85a0ee342e
The usage of elfcorehdr_addr has changed recently such that being set to ELFCORE_ADDR_MAX is used by is_kdump_kernel() to indicate if the code is executing in a kernel executed as a crash kernel. However, arch/ia64/kernel/setup.c:reserve_elfcorehdr will rest elfcorehdr_addr to ELFCORE_ADDR_MAX on error, which means any subsequent calls to is_kdump_kernel() will return 0, even though they should return 1. Ok, at this point in time there are no subsequent calls, but I think its fair to say that there is ample scope for error or at the very least confusion. This patch add an extra state, ELFCORE_ADDR_ERR, which indicates that elfcorehdr_addr was passed on the command line, and thus execution is taking place in a crashdump kernel, but vmcore can't be used for some reason. This is tested for using is_vmcore_usable() and set using vmcore_unusable(). A subsequent patch makes use of this new code. To summarise, the states that elfcorehdr_addr can now be in are as follows: ELFCORE_ADDR_MAX: not a crashdump kernel ELFCORE_ADDR_ERR: crashdump kernel but vmcore is unusable any other value: crash dump kernel and vmcore is usable Signed-off-by: Simon Horman <horms@verge.net.au> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
71 lines
2.1 KiB
C
71 lines
2.1 KiB
C
#ifndef LINUX_CRASH_DUMP_H
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#define LINUX_CRASH_DUMP_H
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#ifdef CONFIG_CRASH_DUMP
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#include <linux/kexec.h>
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#include <linux/smp_lock.h>
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#include <linux/device.h>
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#include <linux/proc_fs.h>
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#define ELFCORE_ADDR_MAX (-1ULL)
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#define ELFCORE_ADDR_ERR (-2ULL)
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extern unsigned long long elfcorehdr_addr;
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extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
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unsigned long, int);
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extern const struct file_operations proc_vmcore_operations;
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extern struct proc_dir_entry *proc_vmcore;
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/* Architecture code defines this if there are other possible ELF
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* machine types, e.g. on bi-arch capable hardware. */
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#ifndef vmcore_elf_check_arch_cross
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#define vmcore_elf_check_arch_cross(x) 0
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#endif
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#define vmcore_elf_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
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/*
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* is_kdump_kernel() checks whether this kernel is booting after a panic of
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* previous kernel or not. This is determined by checking if previous kernel
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* has passed the elf core header address on command line.
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*
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* This is not just a test if CONFIG_CRASH_DUMP is enabled or not. It will
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* return 1 if CONFIG_CRASH_DUMP=y and if kernel is booting after a panic of
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* previous kernel.
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*/
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static inline int is_kdump_kernel(void)
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{
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return (elfcorehdr_addr != ELFCORE_ADDR_MAX) ? 1 : 0;
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}
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/* is_vmcore_usable() checks if the kernel is booting after a panic and
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* the vmcore region is usable.
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*
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* This makes use of the fact that due to alignment -2ULL is not
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* a valid pointer, much in the vain of IS_ERR(), except
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* dealing directly with an unsigned long long rather than a pointer.
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*/
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static inline int is_vmcore_usable(void)
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{
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return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0;
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}
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/* vmcore_unusable() marks the vmcore as unusable,
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* without disturbing the logic of is_kdump_kernel()
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*/
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static inline void vmcore_unusable(void)
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{
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if (is_kdump_kernel())
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elfcorehdr_addr = ELFCORE_ADDR_ERR;
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}
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#else /* !CONFIG_CRASH_DUMP */
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static inline int is_kdump_kernel(void) { return 0; }
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#endif /* CONFIG_CRASH_DUMP */
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extern unsigned long saved_max_pfn;
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#endif /* LINUX_CRASHDUMP_H */
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