include/asm-generic/pgtable.h

   1 #ifndef _ASM_GENERIC_PGTABLE_H
   2 #define _ASM_GENERIC_PGTABLE_H
   3
   4 #include <linux/pfn.h>
   5
   6 #ifndef __ASSEMBLY__
   7 #ifdef CONFIG_MMU
   8
   9 #include <linux/mm_types.h>
  10 #include <linux/bug.h>
  11 #include <linux/errno.h>
  12
  13 #if 4 - defined(__PAGETABLE_PUD_FOLDED) - defined(__PAGETABLE_PMD_FOLDED) != \
  14         CONFIG_PGTABLE_LEVELS
  15 #error CONFIG_PGTABLE_LEVELS is not consistent with __PAGETABLE_{PUD,PMD}_FOLDED
  16 #endif
  17
  18 /*
  19  * On almost all architectures and configurations, 0 can be used as the
  20  * upper ceiling to free_pgtables(): on many architectures it has the same
  21  * effect as using TASK_SIZE.  However, there is one configuration which
  22  * must impose a more careful limit, to avoid freeing kernel pgtables.
  23  */
  24 #ifndef USER_PGTABLES_CEILING
  25 #define USER_PGTABLES_CEILING   0UL
  26 #endif
  27
  28 #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
  29 extern int ptep_set_access_flags(struct vm_area_struct *vma,
  30                                  unsigned long address, pte_t *ptep,
  31                                  pte_t entry, int dirty);
  32 #endif
  33
  34 #ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
  35 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  36 extern int pmdp_set_access_flags(struct vm_area_struct *vma,
  37                                  unsigned long address, pmd_t *pmdp,
  38                                  pmd_t entry, int dirty);
  39 #else
  40 static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
  41                                         unsigned long address, pmd_t *pmdp,
  42                                         pmd_t entry, int dirty)
  43 {
  44         BUILD_BUG();
  45         return 0;
  46 }
  47 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
  48 #endif
  49
  50 #ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
  51 static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
  52                                             unsigned long address,
  53                                             pte_t *ptep)
  54 {
  55         pte_t pte = *ptep;
  56         int r = 1;
  57         if (!pte_young(pte))
  58                 r = 0;
  59         else
  60                 set_pte_at(vma->vm_mm, address, ptep, pte_mkold(pte));
  61         return r;
  62 }
  63 #endif
  64
  65 #ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
  66 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  67 static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
  68                                             unsigned long address,
  69                                             pmd_t *pmdp)
  70 {
  71         pmd_t pmd = *pmdp;
  72         int r = 1;
  73         if (!pmd_young(pmd))
  74                 r = 0;
  75         else
  76                 set_pmd_at(vma->vm_mm, address, pmdp, pmd_mkold(pmd));
  77         return r;
  78 }
  79 #else
  80 static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
  81                                             unsigned long address,
  82                                             pmd_t *pmdp)
  83 {
  84         BUILD_BUG();
  85         return 0;
  86 }
  87 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
  88 #endif
  89
  90 #ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
  91 int ptep_clear_flush_young(struct vm_area_struct *vma,
  92                            unsigned long address, pte_t *ptep);
  93 #endif
  94
  95 #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
  96 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  97 extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
  98                                   unsigned long address, pmd_t *pmdp);
  99 #else
 100 /*
 101  * Despite relevant to THP only, this API is called from generic rmap code
 102  * under PageTransHuge(), hence needs a dummy implementation for !THP
 103  */
 104 static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
 105                                          unsigned long address, pmd_t *pmdp)
 106 {
 107         BUILD_BUG();
 108         return 0;
 109 }
 110 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 111 #endif
 112
 113 #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
 114 static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 115                                        unsigned long address,
 116                                        pte_t *ptep)
 117 {
 118         pte_t pte = *ptep;
 119         pte_clear(mm, address, ptep);
 120         return pte;
 121 }
 122 #endif
 123
 124 #ifndef __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
 125 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 126 static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 127                                             unsigned long address,
 128                                             pmd_t *pmdp)
 129 {
 130         pmd_t pmd = *pmdp;
 131         pmd_clear(pmdp);
 132         return pmd;
 133 }
 134 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 135 #endif
 136
 137 #ifndef __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR_FULL
 138 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 139 static inline pmd_t pmdp_huge_get_and_clear_full(struct mm_struct *mm,
 140                                             unsigned long address, pmd_t *pmdp,
 141                                             int full)
 142 {
 143         return pmdp_huge_get_and_clear(mm, address, pmdp);
 144 }
 145 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 146 #endif
 147
 148 #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
 149 static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
 150                                             unsigned long address, pte_t *ptep,
 151                                             int full)
 152 {
 153         pte_t pte;
 154         pte = ptep_get_and_clear(mm, address, ptep);
 155         return pte;
 156 }
 157 #endif
 158
 159 /*
 160  * Some architectures may be able to avoid expensive synchronization
 161  * primitives when modifications are made to PTE's which are already
 162  * not present, or in the process of an address space destruction.
