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