개념 설명 전체 · v6.6 / arch/arm64/mm/mmu.c
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/memremap.h> 21 #include <linux/memory.h> 22 #include <linux/fs.h> 23 #include <linux/io.h> 24 #include <linux/mm.h> 25 #include <linux/vmalloc.h> 26 #include <linux/set_memory.h> 27 #include <linux/kfence.h> 28 29 #include <asm/barrier.h> 30 #include <asm/cputype.h> 31 #include <asm/fixmap.h> 32 #include <asm/kasan.h> 33 #include <asm/kernel-pgtable.h> 34 #include <asm/sections.h> 35 #include <asm/setup.h> 36 #include <linux/sizes.h> 37 #include <asm/tlb.h> 38 #include <asm/mmu_context.h> 39 #include <asm/ptdump.h> 40 #include <asm/tlbflush.h> 41 #include <asm/pgalloc.h> 42 #include <asm/kfence.h> 43 44 #define NO_BLOCK_MAPPINGS BIT(0) 45 #define NO_CONT_MAPPINGS BIT(1) 46 #define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */ 47 48 int idmap_t0sz __ro_after_init; 49 50 #if VA_BITS > 48 51 u64 vabits_actual __ro_after_init = VA_BITS_MIN; 52 EXPORT_SYMBOL(vabits_actual); 53 #endif 54 55 u64 kimage_vaddr __ro_after_init = (u64)&_text; 56 EXPORT_SYMBOL(kimage_vaddr); 57 58 u64 kimage_voffset __ro_after_init; 59 EXPORT_SYMBOL(kimage_voffset); 60 61 u32 __boot_cpu_mode[] = { BOOT_CPU_MODE_EL2, BOOT_CPU_MODE_EL1 }; 62 63 /* 64 * The booting CPU updates the failed status @__early_cpu_boot_status, 65 * with MMU turned off. 66 */ 67 long __section(".mmuoff.data.write") __early_cpu_boot_status; 68 69 /* 70 * Empty_zero_page is a special page that is used for zero-initialized data 71 * and COW. 72 */ 73 unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss; 74 EXPORT_SYMBOL(empty_zero_page); 75 76 static DEFINE_SPINLOCK(swapper_pgdir_lock); 77 static DEFINE_MUTEX(fixmap_lock); 78 79 void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd) 80 { 81 pgd_t *fixmap_pgdp; 82 83 spin_lock(&swapper_pgdir_lock); 84 fixmap_pgdp = pgd_set_fixmap(__pa_symbol(pgdp)); 85 WRITE_ONCE(*fixmap_pgdp, pgd); 86 /* 87 * We need dsb(ishst) here to ensure the page-table-walker sees 88 * our new entry before set_p?d() returns. The fixmap's 89 * flush_tlb_kernel_range() via clear_fixmap() does this for us. 90 */ 91 pgd_clear_fixmap(); 92 spin_unlock(&swapper_pgdir_lock); 93 } 94 95 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 96 unsigned long size, pgprot_t vma_prot) 97 { 98 if (!pfn_is_map_memory(pfn)) 99 return pgprot_noncached(vma_prot); 100 else if (file->f_flags & O_SYNC) 101 return pgprot_writecombine(vma_prot); 102 return vma_prot; 103 } 104 EXPORT_SYMBOL(phys_mem_access_prot); 105 106 static phys_addr_t __init early_pgtable_alloc(int shift) 107 { 108 phys_addr_t phys; 109 void *ptr; 110 111 phys = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0, 112 MEMBLOCK_ALLOC_NOLEAKTRACE); 113 if (!phys) 114 panic("Failed to allocate page table page\n"); 115 116 /* 117 * The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE 118 * slot will be free, so we can (ab)use the FIX_PTE slot to initialise 119 * any level of table. 120 */ 121 ptr = pte_set_fixmap(phys); 122 123 memset(ptr, 0, PAGE_SIZE); 124 125 /* 126 * Implicit barriers also ensure the zeroed page is visible to the page 127 * table walker 128 */ 129 pte_clear_fixmap(); 130 131 return phys; 132 } 133 134 bool pgattr_change_is_safe(u64 old, u64 new) 135 { 136 /* 137 * The following mapping attributes may be updated in live 138 * kernel mappings without the need for break-before-make. 139 */ 140 pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG; 141 142 /* creating or taking down mappings is always safe */ 143 if (!pte_valid(__pte(old)) || !pte_valid(__pte(new))) 144 return true; 145 146 /* A live entry's pfn should not change */ 147 if (pte_pfn(__pte(old)) != pte_pfn(__pte(new))) 148 return false; 149 150 /* live contiguous mappings may not be manipulated at all */ 151 if ((old | new) & PTE_CONT) 152 return false; 153 154 /* Transitioning from Non-Global to Global is unsafe */ 155 if (old & ~new & PTE_NG) 156 return false; 157 158 /* 159 * Changing the memory type between Normal and Normal-Tagged is safe 160 * since Tagged is considered a permission attribute from the 161 * mismatched attribute aliases perspective. 162 */ 163 if (((old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) || 164 (old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)) && 165 ((new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) || 166 (new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED))) 167 mask |= PTE_ATTRINDX_MASK; 168 169 return ((old ^ new) & ~mask) == 0; 170 } 171 172 static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end, 173 phys_addr_t phys, pgprot_t prot) 174 { 175 pte_t *ptep; 176 177 ptep = pte_set_fixmap_offset(pmdp, addr); 178 do { 179 pte_t old_pte = READ_ONCE(*ptep); 180 181 set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot)); 182 183 /* 184 * After the PTE entry has been populated once, we 185 * only allow updates to the permission attributes. 