arch/x86/mm/pgtable.c

   1 #include <linux/mm.h>
   2 #include <linux/gfp.h>
   3 #include <asm/pgalloc.h>
   4 #include <asm/pgtable.h>
   5 #include <asm/tlb.h>
   6 #include <asm/fixmap.h>
   7 #include <asm/mtrr.h>
   8
   9 #define PGALLOC_GFP (GFP_KERNEL_ACCOUNT | __GFP_NOTRACK | __GFP_ZERO)
  10
  11 #ifdef CONFIG_HIGHPTE
  12 #define PGALLOC_USER_GFP __GFP_HIGHMEM
  13 #else
  14 #define PGALLOC_USER_GFP 0
  15 #endif
  16
  17 gfp_t __userpte_alloc_gfp = PGALLOC_GFP | PGALLOC_USER_GFP;
  18
  19 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
  20 {
  21         return (pte_t *)__get_free_page(PGALLOC_GFP & ~__GFP_ACCOUNT);
  22 }
  23
  24 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
  25 {
  26         struct page *pte;
  27
  28         pte = alloc_pages(__userpte_alloc_gfp, 0);
  29         if (!pte)
  30                 return NULL;
  31         if (!pgtable_page_ctor(pte)) {
  32                 __free_page(pte);
  33                 return NULL;
  34         }
  35         return pte;
  36 }
  37
  38 static int __init setup_userpte(char *arg)
  39 {
  40         if (!arg)
  41                 return -EINVAL;
  42
  43         /*
  44          * "userpte=nohigh" disables allocation of user pagetables in
  45          * high memory.
  46          */
  47         if (strcmp(arg, "nohigh") == 0)
  48                 __userpte_alloc_gfp &= ~__GFP_HIGHMEM;
  49         else
  50                 return -EINVAL;
  51         return 0;
  52 }
  53 early_param("userpte", setup_userpte);
  54
  55 void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
  56 {
  57         pgtable_page_dtor(pte);
  58         paravirt_release_pte(page_to_pfn(pte));
  59         tlb_remove_table(tlb, pte);
  60 }
  61
  62 #if CONFIG_PGTABLE_LEVELS > 2
  63 void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
  64 {
  65         struct page *page = virt_to_page(pmd);
  66         paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
  67         /*
  68          * NOTE! For PAE, any changes to the top page-directory-pointer-table
  69          * entries need a full cr3 reload to flush.
  70          */
  71 #ifdef CONFIG_X86_PAE
  72         tlb->need_flush_all = 1;
  73 #endif
  74         pgtable_pmd_page_dtor(page);
  75         tlb_remove_table(tlb, page);
  76 }
  77
  78 #if CONFIG_PGTABLE_LEVELS > 3
  79 void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
  80 {
  81         paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
  82         tlb_remove_table(tlb, virt_to_page(pud));
  83 }
  84
  85 #if CONFIG_PGTABLE_LEVELS > 4
  86 void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
  87 {
  88         paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
  89         tlb_remove_table(tlb, virt_to_page(p4d));
  90 }
  91 #endif  /* CONFIG_PGTABLE_LEVELS > 4 */
  92 #endif  /* CONFIG_PGTABLE_LEVELS > 3 */
  93 #endif  /* CONFIG_PGTABLE_LEVELS > 2 */
  94
  95 static inline void pgd_list_add(pgd_t *pgd)
  96 {
  97         struct page *page = virt_to_page(pgd);
  98
  99         list_add(&page->lru, &pgd_list);
 100 }
 101
 102 static inline void pgd_list_del(pgd_t *pgd)
 103 {
 104         struct page *page = virt_to_page(pgd);
 105
 106         list_del(&page->lru);
 107 }
 108
 109 #define UNSHARED_PTRS_PER_PGD                           \
