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>
11 #include <asm/set_memory.h>
12 #include <asm/e820/api.h>
15 #include <asm/page_types.h>
16 #include <asm/sections.h>
17 #include <asm/setup.h>
18 #include <asm/tlbflush.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>
27 #include <asm/text-patching.h>
28 #include <asm/memtype.h>
29 #include <asm/paravirt.h>
32 * We need to define the tracepoints somewhere, and tlb.c
33 * is only compiled when SMP=y.
35 #include <trace/events/tlb.h>
37 #include "mm_internal.h"
40 * Tables translating between page_cache_type_t and pte encoding.
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.
48 * Index into __cachemode2pte_tbl[] is the cachemode.
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.
53 static uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = {
54 [_PAGE_CACHE_MODE_WB ] = 0 | 0 ,
55 [_PAGE_CACHE_MODE_WC ] = 0 | _PAGE_PCD,
56 [_PAGE_CACHE_MODE_UC_MINUS] = 0 | _PAGE_PCD,
57 [_PAGE_CACHE_MODE_UC ] = _PAGE_PWT | _PAGE_PCD,
58 [_PAGE_CACHE_MODE_WT ] = 0 | _PAGE_PCD,
59 [_PAGE_CACHE_MODE_WP ] = 0 | _PAGE_PCD,
62 unsigned long cachemode2protval(enum page_cache_mode pcm)
66 return __cachemode2pte_tbl[pcm];
68 EXPORT_SYMBOL(cachemode2protval);
70 static uint8_t __pte2cachemode_tbl[8] = {
71 [__pte2cm_idx( 0 | 0 | 0 )] = _PAGE_CACHE_MODE_WB,
72 [__pte2cm_idx(_PAGE_PWT | 0 | 0 )] = _PAGE_CACHE_MODE_UC_MINUS,
73 [__pte2cm_idx( 0 | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC_MINUS,
74 [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC,
75 [__pte2cm_idx( 0 | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_WB,
76 [__pte2cm_idx(_PAGE_PWT | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS,
77 [__pte2cm_idx(0 | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS,
78 [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC,
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.
90 bool x86_has_pat_wp(void)
92 uint16_t prot = __cachemode2pte_tbl[_PAGE_CACHE_MODE_WP];
94 return __pte2cachemode_tbl[__pte2cm_idx(prot)] == _PAGE_CACHE_MODE_WP;
97 enum page_cache_mode pgprot2cachemode(pgprot_t pgprot)
101 masked = pgprot_val(pgprot) & _PAGE_CACHE_MASK;
102 if (likely(masked == 0))
104 return __pte2cachemode_tbl[__pte2cm_idx(masked)];
107 static unsigned long __initdata pgt_buf_start;
108 static unsigned long __initdata pgt_buf_end;
109 static unsigned long __initdata pgt_buf_top;
111 static unsigned long min_pfn_mapped;
113 static bool __initdata can_use_brk_pgt = true;
116 * Pages returned are already directly mapped.
118 * Changing that is likely to break Xen, see commit:
120 * 279b706 x86,xen: introduce x86_init.mapping.pagetable_reserve
122 * for detailed information.
124 __ref void *alloc_low_pages(unsigned int num)
132 order = get_order((unsigned long)num << PAGE_SHIFT);
133 return (void *)__get_free_pages(GFP_ATOMIC | __GFP_ZERO, order);
136 if ((pgt_buf_end + num) > pgt_buf_top || !can_use_brk_pgt) {
137 unsigned long ret = 0;
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);
145 if (!ret && can_use_brk_pgt)
146 ret = __pa(extend_brk(PAGE_SIZE * num, PAGE_SIZE));
149 panic("alloc_low_pages: can not alloc memory");
151 pfn = ret >> PAGE_SHIFT;
157 for (i = 0; i < num; i++) {
160 adr = __va((pfn + i) << PAGE_SHIFT);
164 return __va(pfn << PAGE_SHIFT);
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.
