linux/arch/x86/mm/init_32.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *
   4 *  Copyright (C) 1995  Linus Torvalds
   5 *
   6 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   7 */
   8
   9#include <linux/signal.h>
  10#include <linux/sched.h>
  11#include <linux/kernel.h>
  12#include <linux/errno.h>
  13#include <linux/string.h>
  14#include <linux/types.h>
  15#include <linux/ptrace.h>
  16#include <linux/mman.h>
  17#include <linux/mm.h>
  18#include <linux/hugetlb.h>
  19#include <linux/swap.h>
  20#include <linux/smp.h>
  21#include <linux/init.h>
  22#include <linux/highmem.h>
  23#include <linux/pagemap.h>
  24#include <linux/pci.h>
  25#include <linux/pfn.h>
  26#include <linux/poison.h>
  27#include <linux/memblock.h>
  28#include <linux/proc_fs.h>
  29#include <linux/memory_hotplug.h>
  30#include <linux/initrd.h>
  31#include <linux/cpumask.h>
  32#include <linux/gfp.h>
  33
  34#include <asm/asm.h>
  35#include <asm/bios_ebda.h>
  36#include <asm/processor.h>
  37#include <linux/uaccess.h>
  38#include <asm/dma.h>
  39#include <asm/fixmap.h>
  40#include <asm/e820/api.h>
  41#include <asm/apic.h>
  42#include <asm/bugs.h>
  43#include <asm/tlb.h>
  44#include <asm/tlbflush.h>
  45#include <asm/olpc_ofw.h>
  46#include <asm/pgalloc.h>
  47#include <asm/sections.h>
  48#include <asm/paravirt.h>
  49#include <asm/setup.h>
  50#include <asm/set_memory.h>
  51#include <asm/page_types.h>
  52#include <asm/cpu_entry_area.h>
  53#include <asm/init.h>
  54#include <asm/pgtable_areas.h>
  55#include <asm/numa.h>
  56
  57#include "mm_internal.h"
  58
  59unsigned long highstart_pfn, highend_pfn;
  60
  61bool __read_mostly __vmalloc_start_set = false;
  62
  63/*
  64 * Creates a middle page table and puts a pointer to it in the
  65 * given global directory entry. This only returns the gd entry
  66 * in non-PAE compilation mode, since the middle layer is folded.
  67 */
  68static pmd_t * __init one_md_table_init(pgd_t *pgd)
  69{
  70        p4d_t *p4d;
  71        pud_t *pud;
  72        pmd_t *pmd_table;
  73
  74#ifdef CONFIG_X86_PAE
  75        if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
  76                pmd_table = (pmd_t *)alloc_low_page();
  77                paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
  78                set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
  79                p4d = p4d_offset(pgd, 0);
  80                pud = pud_offset(p4d, 0);
  81                BUG_ON(pmd_table != pmd_offset(pud, 0));
  82
  83                return pmd_table;
  84        }
  85#endif
  86        p4d = p4d_offset(pgd, 0);
  87        pud = pud_offset(p4d, 0);
  88        pmd_table = pmd_offset(pud, 0);
  89
  90        return pmd_table;
  91}
  92
  93/*
  94 * Create a page table and place a pointer to it in a middle page
  95 * directory entry:
  96 */
  97static pte_t * __init one_page_table_init(pmd_t *pmd)
  98{
  99        if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
 100                pte_t *page_table = (pte_t *)alloc_low_page();
 101
 102                paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
 103                set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
 104                BUG_ON(page_table != pte_offset_kernel(pmd, 0));
 105        }
 106
 107        return pte_offset_kernel(pmd, 0);
 108}
 109
 110pmd_t * __init populate_extra_pmd(unsigned long vaddr)
 111{
 112        int pgd_idx = pgd_index(vaddr);
 113        int pmd_idx = pmd_index(vaddr);
 114
 115        return one_md_table_init(swapper_pg_dir + pgd_idx) + pmd_idx;
 116}
 117
 118pte_t * __init populate_extra_pte(unsigned long vaddr)
 119{
 120        int pte_idx = pte_index(vaddr);
 121        pmd_t *pmd;
 122
 123        pmd = populate_extra_pmd(vaddr);
 124        return one_page_table_init(pmd) + pte_idx;
 125}
 126
 127static unsigned long __init
 128page_table_range_init_count(unsigned long start, unsigned long end)
 129{
 130        unsigned long count = 0;
 131#ifdef CONFIG_HIGHMEM
 132        int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
 133        int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
 134        int pgd_idx, pmd_idx;
 135        unsigned long vaddr;
 136
 137        if (pmd_idx_kmap_begin == pmd_idx_kmap_end)