186 */ 187 BUG_ON(!pgattr_change_is_safe(pte_val(old_pte), 188 READ_ONCE(pte_val(*ptep)))); 189 190 phys += PAGE_SIZE; 191 } while (ptep++, addr += PAGE_SIZE, addr != end); 192 193 pte_clear_fixmap(); 194 } 195 196 static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr, 197 unsigned long end, phys_addr_t phys, 198 pgprot_t prot, 199 phys_addr_t (*pgtable_alloc)(int), 200 int flags) 201 { 202 unsigned long next; 203 pmd_t pmd = READ_ONCE(*pmdp); 204 205 BUG_ON(pmd_sect(pmd)); 206 if (pmd_none(pmd)) { 207 pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN; 208 phys_addr_t pte_phys; 209 210 if (flags & NO_EXEC_MAPPINGS) 211 pmdval |= PMD_TABLE_PXN; 212 BUG_ON(!pgtable_alloc); 213 pte_phys = pgtable_alloc(PAGE_SHIFT); 214 __pmd_populate(pmdp, pte_phys, pmdval); 215 pmd = READ_ONCE(*pmdp); 216 } 217 BUG_ON(pmd_bad(pmd)); 218 219 do { 220 pgprot_t __prot = prot; 221 222 next = pte_cont_addr_end(addr, end); 223 224 /* use a contiguous mapping if the range is suitably aligned */ 225 if ((((addr | next | phys) & ~CONT_PTE_MASK) == 0) && 226 (flags & NO_CONT_MAPPINGS) == 0) 227 __prot = __pgprot(pgprot_val(prot) | PTE_CONT); 228 229 init_pte(pmdp, addr, next, phys, __prot); 230 231 phys += next - addr; 232 } while (addr = next, addr != end); 233 } 234 235 static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end, 236 phys_addr_t phys, pgprot_t prot, 237 phys_addr_t (*pgtable_alloc)(int), int flags) 238 { 239 unsigned long next; 240 pmd_t *pmdp; 241 242 pmdp = pmd_set_fixmap_offset(pudp, addr); 243 do { 244 pmd_t old_pmd = READ_ONCE(*pmdp); 245 246 next = pmd_addr_end(addr, end); 247 248 /* try section mapping first */ 249 if (((addr | next | phys) & ~PMD_MASK) == 0 && 250 (flags & NO_BLOCK_MAPPINGS) == 0) { 251 pmd_set_huge(pmdp, phys, prot); 252 253 /* 254 * After the PMD entry has been populated once, we 255 * only allow updates to the permission attributes. 256 */ 257 BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd), 258 READ_ONCE(pmd_val(*pmdp)))); 259 } else { 260 alloc_init_cont_pte(pmdp, addr, next, phys, prot, 261 pgtable_alloc, flags); 262 263 BUG_ON(pmd_val(old_pmd) != 0 && 264 pmd_val(old_pmd) != READ_ONCE(pmd_val(*pmdp))); 265 } 266 phys += next - addr; 267 } while (pmdp++, addr = next, addr != end); 268 269 pmd_clear_fixmap(); 270 } 271 272 static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr, 273 unsigned long end, phys_addr_t phys, 274 pgprot_t prot, 275 phys_addr_t (*pgtable_alloc)(int), int flags) 276 { 277 unsigned long next; 278 pud_t pud = READ_ONCE(*pudp); 279 280 /* 281 * Check for initial section mappings in the pgd/pud. 282 */ 283 BUG_ON(pud_sect(pud)); 284 if (pud_none(pud)) { 285 pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN; 286 phys_addr_t pmd_phys; 287 288 if (flags & NO_EXEC_MAPPINGS) 289 pudval |= PUD_TABLE_PXN; 290 BUG_ON(!pgtable_alloc); 291 pmd_phys = pgtable_alloc(PMD_SHIFT); 292 __pud_populate(pudp, pmd_phys, pudval); 293 pud = READ_ONCE(*pudp); 294 } 295 BUG_ON(pud_bad(pud)); 296 297 do { 298 pgprot_t __prot = prot; 299 300 next = pmd_cont_addr_end(addr, end); 301 302 /* use a contiguous mapping if the range is suitably aligned */ 303 if ((((addr | next | phys) & ~CONT_PMD_MASK) == 0) && 304 (flags & NO_CONT_MAPPINGS) == 0) 305 __prot = __pgprot(pgprot_val(prot) | PTE_CONT); 306 307 init_pmd(pudp, addr, next, phys, __prot, pgtable_alloc, flags); 308 309 phys += next - addr; 310 } while (addr = next, addr != end); 311 } 312 313 static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end, 314 phys_addr_t phys, pgprot_t prot, 315 phys_addr_t (*pgtable_alloc)(int), 316 int flags) 317 { 318 unsigned long next; 319 pud_t *pudp; 320 p4d_t *p4dp = p4d_offset(pgdp, addr); 321 p4d_t p4d = READ_ONCE(*p4dp); 322 323 if (p4d_none(p4d)) { 324 p4dval_t p4dval = P4D_TYPE_TABLE | P4D_TABLE_UXN; 325 phys_addr_t pud_phys; 326 327 if (flags & NO_EXEC_MAPPINGS) 328 p4dval |= P4D_TABLE_PXN; 329 BUG_ON(!pgtable_alloc); 330 pud_phys = pgtable_alloc(PUD_SHIFT); 331 __p4d_populate(p4dp, pud_phys, p4dval); 332 p4d = READ_ONCE(*p4dp); 333 } 334 BUG_ON(p4d_bad(p4d)); 335 336 pudp = pud_set_fixmap_offset(p4dp, addr); 337 do { 338 pud_t old_pud = READ_ONCE(*pudp); 339 340 next = pud_addr_end(addr, end); 341 342 /* 343 * For 4K granule only, attempt to put down a 1GB block 344 */ 345 if (pud_sect_supported() && 346 ((addr | next | phys) & ~PUD_MASK) == 0 && 347 (flags & NO_BLOCK_MAPPINGS) == 0) { 348 pud_set_huge(pudp, phys, prot); 349 350 /* 351 * After the PUD entry has been populated once, we 352 * only allow updates to the permission attributes. 353 */ 354 BUG_ON(!pgattr_change_is_safe(pud_val(old_pud), 355 READ_ONCE(pud_val(*pudp)))); 356 } else { 357 alloc_init_cont_pmd(pudp, addr, next, phys, prot, 358 pgtable_alloc, flags); 359 360 BUG_ON(pud_val(old_pud) != 0 && 361 pud_val(old_pud) != READ_ONCE(pud_val(*pudp))); 362 } 363 phys += next - addr; 364 } while (pudp++, addr = next, addr != end); 365 366 pud_clear_fixmap(); 367 } 368 369 static void __create_pgd_mapping_locked(pgd_t *pgdir, phys_addr_t phys, 370 unsigned long virt, phys_addr_t size, 371 pgprot_t prot, 372 phys_addr_t (*pgtable_alloc)(int), 373 int flags) 374 { 375 unsigned long addr, end, next; 376 pgd_t *pgdp = pgd_offset_pgd(pgdir, virt); 377 378 /* 379 * If the virtual and physical address don't have the same offset 380 * within a page, we cannot map the region as the caller expects. 