 110         (SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
 111
 112
 113 static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
 114 {
 115         BUILD_BUG_ON(sizeof(virt_to_page(pgd)->index) < sizeof(mm));
 116         virt_to_page(pgd)->index = (pgoff_t)mm;
 117 }
 118
 119 struct mm_struct *pgd_page_get_mm(struct page *page)
 120 {
 121         return (struct mm_struct *)page->index;
 122 }
 123
 124 static void pgd_ctor(struct mm_struct *mm, pgd_t *pgd)
 125 {
 126         /* If the pgd points to a shared pagetable level (either the
 127            ptes in non-PAE, or shared PMD in PAE), then just copy the
 128            references from swapper_pg_dir. */
 129         if (CONFIG_PGTABLE_LEVELS == 2 ||
 130             (CONFIG_PGTABLE_LEVELS == 3 && SHARED_KERNEL_PMD) ||
 131             CONFIG_PGTABLE_LEVELS >= 4) {
 132                 clone_pgd_range(pgd + KERNEL_PGD_BOUNDARY,
 133                                 swapper_pg_dir + KERNEL_PGD_BOUNDARY,
 134                                 KERNEL_PGD_PTRS);
 135         }
 136
 137         /* list required to sync kernel mapping updates */
 138         if (!SHARED_KERNEL_PMD) {
 139                 pgd_set_mm(pgd, mm);
 140                 pgd_list_add(pgd);
 141         }
 142 }
 143
 144 static void pgd_dtor(pgd_t *pgd)
 145 {
 146         if (SHARED_KERNEL_PMD)
 147                 return;
 148
 149         spin_lock(&pgd_lock);
 150         pgd_list_del(pgd);
 151         spin_unlock(&pgd_lock);
 152 }
 153
 154 /*
 155  * List of all pgd's needed for non-PAE so it can invalidate entries
 156  * in both cached and uncached pgd's; not needed for PAE since the
 157  * kernel pmd is shared. If PAE were not to share the pmd a similar
 158  * tactic would be needed. This is essentially codepath-based locking
 159  * against pageattr.c; it is the unique case in which a valid change
 160  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 161  * vmalloc faults work because attached pagetables are never freed.
 162  * -- nyc
 163  */
 164
 165 #ifdef CONFIG_X86_PAE
 166 /*
 167  * In PAE mode, we need to do a cr3 reload (=tlb flush) when
 168  * updating the top-level pagetable entries to guarantee the
 169  * processor notices the update.  Since this is expensive, and
 170  * all 4 top-level entries are used almost immediately in a
 171  * new process's life, we just pre-populate them here.
 172  *
 173  * Also, if we're in a paravirt environment where the kernel pmd is
 174  * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
 175  * and initialize the kernel pmds here.
 176  */
 177 #define PREALLOCATED_PMDS       UNSHARED_PTRS_PER_PGD
 178
 179 void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
 180 {
 181         paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
 182
 183         /* Note: almost everything apart from _PAGE_PRESENT is
 184            reserved at the pmd (PDPT) level. */
 185         set_pud(pudp, __pud(__pa(pmd) | _PAGE_PRESENT));
 186
 187         /*
 188          * According to Intel App note "TLBs, Paging-Structure Caches,
 189          * and Their Invalidation", April 2007, document 317080-001,
 190          * section 8.1: in PAE mode we explicitly have to flush the
 191          * TLB via cr3 if the top-level pgd is changed...
