xref: /openbmc/linux/arch/x86/tools/relocs.c (revision a3e854d9)
1 #include <stdio.h>
2 #include <stdarg.h>
3 #include <stdlib.h>
4 #include <stdint.h>
5 #include <string.h>
6 #include <errno.h>
7 #include <unistd.h>
8 #include <elf.h>
9 #include <byteswap.h>
10 #define USE_BSD
11 #include <endian.h>
12 #include <regex.h>
13 #include <tools/le_byteshift.h>
14 
15 static void die(char *fmt, ...);
16 
17 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
18 static Elf32_Ehdr ehdr;
19 static unsigned long reloc_count, reloc_idx;
20 static unsigned long *relocs;
21 static unsigned long reloc16_count, reloc16_idx;
22 static unsigned long *relocs16;
23 
24 struct section {
25 	Elf32_Shdr     shdr;
26 	struct section *link;
27 	Elf32_Sym      *symtab;
28 	Elf32_Rel      *reltab;
29 	char           *strtab;
30 };
31 static struct section *secs;
32 
33 enum symtype {
34 	S_ABS,
35 	S_REL,
36 	S_SEG,
37 	S_LIN,
38 	S_NSYMTYPES
39 };
40 
41 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
42 /*
43  * Following symbols have been audited. There values are constant and do
44  * not change if bzImage is loaded at a different physical address than
45  * the address for which it has been compiled. Don't warn user about
46  * absolute relocations present w.r.t these symbols.
47  */
48 	[S_ABS] =
49 	"^(xen_irq_disable_direct_reloc$|"
50 	"xen_save_fl_direct_reloc$|"
51 	"VDSO|"
52 	"__crc_)",
53 
54 /*
55  * These symbols are known to be relative, even if the linker marks them
56  * as absolute (typically defined outside any section in the linker script.)
57  */
58 	[S_REL] =
59 	"^(__init_(begin|end)|"
60 	"__x86_cpu_dev_(start|end)|"
61 	"(__parainstructions|__alt_instructions)(|_end)|"
62 	"(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
63 	"_end)$"
64 };
65 
66 
67 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
68 /*
69  * These are 16-bit segment symbols when compiling 16-bit code.
70  */
71 	[S_SEG] =
72 	"^real_mode_seg$",
73 
74 /*
75  * These are offsets belonging to segments, as opposed to linear addresses,
76  * when compiling 16-bit code.
77  */
78 	[S_LIN] =
79 	"^pa_",
80 };
81 
82 static const char * const *sym_regex;
83 
84 static regex_t sym_regex_c[S_NSYMTYPES];
85 static int is_reloc(enum symtype type, const char *sym_name)
86 {
87 	return sym_regex[type] &&
88 		!regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
89 }
90 
91 static void regex_init(int use_real_mode)
92 {
93         char errbuf[128];
94         int err;
95 	int i;
96 
97 	if (use_real_mode)
98 		sym_regex = sym_regex_realmode;
99 	else
100 		sym_regex = sym_regex_kernel;
101 
102 	for (i = 0; i < S_NSYMTYPES; i++) {
103 		if (!sym_regex[i])
104 			continue;
105 
106 		err = regcomp(&sym_regex_c[i], sym_regex[i],
107 			      REG_EXTENDED|REG_NOSUB);
108 
109 		if (err) {
110 			regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
111 			die("%s", errbuf);
112 		}
113         }
114 }
115 
116 static void die(char *fmt, ...)
