arch/x86/mm/pgtable.c

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This source file includes following definitions.
pte_alloc_one
setup_userpte
___pte_free_tlb
___pmd_free_tlb
___pud_free_tlb
___p4d_free_tlb
pgd_list_add
pgd_list_del
pgd_set_mm
pgd_page_get_mm
pgd_ctor
pgd_dtor
pud_populate
free_pmds
preallocate_pmds
mop_up_one_pmd
pgd_mop_up_pmds
pgd_prepopulate_pmd
pgd_prepopulate_user_pmd
pgd_prepopulate_user_pmd
pgtable_cache_init
_pgd_alloc
_pgd_free
_pgd_alloc
_pgd_free
pgd_alloc
pgd_free
ptep_set_access_flags
pmdp_set_access_flags
pudp_set_access_flags
ptep_test_and_clear_young
pmdp_test_and_clear_young
pudp_test_and_clear_young
ptep_clear_flush_young
pmdp_clear_flush_young
reserve_top_address
__native_set_fixmap
native_set_fixmap
p4d_set_huge
p4d_clear_huge
pud_set_huge
pmd_set_huge
pud_clear_huge
pmd_clear_huge
p4d_free_pud_page
pud_free_pmd_page
pmd_free_pte_page
pud_free_pmd_page
pmd_free_pte_page
   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/mm.h>
   3 #include <linux/gfp.h>
   4 #include <linux/hugetlb.h>
   5 #include <asm/pgalloc.h>
   6 #include <asm/pgtable.h>
   7 #include <asm/tlb.h>
   8 #include <asm/fixmap.h>
   9 #include <asm/mtrr.h>
  10 
  11 #ifdef CONFIG_DYNAMIC_PHYSICAL_MASK
  12 phys_addr_t physical_mask __ro_after_init = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
  13 EXPORT_SYMBOL(physical_mask);
  14 #endif
  15 
  16 #ifdef CONFIG_HIGHPTE
  17 #define PGTABLE_HIGHMEM __GFP_HIGHMEM
  18 #else
  19 #define PGTABLE_HIGHMEM 0
  20 #endif
  21 
  22 gfp_t __userpte_alloc_gfp = GFP_PGTABLE_USER | PGTABLE_HIGHMEM;
  23 
  24 pgtable_t pte_alloc_one(struct mm_struct *mm)
  25 {
  26         return __pte_alloc_one(mm, __userpte_alloc_gfp);
  27 }
  28 
  29 static int __init setup_userpte(char *arg)
  30 {
  31         if (!arg)
  32                 return -EINVAL;
  33 
  34         /*
  35          * "userpte=nohigh" disables allocation of user pagetables in
  36          * high memory.
  37          */
  38         if (strcmp(arg, "nohigh") == 0)
  39                 __userpte_alloc_gfp &= ~__GFP_HIGHMEM;
  40         else
  41                 return -EINVAL;
  42         return 0;
  43 }
  44 early_param("userpte", setup_userpte);
  45 
  46 void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
  47 {
  48         pgtable_pte_page_dtor(pte);
  49         paravirt_release_pte(page_to_pfn(pte));
  50         paravirt_tlb_remove_table(tlb, pte);
  51 }
  52 
  53 #if CONFIG_PGTABLE_LEVELS > 2
  54 void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
  55 {
  56         struct page *page = virt_to_page(pmd);
  57         paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
  58         /*
  59          * NOTE! For PAE, any changes to the top page-directory-pointer-table
  60          * entries need a full cr3 reload to flush.
