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/cpu_device_id.h>
  13#include <asm/e820/api.h>
  14#include <asm/init.h>
  15#include <asm/page.h>
  16#include <asm/page_types.h>
  17#include <asm/sections.h>
  18#include <asm/setup.h>
  19#include <asm/tlbflush.h>
  20#include <asm/tlb.h>
  21#include <asm/proto.h>
  22#include <asm/dma.h>		/* for MAX_DMA_PFN */
 
  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#include <asm/paravirt.h>
  30
  31/*
  32 * We need to define the tracepoints somewhere, and tlb.c
  33 * is only compiled when SMP=y.
  34 */
 
  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/*
  82 * Check that the write-protect PAT entry is set for write-protect.
  83 * To do this without making assumptions how PAT has been set up (Xen has
  84 * another layout than the kernel), translate the _PAGE_CACHE_MODE_WP cache
  85 * mode via the __cachemode2pte_tbl[] into protection bits (those protection
  86 * bits will select a cache mode of WP or better), and then translate the
  87 * protection bits back into the cache mode using __pte2cm_idx() and the
  88 * __pte2cachemode_tbl[] array. This will return the really used cache mode.
  89 */
  90bool x86_has_pat_wp(void)
  91{
  92	uint16_t prot = __cachemode2pte_tbl[_PAGE_CACHE_MODE_WP];
  93
  94	return __pte2cachemode_tbl[__pte2cm_idx(prot)] == _PAGE_CACHE_MODE_WP;
  95}
  96
  97enum page_cache_mode pgprot2cachemode(pgprot_t pgprot)
  98{
  99	unsigned long masked;
 100
 101	masked = pgprot_val(pgprot) & _PAGE_CACHE_MASK;
 102	if (likely(masked == 0))
 103		return 0;
 104	return __pte2cachemode_tbl[__pte2cm_idx(masked)];
 105}
 106
 107static unsigned long __initdata pgt_buf_start;
 108static unsigned long __initdata pgt_buf_end;
 109static unsigned long __initdata pgt_buf_top;
 110
 111static unsigned long min_pfn_mapped;
 112
 113static bool __initdata can_use_brk_pgt = true;
 114
 115/*
 116 * Pages returned are already directly mapped.
 117 *
 118 * Changing that is likely to break Xen, see commit:
 119 *
 120 *    279b706 x86,xen: introduce x86_init.mapping.pagetable_reserve
 121 *
 122 * for detailed information.
 123 */
 124__ref void *alloc_low_pages(unsigned int num)
 125{
 126	unsigned long pfn;
 127	int i;
 128
 129	if (after_bootmem) {
 130		unsigned int order;
 131
 132		order = get_order((unsigned long)num << PAGE_SHIFT);
 133		return (void *)__get_free_pages(GFP_ATOMIC | __GFP_ZERO, order);
 134	}
 135
 136	if ((pgt_buf_end + num) > pgt_buf_top || !can_use_brk_pgt) {
 137		unsigned long ret = 0;
 138
 139		if (min_pfn_mapped < max_pfn_mapped) {
 140			ret = memblock_phys_alloc_range(
 141					PAGE_SIZE * num, PAGE_SIZE,
 142					min_pfn_mapped << PAGE_SHIFT,
 143					max_pfn_mapped << PAGE_SHIFT);
 144		}
 145		if (!ret && can_use_brk_pgt)
 146			ret = __pa(extend_brk(PAGE_SIZE * num, PAGE_SIZE));
 147
 148		if (!ret)
 149			panic("alloc_low_pages: can not alloc memory");
 150
 151		pfn = ret >> PAGE_SHIFT;
 152	} else {
 153		pfn = pgt_buf_end;
 154		pgt_buf_end += num;
 
 
 155	}
 156
 157	for (i = 0; i < num; i++) {
 158		void *adr;
 159
 160		adr = __va((pfn + i) << PAGE_SHIFT);
 161		clear_page(adr);
 162	}
 163
 164	return __va(pfn << PAGE_SHIFT);
 165}
 166
 167/*
 168 * By default need to be able to allocate page tables below PGD firstly for
 169 * the 0-ISA_END_ADDRESS range and secondly for the initial PMD_SIZE mapping.
 170 * With KASLR memory randomization, depending on the machine e820 memory and the
 171 * PUD alignment, twice that many pages may be needed when KASLR memory
 172 * randomization is enabled.
