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   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 static 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 static 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 static void set_huge_pte(struct mm_struct *mm, struct vm_area_struct *vma, struct page *page, pte_t * page_table, int write_access)
  46 {
  47         pte_t entry;
  48
  49         add_mm_counter(mm, rss, HPAGE_SIZE / PAGE_SIZE);
  50         if (write_access) {
  51                 entry =
  52                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
  53         } else
  54                 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
  55         entry = pte_mkyoung(entry);
  56         mk_pte_huge(entry);
  57         set_pte(page_table, entry);
  58 }
  59
  60 /*
  61  * This function checks for proper alignment of input addr and len parameters.
  62  */
  63 int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
  64 {
  65         if (len & ~HPAGE_MASK)
  66                 return -EINVAL;
  67         if (addr & ~HPAGE_MASK)
  68                 return -EINVAL;
  69         return 0;
  70 }
  71
  72 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
  73                         struct vm_area_struct *vma)
  74 {
  75         pte_t *src_pte, *dst_pte, entry;
  76         struct page *ptepage;
  77         unsigned long addr = vma->vm_start;
  78         unsigned long end = vma->vm_end;
  79
  80         while (addr < end) {
  81                 dst_pte = huge_pte_alloc(dst, addr);
  82                 if (!dst_pte)
  83                         goto nomem;
  84                 src_pte = huge_pte_offset(src, addr);
  85                 entry = *src_pte;
  86                 ptepage = pte_page(entry);
  87                 get_page(ptepage);
  88                 set_pte(dst_pte, entry);
  89                 add_mm_counter(dst, rss, HPAGE_SIZE / PAGE_SIZE);
  90                 addr += HPAGE_SIZE;
  91         }
  92         return 0;
  93
  94 nomem:
  95         return -ENOMEM;
  96 }
  97
  98 int
  99 follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 100                     struct page **pages, struct vm_area_struct **vmas,
 101                     unsigned long *position, int *length, int i)
 102 {
 103         unsigned long vpfn, vaddr = *position;
 104         int remainder = *length;
 105
 106         WARN_ON(!is_vm_hugetlb_page(vma));
 107
 108         vpfn = vaddr/PAGE_SIZE;
 109         while (vaddr < vma->vm_end && remainder) {
 110
 111                 if (pages) {
 112                         pte_t *pte;
 113                         struct page *page;
 114
 115                         pte = huge_pte_offset(mm, vaddr);
 116
 117                         /* hugetlb should be locked, and hence, prefaulted */
 118                         WARN_ON(!pte || pte_none(*pte));
 119
 120                         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
 121
 122                         WARN_ON(!PageCompound(page));
 123
 124                         get_page(page);
 125                         pages[i] = page;
 126                 }
 127
 128                 if (vmas)
 129                         vmas[i] = vma;
 130
 131                 vaddr += PAGE_SIZE;
 132                 ++vpfn;
 133                 --remainder;
 134                 ++i;
 135         }
 136
 137         *length = remainder;
 138         *position = vaddr;
 139
 140         return i;
 141 }
 142
 143 #if 0   /* This is just for testing */
 144 struct page *
 145 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 146 {
 147         unsigned long start = address;
 148         int length = 1;
 149         int nr;
 150         struct page *page;
 151         struct vm_area_struct *vma;
 152
 153         vma = find_vma(mm, addr);
 154         if (!vma || !is_vm_hugetlb_page(vma))
 155                 return ERR_PTR(-EINVAL);
 156
 157         pte = huge_pte_offset(mm, address);
 158
 159         /* hugetlb should be locked, and hence, prefaulted */
 160         WARN_ON(!pte || pte_none(*pte));
 161
 162         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
 163
 164         WARN_ON(!PageCompound(page));
 165
 166         return page;
 167 }
 168
 169 int pmd_huge(pmd_t pmd)
 170 {
 171         return 0;
 172 }
 173
 174 struct page *
 175 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 176                 pmd_t *pmd, int write)
 177 {
 178         return NULL;
 179 }
 180
 181 #else
 182
 183 struct page *
 184 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 185 {
 186         return ERR_PTR(-EINVAL);
 187 }
 188
 189 int pmd_huge(pmd_t pmd)
 190 {
 191         return !!(pmd_val(pmd) & _PAGE_PSE);