381 */ 382 if (WARN_ON((phys ^ virt) & ~PAGE_MASK)) 383 return; 384 385 phys &= PAGE_MASK; 386 addr = virt & PAGE_MASK; 387 end = PAGE_ALIGN(virt + size); 388 389 do { 390 next = pgd_addr_end(addr, end); 391 alloc_init_pud(pgdp, addr, next, phys, prot, pgtable_alloc, 392 flags); 393 phys += next - addr; 394 } while (pgdp++, addr = next, addr != end); 395 } 396 397 static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys, 398 unsigned long virt, phys_addr_t size, 399 pgprot_t prot, 400 phys_addr_t (*pgtable_alloc)(int), 401 int flags) 402 { 403 mutex_lock(&fixmap_lock); 404 __create_pgd_mapping_locked(pgdir, phys, virt, size, prot, 405 pgtable_alloc, flags); 406 mutex_unlock(&fixmap_lock); 407 } 408 409 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 410 extern __alias(__create_pgd_mapping_locked) 411 void create_kpti_ng_temp_pgd(pgd_t *pgdir, phys_addr_t phys, unsigned long virt, 412 phys_addr_t size, pgprot_t prot, 413 phys_addr_t (*pgtable_alloc)(int), int flags); 414 #endif 415 416 static phys_addr_t __pgd_pgtable_alloc(int shift) 417 { 418 void *ptr = (void *)__get_free_page(GFP_PGTABLE_KERNEL); 419 BUG_ON(!ptr); 420 421 /* Ensure the zeroed page is visible to the page table walker */ 422 dsb(ishst); 423 return __pa(ptr); 424 } 425 426 static phys_addr_t pgd_pgtable_alloc(int shift) 427 { 428 phys_addr_t pa = __pgd_pgtable_alloc(shift); 429 struct ptdesc *ptdesc = page_ptdesc(phys_to_page(pa)); 430 431 /* 432 * Call proper page table ctor in case later we need to 433 * call core mm functions like apply_to_page_range() on 434 * this pre-allocated page table. 435 * 436 * We don't select ARCH_ENABLE_SPLIT_PMD_PTLOCK if pmd is 437 * folded, and if so pagetable_pte_ctor() becomes nop. 438 */ 439 if (shift == PAGE_SHIFT) 440 BUG_ON(!pagetable_pte_ctor(ptdesc)); 441 else if (shift == PMD_SHIFT) 442 BUG_ON(!pagetable_pmd_ctor(ptdesc)); 443 444 return pa; 445 } 446 447 /* 448 * This function can only be used to modify existing table entries, 449 * without allocating new levels of table. Note that this permits the 450 * creation of new section or page entries. 451 */ 452 void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt, 453 phys_addr_t size, pgprot_t prot) 454 { 455 if (virt < PAGE_OFFSET) { 456 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", 457 &phys, virt); 458 return; 459 } 460 __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, 461 NO_CONT_MAPPINGS); 462 } 463 464 void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, 465 unsigned long virt, phys_addr_t size, 466 pgprot_t prot, bool page_mappings_only) 467 { 468 int flags = 0; 469 470 BUG_ON(mm == &init_mm); 471 472 if (page_mappings_only) 473 flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; 474 475 __create_pgd_mapping(mm->pgd, phys, virt, size, prot, 476 pgd_pgtable_alloc, flags); 477 } 478 479 static void update_mapping_prot(phys_addr_t phys, unsigned long virt, 480 phys_addr_t size, pgprot_t prot) 481 { 482 if (virt < PAGE_OFFSET) { 483 pr_warn("BUG: not updating mapping for %pa at 0x%016lx - outside kernel range\n", 484 &phys, virt); 485 return; 486 } 487 488 __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, 489 NO_CONT_MAPPINGS); 490 491 /* flush the TLBs after updating live kernel mappings */ 492 flush_tlb_kernel_range(virt, virt + size); 493 } 494 495 static void __init __map_memblock(pgd_t *pgdp, phys_addr_t start, 496 phys_addr_t end, pgprot_t prot, int flags) 497 { 498 __create_pgd_mapping(pgdp, start, __phys_to_virt(start), end - start, 499 prot, early_pgtable_alloc, flags); 500 } 501 502 void __init mark_linear_text_alias_ro(void) 503 { 504 /* 505 * Remove the write permissions from the linear alias of .text/.rodata 506 */ 507 update_mapping_prot(__pa_symbol(_stext), (unsigned long)lm_alias(_stext), 508 (unsigned long)__init_begin - (unsigned long)_stext, 509 PAGE_KERNEL_RO); 510 } 511 512 #ifdef CONFIG_KFENCE 513 514 bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL; 515 516 /* early_param() will be parsed before map_mem() below. */ 517 static int __init parse_kfence_early_init(char *arg) 518 { 519 int val; 520 521 if (get_option(&arg, &val)) 522 kfence_early_init = !!val; 523 return 0; 524 } 525 early_param("kfence.sample_interval", parse_kfence_early_init); 526 527 static phys_addr_t __init arm64_kfence_alloc_pool(void) 528 { 529 phys_addr_t kfence_pool; 530 531 if (!kfence_early_init) 532 return 0; 533 534 kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); 535 if (!kfence_pool) { 536 pr_err("failed to allocate kfence pool\n"); 537 kfence_early_init = false; 538 return 0; 539 } 540 541 /* Temporarily mark as NOMAP. */ 542 memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE); 543 544 return kfence_pool; 545 } 546 547 static void __init arm64_kfence_map_pool(phys_addr_t kfence_pool, pgd_t *pgdp) 548 { 549 if (!kfence_pool) 550 return; 551 552 /* KFENCE pool needs page-level mapping. */ 553 __map_memblock(pgdp, kfence_pool, kfence_pool + KFENCE_POOL_SIZE, 554 pgprot_tagged(PAGE_KERNEL), 555 NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); 556 memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE); 557 __kfence_pool = phys_to_virt(kfence_pool); 558 } 559 #else /* CONFIG_KFENCE */ 560 561 static inline phys_addr_t arm64_kfence_alloc_pool(void) { return 0; } 562 static inline void arm64_kfence_map_pool(phys_addr_t kfence_pool, pgd_t *pgdp) { } 563 564 #endif /* CONFIG_KFENCE */ 565 566 static void __init map_mem(pgd_t *pgdp) 567 { 568 static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN); 569 phys_addr_t kernel_start = __pa_symbol(_stext); 570 phys_addr_t kernel_end = __pa_symbol(__init_begin); 571 phys_addr_t start, end; 572 phys_addr_t early_kfence_pool; 573 int flags = NO_EXEC_MAPPINGS; 574 u64 i; 575 576 /* 577 * Setting hierarchical PXNTable attributes on table entries covering 578 * the linear region is only possible if it is guaranteed that no table 579 * entries at any level are being shared between the linear region and 580 * the vmalloc region. Check whether this is true for the PGD level, in 581 * which case it is guaranteed to be true for all other levels as well. 582 */ 583 BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end)); 584 585 early_kfence_pool = arm64_kfence_alloc_pool(); 586 587 if (can_set_direct_map()) 588 flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; 589 590 /* 591 * Take care not to create a writable alias for the 592 * read-only text and rodata sections of the kernel image. 