 173 */
 174
 175#ifndef CONFIG_X86_5LEVEL
 176#define INIT_PGD_PAGE_TABLES    3
 177#else
 178#define INIT_PGD_PAGE_TABLES    4
 179#endif
 180
 181#ifndef CONFIG_RANDOMIZE_MEMORY
 182#define INIT_PGD_PAGE_COUNT      (2 * INIT_PGD_PAGE_TABLES)
 183#else
 184#define INIT_PGD_PAGE_COUNT      (4 * INIT_PGD_PAGE_TABLES)
 185#endif
 186
 187#define INIT_PGT_BUF_SIZE	(INIT_PGD_PAGE_COUNT * PAGE_SIZE)
 188RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
 189void  __init early_alloc_pgt_buf(void)
 190{
 191	unsigned long tables = INIT_PGT_BUF_SIZE;
 192	phys_addr_t base;
 193
 194	base = __pa(extend_brk(tables, PAGE_SIZE));
 195
 196	pgt_buf_start = base >> PAGE_SHIFT;
 197	pgt_buf_end = pgt_buf_start;
 198	pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
 199}
 200
 201int after_bootmem;
 202
 203early_param_on_off("gbpages", "nogbpages", direct_gbpages, CONFIG_X86_DIRECT_GBPAGES);
 204
 205struct map_range {
 206	unsigned long start;
 207	unsigned long end;
 208	unsigned page_size_mask;
 209};
 210
 211static int page_size_mask;
 212
 213/*
 214 * Save some of cr4 feature set we're using (e.g.  Pentium 4MB
 215 * enable and PPro Global page enable), so that any CPU's that boot
 216 * up after us can get the correct flags. Invoked on the boot CPU.
 217 */
 218static inline void cr4_set_bits_and_update_boot(unsigned long mask)
 219{
 220	mmu_cr4_features |= mask;
 221	if (trampoline_cr4_features)
 222		*trampoline_cr4_features = mmu_cr4_features;
 223	cr4_set_bits(mask);
 224}
 225
 226static void __init probe_page_size_mask(void)
 227{
 228	/*
 229	 * For pagealloc debugging, identity mapping will use small pages.
 230	 * This will simplify cpa(), which otherwise needs to support splitting
 231	 * large pages into small in interrupt context, etc.
 232	 */
 233	if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled())
 234		page_size_mask |= 1 << PG_LEVEL_2M;
 235	else
 236		direct_gbpages = 0;
 237
 238	/* Enable PSE if available */
 239	if (boot_cpu_has(X86_FEATURE_PSE))
 240		cr4_set_bits_and_update_boot(X86_CR4_PSE);
 241
 242	/* Enable PGE if available */
 243	__supported_pte_mask &= ~_PAGE_GLOBAL;
 244	if (boot_cpu_has(X86_FEATURE_PGE)) {
 245		cr4_set_bits_and_update_boot(X86_CR4_PGE);
 246		__supported_pte_mask |= _PAGE_GLOBAL;
 247	}
 248
 249	/* By the default is everything supported: */
 250	__default_kernel_pte_mask = __supported_pte_mask;
 251	/* Except when with PTI where the kernel is mostly non-Global: */
 252	if (cpu_feature_enabled(X86_FEATURE_PTI))
 253		__default_kernel_pte_mask &= ~_PAGE_GLOBAL;
 254
 255	/* Enable 1 GB linear kernel mappings if available: */
 256	if (direct_gbpages && boot_cpu_has(X86_FEATURE_GBPAGES)) {
 257		printk(KERN_INFO "Using GB pages for direct mapping\n");
 258		page_size_mask |= 1 << PG_LEVEL_1G;
 259	} else {
 260		direct_gbpages = 0;
 261	}
 262}
 263
 264#define INTEL_MATCH(_model) { .vendor  = X86_VENDOR_INTEL,	\
 265			      .family  = 6,			\
 266			      .model = _model,			\
 267			    }
 268/*
 269 * INVLPG may not properly flush Global entries
 270 * on these CPUs when PCIDs are enabled.
 271 */
 272static const struct x86_cpu_id invlpg_miss_ids[] = {
 273	INTEL_MATCH(INTEL_FAM6_ALDERLAKE   ),
 274	INTEL_MATCH(INTEL_FAM6_ALDERLAKE_L ),
 275	INTEL_MATCH(INTEL_FAM6_ATOM_GRACEMONT ),
 276	INTEL_MATCH(INTEL_FAM6_RAPTORLAKE  ),
 277	INTEL_MATCH(INTEL_FAM6_RAPTORLAKE_P),
 278	INTEL_MATCH(INTEL_FAM6_RAPTORLAKE_S),
 279	{}
 280};
 281
 282static void setup_pcid(void)
 283{
 284	if (!IS_ENABLED(CONFIG_X86_64))
 285		return;
 286
 287	if (!boot_cpu_has(X86_FEATURE_PCID))
 288		return;
 289
 290	if (x86_match_cpu(invlpg_miss_ids)) {
 291		pr_info("Incomplete global flushes, disabling PCID");
 292		setup_clear_cpu_cap(X86_FEATURE_PCID);
 293		return;
 294	}
 295
 296	if (boot_cpu_has(X86_FEATURE_PGE)) {
 297		/*
 298		 * This can't be cr4_set_bits_and_update_boot() -- the
 299		 * trampoline code can't handle CR4.PCIDE and it wouldn't
 300		 * do any good anyway.  Despite the name,
 301		 * cr4_set_bits_and_update_boot() doesn't actually cause
 302		 * the bits in question to remain set all the way through
 303		 * the secondary boot asm.
 304		 *
 305		 * Instead, we brute-force it and set CR4.PCIDE manually in
 306		 * start_secondary().
