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Linux/arch/arm64/mm/mmu.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * Based on arch/arm/mm/mmu.c
  4  *
  5  * Copyright (C) 1995-2005 Russell King
  6  * Copyright (C) 2012 ARM Ltd.
  7  */
  8 
  9 #include <linux/cache.h>
 10 #include <linux/export.h>
 11 #include <linux/kernel.h>
 12 #include <linux/errno.h>
 13 #include <linux/init.h>
 14 #include <linux/ioport.h>
 15 #include <linux/kexec.h>
 16 #include <linux/libfdt.h>
 17 #include <linux/mman.h>
 18 #include <linux/nodemask.h>
 19 #include <linux/memblock.h>
 20 #include <linux/memory.h>
 21 #include <linux/fs.h>
 22 #include <linux/io.h>
 23 #include <linux/mm.h>
 24 #include <linux/vmalloc.h>
 25 #include <linux/set_memory.h>
 26 
 27 #include <asm/barrier.h>
 28 #include <asm/cputype.h>
 29 #include <asm/fixmap.h>
 30 #include <asm/kasan.h>
 31 #include <asm/kernel-pgtable.h>
 32 #include <asm/sections.h>
 33 #include <asm/setup.h>
 34 #include <linux/sizes.h>
 35 #include <asm/tlb.h>
 36 #include <asm/mmu_context.h>
 37 #include <asm/ptdump.h>
 38 #include <asm/tlbflush.h>
 39 #include <asm/pgalloc.h>
 40 
 41 #define NO_BLOCK_MAPPINGS       BIT(0)
 42 #define NO_CONT_MAPPINGS        BIT(1)
 43 #define NO_EXEC_MAPPINGS        BIT(2)  /* assumes FEAT_HPDS is not used */
 44 
 45 u64 idmap_t0sz = TCR_T0SZ(VA_BITS_MIN);
 46 u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
 47 
 48 u64 __section(".mmuoff.data.write") vabits_actual;
 49 EXPORT_SYMBOL(vabits_actual);
 50 
 51 u64 kimage_voffset __ro_after_init;
 52 EXPORT_SYMBOL(kimage_voffset);
 53 
 54 /*
 55  * Empty_zero_page is a special page that is used for zero-initialized data
 56  * and COW.
 57  */
 58 unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 59 EXPORT_SYMBOL(empty_zero_page);
 60 
 61 static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss;
 62 static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused;
 63 static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused;
 64 
 65 static DEFINE_SPINLOCK(swapper_pgdir_lock);
 66 
 67 void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
 68 {
 69         pgd_t *fixmap_pgdp;
 70 
 71         spin_lock(&swapper_pgdir_lock);
 72         fixmap_pgdp = pgd_set_fixmap(__pa_symbol(pgdp));
 73         WRITE_ONCE(*fixmap_pgdp, pgd);
 74         /*
 75          * We need dsb(ishst) here to ensure the page-table-walker sees
 76          * our new entry before set_p?d() returns. The fixmap's
 77          * flush_tlb_kernel_range() via clear_fixmap() does this for us.
 78          */
 79         pgd_clear_fixmap();
 80         spin_unlock(&swapper_pgdir_lock);
 81 }
 82 
 83 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 84                               unsigned long size, pgprot_t vma_prot)
 85 {
 86         if (!pfn_is_map_memory(pfn))
 87                 return pgprot_noncached(vma_prot);
 88         else if (file->f_flags & O_SYNC)
 89                 return pgprot_writecombine(vma_prot);
 90         return vma_prot;
 91 }
 92 EXPORT_SYMBOL(phys_mem_access_prot);
 93 
 94 static phys_addr_t __init early_pgtable_alloc(int shift)
 95 {
 96         phys_addr_t phys;
 97         void *ptr;
 98 
 99         phys = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
100         if (!phys)
101                 panic("Failed to allocate page table page\n");
102 
103         /*
104          * The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE
105          * slot will be free, so we can (ab)use the FIX_PTE slot to initialise
106          * any level of table.
107          */
108         ptr = pte_set_fixmap(phys);
109 
110         memset(ptr, 0, PAGE_SIZE);
111 
112         /*
113          * Implicit barriers also ensure the zeroed page is visible to the page
114          * table walker
115          */
116         pte_clear_fixmap();
117 
118         return phys;
119 }
120 
121 static bool pgattr_change_is_safe(u64 old, u64 new)
122 {
123         /*
124          * The following mapping attributes may be updated in live
125          * kernel mappings without the need for break-before-make.
126          */
127         pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG;
128 
129         /* creating or taking down mappings is always safe */
130         if (old == 0 || new == 0)
131                 return true;
132 
133         /* live contiguous mappings may not be manipulated at all */
134         if ((old | new) & PTE_CONT)
135                 return false;
136 
137         /* Transitioning from Non-Global to Global is unsafe */
138         if (old & ~new & PTE_NG)
139                 return false;
140 
141         /*
142          * Changing the memory type between Normal and Normal-Tagged is safe
143          * since Tagged is considered a permission attribute from the
144          * mismatched attribute aliases perspective.
145          */
146         if (((old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) ||
147              (old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)) &&
148             ((new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) ||
149              (new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)))
150                 mask |= PTE_ATTRINDX_MASK;
151 
152         return ((old ^ new) & ~mask) == 0;
153 }
154 
155 static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
156                      phys_addr_t phys, pgprot_t prot)
157 {
158         pte_t *ptep;
159 
160         ptep = pte_set_fixmap_offset(pmdp, addr);
161         do {
162                 pte_t old_pte = READ_ONCE(*ptep);
163 
164                 set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot));
165 
166                 /*
167                  * After the PTE entry has been populated once, we
168                  * only allow updates to the permission attributes.
169                  */
170                 BUG_ON(!pgattr_change_is_safe(pte_val(old_pte),
171                                               READ_ONCE(pte_val(*ptep))));
172 
173                 phys += PAGE_SIZE;
174         } while (ptep++, addr += PAGE_SIZE, addr != end);
175 
176         pte_clear_fixmap();
177 }
178 
179 static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
180                                 unsigned long end, phys_addr_t phys,
181                                 pgprot_t prot,
182                                 phys_addr_t (*pgtable_alloc)(int),
183                                 int flags)
184 {
185         unsigned long next;
186         pmd_t pmd = READ_ONCE(*pmdp);
187 
188         BUG_ON(pmd_sect(pmd));
189         if (pmd_none(pmd)) {
190                 pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN;
191                 phys_addr_t pte_phys;
192 
193                 if (flags & NO_EXEC_MAPPINGS)
194                         pmdval |= PMD_TABLE_PXN;
195                 BUG_ON(!pgtable_alloc);
196                 pte_phys = pgtable_alloc(PAGE_SHIFT);
197                 __pmd_populate(pmdp, pte_phys, pmdval);
198                 pmd = READ_ONCE(*pmdp);
199         }
200         BUG_ON(pmd_bad(pmd));
201 
202         do {
203                 pgprot_t __prot = prot;
204 
205                 next = pte_cont_addr_end(addr, end);
206 
207                 /* use a contiguous mapping if the range is suitably aligned */
208                 if ((((addr | next | phys) & ~CONT_PTE_MASK) == 0) &&
209                     (flags & NO_CONT_MAPPINGS) == 0)
210                         __prot = __pgprot(pgprot_val(prot) | PTE_CONT);
211 
212                 init_pte(pmdp, addr, next, phys, __prot);
213 
214                 phys += next - addr;
215         } while (addr = next, addr != end);
216 }
217 
218 static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end,
219                      phys_addr_t phys, pgprot_t prot,
220                      phys_addr_t (*pgtable_alloc)(int), int flags)
221 {
222         unsigned long next;
223         pmd_t *pmdp;
224 
225         pmdp = pmd_set_fixmap_offset(pudp, addr);
226         do {
227                 pmd_t old_pmd = READ_ONCE(*pmdp);
228 
229                 next = pmd_addr_end(addr, end);
230 
231                 /* try section mapping first */
232                 if (((addr | next | phys) & ~PMD_MASK) == 0 &&
233                     (flags & NO_BLOCK_MAPPINGS) == 0) {
234                         pmd_set_huge(pmdp, phys, prot);
235 
236                         /*
237                          * After the PMD entry has been populated once, we
238                          * only allow updates to the permission attributes.
