arch/x86/kernel/crash.c

   1 /*
   2  * Architecture specific (i386/x86_64) functions for kexec based crash dumps.
   3  *
   4  * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   5  *
   6  * Copyright (C) IBM Corporation, 2004. All rights reserved.
   7  * Copyright (C) Red Hat Inc., 2014. All rights reserved.
   8  * Authors:
   9  *      Vivek Goyal <vgoyal@redhat.com>
  10  *
  11  */
  12
  13 #define pr_fmt(fmt)     "kexec: " fmt
  14
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/smp.h>
  18 #include <linux/reboot.h>
  19 #include <linux/kexec.h>
  20 #include <linux/delay.h>
  21 #include <linux/elf.h>
  22 #include <linux/elfcore.h>
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/vmalloc.h>
  26
  27 #include <asm/processor.h>
  28 #include <asm/hardirq.h>
  29 #include <asm/nmi.h>
  30 #include <asm/hw_irq.h>
  31 #include <asm/apic.h>
  32 #include <asm/io_apic.h>
  33 #include <asm/hpet.h>
  34 #include <linux/kdebug.h>
  35 #include <asm/cpu.h>
  36 #include <asm/reboot.h>
  37 #include <asm/virtext.h>
  38 #include <asm/intel_pt.h>
  39
  40 /* Alignment required for elf header segment */
  41 #define ELF_CORE_HEADER_ALIGN   4096
  42
  43 /* This primarily represents number of split ranges due to exclusion */
  44 #define CRASH_MAX_RANGES        16
  45
  46 struct crash_mem_range {
  47         u64 start, end;
  48 };
  49
  50 struct crash_mem {
  51         unsigned int nr_ranges;
  52         struct crash_mem_range ranges[CRASH_MAX_RANGES];
  53 };
  54
  55 /* Misc data about ram ranges needed to prepare elf headers */
  56 struct crash_elf_data {
  57         struct kimage *image;
  58         /*
  59          * Total number of ram ranges we have after various adjustments for
  60          * GART, crash reserved region etc.
  61          */
  62         unsigned int max_nr_ranges;
  63         unsigned long gart_start, gart_end;
  64
  65         /* Pointer to elf header */
  66         void *ehdr;
  67         /* Pointer to next phdr */
  68         void *bufp;
  69         struct crash_mem mem;
  70 };
  71
  72 /* Used while preparing memory map entries for second kernel */
  73 struct crash_memmap_data {
  74         struct boot_params *params;
  75         /* Type of memory */
  76         unsigned int type;
  77 };
  78
  79 /*
  80  * This is used to VMCLEAR all VMCSs loaded on the
  81  * processor. And when loading kvm_intel module, the
  82  * callback function pointer will be assigned.
  83  *
  84  * protected by rcu.
  85  */
  86 crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL;
  87 EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);
  88 unsigned long crash_zero_bytes;
  89
  90 static inline void cpu_crash_vmclear_loaded_vmcss(void)
  91 {
  92         crash_vmclear_fn *do_vmclear_operation = NULL;
  93
  94         rcu_read_lock();
  95         do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
  96         if (do_vmclear_operation)
  97                 do_vmclear_operation();
  98         rcu_read_unlock();
  99 }
 100
 101 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
 102
 103 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
 104 {
 105 #ifdef CONFIG_X86_32
 106         struct pt_regs fixed_regs;
 107
 108         if (!user_mode(regs)) {
 109                 crash_fixup_ss_esp(&fixed_regs, regs);
 110                 regs = &fixed_regs;
 111         }
 112 #endif
 113         crash_save_cpu(regs, cpu);
 114
 115         /*
 116          * VMCLEAR VMCSs loaded on all cpus if needed.
 117          */
 118         cpu_crash_vmclear_loaded_vmcss();
 119
 120         /* Disable VMX or SVM if needed.
 121          *
 122          * We need to disable virtualization on all CPUs.
 123          * Having VMX or SVM enabled on any CPU may break rebooting
 124          * after the kdump kernel has finished its task.