117 {
118 	va_list ap;
119 	va_start(ap, fmt);
120 	vfprintf(stderr, fmt, ap);
121 	va_end(ap);
122 	exit(1);
123 }
124 
125 static const char *sym_type(unsigned type)
126 {
127 	static const char *type_name[] = {
128 #define SYM_TYPE(X) [X] = #X
129 		SYM_TYPE(STT_NOTYPE),
130 		SYM_TYPE(STT_OBJECT),
131 		SYM_TYPE(STT_FUNC),
132 		SYM_TYPE(STT_SECTION),
133 		SYM_TYPE(STT_FILE),
134 		SYM_TYPE(STT_COMMON),
135 		SYM_TYPE(STT_TLS),
136 #undef SYM_TYPE
137 	};
138 	const char *name = "unknown sym type name";
139 	if (type < ARRAY_SIZE(type_name)) {
140 		name = type_name[type];
141 	}
142 	return name;
143 }
144 
145 static const char *sym_bind(unsigned bind)
146 {
147 	static const char *bind_name[] = {
148 #define SYM_BIND(X) [X] = #X
149 		SYM_BIND(STB_LOCAL),
150 		SYM_BIND(STB_GLOBAL),
151 		SYM_BIND(STB_WEAK),
152 #undef SYM_BIND
153 	};
154 	const char *name = "unknown sym bind name";
155 	if (bind < ARRAY_SIZE(bind_name)) {
156 		name = bind_name[bind];
157 	}
158 	return name;
159 }
160 
161 static const char *sym_visibility(unsigned visibility)
162 {
163 	static const char *visibility_name[] = {
164 #define SYM_VISIBILITY(X) [X] = #X
165 		SYM_VISIBILITY(STV_DEFAULT),
166 		SYM_VISIBILITY(STV_INTERNAL),
167 		SYM_VISIBILITY(STV_HIDDEN),
168 		SYM_VISIBILITY(STV_PROTECTED),
169 #undef SYM_VISIBILITY
170 	};
171 	const char *name = "unknown sym visibility name";
172 	if (visibility < ARRAY_SIZE(visibility_name)) {
173 		name = visibility_name[visibility];
174 	}
175 	return name;
176 }
177 
178 static const char *rel_type(unsigned type)
179 {
180 	static const char *type_name[] = {
181 #define REL_TYPE(X) [X] = #X
182 		REL_TYPE(R_386_NONE),
183 		REL_TYPE(R_386_32),
184 		REL_TYPE(R_386_PC32),
185 		REL_TYPE(R_386_GOT32),
186 		REL_TYPE(R_386_PLT32),
187 		REL_TYPE(R_386_COPY),
188 		REL_TYPE(R_386_GLOB_DAT),
189 		REL_TYPE(R_386_JMP_SLOT),
190 		REL_TYPE(R_386_RELATIVE),
191 		REL_TYPE(R_386_GOTOFF),
192 		REL_TYPE(R_386_GOTPC),
193 		REL_TYPE(R_386_8),
194 		REL_TYPE(R_386_PC8),
195 		REL_TYPE(R_386_16),
196 		REL_TYPE(R_386_PC16),
197 #undef REL_TYPE
198 	};
199 	const char *name = "unknown type rel type name";
200 	if (type < ARRAY_SIZE(type_name) && type_name[type]) {
201 		name = type_name[type];
202 	}
203 	return name;
204 }
205 
206 static const char *sec_name(unsigned shndx)
207 {
208 	const char *sec_strtab;
209 	const char *name;
210 	sec_strtab = secs[ehdr.e_shstrndx].strtab;
211 	name = "<noname>";
212 	if (shndx < ehdr.e_shnum) {
213 		name = sec_strtab + secs[shndx].shdr.sh_name;
214 	}
215 	else if (shndx == SHN_ABS) {
216 		name = "ABSOLUTE";
217 	}
218 	else if (shndx == SHN_COMMON) {
219 		name = "COMMON";
220 	}
221 	return name;
222 }
223 
224 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
225 {
226 	const char *name;
227 	name = "<noname>";
228 	if (sym->st_name) {
229 		name = sym_strtab + sym->st_name;
230 	}
231 	else {
232 		name = sec_name(sym->st_shndx);
233 	}
234 	return name;
235 }
236 
237 
238 
239 #if BYTE_ORDER == LITTLE_ENDIAN
240 #define le16_to_cpu(val) (val)
241 #define le32_to_cpu(val) (val)
242 #endif
243 #if BYTE_ORDER == BIG_ENDIAN
244 #define le16_to_cpu(val) bswap_16(val)
245 #define le32_to_cpu(val) bswap_32(val)
246 #endif
247 
248 static uint16_t elf16_to_cpu(uint16_t val)
249 {
250 	return le16_to_cpu(val);
251 }
252 
253 static uint32_t elf32_to_cpu(uint32_t val)
254 {
255 	return le32_to_cpu(val);
256 }
257 
258 static void read_ehdr(FILE *fp)
259 {
260 	if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
261 		die("Cannot read ELF header: %s\n",
262 			strerror(errno));
263 	}
264 	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
265 		die("No ELF magic\n");
266 	}
267 	if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
268 		die("Not a 32 bit executable\n");
269 	}
270 	if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
