1 #include <linux/gfp.h> 2 #include <linux/initrd.h> 3 #include <linux/ioport.h> 4 #include <linux/swap.h> 5 #include <linux/memblock.h> 6 #include <linux/swapfile.h> 7 #include <linux/swapops.h> 8 #include <linux/kmemleak.h> 9 #include <linux/sched/task.h> 10 11 #include <asm/set_memory.h> 12 #include <asm/e820/api.h> 13 #include <asm/init.h> 14 #include <asm/page.h> 15 #include <asm/page_types.h> 16 #include <asm/sections.h> 17 #include <asm/setup.h> 18 #include <asm/tlbflush.h> 19 #include <asm/tlb.h> 20 #include <asm/proto.h> 21 #include <asm/dma.h> /* for MAX_DMA_PFN */ 22 #include <asm/microcode.h> 23 #include <asm/kaslr.h> 24 #include <asm/hypervisor.h> 25 #include <asm/cpufeature.h> 26 #include <asm/pti.h> 27 #include <asm/text-patching.h> 28 #include <asm/memtype.h> 29 30 /* 31 * We need to define the tracepoints somewhere, and tlb.c 32 * is only compied when SMP=y. 33 */ 34 #define CREATE_TRACE_POINTS 35 #include <trace/events/tlb.h> 36 37 #include "mm_internal.h" 38 39 /* 40 * Tables translating between page_cache_type_t and pte encoding. 41 * 42 * The default values are defined statically as minimal supported mode; 43 * WC and WT fall back to UC-. pat_init() updates these values to support 44 * more cache modes, WC and WT, when it is safe to do so. See pat_init() 45 * for the details. Note, __early_ioremap() used during early boot-time 46 * takes pgprot_t (pte encoding) and does not use these tables. 47 * 48 * Index into __cachemode2pte_tbl[] is the cachemode. 49 * 50 * Index into __pte2cachemode_tbl[] are the caching attribute bits of the pte 51 * (_PAGE_PWT, _PAGE_PCD, _PAGE_PAT) at index bit positions 0, 1, 2. 52 */ 53 static uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = { 54 [_PAGE_CACHE_MODE_WB ] = 0 | 0 , 55 [_PAGE_CACHE_MODE_WC ] = 0 | _PAGE_PCD, 56 [_PAGE_CACHE_MODE_UC_MINUS] = 0 | _PAGE_PCD, 57 [_PAGE_CACHE_MODE_UC ] = _PAGE_PWT | _PAGE_PCD, 58 [_PAGE_CACHE_MODE_WT ] = 0 | _PAGE_PCD, 59 [_PAGE_CACHE_MODE_WP ] = 0 | _PAGE_PCD, 60 }; 61 62 unsigned long cachemode2protval(enum page_cache_mode pcm) 63 { 64 if (likely(pcm == 0)) 65 return 0; 66 return __cachemode2pte_tbl[pcm]; 67 } 68 EXPORT_SYMBOL(cachemode2protval); 69 70 static uint8_t __pte2cachemode_tbl[8] = { 71 [__pte2cm_idx( 0 | 0 | 0 )] = _PAGE_CACHE_MODE_WB, 72 [__pte2cm_idx(_PAGE_PWT | 0 | 0 )] = _PAGE_CACHE_MODE_UC_MINUS, 73 [__pte2cm_idx( 0 | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC_MINUS, 74 [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC, 75 [__pte2cm_idx( 0 | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_WB, 76 [__pte2cm_idx(_PAGE_PWT | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS, 77 [__pte2cm_idx(0 | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS, 78 [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC, 79 }; 80 81 /* Check that the write-protect PAT entry is set for write-protect */ 82 bool x86_has_pat_wp(void) 83 { 84 return __pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] == _PAGE_CACHE_MODE_WP; 85 } 86 87 enum page_cache_mode pgprot2cachemode(pgprot_t pgprot) 88 { 89 unsigned long masked; 90 91 masked = pgprot_val(pgprot) & _PAGE_CACHE_MASK; 92 if (likely(masked == 0)) 93 return 0; 94 return __pte2cachemode_tbl[__pte2cm_idx(masked)]; 95 } 96 97 static unsigned long __initdata pgt_buf_start; 98 static unsigned long __initdata pgt_buf_end; 99 static unsigned long __initdata pgt_buf_top; 100 101 static unsigned long min_pfn_mapped; 102 103 static bool __initdata can_use_brk_pgt = true; 104 105 /* 106 * Pages returned are already directly mapped. 107 * 108 * Changing that is likely to break Xen, see commit: 109 * 110 * 279b706 x86,xen: introduce x86_init.mapping.pagetable_reserve 111 * 112 * for detailed information. 