1 /* ----------------------------------------------------------------------- *
2 *
3 * Copyright 2007-2009 H. Peter Anvin - All Rights Reserved
4 * Copyright 2009 H. Peter Anvin - All Rights Reserved
5 *
6 * Permission is hereby granted, free of charge, to any person
7 * obtaining a copy of this software and associated documentation
8 * files (the "Software"), to deal in the Software without
9 * restriction, including without limitation the rights to use,
10 * copy, modify, merge, publish, distribute, sublicense, and/or
11 * sell copies of the Software, and to permit persons to whom
12 * the Software is furnished to do so, subject to the following
13 * conditions:
14 *
15 * The above copyright notice and this permission notice shall
16 * be included in all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
20 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
22 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
23 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
24 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
25 * OTHER DEALINGS IN THE SOFTWARE.
26 *
27 * ----------------------------------------------------------------------- */
28
29 /*
30 * mem.c
31 *
32 * Obtain a memory map for a Multiboot OS
33 *
34 * This differs from the libcom32 memory map functions in that it doesn't
35 * attempt to filter out memory regions...
36 */
37
38 #include "mboot.h"
39 #include <com32.h>
40
41 struct e820_entry {
42 uint64_t start;
43 uint64_t len;
44 uint32_t type;
45 };
46
47 #define RANGE_ALLOC_BLOCK 128
48
mboot_scan_memory(struct AddrRangeDesc ** ardp,uint32_t * dosmem)49 static int mboot_scan_memory(struct AddrRangeDesc **ardp, uint32_t * dosmem)
50 {
51 com32sys_t ireg, oreg;
52 struct e820_entry *e820buf;
53 struct AddrRangeDesc *ard;
54 size_t ard_count, ard_space;
55 int rv = 0;
56
57 /* Use INT 12h to get DOS memory */
58 __intcall(0x12, &__com32_zero_regs, &oreg);
59 *dosmem = oreg.eax.w[0] << 10;
60 if (*dosmem < 32 * 1024 || *dosmem > 640 * 1024) {
61 /* INT 12h reports nonsense... now what? */
62 uint16_t ebda_seg = *(uint16_t *) 0x40e;
63 if (ebda_seg >= 0x8000 && ebda_seg < 0xa000)
64 *dosmem = ebda_seg << 4;
65 else
66 *dosmem = 640 * 1024; /* Hope for the best... */
67 }
68
69 e820buf = lmalloc(sizeof(*e820buf));
70 if (!e820buf)
71 return 0;
72
73 /* Allocate initial space */
74 *ardp = ard = malloc(RANGE_ALLOC_BLOCK * sizeof *ard);
75 if (!ard)
76 goto out;
77
78 ard_count = 0;
79 ard_space = RANGE_ALLOC_BLOCK;
80
81 /* First try INT 15h AX=E820h */
82 memset(&ireg, 0, sizeof ireg);
83 ireg.eax.l = 0xe820;
84 ireg.edx.l = 0x534d4150;
85 /* ireg.ebx.l = 0; */
86 ireg.ecx.l = sizeof(*e820buf);
87 ireg.es = SEG(e820buf);
88 ireg.edi.w[0] = OFFS(e820buf);
89 memset(e820buf, 0, sizeof *e820buf);
90
91 do {
92 __intcall(0x15, &ireg, &oreg);
93
94 if ((oreg.eflags.l & EFLAGS_CF) ||
95 (oreg.eax.l != 0x534d4150) || (oreg.ecx.l < 20))
96 break;
97
98 if (ard_count >= ard_space) {
