1 | /* |
2 | * Linux Boot Option ROM for fw_cfg DMA |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify |
5 | * it under the terms of the GNU General Public License as published by |
6 | * the Free Software Foundation; either version 2 of the License, or |
7 | * (at your option) any later version. |
8 | * |
9 | * This program is distributed in the hope that it will be useful, |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
12 | * GNU General Public License for more details. |
13 | * |
14 | * You should have received a copy of the GNU General Public License |
15 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
16 | * |
17 | * Copyright (c) 2015-2016 Red Hat Inc. |
18 | * Authors: |
19 | * Marc MarĂ <marc.mari.barcelo@gmail.com> |
20 | * Richard W.M. Jones <rjones@redhat.com> |
21 | */ |
22 | |
23 | asm( |
24 | ".text\n" |
25 | ".global _start\n" |
26 | "_start:\n" |
27 | " .short 0xaa55\n" |
28 | " .byte 3\n" /* desired size in 512 units; signrom.py adds padding */ |
29 | " .byte 0xcb\n" /* far return without prefix */ |
30 | " .org 0x18\n" |
31 | " .short 0\n" |
32 | " .short _pnph\n" |
33 | "_pnph:\n" |
34 | " .ascii \"$PnP\"\n" |
35 | " .byte 0x01\n" |
36 | " .byte (_pnph_len / 16)\n" |
37 | " .short 0x0000\n" |
38 | " .byte 0x00\n" |
39 | " .byte 0x00\n" |
40 | " .long 0x00000000\n" |
41 | " .short _manufacturer\n" |
42 | " .short _product\n" |
43 | " .long 0x00000000\n" |
44 | " .short 0x0000\n" |
45 | " .short 0x0000\n" |
46 | " .short _bev\n" |
47 | " .short 0x0000\n" |
48 | " .short 0x0000\n" |
49 | " .equ _pnph_len, . - _pnph\n" |
50 | "_manufacturer:\n" |
51 | " .asciz \"QEMU\"\n" |
52 | "_product:\n" |
53 | " .asciz \"Linux loader DMA\"\n" |
54 | " .align 4, 0\n" |
55 | "_bev:\n" |
56 | " cli\n" |
57 | " cld\n" |
58 | " jmp load_kernel\n" |
59 | ); |
60 | |
61 | /* |
62 | * The includes of C headers must be after the asm block to avoid compiler |
63 | * errors. |
64 | */ |
65 | #include <stdint.h> |
66 | #include "optrom.h" |
67 | #include "optrom_fw_cfg.h" |
68 | |
69 | static inline void set_es(void *addr) |
70 | { |
71 | uint32_t seg = (uint32_t)addr >> 4; |
72 | asm("movl %0, %%es" : : "r" (seg)); |
73 | } |
74 | |
75 | static inline uint16_t readw_es(uint16_t offset) |
76 | { |
77 | uint16_t val; |
78 | asm(ADDR32 "movw %%es:(%1), %0" : "=r" (val) : "r" ((uint32_t)offset)); |
79 | barrier(); |
80 | return val; |
81 | } |
82 | |
83 | static inline uint32_t readl_es(uint16_t offset) |
84 | { |
85 | uint32_t val; |
86 | asm(ADDR32 "movl %%es:(%1), %0" : "=r" (val) : "r" ((uint32_t)offset)); |
87 | barrier(); |
88 | return val; |
89 | } |
90 | |
91 | static inline void writel_es(uint16_t offset, uint32_t val) |
92 | { |
93 | barrier(); |
94 | asm(ADDR32 "movl %0, %%es:(%1)" : : "r" (val), "r" ((uint32_t)offset)); |
95 | } |
96 | |
97 | /* Return top of memory using BIOS function E801. */ |
98 | static uint32_t get_e801_addr(void) |
99 | { |
100 | uint16_t ax, bx, cx, dx; |
101 | uint32_t ret; |
102 | |
103 | asm("int $0x15\n" |
104 | : "=a" (ax), "=b" (bx), "=c" (cx), "=d" (dx) |
105 | : "a" (0xe801), "b" (0), "c" (0), "d" (0)); |
106 | |
107 | /* Not SeaBIOS, but in theory a BIOS could return CX=DX=0 in which |
108 | * case we need to use the result from AX & BX instead. |
109 | */ |
110 | if (cx == 0 && dx == 0) { |
111 | cx = ax; |
112 | dx = bx; |
113 | } |
114 | |
115 | if (dx) { |
116 | /* DX = extended memory above 16M, in 64K units. |
117 | * Convert it to bytes and return. |