113 */ 114 __ref void *alloc_low_pages(unsigned int num) 115 { 116 unsigned long pfn; 117 int i; 118 119 if (after_bootmem) { 120 unsigned int order; 121 122 order = get_order((unsigned long)num << PAGE_SHIFT); 123 return (void *)__get_free_pages(GFP_ATOMIC | __GFP_ZERO, order); 124 } 125 126 if ((pgt_buf_end + num) > pgt_buf_top || !can_use_brk_pgt) { 127 unsigned long ret = 0; 128 129 if (min_pfn_mapped < max_pfn_mapped) { 130 ret = memblock_find_in_range( 131 min_pfn_mapped << PAGE_SHIFT, 132 max_pfn_mapped << PAGE_SHIFT, 133 PAGE_SIZE * num , PAGE_SIZE); 134 } 135 if (ret) 136 memblock_reserve(ret, PAGE_SIZE * num); 137 else if (can_use_brk_pgt) 138 ret = __pa(extend_brk(PAGE_SIZE * num, PAGE_SIZE)); 139 140 if (!ret) 141 panic("alloc_low_pages: can not alloc memory"); 142 143 pfn = ret >> PAGE_SHIFT; 144 } else { 145 pfn = pgt_buf_end; 146 pgt_buf_end += num; 147 } 148 149 for (i = 0; i < num; i++) { 150 void *adr; 151 152 adr = __va((pfn + i) << PAGE_SHIFT); 153 clear_page(adr); 154 } 155 156 return __va(pfn << PAGE_SHIFT); 157 } 158 159 /* 160 * By default need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS. 161 * With KASLR memory randomization, depending on the machine e820 memory 162 * and the PUD alignment. We may need twice more pages when KASLR memory 163 * randomization is enabled. 164 */ 165 #ifndef CONFIG_RANDOMIZE_MEMORY 166 #define INIT_PGD_PAGE_COUNT 6 167 #else 168 #define INIT_PGD_PAGE_COUNT 12 169 #endif 170 #define INIT_PGT_BUF_SIZE (INIT_PGD_PAGE_COUNT * PAGE_SIZE) 171 RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); 172 void __init early_alloc_pgt_buf(void) 173 { 174 unsigned long tables = INIT_PGT_BUF_SIZE; 175 phys_addr_t base; 176 177 base = __pa(extend_brk(tables, PAGE_SIZE)); 178 179 pgt_buf_start = base >> PAGE_SHIFT; 180 pgt_buf_end = pgt_buf_start; 181 pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT); 182 } 183 184 int after_bootmem; 185 186 early_param_on_off("gbpages", "nogbpages", direct_gbpages, CONFIG_X86_DIRECT_GBPAGES); 187 188 struct map_range { 189 unsigned long start; 190 unsigned long end; 191 unsigned page_size_mask; 192 }; 193 194 static int page_size_mask; 195 196 /* 197 * Save some of cr4 feature set we're using (e.g. Pentium 4MB 198 * enable and PPro Global page enable), so that any CPU's that boot 199 * up after us can get the correct flags. Invoked on the boot CPU. 200 */ 201 static inline void cr4_set_bits_and_update_boot(unsigned long mask) 202 { 203 mmu_cr4_features |= mask; 204 if (trampoline_cr4_features) 205 *trampoline_cr4_features = mmu_cr4_features; 206 cr4_set_bits(mask); 207 } 208 209 static void __init probe_page_size_mask(void) 210 { 211 /* 212 * For pagealloc debugging, identity mapping will use small pages. 213 * This will simplify cpa(), which otherwise needs to support splitting 214 * large pages into small in interrupt context, etc. 215 */ 216 if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled()) 217 page_size_mask |= 1 << PG_LEVEL_2M; 218 else 219 direct_gbpages = 0; 220 221 /* Enable PSE if available */ 222 if (boot_cpu_has(X86_FEATURE_PSE)) 223 cr4_set_bits_and_update_boot(X86_CR4_PSE); 224 225 /* Enable PGE if available */ 226 __supported_pte_mask &= ~_PAGE_GLOBAL; 227 if (boot_cpu_has(X86_FEATURE_PGE)) { 228 cr4_set_bits_and_update_boot(X86_CR4_PGE); 229 __supported_pte_mask |= _PAGE_GLOBAL; 230 } 231 232 /* By the default is everything supported: */ 233 __default_kernel_pte_mask = __supported_pte_mask; 234 /* Except when with PTI where the kernel is mostly non-Global: */ 235 if (cpu_feature_enabled(X86_FEATURE_PTI)) 236 __default_kernel_pte_mask &= ~_PAGE_GLOBAL; 237 238 /* Enable 1 GB linear kernel mappings if available: */ 239 if (direct_gbpages && boot_cpu_has(X86_FEATURE_GBPAGES)) { 240 printk(KERN_INFO "Using GB pages for direct mapping\n"); 241 page_size_mask |= 1 << PG_LEVEL_1G; 242 } else { 243 direct_gbpages = 0; 244 } 245 } 246 247 static void setup_pcid(void) 248 { 249 if (!IS_ENABLED(CONFIG_X86_64)) 250 return; 251 252 if (!boot_cpu_has(X86_FEATURE_PCID)) 253 return; 254 255 if (boot_cpu_has(X86_FEATURE_PGE)) { 256 /* 257 * This can't be cr4_set_bits_and_update_boot() -- the 258 * trampoline code can't handle CR4.PCIDE and it wouldn't 259 * do any good anyway. Despite the name, 260 * cr4_set_bits_and_update_boot() doesn't actually cause 261 * the bits in question to remain set all the way through 262 * the secondary boot asm. 263 * 264 * Instead, we brute-force it and set CR4.PCIDE manually in 265 * start_secondary(). 