239                          */
240                         BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd),
241                                                       READ_ONCE(pmd_val(*pmdp))));
242                 } else {
243                         alloc_init_cont_pte(pmdp, addr, next, phys, prot,
244                                             pgtable_alloc, flags);
245 
246                         BUG_ON(pmd_val(old_pmd) != 0 &&
247                                pmd_val(old_pmd) != READ_ONCE(pmd_val(*pmdp)));
248                 }
249                 phys += next - addr;
250         } while (pmdp++, addr = next, addr != end);
251 
252         pmd_clear_fixmap();
253 }
254 
255 static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
256                                 unsigned long end, phys_addr_t phys,
257                                 pgprot_t prot,
258                                 phys_addr_t (*pgtable_alloc)(int), int flags)
259 {
260         unsigned long next;
261         pud_t pud = READ_ONCE(*pudp);
262 
263         /*
264          * Check for initial section mappings in the pgd/pud.
265          */
266         BUG_ON(pud_sect(pud));
267         if (pud_none(pud)) {
268                 pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN;
269                 phys_addr_t pmd_phys;
270 
271                 if (flags & NO_EXEC_MAPPINGS)
272                         pudval |= PUD_TABLE_PXN;
273                 BUG_ON(!pgtable_alloc);
274                 pmd_phys = pgtable_alloc(PMD_SHIFT);
275                 __pud_populate(pudp, pmd_phys, pudval);
276                 pud = READ_ONCE(*pudp);
277         }
278         BUG_ON(pud_bad(pud));
279 
280         do {
281                 pgprot_t __prot = prot;
282 
283                 next = pmd_cont_addr_end(addr, end);
284 
285                 /* use a contiguous mapping if the range is suitably aligned */
286                 if ((((addr | next | phys) & ~CONT_PMD_MASK) == 0) &&
287                     (flags & NO_CONT_MAPPINGS) == 0)
288                         __prot = __pgprot(pgprot_val(prot) | PTE_CONT);
289 
290                 init_pmd(pudp, addr, next, phys, __prot, pgtable_alloc, flags);
291 
292                 phys += next - addr;
293         } while (addr = next, addr != end);
294 }
295 
296 static inline bool use_1G_block(unsigned long addr, unsigned long next,
297                         unsigned long phys)
298 {
299         if (PAGE_SHIFT != 12)
300                 return false;
301 
302         if (((addr | next | phys) & ~PUD_MASK) != 0)
303                 return false;
304 
305         return true;
306 }
307 
308 static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
309                            phys_addr_t phys, pgprot_t prot,
310                            phys_addr_t (*pgtable_alloc)(int),
311                            int flags)
312 {
313         unsigned long next;
314         pud_t *pudp;
315         p4d_t *p4dp = p4d_offset(pgdp, addr);
316         p4d_t p4d = READ_ONCE(*p4dp);
317 
318         if (p4d_none(p4d)) {
319                 p4dval_t p4dval = P4D_TYPE_TABLE | P4D_TABLE_UXN;
320                 phys_addr_t pud_phys;
321 
322                 if (flags & NO_EXEC_MAPPINGS)
323                         p4dval |= P4D_TABLE_PXN;
324                 BUG_ON(!pgtable_alloc);
325                 pud_phys = pgtable_alloc(PUD_SHIFT);
326                 __p4d_populate(p4dp, pud_phys, p4dval);
327                 p4d = READ_ONCE(*p4dp);
328         }
329         BUG_ON(p4d_bad(p4d));
330 
331         pudp = pud_set_fixmap_offset(p4dp, addr);
332         do {
333                 pud_t old_pud = READ_ONCE(*pudp);
334 
335                 next = pud_addr_end(addr, end);
336 
337                 /*
338                  * For 4K granule only, attempt to put down a 1GB block
339                  */
340                 if (use_1G_block(addr, next, phys) &&
341                     (flags & NO_BLOCK_MAPPINGS) == 0) {
342                         pud_set_huge(pudp, phys, prot);
343 
344                         /*
345                          * After the PUD entry has been populated once, we
346                          * only allow updates to the permission attributes.
347                          */
348                         BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
349                                                       READ_ONCE(pud_val(*pudp))));
350                 } else {
351                         alloc_init_cont_pmd(pudp, addr, next, phys, prot,
352                                             pgtable_alloc, flags);
353 
354                         BUG_ON(pud_val(old_pud) != 0 &&
355                                pud_val(old_pud) != READ_ONCE(pud_val(*pudp)));
356                 }
357                 phys += next - addr;
358         } while (pudp++, addr = next, addr != end);
359 
360         pud_clear_fixmap();
361 }
362 
363 static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
364                                  unsigned long virt, phys_addr_t size,
365                                  pgprot_t prot,
366                                  phys_addr_t (*pgtable_alloc)(int),
367                                  int flags)
368 {
369         unsigned long addr, end, next;
370         pgd_t *pgdp = pgd_offset_pgd(pgdir, virt);
371 
372         /*
373          * If the virtual and physical address don't have the same offset
374          * within a page, we cannot map the region as the caller expects.
375          */
376         if (WARN_ON((phys ^ virt) & ~PAGE_MASK))
377                 return;
378 
379         phys &= PAGE_MASK;
380         addr = virt & PAGE_MASK;
381         end = PAGE_ALIGN(virt + size);
382 
383         do {
384                 next = pgd_addr_end(addr, end);
385                 alloc_init_pud(pgdp, addr, next, phys, prot, pgtable_alloc,
386                                flags);
387                 phys += next - addr;
388         } while (pgdp++, addr = next, addr != end);
389 }
390 
391 static phys_addr_t __pgd_pgtable_alloc(int shift)
392 {
393         void *ptr = (void *)__get_free_page(GFP_PGTABLE_KERNEL);
394         BUG_ON(!ptr);
395 
396         /* Ensure the zeroed page is visible to the page table walker */
397         dsb(ishst);
398         return __pa(ptr);
399 }
400 
401 static phys_addr_t pgd_pgtable_alloc(int shift)
402 {
403         phys_addr_t pa = __pgd_pgtable_alloc(shift);
404 
405         /*
406          * Call proper page table ctor in case later we need to
407          * call core mm functions like apply_to_page_range() on
408          * this pre-allocated page table.
409          *
410          * We don't select ARCH_ENABLE_SPLIT_PMD_PTLOCK if pmd is
411          * folded, and if so pgtable_pmd_page_ctor() becomes nop.
