summaryrefslogtreecommitdiff
path: root/src/boot/elfboot.c
blob: f2c5975b11f79b03f5605b999a5cef79bc5e8f32 (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
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
#include <console/console.h>
#include <part/fallback_boot.h>
#include <boot/elf.h>
#include <boot/elf_boot.h>
#include <boot/coreboot_tables.h>
#include <ip_checksum.h>
#include <stream/read_bytes.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

/* Maximum physical address we can use for the coreboot bounce buffer.
 */
#ifndef MAX_ADDR
#define MAX_ADDR -1UL
#endif

extern unsigned char _ram_seg;
extern unsigned char _eram_seg;

struct segment {
	struct segment *next;
	struct segment *prev;
	struct segment *phdr_next;
	struct segment *phdr_prev;
	unsigned long s_addr;
	unsigned long s_memsz;
	unsigned long s_offset;
	unsigned long s_filesz;
};

struct verify_callback {
	struct verify_callback *next;
	int (*callback)(struct verify_callback *vcb, 
		Elf_ehdr *ehdr, Elf_phdr *phdr, struct segment *head);
	unsigned long desc_offset;
	unsigned long desc_addr;
};

struct ip_checksum_vcb {
	struct verify_callback data;
	unsigned short ip_checksum;
};

int verify_ip_checksum(
	struct verify_callback *vcb, 
	Elf_ehdr *ehdr, Elf_phdr *phdr, struct segment *head)
{
	struct ip_checksum_vcb *cb;
	struct segment *ptr;
	unsigned long bytes;
	unsigned long checksum;
	unsigned char buff[2], *n_desc;
	cb = (struct ip_checksum_vcb *)vcb;
	/* zero the checksum so it's value won't
	 * get in the way of verifying the checksum.
	 */
	n_desc = 0;
	if (vcb->desc_addr) {
		n_desc = (unsigned char *)(vcb->desc_addr);
		memcpy(buff, n_desc, 2);
		memset(n_desc, 0, 2);
	}
	bytes = 0;
	checksum = compute_ip_checksum(ehdr, sizeof(*ehdr));
	bytes += sizeof(*ehdr);
	checksum = add_ip_checksums(bytes, checksum, 
		compute_ip_checksum(phdr, ehdr->e_phnum*sizeof(*phdr)));
	bytes += ehdr->e_phnum*sizeof(*phdr);
	for(ptr = head->phdr_next; ptr != head; ptr = ptr->phdr_next) {
		checksum = add_ip_checksums(bytes, checksum,
			compute_ip_checksum((void *)ptr->s_addr, ptr->s_memsz));
		bytes += ptr->s_memsz;
	}
	if (n_desc != 0) {
		memcpy(n_desc, buff, 2);
	}
	if (checksum != cb->ip_checksum) {
		printk_err("Image checksum: %04x != computed checksum: %04x\n",
			cb->ip_checksum, checksum);
	}
	return checksum == cb->ip_checksum;
}

/* The problem:  
 * Static executables all want to share the same addresses
 * in memory because only a few addresses are reliably present on
 * a machine, and implementing general relocation is hard.
 *
 * The solution:
 * - Allocate a buffer twice the size of the coreboot image.
 * - Anything that would overwrite coreboot copy into the lower half of
 *   the buffer. 
 * - After loading an ELF image copy coreboot to the upper half of the
 *   buffer.
 * - Then jump to the loaded image.
 * 
 * Benefits:
 * - Nearly arbitrary standalone executables can be loaded.
 * - Coreboot is preserved, so it can be returned to.
 * - The implementation is still relatively simple,
 *   and much simpler then the general case implemented in kexec.
 * 
 */

static unsigned long get_bounce_buffer(struct lb_memory *mem)
{
	unsigned long lb_size;
	unsigned long mem_entries;
	unsigned long buffer;
	int i;
	lb_size = (unsigned long)(&_eram_seg - &_ram_seg);
	/* Double coreboot size so I have somewhere to place a copy to return to */
	lb_size = lb_size + lb_size;
	mem_entries = (mem->size - sizeof(*mem))/sizeof(mem->map[0]);
	buffer = 0;
	for(i = 0; i < mem_entries; i++) {
		unsigned long mstart, mend;
		unsigned long msize;
		unsigned long tbuffer;
		if (mem->map[i].type != LB_MEM_RAM)
			continue;
		if (unpack_lb64(mem->map[i].start) > MAX_ADDR)
			continue;
		if (unpack_lb64(mem->map[i].size) < lb_size)
			continue;
		mstart = unpack_lb64(mem->map[i].start);
		msize = MAX_ADDR - mstart +1;
		if (msize > unpack_lb64(mem->map[i].size))
			msize = unpack_lb64(mem->map[i].size);
		mend = mstart + msize;
		tbuffer = mend - lb_size;
		if (tbuffer < buffer) 
			continue;
		buffer = tbuffer;
	}
	return buffer;
}


