1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * handle transition of Linux booting another kernel 4 * Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com> 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 21 #include <asm/init.h> 22 #include <asm/pgtable.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 31 #ifdef CONFIG_ACPI 32 /* 33 * Used while adding mapping for ACPI tables. 34 * Can be reused when other iomem regions need be mapped 35 */ 36 struct init_pgtable_data { 37 struct x86_mapping_info *info; 38 pgd_t *level4p; 39 }; 40 41 static int mem_region_callback(struct resource *res, void *arg) 42 { 43 struct init_pgtable_data *data = arg; 44 unsigned long mstart, mend; 45 46 mstart = res->start; 47 mend = mstart + resource_size(res) - 1; 48 49 return kernel_ident_mapping_init(data->info, data->level4p, mstart, mend); 50 } 51 52 static int 53 map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) 54 { 55 struct init_pgtable_data data; 56 unsigned long flags; 57 int ret; 58 59 data.info = info; 60 data.level4p = level4p; 61 flags = IORESOURCE_MEM | IORESOURCE_BUSY; 62 63 ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, 64 &data, mem_region_callback); 65 if (ret && ret != -EINVAL) 66 return ret; 67 68 /* ACPI tables could be located in ACPI Non-volatile Storage region */ 69 ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, 70 &data, mem_region_callback); 71 if (ret && ret != -EINVAL) 72 return ret; 73 74 return 0; 75 } 76 #else 77 static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; } 78 #endif 79 80 #ifdef CONFIG_KEXEC_FILE 81 const struct kexec_file_ops * const kexec_file_loaders[] = { 82 &kexec_bzImage64_ops, 83 NULL 84 }; 85 #endif 86 87 static int 88 map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p) 89 { 90 #ifdef CONFIG_EFI 91 unsigned long mstart, mend; 92 93 if (!efi_enabled(EFI_BOOT)) 94 return 0; 95 96 mstart = (boot_params.efi_info.efi_systab | 97 ((u64)boot_params.efi_info.efi_systab_hi<<32)); 98 99 if (efi_enabled(EFI_64BIT)) 100 mend = mstart + sizeof(efi_system_table_64_t); 101 else 102 mend = mstart + sizeof(efi_system_table_32_t); 103 104 if (!mstart) 105 return 0; 106 107 return kernel_ident_mapping_init(info, level4p, mstart, mend); 108 #endif 109 return 0; 110 } 111 112 static void free_transition_pgtable(struct kimage *image) 113 { 114 free_page((unsigned long)image->arch.p4d); 115 image->arch.p4d = NULL; 116 free_page((unsigned long)image->arch.pud); 117 image->arch.pud = NULL; 118 free_page((unsigned long)image->arch.pmd); 119 image->arch.pmd = NULL; 120 free_page((unsigned long)image->arch.pte); 121 image->arch.pte = NULL; 122 } 123 124 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) 125 { 126 pgprot_t prot = PAGE_KERNEL_EXEC_NOENC; 127 unsigned long vaddr, paddr; 128 int result = -ENOMEM; 129 p4d_t *p4d; 130 pud_t *pud; 131 pmd_t *pmd; 132 pte_t *pte; 133 134 vaddr = (unsigned long)relocate_kernel; 135 paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE); 136 pgd += pgd_index(vaddr); 137 if (!pgd_present(*pgd)) { 138 p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL); 139 if (!p4d) 140 goto err; 141 image->arch.p4d = p4d; 142 set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE)); 143 } 144 p4d = p4d_offset(pgd, vaddr); 145 if (!p4d_present(*p4d)) { 146 pud = (pud_t *)get_zeroed_page(GFP_KERNEL); 147 if (!pud) 148 goto err; 149 image->arch.pud = pud; 150 set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE)); 151 } 152 pud = pud_offset(p4d, vaddr); 153 if (!pud_present(*pud)) { 154 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL); 155 if (!pmd) 156 goto err; 157 image->arch.pmd = pmd; 158 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE)); 159 } 160 pmd = pmd_offset(pud, vaddr); 161 if (!pmd_present(*pmd)) { 162 pte = (pte_t *)get_zeroed_page(GFP_KERNEL); 163 if (!pte) 164 goto err; 165 image->arch.pte = pte; 166 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE)); 167 } 168 pte = pte_offset_kernel(pmd, vaddr); 169 170 if (sev_active()) 171 prot = PAGE_KERNEL_EXEC; 172 173 set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot)); 174 return 0; 175 err: 176 return result; 177 } 178 179 static void *alloc_pgt_page(void *data) 180 { 181 struct kimage *image = (struct kimage *)data; 182 struct page *page; 183 void *p = NULL; 184 185 page = kimage_alloc_control_pages(image, 0); 186 if (page) { 187 p = page_address(page); 188 clear_page(p); 189 } 190 191 return p; 192 } 193 194 static int init_pgtable(struct kimage *image, unsigned long start_pgtable) 195 { 196 struct x86_mapping_info info = { 197 .alloc_pgt_page = alloc_pgt_page, 198 .context = image, 199 .page_flag = __PAGE_KERNEL_LARGE_EXEC, 200 .kernpg_flag = _KERNPG_TABLE_NOENC, 201 }; 202 unsigned long mstart, mend; 203 pgd_t *level4p; 204 int result; 205 int i; 206 207 level4p = (pgd_t *)__va(start_pgtable); 208 clear_page(level4p); 209 210 if (sev_active()) { 211 info.page_flag |= _PAGE_ENC; 212 info.kernpg_flag |= _PAGE_ENC; 213 } 214 215 if (direct_gbpages) 216 info.direct_gbpages = true; 217 218 for (i = 0; i < nr_pfn_mapped; i++) { 219 mstart = pfn_mapped[i].start << PAGE_SHIFT; 220 mend = pfn_mapped[i].end << PAGE_SHIFT; 221 222 result = kernel_ident_mapping_init(&info, 223 level4p, mstart, mend); 224 if (result) 225 return result; 226 } 227 228 /* 229 * segments's mem ranges could be outside 0 ~ max_pfn, 230 * for example when jump back to original kernel from kexeced kernel. 231 * or first kernel is booted with user mem map, and second kernel 232 * could be loaded out of that range. 233 */ 234 for (i = 0; i < image->nr_segments; i++) { 235 mstart = image->segment[i].mem; 236 mend = mstart + image->segment[i].memsz; 237 238 result = kernel_ident_mapping_init(&info, 239 level4p, mstart, mend); 240 241 if (result) 242 return result; 243 } 244 245 /* 246 * Prepare EFI systab and ACPI tables for kexec kernel since they are 247 * not covered by pfn_mapped. 248 */ 249 result = map_efi_systab(&info, level4p); 250 if (result) 251 return result; 252 253 result = map_acpi_tables(&info, level4p); 254 if (result) 255 return result; 256 257 return init_transition_pgtable(image, level4p); 258 } 259 260 static void set_idt(void *newidt, u16 limit) 261 { 262 struct desc_ptr curidt; 263 264 /* x86-64 supports unaliged loads & stores */ 265 curidt.size = limit; 266 curidt.address = (unsigned long)newidt; 267 268 __asm__ __volatile__ ( 269 "lidtq %0\n" 270 : : "m" (curidt) 271 ); 272 }; 273 274 275 static void set_gdt(void *newgdt, u16 limit) 276 { 277 struct desc_ptr curgdt; 278 279 /* x86-64 supports unaligned loads & stores */ 280 curgdt.size = limit; 281 curgdt.address = (unsigned long)newgdt; 282 283 __asm__ __volatile__ ( 284 "lgdtq %0\n" 285 : : "m" (curgdt) 286 ); 287 }; 288 289 static void load_segments(void) 290 { 291 __asm__ __volatile__ ( 292 "\tmovl %0,%%ds\n" 293 "\tmovl %0,%%es\n" 294 "\tmovl %0,%%ss\n" 295 "\tmovl %0,%%fs\n" 296 "\tmovl %0,%%gs\n" 297 : : "a" (__KERNEL_DS) : "memory" 298 ); 299 } 300 301 int machine_kexec_prepare(struct kimage *image) 302 { 303 unsigned long start_pgtable; 304 int result; 305 306 /* Calculate the offsets */ 307 start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT; 308 309 /* Setup the identity mapped 64bit page table */ 310 result = init_pgtable(image, start_pgtable); 311 if (result) 312 return result; 313 314 return 0; 315 } 316 317 void machine_kexec_cleanup(struct kimage *image) 318 { 319 free_transition_pgtable(image); 320 } 321 322 /* 323 * Do not allocate memory (or fail in any way) in machine_kexec(). 324 * We are past the point of no return, committed to rebooting now. 325 */ 326 void machine_kexec(struct kimage *image) 327 { 328 unsigned long page_list[PAGES_NR]; 329 void *control_page; 330 int save_ftrace_enabled; 331 332 #ifdef CONFIG_KEXEC_JUMP 333 if (image->preserve_context) 334 save_processor_state(); 335 #endif 336 337 save_ftrace_enabled = __ftrace_enabled_save(); 338 339 /* Interrupts aren't acceptable while we reboot */ 340 local_irq_disable(); 341 hw_breakpoint_disable(); 342 343 if (image->preserve_context) { 344 #ifdef CONFIG_X86_IO_APIC 345 /* 346 * We need to put APICs in legacy mode so that we can 347 * get timer interrupts in second kernel. kexec/kdump 348 * paths already have calls to restore_boot_irq_mode() 349 * in one form or other. kexec jump path also need one. 350 */ 351 clear_IO_APIC(); 352 restore_boot_irq_mode(); 353 #endif 354 } 355 356 control_page = page_address(image->control_code_page) + PAGE_SIZE; 