arch/i386/mm/hugetlbpage.c

   1 /*
   2  * IA-32 Huge TLB Page Support for Kernel.
   3  *
   4  * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
   5  */
   6
   7 #include <linux/config.h>
   8 #include <linux/init.h>
   9 #include <linux/fs.h>
  10 #include <linux/mm.h>
  11 #include <linux/hugetlb.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/smp_lock.h>
  14 #include <linux/slab.h>
  15 #include <linux/err.h>
  16 #include <linux/sysctl.h>
  17 #include <asm/mman.h>
  18 #include <asm/tlb.h>
  19 #include <asm/tlbflush.h>
  20
  21 pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
  22 {
  23         pgd_t *pgd;
  24         pud_t *pud;
  25         pte_t *pte = NULL;
  26
  27         pgd = pgd_offset(mm, addr);
  28         pud = pud_alloc(mm, pgd, addr);
  29         if (pud)
  30                 pte = (pte_t *) pmd_alloc(mm, pud, addr);
  31         BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
  32
  33         return pte;
  34 }
  35
  36 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
  37 {
  38         pgd_t *pgd;
  39         pud_t *pud;
  40         pmd_t *pmd = NULL;
  41
  42         pgd = pgd_offset(mm, addr);
  43         if (pgd_present(*pgd)) {
  44                 pud = pud_offset(pgd, addr);
  45                 if (pud_present(*pud))
  46                         pmd = pmd_offset(pud, addr);
  47         }
  48         return (pte_t *) pmd;
  49 }
  50
  51 /*
  52  * This function checks for proper alignment of input addr and len parameters.
  53  */
  54 int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
  55 {
  56         if (len & ~HPAGE_MASK)
  57                 return -EINVAL;
  58         if (addr & ~HPAGE_MASK)
  59                 return -EINVAL;
  60         return 0;
  61 }
  62
  63 #if 0   /* This is just for testing */
  64 struct page *
  65 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
  66 {
  67         unsigned long start = address;
  68         int length = 1;
  69         int nr;
  70         struct page *page;
  71         struct vm_area_struct *vma;
  72
  73         vma = find_vma(mm, addr);
  74         if (!vma || !is_vm_hugetlb_page(vma))
  75                 return ERR_PTR(-EINVAL);
  76
  77         pte = huge_pte_offset(mm, address);
  78
  79         /* hugetlb should be locked, and hence, prefaulted */
  80         WARN_ON(!pte || pte_none(*pte));
  81
  82         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
  83
  84         WARN_ON(!PageCompound(page));
  85
  86         return page;
  87 }
  88
  89 int pmd_huge(pmd_t pmd)
  90 {
  91         return 0;
  92 }
  93
  94 struct page *
  95 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
  96                 pmd_t *pmd, int write)
  97 {
  98         return NULL;
  99 }
 100
 101 #else
 102
 103 struct page *
 104 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 105 {
 106         return ERR_PTR(-EINVAL);
 107 }
 108
 109 int pmd_huge(pmd_t pmd)
 110 {
 111         return !!(pmd_val(pmd) & _PAGE_PSE);
 112 }
 113
 114 struct page *
 115 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 116                 pmd_t *pmd, int write)
 117 {
 118         struct page *page;
 119
 120         page = pte_page(*(pte_t *)pmd);
 121         if (page)
 122                 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
 123         return page;
 124 }
 125 #endif
 126
 127 /* x86_64 also uses this file */
 128
 129 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 130 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 131                 unsigned long addr, unsigned long len,
 132                 unsigned long pgoff, unsigned long flags)
 133 {
 134         struct mm_struct *mm = current->mm;
 135         struct vm_area_struct *vma;
 136         unsigned long start_addr;
 137
 138         if (len > mm->cached_hole_size) {
 139                 start_addr = mm->free_area_cache;
 140         } else {
 141                 start_addr = TASK_UNMAPPED_BASE;
 142                 mm->cached_hole_size = 0;
 143         }
 144
 145 full_search:
 146         addr = ALIGN(start_addr, HPAGE_SIZE);
 147
 148         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 149                 /* At this point:  (!vma || addr < vma->vm_end). */
 150                 if (TASK_SIZE - len < addr) {
 151                         /*
 152                          * Start a new search - just in case we missed
 153                          * some holes.
