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linux/arch/x86/purgatory/setup-x86_64.S

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purgatory: core purgatory functionality Create a stand alone relocatable object purgatory which runs between two kernels. This name, concept and some code has been taken from kexec-tools. Idea is that this code runs after a crash and it runs in minimal environment. So keep it separate from rest of the kernel and in long term we will have to practically do no maintenance of this code. This code also has the logic to do verify sha256 hashes of various segments which have been loaded into memory. So first we verify that the kernel we are jumping to is fine and has not been corrupted and make progress only if checsums are verified. This code also takes care of copying some memory contents to backup region. [sfr@canb.auug.org.au: run host built programs from objtree] Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Cc: Borislav Petkov <bp@suse.de> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Eric Biederman <ebiederm@xmission.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Dave Young <dyoung@redhat.com> Cc: WANG Chao <chaowang@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-08 21:26:02 +00:00
/*
* purgatory: setup code
*
* Copyright (C) 2003,2004 Eric Biederman (ebiederm@xmission.com)
* Copyright (C) 2014 Red Hat Inc.
*
* This code has been taken from kexec-tools.
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
kexec, x86/purgatory: Unbreak it and clean it up The purgatory code defines global variables which are referenced via a symbol lookup in the kexec code (core and arch). A recent commit addressing sparse warnings made these static and thereby broke kexec_file. Why did this happen? Simply because the whole machinery is undocumented and lacks any form of forward declarations. The variable names are unspecific and lack a prefix, so adding forward declarations creates shadow variables in the core code. Aside of that the code relies on magic constants and duplicate struct definitions with no way to ensure that these things stay in sync. The section placement of the purgatory variables happened by chance and not by design. Unbreak kexec and cleanup the mess: - Add proper forward declarations and document the usage - Use common struct definition - Use the proper common defines instead of magic constants - Add a purgatory_ prefix to have a proper name space - Use ARRAY_SIZE() instead of a homebrewn reimplementation - Add proper sections to the purgatory variables [ From Mike ] Fixes: 72042a8c7b01 ("x86/purgatory: Make functions and variables static") Reported-by: Mike Galbraith <<efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Nicholas Mc Guire <der.herr@hofr.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Tobin C. Harding" <me@tobin.cc> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1703101315140.3681@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-10 12:17:18 +00:00
#include <asm/purgatory.h>
purgatory: core purgatory functionality Create a stand alone relocatable object purgatory which runs between two kernels. This name, concept and some code has been taken from kexec-tools. Idea is that this code runs after a crash and it runs in minimal environment. So keep it separate from rest of the kernel and in long term we will have to practically do no maintenance of this code. This code also has the logic to do verify sha256 hashes of various segments which have been loaded into memory. So first we verify that the kernel we are jumping to is fine and has not been corrupted and make progress only if checsums are verified. This code also takes care of copying some memory contents to backup region. [sfr@canb.auug.org.au: run host built programs from objtree] Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Cc: Borislav Petkov <bp@suse.de> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Eric Biederman <ebiederm@xmission.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Dave Young <dyoung@redhat.com> Cc: WANG Chao <chaowang@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-08 21:26:02 +00:00
.text
.globl purgatory_start
.balign 16
purgatory_start:
.code64
/* Load a gdt so I know what the segment registers are */
lgdt gdt(%rip)
/* load the data segments */
movl $0x18, %eax /* data segment */
movl %eax, %ds
movl %eax, %es
movl %eax, %ss
movl %eax, %fs
movl %eax, %gs
/* Setup a stack */
leaq lstack_end(%rip), %rsp
/* Call the C code */
call purgatory
jmp entry64
.section ".rodata"
.balign 16
gdt: /* 0x00 unusable segment
* 0x08 unused
* so use them as the gdt ptr
*/
.word gdt_end - gdt - 1
.quad gdt
.word 0, 0, 0
/* 0x10 4GB flat code segment */
.word 0xFFFF, 0x0000, 0x9A00, 0x00AF
/* 0x18 4GB flat data segment */
.word 0xFFFF, 0x0000, 0x9200, 0x00CF
gdt_end:
.bss
.balign 4096
lstack:
.skip 4096
lstack_end:
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