 307		 */
 308		cr4_set_bits(X86_CR4_PCIDE);
 
 
 
 
 
 
 
 
 
 309	} else {
 310		/*
 311		 * flush_tlb_all(), as currently implemented, won't work if
 312		 * PCID is on but PGE is not.  Since that combination
 313		 * doesn't exist on real hardware, there's no reason to try
 314		 * to fully support it, but it's polite to avoid corrupting
 315		 * data if we're on an improperly configured VM.
 316		 */
 317		setup_clear_cpu_cap(X86_FEATURE_PCID);
 318	}
 319}
 320
 321#ifdef CONFIG_X86_32
 322#define NR_RANGE_MR 3
 323#else /* CONFIG_X86_64 */
 324#define NR_RANGE_MR 5
 325#endif
 326
 327static int __meminit save_mr(struct map_range *mr, int nr_range,
 328			     unsigned long start_pfn, unsigned long end_pfn,
 329			     unsigned long page_size_mask)
 330{
 331	if (start_pfn < end_pfn) {
 332		if (nr_range >= NR_RANGE_MR)
 333			panic("run out of range for init_memory_mapping\n");
 334		mr[nr_range].start = start_pfn<<PAGE_SHIFT;
 335		mr[nr_range].end   = end_pfn<<PAGE_SHIFT;
 336		mr[nr_range].page_size_mask = page_size_mask;
 337		nr_range++;
 338	}
 339
 340	return nr_range;
 341}
 342
 343/*
 344 * adjust the page_size_mask for small range to go with
 345 *	big page size instead small one if nearby are ram too.
 346 */
 347static void __ref adjust_range_page_size_mask(struct map_range *mr,
 348							 int nr_range)
 349{
 350	int i;
 351
 352	for (i = 0; i < nr_range; i++) {
 353		if ((page_size_mask & (1<<PG_LEVEL_2M)) &&
 354		    !(mr[i].page_size_mask & (1<<PG_LEVEL_2M))) {
 355			unsigned long start = round_down(mr[i].start, PMD_SIZE);
 356			unsigned long end = round_up(mr[i].end, PMD_SIZE);
 357
 358#ifdef CONFIG_X86_32
 359			if ((end >> PAGE_SHIFT) > max_low_pfn)
 360				continue;
 361#endif
 362
 363			if (memblock_is_region_memory(start, end - start))
 364				mr[i].page_size_mask |= 1<<PG_LEVEL_2M;
 365		}
 366		if ((page_size_mask & (1<<PG_LEVEL_1G)) &&
 367		    !(mr[i].page_size_mask & (1<<PG_LEVEL_1G))) {
 368			unsigned long start = round_down(mr[i].start, PUD_SIZE);
 369			unsigned long end = round_up(mr[i].end, PUD_SIZE);
 370
 371			if (memblock_is_region_memory(start, end - start))
 372				mr[i].page_size_mask |= 1<<PG_LEVEL_1G;
 373		}
 374	}
 375}
 376
 377static const char *page_size_string(struct map_range *mr)
 378{
 379	static const char str_1g[] = "1G";
 380	static const char str_2m[] = "2M";
 381	static const char str_4m[] = "4M";
 382	static const char str_4k[] = "4k";
 383
 384	if (mr->page_size_mask & (1<<PG_LEVEL_1G))
 385		return str_1g;
 386	/*
 387	 * 32-bit without PAE has a 4M large page size.
 388	 * PG_LEVEL_2M is misnamed, but we can at least
 389	 * print out the right size in the string.
 390	 */
 391	if (IS_ENABLED(CONFIG_X86_32) &&
 392	    !IS_ENABLED(CONFIG_X86_PAE) &&
 393	    mr->page_size_mask & (1<<PG_LEVEL_2M))
 394		return str_4m;
 395
 396	if (mr->page_size_mask & (1<<PG_LEVEL_2M))
 397		return str_2m;
 398
 399	return str_4k;
 400}
 401
 402static int __meminit split_mem_range(struct map_range *mr, int nr_range,
 403				     unsigned long start,
 404				     unsigned long end)
 405{
 406	unsigned long start_pfn, end_pfn, limit_pfn;
 407	unsigned long pfn;
 408	int i;
 409
 410	limit_pfn = PFN_DOWN(end);
 411
 412	/* head if not big page alignment ? */
 413	pfn = start_pfn = PFN_DOWN(start);
 414#ifdef CONFIG_X86_32
 415	/*
 416	 * Don't use a large page for the first 2/4MB of memory
 417	 * because there are often fixed size MTRRs in there
 418	 * and overlapping MTRRs into large pages can cause
 419	 * slowdowns.
