xref: /illumos-gate/usr/src/boot/i386/libi386/amd64_tramp.S (revision 55fea89dcaa64928bed4327112404dcb3e07b79f)
1/*-
2 * Copyright (c) 2003  Peter Wemm <peter@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD$
27 */
28
29/*
30 * Quick and dirty trampoline to get into 64 bit (long) mode and running
31 * with paging enabled so that we enter the kernel at its linked address.
32 */
33#define MSR_EFER	0xc0000080
34#define EFER_LME	0x00000100
35#define CR4_PAE		0x00000020
36#define CR4_PSE		0x00000010
37#define CR0_PG		0x80000000
38
39/* GRRR. Deal with BTX that links us for a non-zero location */
40#define VPBASE	0xa000
41#define VTOP(x)	((x) + VPBASE)
42
43	.data
44
45	.p2align 12,0x40
46
47	.globl	PT4
48PT4:
49	.space	0x1000
50	.globl	PT3
51PT3:
52	.space	0x1000
53	.globl	PT2
54PT2:
55	.space	0x1000
56
57gdtdesc:
58	.word	gdtend - gdt
59	.long	VTOP(gdt)		# low
60	.long	0			# high
61
62gdt:
63	.long	0			# null descriptor
64	.long	0
65	.long	0x00000000		# %cs
66	.long	0x00209800
67	.long	0x00000000		# %ds
68	.long	0x00008000
69gdtend:
70
71	.text
72	.code32
73
74	.globl	amd64_tramp
75amd64_tramp:
76	/* Be sure that interrupts are disabled */
77	cli
78
79	/* Turn on EFER.LME */
80	movl	$MSR_EFER, %ecx
81	rdmsr
82	orl	$EFER_LME, %eax
83	wrmsr
84
85	/* Turn on PAE */
86	movl	%cr4, %eax
87	orl	$CR4_PAE, %eax
88	movl	%eax, %cr4
89
90	/* Set %cr3 for PT4 */
91	movl	$VTOP(PT4), %eax
92	movl	%eax, %cr3
93
94	/* Turn on paging (implicitly sets EFER.LMA) */
95	movl	%cr0, %eax
96	orl	$CR0_PG, %eax
97	movl	%eax, %cr0
98
99	/* Now we're in compatibility mode. set %cs for long mode */
100	movl	$VTOP(gdtdesc), %eax
101	movl	VTOP(entry_hi), %esi
102	movl	VTOP(entry_lo), %edi
103	lgdt	(%eax)
104	ljmp	$0x8, $VTOP(longmode)
105
106	.code64
107longmode:
108	/* We're still running V=P, jump to entry point */
109	movl	%esi, %eax
110	salq	$32, %rax
111	orq	%rdi, %rax
112	pushq	%rax
113	ret
114