summaryrefslogtreecommitdiff
path: root/arch/x86/tools/relocs.c
blob: b8f7c65fc40c8559fc3412ff0240c9573ece3196 (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
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <elf.h>
#include <byteswap.h>
#define USE_BSD
#include <endian.h>
#include <regex.h>
#include <tools/le_byteshift.h>

static void die(char *fmt, ...);

#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
static Elf32_Ehdr ehdr;
static unsigned long reloc_count, reloc_idx;
static unsigned long *relocs;
static unsigned long reloc16_count, reloc16_idx;
static unsigned long *relocs16;

struct section {
	Elf32_Shdr     shdr;
	struct section *link;
	Elf32_Sym      *symtab;
	Elf32_Rel      *reltab;
	char           *strtab;
};
static struct section *secs;

enum symtype {
	S_ABS,
	S_REL,
	S_SEG,
	S_LIN,
	S_NSYMTYPES
};

static const char * const sym_regex_kernel[S_NSYMTYPES] = {
/*
 * Following symbols have been audited. There values are constant and do
 * not change if bzImage is loaded at a different physical address than
 * the address for which it has been compiled. Don't warn user about
 * absolute relocations present w.r.t these symbols.
 */
	[S_ABS] =
	"^(xen_irq_disable_direct_reloc$|"
	"xen_save_fl_direct_reloc$|"
	"VDSO|"
	"__crc_)",

/*
 * These symbols are known to be relative, even if the linker marks them
 * as absolute (typically defined outside any section in the linker script.)
 */
	[S_REL] =
	"^(__init_(begin|end)|"
	"__x86_cpu_dev_(start|end)|"
	"(__parainstructions|__alt_instructions)(|_end)|"
	"(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
	"__(start|end)_pci_.*|"
	"__(start|end)_builtin_fw|"
	"__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
	"__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
	"__(start|stop)___param|"
	"__(start|stop)___modver|"
	"__(start|stop)___bug_table|"
	"__tracedata_(start|end)|"
	"__(start|stop)_notes|"
	"__end_rodata|"
	"__initramfs_start|"
	"_end)$"
};


static const char * const sym_regex_realmode[S_NSYMTYPES] = {
/*
 * These are 16-bit segment symbols when compiling 16-bit code.
 */
	[S_SEG] =
	"^real_mode_seg$",

/*
 * These are offsets belonging to segments, as opposed to linear addresses,
 * when compiling 16-bit code.
 */
	[S_LIN] =
	"^pa_",
};

static const char * const *sym_regex;

static regex_t sym_regex_c[S_NSYMTYPES];
static int is_reloc(enum symtype type, const char *sym_name)
{
	return sym_regex[type] &&
		!regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
}

static void regex_init(int use_real_mode)
{
        char errbuf[128];
        int err;
	int i;

	if (use_real_mode)
		sym_regex = sym_regex_realmode;
	else
		sym_regex = sym_regex_kernel;

	for (i = 0; i < S_NSYMTYPES; i++) {
		if (!sym_regex[i])
			continue;

		err = regcomp(&sym_regex_c[i], sym_regex[i],
			      REG_EXTENDED|REG_NOSUB);

		if (err) {
			regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
			die("%s", errbuf);
		}
        }
}

static void die(char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	exit(1);
}

static const char *sym_type(unsigned type)
{
	static const char *type_name[] = {
#define SYM_TYPE(X) [X] = #X
		SYM_TYPE(STT_NOTYPE),
		SYM_TYPE(STT_OBJECT),
		SYM_TYPE(STT_FUNC),
		SYM_TYPE(STT_SECTION),
		SYM_TYPE(STT_FILE),
		SYM_TYPE(STT_COMMON),
		SYM_TYPE(STT_TLS),
#undef SYM_TYPE
	};
	const char *name = "unknown sym type name";
	if (type < ARRAY_SIZE(type_name)) {
		name = type_name[type];
	}
	return name;
}

