/*
 * IA-64 Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
 */

#include <linux/config.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <asm/mman.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>


#define TASK_HPAGE_BASE (REGION_HPAGE << REGION_SHIFT)

static long    htlbpagemem;
int     htlbpage_max;
static long    htlbzone_pages;

struct vm_operations_struct hugetlb_vm_ops;
static LIST_HEAD(htlbpage_freelist);
static spinlock_t htlbpage_lock = SPIN_LOCK_UNLOCKED;

static struct page *alloc_hugetlb_page(void)
{
        int i;
        struct page *page;

        spin_lock(&htlbpage_lock);
        if (list_empty(&htlbpage_freelist)) {
                spin_unlock(&htlbpage_lock);
                return NULL;
        }

        page = list_entry(htlbpage_freelist.next, struct page, list);
        list_del(&page->list);
        htlbpagemem--;
        spin_unlock(&htlbpage_lock);
        set_page_count(page, 1);
        for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
                clear_highpage(&page[i]);
        return page;
}

static pte_t *
huge_pte_alloc (struct mm_struct *mm, unsigned long addr)
{
        unsigned long taddr = htlbpage_to_page(addr);
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *pte = NULL;

        pgd = pgd_offset(mm, taddr);
        pmd = pmd_alloc(mm, pgd, taddr);
        if (pmd)
                pte = pte_alloc(mm, pmd, taddr);
        return pte;
}

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

        pgd = pgd_offset(mm, taddr);
        if (pgd_present(*pgd)) {
                pmd = pmd_offset(pgd, taddr);
                if (pmd_present(*pmd))
                        pte = pte_offset(pmd, taddr);
        }

        return pte;
}

#define mk_pte_huge(entry) { pte_val(entry) |= _PAGE_P; }

static void
set_huge_pte (struct mm_struct *mm, struct vm_area_struct *vma,
              struct page *page, pte_t * page_table, int write_access)
{
        pte_t entry;

        mm->rss += (HPAGE_SIZE / PAGE_SIZE);
        if (write_access) {
                entry =
                    pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
        } else
                entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
        entry = pte_mkyoung(entry);
        mk_pte_huge(entry);
        set_pte(page_table, entry);
        return;
}
/*
 * This function checks for proper alignment of input addr and len parameters.
 */
int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
{
        if (len & ~HPAGE_MASK)
                return -EINVAL;
        if (addr & ~HPAGE_MASK)
                return -EINVAL;
        if (REGION_NUMBER(addr) != REGION_HPAGE)
                return -EINVAL;

        return 0;
}
/* This function checks if the address and address+len falls out of HugeTLB region.  It
 * return -EINVAL if any part of address range falls in HugeTLB region.
 */
int  is_invalid_hugepage_range(unsigned long addr, unsigned long len)
{
        if (REGION_NUMBER(addr) == REGION_HPAGE)
                return -EINVAL;
        if (REGION_NUMBER(addr+len) == REGION_HPAGE)
                return -EINVAL;
        return 0;
}

/*
 * Same as generic free_pgtables(), except constant PGDIR_* and pgd_offset
 * are hugetlb region specific.
 */
void hugetlb_free_pgtables(struct mm_struct * mm, struct vm_area_struct *prev,
        unsigned long start, unsigned long end)
{
        unsigned long first = start & HUGETLB_PGDIR_MASK;
        unsigned long last = end + HUGETLB_PGDIR_SIZE - 1;
        unsigned long start_index, end_index;

        if (!prev) {
                prev = mm->mmap;
                if (!prev)
                        goto no_mmaps;
                if (prev->vm_end > start) {
                        if (last > prev->vm_start)
                                last = prev->vm_start;
                        goto no_mmaps;
                }
        }
        for (;;) {
                struct vm_area_struct *next = prev->vm_next;

                if (next) {
                        if (next->vm_start < start) {
                                prev = next;
                                continue;
                        }
                        if (last > next->vm_start)
                                last = next->vm_start;
                }
                if (prev->vm_end > first)
                        first = prev->vm_end + HUGETLB_PGDIR_SIZE - 1;
                break;
        }
no_mmaps:
        if (last < first)
                return;
        /*
         * If the PGD bits are not consecutive in the virtual address, the
         * old method of shifting the VA >> by PGDIR_SHIFT doesn't work.
         */
        start_index = pgd_index(htlbpage_to_page(first));
        end_index = pgd_index(htlbpage_to_page(last));
        if (end_index > start_index) {
                clear_page_tables(mm, start_index, end_index - start_index);
                flush_tlb_pgtables(mm, first & HUGETLB_PGDIR_MASK,
                                   last & HUGETLB_PGDIR_MASK);
        }
}

int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
                        struct vm_area_struct *vma)
{
        pte_t *src_pte, *dst_pte, entry;
        struct page *ptepage;
        unsigned long addr = vma->vm_start;
        unsigned long end = vma->vm_end;

