summaryrefslogtreecommitdiff
path: root/gpxe/src/arch/i386/image/bzimage.c
blob: 194509905a096b1e66f81daaa5e756dc589a0a98 (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
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
/*
 * Copyright (C) 2007 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.
 */

FILE_LICENCE ( GPL2_OR_LATER );

/**
 * @file
 *
 * Linux bzImage image format
 *
 */

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <realmode.h>
#include <bzimage.h>
#include <gpxe/uaccess.h>
#include <gpxe/image.h>
#include <gpxe/segment.h>
#include <gpxe/init.h>
#include <gpxe/cpio.h>
#include <gpxe/features.h>

FEATURE ( FEATURE_IMAGE, "bzImage", DHCP_EB_FEATURE_BZIMAGE, 1 );

struct image_type bzimage_image_type __image_type ( PROBE_NORMAL );

/**
 * bzImage context
 */
struct bzimage_context {
	/** Boot protocol version */
	unsigned int version;
	/** Real-mode kernel portion load segment address */
	unsigned int rm_kernel_seg;
	/** Real-mode kernel portion load address */
	userptr_t rm_kernel;
	/** Real-mode kernel portion file size */
	size_t rm_filesz;
	/** Real-mode heap top (offset from rm_kernel) */
	size_t rm_heap;
	/** Command line (offset from rm_kernel) */
	size_t rm_cmdline;
	/** Command line maximum length */
	size_t cmdline_size;
	/** Real-mode kernel portion total memory size */
	size_t rm_memsz;
	/** Non-real-mode kernel portion load address */
	userptr_t pm_kernel;
	/** Non-real-mode kernel portion file and memory size */
	size_t pm_sz;
	/** Video mode */
	unsigned int vid_mode;
	/** Memory limit */
	uint64_t mem_limit;
	/** Initrd address */
	physaddr_t ramdisk_image;
	/** Initrd size */
	physaddr_t ramdisk_size;

	/** Command line magic block */
	struct bzimage_cmdline cmdline_magic;
	/** bzImage header */
	struct bzimage_header bzhdr;
};

/**
 * Parse bzImage header
 *
 * @v image		bzImage file
 * @v bzimg		bzImage context
 * @v src		bzImage to parse
 * @ret rc		Return status code
 */
static int bzimage_parse_header ( struct image *image,
				  struct bzimage_context *bzimg,
				  userptr_t src ) {
	unsigned int syssize;
	int is_bzimage;

	/* Sanity check */
	if ( image->len < ( BZI_HDR_OFFSET + sizeof ( bzimg->bzhdr ) ) ) {
		DBGC ( image, "bzImage %p too short for kernel header\n",
		       image );
		return -ENOEXEC;
	}

	/* Read in header structures */
	memset ( bzimg, 0, sizeof ( *bzimg ) );
	copy_from_user ( &bzimg->cmdline_magic, src, BZI_CMDLINE_OFFSET,
			 sizeof ( bzimg->cmdline_magic ) );
	copy_from_user ( &bzimg->bzhdr, src, BZI_HDR_OFFSET,
			 sizeof ( bzimg->bzhdr ) );

	/* Calculate size of real-mode portion */
	bzimg->rm_filesz =
		( ( bzimg->bzhdr.setup_sects ? bzimg->bzhdr.setup_sects : 4 ) + 1 ) << 9;
	if ( bzimg->rm_filesz > image->len ) {
		DBGC ( image, "bzImage %p too short for %zd byte of setup\n",
		       image, bzimg->rm_filesz );
		return -ENOEXEC;
	}
	bzimg->rm_memsz = BZI_ASSUMED_RM_SIZE;

	/* Calculate size of protected-mode portion */
	bzimg->pm_sz = ( image->len - bzimg->rm_filesz );
	syssize = ( ( bzimg->pm_sz + 15 ) / 16 );