175 #ifndef CONFIG_X86_5LEVEL
176 #define INIT_PGD_PAGE_TABLES 3
178 #define INIT_PGD_PAGE_TABLES 4
181 #ifndef CONFIG_RANDOMIZE_MEMORY
182 #define INIT_PGD_PAGE_COUNT (2 * INIT_PGD_PAGE_TABLES)
184 #define INIT_PGD_PAGE_COUNT (4 * INIT_PGD_PAGE_TABLES)
187 #define INIT_PGT_BUF_SIZE (INIT_PGD_PAGE_COUNT * PAGE_SIZE)
188 RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
189 void __init early_alloc_pgt_buf(void)
191 unsigned long tables = INIT_PGT_BUF_SIZE;
194 base = __pa(extend_brk(tables, PAGE_SIZE));
196 pgt_buf_start = base >> PAGE_SHIFT;
197 pgt_buf_end = pgt_buf_start;
198 pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
203 early_param_on_off("gbpages", "nogbpages", direct_gbpages, CONFIG_X86_DIRECT_GBPAGES);
208 unsigned page_size_mask;
211 static int page_size_mask;
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.
218 static inline void cr4_set_bits_and_update_boot(unsigned long mask)
220 mmu_cr4_features |= mask;
221 if (trampoline_cr4_features)
222 *trampoline_cr4_features = mmu_cr4_features;
226 static void __init probe_page_size_mask(void)
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.
233 if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled())
234 page_size_mask |= 1 << PG_LEVEL_2M;
238 /* Enable PSE if available */
239 if (boot_cpu_has(X86_FEATURE_PSE))
240 cr4_set_bits_and_update_boot(X86_CR4_PSE);
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;
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;
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;
264 static void setup_pcid(void)
266 if (!IS_ENABLED(CONFIG_X86_64))
269 if (!boot_cpu_has(X86_FEATURE_PCID))
272 if (boot_cpu_has(X86_FEATURE_PGE)) {
274 * This can't be cr4_set_bits_and_update_boot() -- the
275 * trampoline code can't handle CR4.PCIDE and it wouldn't
276 * do any good anyway. Despite the name,
277 * cr4_set_bits_and_update_boot() doesn't actually cause
278 * the bits in question to remain set all the way through
279 * the secondary boot asm.
281 * Instead, we brute-force it and set CR4.PCIDE manually in
284 cr4_set_bits(X86_CR4_PCIDE);
287 * INVPCID's single-context modes (2/3) only work if we set
288 * X86_CR4_PCIDE, *and* we INVPCID support. It's unusable
289 * on systems that have X86_CR4_PCIDE clear, or that have
290 * no INVPCID support at all.
292 if (boot_cpu_has(X86_FEATURE_INVPCID))
293 setup_force_cpu_cap(X86_FEATURE_INVPCID_SINGLE);
296 * flush_tlb_all(), as currently implemented, won't work if
297 * PCID is on but PGE is not. Since that combination
298 * doesn't exist on real hardware, there's no reason to try
299 * to fully support it, but it's polite to avoid corrupting
300 * data if we're on an improperly configured VM.
302 setup_clear_cpu_cap(X86_FEATURE_PCID);
307 #define NR_RANGE_MR 3
308 #else /* CONFIG_X86_64 */
309 #define NR_RANGE_MR 5
312 static int __meminit save_mr(struct map_range *mr, int nr_range,
313 unsigned long start_pfn, unsigned long end_pfn,
314 unsigned long page_size_mask)
316 if (start_pfn < end_pfn) {
317 if (nr_range >= NR_RANGE_MR)
318 panic("run out of range for init_memory_mapping\n");
319 mr[nr_range].start = start_pfn<<PAGE_SHIFT;
320 mr[nr_range].end = end_pfn<<PAGE_SHIFT;
321 mr[nr_range].page_size_mask = page_size_mask;
329 * adjust the page_size_mask for small range to go with
330 * big page size instead small one if nearby are ram too.