        while (addr < end) {
                dst_pte = huge_pte_alloc(dst, addr);
                if (!dst_pte)
                        goto nomem;
                src_pte = huge_pte_offset(src, addr);
                entry = *src_pte;
                ptepage = pte_page(entry);
                get_page(ptepage);
                set_pte(dst_pte, entry);
                dst->rss += (HPAGE_SIZE / PAGE_SIZE);
                addr += HPAGE_SIZE;
        }
        return 0;
nomem:
        return -ENOMEM;
}

int
follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
                    struct page **pages, struct vm_area_struct **vmas,
                    unsigned long *st, int *length, int i)
{
        pte_t *ptep, pte;
        unsigned long start = *st;
        unsigned long pstart;
        int len = *length;
        struct page *page;

        do {
                pstart = start;
                ptep = huge_pte_offset(mm, start);
                pte = *ptep;

back1:
                page = pte_page(pte);
                if (pages) {
                        page += ((start & ~HPAGE_MASK) >> PAGE_SHIFT);
                        pages[i] = page;
                }
                if (vmas)
                        vmas[i] = vma;
                i++;
                len--;
                start += PAGE_SIZE;
                if (((start & HPAGE_MASK) == pstart) && len &&
                                (start < vma->vm_end))
                        goto back1;
        } while (len && start < vma->vm_end);
        *length = len;
        *st = start;
        return i;
}

void free_huge_page(struct page *page)
{
        BUG_ON(page_count(page));
        BUG_ON(page->mapping);

        INIT_LIST_HEAD(&page->list);

        spin_lock(&htlbpage_lock);
        list_add(&page->list, &htlbpage_freelist);
        htlbpagemem++;
        spin_unlock(&htlbpage_lock);
}

void huge_page_release(struct page *page)
{
        if (!put_page_testzero(page))
                return;

        free_huge_page(page);
}

void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, unsigned long end)
{
        struct mm_struct *mm = vma->vm_mm;
        unsigned long address;
        pte_t *pte;
        struct page *page;

        BUG_ON(start & (HPAGE_SIZE - 1));
        BUG_ON(end & (HPAGE_SIZE - 1));

        for (address = start; address < end; address += HPAGE_SIZE) {
                pte = huge_pte_offset(mm, address);
                if (!pte || pte_none(*pte))
                        continue;
                page = pte_page(*pte);
                huge_page_release(page);
                pte_clear(pte);
        }
        mm->rss -= (end - start) >> PAGE_SHIFT;
        flush_tlb_range(mm, start, end);
}

void zap_hugepage_range(struct vm_area_struct *vma, unsigned long start, unsigned long length)
{
        struct mm_struct *mm = vma->vm_mm;
        spin_lock(&mm->page_table_lock);
        unmap_hugepage_range(vma, start, start + length);
        spin_unlock(&mm->page_table_lock);
}

int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
{
        struct mm_struct *mm = current->mm;
        struct inode *inode = mapping->host;
        unsigned long addr;
        int ret = 0;

        BUG_ON(vma->vm_start & ~HPAGE_MASK);
        BUG_ON(vma->vm_end & ~HPAGE_MASK);

        spin_lock(&mm->page_table_lock);
        for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
                unsigned long idx;
                pte_t *pte = huge_pte_alloc(mm, addr);
                struct page *page;

                if (!pte) {
                        ret = -ENOMEM;
                        goto out;
                }
                if (!pte_none(*pte))
                        continue;

                idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
                        + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
                page = find_get_page(mapping, idx);
                if (!page) {
                        /* charge the fs quota first */
                        if (hugetlb_get_quota(mapping)) {
                                ret = -ENOMEM;
                                goto out;
                        }
                        page = alloc_hugetlb_page();
                        if (!page) {
                                hugetlb_put_quota(mapping);
                                ret = -ENOMEM;
                                goto out;
                        }
                        add_to_page_cache(page, mapping, idx);
                        unlock_page(page);
                }
                set_huge_pte(mm, vma, page, pte, vma->vm_flags & VM_WRITE);
        }
out:
        spin_unlock(&mm->page_table_lock);
        return ret;
}

unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
                unsigned long pgoff, unsigned long flags)
{
        struct vm_area_struct *vmm;

        if (len > RGN_MAP_LIMIT)
                return -ENOMEM;
        if (len & ~HPAGE_MASK)
                return -EINVAL;
        /* This code assumes that REGION_HPAGE != 0. */
        if ((REGION_NUMBER(addr) != REGION_HPAGE) || (addr & (HPAGE_SIZE - 1)))
                addr = TASK_HPAGE_BASE;
        else
                addr = COLOR_HALIGN(addr);
        for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
                /* At this point:  (!vmm || addr < vmm->vm_end). */
                if (REGION_OFFSET(addr) + len > RGN_MAP_LIMIT)
                        return -ENOMEM;
                if (!vmm || (addr + len) <= vmm->vm_start)
                        return addr;
                addr = COLOR_HALIGN(vmm->vm_end);
        }
}
void update_and_free_page(struct page *page)
{
        int j;
        struct page *map;