357 memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE); 358 359 page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page); 360 page_list[VA_CONTROL_PAGE] = (unsigned long)control_page; 361 page_list[PA_TABLE_PAGE] = 362 (unsigned long)__pa(page_address(image->control_code_page)); 363 364 if (image->type == KEXEC_TYPE_DEFAULT) 365 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) 366 << PAGE_SHIFT); 367 368 /* 369 * The segment registers are funny things, they have both a 370 * visible and an invisible part. Whenever the visible part is 371 * set to a specific selector, the invisible part is loaded 372 * with from a table in memory. At no other time is the 373 * descriptor table in memory accessed. 374 * 375 * I take advantage of this here by force loading the 376 * segments, before I zap the gdt with an invalid value. 377 */ 378 load_segments(); 379 /* 380 * The gdt & idt are now invalid. 381 * If you want to load them you must set up your own idt & gdt. 382 */ 383 set_gdt(phys_to_virt(0), 0); 384 set_idt(phys_to_virt(0), 0); 385 386 /* now call it */ 387 image->start = relocate_kernel((unsigned long)image->head, 388 (unsigned long)page_list, 389 image->start, 390 image->preserve_context, 391 sme_active()); 392 393 #ifdef CONFIG_KEXEC_JUMP 394 if (image->preserve_context) 395 restore_processor_state(); 396 #endif 397 398 __ftrace_enabled_restore(save_ftrace_enabled); 399 } 400 401 void arch_crash_save_vmcoreinfo(void) 402 { 403 u64 sme_mask = sme_me_mask; 404 405 VMCOREINFO_NUMBER(phys_base); 406 VMCOREINFO_SYMBOL(init_top_pgt); 407 vmcoreinfo_append_str("NUMBER(pgtable_l5_enabled)=%d\n", 408 pgtable_l5_enabled()); 409 410 #ifdef CONFIG_NUMA 411 VMCOREINFO_SYMBOL(node_data); 412 VMCOREINFO_LENGTH(node_data, MAX_NUMNODES); 413 #endif 414 vmcoreinfo_append_str("KERNELOFFSET=%lx\n", 415 kaslr_offset()); 416 VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE); 417 VMCOREINFO_NUMBER(sme_mask); 418 } 419 420 /* arch-dependent functionality related to kexec file-based syscall */ 421 422 #ifdef CONFIG_KEXEC_FILE 423 void *arch_kexec_kernel_image_load(struct kimage *image) 424 { 425 vfree(image->arch.elf_headers); 426 image->arch.elf_headers = NULL; 427 428 if (!image->fops || !image->fops->load) 429 return ERR_PTR(-ENOEXEC); 430 431 return image->fops->load(image, image->kernel_buf, 432 image->kernel_buf_len, image->initrd_buf, 433 image->initrd_buf_len, image->cmdline_buf, 434 image->cmdline_buf_len); 435 } 436 437 /* 438 * Apply purgatory relocations. 439 * 440 * @pi: Purgatory to be relocated. 441 * @section: Section relocations applying to. 442 * @relsec: Section containing RELAs. 443 * @symtabsec: Corresponding symtab. 444 * 445 * TODO: Some of the code belongs to generic code. Move that in kexec.c. 446 */ 447 int arch_kexec_apply_relocations_add(struct purgatory_info *pi, 448 Elf_Shdr *section, const Elf_Shdr *relsec, 449 const Elf_Shdr *symtabsec) 450 { 451 unsigned int i; 452 Elf64_Rela *rel; 453 Elf64_Sym *sym; 454 void *location; 455 unsigned long address, sec_base, value; 456 const char *strtab, *name, *shstrtab; 457 const Elf_Shdr *sechdrs; 458 459 /* String & section header string table */ 460 sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff; 461 strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset; 462 shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset; 463 464 rel = (void *)pi->ehdr + relsec->sh_offset; 465 466 pr_debug("Applying relocate section %s to %u\n", 467 shstrtab + relsec->sh_name, relsec->sh_info); 468 469 for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) { 470 471 /* 472 * rel[i].r_offset contains byte offset from beginning 473 * of section to the storage unit affected. 474 * 475 * This is location to update. This is temporary buffer 476 * where section is currently loaded. This will finally be 477 * loaded to a different address later, pointed to by 478 * ->sh_addr. kexec takes care of moving it 479 * (kexec_load_segment()). 480 */ 481 location = pi->purgatory_buf; 482 location += section->sh_offset; 483 location += rel[i].r_offset; 484 485 /* Final address of the location */ 486 address = section->sh_addr + rel[i].r_offset; 487 488 /* 489 * rel[i].r_info contains information about symbol table index 490 * w.r.t which relocation must be made and type of relocation 491 * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get 492 * these respectively. 