LXR linux/include/linux/crash

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef LINUX_CRASH_DUMP_H
   3#define LINUX_CRASH_DUMP_H
   4
   5#include <linux/kexec.h>
   6#include <linux/proc_fs.h>
   7#include <linux/elf.h>
   8#include <linux/pgtable.h>
   9#include <uapi/linux/vmcore.h>
  10
  11/* For IS_ENABLED(CONFIG_CRASH_DUMP) */
  12#define ELFCORE_ADDR_MAX        (-1ULL)
  13#define ELFCORE_ADDR_ERR        (-2ULL)
  14
  15extern unsigned long long elfcorehdr_addr;
  16extern unsigned long long elfcorehdr_size;
  17
  18#ifdef CONFIG_CRASH_DUMP
  19extern int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size);
  20extern void elfcorehdr_free(unsigned long long addr);
  21extern ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos);
  22extern ssize_t elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos);
  23extern int remap_oldmem_pfn_range(struct vm_area_struct *vma,
  24                                  unsigned long from, unsigned long pfn,
  25                                  unsigned long size, pgprot_t prot);
  26
  27extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
  28                                                unsigned long, int);
  29extern ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf,
  30                                          size_t csize, unsigned long offset,
  31                                          int userbuf);
  32
  33void vmcore_cleanup(void);
  34
  35/* Architecture code defines this if there are other possible ELF
  36 * machine types, e.g. on bi-arch capable hardware. */
  37#ifndef vmcore_elf_check_arch_cross
  38#define vmcore_elf_check_arch_cross(x) 0
  39#endif
  40
  41/*
  42 * Architecture code can redefine this if there are any special checks
  43 * needed for 32-bit ELF or 64-bit ELF vmcores.  In case of 32-bit
  44 * only architecture, vmcore_elf64_check_arch can be set to zero.
  45 */
  46#ifndef vmcore_elf32_check_arch
  47#define vmcore_elf32_check_arch(x) elf_check_arch(x)
  48#endif
  49
  50#ifndef vmcore_elf64_check_arch
  51#define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
  52#endif
  53
  54/*
  55 * is_kdump_kernel() checks whether this kernel is booting after a panic of
  56 * previous kernel or not. This is determined by checking if previous kernel
  57 * has passed the elf core header address on command line.
  58 *
  59 * This is not just a test if CONFIG_CRASH_DUMP is enabled or not. It will
  60 * return true if CONFIG_CRASH_DUMP=y and if kernel is booting after a panic
  61 * of previous kernel.
  62 */
  63
  64static inline bool is_kdump_kernel(void)
  65{
  66        return elfcorehdr_addr != ELFCORE_ADDR_MAX;
  67}
  68
  69/* is_vmcore_usable() checks if the kernel is booting after a panic and
  70 * the vmcore region is usable.
  71 *
  72 * This makes use of the fact that due to alignment -2ULL is not
  73 * a valid pointer, much in the vain of IS_ERR(), except
  74 * dealing directly with an unsigned long long rather than a pointer.
  75 */
  76
  77static inline int is_vmcore_usable(void)
  78{
  79        return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
  80}
  81
  82/* vmcore_unusable() marks the vmcore as unusable,
  83 * without disturbing the logic of is_kdump_kernel()
  84 */
  85
  86static inline void vmcore_unusable(void)
  87{
  88        if (is_kdump_kernel())
  89                elfcorehdr_addr = ELFCORE_ADDR_ERR;
  90}
  91
  92/**
  93 * struct vmcore_cb - driver callbacks for /proc/vmcore handling
  94 * @pfn_is_ram: check whether a PFN really is RAM and should be accessed when
  95 *              reading the vmcore. Will return "true" if it is RAM or if the
  96 *              callback cannot tell. If any callback returns "false", it's not
  97 *              RAM and the page must not be accessed; zeroes should be
  98 *              indicated in the vmcore instead. For example, a ballooned page
  99 *              contains no data and reading from such a page will cause high
 100 *              load in the hypervisor.
 101 * @next: List head to manage registered callbacks internally; initialized by
 102 *        register_vmcore_cb().
 103 *
 104 * vmcore callbacks allow drivers managing physical memory ranges to
 105 * coordinate with vmcore handling code, for example, to prevent accessing
 106 * physical memory ranges that should not be accessed when reading the vmcore,
 107 * although included in the vmcore header as memory ranges to dump.
 108 */
 109struct vmcore_cb {
 110        bool (*pfn_is_ram)(struct vmcore_cb *cb, unsigned long pfn);
 111        struct list_head next;
 112};
 113extern void register_vmcore_cb(struct vmcore_cb *cb);
 114extern void unregister_vmcore_cb(struct vmcore_cb *cb);
 115
 116#else /* !CONFIG_CRASH_DUMP */
 117static inline bool is_kdump_kernel(void) { return false; }
 118#endif /* CONFIG_CRASH_DUMP */
 119
 120/* Device Dump information to be filled by drivers */
 121struct vmcoredd_data {
 122        char dump_name[VMCOREDD_MAX_NAME_BYTES]; /* Unique name of the dump */
 123        unsigned int size;                       /* Size of the dump */
 124        /* Driver's registered callback to be invoked to collect dump */
 125        int (*vmcoredd_callback)(struct vmcoredd_data *data, void *buf);
 126};
 127
 128#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
 129int vmcore_add_device_dump(struct vmcoredd_data *data);
 130#else
 131static inline int vmcore_add_device_dump(struct vmcoredd_data *data)
 132{
 133        return -EOPNOTSUPP;
 134}
 135#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
 136
 137#ifdef CONFIG_PROC_VMCORE
 138ssize_t read_from_oldmem(char *buf, size_t count,
 139                         u64 *ppos, int userbuf,
 140                         bool encrypted);
 141#else
 142static inline ssize_t read_from_oldmem(char *buf, size_t count,
 143                                       u64 *ppos, int userbuf,
 144                                       bool encrypted)
 145{
 146        return -EOPNOTSUPP;
 147}
 148#endif /* CONFIG_PROC_VMCORE */
 149
 150#endif /* LINUX_CRASHDUMP_H */
 151