static const char *sym_bind(unsigned bind)
{
	static const char *bind_name[] = {
#define SYM_BIND(X) [X] = #X
		SYM_BIND(STB_LOCAL),
		SYM_BIND(STB_GLOBAL),
		SYM_BIND(STB_WEAK),
#undef SYM_BIND
	};
	const char *name = "unknown sym bind name";
	if (bind < ARRAY_SIZE(bind_name)) {
		name = bind_name[bind];
	}
	return name;
}

static const char *sym_visibility(unsigned visibility)
{
	static const char *visibility_name[] = {
#define SYM_VISIBILITY(X) [X] = #X
		SYM_VISIBILITY(STV_DEFAULT),
		SYM_VISIBILITY(STV_INTERNAL),
		SYM_VISIBILITY(STV_HIDDEN),
		SYM_VISIBILITY(STV_PROTECTED),
#undef SYM_VISIBILITY
	};
	const char *name = "unknown sym visibility name";
	if (visibility < ARRAY_SIZE(visibility_name)) {
		name = visibility_name[visibility];
	}
	return name;
}

static const char *rel_type(unsigned type)
{
	static const char *type_name[] = {
#define REL_TYPE(X) [X] = #X
		REL_TYPE(R_386_NONE),
		REL_TYPE(R_386_32),
		REL_TYPE(R_386_PC32),
		REL_TYPE(R_386_GOT32),
		REL_TYPE(R_386_PLT32),
		REL_TYPE(R_386_COPY),
		REL_TYPE(R_386_GLOB_DAT),
		REL_TYPE(R_386_JMP_SLOT),
		REL_TYPE(R_386_RELATIVE),
		REL_TYPE(R_386_GOTOFF),
		REL_TYPE(R_386_GOTPC),
		REL_TYPE(R_386_8),
		REL_TYPE(R_386_PC8),
		REL_TYPE(R_386_16),
		REL_TYPE(R_386_PC16),
#undef REL_TYPE
	};
	const char *name = "unknown type rel type name";
	if (type < ARRAY_SIZE(type_name) && type_name[type]) {
		name = type_name[type];
	}
	return name;
}

static const char *sec_name(unsigned shndx)
{
	const char *sec_strtab;
	const char *name;
	sec_strtab = secs[ehdr.e_shstrndx].strtab;
	name = "<noname>";
	if (shndx < ehdr.e_shnum) {
		name = sec_strtab + secs[shndx].shdr.sh_name;
	}
	else if (shndx == SHN_ABS) {
		name = "ABSOLUTE";
	}
	else if (shndx == SHN_COMMON) {
		name = "COMMON";
	}
	return name;
}

static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
{
	const char *name;
	name = "<noname>";
	if (sym->st_name) {
		name = sym_strtab + sym->st_name;
	}
	else {
		name = sec_name(sym->st_shndx);
	}
	return name;
}



#if BYTE_ORDER == LITTLE_ENDIAN
#define le16_to_cpu(val) (val)
#define le32_to_cpu(val) (val)
#endif
#if BYTE_ORDER == BIG_ENDIAN
#define le16_to_cpu(val) bswap_16(val)
#define le32_to_cpu(val) bswap_32(val)
#endif