 125          */
 126         cpu_emergency_vmxoff();
 127         cpu_emergency_svm_disable();
 128
 129         /*
 130          * Disable Intel PT to stop its logging
 131          */
 132         cpu_emergency_stop_pt();
 133
 134         disable_local_APIC();
 135 }
 136
 137 static void kdump_nmi_shootdown_cpus(void)
 138 {
 139         nmi_shootdown_cpus(kdump_nmi_callback);
 140
 141         disable_local_APIC();
 142 }
 143
 144 #else
 145 static void kdump_nmi_shootdown_cpus(void)
 146 {
 147         /* There are no cpus to shootdown */
 148 }
 149 #endif
 150
 151 void native_machine_crash_shutdown(struct pt_regs *regs)
 152 {
 153         /* This function is only called after the system
 154          * has panicked or is otherwise in a critical state.
 155          * The minimum amount of code to allow a kexec'd kernel
 156          * to run successfully needs to happen here.
 157          *
 158          * In practice this means shooting down the other cpus in
 159          * an SMP system.
 160          */
 161         /* The kernel is broken so disable interrupts */
 162         local_irq_disable();
 163
 164         kdump_nmi_shootdown_cpus();
 165
 166         /*
 167          * VMCLEAR VMCSs loaded on this cpu if needed.
 168          */
 169         cpu_crash_vmclear_loaded_vmcss();
 170
 171         /* Booting kdump kernel with VMX or SVM enabled won't work,
 172          * because (among other limitations) we can't disable paging
 173          * with the virt flags.
 174          */
 175         cpu_emergency_vmxoff();
 176         cpu_emergency_svm_disable();
 177
 178         /*
 179          * Disable Intel PT to stop its logging
 180          */
 181         cpu_emergency_stop_pt();
 182
 183 #ifdef CONFIG_X86_IO_APIC
 184         /* Prevent crash_kexec() from deadlocking on ioapic_lock. */
 185         ioapic_zap_locks();
 186         disable_IO_APIC();
 187 #endif
 188         lapic_shutdown();
 189 #ifdef CONFIG_HPET_TIMER
 190         hpet_disable();
 191 #endif
 192         crash_save_cpu(regs, safe_smp_processor_id());
 193 }
 194
 195 #ifdef CONFIG_KEXEC_FILE
 196 static int get_nr_ram_ranges_callback(u64 start, u64 end, void *arg)
 197 {
 198         unsigned int *nr_ranges = arg;
 199
 200         (*nr_ranges)++;
 201         return 0;
 202 }
 203
 204 static int get_gart_ranges_callback(u64 start, u64 end, void *arg)
 205 {
 206         struct crash_elf_data *ced = arg;
 207
 208         ced->gart_start = start;
 209         ced->gart_end = end;
 210
 211         /* Not expecting more than 1 gart aperture */
 212         return 1;
 213 }
 214
 215
 216 /* Gather all the required information to prepare elf headers for ram regions */
 217 static void fill_up_crash_elf_data(struct crash_elf_data *ced,
 218                                    struct kimage *image)
 219 {
 220         unsigned int nr_ranges = 0;
 221
 222         ced->image = image;
 223
 224         walk_system_ram_res(0, -1, &nr_ranges,
 225                                 get_nr_ram_ranges_callback);
 226
 227         ced->max_nr_ranges = nr_ranges;
 228
 229         /*
 230          * We don't create ELF headers for GART aperture as an attempt
 231          * to dump this memory in second kernel leads to hang/crash.
 232          * If gart aperture is present, one needs to exclude that region
 233          * and that could lead to need of extra phdr.
 234          */
 235         walk_iomem_res("GART", IORESOURCE_MEM, 0, -1,
 236                                 ced, get_gart_ranges_callback);
 237
 238         /*
 239          * If we have gart region, excluding that could potentially split
 240          * a memory range, resulting in extra header. Account for  that.