 420	 */
 421	if (pfn == 0)
 422		end_pfn = PFN_DOWN(PMD_SIZE);
 423	else
 424		end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
 425#else /* CONFIG_X86_64 */
 426	end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
 427#endif
 428	if (end_pfn > limit_pfn)
 429		end_pfn = limit_pfn;
 430	if (start_pfn < end_pfn) {
 431		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
 432		pfn = end_pfn;
 433	}
 434
 435	/* big page (2M) range */
 436	start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
 437#ifdef CONFIG_X86_32
 438	end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
 439#else /* CONFIG_X86_64 */
 440	end_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE));
 441	if (end_pfn > round_down(limit_pfn, PFN_DOWN(PMD_SIZE)))
 442		end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
 443#endif
 444
 445	if (start_pfn < end_pfn) {
 446		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 447				page_size_mask & (1<<PG_LEVEL_2M));
 448		pfn = end_pfn;
 449	}
 450
 451#ifdef CONFIG_X86_64
 452	/* big page (1G) range */
 453	start_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE));
 454	end_pfn = round_down(limit_pfn, PFN_DOWN(PUD_SIZE));
 455	if (start_pfn < end_pfn) {
 456		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 457				page_size_mask &
 458				 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
 459		pfn = end_pfn;
 460	}
 461
 462	/* tail is not big page (1G) alignment */
 463	start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
 464	end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
 465	if (start_pfn < end_pfn) {
 466		nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 467				page_size_mask & (1<<PG_LEVEL_2M));
 468		pfn = end_pfn;
 469	}
 470#endif
 471
 472	/* tail is not big page (2M) alignment */
 473	start_pfn = pfn;
 474	end_pfn = limit_pfn;
 475	nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
 476
 477	if (!after_bootmem)
 478		adjust_range_page_size_mask(mr, nr_range);
 479
 480	/* try to merge same page size and continuous */
 481	for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
 482		unsigned long old_start;
 483		if (mr[i].end != mr[i+1].start ||
 484		    mr[i].page_size_mask != mr[i+1].page_size_mask)
 485			continue;
 486		/* move it */
 487		old_start = mr[i].start;
 488		memmove(&mr[i], &mr[i+1],
 489			(nr_range - 1 - i) * sizeof(struct map_range));
 490		mr[i--].start = old_start;
 491		nr_range--;
 492	}
 493
 494	for (i = 0; i < nr_range; i++)
 495		pr_debug(" [mem %#010lx-%#010lx] page %s\n",
 496				mr[i].start, mr[i].end - 1,
 497				page_size_string(&mr[i]));
 498
 499	return nr_range;
 500}
 501
 502struct range pfn_mapped[E820_MAX_ENTRIES];
 503int nr_pfn_mapped;
 504
 505static void add_pfn_range_mapped(unsigned long start_pfn, unsigned long end_pfn)
 506{
 507	nr_pfn_mapped = add_range_with_merge(pfn_mapped, E820_MAX_ENTRIES,
 508					     nr_pfn_mapped, start_pfn, end_pfn);
 509	nr_pfn_mapped = clean_sort_range(pfn_mapped, E820_MAX_ENTRIES);
 510
 511	max_pfn_mapped = max(max_pfn_mapped, end_pfn);
 512
 513	if (start_pfn < (1UL<<(32-PAGE_SHIFT)))
 514		max_low_pfn_mapped = max(max_low_pfn_mapped,
 515					 min(end_pfn, 1UL<<(32-PAGE_SHIFT)));
 516}
 517
 518bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn)
 519{
 520	int i;
 521
 522	for (i = 0; i < nr_pfn_mapped; i++)
 523		if ((start_pfn >= pfn_mapped[i].start) &&
 524		    (end_pfn <= pfn_mapped[i].end))
 525			return true;
 526
 527	return false;
 528}
 529
 530/*
 531 * Setup the direct mapping of the physical memory at PAGE_OFFSET.
 532 * This runs before bootmem is initialized and gets pages directly from
 533 * the physical memory. To access them they are temporarily mapped.
 534 */
 535unsigned long __ref init_memory_mapping(unsigned long start,
 536					unsigned long end, pgprot_t prot)
 537{
 538	struct map_range mr[NR_RANGE_MR];
 539	unsigned long ret = 0;
 540	int nr_range, i;
 541
 542	pr_debug("init_memory_mapping: [mem %#010lx-%#010lx]\n",
 543	       start, end - 1);
 544
 545	memset(mr, 0, sizeof(mr));
 546	nr_range = split_mem_range(mr, 0, start, end);
 547
 548	for (i = 0; i < nr_range; i++)
 549		ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
 550						   mr[i].page_size_mask,
 551						   prot);
 552
 553	add_pfn_range_mapped(start >> PAGE_SHIFT, ret >> PAGE_SHIFT);
 554
 555	return ret >> PAGE_SHIFT;
 556}
 557
 558/*
 559 * We need to iterate through the E820 memory map and create direct mappings
 560 * for only E820_TYPE_RAM and E820_KERN_RESERVED regions. We cannot simply
 561 * create direct mappings for all pfns from [0 to max_low_pfn) and
 562 * [4GB to max_pfn) because of possible memory holes in high addresses
 563 * that cannot be marked as UC by fixed/variable range MTRRs.
 564 * Depending on the alignment of E820 ranges, this may possibly result
 565 * in using smaller size (i.e. 4K instead of 2M or 1G) page tables.
 566 *
 567 * init_mem_mapping() calls init_range_memory_mapping() with big range.
 568 * That range would have hole in the middle or ends, and only ram parts
 569 * will be mapped in init_range_memory_mapping().