  61          */
  62 #ifdef CONFIG_X86_PAE
  63         tlb->need_flush_all = 1;
  64 #endif
  65         pgtable_pmd_page_dtor(page);
  66         paravirt_tlb_remove_table(tlb, page);
  67 }
  68 
  69 #if CONFIG_PGTABLE_LEVELS > 3
  70 void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
  71 {
  72         paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
  73         paravirt_tlb_remove_table(tlb, virt_to_page(pud));
  74 }
  75 
  76 #if CONFIG_PGTABLE_LEVELS > 4
  77 void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
  78 {
  79         paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
  80         paravirt_tlb_remove_table(tlb, virt_to_page(p4d));
  81 }
  82 #endif  /* CONFIG_PGTABLE_LEVELS > 4 */
  83 #endif  /* CONFIG_PGTABLE_LEVELS > 3 */
  84 #endif  /* CONFIG_PGTABLE_LEVELS > 2 */
  85 
  86 static inline void pgd_list_add(pgd_t *pgd)
  87 {
  88         struct page *page = virt_to_page(pgd);
  89 
  90         list_add(&page->lru, &pgd_list);
  91 }
  92 
  93 static inline void pgd_list_del(pgd_t *pgd)
  94 {
  95         struct page *page = virt_to_page(pgd);
  96 
  97         list_del(&page->lru);
  98 }
  99 
 100 #define UNSHARED_PTRS_PER_PGD                           \
 101         (SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
 102 #define MAX_UNSHARED_PTRS_PER_PGD                       \
 103         max_t(size_t, KERNEL_PGD_BOUNDARY, PTRS_PER_PGD)
 104 
 105 
 106 static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
 107 {
 108         virt_to_page(pgd)->pt_mm = mm;
 109 }
 110 
 111 struct mm_struct *pgd_page_get_mm(struct page *page)
 112 {
 113         return page->pt_mm;
 114 }
 115 
 116 static void pgd_ctor(struct mm_struct *mm, pgd_t *pgd)
 117 {
 118         /* If the pgd points to a shared pagetable level (either the
 119            ptes in non-PAE, or shared PMD in PAE), then just copy the
 120            references from swapper_pg_dir. */
 121         if (CONFIG_PGTABLE_LEVELS == 2 ||
 122             (CONFIG_PGTABLE_LEVELS == 3 && SHARED_KERNEL_PMD) ||
 123             CONFIG_PGTABLE_LEVELS >= 4) {
 124                 clone_pgd_range(pgd + KERNEL_PGD_BOUNDARY,
 125                                 swapper_pg_dir + KERNEL_PGD_BOUNDARY,
 126                                 KERNEL_PGD_PTRS);
 127         }
 128 
 129         /* list required to sync kernel mapping updates */
 130         if (!SHARED_KERNEL_PMD) {
 131                 pgd_set_mm(pgd, mm);
 132                 pgd_list_add(pgd);
 133         }
 134 }
 135 
 136 static void pgd_dtor(pgd_t *pgd)
 137 {
 138         if (SHARED_KERNEL_PMD)
 139                 return;
 140 
 141         spin_lock(&pgd_lock);
 142         pgd_list_del(pgd);
 143         spin_unlock(&pgd_lock);
 144 }
 145 
 146 /*
 147  * List of all pgd's needed for non-PAE so it can invalidate entries
 148  * in both cached and uncached pgd's; not needed for PAE since the
 149  * kernel pmd is shared. If PAE were not to share the pmd a similar
 150  * tactic would be needed. This is essentially codepath-based locking
 151  * against pageattr.c; it is the unique case in which a valid change
 152  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 153  * vmalloc faults work because attached pagetables are never freed.
 154  * -- nyc
 155  */
 156 
 157 #ifdef CONFIG_X86_PAE
 158 /*
 159  * In PAE mode, we need to do a cr3 reload (=tlb flush) when
 160  * updating the top-level pagetable entries to guarantee the
 161  * processor notices the update.  Since this is expensive, and
 162  * all 4 top-level entries are used almost immediately in a
 163  * new process's life, we just pre-populate them here.
 164  *
 165  * Also, if we're in a paravirt environment where the kernel pmd is
 166  * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
 167  * and initialize the kernel pmds here.
 168  */
 169 #define PREALLOCATED_PMDS       UNSHARED_PTRS_PER_PGD
 170 #define MAX_PREALLOCATED_PMDS   MAX_UNSHARED_PTRS_PER_PGD
 171 
 172 /*
 173  * We allocate separate PMDs for the kernel part of the user page-table
 174  * when PTI is enabled. We need them to map the per-process LDT into the
 175  * user-space page-table.
