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 */
  53static 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
  62unsigned long cachemode2protval(enum page_cache_mode pcm)
  63{
  64	if (likely(pcm == 0))
  65		return 0;
  66	return __cachemode2pte_tbl[pcm];
  67}
  68EXPORT_SYMBOL(cachemode2protval);
  69
  70static 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 */
  82bool x86_has_pat_wp(void)
  83{
  84	return __pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] == _PAGE_CACHE_MODE_WP;
  85}
  86
  87enum 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
  97static unsigned long __initdata pgt_buf_start;
  98static unsigned long __initdata pgt_buf_end;
  99static unsigned long __initdata pgt_buf_top;
 100
 101static unsigned long min_pfn_mapped;
 102
 103static 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)
 171RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
 172void  __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
 184int after_bootmem;
 185
 186early_param_on_off("gbpages", "nogbpages", direct_gbpages, CONFIG_X86_DIRECT_GBPAGES);
 187
 188struct map_range {
 189	unsigned long start;
 190	unsigned long end;
 191	unsigned page_size_mask;
 192};
 193
 194static 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 */
 201static 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
 209static 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
 247static 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
 295static 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 */
 315static 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
 345static 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
 370static 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
 470struct range pfn_mapped[E820_MAX_ENTRIES];
 471int nr_pfn_mapped;
 472
 473static 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
 486bool 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 */
 503unsigned 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 */
 539static 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
 567static 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 */
 596static 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 */
 650static 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 */
 696static 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
 706void __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 */
 767void __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 */
 810int 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
 840void 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 */
 889void 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
 916void __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
 927void __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 */
 950void __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
 989void __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
1015void 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
1025unsigned 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