 570 */
 571static unsigned long __init init_range_memory_mapping(
 572					   unsigned long r_start,
 573					   unsigned long r_end)
 574{
 575	unsigned long start_pfn, end_pfn;
 576	unsigned long mapped_ram_size = 0;
 577	int i;
 578
 579	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
 580		u64 start = clamp_val(PFN_PHYS(start_pfn), r_start, r_end);
 581		u64 end = clamp_val(PFN_PHYS(end_pfn), r_start, r_end);
 582		if (start >= end)
 583			continue;
 584
 585		/*
 586		 * if it is overlapping with brk pgt, we need to
 587		 * alloc pgt buf from memblock instead.
 588		 */
 589		can_use_brk_pgt = max(start, (u64)pgt_buf_end<<PAGE_SHIFT) >=
 590				    min(end, (u64)pgt_buf_top<<PAGE_SHIFT);
 591		init_memory_mapping(start, end, PAGE_KERNEL);
 592		mapped_ram_size += end - start;
 593		can_use_brk_pgt = true;
 594	}
 595
 596	return mapped_ram_size;
 597}
 598
 599static unsigned long __init get_new_step_size(unsigned long step_size)
 600{
 601	/*
 602	 * Initial mapped size is PMD_SIZE (2M).
 603	 * We can not set step_size to be PUD_SIZE (1G) yet.
 604	 * In worse case, when we cross the 1G boundary, and
 605	 * PG_LEVEL_2M is not set, we will need 1+1+512 pages (2M + 8k)
 606	 * to map 1G range with PTE. Hence we use one less than the
 607	 * difference of page table level shifts.
 608	 *
 609	 * Don't need to worry about overflow in the top-down case, on 32bit,
 610	 * when step_size is 0, round_down() returns 0 for start, and that
 611	 * turns it into 0x100000000ULL.
 612	 * In the bottom-up case, round_up(x, 0) returns 0 though too, which
 613	 * needs to be taken into consideration by the code below.
 614	 */
 615	return step_size << (PMD_SHIFT - PAGE_SHIFT - 1);
 616}
 617
 618/**
 619 * memory_map_top_down - Map [map_start, map_end) top down
 620 * @map_start: start address of the target memory range
 621 * @map_end: end address of the target memory range
 622 *
 623 * This function will setup direct mapping for memory range
 624 * [map_start, map_end) in top-down. That said, the page tables
 625 * will be allocated at the end of the memory, and we map the
 626 * memory in top-down.
 627 */
 628static void __init memory_map_top_down(unsigned long map_start,
 629				       unsigned long map_end)
 630{
 631	unsigned long real_end, last_start;
 632	unsigned long step_size;
 633	unsigned long addr;
 634	unsigned long mapped_ram_size = 0;
 635
 636	/*
 637	 * Systems that have many reserved areas near top of the memory,
 638	 * e.g. QEMU with less than 1G RAM and EFI enabled, or Xen, will
 639	 * require lots of 4K mappings which may exhaust pgt_buf.
 640	 * Start with top-most PMD_SIZE range aligned at PMD_SIZE to ensure
 641	 * there is enough mapped memory that can be allocated from
 642	 * memblock.
 643	 */
 644	addr = memblock_phys_alloc_range(PMD_SIZE, PMD_SIZE, map_start,
 645					 map_end);
 646	memblock_phys_free(addr, PMD_SIZE);
 647	real_end = addr + PMD_SIZE;
 648
 649	/* step_size need to be small so pgt_buf from BRK could cover it */
 650	step_size = PMD_SIZE;
 651	max_pfn_mapped = 0; /* will get exact value next */
 652	min_pfn_mapped = real_end >> PAGE_SHIFT;
 653	last_start = real_end;
 654
 655	/*
 656	 * We start from the top (end of memory) and go to the bottom.
 657	 * The memblock_find_in_range() gets us a block of RAM from the
 658	 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
 659	 * for page table.
 660	 */
 661	while (last_start > map_start) {
 662		unsigned long start;
 663
 664		if (last_start > step_size) {
 665			start = round_down(last_start - 1, step_size);
 666			if (start < map_start)
 667				start = map_start;
 668		} else
 669			start = map_start;
 670		mapped_ram_size += init_range_memory_mapping(start,
 671							last_start);
 672		last_start = start;
 673		min_pfn_mapped = last_start >> PAGE_SHIFT;
 674		if (mapped_ram_size >= step_size)
 675			step_size = get_new_step_size(step_size);
 676	}
 677
 678	if (real_end < map_end)
 679		init_range_memory_mapping(real_end, map_end);
 680}
 681
 682/**
 683 * memory_map_bottom_up - Map [map_start, map_end) bottom up
 684 * @map_start: start address of the target memory range
 685 * @map_end: end address of the target memory range
 686 *
 687 * This function will setup direct mapping for memory range
 688 * [map_start, map_end) in bottom-up. Since we have limited the
 689 * bottom-up allocation above the kernel, the page tables will
 690 * be allocated just above the kernel and we map the memory
 691 * in [map_start, map_end) in bottom-up.
 692 */
 693static void __init memory_map_bottom_up(unsigned long map_start,
 694					unsigned long map_end)
 695{
 696	unsigned long next, start;
 697	unsigned long mapped_ram_size = 0;
 698	/* step_size need to be small so pgt_buf from BRK could cover it */
 699	unsigned long step_size = PMD_SIZE;
 700
 701	start = map_start;
 702	min_pfn_mapped = start >> PAGE_SHIFT;
 703
 704	/*
 705	 * We start from the bottom (@map_start) and go to the top (@map_end).