412          */
413         if (shift == PAGE_SHIFT)
414                 BUG_ON(!pgtable_pte_page_ctor(phys_to_page(pa)));
415         else if (shift == PMD_SHIFT)
416                 BUG_ON(!pgtable_pmd_page_ctor(phys_to_page(pa)));
417 
418         return pa;
419 }
420 
421 /*
422  * This function can only be used to modify existing table entries,
423  * without allocating new levels of table. Note that this permits the
424  * creation of new section or page entries.
425  */
426 static void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
427                                   phys_addr_t size, pgprot_t prot)
428 {
429         if ((virt >= PAGE_END) && (virt < VMALLOC_START)) {
430                 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n",
431                         &phys, virt);
432                 return;
433         }
434         __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL,
435                              NO_CONT_MAPPINGS);
436 }
437 
438 void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
439                                unsigned long virt, phys_addr_t size,
440                                pgprot_t prot, bool page_mappings_only)
441 {
442         int flags = 0;
443 
444         BUG_ON(mm == &init_mm);
445 
446         if (page_mappings_only)
447                 flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
448 
449         __create_pgd_mapping(mm->pgd, phys, virt, size, prot,
450                              pgd_pgtable_alloc, flags);
451 }
452 
453 static void update_mapping_prot(phys_addr_t phys, unsigned long virt,
454                                 phys_addr_t size, pgprot_t prot)
455 {
456         if ((virt >= PAGE_END) && (virt < VMALLOC_START)) {
457                 pr_warn("BUG: not updating mapping for %pa at 0x%016lx - outside kernel range\n",
458                         &phys, virt);
459                 return;
460         }
461 
462         __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL,
463                              NO_CONT_MAPPINGS);
464 
465         /* flush the TLBs after updating live kernel mappings */
466         flush_tlb_kernel_range(virt, virt + size);
467 }
468 
469 static void __init __map_memblock(pgd_t *pgdp, phys_addr_t start,
470                                   phys_addr_t end, pgprot_t prot, int flags)
471 {
472         __create_pgd_mapping(pgdp, start, __phys_to_virt(start), end - start,
473                              prot, early_pgtable_alloc, flags);
474 }
475 
476 void __init mark_linear_text_alias_ro(void)
477 {
478         /*
479          * Remove the write permissions from the linear alias of .text/.rodata
480          */
481         update_mapping_prot(__pa_symbol(_stext), (unsigned long)lm_alias(_stext),
482                             (unsigned long)__init_begin - (unsigned long)_stext,
483                             PAGE_KERNEL_RO);
484 }
485 
486 static bool crash_mem_map __initdata;
487 
488 static int __init enable_crash_mem_map(char *arg)
489 {
490         /*
491          * Proper parameter parsing is done by reserve_crashkernel(). We only
492          * need to know if the linear map has to avoid block mappings so that
493          * the crashkernel reservations can be unmapped later.
494          */
495         crash_mem_map = true;
496 
497         return 0;
498 }
499 early_param("crashkernel", enable_crash_mem_map);
500 
501 static void __init map_mem(pgd_t *pgdp)
502 {
503         static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN);
504         phys_addr_t kernel_start = __pa_symbol(_stext);
505         phys_addr_t kernel_end = __pa_symbol(__init_begin);
506         phys_addr_t start, end;
507         int flags = NO_EXEC_MAPPINGS;
508         u64 i;
509 
510         /*
511          * Setting hierarchical PXNTable attributes on table entries covering
512          * the linear region is only possible if it is guaranteed that no table
513          * entries at any level are being shared between the linear region and
514          * the vmalloc region. Check whether this is true for the PGD level, in
515          * which case it is guaranteed to be true for all other levels as well.
516          */
517         BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end));
518 
519         if (can_set_direct_map() || crash_mem_map || IS_ENABLED(CONFIG_KFENCE))
520                 flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
521 
522         /*
523          * Take care not to create a writable alias for the
524          * read-only text and rodata sections of the kernel image.
525          * So temporarily mark them as NOMAP to skip mappings in
526          * the following for-loop
527          */
528         memblock_mark_nomap(kernel_start, kernel_end - kernel_start);
529 
530         /* map all the memory banks */
531         for_each_mem_range(i, &start, &end) {
532                 if (start >= end)
533                         break;
534                 /*
535                  * The linear map must allow allocation tags reading/writing
536                  * if MTE is present. Otherwise, it has the same attributes as
537                  * PAGE_KERNEL.
538                  */
539                 __map_memblock(pgdp, start, end, pgprot_tagged(PAGE_KERNEL),
540                                flags);
541         }
542 
543         /*
544          * Map the linear alias of the [_stext, __init_begin) interval
545          * as non-executable now, and remove the write permission in
546          * mark_linear_text_alias_ro() below (which will be called after
547          * alternative patching has completed). This makes the contents
548          * of the region accessible to subsystems such as hibernate,
549          * but protects it from inadvertent modification or execution.
550          * Note that contiguous mappings cannot be remapped in this way,
551          * so we should avoid them here.
552          */
553         __map_memblock(pgdp, kernel_start, kernel_end,
554                        PAGE_KERNEL, NO_CONT_MAPPINGS);
555         memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
556 }
557 
558 void mark_rodata_ro(void)
559 {
560         unsigned long section_size;
561 
562         /*
563          * mark .rodata as read only. Use __init_begin rather than __end_rodata
564          * to cover NOTES and EXCEPTION_TABLE.
565          */
566         section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
567         update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
568                             section_size, PAGE_KERNEL_RO);
569 
570         debug_checkwx();
571 }
572 
573 static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end,
574                                       pgprot_t prot, struct vm_struct *vma,
575                                       int flags, unsigned long vm_flags)
576 {
577         phys_addr_t pa_start = __pa_symbol(va_start);
578         unsigned long size = va_end - va_start;
579 
580         BUG_ON(!PAGE_ALIGNED(pa_start));
581         BUG_ON(!PAGE_ALIGNED(size));
582 
583         __create_pgd_mapping(pgdp, pa_start, (unsigned long)va_start, size, prot,
584                              early_pgtable_alloc, flags);
585 
586         if (!(vm_flags & VM_NO_GUARD))
587                 size += PAGE_SIZE;
588 
589         vma->addr       = va_start;
590         vma->phys_addr  = pa_start;
591         vma->size       = size;
592         vma->flags      = VM_MAP | vm_flags;
593         vma->caller     = __builtin_return_address(0);
594 
595         vm_area_add_early(vma);
596 }
597 
598 static int __init parse_rodata(char *arg)
599 {
600         int ret = strtobool(arg, &rodata_enabled);
601         if (!ret) {
602                 rodata_full = false;
603                 return 0;
604         }
605 
606         /* permit 'full' in addition to boolean options */
607         if (strcmp(arg, "full"))
608                 return -EINVAL;
609 
610         rodata_enabled = true;
611         rodata_full = true;
612         return 0;
613 }
614 early_param("rodata", parse_rodata);
615 
616 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
617 static int __init map_entry_trampoline(void)
618 {
619         pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
620         phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start);
621 
622         /* The trampoline is always mapped and can therefore be global */
623         pgprot_val(prot) &= ~PTE_NG;
624 
625         /* Map only the text into the trampoline page table */
626         memset(tramp_pg_dir, 0, PGD_SIZE);
627         __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE,
628                              prot, __pgd_pgtable_alloc, 0);
629 
630         /* Map both the text and data into the kernel page table */
631         __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);
632         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
633                 extern char __entry_tramp_data_start[];
634 
635                 __set_fixmap(FIX_ENTRY_TRAMP_DATA,
636                              __pa_symbol(__entry_tramp_data_start),
637                              PAGE_KERNEL_RO);
638         }
639 
640         return 0;
641 }
642 core_initcall(map_entry_trampoline);
643 #endif
644 
645 /*
646  * Open coded check for BTI, only for use to determine configuration
647  * for early mappings for before the cpufeature code has run.
