xref: /openbmc/linux/arch/x86/purgatory/entry64.S (revision b16fed65)
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2003,2004  Eric Biederman (ebiederm@xmission.com)
4 * Copyright (C) 2014  Red Hat Inc.
5
6 * Author(s): Vivek Goyal <vgoyal@redhat.com>
7 *
8 * This code has been taken from kexec-tools.
9 */
10
11#include <linux/linkage.h>
12
13	.text
14	.balign 16
15	.code64
16
17SYM_CODE_START(entry64)
18	/* Setup a gdt that should be preserved */
19	lgdt gdt(%rip)
20
21	/* load the data segments */
22	movl    $0x18, %eax     /* data segment */
23	movl    %eax, %ds
24	movl    %eax, %es
25	movl    %eax, %ss
26	movl    %eax, %fs
27	movl    %eax, %gs
28
29	/* Setup new stack */
30	leaq    stack_init(%rip), %rsp
31	pushq   $0x10 /* CS */
32	leaq    new_cs_exit(%rip), %rax
33	pushq   %rax
34	lretq
35new_cs_exit:
36
37	/* Load the registers */
38	movq	rax(%rip), %rax
39	movq	rbx(%rip), %rbx
40	movq	rcx(%rip), %rcx
41	movq	rdx(%rip), %rdx
42	movq	rsi(%rip), %rsi
43	movq	rdi(%rip), %rdi
44	movq    rsp(%rip), %rsp
45	movq	rbp(%rip), %rbp
46	movq	r8(%rip), %r8
47	movq	r9(%rip), %r9
48	movq	r10(%rip), %r10
49	movq	r11(%rip), %r11
50	movq	r12(%rip), %r12
51	movq	r13(%rip), %r13
52	movq	r14(%rip), %r14
53	movq	r15(%rip), %r15
54
55	/* Jump to the new code... */
56	jmpq	*rip(%rip)
57SYM_CODE_END(entry64)
58
59	.section ".rodata"
60	.balign 4
61SYM_DATA_START(entry64_regs)
62rax:	.quad 0x0
63rcx:	.quad 0x0
64rdx:	.quad 0x0
65rbx:	.quad 0x0
66rsp:	.quad 0x0
67rbp:	.quad 0x0
68rsi:	.quad 0x0
69rdi:	.quad 0x0
70r8:	.quad 0x0
71r9:	.quad 0x0
72r10:	.quad 0x0
73r11:	.quad 0x0
74r12:	.quad 0x0
75r13:	.quad 0x0
76r14:	.quad 0x0
77r15:	.quad 0x0
78rip:	.quad 0x0
79SYM_DATA_END(entry64_regs)
80
81	/* GDT */
82	.section ".rodata"
83	.balign 16
84SYM_DATA_START_LOCAL(gdt)
85	/*
86	 * 0x00 unusable segment
87	 * 0x08 unused
88	 * so use them as gdt ptr
89	 */
90	.word gdt_end - gdt - 1
91	.quad gdt
92	.word 0, 0, 0
93
94	/* 0x10 4GB flat code segment */
95	.word 0xFFFF, 0x0000, 0x9A00, 0x00AF
96
97	/* 0x18 4GB flat data segment */
98	.word 0xFFFF, 0x0000, 0x9200, 0x00CF
99SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)
100
101SYM_DATA_START_LOCAL(stack)
102	.quad   0, 0
103SYM_DATA_END_LABEL(stack, SYM_L_LOCAL, stack_init)
104