arch/x86/kernel/machine_kexec_64.c

   1 /*
   2  * handle transition of Linux booting another kernel
   3  * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
   4  *
   5  * This source code is licensed under the GNU General Public License,
   6  * Version 2.  See the file COPYING for more details.
   7  */
   8
   9 #define pr_fmt(fmt)     "kexec: " fmt
  10
  11 #include <linux/mm.h>
  12 #include <linux/kexec.h>
  13 #include <linux/string.h>
  14 #include <linux/gfp.h>
  15 #include <linux/reboot.h>
  16 #include <linux/numa.h>
  17 #include <linux/ftrace.h>
  18 #include <linux/io.h>
  19 #include <linux/suspend.h>
  20 #include <linux/vmalloc.h>
  21
  22 #include <asm/init.h>
  23 #include <asm/pgtable.h>
  24 #include <asm/tlbflush.h>
  25 #include <asm/mmu_context.h>
  26 #include <asm/io_apic.h>
  27 #include <asm/debugreg.h>
  28 #include <asm/kexec-bzimage64.h>
  29 #include <asm/setup.h>
  30
  31 #ifdef CONFIG_KEXEC_FILE
  32 static struct kexec_file_ops *kexec_file_loaders[] = {
  33                 &kexec_bzImage64_ops,
  34 };
  35 #endif
  36
  37 static void free_transition_pgtable(struct kimage *image)
  38 {
  39         free_page((unsigned long)image->arch.pud);
  40         free_page((unsigned long)image->arch.pmd);
  41         free_page((unsigned long)image->arch.pte);
  42 }
  43
  44 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
  45 {
  46         pud_t *pud;
  47         pmd_t *pmd;
  48         pte_t *pte;
  49         unsigned long vaddr, paddr;
  50         int result = -ENOMEM;
  51
  52         vaddr = (unsigned long)relocate_kernel;
  53         paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
  54         pgd += pgd_index(vaddr);
  55         if (!pgd_present(*pgd)) {
  56                 pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
  57                 if (!pud)
  58                         goto err;
  59                 image->arch.pud = pud;
  60                 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
  61         }
  62         pud = pud_offset(pgd, vaddr);
  63         if (!pud_present(*pud)) {
  64                 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
  65                 if (!pmd)
  66                         goto err;
  67                 image->arch.pmd = pmd;
  68                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
  69         }
  70         pmd = pmd_offset(pud, vaddr);
  71         if (!pmd_present(*pmd)) {
  72                 pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
  73                 if (!pte)
  74                         goto err;
  75                 image->arch.pte = pte;
  76                 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
  77         }
  78         pte = pte_offset_kernel(pmd, vaddr);
  79         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
  80         return 0;
  81 err:
  82         free_transition_pgtable(image);
  83         return result;
  84 }
  85
  86 static void *alloc_pgt_page(void *data)
  87 {
  88         struct kimage *image = (struct kimage *)data;
  89         struct page *page;
  90         void *p = NULL;
  91
  92         page = kimage_alloc_control_pages(image, 0);
  93         if (page) {
  94                 p = page_address(page);
  95                 clear_page(p);
  96         }
  97
  98         return p;
  99 }
 100
 101 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 102 {
 103         struct x86_mapping_info info = {
 104                 .alloc_pgt_page = alloc_pgt_page,
 105                 .context        = image,
 106                 .pmd_flag       = __PAGE_KERNEL_LARGE_EXEC,
 107         };
 108         unsigned long mstart, mend;
 109         pgd_t *level4p;
 110         int result;
 111         int i;
 112
 113         level4p = (pgd_t *)__va(start_pgtable);
 114         clear_page(level4p);
 115         for (i = 0; i < nr_pfn_mapped; i++) {
 116                 mstart = pfn_mapped[i].start << PAGE_SHIFT;
 117                 mend   = pfn_mapped[i].end << PAGE_SHIFT;
 118
 119                 result = kernel_ident_mapping_init(&info,
 120                                                  level4p, mstart, mend);
 121                 if (result)
 122                         return result;
 123         }
 124
 125         /*
 126          * segments's mem ranges could be outside 0 ~ max_pfn,
 127          * for example when jump back to original kernel from kexeced kernel.
 128          * or first kernel is booted with user mem map, and second kernel
 129          * could be loaded out of that range.
