aboutsummaryrefslogtreecommitdiffstats
path: root/gpxe/src/arch/i386/firmware/pcbios/memmap.c
blob: ff387d93f2b1bdfcf1c6fa1196bd92277d2207f3 (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
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
/*
 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * 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 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, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <stdint.h>
#include <errno.h>
#include <realmode.h>
#include <bios.h>
#include <memsizes.h>
#include <gpxe/memmap.h>

/**
 * @file
 *
 * Memory mapping
 *
 */

/** Magic value for INT 15,e820 calls */
#define SMAP ( 0x534d4150 )

/** An INT 15,e820 memory map entry */
struct e820_entry {
	/** Start of region */
	uint64_t start;
	/** Length of region */
	uint64_t len;
	/** Type of region */
	uint32_t type;
	/** Extended attributes (optional) */
	uint32_t attrs;
} __attribute__ (( packed ));

#define E820_TYPE_RAM		1 /**< Normal memory */
#define E820_TYPE_RESERVED	2 /**< Reserved and unavailable */
#define E820_TYPE_ACPI		3 /**< ACPI reclaim memory */
#define E820_TYPE_NVS		4 /**< ACPI NVS memory */

#define E820_ATTR_ENABLED	0x00000001UL
#define E820_ATTR_NONVOLATILE	0x00000002UL
#define E820_ATTR_UNKNOWN	0xfffffffcUL

#define E820_MIN_SIZE		20

/** Buffer for INT 15,e820 calls */
static struct e820_entry __bss16 ( e820buf );
#define e820buf __use_data16 ( e820buf )

/**
 * Get size of extended memory via INT 15,e801
 *
 * @ret extmem		Extended memory size, in kB, or 0
 */
static unsigned int extmemsize_e801 ( void ) {
	uint16_t extmem_1m_to_16m_k, extmem_16m_plus_64k;
	uint16_t confmem_1m_to_16m_k, confmem_16m_plus_64k;
	unsigned int flags;
	unsigned int extmem;

	__asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
					   "int $0x15\n\t"
					   "pushfw\n\t"
					   "popw %w0\n\t" )
			       : "=r" ( flags ),
				 "=a" ( extmem_1m_to_16m_k ),
				 "=b" ( extmem_16m_plus_64k ),
				 "=c" ( confmem_1m_to_16m_k ),
				 "=d" ( confmem_16m_plus_64k )
			       : "a" ( 0xe801 ) );

	if ( flags & CF ) {
		DBG ( "INT 15,e801 failed with CF set\n" );
		return 0;
	}

	if ( ! ( extmem_1m_to_16m_k | extmem_16m_plus_64k ) ) {
		DBG ( "INT 15,e801 extmem=0, using confmem\n" );
		extmem_1m_to_16m_k = confmem_1m_to_16m_k;
		extmem_16m_plus_64k = confmem_16m_plus_64k;
	}

	extmem = ( extmem_1m_to_16m_k + ( extmem_16m_plus_64k * 64 ) );
	DBG ( "INT 15,e801 extended memory size %d+64*%d=%d kB "
	      "[100000,%llx)\n", extmem_1m_to_16m_k, extmem_16m_plus_64k,
	      extmem, ( 0x100000 + ( ( ( uint64_t ) extmem ) * 1024 ) ) );

	/* Sanity check.  Some BIOSes report the entire 4GB address
	 * space as available, which cannot be correct (since that
	 * would leave no address space available for 32-bit PCI
	 * BARs).
	 */
	if ( extmem == ( 0x400000 - 0x400 ) ) {
		DBG ( "INT 15,e801 reported whole 4GB; assuming insane\n" );
		return 0;
	}

	return extmem;
}

/**
 * Get size of extended memory via INT 15,88
 *
 * @ret extmem		Extended memory size, in kB
 */
static unsigned int extmemsize_88 ( void ) {
	uint16_t extmem;

	/* Ignore CF; it is not reliable for this call */
	__asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
			       : "=a" ( extmem ) : "a" ( 0x8800 ) );

	DBG ( "INT 15,88 extended memory size %d kB [100000, %x)\n",
	      extmem, ( 0x100000 + ( extmem * 1024 ) ) );
	return extmem;
}

/**
 * Get size of extended memory
 *
 * @ret extmem		Extended memory size, in kB
 *
 * Note that this is only an approximation; for an accurate picture,
 * use the E820 memory map obtained via get_memmap();
 */
unsigned int extmemsize ( void ) {
	unsigned int extmem;

	/* Try INT 15,e801 first, then fall back to INT 15,88 */
	extmem = extmemsize_e801();
	if ( ! extmem )
		extmem = extmemsize_88();
	return extmem;
}

/**
 * Get e820 memory map
 *
 * @v memmap		Memory map to fill in
 * @ret rc		Return status code
 */
static int meme820 ( struct memory_map *memmap ) {
	struct memory_region *region = memmap->regions;
	uint32_t next = 0;
	uint32_t smap;
	size_t size;
	unsigned int flags;
	unsigned int discard_D;