 241          */
 242         if (ced->gart_end)
 243                 ced->max_nr_ranges++;
 244
 245         /* Exclusion of crash region could split memory ranges */
 246         ced->max_nr_ranges++;
 247
 248         /* If crashk_low_res is not 0, another range split possible */
 249         if (crashk_low_res.end)
 250                 ced->max_nr_ranges++;
 251 }
 252
 253 static int exclude_mem_range(struct crash_mem *mem,
 254                 unsigned long long mstart, unsigned long long mend)
 255 {
 256         int i, j;
 257         unsigned long long start, end;
 258         struct crash_mem_range temp_range = {0, 0};
 259
 260         for (i = 0; i < mem->nr_ranges; i++) {
 261                 start = mem->ranges[i].start;
 262                 end = mem->ranges[i].end;
 263
 264                 if (mstart > end || mend < start)
 265                         continue;
 266
 267                 /* Truncate any area outside of range */
 268                 if (mstart < start)
 269                         mstart = start;
 270                 if (mend > end)
 271                         mend = end;
 272
 273                 /* Found completely overlapping range */
 274                 if (mstart == start && mend == end) {
 275                         mem->ranges[i].start = 0;
 276                         mem->ranges[i].end = 0;
 277                         if (i < mem->nr_ranges - 1) {
 278                                 /* Shift rest of the ranges to left */
 279                                 for (j = i; j < mem->nr_ranges - 1; j++) {
 280                                         mem->ranges[j].start =
 281                                                 mem->ranges[j+1].start;
 282                                         mem->ranges[j].end =
 283                                                         mem->ranges[j+1].end;
 284                                 }
 285                         }
 286                         mem->nr_ranges--;
 287                         return 0;
 288                 }
 289
 290                 if (mstart > start && mend < end) {
 291                         /* Split original range */
 292                         mem->ranges[i].end = mstart - 1;
 293                         temp_range.start = mend + 1;
 294                         temp_range.end = end;
 295                 } else if (mstart != start)
 296                         mem->ranges[i].end = mstart - 1;
 297                 else
 298                         mem->ranges[i].start = mend + 1;
 299                 break;
 300         }
 301
 302         /* If a split happend, add the split to array */
 303         if (!temp_range.end)
 304                 return 0;
 305
 306         /* Split happened */
 307         if (i == CRASH_MAX_RANGES - 1) {
 308                 pr_err("Too many crash ranges after split\n");
 309                 return -ENOMEM;
 310         }
 311
 312         /* Location where new range should go */
 313         j = i + 1;
 314         if (j < mem->nr_ranges) {
 315                 /* Move over all ranges one slot towards the end */
 316                 for (i = mem->nr_ranges - 1; i >= j; i--)
 317                         mem->ranges[i + 1] = mem->ranges[i];
 318         }
 319
 320         mem->ranges[j].start = temp_range.start;
 321         mem->ranges[j].end = temp_range.end;
 322         mem->nr_ranges++;
 323         return 0;
 324 }
 325
 326 /*
 327  * Look for any unwanted ranges between mstart, mend and remove them. This
 328  * might lead to split and split ranges are put in ced->mem.ranges[] array
 329  */
 330 static int elf_header_exclude_ranges(struct crash_elf_data *ced,
 331                 unsigned long long mstart, unsigned long long mend)
 332 {
 333         struct crash_mem *cmem = &ced->mem;
 334         int ret = 0;
 335
 336         memset(cmem->ranges, 0, sizeof(cmem->ranges));
 337
 338         cmem->ranges[0].start = mstart;
 339         cmem->ranges[0].end = mend;
 340         cmem->nr_ranges = 1;
 341
 342         /* Exclude crashkernel region */
 343         ret = exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
 344         if (ret)
 345                 return ret;
 346
 347         if (crashk_low_res.end) {
 348                 ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
 349                 if (ret)
 350                         return ret;
 351         }
 352
 353         /* Exclude GART region */
 354         if (ced->gart_end) {
 355                 ret = exclude_mem_range(cmem, ced->gart_start, ced->gart_end);
 356                 if (ret)
 357                         return ret;
 358         }
 359
 360         return ret;
 361 }
 362
 363 static int prepare_elf64_ram_headers_callback(u64 start, u64 end, void *arg)
 364 {
 365         struct crash_elf_data *ced = arg;
 366         Elf64_Ehdr *ehdr;
 367         Elf64_Phdr *phdr;
 368         unsigned long mstart, mend;
 369         struct kimage *image = ced->image;
 370         struct crash_mem *cmem;
 371         int ret, i;
 372
 373         ehdr = ced->ehdr;
 374
 375         /* Exclude unwanted mem ranges */
 376         ret = elf_header_exclude_ranges(ced, start, end);
 377         if (ret)
 378                 return ret;
 379
 380         /* Go through all the ranges in ced->mem.ranges[] and prepare phdr */
 381         cmem = &ced->mem;
 382
 383         for (i = 0; i < cmem->nr_ranges; i++) {
 384                 mstart = cmem->ranges[i].start;
 385                 mend = cmem->ranges[i].end;
 386
 387                 phdr = ced->bufp;
 388                 ced->bufp += sizeof(Elf64_Phdr);
 389
 390                 phdr->p_type = PT_LOAD;
 391                 phdr->p_flags = PF_R|PF_W|PF_X;
 392                 phdr->p_offset  = mstart;
 393
 394                 /*
 395                  * If a range matches backup region, adjust offset to backup
 396                  * segment.
