arch/x86/kernel/machine_kexec_64.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * handle transition of Linux booting another kernel
   4  * Copyright (C) 2002-2005 Eric Biederman  <[email protected]>
   5  */
   6
   7 #define pr_fmt(fmt)     "kexec: " fmt
   8
   9 #include <linux/mm.h>
  10 #include <linux/kexec.h>
  11 #include <linux/string.h>
  12 #include <linux/gfp.h>
  13 #include <linux/reboot.h>
  14 #include <linux/numa.h>
  15 #include <linux/ftrace.h>
  16 #include <linux/io.h>
  17 #include <linux/suspend.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/efi.h>
  20 #include <linux/cc_platform.h>
  21
  22 #include <asm/init.h>
  23 #include <asm/tlbflush.h>
  24 #include <asm/mmu_context.h>
  25 #include <asm/io_apic.h>
  26 #include <asm/debugreg.h>
  27 #include <asm/kexec-bzimage64.h>
  28 #include <asm/setup.h>
  29 #include <asm/set_memory.h>
  30 #include <asm/cpu.h>
  31
  32 #ifdef CONFIG_ACPI
  33 /*
  34  * Used while adding mapping for ACPI tables.
  35  * Can be reused when other iomem regions need be mapped
  36  */
  37 struct init_pgtable_data {
  38         struct x86_mapping_info *info;
  39         pgd_t *level4p;
  40 };
  41
  42 static int mem_region_callback(struct resource *res, void *arg)
  43 {
  44         struct init_pgtable_data *data = arg;
  45         unsigned long mstart, mend;
  46
  47         mstart = res->start;
  48         mend = mstart + resource_size(res) - 1;
  49
  50         return kernel_ident_mapping_init(data->info, data->level4p, mstart, mend);
  51 }
  52
  53 static int
  54 map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p)
  55 {
  56         struct init_pgtable_data data;
  57         unsigned long flags;
  58         int ret;
  59
  60         data.info = info;
  61         data.level4p = level4p;
  62         flags = IORESOURCE_MEM | IORESOURCE_BUSY;
  63
  64         ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
  65                                   &data, mem_region_callback);
  66         if (ret && ret != -EINVAL)
  67                 return ret;
  68
  69         /* ACPI tables could be located in ACPI Non-volatile Storage region */
  70         ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1,
  71                                   &data, mem_region_callback);
  72         if (ret && ret != -EINVAL)
  73                 return ret;
  74
  75         return 0;
  76 }
  77 #else
  78 static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }
  79 #endif
  80
  81 #ifdef CONFIG_KEXEC_FILE
  82 const struct kexec_file_ops * const kexec_file_loaders[] = {
  83                 &kexec_bzImage64_ops,
  84                 NULL
  85 };
  86 #endif
  87
  88 static int
  89 map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p)
  90 {
  91 #ifdef CONFIG_EFI
  92         unsigned long mstart, mend;
  93
  94         if (!efi_enabled(EFI_BOOT))
  95                 return 0;
  96
  97         mstart = (boot_params.efi_info.efi_systab |
  98                         ((u64)boot_params.efi_info.efi_systab_hi<<32));
  99
 100         if (efi_enabled(EFI_64BIT))
 101                 mend = mstart + sizeof(efi_system_table_64_t);
 102         else
 103                 mend = mstart + sizeof(efi_system_table_32_t);
 104
 105         if (!mstart)
 106                 return 0;
 107
 108         return kernel_ident_mapping_init(info, level4p, mstart, mend);
 109 #endif
 110         return 0;
 111 }
 112
 113 static void free_transition_pgtable(struct kimage *image)
 114 {
 115         free_page((unsigned long)image->arch.p4d);
 116         image->arch.p4d = NULL;
 117         free_page((unsigned long)image->arch.pud);
 118         image->arch.pud = NULL;
 119         free_page((unsigned long)image->arch.pmd);
 120         image->arch.pmd = NULL;
 121         free_page((unsigned long)image->arch.pte);
 122         image->arch.pte = NULL;
 123 }
 124
 125 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
 126 {
 127         pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
 128         unsigned long vaddr, paddr;
 129         int result = -ENOMEM;
 130         p4d_t *p4d;
 131         pud_t *pud;
 132         pmd_t *pmd;
 133         pte_t *pte;
 134
 135         vaddr = (unsigned long)relocate_kernel;
 136         paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