593 * So temporarily mark them as NOMAP to skip mappings in 594 * the following for-loop 595 */ 596 memblock_mark_nomap(kernel_start, kernel_end - kernel_start); 597 598 /* map all the memory banks */ 599 for_each_mem_range(i, &start, &end) { 600 if (start >= end) 601 break; 602 /* 603 * The linear map must allow allocation tags reading/writing 604 * if MTE is present. Otherwise, it has the same attributes as 605 * PAGE_KERNEL. 606 */ 607 __map_memblock(pgdp, start, end, pgprot_tagged(PAGE_KERNEL), 608 flags); 609 } 610 611 /* 612 * Map the linear alias of the [_stext, __init_begin) interval 613 * as non-executable now, and remove the write permission in 614 * mark_linear_text_alias_ro() below (which will be called after 615 * alternative patching has completed). This makes the contents 616 * of the region accessible to subsystems such as hibernate, 617 * but protects it from inadvertent modification or execution. 618 * Note that contiguous mappings cannot be remapped in this way, 619 * so we should avoid them here. 620 */ 621 __map_memblock(pgdp, kernel_start, kernel_end, 622 PAGE_KERNEL, NO_CONT_MAPPINGS); 623 memblock_clear_nomap(kernel_start, kernel_end - kernel_start); 624 arm64_kfence_map_pool(early_kfence_pool, pgdp); 625 } 626 627 void mark_rodata_ro(void) 628 { 629 unsigned long section_size; 630 631 /* 632 * mark .rodata as read only. Use __init_begin rather than __end_rodata 633 * to cover NOTES and EXCEPTION_TABLE. 634 */ 635 section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata; 636 update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata, 637 section_size, PAGE_KERNEL_RO); 638 639 debug_checkwx(); 640 } 641 642 static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end, 643 pgprot_t prot, struct vm_struct *vma, 644 int flags, unsigned long vm_flags) 645 { 646 phys_addr_t pa_start = __pa_symbol(va_start); 647 unsigned long size = va_end - va_start; 648 649 BUG_ON(!PAGE_ALIGNED(pa_start)); 650 BUG_ON(!PAGE_ALIGNED(size)); 651 652 __create_pgd_mapping(pgdp, pa_start, (unsigned long)va_start, size, prot, 653 early_pgtable_alloc, flags); 654 655 if (!(vm_flags & VM_NO_GUARD)) 656 size += PAGE_SIZE; 657 658 vma->addr = va_start; 659 vma->phys_addr = pa_start; 660 vma->size = size; 661 vma->flags = VM_MAP | vm_flags; 662 vma->caller = __builtin_return_address(0); 663 664 vm_area_add_early(vma); 665 } 666 667 static pgprot_t kernel_exec_prot(void) 668 { 669 return rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; 670 } 671 672 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 673 static int __init map_entry_trampoline(void) 674 { 675 int i; 676 677 pgprot_t prot = kernel_exec_prot(); 678 phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start); 679 680 /* The trampoline is always mapped and can therefore be global */ 681 pgprot_val(prot) &= ~PTE_NG; 682 683 /* Map only the text into the trampoline page table */ 684 memset(tramp_pg_dir, 0, PGD_SIZE); 685 __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, 686 entry_tramp_text_size(), prot, 687 __pgd_pgtable_alloc, NO_BLOCK_MAPPINGS); 688 689 /* Map both the text and data into the kernel page table */ 690 for (i = 0; i < DIV_ROUND_UP(entry_tramp_text_size(), PAGE_SIZE); i++) 691 __set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i, 692 pa_start + i * PAGE_SIZE, prot); 693 694 if (IS_ENABLED(CONFIG_RELOCATABLE)) 695 __set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i, 696 pa_start + i * PAGE_SIZE, PAGE_KERNEL_RO); 697 698 return 0; 699 } 700 core_initcall(map_entry_trampoline); 701 #endif 702 703 /* 704 * Open coded check for BTI, only for use to determine configuration 705 * for early mappings for before the cpufeature code has run. 706 */ 707 static bool arm64_early_this_cpu_has_bti(void) 708 { 709 u64 pfr1; 710 711 if (!IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) 712 return false; 713 714 pfr1 = __read_sysreg_by_encoding(SYS_ID_AA64PFR1_EL1); 715 return cpuid_feature_extract_unsigned_field(pfr1, 716 ID_AA64PFR1_EL1_BT_SHIFT); 717 } 718 719 /* 720 * Create fine-grained mappings for the kernel. 721 */ 722 static void __init map_kernel(pgd_t *pgdp) 723 { 724 static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_inittext, 725 vmlinux_initdata, vmlinux_data; 726 727 /* 728 * External debuggers may need to write directly to the text 729 * mapping to install SW breakpoints. Allow this (only) when 730 * explicitly requested with rodata=off. 731 */ 732 pgprot_t text_prot = kernel_exec_prot(); 733 734 /* 735 * If we have a CPU that supports BTI and a kernel built for 736 * BTI then mark the kernel executable text as guarded pages 737 * now so we don't have to rewrite the page tables later. 738 */ 739 if (arm64_early_this_cpu_has_bti()) 740 text_prot = __pgprot_modify(text_prot, PTE_GP, PTE_GP); 741 742 /* 743 * Only rodata will be remapped with different permissions later on, 744 * all other segments are allowed to use contiguous mappings. 