hugetlbpage.c

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/*
 * SPARC64 Huge TLB page support.
 *
 * Copyright (C) 2002, 2003, 2006 David S. Miller ([email protected])
 */

#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)
{
    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, 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;
}

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