	/* Check for signatures and determine version */
	if ( bzimg->bzhdr.boot_flag != BZI_BOOT_FLAG ) {
		DBGC ( image, "bzImage %p missing 55AA signature\n", image );
		return -ENOEXEC;
	}
	if ( bzimg->bzhdr.header == BZI_SIGNATURE ) {
		/* 2.00+ */
		bzimg->version = bzimg->bzhdr.version;
	} else {
		/* Pre-2.00.  Check that the syssize field is correct,
		 * as a guard against accepting arbitrary binary data,
		 * since the 55AA check is pretty lax.  Note that the
		 * syssize field is unreliable for protocols between
		 * 2.00 and 2.03 inclusive, so we should not always
		 * check this field.
		 */
		bzimg->version = 0x0100;
		if ( bzimg->bzhdr.syssize != syssize ) {
			DBGC ( image, "bzImage %p bad syssize %x (expected "
			       "%x)\n", image, bzimg->bzhdr.syssize, syssize );
			return -ENOEXEC;
		}
	}

	/* Determine image type */
	is_bzimage = ( ( bzimg->version >= 0x0200 ) ?
		       ( bzimg->bzhdr.loadflags & BZI_LOAD_HIGH ) : 0 );

	/* Calculate load address of real-mode portion */
	bzimg->rm_kernel_seg = ( is_bzimage ? 0x1000 : 0x9000 );
	bzimg->rm_kernel = real_to_user ( bzimg->rm_kernel_seg, 0 );

	/* Allow space for the stack and heap */
	bzimg->rm_memsz += BZI_STACK_SIZE;
	bzimg->rm_heap = bzimg->rm_memsz;

	/* Allow space for the command line */
	bzimg->rm_cmdline = bzimg->rm_memsz;
	bzimg->rm_memsz += BZI_CMDLINE_SIZE;

	/* Calculate load address of protected-mode portion */
	bzimg->pm_kernel = phys_to_user ( is_bzimage ? BZI_LOAD_HIGH_ADDR
					: BZI_LOAD_LOW_ADDR );

	/* Extract video mode */
	bzimg->vid_mode = bzimg->bzhdr.vid_mode;

	/* Extract memory limit */
	bzimg->mem_limit = ( ( bzimg->version >= 0x0203 ) ?
			     bzimg->bzhdr.initrd_addr_max : BZI_INITRD_MAX );

	/* Extract command line size */
	bzimg->cmdline_size = ( ( bzimg->version >= 0x0206 ) ?
				bzimg->bzhdr.cmdline_size : BZI_CMDLINE_SIZE );

	DBGC ( image, "bzImage %p version %04x RM %#lx+%#zx PM %#lx+%#zx "
	       "cmdlen %zd\n", image, bzimg->version,
	       user_to_phys ( bzimg->rm_kernel, 0 ), bzimg->rm_filesz,
	       user_to_phys ( bzimg->pm_kernel, 0 ), bzimg->pm_sz,
	       bzimg->cmdline_size );

	return 0;
}

/**
 * Update bzImage header in loaded kernel
 *
 * @v image		bzImage file
 * @v bzimg		bzImage context
 * @v dst		bzImage to update
 */
static void bzimage_update_header ( struct image *image,
				    struct bzimage_context *bzimg,
				    userptr_t dst ) {

	/* Set loader type */
	if ( bzimg->version >= 0x0200 )
		bzimg->bzhdr.type_of_loader = BZI_LOADER_TYPE_GPXE;

	/* Set heap end pointer */
	if ( bzimg->version >= 0x0201 ) {
		bzimg->bzhdr.heap_end_ptr = ( bzimg->rm_heap - 0x200 );
		bzimg->bzhdr.loadflags |= BZI_CAN_USE_HEAP;
	}

	/* Set command line */
	if ( bzimg->version >= 0x0202 ) {
		bzimg->bzhdr.cmd_line_ptr = user_to_phys ( bzimg->rm_kernel,
							   bzimg->rm_cmdline );
	} else {
		bzimg->cmdline_magic.magic = BZI_CMDLINE_MAGIC;
		bzimg->cmdline_magic.offset = bzimg->rm_cmdline;
		bzimg->bzhdr.setup_move_size = bzimg->rm_memsz;
	}