 397                  */
 398                 if (mstart == image->arch.backup_src_start &&
 399                     (mend - mstart + 1) == image->arch.backup_src_sz)
 400                         phdr->p_offset = image->arch.backup_load_addr;
 401
 402                 phdr->p_paddr = mstart;
 403                 phdr->p_vaddr = (unsigned long long) __va(mstart);
 404                 phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
 405                 phdr->p_align = 0;
 406                 ehdr->e_phnum++;
 407                 pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
 408                         phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
 409                         ehdr->e_phnum, phdr->p_offset);
 410         }
 411
 412         return ret;
 413 }
 414
 415 static int prepare_elf64_headers(struct crash_elf_data *ced,
 416                 void **addr, unsigned long *sz)
 417 {
 418         Elf64_Ehdr *ehdr;
 419         Elf64_Phdr *phdr;
 420         unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
 421         unsigned char *buf, *bufp;
 422         unsigned int cpu;
 423         unsigned long long notes_addr;
 424         int ret;
 425
 426         /* extra phdr for vmcoreinfo elf note */
 427         nr_phdr = nr_cpus + 1;
 428         nr_phdr += ced->max_nr_ranges;
 429
 430         /*
 431          * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
 432          * area on x86_64 (ffffffff80000000 - ffffffffa0000000).
 433          * I think this is required by tools like gdb. So same physical
 434          * memory will be mapped in two elf headers. One will contain kernel
 435          * text virtual addresses and other will have __va(physical) addresses.
 436          */
 437
 438         nr_phdr++;
 439         elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
 440         elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
 441
 442         buf = vzalloc(elf_sz);
 443         if (!buf)
 444                 return -ENOMEM;
 445
 446         bufp = buf;
 447         ehdr = (Elf64_Ehdr *)bufp;
 448         bufp += sizeof(Elf64_Ehdr);
 449         memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
 450         ehdr->e_ident[EI_CLASS] = ELFCLASS64;
 451         ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
 452         ehdr->e_ident[EI_VERSION] = EV_CURRENT;
 453         ehdr->e_ident[EI_OSABI] = ELF_OSABI;
 454         memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
 455         ehdr->e_type = ET_CORE;
 456         ehdr->e_machine = ELF_ARCH;
 457         ehdr->e_version = EV_CURRENT;
 458         ehdr->e_phoff = sizeof(Elf64_Ehdr);
 459         ehdr->e_ehsize = sizeof(Elf64_Ehdr);
 460         ehdr->e_phentsize = sizeof(Elf64_Phdr);
 461
 462         /* Prepare one phdr of type PT_NOTE for each present cpu */
 463         for_each_present_cpu(cpu) {
 464                 phdr = (Elf64_Phdr *)bufp;
 465                 bufp += sizeof(Elf64_Phdr);
 466                 phdr->p_type = PT_NOTE;
 467                 notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
 468                 phdr->p_offset = phdr->p_paddr = notes_addr;
 469                 phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
 470                 (ehdr->e_phnum)++;
 471         }
 472
 473         /* Prepare one PT_NOTE header for vmcoreinfo */
 474         phdr = (Elf64_Phdr *)bufp;
 475         bufp += sizeof(Elf64_Phdr);
 476         phdr->p_type = PT_NOTE;
 477         phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
 478         phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note);
 479         (ehdr->e_phnum)++;
 480
 481 #ifdef CONFIG_X86_64
 482         /* Prepare PT_LOAD type program header for kernel text region */
 483         phdr = (Elf64_Phdr *)bufp;
 484         bufp += sizeof(Elf64_Phdr);
 485         phdr->p_type = PT_LOAD;
 486         phdr->p_flags = PF_R|PF_W|PF_X;
 487         phdr->p_vaddr = (Elf64_Addr)_text;
 488         phdr->p_filesz = phdr->p_memsz = _end - _text;