 137         pgd += pgd_index(vaddr);
 138         if (!pgd_present(*pgd)) {
 139                 p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
 140                 if (!p4d)
 141                         goto err;
 142                 image->arch.p4d = p4d;
 143                 set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
 144         }
 145         p4d = p4d_offset(pgd, vaddr);
 146         if (!p4d_present(*p4d)) {
 147                 pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
 148                 if (!pud)
 149                         goto err;
 150                 image->arch.pud = pud;
 151                 set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
 152         }
 153         pud = pud_offset(p4d, vaddr);
 154         if (!pud_present(*pud)) {
 155                 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 156                 if (!pmd)
 157                         goto err;
 158                 image->arch.pmd = pmd;
 159                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
 160         }
 161         pmd = pmd_offset(pud, vaddr);
 162         if (!pmd_present(*pmd)) {
 163                 pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
 164                 if (!pte)
 165                         goto err;
 166                 image->arch.pte = pte;
 167                 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
 168         }
 169         pte = pte_offset_kernel(pmd, vaddr);
 170
 171         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
 172                 prot = PAGE_KERNEL_EXEC;
 173
 174         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
 175         return 0;
 176 err:
 177         return result;
 178 }
 179
 180 static void *alloc_pgt_page(void *data)
 181 {
 182         struct kimage *image = (struct kimage *)data;
 183         struct page *page;
 184         void *p = NULL;
 185
 186         page = kimage_alloc_control_pages(image, 0);
 187         if (page) {
 188                 p = page_address(page);
 189                 clear_page(p);
 190         }
 191
 192         return p;
 193 }
 194
 195 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 196 {
 197         struct x86_mapping_info info = {
 198                 .alloc_pgt_page = alloc_pgt_page,
 199                 .context        = image,
 200                 .page_flag      = __PAGE_KERNEL_LARGE_EXEC,
 201                 .kernpg_flag    = _KERNPG_TABLE_NOENC,
 202         };
 203         unsigned long mstart, mend;
 204         pgd_t *level4p;
 205         int result;
 206         int i;
 207
 208         level4p = (pgd_t *)__va(start_pgtable);
 209         clear_page(level4p);
 210
 211         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
 212                 info.page_flag   |= _PAGE_ENC;
 213                 info.kernpg_flag |= _PAGE_ENC;
 214         }
 215
 216         if (direct_gbpages)
 217                 info.direct_gbpages = true;
 218
 219         for (i = 0; i < nr_pfn_mapped; i++) {
 220                 mstart = pfn_mapped[i].start << PAGE_SHIFT;
 221                 mend   = pfn_mapped[i].end << PAGE_SHIFT;
 222
 223                 result = kernel_ident_mapping_init(&info,
 224                                                  level4p, mstart, mend);
 225                 if (result)
 226                         return result;
 227         }
 228
 229         /*
 230          * segments's mem ranges could be outside 0 ~ max_pfn,
 231          * for example when jump back to original kernel from kexeced kernel.
 232          * or first kernel is booted with user mem map, and second kernel
 233          * could be loaded out of that range.
 234          */
 235         for (i = 0; i < image->nr_segments; i++) {
 236                 mstart = image->segment[i].mem;
 237                 mend   = mstart + image->segment[i].memsz;
 238
 239                 result = kernel_ident_mapping_init(&info,
 240                                                  level4p, mstart, mend);
 241
 242                 if (result)
 243                         return result;
 244         }
 245
 246         /*
 247          * Prepare EFI systab and ACPI tables for kexec kernel since they are
 248          * not covered by pfn_mapped.