 192 }
 193
 194 struct page *
 195 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 196                 pmd_t *pmd, int write)
 197 {
 198         struct page *page;
 199
 200         page = pte_page(*(pte_t *)pmd);
 201         if (page)
 202                 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
 203         return page;
 204 }
 205 #endif
 206
 207 void unmap_hugepage_range(struct vm_area_struct *vma,
 208                 unsigned long start, unsigned long end)
 209 {
 210         struct mm_struct *mm = vma->vm_mm;
 211         unsigned long address;
 212         pte_t pte, *ptep;
 213         struct page *page;
 214
 215         BUG_ON(start & (HPAGE_SIZE - 1));
 216         BUG_ON(end & (HPAGE_SIZE - 1));
 217
 218         for (address = start; address < end; address += HPAGE_SIZE) {
 219                 ptep = huge_pte_offset(mm, address);
 220                 if (!ptep)
 221                         continue;
 222                 pte = ptep_get_and_clear(mm, address, ptep);
 223                 if (pte_none(pte))
 224                         continue;
 225                 page = pte_page(pte);
 226                 put_page(page);
 227         }
 228         add_mm_counter(mm ,rss, -((end - start) >> PAGE_SHIFT));
 229         flush_tlb_range(vma, start, end);
 230 }
 231
 232 int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
 233 {
 234         struct mm_struct *mm = current->mm;
 235         unsigned long addr;
 236         int ret = 0;
 237
 238         BUG_ON(vma->vm_start & ~HPAGE_MASK);
 239         BUG_ON(vma->vm_end & ~HPAGE_MASK);
 240
 241         spin_lock(&mm->page_table_lock);
 242         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
 243                 unsigned long idx;
 244                 pte_t *pte = huge_pte_alloc(mm, addr);
 245                 struct page *page;
 246
 247                 if (!pte) {
 248                         ret = -ENOMEM;
 249                         goto out;
 250                 }
 251
 252                 if (!pte_none(*pte)) {
 253                         pmd_t *pmd = (pmd_t *) pte;
 254
 255                         page = pmd_page(*pmd);
 256                         pmd_clear(pmd);
 257                         mm->nr_ptes--;
 258                         dec_page_state(nr_page_table_pages);
 259                         page_cache_release(page);
 260                 }
 261
 262                 idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
 263                         + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
 264                 page = find_get_page(mapping, idx);
 265                 if (!page) {
 266                         /* charge the fs quota first */
 267                         if (hugetlb_get_quota(mapping)) {
 268                                 ret = -ENOMEM;
 269                                 goto out;
 270                         }
 271                         page = alloc_huge_page();
 272                         if (!page) {
 273                                 hugetlb_put_quota(mapping);
 274                                 ret = -ENOMEM;
 275                                 goto out;
 276                         }
 277                         ret = add_to_page_cache(page, mapping, idx, GFP_ATOMIC);
 278                         if (! ret) {
 279                                 unlock_page(page);
 280                         } else {
 281                                 hugetlb_put_quota(mapping);
 282                                 free_huge_page(page);
 283                                 goto out;
 284                         }
 285                 }
 286                 set_huge_pte(mm, vma, page, pte, vma->vm_flags & VM_WRITE);
 287         }
 288 out:
 289         spin_unlock(&mm->page_table_lock);
 290         return ret;
 291 }
 292
 293 /* x86_64 also uses this file */
 294
 295 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 296 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 297                 unsigned long addr, unsigned long len,
 298                 unsigned long pgoff, unsigned long flags)
 299 {
 300         struct mm_struct *mm = current->mm;
 301         struct vm_area_struct *vma;
 302         unsigned long start_addr;
 303
 304         start_addr = mm->free_area_cache;
 305
 306 full_search:
 307         addr = ALIGN(start_addr, HPAGE_SIZE);
 308
 309         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 310                 /* At this point:  (!vma || addr < vma->vm_end). */
 311                 if (TASK_SIZE - len < addr) {
 312                         /*
 313                          * Start a new search - just in case we missed
 314                          * some holes.