 706	 * The memblock_find_in_range() gets us a block of RAM from the
 707	 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
 708	 * for page table.
 709	 */
 710	while (start < map_end) {
 711		if (step_size && map_end - start > step_size) {
 712			next = round_up(start + 1, step_size);
 713			if (next > map_end)
 714				next = map_end;
 715		} else {
 716			next = map_end;
 717		}
 718
 719		mapped_ram_size += init_range_memory_mapping(start, next);
 720		start = next;
 721
 722		if (mapped_ram_size >= step_size)
 723			step_size = get_new_step_size(step_size);
 724	}
 725}
 726
 727/*
 728 * The real mode trampoline, which is required for bootstrapping CPUs
 729 * occupies only a small area under the low 1MB.  See reserve_real_mode()
 730 * for details.
 731 *
 732 * If KASLR is disabled the first PGD entry of the direct mapping is copied
 733 * to map the real mode trampoline.
 734 *
 735 * If KASLR is enabled, copy only the PUD which covers the low 1MB
 736 * area. This limits the randomization granularity to 1GB for both 4-level
 737 * and 5-level paging.
 738 */
 739static void __init init_trampoline(void)
 740{
 741#ifdef CONFIG_X86_64
 742	/*
 743	 * The code below will alias kernel page-tables in the user-range of the
 744	 * address space, including the Global bit. So global TLB entries will
 745	 * be created when using the trampoline page-table.
 746	 */
 747	if (!kaslr_memory_enabled())
 748		trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)];
 749	else
 750		init_trampoline_kaslr();
 751#endif
 752}
 753
 754void __init init_mem_mapping(void)
 755{
 756	unsigned long end;
 757
 758	pti_check_boottime_disable();
 759	probe_page_size_mask();
 760	setup_pcid();
 761
 762#ifdef CONFIG_X86_64
 763	end = max_pfn << PAGE_SHIFT;
 764#else
 765	end = max_low_pfn << PAGE_SHIFT;
 766#endif
 767
 768	/* the ISA range is always mapped regardless of memory holes */
 769	init_memory_mapping(0, ISA_END_ADDRESS, PAGE_KERNEL);
 770
 771	/* Init the trampoline, possibly with KASLR memory offset */
 772	init_trampoline();
 773
 774	/*
 775	 * If the allocation is in bottom-up direction, we setup direct mapping
 776	 * in bottom-up, otherwise we setup direct mapping in top-down.
 777	 */
 778	if (memblock_bottom_up()) {
 779		unsigned long kernel_end = __pa_symbol(_end);
 780
 781		/*
 782		 * we need two separate calls here. This is because we want to
 783		 * allocate page tables above the kernel. So we first map
 784		 * [kernel_end, end) to make memory above the kernel be mapped
 785		 * as soon as possible. And then use page tables allocated above
 786		 * the kernel to map [ISA_END_ADDRESS, kernel_end).
 787		 */
 788		memory_map_bottom_up(kernel_end, end);
 789		memory_map_bottom_up(ISA_END_ADDRESS, kernel_end);
 790	} else {
 791		memory_map_top_down(ISA_END_ADDRESS, end);
 792	}
 793
 794#ifdef CONFIG_X86_64
 795	if (max_pfn > max_low_pfn) {
 796		/* can we preserve max_low_pfn ?*/
 797		max_low_pfn = max_pfn;
 798	}
 799#else
 800	early_ioremap_page_table_range_init();
 801#endif
 802
 803	load_cr3(swapper_pg_dir);
 804	__flush_tlb_all();
 805
 806	x86_init.hyper.init_mem_mapping();
 807
 808	early_memtest(0, max_pfn_mapped << PAGE_SHIFT);
 809}
 810
 811/*
 812 * Initialize an mm_struct to be used during poking and a pointer to be used
 813 * during patching.
 814 */
 815void __init poking_init(void)
 816{
 817	spinlock_t *ptl;
 818	pte_t *ptep;
 819
 820	poking_mm = mm_alloc();
 821	BUG_ON(!poking_mm);
 822
 823	/* Xen PV guests need the PGD to be pinned. */
 824	paravirt_enter_mmap(poking_mm);
 825
 826	/*
 827	 * Randomize the poking address, but make sure that the following page
 828	 * will be mapped at the same PMD. We need 2 pages, so find space for 3,
 829	 * and adjust the address if the PMD ends after the first one.
 830	 */
 831	poking_addr = TASK_UNMAPPED_BASE;
 832	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
 833		poking_addr += (kaslr_get_random_long("Poking") & PAGE_MASK) %
 834			(TASK_SIZE - TASK_UNMAPPED_BASE - 3 * PAGE_SIZE);
 835
 836	if (((poking_addr + PAGE_SIZE) & ~PMD_MASK) == 0)
 837		poking_addr += PAGE_SIZE;
 838
 839	/*
 840	 * We need to trigger the allocation of the page-tables that will be
 841	 * needed for poking now. Later, poking may be performed in an atomic
 842	 * section, which might cause allocation to fail.