648  */
649 static bool arm64_early_this_cpu_has_bti(void)
650 {
651         u64 pfr1;
652 
653         if (!IS_ENABLED(CONFIG_ARM64_BTI_KERNEL))
654                 return false;
655 
656         pfr1 = __read_sysreg_by_encoding(SYS_ID_AA64PFR1_EL1);
657         return cpuid_feature_extract_unsigned_field(pfr1,
658                                                     ID_AA64PFR1_BT_SHIFT);
659 }
660 
661 /*
662  * Create fine-grained mappings for the kernel.
663  */
664 static void __init map_kernel(pgd_t *pgdp)
665 {
666         static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_inittext,
667                                 vmlinux_initdata, vmlinux_data;
668 
669         /*
670          * External debuggers may need to write directly to the text
671          * mapping to install SW breakpoints. Allow this (only) when
672          * explicitly requested with rodata=off.
673          */
674         pgprot_t text_prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
675 
676         /*
677          * If we have a CPU that supports BTI and a kernel built for
678          * BTI then mark the kernel executable text as guarded pages
679          * now so we don't have to rewrite the page tables later.
680          */
681         if (arm64_early_this_cpu_has_bti())
682                 text_prot = __pgprot_modify(text_prot, PTE_GP, PTE_GP);
683 
684         /*
685          * Only rodata will be remapped with different permissions later on,
686          * all other segments are allowed to use contiguous mappings.
687          */
688         map_kernel_segment(pgdp, _stext, _etext, text_prot, &vmlinux_text, 0,
689                            VM_NO_GUARD);
690         map_kernel_segment(pgdp, __start_rodata, __inittext_begin, PAGE_KERNEL,
691                            &vmlinux_rodata, NO_CONT_MAPPINGS, VM_NO_GUARD);
692         map_kernel_segment(pgdp, __inittext_begin, __inittext_end, text_prot,
693                            &vmlinux_inittext, 0, VM_NO_GUARD);
694         map_kernel_segment(pgdp, __initdata_begin, __initdata_end, PAGE_KERNEL,
695                            &vmlinux_initdata, 0, VM_NO_GUARD);
696         map_kernel_segment(pgdp, _data, _end, PAGE_KERNEL, &vmlinux_data, 0, 0);
697 
698         if (!READ_ONCE(pgd_val(*pgd_offset_pgd(pgdp, FIXADDR_START)))) {
699                 /*
700                  * The fixmap falls in a separate pgd to the kernel, and doesn't
701                  * live in the carveout for the swapper_pg_dir. We can simply
702                  * re-use the existing dir for the fixmap.
703                  */
704                 set_pgd(pgd_offset_pgd(pgdp, FIXADDR_START),
705                         READ_ONCE(*pgd_offset_k(FIXADDR_START)));
706         } else if (CONFIG_PGTABLE_LEVELS > 3) {
707                 pgd_t *bm_pgdp;
708                 p4d_t *bm_p4dp;
709                 pud_t *bm_pudp;
710                 /*
711                  * The fixmap shares its top level pgd entry with the kernel
712                  * mapping. This can really only occur when we are running
713                  * with 16k/4 levels, so we can simply reuse the pud level
714                  * entry instead.
715                  */
716                 BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
717                 bm_pgdp = pgd_offset_pgd(pgdp, FIXADDR_START);
718                 bm_p4dp = p4d_offset(bm_pgdp, FIXADDR_START);
719                 bm_pudp = pud_set_fixmap_offset(bm_p4dp, FIXADDR_START);
720                 pud_populate(&init_mm, bm_pudp, lm_alias(bm_pmd));
721                 pud_clear_fixmap();
722         } else {
723                 BUG();
724         }
725 
726         kasan_copy_shadow(pgdp);
727 }
728 
729 void __init paging_init(void)
730 {
731         pgd_t *pgdp = pgd_set_fixmap(__pa_symbol(swapper_pg_dir));
732 
733         map_kernel(pgdp);
734         map_mem(pgdp);
735 
736         pgd_clear_fixmap();
737 
738         cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
739         init_mm.pgd = swapper_pg_dir;
740 
741         memblock_free(__pa_symbol(init_pg_dir),
742                       __pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir));
743 
744         memblock_allow_resize();
745 }
746 
747 /*
748  * Check whether a kernel address is valid (derived from arch/x86/).
749  */
750 int kern_addr_valid(unsigned long addr)
751 {
752         pgd_t *pgdp;
753         p4d_t *p4dp;
754         pud_t *pudp, pud;
755         pmd_t *pmdp, pmd;
756         pte_t *ptep, pte;
757 
758         addr = arch_kasan_reset_tag(addr);
759         if ((((long)addr) >> VA_BITS) != -1UL)
760                 return 0;
761 
762         pgdp = pgd_offset_k(addr);
763         if (pgd_none(READ_ONCE(*pgdp)))
764                 return 0;
765 
766         p4dp = p4d_offset(pgdp, addr);
767         if (p4d_none(READ_ONCE(*p4dp)))
768                 return 0;
769 
770         pudp = pud_offset(p4dp, addr);
771         pud = READ_ONCE(*pudp);
772         if (pud_none(pud))
773                 return 0;
774 
775         if (pud_sect(pud))
776                 return pfn_valid(pud_pfn(pud));
777 
778         pmdp = pmd_offset(pudp, addr);
779         pmd = READ_ONCE(*pmdp);
780         if (pmd_none(pmd))
781                 return 0;
782 
783         if (pmd_sect(pmd))
784                 return pfn_valid(pmd_pfn(pmd));
785 
786         ptep = pte_offset_kernel(pmdp, addr);
787         pte = READ_ONCE(*ptep);
788         if (pte_none(pte))
789                 return 0;
790 
791         return pfn_valid(pte_pfn(pte));
792 }
793 
794 #ifdef CONFIG_MEMORY_HOTPLUG
795 static void free_hotplug_page_range(struct page *page, size_t size,
796                                     struct vmem_altmap *altmap)
797 {
798         if (altmap) {
799                 vmem_altmap_free(altmap, size >> PAGE_SHIFT);
800         } else {
801                 WARN_ON(PageReserved(page));
802                 free_pages((unsigned long)page_address(page), get_order(size));
803         }
804 }
805 
806 static void free_hotplug_pgtable_page(struct page *page)
807 {
808         free_hotplug_page_range(page, PAGE_SIZE, NULL);
809 }
810 
811 static bool pgtable_range_aligned(unsigned long start, unsigned long end,
812                                   unsigned long floor, unsigned long ceiling,
813                                   unsigned long mask)
814 {
815         start &= mask;
816         if (start < floor)
817                 return false;
818 
819         if (ceiling) {
820                 ceiling &= mask;
821                 if (!ceiling)
822                         return false;
823         }
824 
825         if (end - 1 > ceiling - 1)
826                 return false;
827         return true;
828 }
829 
830 static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr,
831                                     unsigned long end, bool free_mapped,
832                                     struct vmem_altmap *altmap)
833 {
834         pte_t *ptep, pte;
835 
836         do {
837                 ptep = pte_offset_kernel(pmdp, addr);
838                 pte = READ_ONCE(*ptep);
839                 if (pte_none(pte))
840                         continue;
841 
842                 WARN_ON(!pte_present(pte));
843                 pte_clear(&init_mm, addr, ptep);
844                 flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
845                 if (free_mapped)
846                         free_hotplug_page_range(pte_page(pte),
847                                                 PAGE_SIZE, altmap);
848         } while (addr += PAGE_SIZE, addr < end);
849 }
850 
851 static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr,
852                                     unsigned long end, bool free_mapped,
853                                     struct vmem_altmap *altmap)
854 {
855         unsigned long next;
856         pmd_t *pmdp, pmd;
857 
858         do {
859                 next = pmd_addr_end(addr, end);
860                 pmdp = pmd_offset(pudp, addr);
861                 pmd = READ_ONCE(*pmdp);
862                 if (pmd_none(pmd))
863                         continue;
864 
865                 WARN_ON(!pmd_present(pmd));
866                 if (pmd_sect(pmd)) {
867                         pmd_clear(pmdp);
868 
869                         /*
870                          * One TLBI should be sufficient here as the PMD_SIZE
871                          * range is mapped with a single block entry.