271 		die("Not a LSB ELF executable\n");
272 	}
273 	if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
274 		die("Unknown ELF version\n");
275 	}
276 	/* Convert the fields to native endian */
277 	ehdr.e_type      = elf16_to_cpu(ehdr.e_type);
278 	ehdr.e_machine   = elf16_to_cpu(ehdr.e_machine);
279 	ehdr.e_version   = elf32_to_cpu(ehdr.e_version);
280 	ehdr.e_entry     = elf32_to_cpu(ehdr.e_entry);
281 	ehdr.e_phoff     = elf32_to_cpu(ehdr.e_phoff);
282 	ehdr.e_shoff     = elf32_to_cpu(ehdr.e_shoff);
283 	ehdr.e_flags     = elf32_to_cpu(ehdr.e_flags);
284 	ehdr.e_ehsize    = elf16_to_cpu(ehdr.e_ehsize);
285 	ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
286 	ehdr.e_phnum     = elf16_to_cpu(ehdr.e_phnum);
287 	ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
288 	ehdr.e_shnum     = elf16_to_cpu(ehdr.e_shnum);
289 	ehdr.e_shstrndx  = elf16_to_cpu(ehdr.e_shstrndx);
290 
291 	if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
292 		die("Unsupported ELF header type\n");
293 	}
294 	if (ehdr.e_machine != EM_386) {
295 		die("Not for x86\n");
296 	}
297 	if (ehdr.e_version != EV_CURRENT) {
298 		die("Unknown ELF version\n");
299 	}
300 	if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
301 		die("Bad Elf header size\n");
302 	}
303 	if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
304 		die("Bad program header entry\n");
305 	}
306 	if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
307 		die("Bad section header entry\n");
308 	}
309 	if (ehdr.e_shstrndx >= ehdr.e_shnum) {
310 		die("String table index out of bounds\n");
311 	}
312 }
313 
314 static void read_shdrs(FILE *fp)
315 {
316 	int i;
317 	Elf32_Shdr shdr;
318 
319 	secs = calloc(ehdr.e_shnum, sizeof(struct section));
320 	if (!secs) {
321 		die("Unable to allocate %d section headers\n",
322 		    ehdr.e_shnum);
323 	}
324 	if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
325 		die("Seek to %d failed: %s\n",
326 			ehdr.e_shoff, strerror(errno));
327 	}
328 	for (i = 0; i < ehdr.e_shnum; i++) {
329 		struct section *sec = &secs[i];
330 		if (fread(&shdr, sizeof shdr, 1, fp) != 1)
331 			die("Cannot read ELF section headers %d/%d: %s\n",
332 			    i, ehdr.e_shnum, strerror(errno));
333 		sec->shdr.sh_name      = elf32_to_cpu(shdr.sh_name);
334 		sec->shdr.sh_type      = elf32_to_cpu(shdr.sh_type);
335 		sec->shdr.sh_flags     = elf32_to_cpu(shdr.sh_flags);
336 		sec->shdr.sh_addr      = elf32_to_cpu(shdr.sh_addr);
337 		sec->shdr.sh_offset    = elf32_to_cpu(shdr.sh_offset);
338 		sec->shdr.sh_size      = elf32_to_cpu(shdr.sh_size);
339 		sec->shdr.sh_link      = elf32_to_cpu(shdr.sh_link);
340 		sec->shdr.sh_info      = elf32_to_cpu(shdr.sh_info);
341 		sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign);
342 		sec->shdr.sh_entsize   = elf32_to_cpu(shdr.sh_entsize);
343 		if (sec->shdr.sh_link < ehdr.e_shnum)
344 			sec->link = &secs[sec->shdr.sh_link];
345 	}
346 
347 }
348 
349 static void read_strtabs(FILE *fp)
350 {
351 	int i;
352 	for (i = 0; i < ehdr.e_shnum; i++) {
353 		struct section *sec = &secs[i];
354 		if (sec->shdr.sh_type != SHT_STRTAB) {
355 			continue;
356 		}
357 		sec->strtab = malloc(sec->shdr.sh_size);
358 		if (!sec->strtab) {
359 			die("malloc of %d bytes for strtab failed\n",
360 				sec->shdr.sh_size);
361 		}
362 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
363 			die("Seek to %d failed: %s\n",
364 				sec->shdr.sh_offset, strerror(errno));
365 		}
366 		if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
367 		    != sec->shdr.sh_size) {
368 			die("Cannot read symbol table: %s\n",
369 				strerror(errno));
370 		}
371 	}
372 }
373 
374 static void read_symtabs(FILE *fp)
375 {
376 	int i,j;
377 	for (i = 0; i < ehdr.e_shnum; i++) {
378 		struct section *sec = &secs[i];
379 		if (sec->shdr.sh_type != SHT_SYMTAB) {
