Commit 79e03011 authored by Ian Campbell's avatar Ian Campbell Committed by Andi Kleen
Browse files

[PATCH] i386: Allow i386 crash kernels to handle x86_64 dumps 



The specific case I am encountering is kdump under Xen with a 64 bit
hypervisor and 32 bit kernel/userspace.  The dump created is 64 bit due to
the hypervisor but the dump kernel is 32 bit for maximum compatibility.

It's possibly less likely to be useful in a purely native scenario but I
see no reason to disallow it.

[akpm@linux-foundation.org: build fix]
Signed-off-by: default avatarIan Campbell <ian.campbell@xensource.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Acked-by: default avatarVivek Goyal <vgoyal@in.ibm.com>
Cc: Horms <horms@verge.net.au>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent eab0c72a

fs/proc/vmcore.c

+1 −1
Original line number Diff line number Diff line
@@ -514,7 +514,7 @@ static int __init parse_crash_elf64_headers(void) 
	/* Do some basic Verification. */

	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||

		(ehdr.e_type != ET_CORE) ||

		!elf_check_arch(&ehdr) ||

		!vmcore_elf_check_arch(&ehdr) ||

		ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||

		ehdr.e_ident[EI_VERSION] != EV_CURRENT ||

		ehdr.e_version != EV_CURRENT ||

include/asm-i386/kexec.h

+3 −0
Original line number Diff line number Diff line
@@ -42,6 +42,9 @@ 
/* The native architecture */

#define KEXEC_ARCH KEXEC_ARCH_386



/* We can also handle crash dumps from 64 bit kernel. */

#define vmcore_elf_check_arch_cross(x) ((x)->e_machine == EM_X86_64)



#define MAX_NOTE_BYTES 1024



/* CPU does not save ss and esp on stack if execution is already

include/linux/crash_dump.h

+8 −0
Original line number Diff line number Diff line
@@ -14,5 +14,13 @@ extern ssize_t copy_oldmem_page(unsigned long, char *, size_t, 
extern const struct file_operations proc_vmcore_operations;

extern struct proc_dir_entry *proc_vmcore;



/* Architecture code defines this if there are other possible ELF

 * machine types, e.g. on bi-arch capable hardware. */

#ifndef vmcore_elf_check_arch_cross

#define vmcore_elf_check_arch_cross(x) 0

#endif



#define vmcore_elf_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))



#endif /* CONFIG_CRASH_DUMP */

#endif /* LINUX_CRASHDUMP_H */

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