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         pmd_t *pmd = NULL;
  26
  27         pgd = pgd_offset(mm, addr);
  28         pud = pud_alloc(mm, pgd, addr);
  29         pmd = pmd_alloc(mm, pud, addr);
  30         return (pte_t *) pmd;
  31 }
  32
  33 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
  34 {
  35         pgd_t *pgd;
  36         pud_t *pud;
  37         pmd_t *pmd = NULL;
  38
  39         pgd = pgd_offset(mm, addr);
  40         pud = pud_offset(pgd, addr);
  41         pmd = pmd_offset(pud, addr);
  42         return (pte_t *) pmd;
  43 }
  44
  45 /*
  46  * This function checks for proper alignment of input addr and len parameters.
  47  */
  48 int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
  49 {
  50         if (len & ~HPAGE_MASK)
  51                 return -EINVAL;
  52         if (addr & ~HPAGE_MASK)
  53                 return -EINVAL;
  54         return 0;
  55 }
  56
  57 #if 0   /* This is just for testing */
  58 struct page *
  59 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
  60 {
  61         unsigned long start = address;
  62         int length = 1;
  63         int nr;
  64         struct page *page;
  65         struct vm_area_struct *vma;
  66
  67         vma = find_vma(mm, addr);
  68         if (!vma || !is_vm_hugetlb_page(vma))
  69                 return ERR_PTR(-EINVAL);
  70
  71         pte = huge_pte_offset(mm, address);
  72
  73         /* hugetlb should be locked, and hence, prefaulted */
  74         WARN_ON(!pte || pte_none(*pte));
  75
  76         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
  77
  78         WARN_ON(!PageCompound(page));
  79
  80         return page;
  81 }
  82
  83 int pmd_huge(pmd_t pmd)
  84 {
  85         return 0;
  86 }
  87
  88 struct page *
  89 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
  90                 pmd_t *pmd, int write)
  91 {
  92         return NULL;
  93 }
  94
  95 #else
  96
  97 struct page *
  98 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
  99 {
 100         return ERR_PTR(-EINVAL);
 101 }
 102
 103 int pmd_huge(pmd_t pmd)
 104 {
 105         return !!(pmd_val(pmd) & _PAGE_PSE);
 106 }
 107
 108 struct page *
 109 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 110                 pmd_t *pmd, int write)
 111 {
 112         struct page *page;
 113
 114         page = pte_page(*(pte_t *)pmd);
 115         if (page)
 116                 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
 117         return page;
 118 }
 119 #endif
 120
 121 void hugetlb_clean_stale_pgtable(pte_t *pte)
 122 {
 123         pmd_t *pmd = (pmd_t *) pte;
 124         struct page *page;
 125
 126         page = pmd_page(*pmd);
 127         pmd_clear(pmd);
 128         dec_page_state(nr_page_table_pages);
 129         page_cache_release(page);
 130 }
 131
 132 /* x86_64 also uses this file */
 133
 134 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 135 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 136                 unsigned long addr, unsigned long len,
 137                 unsigned long pgoff, unsigned long flags)
 138 {
 139         struct mm_struct *mm = current->mm;
 140         struct vm_area_struct *vma;
 141         unsigned long start_addr;
 142
 143         if (len > mm->cached_hole_size) {
 144                 start_addr = mm->free_area_cache;
 145         } else {
 146                 start_addr = TASK_UNMAPPED_BASE;
 147                 mm->cached_hole_size = 0;
 148         }
 149
 150 full_search:
 151         addr = ALIGN(start_addr, HPAGE_SIZE);
 152
 153         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 154                 /* At this point:  (!vma || addr < vma->vm_end). */
 155                 if (TASK_SIZE - len < addr) {
 156                         /*
 157                          * Start a new search - just in case we missed
 158                          * some holes.