 138                return 0;
 139
 140        vaddr = start;
 141        pgd_idx = pgd_index(vaddr);
 142        pmd_idx = pmd_index(vaddr);
 143
 144        for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd_idx++) {
 145                for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
 146                                                        pmd_idx++) {
 147                        if ((vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin &&
 148                            (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end)
 149                                count++;
 150                        vaddr += PMD_SIZE;
 151                }
 152                pmd_idx = 0;
 153        }
 154#endif
 155        return count;
 156}
 157
 158static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
 159                                           unsigned long vaddr, pte_t *lastpte,
 160                                           void **adr)
 161{
 162#ifdef CONFIG_HIGHMEM
 163        /*
 164         * Something (early fixmap) may already have put a pte
 165         * page here, which causes the page table allocation
 166         * to become nonlinear. Attempt to fix it, and if it
 167         * is still nonlinear then we have to bug.
 168         */
 169        int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
 170        int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
 171
 172        if (pmd_idx_kmap_begin != pmd_idx_kmap_end
 173            && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
 174            && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end) {
 175                pte_t *newpte;
 176                int i;
 177
 178                BUG_ON(after_bootmem);
 179                newpte = *adr;
 180                for (i = 0; i < PTRS_PER_PTE; i++)
 181                        set_pte(newpte + i, pte[i]);
 182                *adr = (void *)(((unsigned long)(*adr)) + PAGE_SIZE);
 183
 184                paravirt_alloc_pte(&init_mm, __pa(newpte) >> PAGE_SHIFT);
 185                set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
 186                BUG_ON(newpte != pte_offset_kernel(pmd, 0));
 187                __flush_tlb_all();
 188
 189                paravirt_release_pte(__pa(pte) >> PAGE_SHIFT);
 190                pte = newpte;
 191        }
 192        BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
 193               && vaddr > fix_to_virt(FIX_KMAP_END)
 194               && lastpte && lastpte + PTRS_PER_PTE != pte);
 195#endif
 196        return pte;
 197}
 198
 199/*
 200 * This function initializes a certain range of kernel virtual memory
 201 * with new bootmem page tables, everywhere page tables are missing in
 202 * the given range.
 203 *
 204 * NOTE: The pagetables are allocated contiguous on the physical space
 205 * so we can cache the place of the first one and move around without
 206 * checking the pgd every time.
 207 */
 208static void __init
 209page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
 210{
 211        int pgd_idx, pmd_idx;
 212        unsigned long vaddr;
 213        pgd_t *pgd;
 214        pmd_t *pmd;
 215        pte_t *pte = NULL;
 216        unsigned long count = page_table_range_init_count(start, end);
 217        void *adr = NULL;
 218
 219        if (count)
 220                adr = alloc_low_pages(count);
 221
 222        vaddr = start;
 223        pgd_idx = pgd_index(vaddr);
 224        pmd_idx = pmd_index(vaddr);
 225        pgd = pgd_base + pgd_idx;
 226
 227        for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
 228                pmd = one_md_table_init(pgd);
 229                pmd = pmd + pmd_index(vaddr);
 230                for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
 231                                                        pmd++, pmd_idx++) {
 232                        pte = page_table_kmap_check(one_page_table_init(pmd),
 233                                                    pmd, vaddr, pte, &adr);
 234
 235                        vaddr += PMD_SIZE;
 236                }
 237                pmd_idx = 0;
 238        }
 239}
 240
 241/*
 242 * The <linux/kallsyms.h> already defines is_kernel_text,
 243 * using '__' prefix not to get in conflict.
