kernel/crash_dump.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/kernel.h>
   3 #include <linux/crash_dump.h>
   4 #include <linux/init.h>
   5 #include <linux/errno.h>
   6 #include <linux/export.h>
   7
   8 /*
   9  * If we have booted due to a crash, max_pfn will be a very low value. We need
  10  * to know the amount of memory that the previous kernel used.
  11  */
  12 unsigned long saved_max_pfn;
  13
  14 /*
  15  * stores the physical address of elf header of crash image
  16  *
  17  * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
  18  * is_kdump_kernel() to determine if we are booting after a panic. Hence put
  19  * it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
  20  */
  21 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
  22 EXPORT_SYMBOL_GPL(elfcorehdr_addr);
  23
  24 /*
  25  * stores the size of elf header of crash image
  26  */
  27 unsigned long long elfcorehdr_size;
  28
  29 /*
  30  * elfcorehdr= specifies the location of elf core header stored by the crashed
  31  * kernel. This option will be passed by kexec loader to the capture kernel.
  32  *
  33  * Syntax: elfcorehdr=[size[KMG]@]offset[KMG]
  34  */
  35 static int __init setup_elfcorehdr(char *arg)
  36 {
  37         char *end;
  38         if (!arg)
  39                 return -EINVAL;
  40         elfcorehdr_addr = memparse(arg, &end);
  41         if (*end == '@') {
  42                 elfcorehdr_size = elfcorehdr_addr;
  43                 elfcorehdr_addr = memparse(end + 1, &end);
  44         }
  45         return end > arg ? 0 : -EINVAL;
  46 }
  47 early_param("elfcorehdr", setup_elfcorehdr);