hugetlbpage.c

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/*
 * IA-64 Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2002-2004 Rohit Seth <[email protected]>
 * Copyright (C) 2003-2004 Ken Chen <[email protected]>
 *
 * Sep, 2003: add numa support
 * Feb, 2004: dynamic hugetlb page size via boot parameter
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/log2.h>
#include <asm/mman.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>

unsigned int hpage_shift = HPAGE_SHIFT_DEFAULT;
EXPORT_SYMBOL(hpage_shift);

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

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

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

    pgd = pgd_offset(mm, taddr);
    if (pgd_present(*pgd)) {
        pud = pud_offset(pgd, taddr);
        if (pud_present(*pud)) {
            pmd = pmd_offset(pud, taddr);
            if (pmd_present(*pmd))
                pte = pte_offset_map(pmd, taddr);
        }
    }

    return pte;
}

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

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

/*
 * Don't actually need to do any preparation, but need to make sure
 * the address is in the right region.
 */
int prepare_hugepage_range(struct file *file,
            unsigned long addr, unsigned long len)
{
    if (len & ~HPAGE_MASK)
        return -EINVAL;
    if (addr & ~HPAGE_MASK)
        return -EINVAL;
    if (REGION_NUMBER(addr) != RGN_HPAGE)
        return -EINVAL;

    return 0;
}

struct page *follow_huge_addr(struct mm_struct *mm, unsigned long addr, int write)
{
    struct page *page;
    pte_t *ptep;

    if (REGION_NUMBER(addr) != RGN_HPAGE)
        return ERR_PTR(-EINVAL);

    ptep = huge_pte_offset(mm, addr);
    if (!ptep || pte_none(*ptep))
        return NULL;
    page = pte_page(*ptep);
    page += ((addr & ~HPAGE_MASK) >> PAGE_SHIFT);
    return page;
}
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;
}

void hugetlb_free_pgd_range(struct mmu_gather *tlb,
            unsigned long addr, unsigned long end,
            unsigned long floor, unsigned long ceiling)
{
    /*
     * This is called to free hugetlb page tables.
     *
     * The offset of these addresses from the base of the hugetlb
     * region must be scaled down by HPAGE_SIZE/PAGE_SIZE so that
     * the standard free_pgd_range will free the right page tables.
     *
     * If floor and ceiling are also in the hugetlb region, they
     * must likewise be scaled down; but if outside, left unchanged.
     */

    addr = htlbpage_to_page(addr);
    end  = htlbpage_to_page(end);
    if (REGION_NUMBER(floor) == RGN_HPAGE)
        floor = htlbpage_to_page(floor);
    if (REGION_NUMBER(ceiling) == RGN_HPAGE)
        ceiling = htlbpage_to_page(ceiling);

    free_pgd_range(tlb, addr, end, floor, ceiling);
}

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;

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

    /* This code assumes that RGN_HPAGE != 0. */
    if ((REGION_NUMBER(addr) != RGN_HPAGE) || (addr & (HPAGE_SIZE - 1)))
        addr = HPAGE_REGION_BASE;
    else
        addr = ALIGN(addr, HPAGE_SIZE);
    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 = ALIGN(vmm->vm_end, HPAGE_SIZE);
    }
}

static int __init hugetlb_setup_sz(char *str)
{
    u64 tr_pages;
    unsigned long long size;

    if (ia64_pal_vm_page_size(&tr_pages, NULL) != 0)
        /*
         * shouldn't happen, but just in case.
         */
        tr_pages = 0x15557000UL;

    size = memparse(str, &str);
    if (*str || !is_power_of_2(size) || !(tr_pages & size) ||
        size <= PAGE_SIZE ||
        size >= (1UL << PAGE_SHIFT << MAX_ORDER)) {
        printk(KERN_WARNING "Invalid huge page size specified\n");
        return 1;
    }

    hpage_shift = __ffs(size);
    /*
     * boot cpu already executed ia64_mmu_init, and has HPAGE_SHIFT_DEFAULT
     * override here with new page shift.
     */
    ia64_set_rr(HPAGE_REGION_BASE, hpage_shift << 2);
    return 0;
}
early_param("hugepagesz", hugetlb_setup_sz);