872                          */
873                         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
874                         if (free_mapped)
875                                 free_hotplug_page_range(pmd_page(pmd),
876                                                         PMD_SIZE, altmap);
877                         continue;
878                 }
879                 WARN_ON(!pmd_table(pmd));
880                 unmap_hotplug_pte_range(pmdp, addr, next, free_mapped, altmap);
881         } while (addr = next, addr < end);
882 }
883 
884 static void unmap_hotplug_pud_range(p4d_t *p4dp, unsigned long addr,
885                                     unsigned long end, bool free_mapped,
886                                     struct vmem_altmap *altmap)
887 {
888         unsigned long next;
889         pud_t *pudp, pud;
890 
891         do {
892                 next = pud_addr_end(addr, end);
893                 pudp = pud_offset(p4dp, addr);
894                 pud = READ_ONCE(*pudp);
895                 if (pud_none(pud))
896                         continue;
897 
898                 WARN_ON(!pud_present(pud));
899                 if (pud_sect(pud)) {
900                         pud_clear(pudp);
901 
902                         /*
903                          * One TLBI should be sufficient here as the PUD_SIZE
904                          * range is mapped with a single block entry.
905                          */
906                         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
907                         if (free_mapped)
908                                 free_hotplug_page_range(pud_page(pud),
909                                                         PUD_SIZE, altmap);
910                         continue;
911                 }
912                 WARN_ON(!pud_table(pud));
913                 unmap_hotplug_pmd_range(pudp, addr, next, free_mapped, altmap);
914         } while (addr = next, addr < end);
915 }
916 
917 static void unmap_hotplug_p4d_range(pgd_t *pgdp, unsigned long addr,
918                                     unsigned long end, bool free_mapped,
919                                     struct vmem_altmap *altmap)
920 {
921         unsigned long next;
922         p4d_t *p4dp, p4d;
923 
924         do {
925                 next = p4d_addr_end(addr, end);
926                 p4dp = p4d_offset(pgdp, addr);
927                 p4d = READ_ONCE(*p4dp);
928                 if (p4d_none(p4d))
929                         continue;
930 
931                 WARN_ON(!p4d_present(p4d));
932                 unmap_hotplug_pud_range(p4dp, addr, next, free_mapped, altmap);
933         } while (addr = next, addr < end);
934 }
935 
936 static void unmap_hotplug_range(unsigned long addr, unsigned long end,
937                                 bool free_mapped, struct vmem_altmap *altmap)
938 {
939         unsigned long next;
940         pgd_t *pgdp, pgd;
941 
942         /*
943          * altmap can only be used as vmemmap mapping backing memory.
944          * In case the backing memory itself is not being freed, then
945          * altmap is irrelevant. Warn about this inconsistency when
946          * encountered.
947          */
948         WARN_ON(!free_mapped && altmap);
949 
950         do {
951                 next = pgd_addr_end(addr, end);
952                 pgdp = pgd_offset_k(addr);
953                 pgd = READ_ONCE(*pgdp);
954                 if (pgd_none(pgd))
955                         continue;
956 
957                 WARN_ON(!pgd_present(pgd));
958                 unmap_hotplug_p4d_range(pgdp, addr, next, free_mapped, altmap);
959         } while (addr = next, addr < end);
960 }
961 
962 static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr,
963                                  unsigned long end, unsigned long floor,
964                                  unsigned long ceiling)
965 {
966         pte_t *ptep, pte;
967         unsigned long i, start = addr;
968 
969         do {
970                 ptep = pte_offset_kernel(pmdp, addr);
971                 pte = READ_ONCE(*ptep);
972 
973                 /*
974                  * This is just a sanity check here which verifies that
975                  * pte clearing has been done by earlier unmap loops.
976                  */
977                 WARN_ON(!pte_none(pte));
978         } while (addr += PAGE_SIZE, addr < end);
979 
980         if (!pgtable_range_aligned(start, end, floor, ceiling, PMD_MASK))
981                 return;
982 
983         /*
984          * Check whether we can free the pte page if the rest of the
985          * entries are empty. Overlap with other regions have been
986          * handled by the floor/ceiling check.
987          */
988         ptep = pte_offset_kernel(pmdp, 0UL);
989         for (i = 0; i < PTRS_PER_PTE; i++) {
990                 if (!pte_none(READ_ONCE(ptep[i])))
991                         return;
992         }
993 
994         pmd_clear(pmdp);
995         __flush_tlb_kernel_pgtable(start);
996         free_hotplug_pgtable_page(virt_to_page(ptep));
997 }
998 
999 static void free_empty_pmd_table(pud_t *pudp, unsigned long addr,
1000                                  unsigned long end, unsigned long floor,
1001                                  unsigned long ceiling)
1002 {
1003         pmd_t *pmdp, pmd;
1004         unsigned long i, next, start = addr;
1005 
1006         do {
1007                 next = pmd_addr_end(addr, end);
1008                 pmdp = pmd_offset(pudp, addr);
1009                 pmd = READ_ONCE(*pmdp);
1010                 if (pmd_none(pmd))
1011                         continue;
1012 
1013                 WARN_ON(!pmd_present(pmd) || !pmd_table(pmd) || pmd_sect(pmd));
1014                 free_empty_pte_table(pmdp, addr, next, floor, ceiling);
1015         } while (addr = next, addr < end);
1016 
1017         if (CONFIG_PGTABLE_LEVELS <= 2)
1018                 return;
1019 
1020         if (!pgtable_range_aligned(start, end, floor, ceiling, PUD_MASK))
1021                 return;
1022 
1023         /*
1024          * Check whether we can free the pmd page if the rest of the
1025          * entries are empty. Overlap with other regions have been
1026          * handled by the floor/ceiling check.