        map = page;
        htlbzone_pages--;
        for (j = 0; j < (HPAGE_SIZE / PAGE_SIZE); j++) {
                map->flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
                                1 << PG_dirty | 1 << PG_active | 1 << PG_reserved);
                set_page_count(map, 0);
                map++;
        }
        set_page_count(page, 1);
        __free_pages(page, HUGETLB_PAGE_ORDER);
}

int try_to_free_low(int count)
{
        struct list_head *p;
        struct page *page, *map;

        map = NULL;
        spin_lock(&htlbpage_lock);
        list_for_each(p, &htlbpage_freelist) {
                if (map) {
                        list_del(&map->list);
                        update_and_free_page(map);
                        htlbpagemem--;
                        map = NULL;
                        if (++count == 0)
                                break;
                }
                page = list_entry(p, struct page, list);
                if ((page_zone(page))->name[0] != 'H') //Look for non-Highmem zones.
                        map = page;
        }
        if (map) {
                list_del(&map->list);
                update_and_free_page(map);
                htlbpagemem--;
                count++;
        }
        spin_unlock(&htlbpage_lock);
        return count;
}

int set_hugetlb_mem_size(int count)
{
        int j, lcount;
        struct page *page, *map;

        if (count < 0)
                lcount = count;
        else
                lcount = count - htlbzone_pages;

        if (lcount == 0)
                return (int)htlbzone_pages;
        if (lcount > 0) {       /* Increase the mem size. */
                while (lcount--) {
                        page = alloc_pages(__GFP_HIGHMEM, HUGETLB_PAGE_ORDER);
                        if (page == NULL)
                                break;
                        map = page;
                        for (j = 0; j < (HPAGE_SIZE / PAGE_SIZE); j++) {
                                SetPageReserved(map);
                                map++;
                        }
                        spin_lock(&htlbpage_lock);
                        list_add(&page->list, &htlbpage_freelist);
                        htlbpagemem++;
                        htlbzone_pages++;
                        spin_unlock(&htlbpage_lock);
                }
                return (int) htlbzone_pages;
        }
        /* Shrink the memory size. */
        lcount = try_to_free_low(lcount);
        while (lcount++ < 0) {
                page = alloc_hugetlb_page();
                if (page == NULL)
                        break;
                spin_lock(&htlbpage_lock);
                update_and_free_page(page);
                spin_unlock(&htlbpage_lock);
        }
        return (int) htlbzone_pages;
}

int hugetlb_sysctl_handler(ctl_table *table, int write, struct file *file, void *buffer, size_t *length)
{
        proc_dointvec(table, write, file, buffer, length);
        htlbpage_max = set_hugetlb_mem_size(htlbpage_max);
        return 0;
}

static int __init hugetlb_setup(char *s)
{
        if (sscanf(s, "%d", &htlbpage_max) <= 0)
                htlbpage_max = 0;
        return 1;
}
__setup("hugepages=", hugetlb_setup);

static int __init hugetlb_init(void)
{
        int i, j;
        struct page *page;

        for (i = 0; i < htlbpage_max; ++i) {
                page = alloc_pages(__GFP_HIGHMEM, HUGETLB_PAGE_ORDER);
                if (!page)
                        break;
                for (j = 0; j < HPAGE_SIZE/PAGE_SIZE; ++j)
                        SetPageReserved(&page[j]);
                spin_lock(&htlbpage_lock);
                list_add(&page->list, &htlbpage_freelist);
                spin_unlock(&htlbpage_lock);
        }
        htlbpage_max = htlbpagemem = htlbzone_pages = i;
        printk("Total HugeTLB memory allocated, %ld\n", htlbpagemem);
        return 0;
}
module_init(hugetlb_init);

int hugetlb_report_meminfo(char *buf)
{
        return sprintf(buf,
                        "HugePages_Total: %5lu\n"
                        "HugePages_Free:  %5lu\n"
                        "Hugepagesize:    %5lu kB\n",
                        htlbzone_pages,
                        htlbpagemem,
                        HPAGE_SIZE/1024);
}

int is_hugepage_mem_enough(size_t size)
{
        if (size > (htlbpagemem << HPAGE_SHIFT))
                return 0;
        return 1;
}

static struct page *hugetlb_nopage(struct vm_area_struct * area, unsigned long address, int unused)
{
        BUG();
        return NULL;
}

struct vm_operations_struct hugetlb_vm_ops = {
        .nopage =       hugetlb_nopage,
};