	/* Clear the E820 buffer.  Do this once before starting,
	 * rather than on each call; some BIOSes rely on the contents
	 * being preserved between calls.
	 */
	memset ( &e820buf, 0, sizeof ( e820buf ) );

	do {
		/* Some BIOSes corrupt %esi for fun. Guard against
		 * this by telling gcc that all non-output registers
		 * may be corrupted.
		 */
		__asm__ __volatile__ ( REAL_CODE ( "pushl %%ebp\n\t"
						   "stc\n\t"
						   "int $0x15\n\t"
						   "pushfw\n\t"
						   "popw %%dx\n\t"
						   "popl %%ebp\n\t" )
				       : "=a" ( smap ), "=b" ( next ),
					 "=c" ( size ), "=d" ( flags ),
					 "=D" ( discard_D )
				       : "a" ( 0xe820 ), "b" ( next ),
					 "D" ( __from_data16 ( &e820buf ) ),
					 "c" ( sizeof ( e820buf ) ),
					 "d" ( SMAP )
				       : "esi", "memory" );

		if ( smap != SMAP ) {
			DBG ( "INT 15,e820 failed SMAP signature check\n" );
			return -ENOTSUP;
		}

		if ( size < E820_MIN_SIZE ) {
			DBG ( "INT 15,e820 returned only %zd bytes\n", size );
			return -EINVAL;
		}

		if ( flags & CF ) {
			DBG ( "INT 15,e820 terminated on CF set\n" );
			break;
		}

		/* If first region is not RAM, assume map is invalid */
		if ( ( memmap->count == 0 ) &&
		     ( e820buf.type != E820_TYPE_RAM ) ) {
		       DBG ( "INT 15,e820 failed, first entry not RAM\n" );
		       return -EINVAL;
		}

		DBG ( "INT 15,e820 region [%llx,%llx) type %d",
		      e820buf.start, ( e820buf.start + e820buf.len ),
		      ( int ) e820buf.type );
		if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
			DBG ( " (%s", ( ( e820buf.attrs & E820_ATTR_ENABLED )
					? "enabled" : "disabled" ) );
			if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
				DBG ( ", non-volatile" );
			if ( e820buf.attrs & E820_ATTR_UNKNOWN )
				DBG ( ", other [%08x]", e820buf.attrs );
			DBG ( ")" );
		}
		DBG ( "\n" );

		/* Discard non-RAM regions */
		if ( e820buf.type != E820_TYPE_RAM )
			continue;

		/* Check extended attributes, if present */
		if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
			if ( ! ( e820buf.attrs & E820_ATTR_ENABLED ) )
				continue;
			if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
				continue;
		}

		region->start = e820buf.start;
		region->end = e820buf.start + e820buf.len;
		region++;
		memmap->count++;

		if ( memmap->count >= ( sizeof ( memmap->regions ) /
					sizeof ( memmap->regions[0] ) ) ) {
			DBG ( "INT 15,e820 too many regions returned\n" );
			/* Not a fatal error; what we've got so far at
			 * least represents valid regions of memory,
			 * even if we couldn't get them all.
			 */
			break;
		}
	} while ( next != 0 );

	/* Sanity checks.  Some BIOSes report complete garbage via INT
	 * 15,e820 (especially at POST time), despite passing the
	 * signature checks.  We currently check for a base memory
	 * region (starting at 0) and at least one high memory region
	 * (starting at 0x100000).
	 */
	if ( memmap->count < 2 ) {
		DBG ( "INT 15,e820 returned only %d regions; assuming "
		      "insane\n", memmap->count );
		return -EINVAL;
	}
	if ( memmap->regions[0].start != 0 ) {
		DBG ( "INT 15,e820 region 0 starts at %llx (expected 0); "
		      "assuming insane\n", memmap->regions[0].start );
		return -EINVAL;
	}
	if ( memmap->regions[1].start != 0x100000 ) {
		DBG ( "INT 15,e820 region 1 starts at %llx (expected 100000); "
		      "assuming insane\n", memmap->regions[0].start );
		return -EINVAL;
	}

	return 0;
}

/**
 * Get memory map
 *
 * @v memmap		Memory map to fill in
 */
void get_memmap ( struct memory_map *memmap ) {
	unsigned int basemem, extmem;
	int rc;

	DBG ( "Fetching system memory map\n" );

	/* Clear memory map */
	memset ( memmap, 0, sizeof ( *memmap ) );

	/* Get base and extended memory sizes */
	basemem = basememsize();
	DBG ( "FBMS base memory size %d kB [0,%x)\n",
	      basemem, ( basemem * 1024 ) );
	extmem = extmemsize();
	
	/* Try INT 15,e820 first */
	if ( ( rc = meme820 ( memmap ) ) == 0 ) {
		DBG ( "Obtained system memory map via INT 15,e820\n" );
		return;
	}

	/* Fall back to constructing a map from basemem and extmem sizes */
	DBG ( "INT 15,e820 failed; constructing map\n" );
	memmap->regions[0].end = ( basemem * 1024 );
	memmap->regions[1].start = 0x100000;
	memmap->regions[1].end = 0x100000 + ( extmem * 1024 );
	memmap->count = 2;
}