/*
 * SPARC64 Huge TLB page support.
 *
 * Copyright (C) 2002, 2003, 2006 David S. Miller (davem@davemloft.net)
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/sysctl.h>

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

/* Slightly simplified from the non-hugepage variant because by
 * definition we don't have to worry about any page coloring stuff
 */
#define VA_EXCLUDE_START (0x0000080000000000UL - (1UL << 32UL))
#define VA_EXCLUDE_END   (0xfffff80000000000UL + (1UL << 32UL))

static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
                                                        unsigned long addr,
                                                        unsigned long len,
                                                        unsigned long pgoff,
                                                        unsigned long flags)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct * vma;
        unsigned long task_size = TASK_SIZE;
        unsigned long start_addr;

        if (test_thread_flag(TIF_32BIT))
                task_size = STACK_TOP32;
        if (unlikely(len >= VA_EXCLUDE_START))
                return -ENOMEM;

        if (len > mm->cached_hole_size) {
                start_addr = addr = mm->free_area_cache;
        } else {
                start_addr = addr = TASK_UNMAPPED_BASE;
                mm->cached_hole_size = 0;
        }

        task_size -= len;

full_search:
        addr = ALIGN(addr, HPAGE_SIZE);

        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
                /* At this point:  (!vma || addr < vma->vm_end). */
                if (addr < VA_EXCLUDE_START &&
                    (addr + len) >= VA_EXCLUDE_START) {
                        addr = VA_EXCLUDE_END;
                        vma = find_vma(mm, VA_EXCLUDE_END);
                }
                if (unlikely(task_size < addr)) {
                        if (start_addr != TASK_UNMAPPED_BASE) {
                                start_addr = addr = TASK_UNMAPPED_BASE;
                                mm->cached_hole_size = 0;
                                goto full_search;
                        }
                        return -ENOMEM;
                }
                if (likely(!vma || addr + len <= vma->vm_start)) {
                        /*
                         * Remember the place where we stopped the search:
                         */
                        mm->free_area_cache = addr + len;
                        return addr;
                }
                if (addr + mm->cached_hole_size < vma->vm_start)
                        mm->cached_hole_size = vma->vm_start - addr;

                addr = ALIGN(vma->vm_end, HPAGE_SIZE);
        }
}

static unsigned long
hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                                  const unsigned long len,
                                  const unsigned long pgoff,
                                  const unsigned long flags)
{
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
        unsigned long addr = addr0;

        /* This should only ever run for 32-bit processes.  */
        BUG_ON(!test_thread_flag(TIF_32BIT));

        /* check if free_area_cache is useful for us */
        if (len <= mm->cached_hole_size) {
                mm->cached_hole_size = 0;
                mm->free_area_cache = mm->mmap_base;
        }

        /* either no address requested or can't fit in requested address hole */
        addr = mm->free_area_cache & HPAGE_MASK;

        /* make sure it can fit in the remaining address space */
        if (likely(addr > len)) {
                vma = find_vma(mm, addr-len);
                if (!vma || addr <= vma->vm_start) {
                        /* remember the address as a hint for next time */
                        return (mm->free_area_cache = addr-len);
                }
        }

        if (unlikely(mm->mmap_base < len))
                goto bottomup;

        addr = (mm->mmap_base-len) & HPAGE_MASK;

        do {
                /*
                 * Lookup failure means no vma is above this address,
                 * else if new region fits below vma->vm_start,
                 * return with success:
                 */
                vma = find_vma(mm, addr);
                if (likely(!vma || addr+len <= vma->vm_start)) {
                        /* remember the address as a hint for next time */
                        return (mm->free_area_cache = addr);
                }

                /* remember the largest hole we saw so far */
                if (addr + mm->cached_hole_size < vma->vm_start)
                        mm->cached_hole_size = vma->vm_start - addr;

                /* try just below the current vma->vm_start */
                addr = (vma->vm_start-len) & HPAGE_MASK;
        } while (likely(len < vma->vm_start));

bottomup:
        /*
         * A failed mmap() very likely causes application failure,
         * so fall back to the bottom-up function here. This scenario
         * can happen with large stack limits and large mmap()
         * allocations.
         */
        mm->cached_hole_size = ~0UL;
        mm->free_area_cache = TASK_UNMAPPED_BASE;
        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
        /*
         * Restore the topdown base:
         */
        mm->free_area_cache = mm->mmap_base;
        mm->cached_hole_size = ~0UL;

        return addr;
}

unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
                unsigned long len, unsigned long pgoff, unsigned long flags)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        unsigned long task_size = TASK_SIZE;

        if (test_thread_flag(TIF_32BIT))
                task_size = STACK_TOP32;

