1 /*
2 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * 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, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19 FILE_LICENCE ( GPL2_OR_LATER );
20
21 #include <stdint.h>
22 #include <errno.h>
23 #include <realmode.h>
24 #include <bios.h>
25 #include <memsizes.h>
26 #include <gpxe/memmap.h>
27
28 /**
29 * @file
30 *
31 * Memory mapping
32 *
33 */
34
35 /** Magic value for INT 15,e820 calls */
36 #define SMAP ( 0x534d4150 )
37
38 /** An INT 15,e820 memory map entry */
39 struct e820_entry {
40 /** Start of region */
41 uint64_t start;
42 /** Length of region */
43 uint64_t len;
44 /** Type of region */
45 uint32_t type;
46 /** Extended attributes (optional) */
47 uint32_t attrs;
48 } __attribute__ (( packed ));
49
50 #define E820_TYPE_RAM 1 /**< Normal memory */
51 #define E820_TYPE_RESERVED 2 /**< Reserved and unavailable */
52 #define E820_TYPE_ACPI 3 /**< ACPI reclaim memory */
53 #define E820_TYPE_NVS 4 /**< ACPI NVS memory */
54
55 #define E820_ATTR_ENABLED 0x00000001UL
56 #define E820_ATTR_NONVOLATILE 0x00000002UL
57 #define E820_ATTR_UNKNOWN 0xfffffffcUL
58
59 #define E820_MIN_SIZE 20
60
61 /** Buffer for INT 15,e820 calls */
62 static struct e820_entry __bss16 ( e820buf );
63 #define e820buf __use_data16 ( e820buf )
64
65 /**
66 * Get size of extended memory via INT 15,e801
67 *
68 * @ret extmem Extended memory size, in kB, or 0
69 */
extmemsize_e801(void)70 static unsigned int extmemsize_e801 ( void ) {
71 uint16_t extmem_1m_to_16m_k, extmem_16m_plus_64k;
72 uint16_t confmem_1m_to_16m_k, confmem_16m_plus_64k;
73 unsigned int flags;
74 unsigned int extmem;
75
76 __asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
77 "int $0x15\n\t"
78 "pushfw\n\t"
79 "popw %w0\n\t" )
80 : "=r" ( flags ),
81 "=a" ( extmem_1m_to_16m_k ),
82 "=b" ( extmem_16m_plus_64k ),
83 "=c" ( confmem_1m_to_16m_k ),
84 "=d" ( confmem_16m_plus_64k )
85 : "a" ( 0xe801 ) );
86
87 if ( flags & CF ) {
88 DBG ( "INT 15,e801 failed with CF set\n" );
89 return 0;
90 }
91
92 if ( ! ( extmem_1m_to_16m_k | extmem_16m_plus_64k ) ) {
93 DBG ( "INT 15,e801 extmem=0, using confmem\n" );
94 extmem_1m_to_16m_k = confmem_1m_to_16m_k;
95 extmem_16m_plus_64k = confmem_16m_plus_64k;
96 }
97
98 extmem = ( extmem_1m_to_16m_k + ( extmem_16m_plus_64k * 64 ) );
99 DBG ( "INT 15,e801 extended memory size %d+64*%d=%d kB "
100 "[100000,%llx)\n", extmem_1m_to_16m_k, extmem_16m_plus_64k,
101 extmem, ( 0x100000 + ( ( ( uint64_t ) extmem ) * 1024 ) ) );
102
103 /* Sanity check. Some BIOSes report the entire 4GB address
104 * space as available, which cannot be correct (since that
105 * would leave no address space available for 32-bit PCI
106 * BARs).
107 */
108 if ( extmem == ( 0x400000 - 0x400 ) ) {
109 DBG ( "INT 15,e801 reported whole 4GB; assuming insane\n" );
110 return 0;
111 }
112
113 return extmem;
114 }
115
116 /**
117 * Get size of extended memory via INT 15,88
118 *
119 * @ret extmem Extended memory size, in kB
120 */
extmemsize_88(void)121 static unsigned int extmemsize_88 ( void ) {
122 uint16_t extmem;
123
124 /* Ignore CF; it is not reliable for this call */
125 __asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
126 : "=a" ( extmem ) : "a" ( 0x8800 ) );
127
128 DBG ( "INT 15,88 extended memory size %d kB [100000, %x)\n",
129 extmem, ( 0x100000 + ( extmem * 1024 ) ) );
130 return extmem;
131 }
132
133 /**
134 * Get size of extended memory
135 *
136 * @ret extmem Extended memory size, in kB
137 *
138 * Note that this is only an approximation; for an accurate picture,
139 * use the E820 memory map obtained via get_memmap();
140 */
extmemsize(void)141 unsigned int extmemsize ( void ) {
142 unsigned int extmem;
143
144 /* Try INT 15,e801 first, then fall back to INT 15,88 */
145 extmem = extmemsize_e801();
146 if ( ! extmem )
147 extmem = extmemsize_88();
148 return extmem;
149 }
150
151 /**
152 * Get e820 memory map
153 *
154 * @v memmap Memory map to fill in
155 * @ret rc Return status code
156 */
meme820(struct memory_map * memmap)157 static int meme820 ( struct memory_map *memmap ) {
158 struct memory_region *region = memmap->regions;
159 uint32_t next = 0;
160 uint32_t smap;
161 size_t size;
162 unsigned int flags;
163 unsigned int discard_D;
164
165 /* Clear the E820 buffer. Do this once before starting,
166 * rather than on each call; some BIOSes rely on the contents
167 * being preserved between calls.
