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/*

 * 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);

        pmd = pmd_offset(pgd, taddr);

        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_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,

};