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hugetlbpage.c

/*
 * IA-64 Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2002-2004 Rohit Seth <rohit.seth@intel.com>
 * Copyright (C) 2003-2004 Ken Chen <kenneth.w.chen@intel.com>
 *
 * 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/slab.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, 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);

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