 130          */
 131         for (i = 0; i < image->nr_segments; i++) {
 132                 mstart = image->segment[i].mem;
 133                 mend   = mstart + image->segment[i].memsz;
 134
 135                 result = kernel_ident_mapping_init(&info,
 136                                                  level4p, mstart, mend);
 137
 138                 if (result)
 139                         return result;
 140         }
 141
 142         return init_transition_pgtable(image, level4p);
 143 }
 144
 145 static void set_idt(void *newidt, u16 limit)
 146 {
 147         struct desc_ptr curidt;
 148
 149         /* x86-64 supports unaliged loads & stores */
 150         curidt.size    = limit;
 151         curidt.address = (unsigned long)newidt;
 152
 153         __asm__ __volatile__ (
 154                 "lidtq %0\n"
 155                 : : "m" (curidt)
 156                 );
 157 };
 158
 159
 160 static void set_gdt(void *newgdt, u16 limit)
 161 {
 162         struct desc_ptr curgdt;
 163
 164         /* x86-64 supports unaligned loads & stores */
 165         curgdt.size    = limit;
 166         curgdt.address = (unsigned long)newgdt;
 167
 168         __asm__ __volatile__ (
 169                 "lgdtq %0\n"
 170                 : : "m" (curgdt)
 171                 );
 172 };
 173
 174 static void load_segments(void)
 175 {
 176         __asm__ __volatile__ (
 177                 "\tmovl %0,%%ds\n"
 178                 "\tmovl %0,%%es\n"
 179                 "\tmovl %0,%%ss\n"
 180                 "\tmovl %0,%%fs\n"
 181                 "\tmovl %0,%%gs\n"
 182                 : : "a" (__KERNEL_DS) : "memory"
 183                 );
 184 }
 185
 186 #ifdef CONFIG_KEXEC_FILE
 187 /* Update purgatory as needed after various image segments have been prepared */
 188 static int arch_update_purgatory(struct kimage *image)
 189 {
 190         int ret = 0;
 191
 192         if (!image->file_mode)
 193                 return 0;
 194
 195         /* Setup copying of backup region */
 196         if (image->type == KEXEC_TYPE_CRASH) {
 197                 ret = kexec_purgatory_get_set_symbol(image, "backup_dest",
 198                                 &image->arch.backup_load_addr,
 199                                 sizeof(image->arch.backup_load_addr), 0);
 200                 if (ret)
 201                         return ret;
 202
 203                 ret = kexec_purgatory_get_set_symbol(image, "backup_src",
 204                                 &image->arch.backup_src_start,
 205                                 sizeof(image->arch.backup_src_start), 0);
 206                 if (ret)
 207                         return ret;
 208
 209                 ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
 210                                 &image->arch.backup_src_sz,
 211                                 sizeof(image->arch.backup_src_sz), 0);
 212                 if (ret)
 213                         return ret;
 214         }
 215
 216         return ret;
 217 }
 218 #else /* !CONFIG_KEXEC_FILE */
 219 static inline int arch_update_purgatory(struct kimage *image)
 220 {
 221         return 0;
 222 }
 223 #endif /* CONFIG_KEXEC_FILE */
 224
 225 int machine_kexec_prepare(struct kimage *image)
 226 {
 227         unsigned long start_pgtable;
 228         int result;
 229
 230         /* Calculate the offsets */
 231         start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
 232
 233         /* Setup the identity mapped 64bit page table */
 234         result = init_pgtable(image, start_pgtable);
 235         if (result)
 236                 return result;
 237
 238         /* update purgatory as needed */
 239         result = arch_update_purgatory(image);
 240         if (result)
 241                 return result;
 242
 243         return 0;
 244 }
 245
 246 void machine_kexec_cleanup(struct kimage *image)
 247 {
 248         free_transition_pgtable(image);
 249 }
 250
 251 /*
 252  * Do not allocate memory (or fail in any way) in machine_kexec().
 253  * We are past the point of no return, committed to rebooting now.
 254  */
 255 void machine_kexec(struct kimage *image)
 256 {
 257         unsigned long page_list[PAGES_NR];
 258         void *control_page;
 259         int save_ftrace_enabled;
 260
 261 #ifdef CONFIG_KEXEC_JUMP
 262         if (image->preserve_context)
 263                 save_processor_state();
 264 #endif
 265
 266         save_ftrace_enabled = __ftrace_enabled_save();
 267
 268         /* Interrupts aren't acceptable while we reboot */
 269         local_irq_disable();
 270         hw_breakpoint_disable();
 271
 272         if (image->preserve_context) {
 273 #ifdef CONFIG_X86_IO_APIC
 274                 /*
 275                  * We need to put APICs in legacy mode so that we can
 276                  * get timer interrupts in second kernel. kexec/kdump
 277                  * paths already have calls to disable_IO_APIC() in
 278                  * one form or other. kexec jump path also need
 279                  * one.