266 */ 267 cr4_set_bits(X86_CR4_PCIDE); 268 269 /* 270 * INVPCID's single-context modes (2/3) only work if we set 271 * X86_CR4_PCIDE, *and* we INVPCID support. It's unusable 272 * on systems that have X86_CR4_PCIDE clear, or that have 273 * no INVPCID support at all. 274 */ 275 if (boot_cpu_has(X86_FEATURE_INVPCID)) 276 setup_force_cpu_cap(X86_FEATURE_INVPCID_SINGLE); 277 } else { 278 /* 279 * flush_tlb_all(), as currently implemented, won't work if 280 * PCID is on but PGE is not. Since that combination 281 * doesn't exist on real hardware, there's no reason to try 282 * to fully support it, but it's polite to avoid corrupting 283 * data if we're on an improperly configured VM. 284 */ 285 setup_clear_cpu_cap(X86_FEATURE_PCID); 286 } 287 } 288 289 #ifdef CONFIG_X86_32 290 #define NR_RANGE_MR 3 291 #else /* CONFIG_X86_64 */ 292 #define NR_RANGE_MR 5 293 #endif 294 295 static int __meminit save_mr(struct map_range *mr, int nr_range, 296 unsigned long start_pfn, unsigned long end_pfn, 297 unsigned long page_size_mask) 298 { 299 if (start_pfn < end_pfn) { 300 if (nr_range >= NR_RANGE_MR) 301 panic("run out of range for init_memory_mapping\n"); 302 mr[nr_range].start = start_pfn<<PAGE_SHIFT; 303 mr[nr_range].end = end_pfn<<PAGE_SHIFT; 304 mr[nr_range].page_size_mask = page_size_mask; 305 nr_range++; 306 } 307 308 return nr_range; 309 } 310 311 /* 312 * adjust the page_size_mask for small range to go with 313 * big page size instead small one if nearby are ram too. 314 */ 315 static void __ref adjust_range_page_size_mask(struct map_range *mr, 316 int nr_range) 317 { 318 int i; 319 320 for (i = 0; i < nr_range; i++) { 321 if ((page_size_mask & (1<<PG_LEVEL_2M)) && 322 !(mr[i].page_size_mask & (1<<PG_LEVEL_2M))) { 323 unsigned long start = round_down(mr[i].start, PMD_SIZE); 324 unsigned long end = round_up(mr[i].end, PMD_SIZE); 325 326 #ifdef CONFIG_X86_32 327 if ((end >> PAGE_SHIFT) > max_low_pfn) 328 continue; 329 #endif 330 331 if (memblock_is_region_memory(start, end - start)) 332 mr[i].page_size_mask |= 1<<PG_LEVEL_2M; 333 } 334 if ((page_size_mask & (1<<PG_LEVEL_1G)) && 335 !(mr[i].page_size_mask & (1<<PG_LEVEL_1G))) { 336 unsigned long start = round_down(mr[i].start, PUD_SIZE); 337 unsigned long end = round_up(mr[i].end, PUD_SIZE); 338 339 if (memblock_is_region_memory(start, end - start)) 340 mr[i].page_size_mask |= 1<<PG_LEVEL_1G; 341 } 342 } 343 } 344 345 static const char *page_size_string(struct map_range *mr) 346 { 347 static const char str_1g[] = "1G"; 348 static const char str_2m[] = "2M"; 349 static const char str_4m[] = "4M"; 350 static const char str_4k[] = "4k"; 351 352 if (mr->page_size_mask & (1<<PG_LEVEL_1G)) 353 return str_1g; 354 /* 355 * 32-bit without PAE has a 4M large page size. 356 * PG_LEVEL_2M is misnamed, but we can at least 357 * print out the right size in the string. 358 */ 359 if (IS_ENABLED(CONFIG_X86_32) && 360 !IS_ENABLED(CONFIG_X86_PAE) && 361 mr->page_size_mask & (1<<PG_LEVEL_2M)) 362 return str_4m; 363 364 if (mr->page_size_mask & (1<<PG_LEVEL_2M)) 365 return str_2m; 366 367 return str_4k; 368 } 369 370 static int __meminit split_mem_range(struct map_range *mr, int nr_range, 371 unsigned long start, 372 unsigned long end) 373 { 374 unsigned long start_pfn, end_pfn, limit_pfn; 375 unsigned long pfn; 376 int i; 377 378 limit_pfn = PFN_DOWN(end); 379 380 /* head if not big page alignment ? */ 381 pfn = start_pfn = PFN_DOWN(start); 382 #ifdef CONFIG_X86_32 383 /* 384 * Don't use a large page for the first 2/4MB of memory 385 * because there are often fixed size MTRRs in there 386 * and overlapping MTRRs into large pages can cause 387 * slowdowns. 