 163  */
 164 #ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL
 165 static inline void pte_clear_not_present_full(struct mm_struct *mm,
 166                                               unsigned long address,
 167                                               pte_t *ptep,
 168                                               int full)
 169 {
 170         pte_clear(mm, address, ptep);
 171 }
 172 #endif
 173
 174 #ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
 175 extern pte_t ptep_clear_flush(struct vm_area_struct *vma,
 176                               unsigned long address,
 177                               pte_t *ptep);
 178 #endif
 179
 180 #ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
 181 extern pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma,
 182                               unsigned long address,
 183                               pmd_t *pmdp);
 184 #endif
 185
 186 #ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT
 187 struct mm_struct;
 188 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
 189 {
 190         pte_t old_pte = *ptep;
 191         set_pte_at(mm, address, ptep, pte_wrprotect(old_pte));
 192 }
 193 #endif
 194
 195 #ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
 196 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 197 static inline void pmdp_set_wrprotect(struct mm_struct *mm,
 198                                       unsigned long address, pmd_t *pmdp)
 199 {
 200         pmd_t old_pmd = *pmdp;
 201         set_pmd_at(mm, address, pmdp, pmd_wrprotect(old_pmd));
 202 }
 203 #else
 204 static inline void pmdp_set_wrprotect(struct mm_struct *mm,
 205                                       unsigned long address, pmd_t *pmdp)
 206 {
 207         BUILD_BUG();
 208 }
 209 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 210 #endif
 211
 212 #ifndef pmdp_collapse_flush
 213 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 214 extern pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
 215                                  unsigned long address, pmd_t *pmdp);
 216 #else
 217 static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
 218                                         unsigned long address,
 219                                         pmd_t *pmdp)
 220 {
 221         BUILD_BUG();
 222         return *pmdp;
 223 }
 224 #define pmdp_collapse_flush pmdp_collapse_flush
 225 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 226 #endif
 227
 228 #ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
 229 extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
 230                                        pgtable_t pgtable);
 231 #endif
 232
 233 #ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
 234 extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
 235 #endif
 236
 237 #ifndef __HAVE_ARCH_PMDP_INVALIDATE
 238 extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
 239                             pmd_t *pmdp);
 240 #endif
 241
 242 #ifndef __HAVE_ARCH_PTE_SAME
 243 static inline int pte_same(pte_t pte_a, pte_t pte_b)
 244 {
 245         return pte_val(pte_a) == pte_val(pte_b);
 246 }
 247 #endif
 248
 249 #ifndef __HAVE_ARCH_PTE_UNUSED
 250 /*
 251  * Some architectures provide facilities to virtualization guests
 252  * so that they can flag allocated pages as unused. This allows the
 253  * host to transparently reclaim unused pages. This function returns
 254  * whether the pte's page is unused.