 176  */
 177 #define PREALLOCATED_USER_PMDS   (boot_cpu_has(X86_FEATURE_PTI) ? \
 178                                         KERNEL_PGD_PTRS : 0)
 179 #define MAX_PREALLOCATED_USER_PMDS KERNEL_PGD_PTRS
 180 
 181 void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
 182 {
 183         paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
 184 
 185         /* Note: almost everything apart from _PAGE_PRESENT is
 186            reserved at the pmd (PDPT) level. */
 187         set_pud(pudp, __pud(__pa(pmd) | _PAGE_PRESENT));
 188 
 189         /*
 190          * According to Intel App note "TLBs, Paging-Structure Caches,
 191          * and Their Invalidation", April 2007, document 317080-001,
 192          * section 8.1: in PAE mode we explicitly have to flush the
 193          * TLB via cr3 if the top-level pgd is changed...
 194          */
 195         flush_tlb_mm(mm);
 196 }
 197 #else  /* !CONFIG_X86_PAE */
 198 
 199 /* No need to prepopulate any pagetable entries in non-PAE modes. */
 200 #define PREALLOCATED_PMDS       0
 201 #define MAX_PREALLOCATED_PMDS   0
 202 #define PREALLOCATED_USER_PMDS   0
 203 #define MAX_PREALLOCATED_USER_PMDS 0
 204 #endif  /* CONFIG_X86_PAE */
 205 
 206 static void free_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
 207 {
 208         int i;
 209 
 210         for (i = 0; i < count; i++)
 211                 if (pmds[i]) {
 212                         pgtable_pmd_page_dtor(virt_to_page(pmds[i]));
 213                         free_page((unsigned long)pmds[i]);
 214                         mm_dec_nr_pmds(mm);
 215                 }
 216 }
 217 
 218 static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
 219 {
 220         int i;
 221         bool failed = false;
 222         gfp_t gfp = GFP_PGTABLE_USER;
 223 
 224         if (mm == &init_mm)
 225                 gfp &= ~__GFP_ACCOUNT;
 226 
 227         for (i = 0; i < count; i++) {
 228                 pmd_t *pmd = (pmd_t *)__get_free_page(gfp);
 229                 if (!pmd)
 230                         failed = true;
 231                 if (pmd && !pgtable_pmd_page_ctor(virt_to_page(pmd))) {
 232                         free_page((unsigned long)pmd);
 233                         pmd = NULL;
 234                         failed = true;
 235                 }
 236                 if (pmd)
 237                         mm_inc_nr_pmds(mm);
 238                 pmds[i] = pmd;
 239         }
 240 
 241         if (failed) {
 242                 free_pmds(mm, pmds, count);
 243                 return -ENOMEM;
 244         }
 245 
 246         return 0;
 247 }
 248 
 249 /*
 250  * Mop up any pmd pages which may still be attached to the pgd.
 251  * Normally they will be freed by munmap/exit_mmap, but any pmd we
 252  * preallocate which never got a corresponding vma will need to be
 253  * freed manually.
