cpu_idtrs[NR_CPUS][2][IA64_TR_ALLOC_MAX];

/*
 * 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 ("ld4.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();

        r = -EINVAL;
        /*Check overlap with existing TR entries*/
        if (target_mask & 0x1) {
                p = &__per_cpu_idtrs[cpu][0][0];
                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 = &__per_cpu_idtrs[cpu][1][0];
                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 (!(__per_cpu_idtrs[cpu][0][i].pte & 0x1))
                                goto found;
                        continue;
                case 2:
                        if (!(__per_cpu_idtrs[cpu][1][i].pte & 0x1))
                                goto found;
                        continue;
                case 3:
                        if (!(__per_cpu_idtrs[cpu][0][i].pte & 0x1) &&
                                !(__per_cpu_idtrs[cpu][1][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 = &__per_cpu_idtrs[cpu][0][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 = &__per_cpu_idtrs[cpu][1][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 = &__per_cpu_idtrs[cpu][0][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 = &__per_cpu_idtrs[cpu][1][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 ((__per_cpu_idtrs[cpu][0][i].pte & 0x1) ||
                                (__per_cpu_idtrs[cpu][1][i].pte & 0x1))
                        break;
        }
        per_cpu(ia64_tr_used, cpu) = i;
}
EXPORT_SYMBOL_GPL(ia64_ptr_entry);