380 			continue;
381 		}
382 		sec->symtab = malloc(sec->shdr.sh_size);
383 		if (!sec->symtab) {
384 			die("malloc of %d bytes for symtab failed\n",
385 				sec->shdr.sh_size);
386 		}
387 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
388 			die("Seek to %d failed: %s\n",
389 				sec->shdr.sh_offset, strerror(errno));
390 		}
391 		if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
392 		    != sec->shdr.sh_size) {
393 			die("Cannot read symbol table: %s\n",
394 				strerror(errno));
395 		}
396 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
397 			Elf32_Sym *sym = &sec->symtab[j];
398 			sym->st_name  = elf32_to_cpu(sym->st_name);
399 			sym->st_value = elf32_to_cpu(sym->st_value);
400 			sym->st_size  = elf32_to_cpu(sym->st_size);
401 			sym->st_shndx = elf16_to_cpu(sym->st_shndx);
402 		}
403 	}
404 }
405 
406 
407 static void read_relocs(FILE *fp)
408 {
409 	int i,j;
410 	for (i = 0; i < ehdr.e_shnum; i++) {
411 		struct section *sec = &secs[i];
412 		if (sec->shdr.sh_type != SHT_REL) {
413 			continue;
414 		}
415 		sec->reltab = malloc(sec->shdr.sh_size);
416 		if (!sec->reltab) {
417 			die("malloc of %d bytes for relocs failed\n",
418 				sec->shdr.sh_size);
419 		}
420 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
421 			die("Seek to %d failed: %s\n",
422 				sec->shdr.sh_offset, strerror(errno));
423 		}
424 		if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
425 		    != sec->shdr.sh_size) {
426 			die("Cannot read symbol table: %s\n",
427 				strerror(errno));
428 		}
429 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
430 			Elf32_Rel *rel = &sec->reltab[j];
431 			rel->r_offset = elf32_to_cpu(rel->r_offset);
432 			rel->r_info   = elf32_to_cpu(rel->r_info);
433 		}
434 	}
435 }
436 
437 
438 static void print_absolute_symbols(void)
439 {
440 	int i;
441 	printf("Absolute symbols\n");
442 	printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
443 	for (i = 0; i < ehdr.e_shnum; i++) {
444 		struct section *sec = &secs[i];
445 		char *sym_strtab;
446 		int j;
447 
448 		if (sec->shdr.sh_type != SHT_SYMTAB) {
449 			continue;
450 		}
451 		sym_strtab = sec->link->strtab;
452 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
453 			Elf32_Sym *sym;
454 			const char *name;
455 			sym = &sec->symtab[j];
456 			name = sym_name(sym_strtab, sym);
457 			if (sym->st_shndx != SHN_ABS) {
458 				continue;
459 			}
460 			printf("%5d %08x %5d %10s %10s %12s %s\n",
461 				j, sym->st_value, sym->st_size,
462 				sym_type(ELF32_ST_TYPE(sym->st_info)),
463 				sym_bind(ELF32_ST_BIND(sym->st_info)),
464 				sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
465 				name);
466 		}
467 	}
468 	printf("\n");
469 }
470 
471 static void print_absolute_relocs(void)
472 {
473 	int i, printed = 0;
474 
475 	for (i = 0; i < ehdr.e_shnum; i++) {
476 		struct section *sec = &secs[i];
477 		struct section *sec_applies, *sec_symtab;
478 		char *sym_strtab;
479 		Elf32_Sym *sh_symtab;
480 		int j;
481 		if (sec->shdr.sh_type != SHT_REL) {
482 			continue;
483 		}
484 		sec_symtab  = sec->link;
485 		sec_applies = &secs[sec->shdr.sh_info];
486 		if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
487 			continue;
488 		}
489 		sh_symtab  = sec_symtab->symtab;
490 		sym_strtab = sec_symtab->link->strtab;
491 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
492 			Elf32_Rel *rel;
493 			Elf32_Sym *sym;
494 			const char *name;
495 			rel = &sec->reltab[j];
496 			sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
497 			name = sym_name(sym_strtab, sym);
498 			if (sym->st_shndx != SHN_ABS) {
499 				continue;
500 			}
501 
502 			/* Absolute symbols are not relocated if bzImage is
503 			 * loaded at a non-compiled address. Display a warning
504 			 * to user at compile time about the absolute
505 			 * relocations present.