 254  */
 255 static void mop_up_one_pmd(struct mm_struct *mm, pgd_t *pgdp)
 256 {
 257         pgd_t pgd = *pgdp;
 258 
 259         if (pgd_val(pgd) != 0) {
 260                 pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
 261 
 262                 pgd_clear(pgdp);
 263 
 264                 paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT);
 265                 pmd_free(mm, pmd);
 266                 mm_dec_nr_pmds(mm);
 267         }
 268 }
 269 
 270 static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
 271 {
 272         int i;
 273 
 274         for (i = 0; i < PREALLOCATED_PMDS; i++)
 275                 mop_up_one_pmd(mm, &pgdp[i]);
 276 
 277 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 278 
 279         if (!boot_cpu_has(X86_FEATURE_PTI))
 280                 return;
 281 
 282         pgdp = kernel_to_user_pgdp(pgdp);
 283 
 284         for (i = 0; i < PREALLOCATED_USER_PMDS; i++)
 285                 mop_up_one_pmd(mm, &pgdp[i + KERNEL_PGD_BOUNDARY]);
 286 #endif
 287 }
 288 
 289 static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
 290 {
 291         p4d_t *p4d;
 292         pud_t *pud;
 293         int i;
 294 
 295         if (PREALLOCATED_PMDS == 0) /* Work around gcc-3.4.x bug */
 296                 return;
 297 
 298         p4d = p4d_offset(pgd, 0);
 299         pud = pud_offset(p4d, 0);
 300 
 301         for (i = 0; i < PREALLOCATED_PMDS; i++, pud++) {
 302                 pmd_t *pmd = pmds[i];
 303 
 304                 if (i >= KERNEL_PGD_BOUNDARY)
 305                         memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
 306                                sizeof(pmd_t) * PTRS_PER_PMD);
 307 
 308                 pud_populate(mm, pud, pmd);
 309         }
 310 }
 311 
 312 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 313 static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
 314                                      pgd_t *k_pgd, pmd_t *pmds[])
 315 {
 316         pgd_t *s_pgd = kernel_to_user_pgdp(swapper_pg_dir);
 317         pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd);
 318         p4d_t *u_p4d;
 319         pud_t *u_pud;
 320         int i;
 321 
 322         u_p4d = p4d_offset(u_pgd, 0);
 323         u_pud = pud_offset(u_p4d, 0);
 324 
 325         s_pgd += KERNEL_PGD_BOUNDARY;
 326         u_pud += KERNEL_PGD_BOUNDARY;
 327 
 328         for (i = 0; i < PREALLOCATED_USER_PMDS; i++, u_pud++, s_pgd++) {
 329                 pmd_t *pmd = pmds[i];
 330 
 331                 memcpy(pmd, (pmd_t *)pgd_page_vaddr(*s_pgd),
 332                        sizeof(pmd_t) * PTRS_PER_PMD);
 333 
 334                 pud_populate(mm, u_pud, pmd);
 335         }
 336 
 337 }
 338 #else
 339 static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
 340                                      pgd_t *k_pgd, pmd_t *pmds[])
 341 {
 342 }
 343 #endif
 344 /*
 345  * Xen paravirt assumes pgd table should be in one page. 64 bit kernel also
 346  * assumes that pgd should be in one page.
 347  *
 348  * But kernel with PAE paging that is not running as a Xen domain
 349  * only needs to allocate 32 bytes for pgd instead of one page.
 350  */
 351 #ifdef CONFIG_X86_PAE
 352 
 353 #include <linux/slab.h>
 354 
 355 #define PGD_SIZE        (PTRS_PER_PGD * sizeof(pgd_t))
 356 #define PGD_ALIGN       32
 357 
 358 static struct kmem_cache *pgd_cache;
 359 
 360 void __init pgtable_cache_init(void)
 361 {
 362         /*
 363          * When PAE kernel is running as a Xen domain, it does not use
 364          * shared kernel pmd. And this requires a whole page for pgd.
 365          */
 366         if (!SHARED_KERNEL_PMD)
 367                 return;
 368 
 369         /*
 370          * when PAE kernel is not running as a Xen domain, it uses
 371          * shared kernel pmd. Shared kernel pmd does not require a whole
 372          * page for pgd. We are able to just allocate a 32-byte for pgd.
 373          * During boot time, we create a 32-byte slab for pgd table allocation.
 374          */
 375         pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_ALIGN,
 376                                       SLAB_PANIC, NULL);
 377 }
 378 
 379 static inline pgd_t *_pgd_alloc(void)
 380 {
 381         /*
 382          * If no SHARED_KERNEL_PMD, PAE kernel is running as a Xen domain.
 383          * We allocate one page for pgd.
 384          */
 385         if (!SHARED_KERNEL_PMD)
 386                 return (pgd_t *)__get_free_pages(GFP_PGTABLE_USER,
 387                                                  PGD_ALLOCATION_ORDER);
 388 
 389         /*
 390          * Now PAE kernel is not running as a Xen domain. We can allocate
 391          * a 32-byte slab for pgd to save memory space.