332 static void __ref adjust_range_page_size_mask(struct map_range *mr,
337 for (i = 0; i < nr_range; i++) {
338 if ((page_size_mask & (1<<PG_LEVEL_2M)) &&
339 !(mr[i].page_size_mask & (1<<PG_LEVEL_2M))) {
340 unsigned long start = round_down(mr[i].start, PMD_SIZE);
341 unsigned long end = round_up(mr[i].end, PMD_SIZE);
344 if ((end >> PAGE_SHIFT) > max_low_pfn)
348 if (memblock_is_region_memory(start, end - start))
349 mr[i].page_size_mask |= 1<<PG_LEVEL_2M;
351 if ((page_size_mask & (1<<PG_LEVEL_1G)) &&
352 !(mr[i].page_size_mask & (1<<PG_LEVEL_1G))) {
353 unsigned long start = round_down(mr[i].start, PUD_SIZE);
354 unsigned long end = round_up(mr[i].end, PUD_SIZE);
356 if (memblock_is_region_memory(start, end - start))
357 mr[i].page_size_mask |= 1<<PG_LEVEL_1G;
362 static const char *page_size_string(struct map_range *mr)
364 static const char str_1g[] = "1G";
365 static const char str_2m[] = "2M";
366 static const char str_4m[] = "4M";
367 static const char str_4k[] = "4k";
369 if (mr->page_size_mask & (1<<PG_LEVEL_1G))
372 * 32-bit without PAE has a 4M large page size.
373 * PG_LEVEL_2M is misnamed, but we can at least
374 * print out the right size in the string.
376 if (IS_ENABLED(CONFIG_X86_32) &&
377 !IS_ENABLED(CONFIG_X86_PAE) &&
378 mr->page_size_mask & (1<<PG_LEVEL_2M))
381 if (mr->page_size_mask & (1<<PG_LEVEL_2M))
387 static int __meminit split_mem_range(struct map_range *mr, int nr_range,
391 unsigned long start_pfn, end_pfn, limit_pfn;
395 limit_pfn = PFN_DOWN(end);
397 /* head if not big page alignment ? */
398 pfn = start_pfn = PFN_DOWN(start);
401 * Don't use a large page for the first 2/4MB of memory
402 * because there are often fixed size MTRRs in there
403 * and overlapping MTRRs into large pages can cause
407 end_pfn = PFN_DOWN(PMD_SIZE);
409 end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
410 #else /* CONFIG_X86_64 */
411 end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
413 if (end_pfn > limit_pfn)
415 if (start_pfn < end_pfn) {
416 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
420 /* big page (2M) range */
421 start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
423 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
424 #else /* CONFIG_X86_64 */
425 end_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE));
426 if (end_pfn > round_down(limit_pfn, PFN_DOWN(PMD_SIZE)))
427 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
430 if (start_pfn < end_pfn) {
431 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
432 page_size_mask & (1<<PG_LEVEL_2M));
437 /* big page (1G) range */
438 start_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE));
439 end_pfn = round_down(limit_pfn, PFN_DOWN(PUD_SIZE));
440 if (start_pfn < end_pfn) {
441 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
443 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
447 /* tail is not big page (1G) alignment */
448 start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
449 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
450 if (start_pfn < end_pfn) {
451 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
452 page_size_mask & (1<<PG_LEVEL_2M));
457 /* tail is not big page (2M) alignment */
460 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
463 adjust_range_page_size_mask(mr, nr_range);
465 /* try to merge same page size and continuous */