 244 */
 245static inline int __is_kernel_text(unsigned long addr)
 246{
 247        if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
 248                return 1;
 249        return 0;
 250}
 251
 252/*
 253 * This maps the physical memory to kernel virtual address space, a total
 254 * of max_low_pfn pages, by creating page tables starting from address
 255 * PAGE_OFFSET:
 256 */
 257unsigned long __init
 258kernel_physical_mapping_init(unsigned long start,
 259                             unsigned long end,
 260                             unsigned long page_size_mask,
 261                             pgprot_t prot)
 262{
 263        int use_pse = page_size_mask == (1<<PG_LEVEL_2M);
 264        unsigned long last_map_addr = end;
 265        unsigned long start_pfn, end_pfn;
 266        pgd_t *pgd_base = swapper_pg_dir;
 267        int pgd_idx, pmd_idx, pte_ofs;
 268        unsigned long pfn;
 269        pgd_t *pgd;
 270        pmd_t *pmd;
 271        pte_t *pte;
 272        unsigned pages_2m, pages_4k;
 273        int mapping_iter;
 274
 275        start_pfn = start >> PAGE_SHIFT;
 276        end_pfn = end >> PAGE_SHIFT;
 277
 278        /*
 279         * First iteration will setup identity mapping using large/small pages
 280         * based on use_pse, with other attributes same as set by
 281         * the early code in head_32.S
 282         *
 283         * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
 284         * as desired for the kernel identity mapping.
 285         *
 286         * This two pass mechanism conforms to the TLB app note which says:
 287         *
 288         *     "Software should not write to a paging-structure entry in a way
 289         *      that would change, for any linear address, both the page size
 290         *      and either the page frame or attributes."
 291         */
 292        mapping_iter = 1;
 293
 294        if (!boot_cpu_has(X86_FEATURE_PSE))
 295                use_pse = 0;
 296
 297repeat:
 298        pages_2m = pages_4k = 0;
 299        pfn = start_pfn;
 300        pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
 301        pgd = pgd_base + pgd_idx;
 302        for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
 303                pmd = one_md_table_init(pgd);
 304
 305                if (pfn >= end_pfn)
 306                        continue;
 307#ifdef CONFIG_X86_PAE
 308                pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
 309                pmd += pmd_idx;
 310#else
 311                pmd_idx = 0;
 312#endif
 313                for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
 314                     pmd++, pmd_idx++) {
 315                        unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
 316
 317                        /*
 318                         * Map with big pages if possible, otherwise
 319                         * create normal page tables:
 320                         */
 321                        if (use_pse) {
 322                                unsigned int addr2;
 323                                pgprot_t prot = PAGE_KERNEL_LARGE;
 324                                /*
 325                                 * first pass will use the same initial
 326                                 * identity mapping attribute + _PAGE_PSE.
 327                                 */
 328                                pgprot_t init_prot =
 329                                        __pgprot(PTE_IDENT_ATTR |
 330                                                 _PAGE_PSE);
 331
 332                                pfn &= PMD_MASK >> PAGE_SHIFT;
 333                                addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
 334                                        PAGE_OFFSET + PAGE_SIZE-1;
 335
 336                                if (__is_kernel_text(addr) ||
 337                                    __is_kernel_text(addr2))
 338                                        prot = PAGE_KERNEL_LARGE_EXEC;
 339
 340                                pages_2m++;
 341                                if (mapping_iter == 1)
 342                                        set_pmd(pmd, pfn_pmd(pfn, init_prot));
 343                                else
 344                                        set_pmd(pmd, pfn_pmd(pfn, prot));
 345
 346                                pfn += PTRS_PER_PTE;
 347                                continue;
 348                        }
 349                        pte = one_page_table_init(pmd);
 350
 351                        pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
 352                        pte += pte_ofs;
 353                        for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
 354                             pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
 355                                pgprot_t prot = PAGE_KERNEL;
 356                                /*
 357                                 * first pass will use the same initial
 358                                 * identity mapping attribute.
 359                                 */
 360                                pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);
 361
 362                                if (__is_kernel_text(addr))
 363                                        prot = PAGE_KERNEL_EXEC;
 364
 365                                pages_4k++;
 366                                if (mapping_iter == 1) {
 367                                        set_pte(pte, pfn_pte(pfn, init_prot));
 368                                        last_map_addr = (pfn << PAGE_SHIFT) + PAGE_SIZE;
 369                                } else
 370                                        set_pte(pte, pfn_pte(pfn, prot));
 371                        }
 372                }
 373        }
 374        if (mapping_iter == 1) {
 375                /*
 376                 * update direct mapping page count only in the first
 377                 * iteration.