static uint16_t elf16_to_cpu(uint16_t val)
{
	return le16_to_cpu(val);
}

static uint32_t elf32_to_cpu(uint32_t val)
{
	return le32_to_cpu(val);
}

static void read_ehdr(FILE *fp)
{
	if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
		die("Cannot read ELF header: %s\n",
			strerror(errno));
	}
	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
		die("No ELF magic\n");
	}
	if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
		die("Not a 32 bit executable\n");
	}
	if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
		die("Not a LSB ELF executable\n");
	}
	if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
		die("Unknown ELF version\n");
	}
	/* Convert the fields to native endian */
	ehdr.e_type      = elf16_to_cpu(ehdr.e_type);
	ehdr.e_machine   = elf16_to_cpu(ehdr.e_machine);
	ehdr.e_version   = elf32_to_cpu(ehdr.e_version);
	ehdr.e_entry     = elf32_to_cpu(ehdr.e_entry);
	ehdr.e_phoff     = elf32_to_cpu(ehdr.e_phoff);
	ehdr.e_shoff     = elf32_to_cpu(ehdr.e_shoff);
	ehdr.e_flags     = elf32_to_cpu(ehdr.e_flags);
	ehdr.e_ehsize    = elf16_to_cpu(ehdr.e_ehsize);
	ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
	ehdr.e_phnum     = elf16_to_cpu(ehdr.e_phnum);
	ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
	ehdr.e_shnum     = elf16_to_cpu(ehdr.e_shnum);
	ehdr.e_shstrndx  = elf16_to_cpu(ehdr.e_shstrndx);

	if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
		die("Unsupported ELF header type\n");
	}
	if (ehdr.e_machine != EM_386) {
		die("Not for x86\n");
	}
	if (ehdr.e_version != EV_CURRENT) {
		die("Unknown ELF version\n");
	}
	if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
		die("Bad Elf header size\n");
	}
	if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
		die("Bad program header entry\n");
	}
	if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
		die("Bad section header entry\n");
	}
	if (ehdr.e_shstrndx >= ehdr.e_shnum) {
		die("String table index out of bounds\n");
	}
}

static void read_shdrs(FILE *fp)
{
	int i;
	Elf32_Shdr shdr;

	secs = calloc(ehdr.e_shnum, sizeof(struct section));
	if (!secs) {
		die("Unable to allocate %d section headers\n",
		    ehdr.e_shnum);
	}
	if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
		die("Seek to %d failed: %s\n",
			ehdr.e_shoff, strerror(errno));
	}
	for (i = 0; i < ehdr.e_shnum; i++) {
		struct section *sec = &secs[i];
		if (fread(&shdr, sizeof shdr, 1, fp) != 1)
			die("Cannot read ELF section headers %d/%d: %s\n",
			    i, ehdr.e_shnum, strerror(errno));
		sec->shdr.sh_name      = elf32_to_cpu(shdr.sh_name);
		sec->shdr.sh_type      = elf32_to_cpu(shdr.sh_type);
		sec->shdr.sh_flags     = elf32_to_cpu(shdr.sh_flags);
		sec->shdr.sh_addr      = elf32_to_cpu(shdr.sh_addr);
		sec->shdr.sh_offset    = elf32_to_cpu(shdr.sh_offset);
		sec->shdr.sh_size      = elf32_to_cpu(shdr.sh_size);
		sec->shdr.sh_link      = elf32_to_cpu(shdr.sh_link);
		sec->shdr.sh_info      = elf32_to_cpu(shdr.sh_info);
		sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign);
		sec->shdr.sh_entsize   = elf32_to_cpu(shdr.sh_entsize);
		if (sec->shdr.sh_link < ehdr.e_shnum)
			sec->link = &secs[sec->shdr.sh_link];
	}

}

static void read_strtabs(FILE *fp)
{
	int i;
	for (i = 0; i < ehdr.e_shnum; i++) {
		struct section *sec = &secs[i];
		if (sec->shdr.sh_type != SHT_STRTAB) {
			continue;
		}
		sec->strtab = malloc(sec->shdr.sh_size);
		if (!sec->strtab) {
			die("malloc of %d bytes for strtab failed\n",
				sec->shdr.sh_size);
		}
		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
			die("Seek to %d failed: %s\n",
				sec->shdr.sh_offset, strerror(errno));
		}
		if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
		    != sec->shdr.sh_size) {
			die("Cannot read symbol table: %s\n",
				strerror(errno));
		}
	}
}