466 for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
467 unsigned long old_start;
468 if (mr[i].end != mr[i+1].start ||
469 mr[i].page_size_mask != mr[i+1].page_size_mask)
472 old_start = mr[i].start;
473 memmove(&mr[i], &mr[i+1],
474 (nr_range - 1 - i) * sizeof(struct map_range));
475 mr[i--].start = old_start;
479 for (i = 0; i < nr_range; i++)
480 pr_debug(" [mem %#010lx-%#010lx] page %s\n",
481 mr[i].start, mr[i].end - 1,
482 page_size_string(&mr[i]));
487 struct range pfn_mapped[E820_MAX_ENTRIES];
490 static void add_pfn_range_mapped(unsigned long start_pfn, unsigned long end_pfn)
492 nr_pfn_mapped = add_range_with_merge(pfn_mapped, E820_MAX_ENTRIES,
493 nr_pfn_mapped, start_pfn, end_pfn);
494 nr_pfn_mapped = clean_sort_range(pfn_mapped, E820_MAX_ENTRIES);
496 max_pfn_mapped = max(max_pfn_mapped, end_pfn);
498 if (start_pfn < (1UL<<(32-PAGE_SHIFT)))
499 max_low_pfn_mapped = max(max_low_pfn_mapped,
500 min(end_pfn, 1UL<<(32-PAGE_SHIFT)));
503 bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn)
507 for (i = 0; i < nr_pfn_mapped; i++)
508 if ((start_pfn >= pfn_mapped[i].start) &&
509 (end_pfn <= pfn_mapped[i].end))
516 * Setup the direct mapping of the physical memory at PAGE_OFFSET.
517 * This runs before bootmem is initialized and gets pages directly from
518 * the physical memory. To access them they are temporarily mapped.
520 unsigned long __ref init_memory_mapping(unsigned long start,
521 unsigned long end, pgprot_t prot)
523 struct map_range mr[NR_RANGE_MR];
524 unsigned long ret = 0;
527 pr_debug("init_memory_mapping: [mem %#010lx-%#010lx]\n",
530 memset(mr, 0, sizeof(mr));
531 nr_range = split_mem_range(mr, 0, start, end);
533 for (i = 0; i < nr_range; i++)
534 ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
535 mr[i].page_size_mask,
538 add_pfn_range_mapped(start >> PAGE_SHIFT, ret >> PAGE_SHIFT);
540 return ret >> PAGE_SHIFT;
544 * We need to iterate through the E820 memory map and create direct mappings
545 * for only E820_TYPE_RAM and E820_KERN_RESERVED regions. We cannot simply
546 * create direct mappings for all pfns from [0 to max_low_pfn) and
547 * [4GB to max_pfn) because of possible memory holes in high addresses
548 * that cannot be marked as UC by fixed/variable range MTRRs.
549 * Depending on the alignment of E820 ranges, this may possibly result
550 * in using smaller size (i.e. 4K instead of 2M or 1G) page tables.
552 * init_mem_mapping() calls init_range_memory_mapping() with big range.
553 * That range would have hole in the middle or ends, and only ram parts
554 * will be mapped in init_range_memory_mapping().
556 static unsigned long __init init_range_memory_mapping(
557 unsigned long r_start,
560 unsigned long start_pfn, end_pfn;
561 unsigned long mapped_ram_size = 0;
564 for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
565 u64 start = clamp_val(PFN_PHYS(start_pfn), r_start, r_end);
566 u64 end = clamp_val(PFN_PHYS(end_pfn), r_start, r_end);
571 * if it is overlapping with brk pgt, we need to
572 * alloc pgt buf from memblock instead.
574 can_use_brk_pgt = max(start, (u64)pgt_buf_end<<PAGE_SHIFT) >=
575 min(end, (u64)pgt_buf_top<<PAGE_SHIFT);
576 init_memory_mapping(start, end, PAGE_KERNEL);
577 mapped_ram_size += end - start;
578 can_use_brk_pgt = true;
581 return mapped_ram_size;
584 static unsigned long __init get_new_step_size(unsigned long step_size)
587 * Initial mapped size is PMD_SIZE (2M).