 378                 */
 379                update_page_count(PG_LEVEL_2M, pages_2m);
 380                update_page_count(PG_LEVEL_4K, pages_4k);
 381
 382                /*
 383                 * local global flush tlb, which will flush the previous
 384                 * mappings present in both small and large page TLB's.
 385                 */
 386                __flush_tlb_all();
 387
 388                /*
 389                 * Second iteration will set the actual desired PTE attributes.
 390                 */
 391                mapping_iter = 2;
 392                goto repeat;
 393        }
 394        return last_map_addr;
 395}
 396
 397#ifdef CONFIG_HIGHMEM
 398static void __init permanent_kmaps_init(pgd_t *pgd_base)
 399{
 400        unsigned long vaddr = PKMAP_BASE;
 401
 402        page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
 403
 404        pkmap_page_table = virt_to_kpte(vaddr);
 405}
 406
 407void __init add_highpages_with_active_regions(int nid,
 408                         unsigned long start_pfn, unsigned long end_pfn)
 409{
 410        phys_addr_t start, end;
 411        u64 i;
 412
 413        for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
 414                unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
 415                                            start_pfn, end_pfn);
 416                unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
 417                                              start_pfn, end_pfn);
 418                for ( ; pfn < e_pfn; pfn++)
 419                        if (pfn_valid(pfn))
 420                                free_highmem_page(pfn_to_page(pfn));
 421        }
 422}
 423#else
 424static inline void permanent_kmaps_init(pgd_t *pgd_base)
 425{
 426}
 427#endif /* CONFIG_HIGHMEM */
 428
 429void __init sync_initial_page_table(void)
 430{
 431        clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
 432                        swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
 433                        KERNEL_PGD_PTRS);
 434
 435        /*
 436         * sync back low identity map too.  It is used for example
 437         * in the 32-bit EFI stub.
 438         */
 439        clone_pgd_range(initial_page_table,
 440                        swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
 441                        min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
 442}
 443
 444void __init native_pagetable_init(void)
 445{
 446        unsigned long pfn, va;
 447        pgd_t *pgd, *base = swapper_pg_dir;
 448        p4d_t *p4d;
 449        pud_t *pud;
 450        pmd_t *pmd;
 451        pte_t *pte;
 452
 453        /*
 454         * Remove any mappings which extend past the end of physical
 455         * memory from the boot time page table.
 456         * In virtual address space, we should have at least two pages
 457         * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
 458         * definition. And max_low_pfn is set to VMALLOC_END physical
 459         * address. If initial memory mapping is doing right job, we
 460         * should have pte used near max_low_pfn or one pmd is not present.
 461         */
 462        for (pfn = max_low_pfn; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
 463                va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
 464                pgd = base + pgd_index(va);
 465                if (!pgd_present(*pgd))
 466                        break;
 467
 468                p4d = p4d_offset(pgd, va);
 469                pud = pud_offset(p4d, va);
 470                pmd = pmd_offset(pud, va);
 471                if (!pmd_present(*pmd))
 472                        break;
 473
 474                /* should not be large page here */
 475                if (pmd_large(*pmd)) {
 476                        pr_warn("try to clear pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx, but pmd is big page and is not using pte !\n",
 477                                pfn, pmd, __pa(pmd));
 478                        BUG_ON(1);
 479                }
 480
 481                pte = pte_offset_kernel(pmd, va);
 482                if (!pte_present(*pte))
 483                        break;
 484
 485                printk(KERN_DEBUG "clearing pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx pte: %p pte phys: %lx\n",
 486                                pfn, pmd, __pa(pmd), pte, __pa(pte));
 487                pte_clear(NULL, va, pte);
 488        }
 489        paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
 490        paging_init();
 491}
 492
 493/*
 494 * Build a proper pagetable for the kernel mappings.  Up until this
 495 * point, we've been running on some set of pagetables constructed by
 496 * the boot process.
 497 *
 498 * If we're booting on native hardware, this will be a pagetable
 499 * constructed in arch/x86/kernel/head_32.S.  The root of the
 500 * pagetable will be swapper_pg_dir.