static void read_symtabs(FILE *fp)
{
	int i,j;
	for (i = 0; i < ehdr.e_shnum; i++) {
		struct section *sec = &secs[i];
		if (sec->shdr.sh_type != SHT_SYMTAB) {
			continue;
		}
		sec->symtab = malloc(sec->shdr.sh_size);
		if (!sec->symtab) {
			die("malloc of %d bytes for symtab failed\n",
				sec->shdr.sh_size);
		}
		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
			die("Seek to %d failed: %s\n",
				sec->shdr.sh_offset, strerror(errno));
		}
		if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
		    != sec->shdr.sh_size) {
			die("Cannot read symbol table: %s\n",
				strerror(errno));
		}
		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
			Elf32_Sym *sym = &sec->symtab[j];
			sym->st_name  = elf32_to_cpu(sym->st_name);
			sym->st_value = elf32_to_cpu(sym->st_value);
			sym->st_size  = elf32_to_cpu(sym->st_size);
			sym->st_shndx = elf16_to_cpu(sym->st_shndx);
		}
	}
}


static void read_relocs(FILE *fp)
{
	int i,j;
	for (i = 0; i < ehdr.e_shnum; i++) {
		struct section *sec = &secs[i];
		if (sec->shdr.sh_type != SHT_REL) {
			continue;
		}
		sec->reltab = malloc(sec->shdr.sh_size);
		if (!sec->reltab) {
			die("malloc of %d bytes for relocs failed\n",
				sec->shdr.sh_size);
		}
		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
			die("Seek to %d failed: %s\n",
				sec->shdr.sh_offset, strerror(errno));
		}
		if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
		    != sec->shdr.sh_size) {
			die("Cannot read symbol table: %s\n",
				strerror(errno));
		}
		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
			Elf32_Rel *rel = &sec->reltab[j];
			rel->r_offset = elf32_to_cpu(rel->r_offset);
			rel->r_info   = elf32_to_cpu(rel->r_info);
		}
	}
}


static void print_absolute_symbols(void)
{
	int i;
	printf("Absolute symbols\n");
	printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
	for (i = 0; i < ehdr.e_shnum; i++) {
		struct section *sec = &secs[i];
		char *sym_strtab;
		int j;

		if (sec->shdr.sh_type != SHT_SYMTAB) {
			continue;
		}
		sym_strtab = sec->link->strtab;
		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
			Elf32_Sym *sym;
			const char *name;
			sym = &sec->symtab[j];
			name = sym_name(sym_strtab, sym);
			if (sym->st_shndx != SHN_ABS) {
				continue;
			}
			printf("%5d %08x %5d %10s %10s %12s %s\n",
				j, sym->st_value, sym->st_size,
				sym_type(ELF32_ST_TYPE(sym->st_info)),
				sym_bind(ELF32_ST_BIND(sym->st_info)),
				sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
				name);
		}
	}
	printf("\n");
}

static void print_absolute_relocs(void)
{
	int i, printed = 0;

	for (i = 0; i < ehdr.e_shnum; i++) {
		struct section *sec = &secs[i];
		struct section *sec_applies, *sec_symtab;
		char *sym_strtab;
		Elf32_Sym *sh_symtab;
		int j;
		if (sec->shdr.sh_type != SHT_REL) {
			continue;
		}
		sec_symtab  = sec->link;
		sec_applies = &secs[sec->shdr.sh_info];
		if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
			continue;
		}
		sh_symtab  = sec_symtab->symtab;
		sym_strtab = sec_symtab->link->strtab;
		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
			Elf32_Rel *rel;
			Elf32_Sym *sym;
			const char *name;
			rel = &sec->reltab[j];
			sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
			name = sym_name(sym_strtab, sym);
			if (sym->st_shndx != SHN_ABS) {
				continue;
			}