1027          */
1028         pmdp = pmd_offset(pudp, 0UL);
1029         for (i = 0; i < PTRS_PER_PMD; i++) {
1030                 if (!pmd_none(READ_ONCE(pmdp[i])))
1031                         return;
1032         }
1033 
1034         pud_clear(pudp);
1035         __flush_tlb_kernel_pgtable(start);
1036         free_hotplug_pgtable_page(virt_to_page(pmdp));
1037 }
1038 
1039 static void free_empty_pud_table(p4d_t *p4dp, unsigned long addr,
1040                                  unsigned long end, unsigned long floor,
1041                                  unsigned long ceiling)
1042 {
1043         pud_t *pudp, pud;
1044         unsigned long i, next, start = addr;
1045 
1046         do {
1047                 next = pud_addr_end(addr, end);
1048                 pudp = pud_offset(p4dp, addr);
1049                 pud = READ_ONCE(*pudp);
1050                 if (pud_none(pud))
1051                         continue;
1052 
1053                 WARN_ON(!pud_present(pud) || !pud_table(pud) || pud_sect(pud));
1054                 free_empty_pmd_table(pudp, addr, next, floor, ceiling);
1055         } while (addr = next, addr < end);
1056 
1057         if (CONFIG_PGTABLE_LEVELS <= 3)
1058                 return;
1059 
1060         if (!pgtable_range_aligned(start, end, floor, ceiling, PGDIR_MASK))
1061                 return;
1062 
1063         /*
1064          * Check whether we can free the pud page if the rest of the
1065          * entries are empty. Overlap with other regions have been
1066          * handled by the floor/ceiling check.
1067          */
1068         pudp = pud_offset(p4dp, 0UL);
1069         for (i = 0; i < PTRS_PER_PUD; i++) {
1070                 if (!pud_none(READ_ONCE(pudp[i])))
1071                         return;
1072         }
1073 
1074         p4d_clear(p4dp);
1075         __flush_tlb_kernel_pgtable(start);
1076         free_hotplug_pgtable_page(virt_to_page(pudp));
1077 }
1078 
1079 static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr,
1080                                  unsigned long end, unsigned long floor,
1081                                  unsigned long ceiling)
1082 {
1083         unsigned long next;
1084         p4d_t *p4dp, p4d;
1085 
1086         do {
1087                 next = p4d_addr_end(addr, end);
1088                 p4dp = p4d_offset(pgdp, addr);
1089                 p4d = READ_ONCE(*p4dp);
1090                 if (p4d_none(p4d))
1091                         continue;
1092 
1093                 WARN_ON(!p4d_present(p4d));
1094                 free_empty_pud_table(p4dp, addr, next, floor, ceiling);
1095         } while (addr = next, addr < end);
1096 }
1097 
1098 static void free_empty_tables(unsigned long addr, unsigned long end,
1099                               unsigned long floor, unsigned long ceiling)
1100 {
1101         unsigned long next;
1102         pgd_t *pgdp, pgd;
1103 
1104         do {
1105                 next = pgd_addr_end(addr, end);
1106                 pgdp = pgd_offset_k(addr);
1107                 pgd = READ_ONCE(*pgdp);
1108                 if (pgd_none(pgd))
1109                         continue;
1110 
1111                 WARN_ON(!pgd_present(pgd));
1112                 free_empty_p4d_table(pgdp, addr, next, floor, ceiling);
1113         } while (addr = next, addr < end);
1114 }
1115 #endif
1116 
1117 #if !ARM64_KERNEL_USES_PMD_MAPS
1118 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
1119                 struct vmem_altmap *altmap)
1120 {
1121         WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));
1122         return vmemmap_populate_basepages(start, end, node, altmap);
1123 }
1124 #else   /* !ARM64_KERNEL_USES_PMD_MAPS */
1125 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
1126                 struct vmem_altmap *altmap)
1127 {
1128         unsigned long addr = start;
1129         unsigned long next;
1130         pgd_t *pgdp;
1131         p4d_t *p4dp;
1132         pud_t *pudp;
1133         pmd_t *pmdp;
1134 
1135         WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));
1136         do {
1137                 next = pmd_addr_end(addr, end);
1138 
1139                 pgdp = vmemmap_pgd_populate(addr, node);
1140                 if (!pgdp)
1141                         return -ENOMEM;
1142 
1143                 p4dp = vmemmap_p4d_populate(pgdp, addr, node);
1144                 if (!p4dp)
1145                         return -ENOMEM;
1146 
1147                 pudp = vmemmap_pud_populate(p4dp, addr, node);
1148                 if (!pudp)
1149                         return -ENOMEM;
1150 
1151                 pmdp = pmd_offset(pudp, addr);
1152                 if (pmd_none(READ_ONCE(*pmdp))) {
1153                         void *p = NULL;
1154 
1155                         p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
1156                         if (!p) {
1157                                 if (vmemmap_populate_basepages(addr, next, node, altmap))
1158                                         return -ENOMEM;
1159                                 continue;
1160                         }
1161 
1162                         pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
1163                 } else
1164                         vmemmap_verify((pte_t *)pmdp, node, addr, next);
1165         } while (addr = next, addr != end);
1166 
1167         return 0;
1168 }
1169 #endif  /* !ARM64_KERNEL_USES_PMD_MAPS */
1170 
1171 #ifdef CONFIG_MEMORY_HOTPLUG
1172 void vmemmap_free(unsigned long start, unsigned long end,
1173                 struct vmem_altmap *altmap)
1174 {
1175         WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));
1176 
1177         unmap_hotplug_range(start, end, true, altmap);
1178         free_empty_tables(start, end, VMEMMAP_START, VMEMMAP_END);
1179 }
1180 #endif /* CONFIG_MEMORY_HOTPLUG */
1181 
1182 static inline pud_t *fixmap_pud(unsigned long addr)
1183 {
1184         pgd_t *pgdp = pgd_offset_k(addr);
1185         p4d_t *p4dp = p4d_offset(pgdp, addr);
1186         p4d_t p4d = READ_ONCE(*p4dp);
1187 
1188         BUG_ON(p4d_none(p4d) || p4d_bad(p4d));
1189 
1190         return pud_offset_kimg(p4dp, addr);
1191 }
1192 
1193 static inline pmd_t *fixmap_pmd(unsigned long addr)
1194 {
1195         pud_t *pudp = fixmap_pud(addr);
1196         pud_t pud = READ_ONCE(*pudp);
1197 
1198         BUG_ON(pud_none(pud) || pud_bad(pud));
1199 
1200         return pmd_offset_kimg(pudp, addr);
1201 }
1202 
1203 static inline pte_t *fixmap_pte(unsigned long addr)
1204 {
1205         return &bm_pte[pte_index(addr)];
1206 }
1207 
1208 /*
1209  * The p*d_populate functions call virt_to_phys implicitly so they can't be used
1210  * directly on kernel symbols (bm_p*d). This function is called too early to use
1211  * lm_alias so __p*d_populate functions must be used to populate with the
1212  * physical address from __pa_symbol.
1213  */
1214 void __init early_fixmap_init(void)
1215 {
1216         pgd_t *pgdp;
1217         p4d_t *p4dp, p4d;
1218         pud_t *pudp;
1219         pmd_t *pmdp;
1220         unsigned long addr = FIXADDR_START;
1221 
1222         pgdp = pgd_offset_k(addr);
1223         p4dp = p4d_offset(pgdp, addr);
1224         p4d = READ_ONCE(*p4dp);
1225         if (CONFIG_PGTABLE_LEVELS > 3 &&
1226             !(p4d_none(p4d) || p4d_page_paddr(p4d) == __pa_symbol(bm_pud))) {
1227                 /*
1228                  * We only end up here if the kernel mapping and the fixmap
1229                  * share the top level pgd entry, which should only happen on
1230                  * 16k/4 levels configurations.