 501 *
 502 * If we're booting paravirtualized under a hypervisor, then there are
 503 * more options: we may already be running PAE, and the pagetable may
 504 * or may not be based in swapper_pg_dir.  In any case,
 505 * paravirt_pagetable_init() will set up swapper_pg_dir
 506 * appropriately for the rest of the initialization to work.
 507 *
 508 * In general, pagetable_init() assumes that the pagetable may already
 509 * be partially populated, and so it avoids stomping on any existing
 510 * mappings.
 511 */
 512void __init early_ioremap_page_table_range_init(void)
 513{
 514        pgd_t *pgd_base = swapper_pg_dir;
 515        unsigned long vaddr, end;
 516
 517        /*
 518         * Fixed mappings, only the page table structure has to be
 519         * created - mappings will be set by set_fixmap():
 520         */
 521        vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 522        end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
 523        page_table_range_init(vaddr, end, pgd_base);
 524        early_ioremap_reset();
 525}
 526
 527static void __init pagetable_init(void)
 528{
 529        pgd_t *pgd_base = swapper_pg_dir;
 530
 531        permanent_kmaps_init(pgd_base);
 532}
 533
 534#define DEFAULT_PTE_MASK ~(_PAGE_NX | _PAGE_GLOBAL)
 535/* Bits supported by the hardware: */
 536pteval_t __supported_pte_mask __read_mostly = DEFAULT_PTE_MASK;
 537/* Bits allowed in normal kernel mappings: */
 538pteval_t __default_kernel_pte_mask __read_mostly = DEFAULT_PTE_MASK;
 539EXPORT_SYMBOL_GPL(__supported_pte_mask);
 540/* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */
 541EXPORT_SYMBOL(__default_kernel_pte_mask);
 542
 543/* user-defined highmem size */
 544static unsigned int highmem_pages = -1;
 545
 546/*
 547 * highmem=size forces highmem to be exactly 'size' bytes.
 548 * This works even on boxes that have no highmem otherwise.
 549 * This also works to reduce highmem size on bigger boxes.
 550 */
 551static int __init parse_highmem(char *arg)
 552{
 553        if (!arg)
 554                return -EINVAL;
 555
 556        highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
 557        return 0;
 558}
 559early_param("highmem", parse_highmem);
 560
 561#define MSG_HIGHMEM_TOO_BIG \
 562        "highmem size (%luMB) is bigger than pages available (%luMB)!\n"
 563
 564#define MSG_LOWMEM_TOO_SMALL \
 565        "highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
 566/*
 567 * All of RAM fits into lowmem - but if user wants highmem
 568 * artificially via the highmem=x boot parameter then create
 569 * it:
 570 */
 571static void __init lowmem_pfn_init(void)
 572{
 573        /* max_low_pfn is 0, we already have early_res support */
 574        max_low_pfn = max_pfn;
 575
 576        if (highmem_pages == -1)
 577                highmem_pages = 0;
 578#ifdef CONFIG_HIGHMEM
 579        if (highmem_pages >= max_pfn) {
 580                printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
 581                        pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
 582                highmem_pages = 0;
 583        }
 584        if (highmem_pages) {
 585                if (max_low_pfn - highmem_pages < 64*1024*1024/PAGE_SIZE) {
 586                        printk(KERN_ERR MSG_LOWMEM_TOO_SMALL,
 587                                pages_to_mb(highmem_pages));
 588                        highmem_pages = 0;
 589                }
 590                max_low_pfn -= highmem_pages;
 591        }
 592#else
 593        if (highmem_pages)
 594                printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
 595#endif
 596}
 597
 598#define MSG_HIGHMEM_TOO_SMALL \
 599        "only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
 600
 601#define MSG_HIGHMEM_TRIMMED \
 602        "Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
 603/*
 604 * We have more RAM than fits into lowmem - we try to put it into
 605 * highmem, also taking the highmem=x boot parameter into account:
 606 */
 607static void __init highmem_pfn_init(void)
 608{
 609        max_low_pfn = MAXMEM_PFN;
 610
 611        if (highmem_pages == -1)
 612                highmem_pages = max_pfn - MAXMEM_PFN;
 613
 614        if (highmem_pages + MAXMEM_PFN < max_pfn)
 615                max_pfn = MAXMEM_PFN + highmem_pages;
 616
 617        if (highmem_pages + MAXMEM_PFN > max_pfn) {
 618                printk(KERN_WARNING MSG_HIGHMEM_TOO_SMALL,
 619                        pages_to_mb(max_pfn - MAXMEM_PFN),
 620                        pages_to_mb(highmem_pages));