 192          */
 193         flush_tlb_mm(mm);
 194 }
 195 #else  /* !CONFIG_X86_PAE */
 196
 197 /* No need to prepopulate any pagetable entries in non-PAE modes. */
 198 #define PREALLOCATED_PMDS       0
 199
 200 #endif  /* CONFIG_X86_PAE */
 201
 202 static void free_pmds(struct mm_struct *mm, pmd_t *pmds[])
 203 {
 204         int i;
 205
 206         for(i = 0; i < PREALLOCATED_PMDS; i++)
 207                 if (pmds[i]) {
 208                         pgtable_pmd_page_dtor(virt_to_page(pmds[i]));
 209                         free_page((unsigned long)pmds[i]);
 210                         mm_dec_nr_pmds(mm);
 211                 }
 212 }
 213
 214 static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[])
 215 {
 216         int i;
 217         bool failed = false;
 218         gfp_t gfp = PGALLOC_GFP;
 219
 220         if (mm == &init_mm)
 221                 gfp &= ~__GFP_ACCOUNT;
 222
 223         for(i = 0; i < PREALLOCATED_PMDS; i++) {
 224                 pmd_t *pmd = (pmd_t *)__get_free_page(gfp);
 225                 if (!pmd)
 226                         failed = true;
 227                 if (pmd && !pgtable_pmd_page_ctor(virt_to_page(pmd))) {
 228                         free_page((unsigned long)pmd);
 229                         pmd = NULL;
 230                         failed = true;
 231                 }
 232                 if (pmd)
 233                         mm_inc_nr_pmds(mm);
 234                 pmds[i] = pmd;
 235         }
 236
 237         if (failed) {
 238                 free_pmds(mm, pmds);
 239                 return -ENOMEM;
 240         }
 241
 242         return 0;
 243 }
 244
 245 /*
 246  * Mop up any pmd pages which may still be attached to the pgd.
 247  * Normally they will be freed by munmap/exit_mmap, but any pmd we
 248  * preallocate which never got a corresponding vma will need to be
 249  * freed manually.
 250  */
 251 static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
 252 {
 253         int i;
 254
 255         for(i = 0; i < PREALLOCATED_PMDS; i++) {
 256                 pgd_t pgd = pgdp[i];
 257
 258                 if (pgd_val(pgd) != 0) {
 259                         pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
 260
 261                         pgdp[i] = native_make_pgd(0);
 262
 263                         paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT);
 264                         pmd_free(mm, pmd);
 265                         mm_dec_nr_pmds(mm);
 266                 }
 267         }
 268 }
 269
 270 static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
 271 {
 272         p4d_t *p4d;
 273         pud_t *pud;
 274         int i;
 275
 276         if (PREALLOCATED_PMDS == 0) /* Work around gcc-3.4.x bug */
 277                 return;
 278
 279         p4d = p4d_offset(pgd, 0);
 280         pud = pud_offset(p4d, 0);
 281
 282         for (i = 0; i < PREALLOCATED_PMDS; i++, pud++) {
 283                 pmd_t *pmd = pmds[i];
 284
 285                 if (i >= KERNEL_PGD_BOUNDARY)
 286                         memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
 287                                sizeof(pmd_t) * PTRS_PER_PMD);
 288
 289                 pud_populate(mm, pud, pmd);
 290         }
 291 }
 292
 293 /*
 294  * Xen paravirt assumes pgd table should be in one page. 64 bit kernel also
 295  * assumes that pgd should be in one page.
 296  *
 297  * But kernel with PAE paging that is not running as a Xen domain
 298  * only needs to allocate 32 bytes for pgd instead of one page.
 299  */
 300 #ifdef CONFIG_X86_PAE
 301
 302 #include <linux/slab.h>
 303
 304 #define PGD_SIZE        (PTRS_PER_PGD * sizeof(pgd_t))
 305 #define PGD_ALIGN       32
 306
 307 static struct kmem_cache *pgd_cache;
 308
 309 static int __init pgd_cache_init(void)
 310 {
 311         /*
 312          * When PAE kernel is running as a Xen domain, it does not use
 313          * shared kernel pmd. And this requires a whole page for pgd.
 314          */
 315         if (!SHARED_KERNEL_PMD)
 316                 return 0;
 317
 318         /*
 319          * when PAE kernel is not running as a Xen domain, it uses
 320          * shared kernel pmd. Shared kernel pmd does not require a whole
 321          * page for pgd. We are able to just allocate a 32-byte for pgd.
 322          * During boot time, we create a 32-byte slab for pgd table allocation.
 323          */
 324         pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_ALIGN,
 325                                       SLAB_PANIC, NULL);
 326         if (!pgd_cache)
 327                 return -ENOMEM;
 328
 329         return 0;
 330 }
 331 core_initcall(pgd_cache_init);
 332
 333 static inline pgd_t *_pgd_alloc(void)
 334 {
 335         /*
 336          * If no SHARED_KERNEL_PMD, PAE kernel is running as a Xen domain.
