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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/x86/purgatory/setup-x86_64.S
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/* SPDX-License-Identifier: GPL-2.0-only */

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/*

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 * purgatory:  setup code

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 *

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 * Copyright (C) 2003,2004  Eric Biederman ([email protected])

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 * Copyright (C) 2014 Red Hat Inc.

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 *

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 * This code has been taken from kexec-tools.

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 */

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#include <linux/linkage.h>

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#include <asm/purgatory.h>

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	.text

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	.balign 16

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	.code64

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SYM_CODE_START(purgatory_start)

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	/* Load a gdt so I know what the segment registers are */

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	lgdt	gdt(%rip)

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	/* load the data segments */

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	movl	$0x18, %eax	/* data segment */

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	movl	%eax, %ds

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	movl	%eax, %es

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	movl	%eax, %ss

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	movl	%eax, %fs

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	movl	%eax, %gs

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	/* Setup a stack */

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	leaq	lstack_end(%rip), %rsp

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	/* Call the C code */

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	call purgatory

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	jmp	entry64

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SYM_CODE_END(purgatory_start)

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	.section ".rodata"

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	.balign 16

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SYM_DATA_START_LOCAL(gdt)

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	/* 0x00 unusable segment

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	 * 0x08 unused

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	 * so use them as the gdt ptr

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	 */

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	.word	gdt_end - gdt - 1

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	.quad	gdt

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	.word	0, 0, 0

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	/* 0x10 4GB flat code segment */

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	.word	0xFFFF, 0x0000, 0x9A00, 0x00AF

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	/* 0x18 4GB flat data segment */

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	.word	0xFFFF, 0x0000, 0x9200, 0x00CF

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SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)

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	.bss

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	.balign 4096

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SYM_DATA_START_LOCAL(lstack)

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	.skip 4096

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SYM_DATA_END_LABEL(lstack, SYM_L_LOCAL, lstack_end)

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