aboutsummaryrefslogtreecommitdiffstats
path: root/pc-bios/optionrom/pvh.S
blob: e1d7f4a7a7841a4ea6b4517e29f034852a8dccfc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
/*
 * PVH Option ROM
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright Novell Inc, 2009
 *   Authors: Alexander Graf <agraf@suse.de>
 *
 * Copyright (c) 2019 Red Hat Inc.
 *   Authors: Stefano Garzarella <sgarzare@redhat.com>
 */

#include "optionrom.h"

#define BOOT_ROM_PRODUCT "PVH loader"

#define GS_PROT_JUMP		0
#define GS_GDT_DESC		6

#ifdef OPTION_ROM_START
#undef OPTION_ROM_START
#endif
#ifdef OPTION_ROM_END
#undef OPTION_ROM_END
#endif

/*
 * Redefine OPTION_ROM_START and OPTION_ROM_END, because this rom is produced
 * linking multiple objects.
 * signrom.py will add padding.
 */
#define OPTION_ROM_START                                \
    .code16;						\
    .text;						\
	.global 	_start;				\
    _start:;						\
	.short		0xaa55;				\
	.byte		3; /* desired size in 512 units */

#define OPTION_ROM_END					\
    _end:

BOOT_ROM_START

run_pvhboot:

	cli
	cld

	mov		%cs, %eax
	shl		$0x4, %eax

	/* set up a long jump descriptor that is PC relative */

	/* move stack memory to %gs */
	mov		%ss, %ecx
	shl		$0x4, %ecx
	mov		%esp, %ebx
	add		%ebx, %ecx
	sub		$0x20, %ecx
	sub		$0x30, %esp
	shr		$0x4, %ecx
	mov		%cx, %gs

	/* now push the indirect jump descriptor there */
	mov		(prot_jump), %ebx
	add		%eax, %ebx
	movl		%ebx, %gs:GS_PROT_JUMP
	mov		$8, %bx
	movw		%bx, %gs:GS_PROT_JUMP + 4

	/* fix the gdt descriptor to be PC relative */
	movw		(gdt_desc), %bx
	movw		%bx, %gs:GS_GDT_DESC
	movl		(gdt_desc+2), %ebx
	add		%eax, %ebx
	movl		%ebx, %gs:GS_GDT_DESC + 2

	/* initialize HVM memmap table using int 0x15(e820) */

	/* ES = pvh_e820 struct */
	mov 		$pvh_e820, %eax
	shr		$4, %eax
	mov		%ax, %es

	/* start storing memmap table at %es:8 (pvh_e820.table) */
	mov 		$8,%edi
	xor		%ebx, %ebx
	jmp 		memmap_loop

memmap_loop_check:
	/* pvh_e820 can contains up to 128 entries */
	cmp 		$128, %ebx
	je 		memmap_done

memmap_loop:
	/* entry size (hvm_memmap_table_entry) & max buffer size (int15) */
	movl		$24, %ecx
	/* e820 */
	movl		$0x0000e820, %eax
	/* 'SMAP' magic */
	movl		$0x534d4150, %edx
	/* store counter value at %es:0 (pvh_e820.entries) */
	movl 		%ebx, %es:0

	int		$0x15
	/* error or last entry already done? */
	jb		memmap_err

	/* %edi += entry size (hvm_memmap_table_entry) */
	add		$24, %edi

	/* continuation value 0 means last entry */
	test		%ebx, %ebx
	jnz		memmap_loop_check

	/* increase pvh_e820.entries to save the last entry */
	movl 		%es:0, %ebx
	inc 		%ebx

memmap_done:
	movl 		%ebx, %es:0

memmap_err:

	/* load the GDT before going into protected mode */
lgdt:
	data32 lgdt	%gs:GS_GDT_DESC

	/* get us to protected mode now */
	movl		$1, %eax
	movl		%eax, %cr0

	/* the LJMP sets CS for us and gets us to 32-bit */
ljmp:
	data32 ljmp	*%gs:GS_PROT_JUMP

prot_mode:
.code32

	/* initialize all other segments */
	movl		$0x10, %eax
	movl		%eax, %ss
	movl		%eax, %ds
	movl		%eax, %es
	movl		%eax, %fs
	movl		%eax, %gs

	jmp pvh_load_kernel

/* Variables */
.align 4, 0
prot_jump:	.long prot_mode
		.short 8

.align 4, 0
gdt:
	/* 0x00 */
.byte	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

	/*
	 * 0x08: code segment
	 * (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k)
	 */
.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00

	/*
	 * 0x10: data segment
	 * (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k)
	 */
.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00

	/*
	 * 0x18: code segment
	 * (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b)
	 */
.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00

	/*
	 * 0x20: data segment
	 * (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b)
	 */
.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00

gdt_desc:
.short	(5 * 8) - 1
.long	gdt

BOOT_ROM_END