388 */ 389 if (pfn == 0) 390 end_pfn = PFN_DOWN(PMD_SIZE); 391 else 392 end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE)); 393 #else /* CONFIG_X86_64 */ 394 end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE)); 395 #endif 396 if (end_pfn > limit_pfn) 397 end_pfn = limit_pfn; 398 if (start_pfn < end_pfn) { 399 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0); 400 pfn = end_pfn; 401 } 402 403 /* big page (2M) range */ 404 start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE)); 405 #ifdef CONFIG_X86_32 406 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE)); 407 #else /* CONFIG_X86_64 */ 408 end_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE)); 409 if (end_pfn > round_down(limit_pfn, PFN_DOWN(PMD_SIZE))) 410 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE)); 411 #endif 412 413 if (start_pfn < end_pfn) { 414 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 415 page_size_mask & (1<<PG_LEVEL_2M)); 416 pfn = end_pfn; 417 } 418 419 #ifdef CONFIG_X86_64 420 /* big page (1G) range */ 421 start_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE)); 422 end_pfn = round_down(limit_pfn, PFN_DOWN(PUD_SIZE)); 423 if (start_pfn < end_pfn) { 424 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 425 page_size_mask & 426 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G))); 427 pfn = end_pfn; 428 } 429 430 /* tail is not big page (1G) alignment */ 431 start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE)); 432 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE)); 433 if (start_pfn < end_pfn) { 434 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 435 page_size_mask & (1<<PG_LEVEL_2M)); 436 pfn = end_pfn; 437 } 438 #endif 439 440 /* tail is not big page (2M) alignment */ 441 start_pfn = pfn; 442 end_pfn = limit_pfn; 443 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0); 444 445 if (!after_bootmem) 446 adjust_range_page_size_mask(mr, nr_range); 447 448 /* try to merge same page size and continuous */ 449 for (i = 0; nr_range > 1 && i < nr_range - 1; i++) { 450 unsigned long old_start; 451 if (mr[i].end != mr[i+1].start || 452 mr[i].page_size_mask != mr[i+1].page_size_mask) 453 continue; 454 /* move it */ 455 old_start = mr[i].start; 456 memmove(&mr[i], &mr[i+1], 457 (nr_range - 1 - i) * sizeof(struct map_range)); 458 mr[i--].start = old_start; 459 nr_range--; 460 } 461 462 for (i = 0; i < nr_range; i++) 463 pr_debug(" [mem %#010lx-%#010lx] page %s\n", 464 mr[i].start, mr[i].end - 1, 465 page_size_string(&mr[i])); 466 467 return nr_range; 468 } 469 470 struct range pfn_mapped[E820_MAX_ENTRIES]; 471 int nr_pfn_mapped; 472 473 static void add_pfn_range_mapped(unsigned long start_pfn, unsigned long end_pfn) 474 { 475 nr_pfn_mapped = add_range_with_merge(pfn_mapped, E820_MAX_ENTRIES, 476 nr_pfn_mapped, start_pfn, end_pfn); 477 nr_pfn_mapped = clean_sort_range(pfn_mapped, E820_MAX_ENTRIES); 478 479 max_pfn_mapped = max(max_pfn_mapped, end_pfn); 480 481 if (start_pfn < (1UL<<(32-PAGE_SHIFT))) 482 max_low_pfn_mapped = max(max_low_pfn_mapped, 483 min(end_pfn, 1UL<<(32-PAGE_SHIFT))); 484 } 485 486 bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn) 487 { 488 int i; 489 490 for (i = 0; i < nr_pfn_mapped; i++) 491 if ((start_pfn >= pfn_mapped[i].start) && 492 (end_pfn <= pfn_mapped[i].end)) 493 return true; 494 495 return false; 496 } 497 498 /* 499 * Setup the direct mapping of the physical memory at PAGE_OFFSET. 500 * This runs before bootmem is initialized and gets pages directly from 501 * the physical memory. To access them they are temporarily mapped. 502 */ 503 unsigned long __ref init_memory_mapping(unsigned long start, 504 unsigned long end, pgprot_t prot) 505 { 506 struct map_range mr[NR_RANGE_MR]; 507 unsigned long ret = 0; 508 int nr_range, i; 509 510 pr_debug("init_memory_mapping: [mem %#010lx-%#010lx]\n", 511 start, end - 1); 512 513 memset(mr, 0, sizeof(mr)); 514 nr_range = split_mem_range(mr, 0, start, end); 515 516 for (i = 0; i < nr_range; i++) 517 ret = kernel_physical_mapping_init(mr[i].start, mr[i].end, 518 mr[i].page_size_mask, 519 prot); 520 521 add_pfn_range_mapped(start >> PAGE_SHIFT, ret >> PAGE_SHIFT); 522 523 return ret >> PAGE_SHIFT; 524 } 525 526 /* 527 * We need to iterate through the E820 memory map and create direct mappings 528 * for only E820_TYPE_RAM and E820_KERN_RESERVED regions. We cannot simply 529 * create direct mappings for all pfns from [0 to max_low_pfn) and 530 * [4GB to max_pfn) because of possible memory holes in high addresses 531 * that cannot be marked as UC by fixed/variable range MTRRs. 532 * Depending on the alignment of E820 ranges, this may possibly result 533 * in using smaller size (i.e. 4K instead of 2M or 1G) page tables. 534 * 535 * init_mem_mapping() calls init_range_memory_mapping() with big range. 