 255  */
 256 static inline int pte_unused(pte_t pte)
 257 {
 258         return 0;
 259 }
 260 #endif
 261
 262 #ifndef __HAVE_ARCH_PMD_SAME
 263 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 264 static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
 265 {
 266         return pmd_val(pmd_a) == pmd_val(pmd_b);
 267 }
 268 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
 269 static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
 270 {
 271         BUILD_BUG();
 272         return 0;
 273 }
 274 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 275 #endif
 276
 277 #ifndef __HAVE_ARCH_PGD_OFFSET_GATE
 278 #define pgd_offset_gate(mm, addr)       pgd_offset(mm, addr)
 279 #endif
 280
 281 #ifndef __HAVE_ARCH_MOVE_PTE
 282 #define move_pte(pte, prot, old_addr, new_addr) (pte)
 283 #endif
 284
 285 #ifndef pte_accessible
 286 # define pte_accessible(mm, pte)        ((void)(pte), 1)
 287 #endif
 288
 289 #ifndef flush_tlb_fix_spurious_fault
 290 #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
 291 #endif
 292
 293 #ifndef pgprot_noncached
 294 #define pgprot_noncached(prot)  (prot)
 295 #endif
 296
 297 #ifndef pgprot_writecombine
 298 #define pgprot_writecombine pgprot_noncached
 299 #endif
 300
 301 #ifndef pgprot_writethrough
 302 #define pgprot_writethrough pgprot_noncached
 303 #endif
 304
 305 #ifndef pgprot_device
 306 #define pgprot_device pgprot_noncached
 307 #endif
 308
 309 #ifndef pgprot_modify
 310 #define pgprot_modify pgprot_modify
 311 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 312 {
 313         if (pgprot_val(oldprot) == pgprot_val(pgprot_noncached(oldprot)))
 314                 newprot = pgprot_noncached(newprot);
 315         if (pgprot_val(oldprot) == pgprot_val(pgprot_writecombine(oldprot)))
 316                 newprot = pgprot_writecombine(newprot);
 317         if (pgprot_val(oldprot) == pgprot_val(pgprot_device(oldprot)))
 318                 newprot = pgprot_device(newprot);
 319         return newprot;
 320 }
 321 #endif
 322
 323 /*
 324  * When walking page tables, get the address of the next boundary,
 325  * or the end address of the range if that comes earlier.  Although no
 326  * vma end wraps to 0, rounded up __boundary may wrap to 0 throughout.
 327  */
 328
 329 #define pgd_addr_end(addr, end)                                         \
 330 ({      unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK;  \
 331         (__boundary - 1 < (end) - 1)? __boundary: (end);                \
 332 })
 333
 334 #ifndef pud_addr_end
 335 #define pud_addr_end(addr, end)                                         \
 336 ({      unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK;      \
 337         (__boundary - 1 < (end) - 1)? __boundary: (end);                \
 338 })
 339 #endif
 340
 341 #ifndef pmd_addr_end
 342 #define pmd_addr_end(addr, end)                                         \
 343 ({      unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK;      \
 344         (__boundary - 1 < (end) - 1)? __boundary: (end);                \
 345 })
 346 #endif
 347
 348 /*
 349  * When walking page tables, we usually want to skip any p?d_none entries;
 350  * and any p?d_bad entries - reporting the error before resetting to none.
 351  * Do the tests inline, but report and clear the bad entry in mm/memory.c.
 352  */
 353 void pgd_clear_bad(pgd_t *);
 354 void pud_clear_bad(pud_t *);
 355 void pmd_clear_bad(pmd_t *);
 356
 357 static inline int pgd_none_or_clear_bad(pgd_t *pgd)
 358 {
 359         if (pgd_none(*pgd))
 360                 return 1;
 361         if (unlikely(pgd_bad(*pgd))) {
 362                 pgd_clear_bad(pgd);
 363                 return 1;
 364         }
 365         return 0;
 366 }
 367
 368 static inline int pud_none_or_clear_bad(pud_t *pud)
 369 {
 370         if (pud_none(*pud))
 371                 return 1;
 372         if (unlikely(pud_bad(*pud))) {
 373                 pud_clear_bad(pud);
 374                 return 1;
 375         }
 376         return 0;
 377 }
 378
 379 static inline int pmd_none_or_clear_bad(pmd_t *pmd)
 380 {
 381         if (pmd_none(*pmd))
 382                 return 1;
 383         if (unlikely(pmd_bad(*pmd))) {
 384                 pmd_clear_bad(pmd);
 385                 return 1;
 386         }
 387         return 0;
 388 }
 389
 390 static inline pte_t __ptep_modify_prot_start(struct mm_struct *mm,
 391                                              unsigned long addr,
 392                                              pte_t *ptep)
 393 {
 394         /*
 395          * Get the current pte state, but zero it out to make it
 396          * non-present, preventing the hardware from asynchronously
 397          * updating it.
 398          */
 399         return ptep_get_and_clear(mm, addr, ptep);
 400 }
 401
 402 static inline void __ptep_modify_prot_commit(struct mm_struct *mm,
 403                                              unsigned long addr,
 404                                              pte_t *ptep, pte_t pte)
 405 {
 406         /*
 407          * The pte is non-present, so there's no hardware state to
 408          * preserve.
 409          */
 410         set_pte_at(mm, addr, ptep, pte);
 411 }
 412
 413 #ifndef __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
 414 /*
 415  * Start a pte protection read-modify-write transaction, which
 416  * protects against asynchronous hardware modifications to the pte.
 417  * The intention is not to prevent the hardware from making pte
 418  * updates, but to prevent any updates it may make from being lost.