 843	 */
 844	ptep = get_locked_pte(poking_mm, poking_addr, &ptl);
 845	BUG_ON(!ptep);
 846	pte_unmap_unlock(ptep, ptl);
 847}
 848
 849/*
 850 * devmem_is_allowed() checks to see if /dev/mem access to a certain address
 851 * is valid. The argument is a physical page number.
 852 *
 853 * On x86, access has to be given to the first megabyte of RAM because that
 854 * area traditionally contains BIOS code and data regions used by X, dosemu,
 855 * and similar apps. Since they map the entire memory range, the whole range
 856 * must be allowed (for mapping), but any areas that would otherwise be
 857 * disallowed are flagged as being "zero filled" instead of rejected.
 858 * Access has to be given to non-kernel-ram areas as well, these contain the
 859 * PCI mmio resources as well as potential bios/acpi data regions.
 860 */
 861int devmem_is_allowed(unsigned long pagenr)
 862{
 863	if (region_intersects(PFN_PHYS(pagenr), PAGE_SIZE,
 864				IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE)
 865			!= REGION_DISJOINT) {
 866		/*
 867		 * For disallowed memory regions in the low 1MB range,
 868		 * request that the page be shown as all zeros.
 869		 */
 870		if (pagenr < 256)
 871			return 2;
 872
 873		return 0;
 874	}
 875
 876	/*
 877	 * This must follow RAM test, since System RAM is considered a
 878	 * restricted resource under CONFIG_STRICT_DEVMEM.
 879	 */
 880	if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) {
 881		/* Low 1MB bypasses iomem restrictions. */
 882		if (pagenr < 256)
 883			return 1;
 884
 885		return 0;
 886	}
 887
 888	return 1;
 889}
 890
 891void free_init_pages(const char *what, unsigned long begin, unsigned long end)
 892{
 893	unsigned long begin_aligned, end_aligned;
 894
 895	/* Make sure boundaries are page aligned */
 896	begin_aligned = PAGE_ALIGN(begin);
 897	end_aligned   = end & PAGE_MASK;
 898
 899	if (WARN_ON(begin_aligned != begin || end_aligned != end)) {
 900		begin = begin_aligned;
 901		end   = end_aligned;
 902	}
 903
 904	if (begin >= end)
 905		return;
 906
 907	/*
 908	 * If debugging page accesses then do not free this memory but
 909	 * mark them not present - any buggy init-section access will
 910	 * create a kernel page fault:
 911	 */
 912	if (debug_pagealloc_enabled()) {
 913		pr_info("debug: unmapping init [mem %#010lx-%#010lx]\n",
 914			begin, end - 1);
 915		/*
 916		 * Inform kmemleak about the hole in the memory since the
 917		 * corresponding pages will be unmapped.
 918		 */
 919		kmemleak_free_part((void *)begin, end - begin);
 920		set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
 921	} else {
 922		/*
 923		 * We just marked the kernel text read only above, now that
 924		 * we are going to free part of that, we need to make that
 925		 * writeable and non-executable first.
 926		 */
 927		set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
 928		set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
 929
 930		free_reserved_area((void *)begin, (void *)end,
 931				   POISON_FREE_INITMEM, what);
 932	}
 933}
 934
 935/*
 936 * begin/end can be in the direct map or the "high kernel mapping"
 937 * used for the kernel image only.  free_init_pages() will do the
 938 * right thing for either kind of address.
 939 */
 940void free_kernel_image_pages(const char *what, void *begin, void *end)
 941{
 942	unsigned long begin_ul = (unsigned long)begin;
 943	unsigned long end_ul = (unsigned long)end;
 944	unsigned long len_pages = (end_ul - begin_ul) >> PAGE_SHIFT;
 945
 946	free_init_pages(what, begin_ul, end_ul);
 947
 948	/*
 949	 * PTI maps some of the kernel into userspace.  For performance,
 950	 * this includes some kernel areas that do not contain secrets.
 951	 * Those areas might be adjacent to the parts of the kernel image
 952	 * being freed, which may contain secrets.  Remove the "high kernel
 953	 * image mapping" for these freed areas, ensuring they are not even
 954	 * potentially vulnerable to Meltdown regardless of the specific
 955	 * optimizations PTI is currently using.
 956	 *
 957	 * The "noalias" prevents unmapping the direct map alias which is
 958	 * needed to access the freed pages.
 959	 *
 960	 * This is only valid for 64bit kernels. 32bit has only one mapping
 961	 * which can't be treated in this way for obvious reasons.