static struct verify_callback *process_elf_notes(
	unsigned char *header, 
	unsigned long offset, unsigned long length)
{
	struct verify_callback *cb_chain;
	unsigned char *note, *end;
	unsigned char *program, *version;

	cb_chain = 0;
	note = header + offset;
	end = note + length;
	program = version = 0;
	while(note < end) {
		Elf_Nhdr *hdr;
		unsigned char *n_name, *n_desc, *next;
		hdr = (Elf_Nhdr *)note;
		n_name = note + sizeof(*hdr);
		n_desc = n_name + ((hdr->n_namesz + 3) & ~3);
		next = n_desc + ((hdr->n_descsz + 3) & ~3);
		if (next > end) {
			break;
		}
		if ((hdr->n_namesz == sizeof(ELF_NOTE_BOOT)) && 
			(memcmp(n_name, ELF_NOTE_BOOT, sizeof(ELF_NOTE_BOOT)) == 0)) {
			switch(hdr->n_type) {
			case EIN_PROGRAM_NAME:
				if (n_desc[hdr->n_descsz -1] == 0) {
					program = n_desc;
				}
				break;
			case EIN_PROGRAM_VERSION:
				if (n_desc[hdr->n_descsz -1] == 0) {
					version = n_desc;
				}
				break;
			case EIN_PROGRAM_CHECKSUM:
			{
				struct ip_checksum_vcb *cb;
				cb = malloc(sizeof(*cb));
				cb->ip_checksum = *((uint16_t *)n_desc);
				cb->data.callback = verify_ip_checksum;
				cb->data.next = cb_chain;
				cb->data.desc_offset = n_desc - header;
				cb_chain = &cb->data;
				break;
			}
			}
		}
		printk_spew("n_type: %08x n_name(%d): %-*.*s n_desc(%d): %-*.*s\n", 
			hdr->n_type,
			hdr->n_namesz, hdr->n_namesz, hdr->n_namesz, n_name,
			hdr->n_descsz,hdr->n_descsz, hdr->n_descsz, n_desc);
		note = next;
	}
	if (program && version) {
		printk_info("Loading %s version: %s\n",
			program, version);
	}
	return cb_chain;
}

static int valid_area(struct lb_memory *mem, unsigned long buffer,
	unsigned long start, unsigned long len)
{
	/* Check through all of the memory segments and ensure
	 * the segment that was passed in is completely contained
	 * in RAM.
	 */
	int i;
	unsigned long end = start + len;
	unsigned long mem_entries = (mem->size - sizeof(*mem))/sizeof(mem->map[0]);

	/* See if I conflict with the bounce buffer */
	if (end >= buffer) {
		return 0;
	}

	/* Walk through the table of valid memory ranges and see if I
	 * have a match.
	 */
	for(i = 0; i < mem_entries; i++) {
		uint64_t mstart, mend;
		uint32_t mtype;
		mtype = mem->map[i].type;
		mstart = unpack_lb64(mem->map[i].start);
		mend = mstart + unpack_lb64(mem->map[i].size);
		if ((mtype == LB_MEM_RAM) && (start < mend) && (end > mstart)) {
			break;
		}
	}
	if (i == mem_entries) {
		printk_err("No matching ram area found for range:\n");
		printk_err("  [0x%016lx, 0x%016lx)\n", start, end);
		printk_err("Ram areas\n");
		for(i = 0; i < mem_entries; i++) {
			uint64_t mstart, mend;
			uint32_t mtype;
			mtype = mem->map[i].type;
			mstart = unpack_lb64(mem->map[i].start);
			mend = mstart + unpack_lb64(mem->map[i].size);
			printk_err("  [0x%016lx, 0x%016lx) %s\n",
				(unsigned long)mstart, 
				(unsigned long)mend, 
				(mtype == LB_MEM_RAM)?"RAM":"Reserved");
			