 419  *
 420  * This does not protect against other software modifications of the
 421  * pte; the appropriate pte lock must be held over the transation.
 422  *
 423  * Note that this interface is intended to be batchable, meaning that
 424  * ptep_modify_prot_commit may not actually update the pte, but merely
 425  * queue the update to be done at some later time.  The update must be
 426  * actually committed before the pte lock is released, however.
 427  */
 428 static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
 429                                            unsigned long addr,
 430                                            pte_t *ptep)
 431 {
 432         return __ptep_modify_prot_start(mm, addr, ptep);
 433 }
 434
 435 /*
 436  * Commit an update to a pte, leaving any hardware-controlled bits in
 437  * the PTE unmodified.
 438  */
 439 static inline void ptep_modify_prot_commit(struct mm_struct *mm,
 440                                            unsigned long addr,
 441                                            pte_t *ptep, pte_t pte)
 442 {
 443         __ptep_modify_prot_commit(mm, addr, ptep, pte);
 444 }
 445 #endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
 446 #endif /* CONFIG_MMU */
 447
 448 /*
 449  * A facility to provide lazy MMU batching.  This allows PTE updates and
 450  * page invalidations to be delayed until a call to leave lazy MMU mode
 451  * is issued.  Some architectures may benefit from doing this, and it is
 452  * beneficial for both shadow and direct mode hypervisors, which may batch
 453  * the PTE updates which happen during this window.  Note that using this
 454  * interface requires that read hazards be removed from the code.  A read
 455  * hazard could result in the direct mode hypervisor case, since the actual
 456  * write to the page tables may not yet have taken place, so reads though
 457  * a raw PTE pointer after it has been modified are not guaranteed to be
 458  * up to date.  This mode can only be entered and left under the protection of
 459  * the page table locks for all page tables which may be modified.  In the UP
 460  * case, this is required so that preemption is disabled, and in the SMP case,
 461  * it must synchronize the delayed page table writes properly on other CPUs.
 462  */
 463 #ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
 464 #define arch_enter_lazy_mmu_mode()      do {} while (0)
 465 #define arch_leave_lazy_mmu_mode()      do {} while (0)
 466 #define arch_flush_lazy_mmu_mode()      do {} while (0)
 467 #endif
 468
 469 /*
 470  * A facility to provide batching of the reload of page tables and
 471  * other process state with the actual context switch code for
 472  * paravirtualized guests.  By convention, only one of the batched
 473  * update (lazy) modes (CPU, MMU) should be active at any given time,
 474  * entry should never be nested, and entry and exits should always be
 475  * paired.  This is for sanity of maintaining and reasoning about the
 476  * kernel code.  In this case, the exit (end of the context switch) is
 477  * in architecture-specific code, and so doesn't need a generic
 478  * definition.
 479  */
 480 #ifndef __HAVE_ARCH_START_CONTEXT_SWITCH
 481 #define arch_start_context_switch(prev) do {} while (0)
 482 #endif
 483
 484 #ifndef CONFIG_HAVE_ARCH_SOFT_DIRTY
 485 static inline int pte_soft_dirty(pte_t pte)
 486 {
 487         return 0;
 488 }
 489
 490 static inline int pmd_soft_dirty(pmd_t pmd)
 491 {
 492         return 0;
 493 }
 494
 495 static inline pte_t pte_mksoft_dirty(pte_t pte)
 496 {
 497         return pte;
 498 }
 499
 500 static inline pmd_t pmd_mksoft_dirty(pmd_t pmd)
 501 {
 502         return pmd;
 503 }
 504
 505 static inline pte_t pte_clear_soft_dirty(pte_t pte)
 506 {
 507         return pte;
 508 }
 509
 510 static inline pmd_t pmd_clear_soft_dirty(pmd_t pmd)
 511 {
 512         return pmd;
 513 }
 514
 515 static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
 516 {
 517         return pte;
 518 }
 519
 520 static inline int pte_swp_soft_dirty(pte_t pte)
 521 {
 522         return 0;
 523 }
 524
 525 static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
 526 {
 527         return pte;
 528 }
 529 #endif
 530
 531 #ifndef __HAVE_PFNMAP_TRACKING
 532 /*
 533  * Interfaces that can be used by architecture code to keep track of
 534  * memory type of pfn mappings specified by the remap_pfn_range,
 535  * vm_insert_pfn.
 536  */
 537
 538 /*
 539  * track_pfn_remap is called when a _new_ pfn mapping is being established
 540  * by remap_pfn_range() for physical range indicated by pfn and size.