 159                          */
 160                         if (start_addr != TASK_UNMAPPED_BASE) {
 161                                 start_addr = TASK_UNMAPPED_BASE;
 162                                 mm->cached_hole_size = 0;
 163                                 goto full_search;
 164                         }
 165                         return -ENOMEM;
 166                 }
 167                 if (!vma || addr + len <= vma->vm_start) {
 168                         mm->free_area_cache = addr + len;
 169                         return addr;
 170                 }
 171                 if (addr + mm->cached_hole_size < vma->vm_start)
 172                         mm->cached_hole_size = vma->vm_start - addr;
 173                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 174         }
 175 }
 176
 177 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 178                 unsigned long addr0, unsigned long len,
 179                 unsigned long pgoff, unsigned long flags)
 180 {
 181         struct mm_struct *mm = current->mm;
 182         struct vm_area_struct *vma, *prev_vma;
 183         unsigned long base = mm->mmap_base, addr = addr0;
 184         unsigned long largest_hole = mm->cached_hole_size;
 185         int first_time = 1;
 186
 187         /* don't allow allocations above current base */
 188         if (mm->free_area_cache > base)
 189                 mm->free_area_cache = base;
 190
 191         if (len <= largest_hole) {
 192                 largest_hole = 0;
 193                 mm->free_area_cache  = base;
 194         }
 195 try_again:
 196         /* make sure it can fit in the remaining address space */
 197         if (mm->free_area_cache < len)
 198                 goto fail;
 199
 200         /* either no address requested or cant fit in requested address hole */
 201         addr = (mm->free_area_cache - len) & HPAGE_MASK;
 202         do {
 203                 /*
 204                  * Lookup failure means no vma is above this address,
 205                  * i.e. return with success:
 206                  */
 207                 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
 208                         return addr;
 209
 210                 /*
 211                  * new region fits between prev_vma->vm_end and
 212                  * vma->vm_start, use it:
 213                  */
 214                 if (addr + len <= vma->vm_start &&
 215                             (!prev_vma || (addr >= prev_vma->vm_end))) {
 216                         /* remember the address as a hint for next time */
 217                         mm->cached_hole_size = largest_hole;
 218                         return (mm->free_area_cache = addr);
 219                 } else {
 220                         /* pull free_area_cache down to the first hole */
 221                         if (mm->free_area_cache == vma->vm_end) {
 222                                 mm->free_area_cache = vma->vm_start;
 223                                 mm->cached_hole_size = largest_hole;
 224                         }
 225                 }
 226
 227                 /* remember the largest hole we saw so far */
 228                 if (addr + largest_hole < vma->vm_start)
 229                         largest_hole = vma->vm_start - addr;
 230
 231                 /* try just below the current vma->vm_start */
 232                 addr = (vma->vm_start - len) & HPAGE_MASK;
 233         } while (len <= vma->vm_start);
 234
 235 fail:
 236         /*
 237          * if hint left us with no space for the requested
 238          * mapping then try again:
 239          */
 240         if (first_time) {
 241                 mm->free_area_cache = base;
 242                 largest_hole = 0;
 243                 first_time = 0;
 244                 goto try_again;
 245         }
 246         /*
 247          * A failed mmap() very likely causes application failure,
 248          * so fall back to the bottom-up function here. This scenario
 249          * can happen with large stack limits and large mmap()
 250          * allocations.
 251          */
 252         mm->free_area_cache = TASK_UNMAPPED_BASE;
 253         mm->cached_hole_size = ~0UL;
 254         addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
 255                         len, pgoff, flags);
 256
 257         /*
 258          * Restore the topdown base:
 259          */
 260         mm->free_area_cache = base;
 261         mm->cached_hole_size = ~0UL;
 262
 263         return addr;
 264 }
 265
 266 unsigned long
 267 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 268                 unsigned long len, unsigned long pgoff, unsigned long flags)
 269 {
 270         struct mm_struct *mm = current->mm;
 271         struct vm_area_struct *vma;
 272
 273         if (len & ~HPAGE_MASK)
 274                 return -EINVAL;
 275         if (len > TASK_SIZE)
 276                 return -ENOMEM;
 277
 278         if (addr) {
 279                 addr = ALIGN(addr, HPAGE_SIZE);
 280                 vma = find_vma(mm, addr);
 281                 if (TASK_SIZE - len >= addr &&
 282                     (!vma || addr + len <= vma->vm_start))
 283                         return addr;
 284         }
 285         if (mm->get_unmapped_area == arch_get_unmapped_area)
 286                 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
 287                                 pgoff, flags);
 288         else
 289                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
 290                                 pgoff, flags);
 291 }
 292
 293 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
 294