588 * We can not set step_size to be PUD_SIZE (1G) yet.
589 * In worse case, when we cross the 1G boundary, and
590 * PG_LEVEL_2M is not set, we will need 1+1+512 pages (2M + 8k)
591 * to map 1G range with PTE. Hence we use one less than the
592 * difference of page table level shifts.
594 * Don't need to worry about overflow in the top-down case, on 32bit,
595 * when step_size is 0, round_down() returns 0 for start, and that
596 * turns it into 0x100000000ULL.
597 * In the bottom-up case, round_up(x, 0) returns 0 though too, which
598 * needs to be taken into consideration by the code below.
600 return step_size << (PMD_SHIFT - PAGE_SHIFT - 1);
604 * memory_map_top_down - Map [map_start, map_end) top down
605 * @map_start: start address of the target memory range
606 * @map_end: end address of the target memory range
608 * This function will setup direct mapping for memory range
609 * [map_start, map_end) in top-down. That said, the page tables
610 * will be allocated at the end of the memory, and we map the
611 * memory in top-down.
613 static void __init memory_map_top_down(unsigned long map_start,
614 unsigned long map_end)
616 unsigned long real_end, last_start;
617 unsigned long step_size;
619 unsigned long mapped_ram_size = 0;
622 * Systems that have many reserved areas near top of the memory,
623 * e.g. QEMU with less than 1G RAM and EFI enabled, or Xen, will
624 * require lots of 4K mappings which may exhaust pgt_buf.
625 * Start with top-most PMD_SIZE range aligned at PMD_SIZE to ensure
626 * there is enough mapped memory that can be allocated from
629 addr = memblock_phys_alloc_range(PMD_SIZE, PMD_SIZE, map_start,
631 memblock_phys_free(addr, PMD_SIZE);
632 real_end = addr + PMD_SIZE;
634 /* step_size need to be small so pgt_buf from BRK could cover it */
635 step_size = PMD_SIZE;
636 max_pfn_mapped = 0; /* will get exact value next */
637 min_pfn_mapped = real_end >> PAGE_SHIFT;
638 last_start = real_end;
641 * We start from the top (end of memory) and go to the bottom.
642 * The memblock_find_in_range() gets us a block of RAM from the
643 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
646 while (last_start > map_start) {
649 if (last_start > step_size) {
650 start = round_down(last_start - 1, step_size);
651 if (start < map_start)
655 mapped_ram_size += init_range_memory_mapping(start,
658 min_pfn_mapped = last_start >> PAGE_SHIFT;
659 if (mapped_ram_size >= step_size)
660 step_size = get_new_step_size(step_size);
663 if (real_end < map_end)
664 init_range_memory_mapping(real_end, map_end);
668 * memory_map_bottom_up - Map [map_start, map_end) bottom up
669 * @map_start: start address of the target memory range
670 * @map_end: end address of the target memory range
672 * This function will setup direct mapping for memory range
673 * [map_start, map_end) in bottom-up. Since we have limited the
674 * bottom-up allocation above the kernel, the page tables will
675 * be allocated just above the kernel and we map the memory
676 * in [map_start, map_end) in bottom-up.
678 static void __init memory_map_bottom_up(unsigned long map_start,
679 unsigned long map_end)
681 unsigned long next, start;
682 unsigned long mapped_ram_size = 0;
683 /* step_size need to be small so pgt_buf from BRK could cover it */
684 unsigned long step_size = PMD_SIZE;
687 min_pfn_mapped = start >> PAGE_SHIFT;
690 * We start from the bottom (@map_start) and go to the top (@map_end).
