1 #ifndef LINUX_CRASH_DUMP_H
2 #define LINUX_CRASH_DUMP_H
3 
4 #ifdef CONFIG_CRASH_DUMP
5 #include <linux/kexec.h>
6 #include <linux/device.h>
7 #include <linux/proc_fs.h>
8 
9 #define ELFCORE_ADDR_MAX	(-1ULL)
10 #define ELFCORE_ADDR_ERR	(-2ULL)
11 
12 extern unsigned long long elfcorehdr_addr;
13 
14 extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
15 						unsigned long, int);
16 
17 /* Architecture code defines this if there are other possible ELF
18  * machine types, e.g. on bi-arch capable hardware. */
19 #ifndef vmcore_elf_check_arch_cross
20 #define vmcore_elf_check_arch_cross(x) 0
21 #endif
22 
23 /*
24  * Architecture code can redefine this if there are any special checks
25  * needed for 64-bit ELF vmcores. In case of 32-bit only architecture,
26  * this can be set to zero.
27  */
28 #ifndef vmcore_elf64_check_arch
29 #define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
30 #endif
31 
32 /*
33  * is_kdump_kernel() checks whether this kernel is booting after a panic of
34  * previous kernel or not. This is determined by checking if previous kernel
35  * has passed the elf core header address on command line.
36  *
37  * This is not just a test if CONFIG_CRASH_DUMP is enabled or not. It will
38  * return 1 if CONFIG_CRASH_DUMP=y and if kernel is booting after a panic of
39  * previous kernel.
40  */
41 
is_kdump_kernel(void)42 static inline int is_kdump_kernel(void)
43 {
44 	return (elfcorehdr_addr != ELFCORE_ADDR_MAX) ? 1 : 0;
45 }
46 
47 /* is_vmcore_usable() checks if the kernel is booting after a panic and
48  * the vmcore region is usable.
49  *
50  * This makes use of the fact that due to alignment -2ULL is not
51  * a valid pointer, much in the vain of IS_ERR(), except
52  * dealing directly with an unsigned long long rather than a pointer.
53  */
54 
is_vmcore_usable(void)55 static inline int is_vmcore_usable(void)
56 {
57 	return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
58 }
59 
60 /* vmcore_unusable() marks the vmcore as unusable,
61  * without disturbing the logic of is_kdump_kernel()
62  */
63 
vmcore_unusable(void)64 static inline void vmcore_unusable(void)
65 {
66 	if (is_kdump_kernel())
67 		elfcorehdr_addr = ELFCORE_ADDR_ERR;
68 }
69 #else /* !CONFIG_CRASH_DUMP */
is_kdump_kernel(void)70 static inline int is_kdump_kernel(void) { return 0; }
71 #endif /* CONFIG_CRASH_DUMP */
72 
73 extern unsigned long saved_max_pfn;
74 #endif /* LINUX_CRASHDUMP_H */
75