1231                  */
1232                 BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
1233                 pudp = pud_offset_kimg(p4dp, addr);
1234         } else {
1235                 if (p4d_none(p4d))
1236                         __p4d_populate(p4dp, __pa_symbol(bm_pud), P4D_TYPE_TABLE);
1237                 pudp = fixmap_pud(addr);
1238         }
1239         if (pud_none(READ_ONCE(*pudp)))
1240                 __pud_populate(pudp, __pa_symbol(bm_pmd), PUD_TYPE_TABLE);
1241         pmdp = fixmap_pmd(addr);
1242         __pmd_populate(pmdp, __pa_symbol(bm_pte), PMD_TYPE_TABLE);
1243 
1244         /*
1245          * The boot-ioremap range spans multiple pmds, for which
1246          * we are not prepared:
1247          */
1248         BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
1249                      != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
1250 
1251         if ((pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)))
1252              || pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_END))) {
1253                 WARN_ON(1);
1254                 pr_warn("pmdp %p != %p, %p\n",
1255                         pmdp, fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)),
1256                         fixmap_pmd(fix_to_virt(FIX_BTMAP_END)));
1257                 pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
1258                         fix_to_virt(FIX_BTMAP_BEGIN));
1259                 pr_warn("fix_to_virt(FIX_BTMAP_END):   %08lx\n",
1260                         fix_to_virt(FIX_BTMAP_END));
1261 
1262                 pr_warn("FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
1263                 pr_warn("FIX_BTMAP_BEGIN:     %d\n", FIX_BTMAP_BEGIN);
1264         }
1265 }
1266 
1267 /*
1268  * Unusually, this is also called in IRQ context (ghes_iounmap_irq) so if we
1269  * ever need to use IPIs for TLB broadcasting, then we're in trouble here.
1270  */
1271 void __set_fixmap(enum fixed_addresses idx,
1272                                phys_addr_t phys, pgprot_t flags)
1273 {
1274         unsigned long addr = __fix_to_virt(idx);
1275         pte_t *ptep;
1276 
1277         BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);
1278 
1279         ptep = fixmap_pte(addr);
1280 
1281         if (pgprot_val(flags)) {
1282                 set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, flags));
1283         } else {
1284                 pte_clear(&init_mm, addr, ptep);
1285                 flush_tlb_kernel_range(addr, addr+PAGE_SIZE);
1286         }
1287 }
1288 
1289 void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
1290 {
1291         const u64 dt_virt_base = __fix_to_virt(FIX_FDT);
1292         int offset;
1293         void *dt_virt;
1294 
1295         /*
1296          * Check whether the physical FDT address is set and meets the minimum
1297          * alignment requirement. Since we are relying on MIN_FDT_ALIGN to be
1298          * at least 8 bytes so that we can always access the magic and size
1299          * fields of the FDT header after mapping the first chunk, double check
1300          * here if that is indeed the case.
1301          */
1302         BUILD_BUG_ON(MIN_FDT_ALIGN < 8);
1303         if (!dt_phys || dt_phys % MIN_FDT_ALIGN)
1304                 return NULL;
1305 
1306         /*
1307          * Make sure that the FDT region can be mapped without the need to
1308          * allocate additional translation table pages, so that it is safe
1309          * to call create_mapping_noalloc() this early.
1310          *
1311          * On 64k pages, the FDT will be mapped using PTEs, so we need to
1312          * be in the same PMD as the rest of the fixmap.
1313          * On 4k pages, we'll use section mappings for the FDT so we only
1314          * have to be in the same PUD.
1315          */
1316         BUILD_BUG_ON(dt_virt_base % SZ_2M);
1317 
1318         BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT !=
1319                      __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT);
1320 
1321         offset = dt_phys % SWAPPER_BLOCK_SIZE;
1322         dt_virt = (void *)dt_virt_base + offset;
1323 
1324         /* map the first chunk so we can read the size from the header */
1325         create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE),
1326                         dt_virt_base, SWAPPER_BLOCK_SIZE, prot);
1327 
1328         if (fdt_magic(dt_virt) != FDT_MAGIC)
1329                 return NULL;
1330 
1331         *size = fdt_totalsize(dt_virt);
1332         if (*size > MAX_FDT_SIZE)
1333                 return NULL;
1334 
1335         if (offset + *size > SWAPPER_BLOCK_SIZE)
1336                 create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base,
1337                                round_up(offset + *size, SWAPPER_BLOCK_SIZE), prot);
1338 
1339         return dt_virt;
1340 }
1341 
1342 int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
1343 {
1344         pud_t new_pud = pfn_pud(__phys_to_pfn(phys), mk_pud_sect_prot(prot));
1345 
1346         /* Only allow permission changes for now */
1347         if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)),
1348                                    pud_val(new_pud)))
1349                 return 0;
1350 
1351         VM_BUG_ON(phys & ~PUD_MASK);
1352         set_pud(pudp, new_pud);
1353         return 1;
1354 }
1355 
1356 int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
1357 {
1358         pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), mk_pmd_sect_prot(prot));
1359 
1360         /* Only allow permission changes for now */
1361         if (!pgattr_change_is_safe(READ_ONCE(pmd_val(*pmdp)),
1362                                    pmd_val(new_pmd)))
1363                 return 0;
1364 
1365         VM_BUG_ON(phys & ~PMD_MASK);
1366         set_pmd(pmdp, new_pmd);
1367         return 1;
1368 }
1369 
1370 int pud_clear_huge(pud_t *pudp)
1371 {
1372         if (!pud_sect(READ_ONCE(*pudp)))
1373                 return 0;
1374         pud_clear(pudp);
1375         return 1;
1376 }
1377 
1378 int pmd_clear_huge(pmd_t *pmdp)
1379 {
1380         if (!pmd_sect(READ_ONCE(*pmdp)))
1381                 return 0;
1382         pmd_clear(pmdp);
1383         return 1;
1384 }
1385 
1386 int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
1387 {
1388         pte_t *table;
1389         pmd_t pmd;
1390 
1391         pmd = READ_ONCE(*pmdp);
1392 
1393         if (!pmd_table(pmd)) {
1394                 VM_WARN_ON(1);
1395                 return 1;
1396         }
1397 
1398         table = pte_offset_kernel(pmdp, addr);
1399         pmd_clear(pmdp);
1400         __flush_tlb_kernel_pgtable(addr);
1401         pte_free_kernel(NULL, table);
1402         return 1;
1403 }
1404 
1405 int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
1406 {
1407         pmd_t *table;
1408         pmd_t *pmdp;
1409         pud_t pud;
1410         unsigned long next, end;
1411 
1412         pud = READ_ONCE(*pudp);
1413 
1414         if (!pud_table(pud)) {
1415                 VM_WARN_ON(1);
1416                 return 1;
1417         }
1418 
1419         table = pmd_offset(pudp, addr);
1420         pmdp = table;
1421         next = addr;
1422         end = addr + PUD_SIZE;
1423         do {
1424                 pmd_free_pte_page(pmdp, next);
1425         } while (pmdp++, next += PMD_SIZE, next != end);
1426 
1427         pud_clear(pudp);
1428         __flush_tlb_kernel_pgtable(addr);
1429         pmd_free(NULL, table);
1430         return 1;
1431 }
1432 
1433 #ifdef CONFIG_MEMORY_HOTPLUG
1434 static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size)
1435 {
1436         unsigned long end = start + size;
1437 
1438         WARN_ON(pgdir != init_mm.pgd);
1439         WARN_ON((start < PAGE_OFFSET) || (end > PAGE_END));
1440 
1441         unmap_hotplug_range(start, end, false, NULL);
1442         free_empty_tables(start, end, PAGE_OFFSET, PAGE_END);
1443 }
1444 
1445 struct range arch_get_mappable_range(void)
1446 {
1447         struct range mhp_range;
1448         u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual));
1449         u64 end_linear_pa = __pa(PAGE_END - 1);
1450 
1451         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
1452                 /*
1453                  * Check for a wrap, it is possible because of randomized linear
1454                  * mapping the start physical address is actually bigger than
1455                  * the end physical address. In this case set start to zero
1456                  * because [0, end_linear_pa] range must still be able to cover
1457                  * all addressable physical addresses.
