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

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.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)
{
        unsigned long task_size = TASK_SIZE;
        struct vm_unmapped_area_info info;

        if (test_thread_flag(TIF_32BIT))
                task_size = STACK_TOP32;

        info.flags = 0;
        info.length = len;
        info.low_limit = TASK_UNMAPPED_BASE;
        info.high_limit = min(task_size, VA_EXCLUDE_START);
        info.align_mask = PAGE_MASK & ~HPAGE_MASK;
        info.align_offset = 0;
        addr = vm_unmapped_area(&info);

        if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
                VM_BUG_ON(addr != -ENOMEM);
                info.low_limit = VA_EXCLUDE_END;
                info.high_limit = task_size;
                addr = vm_unmapped_area(&info);
        }

        return addr;
}

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 mm_struct *mm = current->mm;
        unsigned long addr = addr0;
        struct vm_unmapped_area_info info;

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

        info.flags = VM_UNMAPPED_AREA_TOPDOWN;
        info.length = len;
        info.low_limit = PAGE_SIZE;
        info.high_limit = mm->mmap_base;
        info.align_mask = PAGE_MASK & ~HPAGE_MASK;
        info.align_offset = 0;
        addr = vm_unmapped_area(&info);

        /*
         * 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.
         */
        if (addr & ~PAGE_MASK) {
                VM_BUG_ON(addr != -ENOMEM);
                info.flags = 0;
                info.low_limit = TASK_UNMAPPED_BASE;
                info.high_limit = STACK_TOP32;
                addr = vm_unmapped_area(&info);
        }

        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, NULL, 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;
}

int pmd_huge_support(void)
{
        return 0;
}

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