		}
		return 0;
	}
	return 1;
}

static void relocate_segment(unsigned long buffer, struct segment *seg)
{
	/* Modify all segments that want to load onto coreboot
	 * to load onto the bounce buffer instead.
	 */
	unsigned long lb_start = (unsigned long)&_ram_seg;
	unsigned long lb_end = (unsigned long)&_eram_seg;
	unsigned long start, middle, end;

	printk_spew("lb: [0x%016lx, 0x%016lx)\n", 
		lb_start, lb_end);

	start = seg->s_addr;
	middle = start + seg->s_filesz;
	end = start + seg->s_memsz;
	/* I don't conflict with coreboot so get out of here */
	if ((end <= lb_start) || (start >= lb_end))
		return;

	printk_spew("segment: [0x%016lx, 0x%016lx, 0x%016lx)\n", 
		start, middle, end);

	/* Slice off a piece at the beginning
	 * that doesn't conflict with coreboot.
	 */
	if (start < lb_start) {
		struct segment *new;
		unsigned long len = lb_start - start;
		new = malloc(sizeof(*new));
		*new = *seg;
		new->s_memsz = len;
		seg->s_memsz -= len;
		seg->s_addr += len;
		seg->s_offset += len;
		if (seg->s_filesz > len) {
			new->s_filesz = len;
			seg->s_filesz -= len;
		} else {
			seg->s_filesz = 0;
		}

		/* Order by stream offset */
		new->next = seg;
		new->prev = seg->prev;
		seg->prev->next = new;
		seg->prev = new;
		/* Order by original program header order */
		new->phdr_next = seg;
		new->phdr_prev = seg->phdr_prev;
		seg->phdr_prev->phdr_next = new;
		seg->phdr_prev = new;

		/* compute the new value of start */
		start = seg->s_addr;
		
		printk_spew("   early: [0x%016lx, 0x%016lx, 0x%016lx)\n", 
			new->s_addr, 
			new->s_addr + new->s_filesz,
			new->s_addr + new->s_memsz);
	}
	
	/* Slice off a piece at the end 
	 * that doesn't conflict with coreboot 
	 */
	if (end > lb_end) {
		unsigned long len = lb_end - start;
		struct segment *new;
		new = malloc(sizeof(*new));
		*new = *seg;
		seg->s_memsz = len;
		new->s_memsz -= len;
		new->s_addr += len;
		new->s_offset += len;
		if (seg->s_filesz > len) {
			seg->s_filesz = len;
			new->s_filesz -= len;
		} else {
			new->s_filesz = 0;
		}
		/* Order by stream offset */
		new->next = seg->next;
		new->prev = seg;
		seg->next->prev = new;
		seg->next = new;
		/* Order by original program header order */
		new->phdr_next = seg->phdr_next;
		new->phdr_prev = seg;
		seg->phdr_next->phdr_prev = new;
		seg->phdr_next = new;

		/* compute the new value of end */
		end = start + len;
		
		printk_spew("   late: [0x%016lx, 0x%016lx, 0x%016lx)\n", 
			new->s_addr, 
			new->s_addr + new->s_filesz,
			new->s_addr + new->s_memsz);
		
	}
	/* Now retarget this segment onto the bounce buffer */
	seg->s_addr = buffer + (seg->s_addr - lb_start);

	printk_spew(" bounce: [0x%016lx, 0x%016lx, 0x%016lx)\n", 
		seg->s_addr, 
		seg->s_addr + seg->s_filesz, 
		seg->s_addr + seg->s_memsz);
}


static int build_elf_segment_list(
	struct segment *head, 
	unsigned long bounce_buffer, struct lb_memory *mem,
	Elf_phdr *phdr, int headers)
{
	struct segment *ptr;
	int i;
	memset(head, 0, sizeof(*head));
	head->phdr_next = head->phdr_prev = head;
	head->next = head->prev = head;
	for(i = 0; i < headers; i++) {
		struct segment *new;
		/* Ignore data that I don't need to handle */
		if (phdr[i].p_type != PT_LOAD) {
			printk_debug("Dropping non PT_LOAD segment\n");
			continue;
		}
		if (phdr[i].p_memsz == 0) {
			printk_debug("Dropping empty segment\n");
			continue;
		}
		new = malloc(sizeof(*new));
		new->s_addr = phdr[i].p_paddr;
		new->s_memsz = phdr[i].p_memsz;
		new->s_offset = phdr[i].p_offset;
		new->s_filesz = phdr[i].p_filesz;
		printk_debug("New segment addr 0x%lx size 0x%lx offset 0x%lx filesize 0x%lx\n",
			new->s_addr, new->s_memsz, new->s_offset, new->s_filesz);
		/* Clean up the values */
		if (new->s_filesz > new->s_memsz)  {
			new->s_filesz = new->s_memsz;
		}
		printk_debug("(cleaned up) New segment addr 0x%lx size 0x%lx offset 0x%lx filesize 0x%lx\n",
			new->s_addr, new->s_memsz, new->s_offset, new->s_filesz);
		for(ptr = head->next; ptr != head; ptr = ptr->next) {
			if (new->s_offset < ptr->s_offset)
				break;
		}
		/* Order by stream offset */
		new->next = ptr;
		new->prev = ptr->prev;
		ptr->prev->next = new;
		ptr->prev = new;
		/* Order by original program header order */
		new->phdr_next = head;
		new->phdr_prev = head->phdr_prev;
		head->phdr_prev->phdr_next  = new;
		head->phdr_prev = new;

