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;
  26         pte_t *pte = NULL;
  27
  28         pgd = pgd_offset(mm, addr);
  29         pud = pud_alloc(mm, pgd, addr);
  30         pmd = pmd_alloc(mm, pud, addr);
  31
  32         if (!pmd)
  33                 goto out;
  34
  35         pte = (pte_t *) pmd;
  36         if (!pte_none(*pte) && !pte_huge(*pte))
  37                 hugetlb_clean_stale_pgtable(pte);
  38 out:
  39         return pte;
  40 }
  41
  42 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
  43 {
  44         pgd_t *pgd;
  45         pud_t *pud;
  46         pmd_t *pmd = NULL;
  47
  48         pgd = pgd_offset(mm, addr);
  49         pud = pud_offset(pgd, addr);
  50         pmd = pmd_offset(pud, addr);
  51         return (pte_t *) pmd;
  52 }
  53
  54 /*
  55  * This function checks for proper alignment of input addr and len parameters.
  56  */
  57 int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
  58 {
  59         if (len & ~HPAGE_MASK)
  60                 return -EINVAL;
  61         if (addr & ~HPAGE_MASK)
  62                 return -EINVAL;
  63         return 0;
  64 }
  65
  66 #if 0   /* This is just for testing */
  67 struct page *
  68 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
  69 {
  70         unsigned long start = address;
  71         int length = 1;
  72         int nr;
  73         struct page *page;
  74         struct vm_area_struct *vma;
  75
  76         vma = find_vma(mm, addr);
  77         if (!vma || !is_vm_hugetlb_page(vma))
  78                 return ERR_PTR(-EINVAL);
  79
  80         pte = huge_pte_offset(mm, address);
  81
  82         /* hugetlb should be locked, and hence, prefaulted */
  83         WARN_ON(!pte || pte_none(*pte));
  84
  85         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
  86
  87         WARN_ON(!PageCompound(page));
  88
  89         return page;
  90 }
  91
  92 int pmd_huge(pmd_t pmd)
  93 {
  94         return 0;
  95 }
  96
  97 struct page *
  98 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
  99                 pmd_t *pmd, int write)
 100 {
 101         return NULL;
 102 }
 103
 104 #else
 105
 106 struct page *
 107 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 108 {
 109         return ERR_PTR(-EINVAL);
 110 }
 111
 112 int pmd_huge(pmd_t pmd)
 113 {
 114         return !!(pmd_val(pmd) & _PAGE_PSE);
 115 }
 116
 117 struct page *
 118 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 119                 pmd_t *pmd, int write)
 120 {
 121         struct page *page;
 122
 123         page = pte_page(*(pte_t *)pmd);
 124         if (page)
 125                 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
 126         return page;
 127 }
 128 #endif
 129
 130 void hugetlb_clean_stale_pgtable(pte_t *pte)
 131 {
 132         pmd_t *pmd = (pmd_t *) pte;
 133         struct page *page;
 134
 135         page = pmd_page(*pmd);
 136         pmd_clear(pmd);
 137         dec_page_state(nr_page_table_pages);
 138         page_cache_release(page);
 139 }
 140
 141 /* x86_64 also uses this file */
 142
 143 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 144 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 145                 unsigned long addr, unsigned long len,
 146                 unsigned long pgoff, unsigned long flags)
 147 {
 148         struct mm_struct *mm = current->mm;
 149         struct vm_area_struct *vma;
 150         unsigned long start_addr;
 151
 152         if (len > mm->cached_hole_size) {
 153                 start_addr = mm->free_area_cache;
 154         } else {
 155                 start_addr = TASK_UNMAPPED_BASE;
 156                 mm->cached_hole_size = 0;
 157         }
 158
 159 full_search:
 160         addr = ALIGN(start_addr, HPAGE_SIZE);
 161
 162         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 163                 /* At this point:  (!vma || addr < vma->vm_end). */
 164                 if (TASK_SIZE - len < addr) {
 165                         /*
 166                          * Start a new search - just in case we missed
 167                          * some holes.