506 			 *
507 			 * User need to audit the code to make sure
508 			 * some symbols which should have been section
509 			 * relative have not become absolute because of some
510 			 * linker optimization or wrong programming usage.
511 			 *
512 			 * Before warning check if this absolute symbol
513 			 * relocation is harmless.
514 			 */
515 			if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
516 				continue;
517 
518 			if (!printed) {
519 				printf("WARNING: Absolute relocations"
520 					" present\n");
521 				printf("Offset     Info     Type     Sym.Value "
522 					"Sym.Name\n");
523 				printed = 1;
524 			}
525 
526 			printf("%08x %08x %10s %08x  %s\n",
527 				rel->r_offset,
528 				rel->r_info,
529 				rel_type(ELF32_R_TYPE(rel->r_info)),
530 				sym->st_value,
531 				name);
532 		}
533 	}
534 
535 	if (printed)
536 		printf("\n");
537 }
538 
539 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
540 			int use_real_mode)
541 {
542 	int i;
543 	/* Walk through the relocations */
544 	for (i = 0; i < ehdr.e_shnum; i++) {
545 		char *sym_strtab;
546 		Elf32_Sym *sh_symtab;
547 		struct section *sec_applies, *sec_symtab;
548 		int j;
549 		struct section *sec = &secs[i];
550 
551 		if (sec->shdr.sh_type != SHT_REL) {
552 			continue;
553 		}
554 		sec_symtab  = sec->link;
555 		sec_applies = &secs[sec->shdr.sh_info];
556 		if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
557 			continue;
558 		}
559 		sh_symtab = sec_symtab->symtab;
560 		sym_strtab = sec_symtab->link->strtab;
561 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
562 			Elf32_Rel *rel;
563 			Elf32_Sym *sym;
564 			unsigned r_type;
565 			const char *symname;
566 			rel = &sec->reltab[j];
567 			sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
568 			r_type = ELF32_R_TYPE(rel->r_info);
569 
570 			switch (r_type) {
571 			case R_386_NONE:
572 			case R_386_PC32:
573 			case R_386_PC16:
574 			case R_386_PC8:
575 				/*
576 				 * NONE can be ignored and and PC relative
577 				 * relocations don't need to be adjusted.
578 				 */
579 				break;
580 
581 			case R_386_16:
582 				symname = sym_name(sym_strtab, sym);
583 				if (!use_real_mode)
584 					goto bad;
585 				if (sym->st_shndx == SHN_ABS) {
586 					if (is_reloc(S_ABS, symname))
587 						break;
588 					else if (!is_reloc(S_SEG, symname))
589 						goto bad;
590 				} else {
591 					if (is_reloc(S_LIN, symname))
592 						goto bad;
593 					else
594 						break;
595 				}
596 				visit(rel, sym);
597 				break;
598 
599 			case R_386_32:
600 				symname = sym_name(sym_strtab, sym);
601 				if (sym->st_shndx == SHN_ABS) {
602 					if (is_reloc(S_ABS, symname))
603 						break;
604 					else if (!is_reloc(S_REL, symname))
605 						goto bad;
606 				} else {
607 					if (use_real_mode &&
608 					    !is_reloc(S_LIN, symname))
609 						break;
610 				}
611 				visit(rel, sym);
612 				break;
613 			default:
614 				die("Unsupported relocation type: %s (%d)\n",
615 				    rel_type(r_type), r_type);
616 				break;
617 			bad:
618 				symname = sym_name(sym_strtab, sym);
619 				die("Invalid %s relocation: %s\n",
620 				    rel_type(r_type), symname);
621 			}
622 		}
623 	}
624 }
625 
626 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
627 {
628 	if (ELF32_R_TYPE(rel->r_info) == R_386_16)
629 		reloc16_count++;
630 	else
631 		reloc_count++;
632 }
633 
634 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
635 {
636 	/* Remember the address that needs to be adjusted. */
637 	if (ELF32_R_TYPE(rel->r_info) == R_386_16)
638 		relocs16[reloc16_idx++] = rel->r_offset;
639 	else
640 		relocs[reloc_idx++] = rel->r_offset;
641 }
642 