	/* Set video mode */
	bzimg->bzhdr.vid_mode = bzimg->vid_mode;

	/* Set initrd address */
	if ( bzimg->version >= 0x0200 ) {
		bzimg->bzhdr.ramdisk_image = bzimg->ramdisk_image;
		bzimg->bzhdr.ramdisk_size = bzimg->ramdisk_size;
	}

	/* Write out header structures */
	copy_to_user ( dst, BZI_CMDLINE_OFFSET, &bzimg->cmdline_magic,
		       sizeof ( bzimg->cmdline_magic ) );
	copy_to_user ( dst, BZI_HDR_OFFSET, &bzimg->bzhdr,
		       sizeof ( bzimg->bzhdr ) );

	DBGC ( image, "bzImage %p vidmode %d\n", image, bzimg->vid_mode );
}

/**
 * Parse kernel command line for bootloader parameters
 *
 * @v image		bzImage file
 * @v bzimg		bzImage context
 * @v cmdline		Kernel command line
 * @ret rc		Return status code
 */
static int bzimage_parse_cmdline ( struct image *image,
				   struct bzimage_context *bzimg,
				   const char *cmdline ) {
	char *vga;
	char *mem;

	/* Look for "vga=" */
	if ( ( vga = strstr ( cmdline, "vga=" ) ) ) {
		vga += 4;
		if ( strcmp ( vga, "normal" ) == 0 ) {
			bzimg->vid_mode = BZI_VID_MODE_NORMAL;
		} else if ( strcmp ( vga, "ext" ) == 0 ) {
			bzimg->vid_mode = BZI_VID_MODE_EXT;
		} else if ( strcmp ( vga, "ask" ) == 0 ) {
			bzimg->vid_mode = BZI_VID_MODE_ASK;
		} else {
			bzimg->vid_mode = strtoul ( vga, &vga, 0 );
			if ( *vga && ( *vga != ' ' ) ) {
				DBGC ( image, "bzImage %p strange \"vga=\""
				       "terminator '%c'\n", image, *vga );
			}
		}
	}

	/* Look for "mem=" */
	if ( ( mem = strstr ( cmdline, "mem=" ) ) ) {
		mem += 4;
		bzimg->mem_limit = strtoul ( mem, &mem, 0 );
		switch ( *mem ) {
		case 'G':
		case 'g':
			bzimg->mem_limit <<= 10;
		case 'M':
		case 'm':
			bzimg->mem_limit <<= 10;
		case 'K':
		case 'k':
			bzimg->mem_limit <<= 10;
			break;
		case '\0':
		case ' ':
			break;
		default:
			DBGC ( image, "bzImage %p strange \"mem=\" "
			       "terminator '%c'\n", image, *mem );
			break;
		}
		bzimg->mem_limit -= 1;
	}

	return 0;
}

/**
 * Set command line
 *
 * @v image		bzImage image
 * @v bzimg		bzImage context
 * @v cmdline		Kernel command line
 * @ret rc		Return status code
 */
static int bzimage_set_cmdline ( struct image *image,
				 struct bzimage_context *bzimg,
				 const char *cmdline ) {
	size_t cmdline_len;

	/* Copy command line down to real-mode portion */
	cmdline_len = ( strlen ( cmdline ) + 1 );
	if ( cmdline_len > bzimg->cmdline_size )
		cmdline_len = bzimg->cmdline_size;
	copy_to_user ( bzimg->rm_kernel, bzimg->rm_cmdline,
		       cmdline, cmdline_len );
	DBGC ( image, "bzImage %p command line \"%s\"\n", image, cmdline );

	return 0;
}

/**
 * Load initrd
 *
 * @v image		bzImage image
 * @v initrd		initrd image
 * @v address		Address at which to load, or UNULL
 * @ret len		Length of loaded image, rounded up to 4 bytes
 */
static size_t bzimage_load_initrd ( struct image *image,
				    struct image *initrd,
				    userptr_t address ) {
	char *filename = initrd->cmdline;
	struct cpio_header cpio;
        size_t offset = 0;