			/* Absolute symbols are not relocated if bzImage is
			 * loaded at a non-compiled address. Display a warning
			 * to user at compile time about the absolute
			 * relocations present.
			 *
			 * User need to audit the code to make sure
			 * some symbols which should have been section
			 * relative have not become absolute because of some
			 * linker optimization or wrong programming usage.
			 *
			 * Before warning check if this absolute symbol
			 * relocation is harmless.
			 */
			if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
				continue;

			if (!printed) {
				printf("WARNING: Absolute relocations"
					" present\n");
				printf("Offset     Info     Type     Sym.Value "
					"Sym.Name\n");
				printed = 1;
			}

			printf("%08x %08x %10s %08x  %s\n",
				rel->r_offset,
				rel->r_info,
				rel_type(ELF32_R_TYPE(rel->r_info)),
				sym->st_value,
				name);
		}
	}

	if (printed)
		printf("\n");
}

static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
			int use_real_mode)
{
	int i;
	/* Walk through the relocations */
	for (i = 0; i < ehdr.e_shnum; i++) {
		char *sym_strtab;
		Elf32_Sym *sh_symtab;
		struct section *sec_applies, *sec_symtab;
		int j;
		struct section *sec = &secs[i];

		if (sec->shdr.sh_type != SHT_REL) {
			continue;
		}
		sec_symtab  = sec->link;
		sec_applies = &secs[sec->shdr.sh_info];
		if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
			continue;
		}
		sh_symtab = sec_symtab->symtab;
		sym_strtab = sec_symtab->link->strtab;
		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
			Elf32_Rel *rel;
			Elf32_Sym *sym;
			unsigned r_type;
			const char *symname;
			int shn_abs;

			rel = &sec->reltab[j];
			sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
			r_type = ELF32_R_TYPE(rel->r_info);

			shn_abs = sym->st_shndx == SHN_ABS;

			switch (r_type) {
			case R_386_NONE:
			case R_386_PC32:
			case R_386_PC16:
			case R_386_PC8:
				/*
				 * NONE can be ignored and and PC relative
				 * relocations don't need to be adjusted.
				 */
				break;

			case R_386_16:
				symname = sym_name(sym_strtab, sym);
				if (!use_real_mode)
					goto bad;
				if (shn_abs) {
					if (is_reloc(S_ABS, symname))
						break;
					else if (!is_reloc(S_SEG, symname))
						goto bad;
				} else {
					if (is_reloc(S_LIN, symname))
						goto bad;
					else
						break;
				}
				visit(rel, sym);
				break;

			case R_386_32:
				symname = sym_name(sym_strtab, sym);
				if (shn_abs) {
					if (is_reloc(S_ABS, symname))
						break;
					else if (!is_reloc(S_REL, symname))
						goto bad;
				} else {
					if (use_real_mode &&
					    !is_reloc(S_LIN, symname))
						break;
				}
				visit(rel, sym);
				break;
			default:
				die("Unsupported relocation type: %s (%d)\n",
				    rel_type(r_type), r_type);
				break;
			bad:
				symname = sym_name(sym_strtab, sym);
				die("Invalid %s %s relocation: %s\n",
				    shn_abs ? "absolute" : "relative",
				    rel_type(r_type), symname);
			}
		}
	}
}

static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
	if (ELF32_R_TYPE(rel->r_info) == R_386_16)
		reloc16_count++;
	else
		reloc_count++;
}

static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
	/* Remember the address that needs to be adjusted. */
	if (ELF32_R_TYPE(rel->r_info) == R_386_16)
		relocs16[reloc16_idx++] = rel->r_offset;
	else
		relocs[reloc_idx++] = rel->r_offset;
}

static int cmp_relocs(const void *va, const void *vb)
{
	const unsigned long *a, *b;
	a = va; b = vb;
	return (*a == *b)? 0 : (*a > *b)? 1 : -1;
}

static int write32(unsigned int v, FILE *f)
{
	unsigned char buf[4];

	put_unaligned_le32(v, buf);
	return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
}

