/* arch/sparc64/mm/tlb.c
 *
 * Copyright (C) 2004 David S. Miller <davem@redhat.com>
 */

#include <linux/kernel.h>
#include <linux/percpu.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/preempt.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/tlb.h>

/* Heavily inspired by the ppc64 code.  */

static DEFINE_PER_CPU(struct tlb_batch, tlb_batch);

void flush_tlb_pending(void)
{
        struct tlb_batch *tb = &get_cpu_var(tlb_batch);
        struct mm_struct *mm = tb->mm;

        if (!tb->tlb_nr)
                goto out;

        flush_tsb_user(tb);

        if (CTX_VALID(mm->context)) {
                if (tb->tlb_nr == 1) {
                        global_flush_tlb_page(mm, tb->vaddrs[0]);
                } else {
#ifdef CONFIG_SMP
                        smp_flush_tlb_pending(tb->mm, tb->tlb_nr,
                                              &tb->vaddrs[0]);
#else
                        __flush_tlb_pending(CTX_HWBITS(tb->mm->context),
                                            tb->tlb_nr, &tb->vaddrs[0]);
#endif
                }
        }

        tb->tlb_nr = 0;

out:
        put_cpu_var(tlb_batch);
}

void arch_enter_lazy_mmu_mode(void)
{
        struct tlb_batch *tb = this_cpu_ptr(&tlb_batch);

        tb->active = 1;
}

void arch_leave_lazy_mmu_mode(void)
{
        struct tlb_batch *tb = this_cpu_ptr(&tlb_batch);

        if (tb->tlb_nr)
                flush_tlb_pending();
        tb->active = 0;
}

static void tlb_batch_add_one(struct mm_struct *mm, unsigned long vaddr,
                              bool exec, bool huge)
{
        struct tlb_batch *tb = &get_cpu_var(tlb_batch);
        unsigned long nr;

        vaddr &= PAGE_MASK;
        if (exec)
                vaddr |= 0x1UL;

        nr = tb->tlb_nr;

        if (unlikely(nr != 0 && mm != tb->mm)) {
                flush_tlb_pending();
                nr = 0;
        }

        if (!tb->active) {
                flush_tsb_user_page(mm, vaddr, huge);
                global_flush_tlb_page(mm, vaddr);
                goto out;
        }

        if (nr == 0) {
                tb->mm = mm;
                tb->huge = huge;
        }

        if (tb->huge != huge) {
                flush_tlb_pending();
                tb->huge = huge;
                nr = 0;
        }

        tb->vaddrs[nr] = vaddr;
        tb->tlb_nr = ++nr;
        if (nr >= TLB_BATCH_NR)
                flush_tlb_pending();

out:
        put_cpu_var(tlb_batch);
}

void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr,
                   pte_t *ptep, pte_t orig, int fullmm)
{
        bool huge = is_hugetlb_pte(orig);

        if (tlb_type != hypervisor &&
            pte_dirty(orig)) {
                unsigned long paddr, pfn = pte_pfn(orig);
                struct address_space *mapping;
                struct page *page;

                if (!pfn_valid(pfn))
                        goto no_cache_flush;

                page = pfn_to_page(pfn);
                if (PageReserved(page))
                        goto no_cache_flush;

                /* A real file page? */
                mapping = page_mapping(page);
                if (!mapping)
                        goto no_cache_flush;

                paddr = (unsigned long) page_address(page);
                if ((paddr ^ vaddr) & (1 << 13))
                        flush_dcache_page_all(mm, page);
        }

no_cache_flush:
        if (!fullmm)
                tlb_batch_add_one(mm, vaddr, pte_exec(orig), huge);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void tlb_batch_pmd_scan(struct mm_struct *mm, unsigned long vaddr,
                               pmd_t pmd)
{
        unsigned long end;
        pte_t *pte;

        pte = pte_offset_map(&pmd, vaddr);
        end = vaddr + HPAGE_SIZE;
        while (vaddr < end) {
                if (pte_val(*pte) & _PAGE_VALID) {
                        bool exec = pte_exec(*pte);