	/* Do not include kernel image itself as an initrd */
	if ( initrd == image )
		return 0;

	/* Create cpio header before non-prebuilt images */
	if ( filename && filename[0] ) {
		size_t name_len = ( strlen ( filename ) + 1 );

		DBGC ( image, "bzImage %p inserting initrd %p as %s\n",
		       image, initrd, filename );
		memset ( &cpio, '0', sizeof ( cpio ) );
		memcpy ( cpio.c_magic, CPIO_MAGIC, sizeof ( cpio.c_magic ) );
		cpio_set_field ( cpio.c_mode, 0100644 );
		cpio_set_field ( cpio.c_nlink, 1 );
		cpio_set_field ( cpio.c_filesize, initrd->len );
		cpio_set_field ( cpio.c_namesize, name_len );
		if ( address ) {
			copy_to_user ( address, offset, &cpio,
				       sizeof ( cpio ) );
		}
		offset += sizeof ( cpio );
		if ( address ) {
			copy_to_user ( address, offset, filename,
				       name_len );
		}
		offset += name_len;
		offset = ( ( offset + 0x03 ) & ~0x03 );
	}

	/* Copy in initrd image body */
	if ( address )
		memcpy_user ( address, offset, initrd->data, 0, initrd->len );
	offset += initrd->len;
	if ( address ) {
		DBGC ( image, "bzImage %p has initrd %p at [%lx,%lx)\n",
		       image, initrd, user_to_phys ( address, 0 ),
		       user_to_phys ( address, offset ) );
	}

	/* Round up to 4-byte boundary */
	offset = ( ( offset + 0x03 ) & ~0x03 );
	return offset;
}

/**
 * Load initrds, if any
 *
 * @v image		bzImage image
 * @v bzimg		bzImage context
 * @ret rc		Return status code
 */
static int bzimage_load_initrds ( struct image *image,
				  struct bzimage_context *bzimg ) {
	struct image *initrd;
	size_t total_len = 0;
	physaddr_t address;
	int rc;

	/* Add up length of all initrd images */
	for_each_image ( initrd )
		total_len += bzimage_load_initrd ( image, initrd, UNULL );

	/* Give up if no initrd images found */
	if ( ! total_len )
		return 0;

	/* Find a suitable start address.  Try 1MB boundaries,
	 * starting from the downloaded kernel image itself and
	 * working downwards until we hit an available region.
	 */
	for ( address = ( user_to_phys ( image->data, 0 ) & ~0xfffff ) ; ;
	      address -= 0x100000 ) {
		/* Check that we're not going to overwrite the
		 * kernel itself.  This check isn't totally
		 * accurate, but errs on the side of caution.
		 */
		if ( address <= ( BZI_LOAD_HIGH_ADDR + image->len ) ) {
			DBGC ( image, "bzImage %p could not find a location "
			       "for initrd\n", image );
			return -ENOBUFS;
		}
		/* Check that we are within the kernel's range */
		if ( ( address + total_len - 1 ) > bzimg->mem_limit )
			continue;
		/* Prepare and verify segment */
		if ( ( rc = prep_segment ( phys_to_user ( address ), 0,
					   total_len ) ) != 0 )
			continue;
		/* Use this address */
		break;
	}

	/* Record initrd location */
	bzimg->ramdisk_image = address;
	bzimg->ramdisk_size = total_len;

	/* Construct initrd */
	DBGC ( image, "bzImage %p constructing initrd at [%lx,%lx)\n",
	       image, address, ( address + total_len ) );
	for_each_image ( initrd ) {
		address += bzimage_load_initrd ( image, initrd,
						 phys_to_user ( address ) );
	}

	return 0;
}

/**
 * Execute bzImage image
 *
 * @v image		bzImage image
 * @ret rc		Return status code
 */
static int bzimage_exec ( struct image *image ) {
	struct bzimage_context bzimg;
	const char *cmdline = ( image->cmdline ? image->cmdline : "" );
	int rc;