 541  */
 542 static inline int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
 543                                   unsigned long pfn, unsigned long addr,
 544                                   unsigned long size)
 545 {
 546         return 0;
 547 }
 548
 549 /*
 550  * track_pfn_insert is called when a _new_ single pfn is established
 551  * by vm_insert_pfn().
 552  */
 553 static inline int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
 554                                    pfn_t pfn)
 555 {
 556         return 0;
 557 }
 558
 559 /*
 560  * track_pfn_copy is called when vma that is covering the pfnmap gets
 561  * copied through copy_page_range().
 562  */
 563 static inline int track_pfn_copy(struct vm_area_struct *vma)
 564 {
 565         return 0;
 566 }
 567
 568 /*
 569  * untrack_pfn is called while unmapping a pfnmap for a region.
 570  * untrack can be called for a specific region indicated by pfn and size or
 571  * can be for the entire vma (in which case pfn, size are zero).
 572  */
 573 static inline void untrack_pfn(struct vm_area_struct *vma,
 574                                unsigned long pfn, unsigned long size)
 575 {
 576 }
 577
 578 /*
 579  * untrack_pfn_moved is called while mremapping a pfnmap for a new region.
 580  */
 581 static inline void untrack_pfn_moved(struct vm_area_struct *vma)
 582 {
 583 }
 584 #else
 585 extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
 586                            unsigned long pfn, unsigned long addr,
 587                            unsigned long size);
 588 extern int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
 589                             pfn_t pfn);
 590 extern int track_pfn_copy(struct vm_area_struct *vma);
 591 extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
 592                         unsigned long size);
 593 extern void untrack_pfn_moved(struct vm_area_struct *vma);
 594 #endif
 595
 596 #ifdef __HAVE_COLOR_ZERO_PAGE
 597 static inline int is_zero_pfn(unsigned long pfn)
 598 {
 599         extern unsigned long zero_pfn;
 600         unsigned long offset_from_zero_pfn = pfn - zero_pfn;
 601         return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT);
 602 }
 603
 604 #define my_zero_pfn(addr)       page_to_pfn(ZERO_PAGE(addr))
 605
 606 #else
 607 static inline int is_zero_pfn(unsigned long pfn)
 608 {
 609         extern unsigned long zero_pfn;
 610         return pfn == zero_pfn;
 611 }
 612
 613 static inline unsigned long my_zero_pfn(unsigned long addr)
 614 {
 615         extern unsigned long zero_pfn;
 616         return zero_pfn;
 617 }
 618 #endif
 619
 620 #ifdef CONFIG_MMU
 621
 622 #ifndef CONFIG_TRANSPARENT_HUGEPAGE
 623 static inline int pmd_trans_huge(pmd_t pmd)
 624 {
 625         return 0;
 626 }
 627 #ifndef __HAVE_ARCH_PMD_WRITE
 628 static inline int pmd_write(pmd_t pmd)
 629 {
 630         BUG();
 631         return 0;
 632 }
 633 #endif /* __HAVE_ARCH_PMD_WRITE */
 634 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 635
 636 #ifndef pmd_read_atomic
 637 static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 638 {
 639         /*
 640          * Depend on compiler for an atomic pmd read. NOTE: this is
 641          * only going to work, if the pmdval_t isn't larger than
 642          * an unsigned long.
 643          */
 644         return *pmdp;
 645 }
 646 #endif
 647
 648 #ifndef pmd_move_must_withdraw
 649 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
 650                                          spinlock_t *old_pmd_ptl)
 651 {
 652         /*
 653          * With split pmd lock we also need to move preallocated
 654          * PTE page table if new_pmd is on different PMD page table.
 655          */
 656         return new_pmd_ptl != old_pmd_ptl;
 657 }
 658 #endif
 659
 660 /*
 661  * This function is meant to be used by sites walking pagetables with
 662  * the mmap_sem hold in read mode to protect against MADV_DONTNEED and
 663  * transhuge page faults. MADV_DONTNEED can convert a transhuge pmd
 664  * into a null pmd and the transhuge page fault can convert a null pmd
 665  * into an hugepmd or into a regular pmd (if the hugepage allocation
 666  * fails). While holding the mmap_sem in read mode the pmd becomes
 667  * stable and stops changing under us only if it's not null and not a
 668  * transhuge pmd. When those races occurs and this function makes a
 669  * difference vs the standard pmd_none_or_clear_bad, the result is
 670  * undefined so behaving like if the pmd was none is safe (because it
 671  * can return none anyway). The compiler level barrier() is critically
 672  * important to compute the two checks atomically on the same pmdval.