 621                highmem_pages = 0;
 622        }
 623#ifndef CONFIG_HIGHMEM
 624        /* Maximum memory usable is what is directly addressable */
 625        printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
 626        if (max_pfn > MAX_NONPAE_PFN)
 627                printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
 628        else
 629                printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
 630        max_pfn = MAXMEM_PFN;
 631#else /* !CONFIG_HIGHMEM */
 632#ifndef CONFIG_HIGHMEM64G
 633        if (max_pfn > MAX_NONPAE_PFN) {
 634                max_pfn = MAX_NONPAE_PFN;
 635                printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
 636        }
 637#endif /* !CONFIG_HIGHMEM64G */
 638#endif /* !CONFIG_HIGHMEM */
 639}
 640
 641/*
 642 * Determine low and high memory ranges:
 643 */
 644void __init find_low_pfn_range(void)
 645{
 646        /* it could update max_pfn */
 647
 648        if (max_pfn <= MAXMEM_PFN)
 649                lowmem_pfn_init();
 650        else
 651                highmem_pfn_init();
 652}
 653
 654#ifndef CONFIG_NUMA
 655void __init initmem_init(void)
 656{
 657#ifdef CONFIG_HIGHMEM
 658        highstart_pfn = highend_pfn = max_pfn;
 659        if (max_pfn > max_low_pfn)
 660                highstart_pfn = max_low_pfn;
 661        printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
 662                pages_to_mb(highend_pfn - highstart_pfn));
 663        high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
 664#else
 665        high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
 666#endif
 667
 668        memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
 669
 670#ifdef CONFIG_FLATMEM
 671        max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
 672#endif
 673        __vmalloc_start_set = true;
 674
 675        printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
 676                        pages_to_mb(max_low_pfn));
 677
 678        setup_bootmem_allocator();
 679}
 680#endif /* !CONFIG_NUMA */
 681
 682void __init setup_bootmem_allocator(void)
 683{
 684        printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
 685                 max_pfn_mapped<<PAGE_SHIFT);
 686        printk(KERN_INFO "  low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);
 687}
 688
 689/*
 690 * paging_init() sets up the page tables - note that the first 8MB are
 691 * already mapped by head.S.
 692 *
 693 * This routines also unmaps the page at virtual kernel address 0, so
 694 * that we can trap those pesky NULL-reference errors in the kernel.
 695 */
 696void __init paging_init(void)
 697{
 698        pagetable_init();
 699
 700        __flush_tlb_all();
 701
 702        /*
 703         * NOTE: at this point the bootmem allocator is fully available.
 704         */
 705        olpc_dt_build_devicetree();
 706        sparse_init();
 707        zone_sizes_init();
 708}
 709
 710/*
 711 * Test if the WP bit works in supervisor mode. It isn't supported on 386's
 712 * and also on some strange 486's. All 586+'s are OK. This used to involve
 713 * black magic jumps to work around some nasty CPU bugs, but fortunately the
 714 * switch to using exceptions got rid of all that.
 715 */
 716static void __init test_wp_bit(void)
 717{
 718        char z = 0;
 719
 720        printk(KERN_INFO "Checking if this processor honours the WP bit even in supervisor mode...");
 721
 722        __set_fixmap(FIX_WP_TEST, __pa_symbol(empty_zero_page), PAGE_KERNEL_RO);
 723
 724        if (copy_to_kernel_nofault((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
 725                clear_fixmap(FIX_WP_TEST);
 726                printk(KERN_CONT "Ok.\n");
 727                return;
 728        }
 729
 730        printk(KERN_CONT "No.\n");
 731        panic("Linux doesn't support CPUs with broken WP.");
 732}
 733
 734void __init mem_init(void)
 735{
 736        pci_iommu_alloc();
 737
 738#ifdef CONFIG_FLATMEM
 739        BUG_ON(!mem_map);
 740#endif
 741        /*
 742         * With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
 743         * be done before memblock_free_all(). Memblock use free low memory for
 744         * temporary data (see find_range_array()) and for this purpose can use
 745         * pages that was already passed to the buddy allocator, hence marked as
 746         * not accessible in the page tables when compiled with
 747         * CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
 748         * important here.
