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