536 * That range would have hole in the middle or ends, and only ram parts 537 * will be mapped in init_range_memory_mapping(). 538 */ 539 static unsigned long __init init_range_memory_mapping( 540 unsigned long r_start, 541 unsigned long r_end) 542 { 543 unsigned long start_pfn, end_pfn; 544 unsigned long mapped_ram_size = 0; 545 int i; 546 547 for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) { 548 u64 start = clamp_val(PFN_PHYS(start_pfn), r_start, r_end); 549 u64 end = clamp_val(PFN_PHYS(end_pfn), r_start, r_end); 550 if (start >= end) 551 continue; 552 553 /* 554 * if it is overlapping with brk pgt, we need to 555 * alloc pgt buf from memblock instead. 556 */ 557 can_use_brk_pgt = max(start, (u64)pgt_buf_end<<PAGE_SHIFT) >= 558 min(end, (u64)pgt_buf_top<<PAGE_SHIFT); 559 init_memory_mapping(start, end, PAGE_KERNEL); 560 mapped_ram_size += end - start; 561 can_use_brk_pgt = true; 562 } 563 564 return mapped_ram_size; 565 } 566 567 static unsigned long __init get_new_step_size(unsigned long step_size) 568 { 569 /* 570 * Initial mapped size is PMD_SIZE (2M). 571 * We can not set step_size to be PUD_SIZE (1G) yet. 572 * In worse case, when we cross the 1G boundary, and 573 * PG_LEVEL_2M is not set, we will need 1+1+512 pages (2M + 8k) 574 * to map 1G range with PTE. Hence we use one less than the 575 * difference of page table level shifts. 576 * 577 * Don't need to worry about overflow in the top-down case, on 32bit, 578 * when step_size is 0, round_down() returns 0 for start, and that 579 * turns it into 0x100000000ULL. 580 * In the bottom-up case, round_up(x, 0) returns 0 though too, which 581 * needs to be taken into consideration by the code below. 582 */ 583 return step_size << (PMD_SHIFT - PAGE_SHIFT - 1); 584 } 585 586 /** 587 * memory_map_top_down - Map [map_start, map_end) top down 588 * @map_start: start address of the target memory range 589 * @map_end: end address of the target memory range 590 * 591 * This function will setup direct mapping for memory range 592 * [map_start, map_end) in top-down. That said, the page tables 593 * will be allocated at the end of the memory, and we map the 594 * memory in top-down. 595 */ 596 static void __init memory_map_top_down(unsigned long map_start, 597 unsigned long map_end) 598 { 599 unsigned long real_end, start, last_start; 600 unsigned long step_size; 601 unsigned long addr; 602 unsigned long mapped_ram_size = 0; 603 604 /* xen has big range in reserved near end of ram, skip it at first.*/ 605 addr = memblock_find_in_range(map_start, map_end, PMD_SIZE, PMD_SIZE); 606 real_end = addr + PMD_SIZE; 607 608 /* step_size need to be small so pgt_buf from BRK could cover it */ 609 step_size = PMD_SIZE; 610 max_pfn_mapped = 0; /* will get exact value next */ 611 min_pfn_mapped = real_end >> PAGE_SHIFT; 612 last_start = start = real_end; 613 614 /* 615 * We start from the top (end of memory) and go to the bottom. 616 * The memblock_find_in_range() gets us a block of RAM from the 617 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages 618 * for page table. 619 */ 620 while (last_start > map_start) { 621 if (last_start > step_size) { 622 start = round_down(last_start - 1, step_size); 623 if (start < map_start) 624 start = map_start; 625 } else 626 start = map_start; 627 mapped_ram_size += init_range_memory_mapping(start, 628 last_start); 629 last_start = start; 630 min_pfn_mapped = last_start >> PAGE_SHIFT; 631 if (mapped_ram_size >= step_size) 632 step_size = get_new_step_size(step_size); 633 } 634 635 if (real_end < map_end) 636 init_range_memory_mapping(real_end, map_end); 637 } 638 639 /** 640 * memory_map_bottom_up - Map [map_start, map_end) bottom up 641 * @map_start: start address of the target memory range 642 * @map_end: end address of the target memory range 643 * 644 * This function will setup direct mapping for memory range 645 * [map_start, map_end) in bottom-up. Since we have limited the 646 * bottom-up allocation above the kernel, the page tables will 647 * be allocated just above the kernel and we map the memory 648 * in [map_start, map_end) in bottom-up. 649 */ 650 static void __init memory_map_bottom_up(unsigned long map_start, 651 unsigned long map_end) 652 { 653 unsigned long next, start; 654 unsigned long mapped_ram_size = 0; 655 /* step_size need to be small so pgt_buf from BRK could cover it */ 656 unsigned long step_size = PMD_SIZE; 657 658 start = map_start; 659 min_pfn_mapped = start >> PAGE_SHIFT; 660 661 /* 662 * We start from the bottom (@map_start) and go to the top (@map_end). 