 249          */
 250         result = map_efi_systab(&info, level4p);
 251         if (result)
 252                 return result;
 253
 254         result = map_acpi_tables(&info, level4p);
 255         if (result)
 256                 return result;
 257
 258         return init_transition_pgtable(image, level4p);
 259 }
 260
 261 static void load_segments(void)
 262 {
 263         __asm__ __volatile__ (
 264                 "\tmovl %0,%%ds\n"
 265                 "\tmovl %0,%%es\n"
 266                 "\tmovl %0,%%ss\n"
 267                 "\tmovl %0,%%fs\n"
 268                 "\tmovl %0,%%gs\n"
 269                 : : "a" (__KERNEL_DS) : "memory"
 270                 );
 271 }
 272
 273 int machine_kexec_prepare(struct kimage *image)
 274 {
 275         unsigned long start_pgtable;
 276         int result;
 277
 278         /* Calculate the offsets */
 279         start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
 280
 281         /* Setup the identity mapped 64bit page table */
 282         result = init_pgtable(image, start_pgtable);
 283         if (result)
 284                 return result;
 285
 286         return 0;
 287 }
 288
 289 void machine_kexec_cleanup(struct kimage *image)
 290 {
 291         free_transition_pgtable(image);
 292 }
 293
 294 /*
 295  * Do not allocate memory (or fail in any way) in machine_kexec().
 296  * We are past the point of no return, committed to rebooting now.
 297  */
 298 void machine_kexec(struct kimage *image)
 299 {
 300         unsigned long page_list[PAGES_NR];
 301         void *control_page;
 302         int save_ftrace_enabled;
 303
 304 #ifdef CONFIG_KEXEC_JUMP
 305         if (image->preserve_context)
 306                 save_processor_state();
 307 #endif
 308
 309         save_ftrace_enabled = __ftrace_enabled_save();
 310
 311         /* Interrupts aren't acceptable while we reboot */
 312         local_irq_disable();
 313         hw_breakpoint_disable();
 314         cet_disable();
 315
 316         if (image->preserve_context) {
 317 #ifdef CONFIG_X86_IO_APIC
 318                 /*
 319                  * We need to put APICs in legacy mode so that we can
 320                  * get timer interrupts in second kernel. kexec/kdump
 321                  * paths already have calls to restore_boot_irq_mode()
 322                  * in one form or other. kexec jump path also need one.
 323                  */
 324                 clear_IO_APIC();
 325                 restore_boot_irq_mode();
 326 #endif
 327         }
 328
 329         control_page = page_address(image->control_code_page) + PAGE_SIZE;
 330         __memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 331
 332         page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
 333         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 334         page_list[PA_TABLE_PAGE] =
 335           (unsigned long)__pa(page_address(image->control_code_page));
 336
 337         if (image->type == KEXEC_TYPE_DEFAULT)
 338                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 339                                                 << PAGE_SHIFT);
 340
 341         /*
 342          * The segment registers are funny things, they have both a
 343          * visible and an invisible part.  Whenever the visible part is
 344          * set to a specific selector, the invisible part is loaded
 345          * with from a table in memory.  At no other time is the
 346          * descriptor table in memory accessed.
 347          *
 348          * I take advantage of this here by force loading the
 349          * segments, before I zap the gdt with an invalid value.
 350          */
 351         load_segments();
 352         /*
 353          * The gdt & idt are now invalid.
 354          * If you want to load them you must set up your own idt & gdt.
