/*
   * SPARC64 Huge TLB page support.
   *
   * Copyright (C) 2002, 2003, 2006 David S. Miller (davem@davemloft.net)
   */
  
  #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
   */
  
  static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
  							unsigned long addr,
  							unsigned long len,
  							unsigned long pgoff,
  							unsigned long flags)
  {
  	unsigned long task_size = TASK_SIZE;
  	struct vm_unmapped_area_info info;
  
  	if (test_thread_flag(TIF_32BIT))
  		task_size = STACK_TOP32;
  
  	info.flags = 0;
  	info.length = len;
  	info.low_limit = TASK_UNMAPPED_BASE;
  	info.high_limit = min(task_size, VA_EXCLUDE_START);
  	info.align_mask = PAGE_MASK & ~HPAGE_MASK;
  	info.align_offset = 0;
  	addr = vm_unmapped_area(&info);
  
  	if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
  		VM_BUG_ON(addr != -ENOMEM);
  		info.low_limit = VA_EXCLUDE_END;
  		info.high_limit = task_size;
  		addr = vm_unmapped_area(&info);
  	}
  
  	return addr;
  }
  
  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 mm_struct *mm = current->mm;
  	unsigned long addr = addr0;
  	struct vm_unmapped_area_info info;
  
  	/* This should only ever run for 32-bit processes.  */
  	BUG_ON(!test_thread_flag(TIF_32BIT));
  
  	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
  	info.length = len;
  	info.low_limit = PAGE_SIZE;
  	info.high_limit = mm->mmap_base;
  	info.align_mask = PAGE_MASK & ~HPAGE_MASK;
  	info.align_offset = 0;
  	addr = vm_unmapped_area(&info);
  
  	/*
  	 * 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.
  	 */
  	if (addr & ~PAGE_MASK) {
  		VM_BUG_ON(addr != -ENOMEM);
  		info.flags = 0;
  		info.low_limit = TASK_UNMAPPED_BASE;
  		info.high_limit = STACK_TOP32;
  		addr = vm_unmapped_area(&info);
  	}
  
  	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;
  }