745 */ 746 map_kernel_segment(pgdp, _stext, _etext, text_prot, &vmlinux_text, 0, 747 VM_NO_GUARD); 748 map_kernel_segment(pgdp, __start_rodata, __inittext_begin, PAGE_KERNEL, 749 &vmlinux_rodata, NO_CONT_MAPPINGS, VM_NO_GUARD); 750 map_kernel_segment(pgdp, __inittext_begin, __inittext_end, text_prot, 751 &vmlinux_inittext, 0, VM_NO_GUARD); 752 map_kernel_segment(pgdp, __initdata_begin, __initdata_end, PAGE_KERNEL, 753 &vmlinux_initdata, 0, VM_NO_GUARD); 754 map_kernel_segment(pgdp, _data, _end, PAGE_KERNEL, &vmlinux_data, 0, 0); 755 756 fixmap_copy(pgdp); 757 kasan_copy_shadow(pgdp); 758 } 759 760 static void __init create_idmap(void) 761 { 762 u64 start = __pa_symbol(__idmap_text_start); 763 u64 size = __pa_symbol(__idmap_text_end) - start; 764 pgd_t *pgd = idmap_pg_dir; 765 u64 pgd_phys; 766 767 /* check if we need an additional level of translation */ 768 if (VA_BITS < 48 && idmap_t0sz < (64 - VA_BITS_MIN)) { 769 pgd_phys = early_pgtable_alloc(PAGE_SHIFT); 770 set_pgd(&idmap_pg_dir[start >> VA_BITS], 771 __pgd(pgd_phys | P4D_TYPE_TABLE)); 772 pgd = __va(pgd_phys); 773 } 774 __create_pgd_mapping(pgd, start, start, size, PAGE_KERNEL_ROX, 775 early_pgtable_alloc, 0); 776 777 if (IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) { 778 extern u32 __idmap_kpti_flag; 779 u64 pa = __pa_symbol(&__idmap_kpti_flag); 780 781 /* 782 * The KPTI G-to-nG conversion code needs a read-write mapping 783 * of its synchronization flag in the ID map. 784 */ 785 __create_pgd_mapping(pgd, pa, pa, sizeof(u32), PAGE_KERNEL, 786 early_pgtable_alloc, 0); 787 } 788 } 789 790 void __init paging_init(void) 791 { 792 pgd_t *pgdp = pgd_set_fixmap(__pa_symbol(swapper_pg_dir)); 793 extern pgd_t init_idmap_pg_dir[]; 794 795 idmap_t0sz = 63UL - __fls(__pa_symbol(_end) | GENMASK(VA_BITS_MIN - 1, 0)); 796 797 map_kernel(pgdp); 798 map_mem(pgdp); 799 800 pgd_clear_fixmap(); 801 802 cpu_replace_ttbr1(lm_alias(swapper_pg_dir), init_idmap_pg_dir); 803 init_mm.pgd = swapper_pg_dir; 804 805 memblock_phys_free(__pa_symbol(init_pg_dir), 806 __pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir)); 807 808 memblock_allow_resize(); 809 810 create_idmap(); 811 } 812 813 #ifdef CONFIG_MEMORY_HOTPLUG 814 static void free_hotplug_page_range(struct page *page, size_t size, 815 struct vmem_altmap *altmap) 816 { 817 if (altmap) { 818 vmem_altmap_free(altmap, size >> PAGE_SHIFT); 819 } else { 820 WARN_ON(PageReserved(page)); 821 free_pages((unsigned long)page_address(page), get_order(size)); 822 } 823 } 824 825 static void free_hotplug_pgtable_page(struct page *page) 826 { 827 free_hotplug_page_range(page, PAGE_SIZE, NULL); 828 } 829 830 static bool pgtable_range_aligned(unsigned long start, unsigned long end, 831 unsigned long floor, unsigned long ceiling, 832 unsigned long mask) 833 { 834 start &= mask; 835 if (start < floor) 836 return false; 837 838 if (ceiling) { 839 ceiling &= mask; 840 if (!ceiling) 841 return false; 842 } 843 844 if (end - 1 > ceiling - 1) 845 return false; 846 return true; 847 } 848 849 static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr, 850 unsigned long end, bool free_mapped, 851 struct vmem_altmap *altmap) 852 { 853 pte_t *ptep, pte; 854 855 do { 856 ptep = pte_offset_kernel(pmdp, addr); 857 pte = READ_ONCE(*ptep); 858 if (pte_none(pte)) 859 continue; 860 861 WARN_ON(!pte_present(pte)); 862 pte_clear(&init_mm, addr, ptep); 863 flush_tlb_kernel_range(addr, addr + PAGE_SIZE); 864 if (free_mapped) 865 free_hotplug_page_range(pte_page(pte), 866 PAGE_SIZE, altmap); 867 } while (addr += PAGE_SIZE, addr < end); 868 } 869 870 static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr, 871 unsigned long end, bool free_mapped, 872 struct vmem_altmap *altmap) 873 { 874 unsigned long next; 875 pmd_t *pmdp, pmd; 876 877 do { 878 next = pmd_addr_end(addr, end); 879 pmdp = pmd_offset(pudp, addr); 880 pmd = READ_ONCE(*pmdp); 881 if (pmd_none(pmd)) 882 continue; 883 884 WARN_ON(!pmd_present(pmd)); 885 if (pmd_sect(pmd)) { 886 pmd_clear(pmdp); 887 888 /* 889 * One TLBI should be sufficient here as the PMD_SIZE 890 * range is mapped with a single block entry. 891 */ 892 flush_tlb_kernel_range(addr, addr + PAGE_SIZE); 893 if (free_mapped) 894 free_hotplug_page_range(pmd_page(pmd), 895 PMD_SIZE, altmap); 896 continue; 897 } 898 WARN_ON(!pmd_table(pmd)); 899 unmap_hotplug_pte_range(pmdp, addr, next, free_mapped, altmap); 900 } while (addr = next, addr < end); 901 } 902 903 static void unmap_hotplug_pud_range(p4d_t *p4dp, unsigned long addr, 904 unsigned long end, bool free_mapped, 905 struct vmem_altmap *altmap) 906 { 907 unsigned long next; 908 pud_t *pudp, pud; 909 910 do { 911 next = pud_addr_end(addr, end); 912 pudp = pud_offset(p4dp, addr); 913 pud = READ_ONCE(*pudp); 914 if (pud_none(pud)) 915 continue; 916 917 WARN_ON(!pud_present(pud)); 918 if (pud_sect(pud)) { 919 pud_clear(pudp); 920 921 /* 922 * One TLBI should be sufficient here as the PUD_SIZE 923 * range is mapped with a single block entry. 