691 * The memblock_find_in_range() gets us a block of RAM from the
692 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
695 while (start < map_end) {
696 if (step_size && map_end - start > step_size) {
697 next = round_up(start + 1, step_size);
704 mapped_ram_size += init_range_memory_mapping(start, next);
707 if (mapped_ram_size >= step_size)
708 step_size = get_new_step_size(step_size);
713 * The real mode trampoline, which is required for bootstrapping CPUs
714 * occupies only a small area under the low 1MB. See reserve_real_mode()
717 * If KASLR is disabled the first PGD entry of the direct mapping is copied
718 * to map the real mode trampoline.
720 * If KASLR is enabled, copy only the PUD which covers the low 1MB
721 * area. This limits the randomization granularity to 1GB for both 4-level
722 * and 5-level paging.
724 static void __init init_trampoline(void)
728 * The code below will alias kernel page-tables in the user-range of the
729 * address space, including the Global bit. So global TLB entries will
730 * be created when using the trampoline page-table.
732 if (!kaslr_memory_enabled())
733 trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)];
735 init_trampoline_kaslr();
739 void __init init_mem_mapping(void)
743 pti_check_boottime_disable();
744 probe_page_size_mask();
748 end = max_pfn << PAGE_SHIFT;
750 end = max_low_pfn << PAGE_SHIFT;
753 /* the ISA range is always mapped regardless of memory holes */
754 init_memory_mapping(0, ISA_END_ADDRESS, PAGE_KERNEL);
756 /* Init the trampoline, possibly with KASLR memory offset */
760 * If the allocation is in bottom-up direction, we setup direct mapping
761 * in bottom-up, otherwise we setup direct mapping in top-down.
763 if (memblock_bottom_up()) {
764 unsigned long kernel_end = __pa_symbol(_end);
767 * we need two separate calls here. This is because we want to
768 * allocate page tables above the kernel. So we first map
769 * [kernel_end, end) to make memory above the kernel be mapped
770 * as soon as possible. And then use page tables allocated above
771 * the kernel to map [ISA_END_ADDRESS, kernel_end).
773 memory_map_bottom_up(kernel_end, end);
774 memory_map_bottom_up(ISA_END_ADDRESS, kernel_end);
776 memory_map_top_down(ISA_END_ADDRESS, end);
780 if (max_pfn > max_low_pfn) {
781 /* can we preserve max_low_pfn ?*/
782 max_low_pfn = max_pfn;
785 early_ioremap_page_table_range_init();
788 load_cr3(swapper_pg_dir);
791 x86_init.hyper.init_mem_mapping();
793 early_memtest(0, max_pfn_mapped << PAGE_SHIFT);
797 * Initialize an mm_struct to be used during poking and a pointer to be used
800 void __init poking_init(void)
805 poking_mm = mm_alloc();
808 /* Xen PV guests need the PGD to be pinned. */
809 paravirt_enter_mmap(poking_mm);
812 * Randomize the poking address, but make sure that the following page
813 * will be mapped at the same PMD. We need 2 pages, so find space for 3,
814 * and adjust the address if the PMD ends after the first one.
816 poking_addr = TASK_UNMAPPED_BASE;
817 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
818 poking_addr += (kaslr_get_random_long("Poking") & PAGE_MASK) %
819 (TASK_SIZE - TASK_UNMAPPED_BASE - 3 * PAGE_SIZE);
821 if (((poking_addr + PAGE_SIZE) & ~PMD_MASK) == 0)
822 poking_addr += PAGE_SIZE;
825 * We need to trigger the allocation of the page-tables that will be
826 * needed for poking now. Later, poking may be performed in an atomic
827 * section, which might cause allocation to fail.
829 ptep = get_locked_pte(poking_mm, poking_addr, &ptl);
831 pte_unmap_unlock(ptep, ptl);
835 * devmem_is_allowed() checks to see if /dev/mem access to a certain address
836 * is valid. The argument is a physical page number.
838 * On x86, access has to be given to the first megabyte of RAM because that
839 * area traditionally contains BIOS code and data regions used by X, dosemu,
840 * and similar apps. Since they map the entire memory range, the whole range
841 * must be allowed (for mapping), but any areas that would otherwise be
842 * disallowed are flagged as being "zero filled" instead of rejected.
