include/linux/crash_dump.h

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