 355          */
 356         native_idt_invalidate();
 357         native_gdt_invalidate();
 358
 359         /* now call it */
 360         image->start = relocate_kernel((unsigned long)image->head,
 361                                        (unsigned long)page_list,
 362                                        image->start,
 363                                        image->preserve_context,
 364                                        cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT));
 365
 366 #ifdef CONFIG_KEXEC_JUMP
 367         if (image->preserve_context)
 368                 restore_processor_state();
 369 #endif
 370
 371         __ftrace_enabled_restore(save_ftrace_enabled);
 372 }
 373
 374 /* arch-dependent functionality related to kexec file-based syscall */
 375
 376 #ifdef CONFIG_KEXEC_FILE
 377 void *arch_kexec_kernel_image_load(struct kimage *image)
 378 {
 379         if (!image->fops || !image->fops->load)
 380                 return ERR_PTR(-ENOEXEC);
 381
 382         return image->fops->load(image, image->kernel_buf,
 383                                  image->kernel_buf_len, image->initrd_buf,
 384                                  image->initrd_buf_len, image->cmdline_buf,
 385                                  image->cmdline_buf_len);
 386 }
 387
 388 /*
 389  * Apply purgatory relocations.
 390  *
 391  * @pi:         Purgatory to be relocated.
 392  * @section:    Section relocations applying to.
 393  * @relsec:     Section containing RELAs.
 394  * @symtabsec:  Corresponding symtab.
 395  *
 396  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
 397  */
 398 int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
 399                                      Elf_Shdr *section, const Elf_Shdr *relsec,
 400                                      const Elf_Shdr *symtabsec)
 401 {
 402         unsigned int i;
 403         Elf64_Rela *rel;
 404         Elf64_Sym *sym;
 405         void *location;
 406         unsigned long address, sec_base, value;
 407         const char *strtab, *name, *shstrtab;
 408         const Elf_Shdr *sechdrs;
 409
 410         /* String & section header string table */
 411         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 412         strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset;
 413         shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
 414
 415         rel = (void *)pi->ehdr + relsec->sh_offset;
 416
 417         pr_debug("Applying relocate section %s to %u\n",
 418                  shstrtab + relsec->sh_name, relsec->sh_info);
 419
 420         for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) {
 421
 422                 /*
 423                  * rel[i].r_offset contains byte offset from beginning
 424                  * of section to the storage unit affected.
 425                  *
 426                  * This is location to update. This is temporary buffer
 427                  * where section is currently loaded. This will finally be
 428                  * loaded to a different address later, pointed to by
 429                  * ->sh_addr. kexec takes care of moving it
 430                  *  (kexec_load_segment()).
 431                  */
 432                 location = pi->purgatory_buf;
 433                 location += section->sh_offset;
 434                 location += rel[i].r_offset;
 435
 436                 /* Final address of the location */
 437                 address = section->sh_addr + rel[i].r_offset;
 438
 439                 /*
 440                  * rel[i].r_info contains information about symbol table index
 441                  * w.r.t which relocation must be made and type of relocation
 442                  * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
 443                  * these respectively.
 444                  */
 445                 sym = (void *)pi->ehdr + symtabsec->sh_offset;
 446                 sym += ELF64_R_SYM(rel[i].r_info);
 447
 448                 if (sym->st_name)
 449                         name = strtab + sym->st_name;
 450                 else
 451                         name = shstrtab + sechdrs[sym->st_shndx].sh_name;
 452
 453                 pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
 454                          name, sym->st_info, sym->st_shndx, sym->st_value,
 455                          sym->st_size);
 456
 457                 if (sym->st_shndx == SHN_UNDEF) {
 458                         pr_err("Undefined symbol: %s\n", name);
 459                         return -ENOEXEC;
 460                 }
 461
 462                 if (sym->st_shndx == SHN_COMMON) {
 463                         pr_err("symbol '%s' in common section\n", name);
 464                         return -ENOEXEC;
 465                 }
 466
 467                 if (sym->st_shndx == SHN_ABS)
 468                         sec_base = 0;
 469                 else if (sym->st_shndx >= pi->ehdr->e_shnum) {
 470                         pr_err("Invalid section %d for symbol %s\n",