99 ard_space += RANGE_ALLOC_BLOCK;
100 *ardp = ard = realloc(ard, ard_space * sizeof *ard);
101 if (!ard) {
102 rv = ard_count;
103 goto out;
104 }
105 }
106
107 ard[ard_count].size = 20;
108 ard[ard_count].BaseAddr = e820buf->start;
109 ard[ard_count].Length = e820buf->len;
110 ard[ard_count].Type = e820buf->type;
111 ard_count++;
112
113 ireg.ebx.l = oreg.ebx.l;
114 } while (oreg.ebx.l);
115
116 if (ard_count) {
117 rv = ard_count;
118 goto out;
119 };
120
121 ard[0].size = 20;
122 ard[0].BaseAddr = 0;
123 ard[0].Length = *dosmem << 10;
124 ard[0].Type = 1;
125
126 /* Next try INT 15h AX=E801h */
127 memset(&ireg, 0, sizeof ireg);
128 ireg.eax.w[0] = 0xe801;
129 __intcall(0x15, &ireg, &oreg);
130
131 if (!(oreg.eflags.l & EFLAGS_CF) && oreg.ecx.w[0]) {
132 ard[1].size = 20;
133 ard[1].BaseAddr = 1 << 20;
134 ard[1].Length = oreg.ecx.w[0] << 10;
135 ard[1].Type = 1;
136
137 if (oreg.edx.w[0]) {
138 ard[2].size = 20;
139 ard[2].BaseAddr = 16 << 20;
140 ard[2].Length = oreg.edx.w[0] << 16;
141 ard[2].Type = 1;
142 rv = 3;
143 } else {
144 rv = 2;
145 }
146
147 goto out;
148 }
149
150 /* Finally try INT 15h AH=88h */
151 memset(&ireg, 0, sizeof ireg);
152 ireg.eax.w[0] = 0x8800;
153 __intcall(0x15, &ireg, &oreg);
154 if (!(oreg.eflags.l & EFLAGS_CF) && oreg.eax.w[0]) {
155 ard[1].size = 20;
156 ard[1].BaseAddr = 1 << 20;
157 ard[1].Length = oreg.ecx.w[0] << 10;
158 ard[1].Type = 1;
159 rv = 2;
160 goto out;
161 }
162
163 rv = 1; /* ... problematic ... */
164 out:
165 lfree(e820buf);
166 return rv;
167 }
168
mboot_make_memmap(void)169 void mboot_make_memmap(void)
170 {
171 int i, nmap;
172 struct AddrRangeDesc *ard;
173 uint32_t lowmem, highmem;
174 uint32_t highrsvd;
175
176 /* Always report DOS memory as "lowmem", this may be overly conservative
177 (e.g. if we're dropping PXE), but it should be *safe*... */
178
179 nmap = mboot_scan_memory(&ard, &lowmem);
180
181 highmem = 0x100000;
182 highrsvd = 0xfff00000;
183
184 again:
185 for (i = 0; i < nmap; i++) {
186 uint64_t start, end;
187
188 start = ard[i].BaseAddr;
189 end = start + ard[i].Length;
190
191 if (end < start)
192 end = ~0ULL;
193
194 if (start & 0xffffffff00000000ULL)
195 continue; /* Not interested in 64-bit memory */
196
197 if (start < highmem)
198 start = highmem;
199
200 if (end <= start)
201 continue;
202
203 if (ard[i].Type == 1 && start == highmem) {
204 highmem = end;
205 goto again;
206 } else if (ard[i].Type != 1 && start < highrsvd)
207 highrsvd = start;
208 }
209
210 if (highmem > highrsvd)
211 highmem = highrsvd;
212
213 mbinfo.mem_lower = lowmem >> 10;
214 mbinfo.mem_upper = (highmem - 0x100000) >> 10;
215 mbinfo.flags |= MB_INFO_MEMORY;
216
217 /* The spec says this address should be +4, but Grub disagrees */
218 mbinfo.mmap_addr = map_data(ard, nmap * sizeof *ard, 4, false);
219 if (mbinfo.mmap_addr) {
220 mbinfo.mmap_length = nmap * sizeof *ard;
221 mbinfo.flags |= MB_INFO_MEM_MAP;
222 }
223 }
224