 337          * We allocate one page for pgd.
 338          */
 339         if (!SHARED_KERNEL_PMD)
 340                 return (pgd_t *)__get_free_page(PGALLOC_GFP);
 341
 342         /*
 343          * Now PAE kernel is not running as a Xen domain. We can allocate
 344          * a 32-byte slab for pgd to save memory space.
 345          */
 346         return kmem_cache_alloc(pgd_cache, PGALLOC_GFP);
 347 }
 348
 349 static inline void _pgd_free(pgd_t *pgd)
 350 {
 351         if (!SHARED_KERNEL_PMD)
 352                 free_page((unsigned long)pgd);
 353         else
 354                 kmem_cache_free(pgd_cache, pgd);
 355 }
 356 #else
 357 static inline pgd_t *_pgd_alloc(void)
 358 {
 359         return (pgd_t *)__get_free_page(PGALLOC_GFP);
 360 }
 361
 362 static inline void _pgd_free(pgd_t *pgd)
 363 {
 364         free_page((unsigned long)pgd);
 365 }
 366 #endif /* CONFIG_X86_PAE */
 367
 368 pgd_t *pgd_alloc(struct mm_struct *mm)
 369 {
 370         pgd_t *pgd;
 371         pmd_t *pmds[PREALLOCATED_PMDS];
 372
 373         pgd = _pgd_alloc();
 374
 375         if (pgd == NULL)
 376                 goto out;
 377
 378         mm->pgd = pgd;
 379
 380         if (preallocate_pmds(mm, pmds) != 0)
 381                 goto out_free_pgd;
 382
 383         if (paravirt_pgd_alloc(mm) != 0)
 384                 goto out_free_pmds;
 385
 386         /*
 387          * Make sure that pre-populating the pmds is atomic with
 388          * respect to anything walking the pgd_list, so that they
 389          * never see a partially populated pgd.
 390          */
 391         spin_lock(&pgd_lock);
 392
 393         pgd_ctor(mm, pgd);
 394         pgd_prepopulate_pmd(mm, pgd, pmds);
 395
 396         spin_unlock(&pgd_lock);
 397
 398         return pgd;
 399
 400 out_free_pmds:
 401         free_pmds(mm, pmds);
 402 out_free_pgd:
 403         _pgd_free(pgd);
 404 out:
 405         return NULL;
 406 }
 407
 408 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 409 {
 410         pgd_mop_up_pmds(mm, pgd);
 411         pgd_dtor(pgd);
 412         paravirt_pgd_free(mm, pgd);
 413         _pgd_free(pgd);
 414 }
 415
 416 /*
 417  * Used to set accessed or dirty bits in the page table entries
 418  * on other architectures. On x86, the accessed and dirty bits
 419  * are tracked by hardware. However, do_wp_page calls this function
 420  * to also make the pte writeable at the same time the dirty bit is
 421  * set. In that case we do actually need to write the PTE.
 422  */
 423 int ptep_set_access_flags(struct vm_area_struct *vma,
 424                           unsigned long address, pte_t *ptep,
 425                           pte_t entry, int dirty)
 426 {
 427         int changed = !pte_same(*ptep, entry);
 428
 429         if (changed && dirty) {
 430                 *ptep = entry;
 431                 pte_update(vma->vm_mm, address, ptep);
 432         }
 433
 434         return changed;
 435 }
 436
 437 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 438 int pmdp_set_access_flags(struct vm_area_struct *vma,
 439                           unsigned long address, pmd_t *pmdp,
 440                           pmd_t entry, int dirty)
 441 {
 442         int changed = !pmd_same(*pmdp, entry);
 443
 444         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 445
 446         if (changed && dirty) {
 447                 *pmdp = entry;
 448                 /*
 449                  * We had a write-protection fault here and changed the pmd
 450                  * to to more permissive. No need to flush the TLB for that,
 451                  * #PF is architecturally guaranteed to do that and in the
 452                  * worst-case we'll generate a spurious fault.