 471                                sym->st_shndx, name);
 472                         return -ENOEXEC;
 473                 } else
 474                         sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
 475
 476                 value = sym->st_value;
 477                 value += sec_base;
 478                 value += rel[i].r_addend;
 479
 480                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 481                 case R_X86_64_NONE:
 482                         break;
 483                 case R_X86_64_64:
 484                         *(u64 *)location = value;
 485                         break;
 486                 case R_X86_64_32:
 487                         *(u32 *)location = value;
 488                         if (value != *(u32 *)location)
 489                                 goto overflow;
 490                         break;
 491                 case R_X86_64_32S:
 492                         *(s32 *)location = value;
 493                         if ((s64)value != *(s32 *)location)
 494                                 goto overflow;
 495                         break;
 496                 case R_X86_64_PC32:
 497                 case R_X86_64_PLT32:
 498                         value -= (u64)address;
 499                         *(u32 *)location = value;
 500                         break;
 501                 default:
 502                         pr_err("Unknown rela relocation: %llu\n",
 503                                ELF64_R_TYPE(rel[i].r_info));
 504                         return -ENOEXEC;
 505                 }
 506         }
 507         return 0;
 508
 509 overflow:
 510         pr_err("Overflow in relocation type %d value 0x%lx\n",
 511                (int)ELF64_R_TYPE(rel[i].r_info), value);
 512         return -ENOEXEC;
 513 }
 514
 515 int arch_kimage_file_post_load_cleanup(struct kimage *image)
 516 {
 517         vfree(image->elf_headers);
 518         image->elf_headers = NULL;
 519         image->elf_headers_sz = 0;
 520
 521         return kexec_image_post_load_cleanup_default(image);
 522 }
 523 #endif /* CONFIG_KEXEC_FILE */
 524
 525 static int
 526 kexec_mark_range(unsigned long start, unsigned long end, bool protect)
 527 {
 528         struct page *page;
 529         unsigned int nr_pages;
 530
 531         /*
 532          * For physical range: [start, end]. We must skip the unassigned
 533          * crashk resource with zero-valued "end" member.
 534          */
 535         if (!end || start > end)
 536                 return 0;
 537
 538         page = pfn_to_page(start >> PAGE_SHIFT);
 539         nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
 540         if (protect)
 541                 return set_pages_ro(page, nr_pages);
 542         else
 543                 return set_pages_rw(page, nr_pages);
 544 }
 545
 546 static void kexec_mark_crashkres(bool protect)
 547 {
 548         unsigned long control;
 549
 550         kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
 551
 552         /* Don't touch the control code page used in crash_kexec().*/
 553         control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
 554         /* Control code page is located in the 2nd page. */
 555         kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
 556         control += KEXEC_CONTROL_PAGE_SIZE;
 557         kexec_mark_range(control, crashk_res.end, protect);
 558 }
 559
 560 void arch_kexec_protect_crashkres(void)
 561 {
 562         kexec_mark_crashkres(true);
 563 }
 564
 565 void arch_kexec_unprotect_crashkres(void)
 566 {
 567         kexec_mark_crashkres(false);
 568 }
 569
 570 /*
 571  * During a traditional boot under SME, SME will encrypt the kernel,
 572  * so the SME kexec kernel also needs to be un-encrypted in order to
 573  * replicate a normal SME boot.
 574  *
 575  * During a traditional boot under SEV, the kernel has already been
 576  * loaded encrypted, so the SEV kexec kernel needs to be encrypted in
 577  * order to replicate a normal SEV boot.
 578  */
 579 int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, gfp_t gfp)
 580 {
 581         if (!cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
 582                 return 0;
 583
 584         /*
 585          * If host memory encryption is active we need to be sure that kexec
 586          * pages are not encrypted because when we boot to the new kernel the
 587          * pages won't be accessed encrypted (initially).
 588          */
 589         return set_memory_decrypted((unsigned long)vaddr, pages);
 590 }
 591
 592 void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages)
 593 {
 594         if (!cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
 595                 return;
 596
 597         /*
 598          * If host memory encryption is active we need to reset the pages back
 599          * to being an encrypted mapping before freeing them.
 600          */
 601         set_memory_encrypted((unsigned long)vaddr, pages);
 602 }