		/* Verify the memory addresses in the segment are valid */
		if (!valid_area(mem, bounce_buffer, new->s_addr, new->s_memsz)) 
			goto out;

		/* Modify the segment to load onto the bounce_buffer if necessary.
		 */
		relocate_segment(bounce_buffer, new);
	}
	return 1;
 out:
	return 0;
}

static int load_elf_segments(
	struct segment *head, unsigned char *header, unsigned long header_size)
{
	unsigned long offset;
	struct segment *ptr;
	
	offset = 0;
	for(ptr = head->next; ptr != head; ptr = ptr->next) {
		unsigned long start_offset;
		unsigned long skip_bytes, read_bytes;
		unsigned char *dest, *middle, *end;
		byte_offset_t result;
		printk_debug("Loading Segment: addr: 0x%016lx memsz: 0x%016lx filesz: 0x%016lx\n",
			ptr->s_addr, ptr->s_memsz, ptr->s_filesz);
		
		/* Compute the boundaries of the segment */
		dest = (unsigned char *)(ptr->s_addr);
		end = dest + ptr->s_memsz;
		middle = dest + ptr->s_filesz;
		start_offset = ptr->s_offset;
		/* Ignore s_offset if I have a pure bss segment */
		if (ptr->s_filesz == 0) {
			start_offset = offset;
		}
		
		printk_spew("[ 0x%016lx, %016lx, 0x%016lx) <- %016lx\n",
			(unsigned long)dest,
			(unsigned long)middle,
			(unsigned long)end,
			(unsigned long)start_offset);
		
		/* Skip intial buffer unused bytes */
		if (offset < header_size) {
			if (start_offset < header_size) {
				offset = start_offset;
			} else {
				offset = header_size;
			}
		}
		
		/* Skip the unused bytes */
		skip_bytes = start_offset - offset;
		if (skip_bytes && 
			((result = stream_skip(skip_bytes)) != skip_bytes)) {
			printk_err("ERROR: Skip of %ld bytes skipped %ld bytes\n",
				skip_bytes, result);
			goto out;
		}
		offset = start_offset;
		
		/* Copy data from the initial buffer */
		if (offset < header_size) {
			size_t len;
			if ((ptr->s_filesz + start_offset) > header_size) {
				len = header_size - start_offset;
			}
			else {
				len = ptr->s_filesz;
			}
			memcpy(dest, &header[start_offset], len);
			dest += len;
		}
		
		/* Read the segment into memory */
		read_bytes = middle - dest;
		if (read_bytes && 
			((result = stream_read(dest, read_bytes)) != read_bytes)) {
			printk_err("ERROR: Read of %ld bytes read %ld bytes...\n",
				read_bytes, result);
			goto out;
		}
		offset += ptr->s_filesz;
		
		/* Zero the extra bytes between middle & end */
		if (middle < end) {
			printk_debug("Clearing Segment: addr: 0x%016lx memsz: 0x%016lx\n",
				(unsigned long)middle, end - middle);
			
			/* Zero the extra bytes */
			memset(middle, 0, end - middle);
		}
	}
	return 1;
 out:
	return 0;
}

static int verify_loaded_image(
	struct verify_callback *vcb,
	Elf_ehdr *ehdr, Elf_phdr *phdr,
	struct segment *head
	)
{
	struct segment *ptr;
	int ok;
	ok = 1;
	for(; ok && vcb ; vcb = vcb->next) {
		/* Find where the note is loaded */
		/* The whole note must be loaded intact
		 * so an address of 0 for the descriptor is impossible
		 */
		vcb->desc_addr = 0; 
		for(ptr = head->next; ptr != head; ptr = ptr->next) {
			unsigned long desc_addr;
			desc_addr = ptr->s_addr + vcb->desc_offset - ptr->s_offset;
			if ((desc_addr >= ptr->s_addr) &&
				(desc_addr < (ptr->s_addr + ptr->s_filesz))) {
				vcb->desc_addr = desc_addr;
			}
		}
		ok = vcb->callback(vcb, ehdr, phdr, head);
	}
	return ok;
}

int elfload(struct lb_memory *mem,
	unsigned char *header, unsigned long header_size)
{
	Elf_ehdr *ehdr;
	Elf_phdr *phdr;
	void *entry;
	struct segment head;
	struct verify_callback *cb_chain;
	unsigned long bounce_buffer;