 489         phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
 490         (ehdr->e_phnum)++;
 491 #endif
 492
 493         /* Prepare PT_LOAD headers for system ram chunks. */
 494         ced->ehdr = ehdr;
 495         ced->bufp = bufp;
 496         ret = walk_system_ram_res(0, -1, ced,
 497                         prepare_elf64_ram_headers_callback);
 498         if (ret < 0)
 499                 return ret;
 500
 501         *addr = buf;
 502         *sz = elf_sz;
 503         return 0;
 504 }
 505
 506 /* Prepare elf headers. Return addr and size */
 507 static int prepare_elf_headers(struct kimage *image, void **addr,
 508                                         unsigned long *sz)
 509 {
 510         struct crash_elf_data *ced;
 511         int ret;
 512
 513         ced = kzalloc(sizeof(*ced), GFP_KERNEL);
 514         if (!ced)
 515                 return -ENOMEM;
 516
 517         fill_up_crash_elf_data(ced, image);
 518
 519         /* By default prepare 64bit headers */
 520         ret =  prepare_elf64_headers(ced, addr, sz);
 521         kfree(ced);
 522         return ret;
 523 }
 524
 525 static int add_e820_entry(struct boot_params *params, struct e820entry *entry)
 526 {
 527         unsigned int nr_e820_entries;
 528
 529         nr_e820_entries = params->e820_entries;
 530         if (nr_e820_entries >= E820MAX)
 531                 return 1;
 532
 533         memcpy(&params->e820_map[nr_e820_entries], entry,
 534                         sizeof(struct e820entry));
 535         params->e820_entries++;
 536         return 0;
 537 }
 538
 539 static int memmap_entry_callback(u64 start, u64 end, void *arg)
 540 {
 541         struct crash_memmap_data *cmd = arg;
 542         struct boot_params *params = cmd->params;
 543         struct e820entry ei;
 544
 545         ei.addr = start;
 546         ei.size = end - start + 1;
 547         ei.type = cmd->type;
 548         add_e820_entry(params, &ei);
 549
 550         return 0;
 551 }
 552
 553 static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
 554                                  unsigned long long mstart,
 555                                  unsigned long long mend)
 556 {
 557         unsigned long start, end;
 558         int ret = 0;
 559
 560         cmem->ranges[0].start = mstart;
 561         cmem->ranges[0].end = mend;
 562         cmem->nr_ranges = 1;
 563
 564         /* Exclude Backup region */
 565         start = image->arch.backup_load_addr;
 566         end = start + image->arch.backup_src_sz - 1;
 567         ret = exclude_mem_range(cmem, start, end);
 568         if (ret)
 569                 return ret;
 570
 571         /* Exclude elf header region */
 572         start = image->arch.elf_load_addr;
 573         end = start + image->arch.elf_headers_sz - 1;
 574         return exclude_mem_range(cmem, start, end);
 575 }
 576
 577 /* Prepare memory map for crash dump kernel */
 578 int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
 579 {
 580         int i, ret = 0;
 581         unsigned long flags;
 582         struct e820entry ei;
 583         struct crash_memmap_data cmd;
 584         struct crash_mem *cmem;
 585
 586         cmem = vzalloc(sizeof(struct crash_mem));
 587         if (!cmem)
 588                 return -ENOMEM;
 589
 590         memset(&cmd, 0, sizeof(struct crash_memmap_data));
 591         cmd.params = params;
 592
 593         /* Add first 640K segment */
 594         ei.addr = image->arch.backup_src_start;
 595         ei.size = image->arch.backup_src_sz;
 596         ei.type = E820_RAM;
 597         add_e820_entry(params, &ei);
 598
 599         /* Add ACPI tables */
 600         cmd.type = E820_ACPI;
 601         flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 602         walk_iomem_res("ACPI Tables", flags, 0, -1, &cmd,
 603                        memmap_entry_callback);
 604
 605         /* Add ACPI Non-volatile Storage */
 606         cmd.type = E820_NVS;