 315                          */
 316                         if (start_addr != TASK_UNMAPPED_BASE) {
 317                                 start_addr = TASK_UNMAPPED_BASE;
 318                                 goto full_search;
 319                         }
 320                         return -ENOMEM;
 321                 }
 322                 if (!vma || addr + len <= vma->vm_start) {
 323                         mm->free_area_cache = addr + len;
 324                         return addr;
 325                 }
 326                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 327         }
 328 }
 329
 330 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 331                 unsigned long addr0, unsigned long len,
 332                 unsigned long pgoff, unsigned long flags)
 333 {
 334         struct mm_struct *mm = current->mm;
 335         struct vm_area_struct *vma, *prev_vma;
 336         unsigned long base = mm->mmap_base, addr = addr0;
 337         int first_time = 1;
 338
 339         /* don't allow allocations above current base */
 340         if (mm->free_area_cache > base)
 341                 mm->free_area_cache = base;
 342
 343 try_again:
 344         /* make sure it can fit in the remaining address space */
 345         if (mm->free_area_cache < len)
 346                 goto fail;
 347
 348         /* either no address requested or cant fit in requested address hole */
 349         addr = (mm->free_area_cache - len) & HPAGE_MASK;
 350         do {
 351                 /*
 352                  * Lookup failure means no vma is above this address,
 353                  * i.e. return with success:
 354                  */
 355                 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
 356                         return addr;
 357
 358                 /*
 359                  * new region fits between prev_vma->vm_end and
 360                  * vma->vm_start, use it:
 361                  */
 362                 if (addr + len <= vma->vm_start &&
 363                                 (!prev_vma || (addr >= prev_vma->vm_end)))
 364                         /* remember the address as a hint for next time */
 365                         return (mm->free_area_cache = addr);
 366                 else
 367                         /* pull free_area_cache down to the first hole */
 368                         if (mm->free_area_cache == vma->vm_end)
 369                                 mm->free_area_cache = vma->vm_start;
 370
 371                 /* try just below the current vma->vm_start */
 372                 addr = (vma->vm_start - len) & HPAGE_MASK;
 373         } while (len <= vma->vm_start);
 374
 375 fail:
 376         /*
 377          * if hint left us with no space for the requested
 378          * mapping then try again:
 379          */
 380         if (first_time) {
 381                 mm->free_area_cache = base;
 382                 first_time = 0;
 383                 goto try_again;
 384         }
 385         /*
 386          * A failed mmap() very likely causes application failure,
 387          * so fall back to the bottom-up function here. This scenario
 388          * can happen with large stack limits and large mmap()
 389          * allocations.
 390          */
 391         mm->free_area_cache = TASK_UNMAPPED_BASE;
 392         addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
 393                         len, pgoff, flags);
 394
 395         /*
 396          * Restore the topdown base:
 397          */
 398         mm->free_area_cache = base;
 399
 400         return addr;
 401 }
 402
 403 unsigned long
 404 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 405                 unsigned long len, unsigned long pgoff, unsigned long flags)
 406 {
 407         struct mm_struct *mm = current->mm;
 408         struct vm_area_struct *vma;
 409
 410         if (len & ~HPAGE_MASK)
 411                 return -EINVAL;
 412         if (len > TASK_SIZE)
 413                 return -ENOMEM;
 414
 415         if (addr) {
 416                 addr = ALIGN(addr, HPAGE_SIZE);
 417                 vma = find_vma(mm, addr);
 418                 if (TASK_SIZE - len >= addr &&
 419                     (!vma || addr + len <= vma->vm_start))
 420                         return addr;
 421         }
 422         if (mm->get_unmapped_area == arch_get_unmapped_area)
 423                 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
 424                                 pgoff, flags);
 425         else
 426                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
 427                                 pgoff, flags);
 428 }
 429
 430 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
 431