                        tlb_batch_add_one(mm, vaddr, exec, false);
                }
                pte++;
                vaddr += PAGE_SIZE;
        }
        pte_unmap(pte);
}

void set_pmd_at(struct mm_struct *mm, unsigned long addr,
                pmd_t *pmdp, pmd_t pmd)
{
        pmd_t orig = *pmdp;

        *pmdp = pmd;

        if (mm == &init_mm)
                return;

        if ((pmd_val(pmd) ^ pmd_val(orig)) & _PAGE_PMD_HUGE) {
                /*
                 * Note that this routine only sets pmds for THP pages.
                 * Hugetlb pages are handled elsewhere.  We need to check
                 * for huge zero page.  Huge zero pages are like hugetlb
                 * pages in that there is no RSS, but there is the need
                 * for TSB entries.  So, huge zero page counts go into
                 * hugetlb_pte_count.
                 */
                if (pmd_val(pmd) & _PAGE_PMD_HUGE) {
                        if (is_huge_zero_page(pmd_page(pmd)))
                                mm->context.hugetlb_pte_count++;
                        else
                                mm->context.thp_pte_count++;
                } else {
                        if (is_huge_zero_page(pmd_page(orig)))
                                mm->context.hugetlb_pte_count--;
                        else
                                mm->context.thp_pte_count--;
                }

                /* Do not try to allocate the TSB hash table if we
                 * don't have one already.  We have various locks held
                 * and thus we'll end up doing a GFP_KERNEL allocation
                 * in an atomic context.
                 *
                 * Instead, we let the first TLB miss on a hugepage
                 * take care of this.
                 */
        }

        if (!pmd_none(orig)) {
                addr &= HPAGE_MASK;
                if (pmd_trans_huge(orig)) {
                        pte_t orig_pte = __pte(pmd_val(orig));
                        bool exec = pte_exec(orig_pte);

                        tlb_batch_add_one(mm, addr, exec, true);
                        tlb_batch_add_one(mm, addr + REAL_HPAGE_SIZE, exec,
                                        true);
                } else {
                        tlb_batch_pmd_scan(mm, addr, orig);
                }
        }
}

/*
 * This routine is only called when splitting a THP
 */
void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
                     pmd_t *pmdp)
{
        pmd_t entry = *pmdp;

        pmd_val(entry) &= ~_PAGE_VALID;

        set_pmd_at(vma->vm_mm, address, pmdp, entry);
        flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);

        /*
         * set_pmd_at() will not be called in a way to decrement
         * thp_pte_count when splitting a THP, so do it now.
         * Sanity check pmd before doing the actual decrement.
         */
        if ((pmd_val(entry) & _PAGE_PMD_HUGE) &&
            !is_huge_zero_page(pmd_page(entry)))
                (vma->vm_mm)->context.thp_pte_count--;
}

void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
                                pgtable_t pgtable)
{
        struct list_head *lh = (struct list_head *) pgtable;

        assert_spin_locked(&mm->page_table_lock);

        /* FIFO */
        if (!pmd_huge_pte(mm, pmdp))
                INIT_LIST_HEAD(lh);
        else
                list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
        pmd_huge_pte(mm, pmdp) = pgtable;
}

pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
        struct list_head *lh;
        pgtable_t pgtable;

        assert_spin_locked(&mm->page_table_lock);

        /* FIFO */
        pgtable = pmd_huge_pte(mm, pmdp);
        lh = (struct list_head *) pgtable;
        if (list_empty(lh))
                pmd_huge_pte(mm, pmdp) = NULL;
        else {
                pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
                list_del(lh);
        }
        pte_val(pgtable[0]) = 0;
        pte_val(pgtable[1]) = 0;

        return pgtable;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */