/* arch/sparc64/mm/tsb.c
 *
 * Copyright (C) 2006, 2008 David S. Miller <davem@davemloft.net>
 */

#include <linux/kernel.h>
#include <linux/preempt.h>
#include <linux/slab.h>
#include <asm/page.h>
#include <asm/tlbflush.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/tsb.h>
#include <asm/oplib.h>

extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];

static inline unsigned long tsb_hash(unsigned long vaddr, unsigned long hash_shift, unsigned long nentries)
{
        vaddr >>= hash_shift;
        return vaddr & (nentries - 1);
}

static inline int tag_compare(unsigned long tag, unsigned long vaddr)
{
        return (tag == (vaddr >> 22));
}

/* TSB flushes need only occur on the processor initiating the address
 * space modification, not on each cpu the address space has run on.
 * Only the TLB flush needs that treatment.
 */

void flush_tsb_kernel_range(unsigned long start, unsigned long end)
{
        unsigned long v;

        for (v = start; v < end; v += PAGE_SIZE) {
                unsigned long hash = tsb_hash(v, PAGE_SHIFT,
                                              KERNEL_TSB_NENTRIES);
                struct tsb *ent = &swapper_tsb[hash];

                if (tag_compare(ent->tag, v))
                        ent->tag = (1UL << TSB_TAG_INVALID_BIT);
        }
}

static void __flush_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
                            unsigned long tsb, unsigned long nentries)
{
        unsigned long i;

        for (i = 0; i < tb->tlb_nr; i++) {
                unsigned long v = tb->vaddrs[i];
                unsigned long tag, ent, hash;

                v &= ~0x1UL;

                hash = tsb_hash(v, hash_shift, nentries);
                ent = tsb + (hash * sizeof(struct tsb));
                tag = (v >> 22UL);

                tsb_flush(ent, tag);
        }
}

void flush_tsb_user(struct tlb_batch *tb)
{
        struct mm_struct *mm = tb->mm;
        unsigned long nentries, base, flags;

        spin_lock_irqsave(&mm->context.lock, flags);

        base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
        nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
        if (tlb_type == cheetah_plus || tlb_type == hypervisor)
                base = __pa(base);
        __flush_tsb_one(tb, PAGE_SHIFT, base, nentries);

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
        if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
                base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
                nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
                if (tlb_type == cheetah_plus || tlb_type == hypervisor)
                        base = __pa(base);
                __flush_tsb_one(tb, HPAGE_SHIFT, base, nentries);
        }
#endif
        spin_unlock_irqrestore(&mm->context.lock, flags);
}

#define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_8K
#define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_8K

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
#define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_4MB
#define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_4MB
#endif

static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsigned long tsb_bytes)
{
        unsigned long tsb_reg, base, tsb_paddr;
        unsigned long page_sz, tte;

        mm->context.tsb_block[tsb_idx].tsb_nentries =
                tsb_bytes / sizeof(struct tsb);

        base = TSBMAP_BASE;
        tte = pgprot_val(PAGE_KERNEL_LOCKED);
        tsb_paddr = __pa(mm->context.tsb_block[tsb_idx].tsb);
        BUG_ON(tsb_paddr & (tsb_bytes - 1UL));

        /* Use the smallest page size that can map the whole TSB
         * in one TLB entry.
         */
        switch (tsb_bytes) {
        case 8192 << 0:
                tsb_reg = 0x0UL;
#ifdef DCACHE_ALIASING_POSSIBLE
                base += (tsb_paddr & 8192);
#endif
                page_sz = 8192;
                break;

        case 8192 << 1:
                tsb_reg = 0x1UL;
                page_sz = 64 * 1024;
                break;

        case 8192 << 2:
                tsb_reg = 0x2UL;
                page_sz = 64 * 1024;
                break;

        case 8192 << 3:
                tsb_reg = 0x3UL;
                page_sz = 64 * 1024;
                break;

        case 8192 << 4:
                tsb_reg = 0x4UL;
                page_sz = 512 * 1024;
                break;

        case 8192 << 5:
                tsb_reg = 0x5UL;
                page_sz = 512 * 1024;
                break;

        case 8192 << 6:
                tsb_reg = 0x6UL;
                page_sz = 512 * 1024;
                break;

        case 8192 << 7:
                tsb_reg = 0x7UL;
                page_sz = 4 * 1024 * 1024;
                break;

        default:
                printk(KERN_ERR "TSB[%s:%d]: Impossible TSB size %lu, killing process.\n",
                       current->comm, current->pid, tsb_bytes);
                do_exit(SIGSEGV);
        }
        tte |= pte_sz_bits(page_sz);

        if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
                /* Physical mapping, no locked TLB entry for TSB.  */
                tsb_reg |= tsb_paddr;

                mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
                mm->context.tsb_block[tsb_idx].tsb_map_vaddr = 0;
                mm->context.tsb_block[tsb_idx].tsb_map_pte = 0;
        } else {
                tsb_reg |= base;
                tsb_reg |= (tsb_paddr & (page_sz - 1UL));
                tte |= (tsb_paddr & ~(page_sz - 1UL));

                mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
                mm->context.tsb_block[tsb_idx].tsb_map_vaddr = base;
                mm->context.tsb_block[tsb_idx].tsb_map_pte = tte;
        }