 453                  */
 454         }
 455
 456         return changed;
 457 }
 458
 459 int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
 460                           pud_t *pudp, pud_t entry, int dirty)
 461 {
 462         int changed = !pud_same(*pudp, entry);
 463
 464         VM_BUG_ON(address & ~HPAGE_PUD_MASK);
 465
 466         if (changed && dirty) {
 467                 *pudp = entry;
 468                 /*
 469                  * We had a write-protection fault here and changed the pud
 470                  * to to more permissive. No need to flush the TLB for that,
 471                  * #PF is architecturally guaranteed to do that and in the
 472                  * worst-case we'll generate a spurious fault.
 473                  */
 474         }
 475
 476         return changed;
 477 }
 478 #endif
 479
 480 int ptep_test_and_clear_young(struct vm_area_struct *vma,
 481                               unsigned long addr, pte_t *ptep)
 482 {
 483         int ret = 0;
 484
 485         if (pte_young(*ptep))
 486                 ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
 487                                          (unsigned long *) &ptep->pte);
 488
 489         if (ret)
 490                 pte_update(vma->vm_mm, addr, ptep);
 491
 492         return ret;
 493 }
 494
 495 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 496 int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 497                               unsigned long addr, pmd_t *pmdp)
 498 {
 499         int ret = 0;
 500
 501         if (pmd_young(*pmdp))
 502                 ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
 503                                          (unsigned long *)pmdp);
 504
 505         return ret;
 506 }
 507 int pudp_test_and_clear_young(struct vm_area_struct *vma,
 508                               unsigned long addr, pud_t *pudp)
 509 {
 510         int ret = 0;
 511
 512         if (pud_young(*pudp))
 513                 ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
 514                                          (unsigned long *)pudp);
 515
 516         return ret;
 517 }
 518 #endif
 519
 520 int ptep_clear_flush_young(struct vm_area_struct *vma,
 521                            unsigned long address, pte_t *ptep)
 522 {
 523         /*
 524          * On x86 CPUs, clearing the accessed bit without a TLB flush
 525          * doesn't cause data corruption. [ It could cause incorrect
 526          * page aging and the (mistaken) reclaim of hot pages, but the
 527          * chance of that should be relatively low. ]
 528          *
 529          * So as a performance optimization don't flush the TLB when
 530          * clearing the accessed bit, it will eventually be flushed by
 531          * a context switch or a VM operation anyway. [ In the rare
 532          * event of it not getting flushed for a long time the delay
 533          * shouldn't really matter because there's no real memory
 534          * pressure for swapout to react to. ]
 535          */
 536         return ptep_test_and_clear_young(vma, address, ptep);
 537 }
 538
 539 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 540 int pmdp_clear_flush_young(struct vm_area_struct *vma,
 541                            unsigned long address, pmd_t *pmdp)
 542 {
 543         int young;
 544
 545         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 546
 547         young = pmdp_test_and_clear_young(vma, address, pmdp);
 548         if (young)
 549                 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 550
 551         return young;
 552 }
 553 #endif
 554
 555 /**
 556  * reserve_top_address - reserves a hole in the top of kernel address space
 557  * @reserve - size of hole to reserve
 558  *
 559  * Can be used to relocate the fixmap area and poke a hole in the top
 560  * of kernel address space to make room for a hypervisor.