 280                  */
 281                 disable_IO_APIC();
 282 #endif
 283         }
 284
 285         control_page = page_address(image->control_code_page) + PAGE_SIZE;
 286         memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 287
 288         page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
 289         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 290         page_list[PA_TABLE_PAGE] =
 291           (unsigned long)__pa(page_address(image->control_code_page));
 292
 293         if (image->type == KEXEC_TYPE_DEFAULT)
 294                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 295                                                 << PAGE_SHIFT);
 296
 297         /*
 298          * The segment registers are funny things, they have both a
 299          * visible and an invisible part.  Whenever the visible part is
 300          * set to a specific selector, the invisible part is loaded
 301          * with from a table in memory.  At no other time is the
 302          * descriptor table in memory accessed.
 303          *
 304          * I take advantage of this here by force loading the
 305          * segments, before I zap the gdt with an invalid value.
 306          */
 307         load_segments();
 308         /*
 309          * The gdt & idt are now invalid.
 310          * If you want to load them you must set up your own idt & gdt.
 311          */
 312         set_gdt(phys_to_virt(0), 0);
 313         set_idt(phys_to_virt(0), 0);
 314
 315         /* now call it */
 316         image->start = relocate_kernel((unsigned long)image->head,
 317                                        (unsigned long)page_list,
 318                                        image->start,
 319                                        image->preserve_context);
 320
 321 #ifdef CONFIG_KEXEC_JUMP
 322         if (image->preserve_context)
 323                 restore_processor_state();
 324 #endif
 325
 326         __ftrace_enabled_restore(save_ftrace_enabled);
 327 }
 328
 329 void arch_crash_save_vmcoreinfo(void)
 330 {
 331         VMCOREINFO_SYMBOL(phys_base);
 332         VMCOREINFO_SYMBOL(init_level4_pgt);
 333
 334 #ifdef CONFIG_NUMA
 335         VMCOREINFO_SYMBOL(node_data);
 336         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 337 #endif
 338         vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
 339                               kaslr_offset());
 340 }
 341
 342 /* arch-dependent functionality related to kexec file-based syscall */
 343
 344 #ifdef CONFIG_KEXEC_FILE
 345 int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
 346                                   unsigned long buf_len)
 347 {
 348         int i, ret = -ENOEXEC;
 349         struct kexec_file_ops *fops;
 350
 351         for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
 352                 fops = kexec_file_loaders[i];
 353                 if (!fops || !fops->probe)
 354                         continue;
 355
 356                 ret = fops->probe(buf, buf_len);
 357                 if (!ret) {
 358                         image->fops = fops;
 359                         return ret;
 360                 }
 361         }
 362
 363         return ret;
 364 }
 365
 366 void *arch_kexec_kernel_image_load(struct kimage *image)
 367 {
 368         vfree(image->arch.elf_headers);
 369         image->arch.elf_headers = NULL;
 370
 371         if (!image->fops || !image->fops->load)
 372                 return ERR_PTR(-ENOEXEC);
 373
 374         return image->fops->load(image, image->kernel_buf,
 375                                  image->kernel_buf_len, image->initrd_buf,
 376                                  image->initrd_buf_len, image->cmdline_buf,
 377                                  image->cmdline_buf_len);
 378 }
 379
 380 int arch_kimage_file_post_load_cleanup(struct kimage *image)
 381 {
 382         if (!image->fops || !image->fops->cleanup)
 383                 return 0;
 384
 385         return image->fops->cleanup(image->image_loader_data);
 386 }
 387
 388 int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
 389                                  unsigned long kernel_len)
 390 {
 391         if (!image->fops || !image->fops->verify_sig) {
 392                 pr_debug("kernel loader does not support signature verification.");
 393                 return -EKEYREJECTED;
 394         }
 395
 396         return image->fops->verify_sig(kernel, kernel_len);
 397 }
 398
 399 /*
 400  * Apply purgatory relocations.
 401  *
 402  * ehdr: Pointer to elf headers
 403  * sechdrs: Pointer to section headers.
 404  * relsec: section index of SHT_RELA section.