663 * The memblock_find_in_range() gets us a block of RAM from the 664 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages 665 * for page table. 666 */ 667 while (start < map_end) { 668 if (step_size && map_end - start > step_size) { 669 next = round_up(start + 1, step_size); 670 if (next > map_end) 671 next = map_end; 672 } else { 673 next = map_end; 674 } 675 676 mapped_ram_size += init_range_memory_mapping(start, next); 677 start = next; 678 679 if (mapped_ram_size >= step_size) 680 step_size = get_new_step_size(step_size); 681 } 682 } 683 684 /* 685 * The real mode trampoline, which is required for bootstrapping CPUs 686 * occupies only a small area under the low 1MB. See reserve_real_mode() 687 * for details. 688 * 689 * If KASLR is disabled the first PGD entry of the direct mapping is copied 690 * to map the real mode trampoline. 691 * 692 * If KASLR is enabled, copy only the PUD which covers the low 1MB 693 * area. This limits the randomization granularity to 1GB for both 4-level 694 * and 5-level paging. 695 */ 696 static void __init init_trampoline(void) 697 { 698 #ifdef CONFIG_X86_64 699 if (!kaslr_memory_enabled()) 700 trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)]; 701 else 702 init_trampoline_kaslr(); 703 #endif 704 } 705 706 void __init init_mem_mapping(void) 707 { 708 unsigned long end; 709 710 pti_check_boottime_disable(); 711 probe_page_size_mask(); 712 setup_pcid(); 713 714 #ifdef CONFIG_X86_64 715 end = max_pfn << PAGE_SHIFT; 716 #else 717 end = max_low_pfn << PAGE_SHIFT; 718 #endif 719 720 /* the ISA range is always mapped regardless of memory holes */ 721 init_memory_mapping(0, ISA_END_ADDRESS, PAGE_KERNEL); 722 723 /* Init the trampoline, possibly with KASLR memory offset */ 724 init_trampoline(); 725 726 /* 727 * If the allocation is in bottom-up direction, we setup direct mapping 728 * in bottom-up, otherwise we setup direct mapping in top-down. 729 */ 730 if (memblock_bottom_up()) { 731 unsigned long kernel_end = __pa_symbol(_end); 732 733 /* 734 * we need two separate calls here. This is because we want to 735 * allocate page tables above the kernel. So we first map 736 * [kernel_end, end) to make memory above the kernel be mapped 737 * as soon as possible. And then use page tables allocated above 738 * the kernel to map [ISA_END_ADDRESS, kernel_end). 739 */ 740 memory_map_bottom_up(kernel_end, end); 741 memory_map_bottom_up(ISA_END_ADDRESS, kernel_end); 742 } else { 743 memory_map_top_down(ISA_END_ADDRESS, end); 744 } 745 746 #ifdef CONFIG_X86_64 747 if (max_pfn > max_low_pfn) { 748 /* can we preseve max_low_pfn ?*/ 749 max_low_pfn = max_pfn; 750 } 751 #else 752 early_ioremap_page_table_range_init(); 753 #endif 754 755 load_cr3(swapper_pg_dir); 756 __flush_tlb_all(); 757 758 x86_init.hyper.init_mem_mapping(); 759 760 early_memtest(0, max_pfn_mapped << PAGE_SHIFT); 761 } 762 763 /* 764 * Initialize an mm_struct to be used during poking and a pointer to be used 765 * during patching. 766 */ 767 void __init poking_init(void) 768 { 769 spinlock_t *ptl; 770 pte_t *ptep; 771 772 poking_mm = copy_init_mm(); 773 BUG_ON(!poking_mm); 774 775 /* 776 * Randomize the poking address, but make sure that the following page 777 * will be mapped at the same PMD. We need 2 pages, so find space for 3, 778 * and adjust the address if the PMD ends after the first one. 779 */ 780 poking_addr = TASK_UNMAPPED_BASE; 781 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) 782 poking_addr += (kaslr_get_random_long("Poking") & PAGE_MASK) % 783 (TASK_SIZE - TASK_UNMAPPED_BASE - 3 * PAGE_SIZE); 784 785 if (((poking_addr + PAGE_SIZE) & ~PMD_MASK) == 0) 786 poking_addr += PAGE_SIZE; 787 788 /* 789 * We need to trigger the allocation of the page-tables that will be 790 * needed for poking now. Later, poking may be performed in an atomic 791 * section, which might cause allocation to fail. 792 */ 793 ptep = get_locked_pte(poking_mm, poking_addr, &ptl); 794 BUG_ON(!ptep); 795 pte_unmap_unlock(ptep, ptl); 796 } 797 798 /* 799 * devmem_is_allowed() checks to see if /dev/mem access to a certain address 800 * is valid. The argument is a physical page number. 