924 */ 925 flush_tlb_kernel_range(addr, addr + PAGE_SIZE); 926 if (free_mapped) 927 free_hotplug_page_range(pud_page(pud), 928 PUD_SIZE, altmap); 929 continue; 930 } 931 WARN_ON(!pud_table(pud)); 932 unmap_hotplug_pmd_range(pudp, addr, next, free_mapped, altmap); 933 } while (addr = next, addr < end); 934 } 935 936 static void unmap_hotplug_p4d_range(pgd_t *pgdp, unsigned long addr, 937 unsigned long end, bool free_mapped, 938 struct vmem_altmap *altmap) 939 { 940 unsigned long next; 941 p4d_t *p4dp, p4d; 942 943 do { 944 next = p4d_addr_end(addr, end); 945 p4dp = p4d_offset(pgdp, addr); 946 p4d = READ_ONCE(*p4dp); 947 if (p4d_none(p4d)) 948 continue; 949 950 WARN_ON(!p4d_present(p4d)); 951 unmap_hotplug_pud_range(p4dp, addr, next, free_mapped, altmap); 952 } while (addr = next, addr < end); 953 } 954 955 static void unmap_hotplug_range(unsigned long addr, unsigned long end, 956 bool free_mapped, struct vmem_altmap *altmap) 957 { 958 unsigned long next; 959 pgd_t *pgdp, pgd; 960 961 /* 962 * altmap can only be used as vmemmap mapping backing memory. 963 * In case the backing memory itself is not being freed, then 964 * altmap is irrelevant. Warn about this inconsistency when 965 * encountered. 966 */ 967 WARN_ON(!free_mapped && altmap); 968 969 do { 970 next = pgd_addr_end(addr, end); 971 pgdp = pgd_offset_k(addr); 972 pgd = READ_ONCE(*pgdp); 973 if (pgd_none(pgd)) 974 continue; 975 976 WARN_ON(!pgd_present(pgd)); 977 unmap_hotplug_p4d_range(pgdp, addr, next, free_mapped, altmap); 978 } while (addr = next, addr < end); 979 } 980 981 static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr, 982 unsigned long end, unsigned long floor, 983 unsigned long ceiling) 984 { 985 pte_t *ptep, pte; 986 unsigned long i, start = addr; 987 988 do { 989 ptep = pte_offset_kernel(pmdp, addr); 990 pte = READ_ONCE(*ptep); 991 992 /* 993 * This is just a sanity check here which verifies that 994 * pte clearing has been done by earlier unmap loops. 995 */ 996 WARN_ON(!pte_none(pte)); 997 } while (addr += PAGE_SIZE, addr < end); 998 999 if (!pgtable_range_aligned(start, end, floor, ceiling, PMD_MASK)) 1000 return; 1001 1002 /* 1003 * Check whether we can free the pte page if the rest of the 1004 * entries are empty. Overlap with other regions have been 1005 * handled by the floor/ceiling check. 1006 */ 1007 ptep = pte_offset_kernel(pmdp, 0UL); 1008 for (i = 0; i < PTRS_PER_PTE; i++) { 1009 if (!pte_none(READ_ONCE(ptep[i]))) 1010 return; 1011 } 1012 1013 pmd_clear(pmdp); 1014 __flush_tlb_kernel_pgtable(start); 1015 free_hotplug_pgtable_page(virt_to_page(ptep)); 1016 } 1017 1018 static void free_empty_pmd_table(pud_t *pudp, unsigned long addr, 1019 unsigned long end, unsigned long floor, 1020 unsigned long ceiling) 1021 { 1022 pmd_t *pmdp, pmd; 1023 unsigned long i, next, start = addr; 1024 1025 do { 1026 next = pmd_addr_end(addr, end); 1027 pmdp = pmd_offset(pudp, addr); 1028 pmd = READ_ONCE(*pmdp); 1029 if (pmd_none(pmd)) 1030 continue; 1031 1032 WARN_ON(!pmd_present(pmd) || !pmd_table(pmd) || pmd_sect(pmd)); 1033 free_empty_pte_table(pmdp, addr, next, floor, ceiling); 1034 } while (addr = next, addr < end); 1035 1036 if (CONFIG_PGTABLE_LEVELS <= 2) 1037 return; 1038 1039 if (!pgtable_range_aligned(start, end, floor, ceiling, PUD_MASK)) 1040 return; 1041 1042 /* 1043 * Check whether we can free the pmd page if the rest of the 1044 * entries are empty. Overlap with other regions have been 1045 * handled by the floor/ceiling check. 1046 */ 1047 pmdp = pmd_offset(pudp, 0UL); 1048 for (i = 0; i < PTRS_PER_PMD; i++) { 1049 if (!pmd_none(READ_ONCE(pmdp[i]))) 1050 return; 1051 } 1052 1053 pud_clear(pudp); 1054 __flush_tlb_kernel_pgtable(start); 1055 free_hotplug_pgtable_page(virt_to_page(pmdp)); 1056 } 1057 1058 static void free_empty_pud_table(p4d_t *p4dp, unsigned long addr, 1059 unsigned long end, unsigned long floor, 1060 unsigned long ceiling) 1061 { 1062 pud_t *pudp, pud; 1063 unsigned long i, next, start = addr; 1064 1065 do { 1066 next = pud_addr_end(addr, end); 1067 pudp = pud_offset(p4dp, addr); 1068 pud = READ_ONCE(*pudp); 1069 if (pud_none(pud)) 1070 continue; 1071 1072 WARN_ON(!pud_present(pud) || !pud_table(pud) || pud_sect(pud)); 1073 free_empty_pmd_table(pudp, addr, next, floor, ceiling); 1074 } while (addr = next, addr < end); 1075 1076 if (CONFIG_PGTABLE_LEVELS <= 3) 1077 return; 1078 1079 if (!pgtable_range_aligned(start, end, floor, ceiling, PGDIR_MASK)) 1080 return; 1081 1082 /* 1083 * Check whether we can free the pud page if the rest of the 1084 * entries are empty. Overlap with other regions have been 1085 * handled by the floor/ceiling check. 1086 */ 1087 pudp = pud_offset(p4dp, 0UL); 1088 for (i = 0; i < PTRS_PER_PUD; i++) { 1089 if (!pud_none(READ_ONCE(pudp[i]))) 1090 return; 1091 } 1092 1093 p4d_clear(p4dp); 1094 __flush_tlb_kernel_pgtable(start); 1095 free_hotplug_pgtable_page(virt_to_page(pudp)); 1096 } 1097 1098 static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr, 1099 unsigned long end, unsigned long floor, 1100 unsigned long ceiling) 1101 { 1102 unsigned long next; 1103 p4d_t *p4dp, p4d; 1104 1105 do { 1106 next = p4d_addr_end(addr, end); 1107 p4dp = p4d_offset(pgdp, addr); 1108 p4d = READ_ONCE(*p4dp); 1109 if (p4d_none(p4d)) 1110 continue; 1111 1112 WARN_ON(!p4d_present(p4d)); 1113 free_empty_pud_table(p4dp, addr, next, floor, ceiling); 1114 } while (addr = next, addr < end); 1115 } 1116 1117 static void free_empty_tables(unsigned long addr, unsigned long end, 1118 unsigned long floor, unsigned long ceiling) 1119 { 1120 unsigned long next; 1121 pgd_t *pgdp, pgd; 1122 1123 do { 1124 next = pgd_addr_end(addr, end); 1125 pgdp = pgd_offset_k(addr); 1126 pgd = READ_ONCE(*pgdp); 1127 if (pgd_none(pgd)) 1128 continue; 1129 1130 WARN_ON(!pgd_present(pgd)); 1131 