 673  *
 674  * For 32bit kernels with a 64bit large pmd_t this automatically takes
 675  * care of reading the pmd atomically to avoid SMP race conditions
 676  * against pmd_populate() when the mmap_sem is hold for reading by the
 677  * caller (a special atomic read not done by "gcc" as in the generic
 678  * version above, is also needed when THP is disabled because the page
 679  * fault can populate the pmd from under us).
 680  */
 681 static inline int pmd_none_or_trans_huge_or_clear_bad(pmd_t *pmd)
 682 {
 683         pmd_t pmdval = pmd_read_atomic(pmd);
 684         /*
 685          * The barrier will stabilize the pmdval in a register or on
 686          * the stack so that it will stop changing under the code.
 687          *
 688          * When CONFIG_TRANSPARENT_HUGEPAGE=y on x86 32bit PAE,
 689          * pmd_read_atomic is allowed to return a not atomic pmdval
 690          * (for example pointing to an hugepage that has never been
 691          * mapped in the pmd). The below checks will only care about
 692          * the low part of the pmd with 32bit PAE x86 anyway, with the
 693          * exception of pmd_none(). So the important thing is that if
 694          * the low part of the pmd is found null, the high part will
 695          * be also null or the pmd_none() check below would be
 696          * confused.
 697          */
 698 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 699         barrier();
 700 #endif
 701         if (pmd_none(pmdval) || pmd_trans_huge(pmdval))
 702                 return 1;
 703         if (unlikely(pmd_bad(pmdval))) {
 704                 pmd_clear_bad(pmd);
 705                 return 1;
 706         }
 707         return 0;
 708 }
 709
 710 /*
 711  * This is a noop if Transparent Hugepage Support is not built into
 712  * the kernel. Otherwise it is equivalent to
 713  * pmd_none_or_trans_huge_or_clear_bad(), and shall only be called in
 714  * places that already verified the pmd is not none and they want to
 715  * walk ptes while holding the mmap sem in read mode (write mode don't
 716  * need this). If THP is not enabled, the pmd can't go away under the
 717  * code even if MADV_DONTNEED runs, but if THP is enabled we need to
 718  * run a pmd_trans_unstable before walking the ptes after
 719  * split_huge_page_pmd returns (because it may have run when the pmd
 720  * become null, but then a page fault can map in a THP and not a
 721  * regular page).
 722  */
 723 static inline int pmd_trans_unstable(pmd_t *pmd)
 724 {
 725 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 726         return pmd_none_or_trans_huge_or_clear_bad(pmd);
 727 #else
 728         return 0;
 729 #endif
 730 }
 731
 732 #ifndef CONFIG_NUMA_BALANCING
 733 /*
 734  * Technically a PTE can be PROTNONE even when not doing NUMA balancing but
 735  * the only case the kernel cares is for NUMA balancing and is only ever set
 736  * when the VMA is accessible. For PROT_NONE VMAs, the PTEs are not marked
 737  * _PAGE_PROTNONE so by by default, implement the helper as "always no". It
 738  * is the responsibility of the caller to distinguish between PROT_NONE
 739  * protections and NUMA hinting fault protections.
 740  */
 741 static inline int pte_protnone(pte_t pte)
 742 {
 743         return 0;
 744 }
 745
 746 static inline int pmd_protnone(pmd_t pmd)
 747 {
 748         return 0;
 749 }
 750 #endif /* CONFIG_NUMA_BALANCING */
 751
 752 #endif /* CONFIG_MMU */
 753
 754 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 755 int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot);
 756 int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot);
 757 int pud_clear_huge(pud_t *pud);
 758 int pmd_clear_huge(pmd_t *pmd);
 759 #else   /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
 760 static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
 761 {
 762         return 0;
 763 }
 764 static inline int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
 765 {
 766         return 0;
 767 }
 768 static inline int pud_clear_huge(pud_t *pud)
 769 {
 770         return 0;
 771 }
 772 static inline int pmd_clear_huge(pmd_t *pmd)
 773 {
 774         return 0;
 775 }
 776 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
 777
 778 #endif /* !__ASSEMBLY__ */
 779
 780 #ifndef io_remap_pfn_range
 781 #define io_remap_pfn_range remap_pfn_range
 782 #endif
 783
 784 #endif /* _ASM_GENERIC_PGTABLE_H */