 154                          */
 155                         if (start_addr != TASK_UNMAPPED_BASE) {
 156                                 start_addr = TASK_UNMAPPED_BASE;
 157                                 mm->cached_hole_size = 0;
 158                                 goto full_search;
 159                         }
 160                         return -ENOMEM;
 161                 }
 162                 if (!vma || addr + len <= vma->vm_start) {
 163                         mm->free_area_cache = addr + len;
 164                         return addr;
 165                 }
 166                 if (addr + mm->cached_hole_size < vma->vm_start)
 167                         mm->cached_hole_size = vma->vm_start - addr;
 168                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 169         }
 170 }
 171
 172 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 173                 unsigned long addr0, unsigned long len,
 174                 unsigned long pgoff, unsigned long flags)
 175 {
 176         struct mm_struct *mm = current->mm;
 177         struct vm_area_struct *vma, *prev_vma;
 178         unsigned long base = mm->mmap_base, addr = addr0;
 179         unsigned long largest_hole = mm->cached_hole_size;
 180         int first_time = 1;
 181
 182         /* don't allow allocations above current base */
 183         if (mm->free_area_cache > base)
 184                 mm->free_area_cache = base;
 185
 186         if (len <= largest_hole) {
 187                 largest_hole = 0;
 188                 mm->free_area_cache  = base;
 189         }
 190 try_again:
 191         /* make sure it can fit in the remaining address space */
 192         if (mm->free_area_cache < len)
 193                 goto fail;
 194
 195         /* either no address requested or cant fit in requested address hole */
 196         addr = (mm->free_area_cache - len) & HPAGE_MASK;
 197         do {
 198                 /*
 199                  * Lookup failure means no vma is above this address,
 200                  * i.e. return with success:
 201                  */
 202                 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
 203                         return addr;
 204
 205                 /*
 206                  * new region fits between prev_vma->vm_end and
 207                  * vma->vm_start, use it:
 208                  */
 209                 if (addr + len <= vma->vm_start &&
 210                             (!prev_vma || (addr >= prev_vma->vm_end))) {
 211                         /* remember the address as a hint for next time */
 212                         mm->cached_hole_size = largest_hole;
 213                         return (mm->free_area_cache = addr);
 214                 } else {
 215                         /* pull free_area_cache down to the first hole */
 216                         if (mm->free_area_cache == vma->vm_end) {
 217                                 mm->free_area_cache = vma->vm_start;
 218                                 mm->cached_hole_size = largest_hole;
 219                         }
 220                 }
 221
 222                 /* remember the largest hole we saw so far */
 223                 if (addr + largest_hole < vma->vm_start)
 224                         largest_hole = vma->vm_start - addr;
 225
 226                 /* try just below the current vma->vm_start */
 227                 addr = (vma->vm_start - len) & HPAGE_MASK;
 228         } while (len <= vma->vm_start);
 229
 230 fail:
 231         /*
 232          * if hint left us with no space for the requested
 233          * mapping then try again:
 234          */
 235         if (first_time) {
 236                 mm->free_area_cache = base;
 237                 largest_hole = 0;
 238                 first_time = 0;
 239                 goto try_again;
 240         }
 241         /*
 242          * A failed mmap() very likely causes application failure,
 243          * so fall back to the bottom-up function here. This scenario
 244          * can happen with large stack limits and large mmap()
 245          * allocations.
 246          */
 247         mm->free_area_cache = TASK_UNMAPPED_BASE;
 248         mm->cached_hole_size = ~0UL;
 249         addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
 250                         len, pgoff, flags);
 251
 252         /*
 253          * Restore the topdown base:
 254          */
 255         mm->free_area_cache = base;
 256         mm->cached_hole_size = ~0UL;
 257
 258         return addr;
 259 }
 260
 261 unsigned long
 262 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 263                 unsigned long len, unsigned long pgoff, unsigned long flags)
 264 {
 265         struct mm_struct *mm = current->mm;
 266         struct vm_area_struct *vma;
 267
 268         if (len & ~HPAGE_MASK)
 269                 return -EINVAL;
 270         if (len > TASK_SIZE)
 271                 return -ENOMEM;
 272
 273         if (addr) {
 274                 addr = ALIGN(addr, HPAGE_SIZE);
 275                 vma = find_vma(mm, addr);
 276                 if (TASK_SIZE - len >= addr &&
 277                     (!vma || addr + len <= vma->vm_start))
 278                         return addr;
 279         }
 280         if (mm->get_unmapped_area == arch_get_unmapped_area)
 281                 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
 282                                 pgoff, flags);
 283         else
 284                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
 285                                 pgoff, flags);
 286 }
 287
 288 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
 289