static void emit_relocs(int as_text, int use_real_mode)
{
	int i;
	/* Count how many relocations I have and allocate space for them. */
	reloc_count = 0;
	walk_relocs(count_reloc, use_real_mode);
	relocs = malloc(reloc_count * sizeof(relocs[0]));
	if (!relocs) {
		die("malloc of %d entries for relocs failed\n",
			reloc_count);
	}

	relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
	if (!relocs16) {
		die("malloc of %d entries for relocs16 failed\n",
			reloc16_count);
	}
	/* Collect up the relocations */
	reloc_idx = 0;
	walk_relocs(collect_reloc, use_real_mode);

	if (reloc16_count && !use_real_mode)
		die("Segment relocations found but --realmode not specified\n");

	/* Order the relocations for more efficient processing */
	qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
	qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);

	/* Print the relocations */
	if (as_text) {
		/* Print the relocations in a form suitable that
		 * gas will like.
		 */
		printf(".section \".data.reloc\",\"a\"\n");
		printf(".balign 4\n");
		if (use_real_mode) {
			printf("\t.long %lu\n", reloc16_count);
			for (i = 0; i < reloc16_count; i++)
				printf("\t.long 0x%08lx\n", relocs16[i]);
			printf("\t.long %lu\n", reloc_count);
			for (i = 0; i < reloc_count; i++) {
				printf("\t.long 0x%08lx\n", relocs[i]);
			}
		} else {
			/* Print a stop */
			printf("\t.long 0x%08lx\n", (unsigned long)0);
			for (i = 0; i < reloc_count; i++) {
				printf("\t.long 0x%08lx\n", relocs[i]);
			}
		}

		printf("\n");
	}
	else {
		if (use_real_mode) {
			write32(reloc16_count, stdout);
			for (i = 0; i < reloc16_count; i++)
				write32(relocs16[i], stdout);
			write32(reloc_count, stdout);

			/* Now print each relocation */
			for (i = 0; i < reloc_count; i++)
				write32(relocs[i], stdout);
		} else {
			/* Print a stop */
			write32(0, stdout);

			/* Now print each relocation */
			for (i = 0; i < reloc_count; i++) {
				write32(relocs[i], stdout);
			}
		}
	}
}

static void usage(void)
{
	die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
}

int main(int argc, char **argv)
{
	int show_absolute_syms, show_absolute_relocs;
	int as_text, use_real_mode;
	const char *fname;
	FILE *fp;
	int i;

	show_absolute_syms = 0;
	show_absolute_relocs = 0;
	as_text = 0;
	use_real_mode = 0;
	fname = NULL;
	for (i = 1; i < argc; i++) {
		char *arg = argv[i];
		if (*arg == '-') {
			if (strcmp(arg, "--abs-syms") == 0) {
				show_absolute_syms = 1;
				continue;
			}
			if (strcmp(arg, "--abs-relocs") == 0) {
				show_absolute_relocs = 1;
				continue;
			}
			if (strcmp(arg, "--text") == 0) {
				as_text = 1;
				continue;
			}
			if (strcmp(arg, "--realmode") == 0) {
				use_real_mode = 1;
				continue;
			}
		}
		else if (!fname) {
			fname = arg;
			continue;
		}
		usage();
	}
	if (!fname) {
		usage();
	}
	regex_init(use_real_mode);
	fp = fopen(fname, "r");
	if (!fp) {
		die("Cannot open %s: %s\n",
			fname, strerror(errno));
	}
	read_ehdr(fp);
	read_shdrs(fp);
	read_strtabs(fp);
	read_symtabs(fp);
	read_relocs(fp);
	if (show_absolute_syms) {
		print_absolute_symbols();
		return 0;
	}
	if (show_absolute_relocs) {
		print_absolute_relocs();
		return 0;
	}
	emit_relocs(as_text, use_real_mode);
	return 0;
}