free_empty_p4d_table(pgdp, addr, next, floor, ceiling); 1132 } while (addr = next, addr < end); 1133 } 1134 #endif 1135 1136 void __meminit vmemmap_set_pmd(pmd_t *pmdp, void *p, int node, 1137 unsigned long addr, unsigned long next) 1138 { 1139 pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL)); 1140 } 1141 1142 int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node, 1143 unsigned long addr, unsigned long next) 1144 { 1145 vmemmap_verify((pte_t *)pmdp, node, addr, next); 1146 return 1; 1147 } 1148 1149 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, 1150 struct vmem_altmap *altmap) 1151 { 1152 WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END)); 1153 1154 if (!IS_ENABLED(CONFIG_ARM64_4K_PAGES)) 1155 return vmemmap_populate_basepages(start, end, node, altmap); 1156 else 1157 return vmemmap_populate_hugepages(start, end, node, altmap); 1158 } 1159 1160 #ifdef CONFIG_MEMORY_HOTPLUG 1161 void vmemmap_free(unsigned long start, unsigned long end, 1162 struct vmem_altmap *altmap) 1163 { 1164 WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END)); 1165 1166 unmap_hotplug_range(start, end, true, altmap); 1167 free_empty_tables(start, end, VMEMMAP_START, VMEMMAP_END); 1168 } 1169 #endif /* CONFIG_MEMORY_HOTPLUG */ 1170 1171 int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot) 1172 { 1173 pud_t new_pud = pfn_pud(__phys_to_pfn(phys), mk_pud_sect_prot(prot)); 1174 1175 /* Only allow permission changes for now */ 1176 if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)), 1177 pud_val(new_pud))) 1178 return 0; 1179 1180 VM_BUG_ON(phys & ~PUD_MASK); 1181 set_pud(pudp, new_pud); 1182 return 1; 1183 } 1184 1185 int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot) 1186 { 1187 pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), mk_pmd_sect_prot(prot)); 1188 1189 /* Only allow permission changes for now */ 1190 if (!pgattr_change_is_safe(READ_ONCE(pmd_val(*pmdp)), 1191 pmd_val(new_pmd))) 1192 return 0; 1193 1194 VM_BUG_ON(phys & ~PMD_MASK); 1195 set_pmd(pmdp, new_pmd); 1196 return 1; 1197 } 1198 1199 int pud_clear_huge(pud_t *pudp) 1200 { 1201 if (!pud_sect(READ_ONCE(*pudp))) 1202 return 0; 1203 pud_clear(pudp); 1204 return 1; 1205 } 1206 1207 int pmd_clear_huge(pmd_t *pmdp) 1208 { 1209 if (!pmd_sect(READ_ONCE(*pmdp))) 1210 return 0; 1211 pmd_clear(pmdp); 1212 return 1; 1213 } 1214 1215 int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr) 1216 { 1217 pte_t *table; 1218 pmd_t pmd; 1219 1220 pmd = READ_ONCE(*pmdp); 1221 1222 if (!pmd_table(pmd)) { 1223 VM_WARN_ON(1); 1224 return 1; 1225 } 1226 1227 table = pte_offset_kernel(pmdp, addr); 1228 pmd_clear(pmdp); 1229 __flush_tlb_kernel_pgtable(addr); 1230 pte_free_kernel(NULL, table); 1231 return 1; 1232 } 1233 1234 int pud_free_pmd_page(pud_t *pudp, unsigned long addr) 1235 { 1236 pmd_t *table; 1237 pmd_t *pmdp; 1238 pud_t pud; 1239 unsigned long next, end; 1240 1241 pud = READ_ONCE(*pudp); 1242 1243 if (!pud_table(pud)) { 1244 VM_WARN_ON(1); 1245 return 1; 1246 } 1247 1248 table = pmd_offset(pudp, addr); 1249 pmdp = table; 1250 next = addr; 1251 end = addr + PUD_SIZE; 1252 do { 1253 pmd_free_pte_page(pmdp, next); 1254 } while (pmdp++, next += PMD_SIZE, next != end); 1255 1256 pud_clear(pudp); 1257 __flush_tlb_kernel_pgtable(addr); 1258 pmd_free(NULL, table); 1259 return 1; 1260 } 1261 1262 #ifdef CONFIG_MEMORY_HOTPLUG 1263 static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) 1264 { 1265 unsigned long end = start + size; 1266 1267 WARN_ON(pgdir != init_mm.pgd); 1268 WARN_ON((start < PAGE_OFFSET) || (end > PAGE_END)); 1269 1270 unmap_hotplug_range(start, end, false, NULL); 1271 free_empty_tables(start, end, PAGE_OFFSET, PAGE_END); 1272 } 1273 1274 struct range arch_get_mappable_range(void) 1275 { 1276 struct range mhp_range; 1277 u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual)); 1278 u64 end_linear_pa = __pa(PAGE_END - 1); 1279 1280 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 1281 /* 1282 * Check for a wrap, it is possible because of randomized linear 1283 * mapping the start physical address is actually bigger than 1284 * the end physical address. In this case set start to zero 1285 * because [0, end_linear_pa] range must still be able to cover 1286 * all addressable physical addresses. 1287 */ 1288 if (start_linear_pa > end_linear_pa) 1289 start_linear_pa = 0; 1290 } 1291 1292 WARN_ON(start_linear_pa > end_linear_pa); 1293 1294 /* 1295 * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)] 1296 * accommodating both its ends but excluding PAGE_END. Max physical 1297 * range which can be mapped inside this linear mapping range, must 1298 * also be derived from its end points. 1299 */ 1300 mhp_range.start = start_linear_pa; 1301 mhp_range.end = end_linear_pa; 1302 1303 return mhp_range; 1304 } 1305 1306 int arch_add_memory(int nid, u64 start, u64 size, 1307 struct mhp_params *params) 1308 { 1309 int ret, flags = NO_EXEC_MAPPINGS; 1310 1311 VM_BUG_ON(!mhp_range_allowed(start, size, true)); 1312 1313 if (can_set_direct_map()) 1314 flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; 1315 1316 __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), 1317 size, params->pgprot, __pgd_pgtable_alloc, 1318 flags); 1319 1320 memblock_clear_nomap(start, size); 1321 1322 ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, 1323 params); 1324 if (ret) 1325 __remove_pgd_mapping(swapper_pg_dir, 1326 __phys_to_virt(start), size); 1327 else { 1328 max_pfn = PFN_UP(start + size); 1329 max_low_pfn = max_pfn; 1330 } 1331 1332 return ret; 1333 } 1334 1335 void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap) 1336 { 1337 unsigned long start_pfn = start >> PAGE_SHIFT; 1338 unsigned long nr_pages = size >> PAGE_SHIFT; 1339 1340 __remove_pages(start_pfn, nr_pages, altmap); 1341 __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); 1342 } 1343 1344 /* 1345 * This memory hotplug notifier helps prevent boot memory from being 1346 * inadvertently removed as it blocks pfn range offlining process in 1347 * __offline_pages(). Hence this prevents both offlining as well as 1348 * removal process for boot memory which is initially always online. 