 405  *
 406  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
 407  */
 408 int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
 409                                      Elf64_Shdr *sechdrs, unsigned int relsec)
 410 {
 411         unsigned int i;
 412         Elf64_Rela *rel;
 413         Elf64_Sym *sym;
 414         void *location;
 415         Elf64_Shdr *section, *symtabsec;
 416         unsigned long address, sec_base, value;
 417         const char *strtab, *name, *shstrtab;
 418
 419         /*
 420          * ->sh_offset has been modified to keep the pointer to section
 421          * contents in memory
 422          */
 423         rel = (void *)sechdrs[relsec].sh_offset;
 424
 425         /* Section to which relocations apply */
 426         section = &sechdrs[sechdrs[relsec].sh_info];
 427
 428         pr_debug("Applying relocate section %u to %u\n", relsec,
 429                  sechdrs[relsec].sh_info);
 430
 431         /* Associated symbol table */
 432         symtabsec = &sechdrs[sechdrs[relsec].sh_link];
 433
 434         /* String table */
 435         if (symtabsec->sh_link >= ehdr->e_shnum) {
 436                 /* Invalid strtab section number */
 437                 pr_err("Invalid string table section index %d\n",
 438                        symtabsec->sh_link);
 439                 return -ENOEXEC;
 440         }
 441
 442         strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
 443
 444         /* section header string table */
 445         shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
 446
 447         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 448
 449                 /*
 450                  * rel[i].r_offset contains byte offset from beginning
 451                  * of section to the storage unit affected.
 452                  *
 453                  * This is location to update (->sh_offset). This is temporary
 454                  * buffer where section is currently loaded. This will finally
 455                  * be loaded to a different address later, pointed to by
 456                  * ->sh_addr. kexec takes care of moving it
 457                  *  (kexec_load_segment()).
 458                  */
 459                 location = (void *)(section->sh_offset + rel[i].r_offset);
 460
 461                 /* Final address of the location */
 462                 address = section->sh_addr + rel[i].r_offset;
 463
 464                 /*
 465                  * rel[i].r_info contains information about symbol table index
 466                  * w.r.t which relocation must be made and type of relocation
 467                  * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
 468                  * these respectively.
 469                  */
 470                 sym = (Elf64_Sym *)symtabsec->sh_offset +
 471                                 ELF64_R_SYM(rel[i].r_info);
 472
 473                 if (sym->st_name)
 474                         name = strtab + sym->st_name;
 475                 else
 476                         name = shstrtab + sechdrs[sym->st_shndx].sh_name;
 477
 478                 pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
 479                          name, sym->st_info, sym->st_shndx, sym->st_value,
 480                          sym->st_size);
 481
 482                 if (sym->st_shndx == SHN_UNDEF) {
 483                         pr_err("Undefined symbol: %s\n", name);
 484                         return -ENOEXEC;
 485                 }
 486
 487                 if (sym->st_shndx == SHN_COMMON) {
 488                         pr_err("symbol '%s' in common section\n", name);
 489                         return -ENOEXEC;
 490                 }
 491
 492                 if (sym->st_shndx == SHN_ABS)
 493                         sec_base = 0;
 494                 else if (sym->st_shndx >= ehdr->e_shnum) {
 495                         pr_err("Invalid section %d for symbol %s\n",
 496                                sym->st_shndx, name);
 497                         return -ENOEXEC;
 498                 } else
 499                         sec_base = sechdrs[sym->st_shndx].sh_addr;
 500
 501                 value = sym->st_value;
 502                 value += sec_base;
 503                 value += rel[i].r_addend;
 504
 505                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 506                 case R_X86_64_NONE:
 507                         break;
 508                 case R_X86_64_64:
 509                         *(u64 *)location = value;
 510                         break;
 511                 case R_X86_64_32:
 512                         *(u32 *)location = value;
 513                         if (value != *(u32 *)location)
 514                                 goto overflow;
 515                         break;
 516                 case R_X86_64_32S:
 517                         *(s32 *)location = value;
 518                         if ((s64)value != *(s32 *)location)
 519                                 goto overflow;
 520                         break;
 521                 case R_X86_64_PC32:
 522                         value -= (u64)address;
 523                         *(u32 *)location = value;
 524                         break;
 525                 default:
 526                         pr_err("Unknown rela relocation: %llu\n",
 527                                ELF64_R_TYPE(rel[i].r_info));
 528                         return -ENOEXEC;
 529                 }
 530         }
 531         return 0;
 532
 533 overflow:
 534         pr_err("Overflow in relocation type %d value 0x%lx\n",
 535                (int)ELF64_R_TYPE(rel[i].r_info), value);
 536         return -ENOEXEC;
 537 }
 538 #endif /* CONFIG_KEXEC_FILE */