	/* Read and parse header from loaded kernel */
	if ( ( rc = bzimage_parse_header ( image, &bzimg,
					   image->priv.user ) ) != 0 )
		return rc;
	assert ( bzimg.rm_kernel == image->priv.user );

	/* Parse command line for bootloader parameters */
	if ( ( rc = bzimage_parse_cmdline ( image, &bzimg, cmdline ) ) != 0)
		return rc;

	/* Store command line */
	if ( ( rc = bzimage_set_cmdline ( image, &bzimg, cmdline ) ) != 0 )
		return rc;

	/* Load any initrds */
	if ( ( rc = bzimage_load_initrds ( image, &bzimg ) ) != 0 )
		return rc;

	/* Update kernel header */
	bzimage_update_header ( image, &bzimg, bzimg.rm_kernel );

	/* Prepare for exiting */
	shutdown ( SHUTDOWN_BOOT );

	DBGC ( image, "bzImage %p jumping to RM kernel at %04x:0000 "
	       "(stack %04x:%04zx)\n", image, ( bzimg.rm_kernel_seg + 0x20 ),
	       bzimg.rm_kernel_seg, bzimg.rm_heap );

	/* Jump to the kernel */
	__asm__ __volatile__ ( REAL_CODE ( "movw %w0, %%ds\n\t"
					   "movw %w0, %%es\n\t"
					   "movw %w0, %%fs\n\t"
					   "movw %w0, %%gs\n\t"
					   "movw %w0, %%ss\n\t"
					   "movw %w1, %%sp\n\t"
					   "pushw %w2\n\t"
					   "pushw $0\n\t"
					   "lret\n\t" )
			       : : "r" ( bzimg.rm_kernel_seg ),
			           "r" ( bzimg.rm_heap ),
			           "r" ( bzimg.rm_kernel_seg + 0x20 ) );

	/* There is no way for the image to return, since we provide
	 * no return address.
	 */
	assert ( 0 );

	return -ECANCELED; /* -EIMPOSSIBLE */
}

/**
 * Load bzImage image into memory
 *
 * @v image		bzImage file
 * @ret rc		Return status code
 */
int bzimage_load ( struct image *image ) {
	struct bzimage_context bzimg;
	int rc;

	/* Read and parse header from image */
	if ( ( rc = bzimage_parse_header ( image, &bzimg,
					   image->data ) ) != 0 )
		return rc;

	/* This is a bzImage image, valid or otherwise */
	if ( ! image->type )
		image->type = &bzimage_image_type;

	/* Prepare segments */
	if ( ( rc = prep_segment ( bzimg.rm_kernel, bzimg.rm_filesz,
				   bzimg.rm_memsz ) ) != 0 ) {
		DBGC ( image, "bzImage %p could not prepare RM segment: %s\n",
		       image, strerror ( rc ) );
		return rc;
	}
	if ( ( rc = prep_segment ( bzimg.pm_kernel, bzimg.pm_sz,
				   bzimg.pm_sz ) ) != 0 ) {
		DBGC ( image, "bzImage %p could not prepare PM segment: %s\n",
		       image, strerror ( rc ) );
		return rc;
	}

	/* Load segments */
	memcpy_user ( bzimg.rm_kernel, 0, image->data,
		      0, bzimg.rm_filesz );
	memcpy_user ( bzimg.pm_kernel, 0, image->data,
		      bzimg.rm_filesz, bzimg.pm_sz );

	/* Update and write out header */
	bzimage_update_header ( image, &bzimg, bzimg.rm_kernel );

	/* Record real-mode segment in image private data field */
	image->priv.user = bzimg.rm_kernel;

	return 0;
}

/** Linux bzImage image type */
struct image_type bzimage_image_type __image_type ( PROBE_NORMAL ) = {
	.name = "bzImage",
	.load = bzimage_load,
	.exec = bzimage_exec,
};