118 | */ |
119 | ret = ((uint32_t)dx + 256 /* 16M in 64K units */) << 16; |
120 | } else { |
121 | /* This is a fallback path for machines with <= 16MB of RAM, |
122 | * which probably would never be the case, but deal with it |
123 | * anyway. |
124 | * |
125 | * CX = extended memory between 1M and 16M, in kilobytes |
126 | * Convert it to bytes and return. |
127 | */ |
128 | ret = ((uint32_t)cx + 1024 /* 1M in K */) << 10; |
129 | } |
130 | |
131 | return ret; |
132 | } |
133 | |
134 | /* Force the asm name without leading underscore, even on Win32. */ |
135 | extern void load_kernel(void) asm("load_kernel" ); |
136 | |
137 | void load_kernel(void) |
138 | { |
139 | void *setup_addr; |
140 | void *initrd_addr; |
141 | void *kernel_addr; |
142 | void *cmdline_addr; |
143 | uint32_t setup_size; |
144 | uint32_t initrd_size; |
145 | uint32_t kernel_size; |
146 | uint32_t cmdline_size; |
147 | uint32_t initrd_end_page, max_allowed_page; |
148 | uint32_t segment_addr, stack_addr; |
149 | |
150 | bios_cfg_read_entry_dma(&setup_addr, FW_CFG_SETUP_ADDR, 4); |
151 | bios_cfg_read_entry_dma(&setup_size, FW_CFG_SETUP_SIZE, 4); |
152 | bios_cfg_read_entry_dma(setup_addr, FW_CFG_SETUP_DATA, setup_size); |
153 | |
154 | set_es(setup_addr); |
155 | |
156 | /* For protocol < 0x203 we don't have initrd_max ... */ |
157 | if (readw_es(0x206) < 0x203) { |
158 | /* ... so we assume initrd_max = 0x37ffffff. */ |
159 | writel_es(0x22c, 0x37ffffff); |
160 | } |
161 | |
162 | bios_cfg_read_entry_dma(&initrd_addr, FW_CFG_INITRD_ADDR, 4); |
163 | bios_cfg_read_entry_dma(&initrd_size, FW_CFG_INITRD_SIZE, 4); |
164 | |
165 | initrd_end_page = ((uint32_t)(initrd_addr + initrd_size) & -4096); |
166 | max_allowed_page = (readl_es(0x22c) & -4096); |
167 | |
168 | if (initrd_end_page != 0 && max_allowed_page != 0 && |
169 | initrd_end_page != max_allowed_page) { |
170 | /* Initrd at the end of memory. Compute better initrd address |
171 | * based on e801 data |
172 | */ |
173 | initrd_addr = (void *)((get_e801_addr() - initrd_size) & -4096); |
174 | writel_es(0x218, (uint32_t)initrd_addr); |
175 | |
176 | } |
177 | |
178 | bios_cfg_read_entry_dma(initrd_addr, FW_CFG_INITRD_DATA, initrd_size); |
179 | |
180 | bios_cfg_read_entry_dma(&kernel_addr, FW_CFG_KERNEL_ADDR, 4); |
181 | bios_cfg_read_entry_dma(&kernel_size, FW_CFG_KERNEL_SIZE, 4); |
182 | bios_cfg_read_entry_dma(kernel_addr, FW_CFG_KERNEL_DATA, kernel_size); |
183 | |
184 | bios_cfg_read_entry_dma(&cmdline_addr, FW_CFG_CMDLINE_ADDR, 4); |
185 | bios_cfg_read_entry_dma(&cmdline_size, FW_CFG_CMDLINE_SIZE, 4); |
186 | bios_cfg_read_entry_dma(cmdline_addr, FW_CFG_CMDLINE_DATA, cmdline_size); |
187 | |
188 | /* Boot linux */ |
189 | segment_addr = ((uint32_t)setup_addr >> 4); |
190 | stack_addr = (uint32_t)(cmdline_addr - setup_addr - 16); |
191 | |
192 | /* As we are changing critical registers, we cannot leave freedom to the |
193 | * compiler. |
194 | */ |
195 | asm("movw %%ax, %%ds\n" |
196 | "movw %%ax, %%es\n" |
197 | "movw %%ax, %%fs\n" |
198 | "movw %%ax, %%gs\n" |
199 | "movw %%ax, %%ss\n" |
200 | "movl %%ebx, %%esp\n" |
201 | "addw $0x20, %%ax\n" |
202 | "pushw %%ax\n" /* CS */ |
203 | "pushw $0\n" /* IP */ |
204 | /* Clear registers and jump to Linux */ |
205 | "xor %%ebx, %%ebx\n" |
206 | "xor %%ecx, %%ecx\n" |
207 | "xor %%edx, %%edx\n" |
208 | "xor %%edi, %%edi\n" |
209 | "xor %%ebp, %%ebp\n" |
210 | "lretw\n" |
211 | : : "a" (segment_addr), "b" (stack_addr)); |
212 | } |
213 | |