 749         */
 750        set_highmem_pages_init();
 751
 752        /* this will put all low memory onto the freelists */
 753        memblock_free_all();
 754
 755        after_bootmem = 1;
 756        x86_init.hyper.init_after_bootmem();
 757
 758        /*
 759         * Check boundaries twice: Some fundamental inconsistencies can
 760         * be detected at build time already.
 761         */
 762#define __FIXADDR_TOP (-PAGE_SIZE)
 763#ifdef CONFIG_HIGHMEM
 764        BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE  > FIXADDR_START);
 765        BUILD_BUG_ON(VMALLOC_END                        > PKMAP_BASE);
 766#endif
 767#define high_memory (-128UL << 20)
 768        BUILD_BUG_ON(VMALLOC_START                      >= VMALLOC_END);
 769#undef high_memory
 770#undef __FIXADDR_TOP
 771
 772#ifdef CONFIG_HIGHMEM
 773        BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE        > FIXADDR_START);
 774        BUG_ON(VMALLOC_END                              > PKMAP_BASE);
 775#endif
 776        BUG_ON(VMALLOC_START                            >= VMALLOC_END);
 777        BUG_ON((unsigned long)high_memory               > VMALLOC_START);
 778
 779        test_wp_bit();
 780}
 781
 782#ifdef CONFIG_MEMORY_HOTPLUG
 783int arch_add_memory(int nid, u64 start, u64 size,
 784                    struct mhp_params *params)
 785{
 786        unsigned long start_pfn = start >> PAGE_SHIFT;
 787        unsigned long nr_pages = size >> PAGE_SHIFT;
 788        int ret;
 789
 790        /*
 791         * The page tables were already mapped at boot so if the caller
 792         * requests a different mapping type then we must change all the
 793         * pages with __set_memory_prot().
 794         */
 795        if (params->pgprot.pgprot != PAGE_KERNEL.pgprot) {
 796                ret = __set_memory_prot(start, nr_pages, params->pgprot);
 797                if (ret)
 798                        return ret;
 799        }
 800
 801        return __add_pages(nid, start_pfn, nr_pages, params);
 802}
 803
 804void arch_remove_memory(int nid, u64 start, u64 size,
 805                        struct vmem_altmap *altmap)
 806{
 807        unsigned long start_pfn = start >> PAGE_SHIFT;
 808        unsigned long nr_pages = size >> PAGE_SHIFT;
 809
 810        __remove_pages(start_pfn, nr_pages, altmap);
 811}
 812#endif
 813
 814int kernel_set_to_readonly __read_mostly;
 815
 816static void mark_nxdata_nx(void)
 817{
 818        /*
 819         * When this called, init has already been executed and released,
 820         * so everything past _etext should be NX.
 821         */
 822        unsigned long start = PFN_ALIGN(_etext);
 823        /*
 824         * This comes from __is_kernel_text upper limit. Also HPAGE where used:
 825         */
 826        unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
 827
 828        if (__supported_pte_mask & _PAGE_NX)
 829                printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
 830        set_memory_nx(start, size >> PAGE_SHIFT);
 831}
 832
 833void mark_rodata_ro(void)
 834{
 835        unsigned long start = PFN_ALIGN(_text);
 836        unsigned long size = (unsigned long)__end_rodata - start;
 837
 838        set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
 839        pr_info("Write protecting kernel text and read-only data: %luk\n",
 840                size >> 10);
 841
 842        kernel_set_to_readonly = 1;
 843
 844#ifdef CONFIG_CPA_DEBUG
 845        pr_info("Testing CPA: Reverting %lx-%lx\n", start, start + size);
 846        set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
 847
 848        pr_info("Testing CPA: write protecting again\n");
 849        set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
 850#endif
 851        mark_nxdata_nx();
 852        if (__supported_pte_mask & _PAGE_NX)
 853                debug_checkwx();
 854}
 855
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