        if (len & ~HPAGE_MASK)
                return -EINVAL;
        if (len > task_size)
                return -ENOMEM;

        if (flags & MAP_FIXED) {
                if (prepare_hugepage_range(file, addr, len))
                        return -EINVAL;
                return addr;
        }

        if (addr) {
                addr = ALIGN(addr, HPAGE_SIZE);
                vma = find_vma(mm, addr);
                if (task_size - len >= addr &&
                    (!vma || addr + len <= vma->vm_start))
                        return addr;
        }
        if (mm->get_unmapped_area == arch_get_unmapped_area)
                return hugetlb_get_unmapped_area_bottomup(file, addr, len,
                                pgoff, flags);
        else
                return hugetlb_get_unmapped_area_topdown(file, addr, len,
                                pgoff, flags);
}

pte_t *huge_pte_alloc(struct mm_struct *mm,
                        unsigned long addr, unsigned long sz)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte = NULL;

        /* We must align the address, because our caller will run
         * set_huge_pte_at() on whatever we return, which writes out
         * all of the sub-ptes for the hugepage range.  So we have
         * to give it the first such sub-pte.
         */
        addr &= HPAGE_MASK;

        pgd = pgd_offset(mm, addr);
        pud = pud_alloc(mm, pgd, addr);
        if (pud) {
                pmd = pmd_alloc(mm, pud, addr);
                if (pmd)
                        pte = pte_alloc_map(mm, pmd, addr);
        }
        return pte;
}

pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte = NULL;

        addr &= HPAGE_MASK;

        pgd = pgd_offset(mm, addr);
        if (!pgd_none(*pgd)) {
                pud = pud_offset(pgd, addr);
                if (!pud_none(*pud)) {
                        pmd = pmd_offset(pud, addr);
                        if (!pmd_none(*pmd))
                                pte = pte_offset_map(pmd, addr);
                }
        }
        return pte;
}

int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
        return 0;
}

void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
                     pte_t *ptep, pte_t entry)
{
        int i;

        if (!pte_present(*ptep) && pte_present(entry))
                mm->context.huge_pte_count++;

        addr &= HPAGE_MASK;
        for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
                set_pte_at(mm, addr, ptep, entry);
                ptep++;
                addr += PAGE_SIZE;
                pte_val(entry) += PAGE_SIZE;
        }
}

pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
                              pte_t *ptep)
{
        pte_t entry;
        int i;

        entry = *ptep;
        if (pte_present(entry))
                mm->context.huge_pte_count--;

        addr &= HPAGE_MASK;

        for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
                pte_clear(mm, addr, ptep);
                addr += PAGE_SIZE;
                ptep++;
        }

        return entry;
}

struct page *follow_huge_addr(struct mm_struct *mm,
                              unsigned long address, int write)
{
        return ERR_PTR(-EINVAL);
}

int pmd_huge(pmd_t pmd)
{
        return 0;
}

int pud_huge(pud_t pud)
{
        return 0;
}

struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
                             pmd_t *pmd, int write)
{
        return NULL;
}

static void context_reload(void *__data)
{
        struct mm_struct *mm = __data;

        if (mm == current->mm)
                load_secondary_context(mm);
}

void hugetlb_prefault_arch_hook(struct mm_struct *mm)
{
        struct tsb_config *tp = &mm->context.tsb_block[MM_TSB_HUGE];

        if (likely(tp->tsb != NULL))
                return;

        tsb_grow(mm, MM_TSB_HUGE, 0);
        tsb_context_switch(mm);
        smp_tsb_sync(mm);

        /* On UltraSPARC-III+ and later, configure the second half of
         * the Data-TLB for huge pages.
         */
        if (tlb_type == cheetah_plus) {
                unsigned long ctx;

                spin_lock(&ctx_alloc_lock);
                ctx = mm->context.sparc64_ctx_val;
                ctx &= ~CTX_PGSZ_MASK;
                ctx |= CTX_PGSZ_BASE << CTX_PGSZ0_SHIFT;
                ctx |= CTX_PGSZ_HUGE << CTX_PGSZ1_SHIFT;

                if (ctx != mm->context.sparc64_ctx_val) {
                        /* When changing the page size fields, we
                         * must perform a context flush so that no
                         * stale entries match.  This flush must
                         * occur with the original context register
                         * settings.
                         */
                        do_flush_tlb_mm(mm);

                        /* Reload the context register of all processors
                         * also executing in this address space.
                         */
                        mm->context.sparc64_ctx_val = ctx;
                        on_each_cpu(context_reload, mm, 0);
                }
                spin_unlock(&ctx_alloc_lock);
        }
}