801 * 802 * On x86, access has to be given to the first megabyte of RAM because that 803 * area traditionally contains BIOS code and data regions used by X, dosemu, 804 * and similar apps. Since they map the entire memory range, the whole range 805 * must be allowed (for mapping), but any areas that would otherwise be 806 * disallowed are flagged as being "zero filled" instead of rejected. 807 * Access has to be given to non-kernel-ram areas as well, these contain the 808 * PCI mmio resources as well as potential bios/acpi data regions. 809 */ 810 int devmem_is_allowed(unsigned long pagenr) 811 { 812 if (region_intersects(PFN_PHYS(pagenr), PAGE_SIZE, 813 IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE) 814 != REGION_DISJOINT) { 815 /* 816 * For disallowed memory regions in the low 1MB range, 817 * request that the page be shown as all zeros. 818 */ 819 if (pagenr < 256) 820 return 2; 821 822 return 0; 823 } 824 825 /* 826 * This must follow RAM test, since System RAM is considered a 827 * restricted resource under CONFIG_STRICT_IOMEM. 828 */ 829 if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) { 830 /* Low 1MB bypasses iomem restrictions. */ 831 if (pagenr < 256) 832 return 1; 833 834 return 0; 835 } 836 837 return 1; 838 } 839 840 void free_init_pages(const char *what, unsigned long begin, unsigned long end) 841 { 842 unsigned long begin_aligned, end_aligned; 843 844 /* Make sure boundaries are page aligned */ 845 begin_aligned = PAGE_ALIGN(begin); 846 end_aligned = end & PAGE_MASK; 847 848 if (WARN_ON(begin_aligned != begin || end_aligned != end)) { 849 begin = begin_aligned; 850 end = end_aligned; 851 } 852 853 if (begin >= end) 854 return; 855 856 /* 857 * If debugging page accesses then do not free this memory but 858 * mark them not present - any buggy init-section access will 859 * create a kernel page fault: 860 */ 861 if (debug_pagealloc_enabled()) { 862 pr_info("debug: unmapping init [mem %#010lx-%#010lx]\n", 863 begin, end - 1); 864 /* 865 * Inform kmemleak about the hole in the memory since the 866 * corresponding pages will be unmapped. 867 */ 868 kmemleak_free_part((void *)begin, end - begin); 869 set_memory_np(begin, (end - begin) >> PAGE_SHIFT); 870 } else { 871 /* 872 * We just marked the kernel text read only above, now that 873 * we are going to free part of that, we need to make that 874 * writeable and non-executable first. 875 */ 876 set_memory_nx(begin, (end - begin) >> PAGE_SHIFT); 877 set_memory_rw(begin, (end - begin) >> PAGE_SHIFT); 878 879 free_reserved_area((void *)begin, (void *)end, 880 POISON_FREE_INITMEM, what); 881 } 882 } 883 884 /* 885 * begin/end can be in the direct map or the "high kernel mapping" 886 * used for the kernel image only. free_init_pages() will do the 887 * right thing for either kind of address. 888 */ 889 void free_kernel_image_pages(const char *what, void *begin, void *end) 890 { 891 unsigned long begin_ul = (unsigned long)begin; 892 unsigned long end_ul = (unsigned long)end; 893 unsigned long len_pages = (end_ul - begin_ul) >> PAGE_SHIFT; 894 895 free_init_pages(what, begin_ul, end_ul); 896 897 /* 898 * PTI maps some of the kernel into userspace. For performance, 899 * this includes some kernel areas that do not contain secrets. 900 * Those areas might be adjacent to the parts of the kernel image 901 * being freed, which may contain secrets. Remove the "high kernel 902 * image mapping" for these freed areas, ensuring they are not even 903 * potentially vulnerable to Meltdown regardless of the specific 904 * optimizations PTI is currently using. 905 * 906 * The "noalias" prevents unmapping the direct map alias which is 907 * needed to access the freed pages. 908 * 909 * This is only valid for 64bit kernels. 32bit has only one mapping 910 * which can't be treated in this way for obvious reasons. 