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