	/* Find a bounce buffer so I can load to coreboot's current location */
	bounce_buffer = get_bounce_buffer(mem);
	if (!bounce_buffer) {
		printk_err("Could not find a bounce buffer...\n");
		goto out;
	}

	ehdr = (Elf_ehdr *)header;
	entry = (void *)(ehdr->e_entry);
	phdr = (Elf_phdr *)(&header[ehdr->e_phoff]);

	/* Digest elf note information... */
	cb_chain = 0;
	if ((phdr[0].p_type == PT_NOTE) && 
		((phdr[0].p_offset + phdr[0].p_filesz) < header_size)) {
		cb_chain = process_elf_notes(header,
			phdr[0].p_offset, phdr[0].p_filesz);
	}

	/* Preprocess the elf segments */
	if (!build_elf_segment_list(&head, 
		bounce_buffer, mem, phdr, ehdr->e_phnum))
		goto out;

	/* Load the segments */
	if (!load_elf_segments(&head, header, header_size))
		goto out;

	printk_spew("Loaded segments\n");
	/* Verify the loaded image */
	if (!verify_loaded_image(cb_chain, ehdr, phdr, &head)) 
		goto out;

	printk_spew("verified segments\n");
	/* Shutdown the stream device */
	stream_fini();
	
	printk_spew("closed down stream\n");
	/* Reset to booting from this image as late as possible */
	boot_successful();

	printk_debug("Jumping to boot code at 0x%x\n", entry);
	post_code(0xfe);

	/* Jump to kernel */
	jmp_to_elf_entry(entry, bounce_buffer);
	return 1;

 out:
	return 0;
}

int elfboot(struct lb_memory *mem)
{
	Elf_ehdr *ehdr;
	static unsigned char header[ELF_HEAD_SIZE];
	int header_offset;
	int i, result;

	result = 0;
	printk_info("\n");
	printk_info("Welcome to %s, the open sourced starter.\n", BOOTLOADER);
	printk_info("January 2002, Eric Biederman.\n");
	printk_info("Version %s\n", BOOTLOADER_VERSION);
	printk_info("\n");
	post_code(0xf8);

	if (stream_init() < 0) {
		printk_err("Could not initialize driver...\n");
		goto out;
	}

	/* Read in the initial ELF_HEAD_SIZE bytes */
	if (stream_read(header, ELF_HEAD_SIZE) != ELF_HEAD_SIZE) {
		printk_err("Read failed...\n");
		goto out;
	}
	/* Scan for an elf header */
	header_offset = -1;
	for(i = 0; i < ELF_HEAD_SIZE - (sizeof(Elf_ehdr) + sizeof(Elf_phdr)); i+=16) {
		ehdr = (Elf_ehdr *)(&header[i]);
		if (memcmp(ehdr->e_ident, ELFMAG, 4) != 0) {
			printk_debug("No header at %d\n", i);
			continue;
		}
		printk_debug("Found ELF candidate at offset %d\n", i);
		/* Sanity check the elf header */
		if ((ehdr->e_type == ET_EXEC) &&
			elf_check_arch(ehdr) &&
			(ehdr->e_ident[EI_VERSION] == EV_CURRENT) &&
			(ehdr->e_version == EV_CURRENT) &&
			(ehdr->e_ehsize == sizeof(Elf_ehdr)) &&
			(ehdr->e_phentsize = sizeof(Elf_phdr)) &&
			(ehdr->e_phoff < (ELF_HEAD_SIZE - i)) &&
			((ehdr->e_phoff + (ehdr->e_phentsize * ehdr->e_phnum)) <= 
				(ELF_HEAD_SIZE - i))) {
			header_offset = i;
			break;
		}
		ehdr = 0;
	}
	printk_debug("header_offset is %d\n", header_offset);
	if (header_offset == -1) {
		goto out;
	}

	printk_debug("Try to load at offset 0x%x\n", header_offset);
	result = elfload(mem, 
		header + header_offset , ELF_HEAD_SIZE - header_offset);
 out:
	if (!result) {
		/* Shutdown the stream device */
		stream_fini();

		printk_err("Can not load ELF Image.\n");

		post_code(0xff);
	}
	return 0;

}