 962	 */
 963	if (IS_ENABLED(CONFIG_X86_64) && cpu_feature_enabled(X86_FEATURE_PTI))
 964		set_memory_np_noalias(begin_ul, len_pages);
 965}
 966
 967void __ref free_initmem(void)
 968{
 969	e820__reallocate_tables();
 970
 971	mem_encrypt_free_decrypted_mem();
 972
 973	free_kernel_image_pages("unused kernel image (initmem)",
 974				&__init_begin, &__init_end);
 975}
 976
 977#ifdef CONFIG_BLK_DEV_INITRD
 978void __init free_initrd_mem(unsigned long start, unsigned long end)
 979{
 980	/*
 981	 * end could be not aligned, and We can not align that,
 982	 * decompressor could be confused by aligned initrd_end
 983	 * We already reserve the end partial page before in
 984	 *   - i386_start_kernel()
 985	 *   - x86_64_start_kernel()
 986	 *   - relocate_initrd()
 987	 * So here We can do PAGE_ALIGN() safely to get partial page to be freed
 988	 */
 989	free_init_pages("initrd", start, PAGE_ALIGN(end));
 990}
 991#endif
 992
 993/*
 994 * Calculate the precise size of the DMA zone (first 16 MB of RAM),
 995 * and pass it to the MM layer - to help it set zone watermarks more
 996 * accurately.
 997 *
 998 * Done on 64-bit systems only for the time being, although 32-bit systems
 999 * might benefit from this as well.
1000 */
1001void __init memblock_find_dma_reserve(void)
1002{
1003#ifdef CONFIG_X86_64
1004	u64 nr_pages = 0, nr_free_pages = 0;
1005	unsigned long start_pfn, end_pfn;
1006	phys_addr_t start_addr, end_addr;
1007	int i;
1008	u64 u;
1009
1010	/*
1011	 * Iterate over all memory ranges (free and reserved ones alike),
1012	 * to calculate the total number of pages in the first 16 MB of RAM:
1013	 */
1014	nr_pages = 0;
1015	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
1016		start_pfn = min(start_pfn, MAX_DMA_PFN);
1017		end_pfn   = min(end_pfn,   MAX_DMA_PFN);
1018
1019		nr_pages += end_pfn - start_pfn;
1020	}
1021
1022	/*
1023	 * Iterate over free memory ranges to calculate the number of free
1024	 * pages in the DMA zone, while not counting potential partial
1025	 * pages at the beginning or the end of the range:
1026	 */
1027	nr_free_pages = 0;
1028	for_each_free_mem_range(u, NUMA_NO_NODE, MEMBLOCK_NONE, &start_addr, &end_addr, NULL) {
1029		start_pfn = min_t(unsigned long, PFN_UP(start_addr), MAX_DMA_PFN);
1030		end_pfn   = min_t(unsigned long, PFN_DOWN(end_addr), MAX_DMA_PFN);
1031
1032		if (start_pfn < end_pfn)
1033			nr_free_pages += end_pfn - start_pfn;
1034	}
1035
1036	set_dma_reserve(nr_pages - nr_free_pages);
1037#endif
1038}
1039
1040void __init zone_sizes_init(void)
1041{
1042	unsigned long max_zone_pfns[MAX_NR_ZONES];
1043
1044	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
1045
1046#ifdef CONFIG_ZONE_DMA
1047	max_zone_pfns[ZONE_DMA]		= min(MAX_DMA_PFN, max_low_pfn);
1048#endif
1049#ifdef CONFIG_ZONE_DMA32
1050	max_zone_pfns[ZONE_DMA32]	= min(MAX_DMA32_PFN, max_low_pfn);
1051#endif
1052	max_zone_pfns[ZONE_NORMAL]	= max_low_pfn;
1053#ifdef CONFIG_HIGHMEM
1054	max_zone_pfns[ZONE_HIGHMEM]	= max_pfn;
1055#endif
1056
1057	free_area_init(max_zone_pfns);
1058}
1059
1060__visible DEFINE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate) = {
1061	.loaded_mm = &init_mm,
1062	.next_asid = 1,
1063	.cr4 = ~0UL,	/* fail hard if we screw up cr4 shadow initialization */
1064};
1065
1066#ifdef CONFIG_ADDRESS_MASKING
1067DEFINE_PER_CPU(u64, tlbstate_untag_mask);
1068EXPORT_PER_CPU_SYMBOL(tlbstate_untag_mask);
1069#endif
1070
1071void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache)
1072{
1073	/* entry 0 MUST be WB (hardwired to speed up translations) */
1074	BUG_ON(!entry && cache != _PAGE_CACHE_MODE_WB);
1075
1076	__cachemode2pte_tbl[cache] = __cm_idx2pte(entry);
1077	__pte2cachemode_tbl[entry] = cache;
1078}
1079
1080#ifdef CONFIG_SWAP
1081unsigned long arch_max_swapfile_size(void)
1082{
1083	unsigned long pages;
1084
1085	pages = generic_max_swapfile_size();
1086
1087	if (boot_cpu_has_bug(X86_BUG_L1TF) && l1tf_mitigation != L1TF_MITIGATION_OFF) {
1088		/* Limit the swap file size to MAX_PA/2 for L1TF workaround */
1089		unsigned long long l1tf_limit = l1tf_pfn_limit();
1090		/*
1091		 * We encode swap offsets also with 3 bits below those for pfn
1092		 * which makes the usable limit higher.
1093		 */
1094#if CONFIG_PGTABLE_LEVELS > 2
1095		l1tf_limit <<= PAGE_SHIFT - SWP_OFFSET_FIRST_BIT;
1096#endif
1097		pages = min_t(unsigned long long, l1tf_limit, pages);
1098	}
1099	return pages;
1100}
1101#endif