493 */ 494 sym = (void *)pi->ehdr + symtabsec->sh_offset; 495 sym += ELF64_R_SYM(rel[i].r_info); 496 497 if (sym->st_name) 498 name = strtab + sym->st_name; 499 else 500 name = shstrtab + sechdrs[sym->st_shndx].sh_name; 501 502 pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n", 503 name, sym->st_info, sym->st_shndx, sym->st_value, 504 sym->st_size); 505 506 if (sym->st_shndx == SHN_UNDEF) { 507 pr_err("Undefined symbol: %s\n", name); 508 return -ENOEXEC; 509 } 510 511 if (sym->st_shndx == SHN_COMMON) { 512 pr_err("symbol '%s' in common section\n", name); 513 return -ENOEXEC; 514 } 515 516 if (sym->st_shndx == SHN_ABS) 517 sec_base = 0; 518 else if (sym->st_shndx >= pi->ehdr->e_shnum) { 519 pr_err("Invalid section %d for symbol %s\n", 520 sym->st_shndx, name); 521 return -ENOEXEC; 522 } else 523 sec_base = pi->sechdrs[sym->st_shndx].sh_addr; 524 525 value = sym->st_value; 526 value += sec_base; 527 value += rel[i].r_addend; 528 529 switch (ELF64_R_TYPE(rel[i].r_info)) { 530 case R_X86_64_NONE: 531 break; 532 case R_X86_64_64: 533 *(u64 *)location = value; 534 break; 535 case R_X86_64_32: 536 *(u32 *)location = value; 537 if (value != *(u32 *)location) 538 goto overflow; 539 break; 540 case R_X86_64_32S: 541 *(s32 *)location = value; 542 if ((s64)value != *(s32 *)location) 543 goto overflow; 544 break; 545 case R_X86_64_PC32: 546 case R_X86_64_PLT32: 547 value -= (u64)address; 548 *(u32 *)location = value; 549 break; 550 default: 551 pr_err("Unknown rela relocation: %llu\n", 552 ELF64_R_TYPE(rel[i].r_info)); 553 return -ENOEXEC; 554 } 555 } 556 return 0; 557 558 overflow: 559 pr_err("Overflow in relocation type %d value 0x%lx\n", 560 (int)ELF64_R_TYPE(rel[i].r_info), value); 561 return -ENOEXEC; 562 } 563 #endif /* CONFIG_KEXEC_FILE */ 564 565 static int 566 kexec_mark_range(unsigned long start, unsigned long end, bool protect) 567 { 568 struct page *page; 569 unsigned int nr_pages; 570 571 /* 572 * For physical range: [start, end]. We must skip the unassigned 573 * crashk resource with zero-valued "end" member. 574 */ 575 if (!end || start > end) 576 return 0; 577 578 page = pfn_to_page(start >> PAGE_SHIFT); 579 nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1; 580 if (protect) 581 return set_pages_ro(page, nr_pages); 582 else 583 return set_pages_rw(page, nr_pages); 584 } 585 586 static void kexec_mark_crashkres(bool protect) 587 { 588 unsigned long control; 589 590 kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect); 591 592 /* Don't touch the control code page used in crash_kexec().*/ 593 control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page)); 594 /* Control code page is located in the 2nd page. */ 595 kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect); 596 control += KEXEC_CONTROL_PAGE_SIZE; 597 kexec_mark_range(control, crashk_res.end, protect); 598 } 599 600 void arch_kexec_protect_crashkres(void) 601 { 602 kexec_mark_crashkres(true); 603 } 604 605 void arch_kexec_unprotect_crashkres(void) 606 { 607 kexec_mark_crashkres(false); 608 } 609 610 /* 611 * During a traditional boot under SME, SME will encrypt the kernel, 612 * so the SME kexec kernel also needs to be un-encrypted in order to 613 * replicate a normal SME boot. 614 * 615 * During a traditional boot under SEV, the kernel has already been 616 * loaded encrypted, so the SEV kexec kernel needs to be encrypted in 617 * order to replicate a normal SEV boot. 618 */ 619 int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, gfp_t gfp) 620 { 621 if (sev_active()) 622 return 0; 623 624 /* 625 * If SME is active we need to be sure that kexec pages are 626 * not encrypted because when we boot to the new kernel the 627 * pages won't be accessed encrypted (initially). 628 */ 629 return set_memory_decrypted((unsigned long)vaddr, pages); 630 } 631 632 void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) 633 { 634 if (sev_active()) 635 return; 636 637 /* 638 * If SME is active we need to reset the pages back to being 639 * an encrypted mapping before freeing them. 640 */ 641 set_memory_encrypted((unsigned long)vaddr, pages); 642 } 643