 392          */
 393         return kmem_cache_alloc(pgd_cache, GFP_PGTABLE_USER);
 394 }
 395 
 396 static inline void _pgd_free(pgd_t *pgd)
 397 {
 398         if (!SHARED_KERNEL_PMD)
 399                 free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
 400         else
 401                 kmem_cache_free(pgd_cache, pgd);
 402 }
 403 #else
 404 
 405 static inline pgd_t *_pgd_alloc(void)
 406 {
 407         return (pgd_t *)__get_free_pages(GFP_PGTABLE_USER,
 408                                          PGD_ALLOCATION_ORDER);
 409 }
 410 
 411 static inline void _pgd_free(pgd_t *pgd)
 412 {
 413         free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
 414 }
 415 #endif /* CONFIG_X86_PAE */
 416 
 417 pgd_t *pgd_alloc(struct mm_struct *mm)
 418 {
 419         pgd_t *pgd;
 420         pmd_t *u_pmds[MAX_PREALLOCATED_USER_PMDS];
 421         pmd_t *pmds[MAX_PREALLOCATED_PMDS];
 422 
 423         pgd = _pgd_alloc();
 424 
 425         if (pgd == NULL)
 426                 goto out;
 427 
 428         mm->pgd = pgd;
 429 
 430         if (preallocate_pmds(mm, pmds, PREALLOCATED_PMDS) != 0)
 431                 goto out_free_pgd;
 432 
 433         if (preallocate_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS) != 0)
 434                 goto out_free_pmds;
 435 
 436         if (paravirt_pgd_alloc(mm) != 0)
 437                 goto out_free_user_pmds;
 438 
 439         /*
 440          * Make sure that pre-populating the pmds is atomic with
 441          * respect to anything walking the pgd_list, so that they
 442          * never see a partially populated pgd.
 443          */
 444         spin_lock(&pgd_lock);
 445 
 446         pgd_ctor(mm, pgd);
 447         pgd_prepopulate_pmd(mm, pgd, pmds);
 448         pgd_prepopulate_user_pmd(mm, pgd, u_pmds);
 449 
 450         spin_unlock(&pgd_lock);
 451 
 452         return pgd;
 453 
 454 out_free_user_pmds:
 455         free_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS);
 456 out_free_pmds:
 457         free_pmds(mm, pmds, PREALLOCATED_PMDS);
 458 out_free_pgd:
 459         _pgd_free(pgd);
 460 out:
 461         return NULL;
 462 }
 463 
 464 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 465 {
 466         pgd_mop_up_pmds(mm, pgd);
 467         pgd_dtor(pgd);
 468         paravirt_pgd_free(mm, pgd);
 469         _pgd_free(pgd);
 470 }
 471 
 472 /*
 473  * Used to set accessed or dirty bits in the page table entries
 474  * on other architectures. On x86, the accessed and dirty bits
 475  * are tracked by hardware. However, do_wp_page calls this function
 476  * to also make the pte writeable at the same time the dirty bit is
 477  * set. In that case we do actually need to write the PTE.
 478  */
 479 int ptep_set_access_flags(struct vm_area_struct *vma,
 480                           unsigned long address, pte_t *ptep,
 481                           pte_t entry, int dirty)
 482 {
 483         int changed = !pte_same(*ptep, entry);
 484 
 485         if (changed && dirty)
 486                 set_pte(ptep, entry);
 487 
 488         return changed;
 489 }
 490 
 491 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 492 int pmdp_set_access_flags(struct vm_area_struct *vma,
 493                           unsigned long address, pmd_t *pmdp,
 494                           pmd_t entry, int dirty)
 495 {
 496         int changed = !pmd_same(*pmdp, entry);
 497 
 498         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 499 
 500         if (changed && dirty) {
 501                 set_pmd(pmdp, entry);
 502                 /*
 503                  * We had a write-protection fault here and changed the pmd
 504                  * to to more permissive. No need to flush the TLB for that,
 505                  * #PF is architecturally guaranteed to do that and in the
 506                  * worst-case we'll generate a spurious fault.
 507                  */
 508         }
 509 
 510         return changed;
 511 }
 512 
 513 int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
 514                           pud_t *pudp, pud_t entry, int dirty)
 515 {
 516         int changed = !pud_same(*pudp, entry);
 517 
 518         VM_BUG_ON(address & ~HPAGE_PUD_MASK);
 519 
 520         if (changed && dirty) {
 521                 set_pud(pudp, entry);
 522                 /*
 523                  * We had a write-protection fault here and changed the pud
 524                  * to to more permissive. No need to flush the TLB for that,
 525                  * #PF is architecturally guaranteed to do that and in the
 526                  * worst-case we'll generate a spurious fault.
 527                  */
 528         }
 529 
 530         return changed;
 531 }
 532 #endif
 533 
 534 int ptep_test_and_clear_young(struct vm_area_struct *vma,
 535                               unsigned long addr, pte_t *ptep)
 536 {
 537         int ret = 0;
 538 
 539         if (pte_young(*ptep))
 540                 ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
 541                                          (unsigned long *) &ptep->pte);
 542 
 543         return ret;
 544 }
 545 
 546 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 547 int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 548                               unsigned long addr, pmd_t *pmdp)
 549 {
 550         int ret = 0;
 551 
 552         if (pmd_young(*pmdp))
 553                 ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
 554                                          (unsigned long *)pmdp);
 555 
 556         return ret;
 557 }
 558 int pudp_test_and_clear_young(struct vm_area_struct *vma,
 559                               unsigned long addr, pud_t *pudp)
 560 {
 561         int ret = 0;
 562 
 563         if (pud_young(*pudp))
 564                 ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
 565                                          (unsigned long *)pudp);
 566 
 567         return ret;
 568 }
 569 #endif
 570 
 571 int ptep_clear_flush_young(struct vm_area_struct *vma,
 572                            unsigned long address, pte_t *ptep)
 573 {
 574         /*
 575          * On x86 CPUs, clearing the accessed bit without a TLB flush
 576          * doesn't cause data corruption. [ It could cause incorrect
 577          * page aging and the (mistaken) reclaim of hot pages, but the
 578          * chance of that should be relatively low. ]
 579          *
 580          * So as a performance optimization don't flush the TLB when
 581          * clearing the accessed bit, it will eventually be flushed by
 582          * a context switch or a VM operation anyway. [ In the rare
 583          * event of it not getting flushed for a long time the delay
 584          * shouldn't really matter because there's no real memory
 585          * pressure for swapout to react to. ]
 586          */
 587         return ptep_test_and_clear_young(vma, address, ptep);
 588 }
 589 
 590 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 591 int pmdp_clear_flush_young(struct vm_area_struct *vma,
 592                            unsigned long address, pmd_t *pmdp)
 593 {
 594         int young;
 595 
 596         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 597 
 598         young = pmdp_test_and_clear_young(vma, address, pmdp);
 599         if (young)
 600                 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 601 
 602         return young;
 603 }
 604 #endif
 605 
 606 /**
 607  * reserve_top_address - reserves a hole in the top of kernel address space
 608  * @reserve - size of hole to reserve
 609  *
 610  * Can be used to relocate the fixmap area and poke a hole in the top
 611  * of kernel address space to make room for a hypervisor.
 612  */
 613 void __init reserve_top_address(unsigned long reserve)
 614 {
 615 #ifdef CONFIG_X86_32
 616         BUG_ON(fixmaps_set > 0);
 617         __FIXADDR_TOP = round_down(-reserve, 1 << PMD_SHIFT) - PAGE_SIZE;
 618         printk(KERN_INFO "Reserving virtual address space above 0x%08lx (rounded to 0x%08lx)\n",
 619                -reserve, __FIXADDR_TOP + PAGE_SIZE);
 620 #endif
 621 }
 622 
 623 int fixmaps_set;
 624 
 625 void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
 626 {
 627         unsigned long address = __fix_to_virt(idx);
 628 
 629 #ifdef CONFIG_X86_64
 630        /*
 631         * Ensure that the static initial page tables are covering the
 632         * fixmap completely.
 633         */
 634         BUILD_BUG_ON(__end_of_permanent_fixed_addresses >
 635                      (FIXMAP_PMD_NUM * PTRS_PER_PTE));
 636 #endif
 637 
 638         if (idx >= __end_of_fixed_addresses) {
 639                 BUG();
 640                 return;
 641         }
 642         set_pte_vaddr(address, pte);
 643         fixmaps_set++;
 644 }
 645 
 646 void native_set_fixmap(unsigned /* enum fixed_addresses */ idx,
 647                        phys_addr_t phys, pgprot_t flags)
 648 {
 649         /* Sanitize 'prot' against any unsupported bits: */
 650         pgprot_val(flags) &= __default_kernel_pte_mask;
 651 
 652         __native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
 653 }
 654 
 655 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 656 #ifdef CONFIG_X86_5LEVEL
 657 /**
 658  * p4d_set_huge - setup kernel P4D mapping
 659  *
 660  * No 512GB pages yet -- always return 0
 661  */
 662 int p4d_set_huge(p4d_t *p4d, phys_addr_t addr, pgprot_t prot)
 663 {
 664         return 0;
 665 }
 666 
 667 /**
 668  * p4d_clear_huge - clear kernel P4D mapping when it is set
 669  *
 670  * No 512GB pages yet -- always return 0
 671  */
 672 int p4d_clear_huge(p4d_t *p4d)
 673 {
 674         return 0;
 675 }
 676 #endif
 677 
 678 /**
 679  * pud_set_huge - setup kernel PUD mapping
 680  *
 681  * MTRRs can override PAT memory types with 4KiB granularity. Therefore, this
 682  * function sets up a huge page only if any of the following conditions are met:
 683  *
 684  * - MTRRs are disabled, or
 685  *
 686  * - MTRRs are enabled and the range is completely covered by a single MTRR, or
 687  *
 688  * - MTRRs are enabled and the corresponding MTRR memory type is WB, which
 689  *   has no effect on the requested PAT memory type.
 690  *
 691  * Callers should try to decrease page size (1GB -> 2MB -> 4K) if the bigger
 692  * page mapping attempt fails.
 693  *
 694  * Returns 1 on success and 0 on failure.
 695  */
 696 int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
 697 {
 698         u8 mtrr, uniform;
 699 
 700         mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform);
 701         if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
 702             (mtrr != MTRR_TYPE_WRBACK))
 703                 return 0;
 704 
 705         /* Bail out if we are we on a populated non-leaf entry: */
 706         if (pud_present(*pud) && !pud_huge(*pud))
 707                 return 0;
 708 
 709         prot = pgprot_4k_2_large(prot);
 710 
 711         set_pte((pte_t *)pud, pfn_pte(
 712                 (u64)addr >> PAGE_SHIFT,
 713                 __pgprot(pgprot_val(prot) | _PAGE_PSE)));
 714 
 715         return 1;
 716 }
 717 
 718 /**
 719  * pmd_set_huge - setup kernel PMD mapping
 720  *
 721  * See text over pud_set_huge() above.
 722  *
 723  * Returns 1 on success and 0 on failure.
 724  */
 725 int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
 726 {
 727         u8 mtrr, uniform;
 728 
 729         mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE, &uniform);
 730         if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
 731             (mtrr != MTRR_TYPE_WRBACK)) {
 732                 pr_warn_once("%s: Cannot satisfy [mem %#010llx-%#010llx] with a huge-page mapping due to MTRR override.\n",
 733                              __func__, addr, addr + PMD_SIZE);
 734                 return 0;
 735         }
 736 
 737         /* Bail out if we are we on a populated non-leaf entry: */
 738         if (pmd_present(*pmd) && !pmd_huge(*pmd))
 739                 return 0;
 740 
 741         prot = pgprot_4k_2_large(prot);
 742 
 743         set_pte((pte_t *)pmd, pfn_pte(
 744                 (u64)addr >> PAGE_SHIFT,
 745                 __pgprot(pgprot_val(prot) | _PAGE_PSE)));
 746 
 747         return 1;
 748 }
 749 
 750 /**
 751  * pud_clear_huge - clear kernel PUD mapping when it is set
 752  *
 753  * Returns 1 on success and 0 on failure (no PUD map is found).
 754  */
 755 int pud_clear_huge(pud_t *pud)
 756 {
 757         if (pud_large(*pud)) {
 758                 pud_clear(pud);
 759                 return 1;
 760         }
 761 
 762         return 0;
 763 }
 764 
 765 /**
 766  * pmd_clear_huge - clear kernel PMD mapping when it is set
 767  *
 768  * Returns 1 on success and 0 on failure (no PMD map is found).
 769  */
 770 int pmd_clear_huge(pmd_t *pmd)
 771 {
 772         if (pmd_large(*pmd)) {
 773                 pmd_clear(pmd);
 774                 return 1;
 775         }
 776 
 777         return 0;
 778 }
 779 
 780 /*
 781  * Until we support 512GB pages, skip them in the vmap area.
 782  */
 783 int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
 784 {
 785         return 0;
 786 }
 787 
 788 #ifdef CONFIG_X86_64
 789 /**
 790  * pud_free_pmd_page - Clear pud entry and free pmd page.
 791  * @pud: Pointer to a PUD.
 792  * @addr: Virtual address associated with pud.
 793  *
 794  * Context: The pud range has been unmapped and TLB purged.
 795  * Return: 1 if clearing the entry succeeded. 0 otherwise.
 796  *
 797  * NOTE: Callers must allow a single page allocation.
 798  */
 799 int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 800 {
 801         pmd_t *pmd, *pmd_sv;
 802         pte_t *pte;
 803         int i;
 804 
 805         pmd = (pmd_t *)pud_page_vaddr(*pud);
 806         pmd_sv = (pmd_t *)__get_free_page(GFP_KERNEL);
 807         if (!pmd_sv)
 808                 return 0;
 809 
 810         for (i = 0; i < PTRS_PER_PMD; i++) {
 811                 pmd_sv[i] = pmd[i];
 812                 if (!pmd_none(pmd[i]))
 813                         pmd_clear(&pmd[i]);
 814         }
 815 
 816         pud_clear(pud);
 817 
 818         /* INVLPG to clear all paging-structure caches */
 819         flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
 820 
 821         for (i = 0; i < PTRS_PER_PMD; i++) {
 822                 if (!pmd_none(pmd_sv[i])) {
 823                         pte = (pte_t *)pmd_page_vaddr(pmd_sv[i]);
 824                         free_page((unsigned long)pte);
 825                 }
 826         }
 827 
 828         free_page((unsigned long)pmd_sv);
 829         free_page((unsigned long)pmd);
 830 
 831         return 1;
 832 }
 833 
 834 /**
 835  * pmd_free_pte_page - Clear pmd entry and free pte page.
 836  * @pmd: Pointer to a PMD.
 837  * @addr: Virtual address associated with pmd.
 838  *
 839  * Context: The pmd range has been unmapped and TLB purged.
 840  * Return: 1 if clearing the entry succeeded. 0 otherwise.
 841  */
 842 int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 843 {
 844         pte_t *pte;
 845 
 846         pte = (pte_t *)pmd_page_vaddr(*pmd);
 847         pmd_clear(pmd);
 848 
 849         /* INVLPG to clear all paging-structure caches */
 850         flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
 851 
 852         free_page((unsigned long)pte);
 853 
 854         return 1;
 855 }
 856 
 857 #else /* !CONFIG_X86_64 */
 858 
 859 int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 860 {
 861         return pud_none(*pud);
 862 }
 863 
 864 /*
 865  * Disable free page handling on x86-PAE. This assures that ioremap()
 866  * does not update sync'd pmd entries. See vmalloc_sync_one().
 867  */
 868 int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 869 {
 870         return pmd_none(*pmd);
 871 }
 872 
 873 #endif /* CONFIG_X86_64 */
 874 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
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root/arch/x86/mm/pgtable.c

DEFINITIONS