1349 * In future if and when boot memory could be removed, this notifier 1350 * should be dropped and free_hotplug_page_range() should handle any 1351 * reserved pages allocated during boot. 1352 */ 1353 static int prevent_bootmem_remove_notifier(struct notifier_block *nb, 1354 unsigned long action, void *data) 1355 { 1356 struct mem_section *ms; 1357 struct memory_notify *arg = data; 1358 unsigned long end_pfn = arg->start_pfn + arg->nr_pages; 1359 unsigned long pfn = arg->start_pfn; 1360 1361 if ((action != MEM_GOING_OFFLINE) && (action != MEM_OFFLINE)) 1362 return NOTIFY_OK; 1363 1364 for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { 1365 unsigned long start = PFN_PHYS(pfn); 1366 unsigned long end = start + (1UL << PA_SECTION_SHIFT); 1367 1368 ms = __pfn_to_section(pfn); 1369 if (!early_section(ms)) 1370 continue; 1371 1372 if (action == MEM_GOING_OFFLINE) { 1373 /* 1374 * Boot memory removal is not supported. Prevent 1375 * it via blocking any attempted offline request 1376 * for the boot memory and just report it. 1377 */ 1378 pr_warn("Boot memory [%lx %lx] offlining attempted\n", start, end); 1379 return NOTIFY_BAD; 1380 } else if (action == MEM_OFFLINE) { 1381 /* 1382 * This should have never happened. Boot memory 1383 * offlining should have been prevented by this 1384 * very notifier. Probably some memory removal 1385 * procedure might have changed which would then 1386 * require further debug. 1387 */ 1388 pr_err("Boot memory [%lx %lx] offlined\n", start, end); 1389 1390 /* 1391 * Core memory hotplug does not process a return 1392 * code from the notifier for MEM_OFFLINE events. 1393 * The error condition has been reported. Return 1394 * from here as if ignored. 1395 */ 1396 return NOTIFY_DONE; 1397 } 1398 } 1399 return NOTIFY_OK; 1400 } 1401 1402 static struct notifier_block prevent_bootmem_remove_nb = { 1403 .notifier_call = prevent_bootmem_remove_notifier, 1404 }; 1405 1406 /* 1407 * This ensures that boot memory sections on the platform are online 1408 * from early boot. Memory sections could not be prevented from being 1409 * offlined, unless for some reason they are not online to begin with. 1410 * This helps validate the basic assumption on which the above memory 1411 * event notifier works to prevent boot memory section offlining and 1412 * its possible removal. 1413 */ 1414 static void validate_bootmem_online(void) 1415 { 1416 phys_addr_t start, end, addr; 1417 struct mem_section *ms; 1418 u64 i; 1419 1420 /* 1421 * Scanning across all memblock might be expensive 1422 * on some big memory systems. Hence enable this 1423 * validation only with DEBUG_VM. 1424 */ 1425 if (!IS_ENABLED(CONFIG_DEBUG_VM)) 1426 return; 1427 1428 for_each_mem_range(i, &start, &end) { 1429 for (addr = start; addr < end; addr += (1UL << PA_SECTION_SHIFT)) { 1430 ms = __pfn_to_section(PHYS_PFN(addr)); 1431 1432 /* 1433 * All memory ranges in the system at this point 1434 * should have been marked as early sections. 1435 */ 1436 WARN_ON(!early_section(ms)); 1437 1438 /* 1439 * Memory notifier mechanism here to prevent boot 1440 * memory offlining depends on the fact that each 1441 * early section memory on the system is initially 1442 * online. Otherwise a given memory section which 1443 * is already offline will be overlooked and can 1444 * be removed completely. Call out such sections. 1445 */ 1446 if (!online_section(ms)) 1447 pr_err("Boot memory [%llx %llx] is offline, can be removed\n", 1448 addr, addr + (1UL << PA_SECTION_SHIFT)); 1449 } 1450 } 1451 } 1452 1453 static int __init prevent_bootmem_remove_init(void) 1454 { 1455 int ret = 0; 1456 1457 if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE)) 1458 return ret; 1459 1460 validate_bootmem_online(); 1461 ret = register_memory_notifier(&prevent_bootmem_remove_nb); 1462 if (ret) 1463 pr_err("%s: Notifier registration failed %d\n", __func__, ret); 1464 1465 return ret; 1466 } 1467 early_initcall(prevent_bootmem_remove_init); 1468 #endif 1469 1470 pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) 1471 { 1472 if (IS_ENABLED(CONFIG_ARM64_ERRATUM_2645198) && 1473 cpus_have_const_cap(ARM64_WORKAROUND_2645198)) { 1474 /* 1475 * Break-before-make (BBM) is required for all user space mappings 1476 * when the permission changes from executable to non-executable 1477 * in cases where cpu is affected with errata #2645198. 1478 */ 1479 if (pte_user_exec(READ_ONCE(*ptep))) 1480 return ptep_clear_flush(vma, addr, ptep); 1481 } 1482 return ptep_get_and_clear(vma->vm_mm, addr, ptep); 1483 } 1484 1485 void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, 1486 pte_t old_pte, pte_t pte) 1487 { 1488 set_pte_at(vma->vm_mm, addr, ptep, pte); 1489 }