1458                  */
1459                 if (start_linear_pa > end_linear_pa)
1460                         start_linear_pa = 0;
1461         }
1462 
1463         WARN_ON(start_linear_pa > end_linear_pa);
1464 
1465         /*
1466          * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)]
1467          * accommodating both its ends but excluding PAGE_END. Max physical
1468          * range which can be mapped inside this linear mapping range, must
1469          * also be derived from its end points.
1470          */
1471         mhp_range.start = start_linear_pa;
1472         mhp_range.end =  end_linear_pa;
1473 
1474         return mhp_range;
1475 }
1476 
1477 int arch_add_memory(int nid, u64 start, u64 size,
1478                     struct mhp_params *params)
1479 {
1480         int ret, flags = NO_EXEC_MAPPINGS;
1481 
1482         VM_BUG_ON(!mhp_range_allowed(start, size, true));
1483 
1484         /*
1485          * KFENCE requires linear map to be mapped at page granularity, so that
1486          * it is possible to protect/unprotect single pages in the KFENCE pool.
1487          */
1488         if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE))
1489                 flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
1490 
1491         __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
1492                              size, params->pgprot, __pgd_pgtable_alloc,
1493                              flags);
1494 
1495         memblock_clear_nomap(start, size);
1496 
1497         ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
1498                            params);
1499         if (ret)
1500                 __remove_pgd_mapping(swapper_pg_dir,
1501                                      __phys_to_virt(start), size);
1502         else {
1503                 max_pfn = PFN_UP(start + size);
1504                 max_low_pfn = max_pfn;
1505         }
1506 
1507         return ret;
1508 }
1509 
1510 void arch_remove_memory(int nid, u64 start, u64 size,
1511                         struct vmem_altmap *altmap)
1512 {
1513         unsigned long start_pfn = start >> PAGE_SHIFT;
1514         unsigned long nr_pages = size >> PAGE_SHIFT;
1515 
1516         __remove_pages(start_pfn, nr_pages, altmap);
1517         __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size);
1518 }
1519 
1520 /*
1521  * This memory hotplug notifier helps prevent boot memory from being
1522  * inadvertently removed as it blocks pfn range offlining process in
1523  * __offline_pages(). Hence this prevents both offlining as well as
1524  * removal process for boot memory which is initially always online.
1525  * In future if and when boot memory could be removed, this notifier
1526  * should be dropped and free_hotplug_page_range() should handle any
1527  * reserved pages allocated during boot.
1528  */
1529 static int prevent_bootmem_remove_notifier(struct notifier_block *nb,
1530                                            unsigned long action, void *data)
1531 {
1532         struct mem_section *ms;
1533         struct memory_notify *arg = data;
1534         unsigned long end_pfn = arg->start_pfn + arg->nr_pages;
1535         unsigned long pfn = arg->start_pfn;
1536 
1537         if ((action != MEM_GOING_OFFLINE) && (action != MEM_OFFLINE))
1538                 return NOTIFY_OK;
1539 
1540         for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1541                 unsigned long start = PFN_PHYS(pfn);
1542                 unsigned long end = start + (1UL << PA_SECTION_SHIFT);
1543 
1544                 ms = __pfn_to_section(pfn);
1545                 if (!early_section(ms))
1546                         continue;
1547 
1548                 if (action == MEM_GOING_OFFLINE) {
1549                         /*
1550                          * Boot memory removal is not supported. Prevent
1551                          * it via blocking any attempted offline request
1552                          * for the boot memory and just report it.
1553                          */
1554                         pr_warn("Boot memory [%lx %lx] offlining attempted\n", start, end);
1555                         return NOTIFY_BAD;
1556                 } else if (action == MEM_OFFLINE) {
1557                         /*
1558                          * This should have never happened. Boot memory
1559                          * offlining should have been prevented by this
1560                          * very notifier. Probably some memory removal
1561                          * procedure might have changed which would then
1562                          * require further debug.
1563                          */
1564                         pr_err("Boot memory [%lx %lx] offlined\n", start, end);
1565 
1566                         /*
1567                          * Core memory hotplug does not process a return
1568                          * code from the notifier for MEM_OFFLINE events.
1569                          * The error condition has been reported. Return
1570                          * from here as if ignored.
1571                          */
1572                         return NOTIFY_DONE;
1573                 }
1574         }
1575         return NOTIFY_OK;
1576 }
1577 
1578 static struct notifier_block prevent_bootmem_remove_nb = {
1579         .notifier_call = prevent_bootmem_remove_notifier,
1580 };
1581 
1582 /*
1583  * This ensures that boot memory sections on the platform are online
1584  * from early boot. Memory sections could not be prevented from being
1585  * offlined, unless for some reason they are not online to begin with.
1586  * This helps validate the basic assumption on which the above memory
1587  * event notifier works to prevent boot memory section offlining and
1588  * its possible removal.
1589  */
1590 static void validate_bootmem_online(void)
1591 {
1592         phys_addr_t start, end, addr;
1593         struct mem_section *ms;
1594         u64 i;
1595 
1596         /*
1597          * Scanning across all memblock might be expensive
1598          * on some big memory systems. Hence enable this
1599          * validation only with DEBUG_VM.
1600          */
1601         if (!IS_ENABLED(CONFIG_DEBUG_VM))
1602                 return;
1603 
1604         for_each_mem_range(i, &start, &end) {
1605                 for (addr = start; addr < end; addr += (1UL << PA_SECTION_SHIFT)) {
1606                         ms = __pfn_to_section(PHYS_PFN(addr));
1607 
1608                         /*
1609                          * All memory ranges in the system at this point
1610                          * should have been marked as early sections.
1611                          */
1612                         WARN_ON(!early_section(ms));
1613 
1614                         /*
1615                          * Memory notifier mechanism here to prevent boot
1616                          * memory offlining depends on the fact that each
1617                          * early section memory on the system is initially
1618                          * online. Otherwise a given memory section which
1619                          * is already offline will be overlooked and can
1620                          * be removed completely. Call out such sections.
1621                          */
1622                         if (!online_section(ms))
1623                                 pr_err("Boot memory [%llx %llx] is offline, can be removed\n",
1624                                         addr, addr + (1UL << PA_SECTION_SHIFT));
1625                 }
1626         }
1627 }
1628 
1629 static int __init prevent_bootmem_remove_init(void)
1630 {
1631         int ret = 0;
1632 
1633         if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
1634                 return ret;
1635 
1636         validate_bootmem_online();
1637         ret = register_memory_notifier(&prevent_bootmem_remove_nb);
1638         if (ret)
1639                 pr_err("%s: Notifier registration failed %d\n", __func__, ret);
1640 
1641         return ret;
1642 }
1643 early_initcall(prevent_bootmem_remove_init);
1644 #endif
1645 

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