arch/x86/mm/init.c

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

DEFINITIONS