        /* Setup the Hypervisor TSB descriptor.  */
        if (tlb_type == hypervisor) {
                struct hv_tsb_descr *hp = &mm->context.tsb_descr[tsb_idx];

                switch (tsb_idx) {
                case MM_TSB_BASE:
                        hp->pgsz_idx = HV_PGSZ_IDX_BASE;
                        break;
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
                case MM_TSB_HUGE:
                        hp->pgsz_idx = HV_PGSZ_IDX_HUGE;
                        break;
#endif
                default:
                        BUG();
                }
                hp->assoc = 1;
                hp->num_ttes = tsb_bytes / 16;
                hp->ctx_idx = 0;
                switch (tsb_idx) {
                case MM_TSB_BASE:
                        hp->pgsz_mask = HV_PGSZ_MASK_BASE;
                        break;
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
                case MM_TSB_HUGE:
                        hp->pgsz_mask = HV_PGSZ_MASK_HUGE;
                        break;
#endif
                default:
                        BUG();
                }
                hp->tsb_base = tsb_paddr;
                hp->resv = 0;
        }
}

struct kmem_cache *pgtable_cache __read_mostly;

static struct kmem_cache *tsb_caches[8] __read_mostly;

static const char *tsb_cache_names[8] = {
        "tsb_8KB",
        "tsb_16KB",
        "tsb_32KB",
        "tsb_64KB",
        "tsb_128KB",
        "tsb_256KB",
        "tsb_512KB",
        "tsb_1MB",
};

void __init pgtable_cache_init(void)
{
        unsigned long i;

        pgtable_cache = kmem_cache_create("pgtable_cache",
                                          PAGE_SIZE, PAGE_SIZE,
                                          0,
                                          _clear_page);
        if (!pgtable_cache) {
                prom_printf("pgtable_cache_init(): Could not create!\n");
                prom_halt();
        }

        for (i = 0; i < 8; i++) {
                unsigned long size = 8192 << i;
                const char *name = tsb_cache_names[i];

                tsb_caches[i] = kmem_cache_create(name,
                                                  size, size,
                                                  0, NULL);
                if (!tsb_caches[i]) {
                        prom_printf("Could not create %s cache\n", name);
                        prom_halt();
                }
        }
}

int sysctl_tsb_ratio = -2;

static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
{
        unsigned long num_ents = (new_size / sizeof(struct tsb));

        if (sysctl_tsb_ratio < 0)
                return num_ents - (num_ents >> -sysctl_tsb_ratio);
        else
                return num_ents + (num_ents >> sysctl_tsb_ratio);
}

/* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
 * do_sparc64_fault() invokes this routine to try and grow it.
 *
 * When we reach the maximum TSB size supported, we stick ~0UL into
 * tsb_rss_limit for that TSB so the grow checks in do_sparc64_fault()
 * will not trigger any longer.
 *
 * The TSB can be anywhere from 8K to 1MB in size, in increasing powers
 * of two.  The TSB must be aligned to it's size, so f.e. a 512K TSB
 * must be 512K aligned.  It also must be physically contiguous, so we
 * cannot use vmalloc().
 *
 * The idea here is to grow the TSB when the RSS of the process approaches
 * the number of entries that the current TSB can hold at once.  Currently,
 * we trigger when the RSS hits 3/4 of the TSB capacity.
 */
void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
{
        unsigned long max_tsb_size = 1 * 1024 * 1024;
        unsigned long new_size, old_size, flags;
        struct tsb *old_tsb, *new_tsb;
        unsigned long new_cache_index, old_cache_index;
        unsigned long new_rss_limit;
        gfp_t gfp_flags;

        if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
                max_tsb_size = (PAGE_SIZE << MAX_ORDER);

        new_cache_index = 0;
        for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
                new_rss_limit = tsb_size_to_rss_limit(new_size);
                if (new_rss_limit > rss)
                        break;
                new_cache_index++;
        }

        if (new_size == max_tsb_size)
                new_rss_limit = ~0UL;

retry_tsb_alloc:
        gfp_flags = GFP_KERNEL;
        if (new_size > (PAGE_SIZE * 2))
                gfp_flags = __GFP_NOWARN | __GFP_NORETRY;

        new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
                                        gfp_flags, numa_node_id());
        if (unlikely(!new_tsb)) {
                /* Not being able to fork due to a high-order TSB
                 * allocation failure is very bad behavior.  Just back
                 * down to a 0-order allocation and force no TSB
                 * growing for this address space.
                 */
                if (mm->context.tsb_block[tsb_index].tsb == NULL &&
                    new_cache_index > 0) {
                        new_cache_index = 0;
                        new_size = 8192;
                        new_rss_limit = ~0UL;
                        goto retry_tsb_alloc;
                }