843 * Access has to be given to non-kernel-ram areas as well, these contain the
844 * PCI mmio resources as well as potential bios/acpi data regions.
846 int devmem_is_allowed(unsigned long pagenr)
848 if (region_intersects(PFN_PHYS(pagenr), PAGE_SIZE,
849 IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE)
850 != REGION_DISJOINT) {
852 * For disallowed memory regions in the low 1MB range,
853 * request that the page be shown as all zeros.
862 * This must follow RAM test, since System RAM is considered a
863 * restricted resource under CONFIG_STRICT_DEVMEM.
865 if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) {
866 /* Low 1MB bypasses iomem restrictions. */
876 void free_init_pages(const char *what, unsigned long begin, unsigned long end)
878 unsigned long begin_aligned, end_aligned;
880 /* Make sure boundaries are page aligned */
881 begin_aligned = PAGE_ALIGN(begin);
882 end_aligned = end & PAGE_MASK;
884 if (WARN_ON(begin_aligned != begin || end_aligned != end)) {
885 begin = begin_aligned;
893 * If debugging page accesses then do not free this memory but
894 * mark them not present - any buggy init-section access will
895 * create a kernel page fault:
897 if (debug_pagealloc_enabled()) {
898 pr_info("debug: unmapping init [mem %#010lx-%#010lx]\n",
901 * Inform kmemleak about the hole in the memory since the
902 * corresponding pages will be unmapped.
904 kmemleak_free_part((void *)begin, end - begin);
905 set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
908 * We just marked the kernel text read only above, now that
909 * we are going to free part of that, we need to make that
910 * writeable and non-executable first.
912 set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
913 set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
915 free_reserved_area((void *)begin, (void *)end,
916 POISON_FREE_INITMEM, what);
921 * begin/end can be in the direct map or the "high kernel mapping"
922 * used for the kernel image only. free_init_pages() will do the
923 * right thing for either kind of address.
925 void free_kernel_image_pages(const char *what, void *begin, void *end)
927 unsigned long begin_ul = (unsigned long)begin;
928 unsigned long end_ul = (unsigned long)end;
929 unsigned long len_pages = (end_ul - begin_ul) >> PAGE_SHIFT;
931 free_init_pages(what, begin_ul, end_ul);
934 * PTI maps some of the kernel into userspace. For performance,
935 * this includes some kernel areas that do not contain secrets.
936 * Those areas might be adjacent to the parts of the kernel image
937 * being freed, which may contain secrets. Remove the "high kernel
938 * image mapping" for these freed areas, ensuring they are not even
939 * potentially vulnerable to Meltdown regardless of the specific
940 * optimizations PTI is currently using.
942 * The "noalias" prevents unmapping the direct map alias which is
943 * needed to access the freed pages.
945 * This is only valid for 64bit kernels. 32bit has only one mapping
946 * which can't be treated in this way for obvious reasons.
948 if (IS_ENABLED(CONFIG_X86_64) && cpu_feature_enabled(X86_FEATURE_PTI))
949 set_memory_np_noalias(begin_ul, len_pages);
952 void __ref free_initmem(void)
954 e820__reallocate_tables();
956 mem_encrypt_free_decrypted_mem();
958 free_kernel_image_pages("unused kernel image (initmem)",
959 &__init_begin, &__init_end);
962 #ifdef CONFIG_BLK_DEV_INITRD
963 void __init free_initrd_mem(unsigned long start, unsigned long end)
966 * end could be not aligned, and We can not align that,
967 * decompressor could be confused by aligned initrd_end
968 * We already reserve the end partial page before in
969 * - i386_start_kernel()
970 * - x86_64_start_kernel()
971 * - relocate_initrd()
972 * So here We can do PAGE_ALIGN() safely to get partial page to be freed
974 free_init_pages("initrd", start, PAGE_ALIGN(end));
979 * Calculate the precise size of the DMA zone (first 16 MB of RAM),
980 * and pass it to the MM layer - to help it set zone watermarks more
983 * Done on 64-bit systems only for the time being, although 32-bit systems
984 * might benefit from this as well.