 607         walk_iomem_res("ACPI Non-volatile Storage", flags, 0, -1, &cmd,
 608                         memmap_entry_callback);
 609
 610         /* Add crashk_low_res region */
 611         if (crashk_low_res.end) {
 612                 ei.addr = crashk_low_res.start;
 613                 ei.size = crashk_low_res.end - crashk_low_res.start + 1;
 614                 ei.type = E820_RAM;
 615                 add_e820_entry(params, &ei);
 616         }
 617
 618         /* Exclude some ranges from crashk_res and add rest to memmap */
 619         ret = memmap_exclude_ranges(image, cmem, crashk_res.start,
 620                                                 crashk_res.end);
 621         if (ret)
 622                 goto out;
 623
 624         for (i = 0; i < cmem->nr_ranges; i++) {
 625                 ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
 626
 627                 /* If entry is less than a page, skip it */
 628                 if (ei.size < PAGE_SIZE)
 629                         continue;
 630                 ei.addr = cmem->ranges[i].start;
 631                 ei.type = E820_RAM;
 632                 add_e820_entry(params, &ei);
 633         }
 634
 635 out:
 636         vfree(cmem);
 637         return ret;
 638 }
 639
 640 static int determine_backup_region(u64 start, u64 end, void *arg)
 641 {
 642         struct kimage *image = arg;
 643
 644         image->arch.backup_src_start = start;
 645         image->arch.backup_src_sz = end - start + 1;
 646
 647         /* Expecting only one range for backup region */
 648         return 1;
 649 }
 650
 651 int crash_load_segments(struct kimage *image)
 652 {
 653         unsigned long src_start, src_sz, elf_sz;
 654         void *elf_addr;
 655         int ret;
 656
 657         /*
 658          * Determine and load a segment for backup area. First 640K RAM
 659          * region is backup source
 660          */
 661
 662         ret = walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,
 663                                 image, determine_backup_region);
 664
 665         /* Zero or postive return values are ok */
 666         if (ret < 0)
 667                 return ret;
 668
 669         src_start = image->arch.backup_src_start;
 670         src_sz = image->arch.backup_src_sz;
 671
 672         /* Add backup segment. */
 673         if (src_sz) {
 674                 /*
 675                  * Ideally there is no source for backup segment. This is
 676                  * copied in purgatory after crash. Just add a zero filled
 677                  * segment for now to make sure checksum logic works fine.
 678                  */
 679                 ret = kexec_add_buffer(image, (char *)&crash_zero_bytes,
 680                                        sizeof(crash_zero_bytes), src_sz,
 681                                        PAGE_SIZE, 0, -1, 0,
 682                                        &image->arch.backup_load_addr);
 683                 if (ret)
 684                         return ret;
 685                 pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",
 686                          image->arch.backup_load_addr, src_start, src_sz);
 687         }
 688
 689         /* Prepare elf headers and add a segment */
 690         ret = prepare_elf_headers(image, &elf_addr, &elf_sz);
 691         if (ret)
 692                 return ret;
 693
 694         image->arch.elf_headers = elf_addr;
 695         image->arch.elf_headers_sz = elf_sz;
 696
 697         ret = kexec_add_buffer(image, (char *)elf_addr, elf_sz, elf_sz,
 698                         ELF_CORE_HEADER_ALIGN, 0, -1, 0,
 699                         &image->arch.elf_load_addr);
 700         if (ret) {
 701                 vfree((void *)image->arch.elf_headers);
 702                 return ret;
 703         }
 704         pr_debug("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 705                  image->arch.elf_load_addr, elf_sz, elf_sz);
 706
 707         return ret;
 708 }
 709 #endif /* CONFIG_KEXEC_FILE */