                /* If we failed on a TSB grow, we are under serious
                 * memory pressure so don't try to grow any more.
                 */
                if (mm->context.tsb_block[tsb_index].tsb != NULL)
                        mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
                return;
        }

        /* Mark all tags as invalid.  */
        tsb_init(new_tsb, new_size);

        /* Ok, we are about to commit the changes.  If we are
         * growing an existing TSB the locking is very tricky,
         * so WATCH OUT!
         *
         * We have to hold mm->context.lock while committing to the
         * new TSB, this synchronizes us with processors in
         * flush_tsb_user() and switch_mm() for this address space.
         *
         * But even with that lock held, processors run asynchronously
         * accessing the old TSB via TLB miss handling.  This is OK
         * because those actions are just propagating state from the
         * Linux page tables into the TSB, page table mappings are not
         * being changed.  If a real fault occurs, the processor will
         * synchronize with us when it hits flush_tsb_user(), this is
         * also true for the case where vmscan is modifying the page
         * tables.  The only thing we need to be careful with is to
         * skip any locked TSB entries during copy_tsb().
         *
         * When we finish committing to the new TSB, we have to drop
         * the lock and ask all other cpus running this address space
         * to run tsb_context_switch() to see the new TSB table.
         */
        spin_lock_irqsave(&mm->context.lock, flags);

        old_tsb = mm->context.tsb_block[tsb_index].tsb;
        old_cache_index =
                (mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
        old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
                    sizeof(struct tsb));


        /* Handle multiple threads trying to grow the TSB at the same time.
         * One will get in here first, and bump the size and the RSS limit.
         * The others will get in here next and hit this check.
         */
        if (unlikely(old_tsb &&
                     (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
                spin_unlock_irqrestore(&mm->context.lock, flags);

                kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
                return;
        }

        mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;

        if (old_tsb) {
                extern void copy_tsb(unsigned long old_tsb_base,
                                     unsigned long old_tsb_size,
                                     unsigned long new_tsb_base,
                                     unsigned long new_tsb_size);
                unsigned long old_tsb_base = (unsigned long) old_tsb;
                unsigned long new_tsb_base = (unsigned long) new_tsb;

                if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
                        old_tsb_base = __pa(old_tsb_base);
                        new_tsb_base = __pa(new_tsb_base);
                }
                copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
        }

        mm->context.tsb_block[tsb_index].tsb = new_tsb;
        setup_tsb_params(mm, tsb_index, new_size);

        spin_unlock_irqrestore(&mm->context.lock, flags);

        /* If old_tsb is NULL, we're being invoked for the first time
         * from init_new_context().
         */
        if (old_tsb) {
                /* Reload it on the local cpu.  */
                tsb_context_switch(mm);

                /* Now force other processors to do the same.  */
                preempt_disable();
                smp_tsb_sync(mm);
                preempt_enable();

                /* Now it is safe to free the old tsb.  */
                kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
        }
}

int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
        unsigned long huge_pte_count;
#endif
        unsigned int i;

        spin_lock_init(&mm->context.lock);

        mm->context.sparc64_ctx_val = 0UL;

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
        /* We reset it to zero because the fork() page copying
         * will re-increment the counters as the parent PTEs are
         * copied into the child address space.
         */
        huge_pte_count = mm->context.huge_pte_count;
        mm->context.huge_pte_count = 0;
#endif

        mm->context.pgtable_page = NULL;

        /* copy_mm() copies over the parent's mm_struct before calling
         * us, so we need to zero out the TSB pointer or else tsb_grow()
         * will be confused and think there is an older TSB to free up.
         */
        for (i = 0; i < MM_NUM_TSBS; i++)
                mm->context.tsb_block[i].tsb = NULL;

        /* If this is fork, inherit the parent's TSB size.  We would
         * grow it to that size on the first page fault anyways.
         */
        tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm));

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
        if (unlikely(huge_pte_count))
                tsb_grow(mm, MM_TSB_HUGE, huge_pte_count);
#endif

        if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
                return -ENOMEM;

        return 0;
}

static void tsb_destroy_one(struct tsb_config *tp)
{
        unsigned long cache_index;

        if (!tp->tsb)
                return;
        cache_index = tp->tsb_reg_val & 0x7UL;
        kmem_cache_free(tsb_caches[cache_index], tp->tsb);
        tp->tsb = NULL;
        tp->tsb_reg_val = 0UL;
}

void destroy_context(struct mm_struct *mm)
{
        unsigned long flags, i;
        struct page *page;

        for (i = 0; i < MM_NUM_TSBS; i++)
                tsb_destroy_one(&mm->context.tsb_block[i]);

        page = mm->context.pgtable_page;
        if (page && put_page_testzero(page)) {
                pgtable_page_dtor(page);
                free_hot_cold_page(page, 0);
        }

        spin_lock_irqsave(&ctx_alloc_lock, flags);

        if (CTX_VALID(mm->context)) {
                unsigned long nr = CTX_NRBITS(mm->context);
                mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
        }

        spin_unlock_irqrestore(&ctx_alloc_lock, flags);
}