168 */
169 memset ( &e820buf, 0, sizeof ( e820buf ) );
170
171 do {
172 /* Some BIOSes corrupt %esi for fun. Guard against
173 * this by telling gcc that all non-output registers
174 * may be corrupted.
175 */
176 __asm__ __volatile__ ( REAL_CODE ( "pushl %%ebp\n\t"
177 "stc\n\t"
178 "int $0x15\n\t"
179 "pushfw\n\t"
180 "popw %%dx\n\t"
181 "popl %%ebp\n\t" )
182 : "=a" ( smap ), "=b" ( next ),
183 "=c" ( size ), "=d" ( flags ),
184 "=D" ( discard_D )
185 : "a" ( 0xe820 ), "b" ( next ),
186 "D" ( __from_data16 ( &e820buf ) ),
187 "c" ( sizeof ( e820buf ) ),
188 "d" ( SMAP )
189 : "esi", "memory" );
190
191 if ( smap != SMAP ) {
192 DBG ( "INT 15,e820 failed SMAP signature check\n" );
193 return -ENOTSUP;
194 }
195
196 if ( size < E820_MIN_SIZE ) {
197 DBG ( "INT 15,e820 returned only %zd bytes\n", size );
198 return -EINVAL;
199 }
200
201 if ( flags & CF ) {
202 DBG ( "INT 15,e820 terminated on CF set\n" );
203 break;
204 }
205
206 /* If first region is not RAM, assume map is invalid */
207 if ( ( memmap->count == 0 ) &&
208 ( e820buf.type != E820_TYPE_RAM ) ) {
209 DBG ( "INT 15,e820 failed, first entry not RAM\n" );
210 return -EINVAL;
211 }
212
213 DBG ( "INT 15,e820 region [%llx,%llx) type %d",
214 e820buf.start, ( e820buf.start + e820buf.len ),
215 ( int ) e820buf.type );
216 if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
217 DBG ( " (%s", ( ( e820buf.attrs & E820_ATTR_ENABLED )
218 ? "enabled" : "disabled" ) );
219 if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
220 DBG ( ", non-volatile" );
221 if ( e820buf.attrs & E820_ATTR_UNKNOWN )
222 DBG ( ", other [%08x]", e820buf.attrs );
223 DBG ( ")" );
224 }
225 DBG ( "\n" );
226
227 /* Discard non-RAM regions */
228 if ( e820buf.type != E820_TYPE_RAM )
229 continue;
230
231 /* Check extended attributes, if present */
232 if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
233 if ( ! ( e820buf.attrs & E820_ATTR_ENABLED ) )
234 continue;
235 if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
236 continue;
237 }
238
239 region->start = e820buf.start;
240 region->end = e820buf.start + e820buf.len;
241 region++;
242 memmap->count++;
243
244 if ( memmap->count >= ( sizeof ( memmap->regions ) /
245 sizeof ( memmap->regions[0] ) ) ) {
246 DBG ( "INT 15,e820 too many regions returned\n" );
247 /* Not a fatal error; what we've got so far at
248 * least represents valid regions of memory,
249 * even if we couldn't get them all.
250 */
251 break;
252 }
253 } while ( next != 0 );
254
255 /* Sanity checks. Some BIOSes report complete garbage via INT
256 * 15,e820 (especially at POST time), despite passing the
257 * signature checks. We currently check for a base memory
258 * region (starting at 0) and at least one high memory region
259 * (starting at 0x100000).
260 */
261 if ( memmap->count < 2 ) {
262 DBG ( "INT 15,e820 returned only %d regions; assuming "
263 "insane\n", memmap->count );
264 return -EINVAL;
265 }
266 if ( memmap->regions[0].start != 0 ) {
267 DBG ( "INT 15,e820 region 0 starts at %llx (expected 0); "
268 "assuming insane\n", memmap->regions[0].start );
269 return -EINVAL;
270 }
271 if ( memmap->regions[1].start != 0x100000 ) {
272 DBG ( "INT 15,e820 region 1 starts at %llx (expected 100000); "
273 "assuming insane\n", memmap->regions[0].start );
274 return -EINVAL;
275 }
276
277 return 0;
278 }
279
280 /**
281 * Get memory map
282 *
283 * @v memmap Memory map to fill in
284 */
get_memmap(struct memory_map * memmap)285 void get_memmap ( struct memory_map *memmap ) {
286 unsigned int basemem, extmem;
287 int rc;
288
289 DBG ( "Fetching system memory map\n" );
290
291 /* Clear memory map */
292 memset ( memmap, 0, sizeof ( *memmap ) );
293
294 /* Get base and extended memory sizes */
295 basemem = basememsize();
296 DBG ( "FBMS base memory size %d kB [0,%x)\n",
297 basemem, ( basemem * 1024 ) );
298 extmem = extmemsize();
299
300 /* Try INT 15,e820 first */
301 if ( ( rc = meme820 ( memmap ) ) == 0 ) {
302 DBG ( "Obtained system memory map via INT 15,e820\n" );
303 return;
304 }
305
306 /* Fall back to constructing a map from basemem and extmem sizes */
307 DBG ( "INT 15,e820 failed; constructing map\n" );
308 memmap->regions[0].end = ( basemem * 1024 );
309 memmap->regions[1].start = 0x100000;
310 memmap->regions[1].end = 0x100000 + ( extmem * 1024 );
311 memmap->count = 2;
312 }
313