911 */ 912 if (IS_ENABLED(CONFIG_X86_64) && cpu_feature_enabled(X86_FEATURE_PTI)) 913 set_memory_np_noalias(begin_ul, len_pages); 914 } 915 916 void __ref free_initmem(void) 917 { 918 e820__reallocate_tables(); 919 920 mem_encrypt_free_decrypted_mem(); 921 922 free_kernel_image_pages("unused kernel image (initmem)", 923 &__init_begin, &__init_end); 924 } 925 926 #ifdef CONFIG_BLK_DEV_INITRD 927 void __init free_initrd_mem(unsigned long start, unsigned long end) 928 { 929 /* 930 * end could be not aligned, and We can not align that, 931 * decompresser could be confused by aligned initrd_end 932 * We already reserve the end partial page before in 933 * - i386_start_kernel() 934 * - x86_64_start_kernel() 935 * - relocate_initrd() 936 * So here We can do PAGE_ALIGN() safely to get partial page to be freed 937 */ 938 free_init_pages("initrd", start, PAGE_ALIGN(end)); 939 } 940 #endif 941 942 /* 943 * Calculate the precise size of the DMA zone (first 16 MB of RAM), 944 * and pass it to the MM layer - to help it set zone watermarks more 945 * accurately. 946 * 947 * Done on 64-bit systems only for the time being, although 32-bit systems 948 * might benefit from this as well. 949 */ 950 void __init memblock_find_dma_reserve(void) 951 { 952 #ifdef CONFIG_X86_64 953 u64 nr_pages = 0, nr_free_pages = 0; 954 unsigned long start_pfn, end_pfn; 955 phys_addr_t start_addr, end_addr; 956 int i; 957 u64 u; 958 959 /* 960 * Iterate over all memory ranges (free and reserved ones alike), 961 * to calculate the total number of pages in the first 16 MB of RAM: 962 */ 963 nr_pages = 0; 964 for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) { 965 start_pfn = min(start_pfn, MAX_DMA_PFN); 966 end_pfn = min(end_pfn, MAX_DMA_PFN); 967 968 nr_pages += end_pfn - start_pfn; 969 } 970 971 /* 972 * Iterate over free memory ranges to calculate the number of free 973 * pages in the DMA zone, while not counting potential partial 974 * pages at the beginning or the end of the range: 975 */ 976 nr_free_pages = 0; 977 for_each_free_mem_range(u, NUMA_NO_NODE, MEMBLOCK_NONE, &start_addr, &end_addr, NULL) { 978 start_pfn = min_t(unsigned long, PFN_UP(start_addr), MAX_DMA_PFN); 979 end_pfn = min_t(unsigned long, PFN_DOWN(end_addr), MAX_DMA_PFN); 980 981 if (start_pfn < end_pfn) 982 nr_free_pages += end_pfn - start_pfn; 983 } 984 985 set_dma_reserve(nr_pages - nr_free_pages); 986 #endif 987 } 988 989 void __init zone_sizes_init(void) 990 { 991 unsigned long max_zone_pfns[MAX_NR_ZONES]; 992 993 memset(max_zone_pfns, 0, sizeof(max_zone_pfns)); 994 995 #ifdef CONFIG_ZONE_DMA 996 max_zone_pfns[ZONE_DMA] = min(MAX_DMA_PFN, max_low_pfn); 997 #endif 998 #ifdef CONFIG_ZONE_DMA32 999 max_zone_pfns[ZONE_DMA32] = min(MAX_DMA32_PFN, max_low_pfn); 1000 #endif 1001 max_zone_pfns[ZONE_NORMAL] = max_low_pfn; 1002 #ifdef CONFIG_HIGHMEM 1003 max_zone_pfns[ZONE_HIGHMEM] = max_pfn; 1004 #endif 1005 1006 free_area_init(max_zone_pfns); 1007 } 1008 1009 __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate) = { 1010 .loaded_mm = &init_mm, 1011 .next_asid = 1, 1012 .cr4 = ~0UL, /* fail hard if we screw up cr4 shadow initialization */ 1013 }; 1014 1015 void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache) 1016 { 1017 /* entry 0 MUST be WB (hardwired to speed up translations) */ 1018 BUG_ON(!entry && cache != _PAGE_CACHE_MODE_WB); 1019 1020 __cachemode2pte_tbl[cache] = __cm_idx2pte(entry); 1021 __pte2cachemode_tbl[entry] = cache; 1022 } 1023 1024 #ifdef CONFIG_SWAP 1025 unsigned long max_swapfile_size(void) 1026 { 1027 unsigned long pages; 1028 1029 pages = generic_max_swapfile_size(); 1030 1031 if (boot_cpu_has_bug(X86_BUG_L1TF) && l1tf_mitigation != L1TF_MITIGATION_OFF) { 1032 /* Limit the swap file size to MAX_PA/2 for L1TF workaround */ 1033 unsigned long long l1tf_limit = l1tf_pfn_limit(); 1034 /* 1035 * We encode swap offsets also with 3 bits below those for pfn 1036 * which makes the usable limit higher. 1037 */ 1038 #if CONFIG_PGTABLE_LEVELS > 2 1039 l1tf_limit <<= PAGE_SHIFT - SWP_OFFSET_FIRST_BIT; 1040 #endif 1041 pages = min_t(unsigned long long, l1tf_limit, pages); 1042 } 1043 return pages; 1044 } 1045 #endif 1046