 561  */
 562 void __init reserve_top_address(unsigned long reserve)
 563 {
 564 #ifdef CONFIG_X86_32
 565         BUG_ON(fixmaps_set > 0);
 566         __FIXADDR_TOP = round_down(-reserve, 1 << PMD_SHIFT) - PAGE_SIZE;
 567         printk(KERN_INFO "Reserving virtual address space above 0x%08lx (rounded to 0x%08lx)\n",
 568                -reserve, __FIXADDR_TOP + PAGE_SIZE);
 569 #endif
 570 }
 571
 572 int fixmaps_set;
 573
 574 void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
 575 {
 576         unsigned long address = __fix_to_virt(idx);
 577
 578         if (idx >= __end_of_fixed_addresses) {
 579                 BUG();
 580                 return;
 581         }
 582         set_pte_vaddr(address, pte);
 583         fixmaps_set++;
 584 }
 585
 586 void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys,
 587                        pgprot_t flags)
 588 {
 589         __native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
 590 }
 591
 592 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 593 #ifdef CONFIG_X86_5LEVEL
 594 /**
 595  * p4d_set_huge - setup kernel P4D mapping
 596  *
 597  * No 512GB pages yet -- always return 0
 598  */
 599 int p4d_set_huge(p4d_t *p4d, phys_addr_t addr, pgprot_t prot)
 600 {
 601         return 0;
 602 }
 603
 604 /**
 605  * p4d_clear_huge - clear kernel P4D mapping when it is set
 606  *
 607  * No 512GB pages yet -- always return 0
 608  */
 609 int p4d_clear_huge(p4d_t *p4d)
 610 {
 611         return 0;
 612 }
 613 #endif
 614
 615 /**
 616  * pud_set_huge - setup kernel PUD mapping
 617  *
 618  * MTRRs can override PAT memory types with 4KiB granularity. Therefore, this
 619  * function sets up a huge page only if any of the following conditions are met:
 620  *
 621  * - MTRRs are disabled, or
 622  *
 623  * - MTRRs are enabled and the range is completely covered by a single MTRR, or
 624  *
 625  * - MTRRs are enabled and the corresponding MTRR memory type is WB, which
 626  *   has no effect on the requested PAT memory type.
 627  *
 628  * Callers should try to decrease page size (1GB -> 2MB -> 4K) if the bigger
 629  * page mapping attempt fails.
 630  *
 631  * Returns 1 on success and 0 on failure.
 632  */
 633 int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
 634 {
 635         u8 mtrr, uniform;
 636
 637         mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform);
 638         if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
 639             (mtrr != MTRR_TYPE_WRBACK))
 640                 return 0;
 641
 642         prot = pgprot_4k_2_large(prot);
 643
 644         set_pte((pte_t *)pud, pfn_pte(
 645                 (u64)addr >> PAGE_SHIFT,
 646                 __pgprot(pgprot_val(prot) | _PAGE_PSE)));
 647
 648         return 1;
 649 }
 650
 651 /**
 652  * pmd_set_huge - setup kernel PMD mapping
 653  *
 654  * See text over pud_set_huge() above.
 655  *
 656  * Returns 1 on success and 0 on failure.
 657  */
 658 int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
 659 {
 660         u8 mtrr, uniform;
 661
 662         mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE, &uniform);
 663         if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
 664             (mtrr != MTRR_TYPE_WRBACK)) {
 665                 pr_warn_once("%s: Cannot satisfy [mem %#010llx-%#010llx] with a huge-page mapping due to MTRR override.\n",
 666                              __func__, addr, addr + PMD_SIZE);
 667                 return 0;
 668         }
 669
 670         prot = pgprot_4k_2_large(prot);
 671
 672         set_pte((pte_t *)pmd, pfn_pte(
 673                 (u64)addr >> PAGE_SHIFT,
 674                 __pgprot(pgprot_val(prot) | _PAGE_PSE)));
 675
 676         return 1;
 677 }
 678
 679 /**
 680  * pud_clear_huge - clear kernel PUD mapping when it is set
 681  *
 682  * Returns 1 on success and 0 on failure (no PUD map is found).
 683  */
 684 int pud_clear_huge(pud_t *pud)
 685 {
 686         if (pud_large(*pud)) {
 687                 pud_clear(pud);
 688                 return 1;
 689         }
 690
 691         return 0;
 692 }
 693
 694 /**
 695  * pmd_clear_huge - clear kernel PMD mapping when it is set
 696  *
 697  * Returns 1 on success and 0 on failure (no PMD map is found).
 698  */
 699 int pmd_clear_huge(pmd_t *pmd)
 700 {
 701         if (pmd_large(*pmd)) {
 702                 pmd_clear(pmd);
 703                 return 1;
 704         }
 705
 706         return 0;
 707 }
 708 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */