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Linux/arch/x86/mm/pgtable.c

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  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 */
875 

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