/*
   * 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/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_unmapped_area_info info;
  
  	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;
  
  	info.flags = 0;
  	info.length = len;
  	info.low_limit = addr;
  	info.high_limit = HPAGE_REGION_BASE + RGN_MAP_LIMIT;
  	info.align_mask = PAGE_MASK & (HPAGE_SIZE - 1);
  	info.align_offset = 0;
  	return vm_unmapped_area(&info);
  }
  
  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
  ");
  		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);