 168                          */
 169                         if (start_addr != TASK_UNMAPPED_BASE) {
 170                                 start_addr = TASK_UNMAPPED_BASE;
 171                                 mm->cached_hole_size = 0;
 172                                 goto full_search;
 173                         }
 174                         return -ENOMEM;
 175                 }
 176                 if (!vma || addr + len <= vma->vm_start) {
 177                         mm->free_area_cache = addr + len;
 178                         return addr;
 179                 }
 180                 if (addr + mm->cached_hole_size < vma->vm_start)
 181                         mm->cached_hole_size = vma->vm_start - addr;
 182                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 183         }
 184 }
 185
 186 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 187                 unsigned long addr0, unsigned long len,
 188                 unsigned long pgoff, unsigned long flags)
 189 {
 190         struct mm_struct *mm = current->mm;
 191         struct vm_area_struct *vma, *prev_vma;
 192         unsigned long base = mm->mmap_base, addr = addr0;
 193         unsigned long largest_hole = mm->cached_hole_size;
 194         int first_time = 1;
 195
 196         /* don't allow allocations above current base */
 197         if (mm->free_area_cache > base)
 198                 mm->free_area_cache = base;
 199
 200         if (len <= largest_hole) {
 201                 largest_hole = 0;
 202                 mm->free_area_cache  = base;
 203         }
 204 try_again:
 205         /* make sure it can fit in the remaining address space */
 206         if (mm->free_area_cache < len)
 207                 goto fail;
 208
 209         /* either no address requested or cant fit in requested address hole */
 210         addr = (mm->free_area_cache - len) & HPAGE_MASK;
 211         do {
 212                 /*
 213                  * Lookup failure means no vma is above this address,
 214                  * i.e. return with success:
 215                  */
 216                 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
 217                         return addr;
 218
 219                 /*
 220                  * new region fits between prev_vma->vm_end and
 221                  * vma->vm_start, use it:
 222                  */
 223                 if (addr + len <= vma->vm_start &&
 224                             (!prev_vma || (addr >= prev_vma->vm_end))) {
 225                         /* remember the address as a hint for next time */
 226                         mm->cached_hole_size = largest_hole;
 227                         return (mm->free_area_cache = addr);
 228                 } else {
 229                         /* pull free_area_cache down to the first hole */
 230                         if (mm->free_area_cache == vma->vm_end) {
 231                                 mm->free_area_cache = vma->vm_start;
 232                                 mm->cached_hole_size = largest_hole;
 233                         }
 234                 }
 235
 236                 /* remember the largest hole we saw so far */
 237                 if (addr + largest_hole < vma->vm_start)
 238                         largest_hole = vma->vm_start - addr;
 239
 240                 /* try just below the current vma->vm_start */
 241                 addr = (vma->vm_start - len) & HPAGE_MASK;
 242         } while (len <= vma->vm_start);
 243
 244 fail:
 245         /*
 246          * if hint left us with no space for the requested
 247          * mapping then try again:
 248          */
 249         if (first_time) {
 250                 mm->free_area_cache = base;
 251                 largest_hole = 0;
 252                 first_time = 0;
 253                 goto try_again;
 254         }
 255         /*
 256          * A failed mmap() very likely causes application failure,
 257          * so fall back to the bottom-up function here. This scenario
 258          * can happen with large stack limits and large mmap()
 259          * allocations.
 260          */
 261         mm->free_area_cache = TASK_UNMAPPED_BASE;
 262         mm->cached_hole_size = ~0UL;
 263         addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
 264                         len, pgoff, flags);
 265
 266         /*
 267          * Restore the topdown base:
 268          */
 269         mm->free_area_cache = base;
 270         mm->cached_hole_size = ~0UL;
 271
 272         return addr;
 273 }
 274
 275 unsigned long
 276 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 277                 unsigned long len, unsigned long pgoff, unsigned long flags)
 278 {
 279         struct mm_struct *mm = current->mm;
 280         struct vm_area_struct *vma;
 281
 282         if (len & ~HPAGE_MASK)
 283                 return -EINVAL;
 284         if (len > TASK_SIZE)
 285                 return -ENOMEM;
 286
 287         if (addr) {
 288                 addr = ALIGN(addr, HPAGE_SIZE);
 289                 vma = find_vma(mm, addr);
 290                 if (TASK_SIZE - len >= addr &&
 291                     (!vma || addr + len <= vma->vm_start))
 292                         return addr;
 293         }
 294         if (mm->get_unmapped_area == arch_get_unmapped_area)
 295                 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
 296                                 pgoff, flags);
 297         else
 298                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
 299                                 pgoff, flags);
 300 }
 301
 302 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
 303