986 void __init memblock_find_dma_reserve(void)
989 u64 nr_pages = 0, nr_free_pages = 0;
990 unsigned long start_pfn, end_pfn;
991 phys_addr_t start_addr, end_addr;
996 * Iterate over all memory ranges (free and reserved ones alike),
997 * to calculate the total number of pages in the first 16 MB of RAM:
1000 for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
1001 start_pfn = min(start_pfn, MAX_DMA_PFN);
1002 end_pfn = min(end_pfn, MAX_DMA_PFN);
1004 nr_pages += end_pfn - start_pfn;
1008 * Iterate over free memory ranges to calculate the number of free
1009 * pages in the DMA zone, while not counting potential partial
1010 * pages at the beginning or the end of the range:
1013 for_each_free_mem_range(u, NUMA_NO_NODE, MEMBLOCK_NONE, &start_addr, &end_addr, NULL) {
1014 start_pfn = min_t(unsigned long, PFN_UP(start_addr), MAX_DMA_PFN);
1015 end_pfn = min_t(unsigned long, PFN_DOWN(end_addr), MAX_DMA_PFN);
1017 if (start_pfn < end_pfn)
1018 nr_free_pages += end_pfn - start_pfn;
1021 set_dma_reserve(nr_pages - nr_free_pages);
1025 void __init zone_sizes_init(void)
1027 unsigned long max_zone_pfns[MAX_NR_ZONES];
1029 memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
1031 #ifdef CONFIG_ZONE_DMA
1032 max_zone_pfns[ZONE_DMA] = min(MAX_DMA_PFN, max_low_pfn);
1034 #ifdef CONFIG_ZONE_DMA32
1035 max_zone_pfns[ZONE_DMA32] = min(MAX_DMA32_PFN, max_low_pfn);
1037 max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
1038 #ifdef CONFIG_HIGHMEM
1039 max_zone_pfns[ZONE_HIGHMEM] = max_pfn;
1042 free_area_init(max_zone_pfns);
1045 __visible DEFINE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate) = {
1046 .loaded_mm = &init_mm,
1048 .cr4 = ~0UL, /* fail hard if we screw up cr4 shadow initialization */
1051 #ifdef CONFIG_ADDRESS_MASKING
1052 DEFINE_PER_CPU(u64, tlbstate_untag_mask);
1053 EXPORT_PER_CPU_SYMBOL(tlbstate_untag_mask);
1056 void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache)
1058 /* entry 0 MUST be WB (hardwired to speed up translations) */
1059 BUG_ON(!entry && cache != _PAGE_CACHE_MODE_WB);
1061 __cachemode2pte_tbl[cache] = __cm_idx2pte(entry);
1062 __pte2cachemode_tbl[entry] = cache;
1066 unsigned long arch_max_swapfile_size(void)
1068 unsigned long pages;
1070 pages = generic_max_swapfile_size();
1072 if (boot_cpu_has_bug(X86_BUG_L1TF) && l1tf_mitigation != L1TF_MITIGATION_OFF) {
1073 /* Limit the swap file size to MAX_PA/2 for L1TF workaround */
1074 unsigned long long l1tf_limit = l1tf_pfn_limit();
1076 * We encode swap offsets also with 3 bits below those for pfn
1077 * which makes the usable limit higher.
1079 #if CONFIG_PGTABLE_LEVELS > 2
1080 l1tf_limit <<= PAGE_SHIFT - SWP_OFFSET_FIRST_BIT;
1082 pages = min_t(unsigned long long, l1tf_limit, pages);