643 static int cmp_relocs(const void *va, const void *vb)
644 {
645 	const unsigned long *a, *b;
646 	a = va; b = vb;
647 	return (*a == *b)? 0 : (*a > *b)? 1 : -1;
648 }
649 
650 static int write32(unsigned int v, FILE *f)
651 {
652 	unsigned char buf[4];
653 
654 	put_unaligned_le32(v, buf);
655 	return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
656 }
657 
658 static void emit_relocs(int as_text, int use_real_mode)
659 {
660 	int i;
661 	/* Count how many relocations I have and allocate space for them. */
662 	reloc_count = 0;
663 	walk_relocs(count_reloc, use_real_mode);
664 	relocs = malloc(reloc_count * sizeof(relocs[0]));
665 	if (!relocs) {
666 		die("malloc of %d entries for relocs failed\n",
667 			reloc_count);
668 	}
669 
670 	relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
671 	if (!relocs16) {
672 		die("malloc of %d entries for relocs16 failed\n",
673 			reloc16_count);
674 	}
675 	/* Collect up the relocations */
676 	reloc_idx = 0;
677 	walk_relocs(collect_reloc, use_real_mode);
678 
679 	if (reloc16_count && !use_real_mode)
680 		die("Segment relocations found but --realmode not specified\n");
681 
682 	/* Order the relocations for more efficient processing */
683 	qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
684 	qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
685 
686 	/* Print the relocations */
687 	if (as_text) {
688 		/* Print the relocations in a form suitable that
689 		 * gas will like.
690 		 */
691 		printf(".section \".data.reloc\",\"a\"\n");
692 		printf(".balign 4\n");
693 		if (use_real_mode) {
694 			printf("\t.long %lu\n", reloc16_count);
695 			for (i = 0; i < reloc16_count; i++)
696 				printf("\t.long 0x%08lx\n", relocs16[i]);
697 			printf("\t.long %lu\n", reloc_count);
698 			for (i = 0; i < reloc_count; i++) {
699 				printf("\t.long 0x%08lx\n", relocs[i]);
700 			}
701 		} else {
702 			/* Print a stop */
703 			printf("\t.long 0x%08lx\n", (unsigned long)0);
704 			for (i = 0; i < reloc_count; i++) {
705 				printf("\t.long 0x%08lx\n", relocs[i]);
706 			}
707 		}
708 
709 		printf("\n");
710 	}
711 	else {
712 		if (use_real_mode) {
713 			write32(reloc16_count, stdout);
714 			for (i = 0; i < reloc16_count; i++)
715 				write32(relocs16[i], stdout);
716 			write32(reloc_count, stdout);
717 
718 			/* Now print each relocation */
719 			for (i = 0; i < reloc_count; i++)
720 				write32(relocs[i], stdout);
721 		} else {
722 			/* Print a stop */
723 			write32(0, stdout);
724 
725 			/* Now print each relocation */
726 			for (i = 0; i < reloc_count; i++) {
727 				write32(relocs[i], stdout);
728 			}
729 		}
730 	}
731 }
732 
733 static void usage(void)
734 {
735 	die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
736 }
737 
738 int main(int argc, char **argv)
739 {
740 	int show_absolute_syms, show_absolute_relocs;
741 	int as_text, use_real_mode;
742 	const char *fname;
743 	FILE *fp;
744 	int i;
745 
746 	show_absolute_syms = 0;
747 	show_absolute_relocs = 0;
748 	as_text = 0;
749 	use_real_mode = 0;
750 	fname = NULL;
751 	for (i = 1; i < argc; i++) {
752 		char *arg = argv[i];
753 		if (*arg == '-') {
754 			if (strcmp(arg, "--abs-syms") == 0) {
755 				show_absolute_syms = 1;
756 				continue;
757 			}
758 			if (strcmp(arg, "--abs-relocs") == 0) {
759 				show_absolute_relocs = 1;
760 				continue;
761 			}
762 			if (strcmp(arg, "--text") == 0) {
763 				as_text = 1;
764 				continue;
765 			}
766 			if (strcmp(arg, "--realmode") == 0) {
767 				use_real_mode = 1;
768 				continue;
769 			}
770 		}
771 		else if (!fname) {
772 			fname = arg;
773 			continue;
774 		}
775 		usage();
776 	}
777 	if (!fname) {
778 		usage();
779 	}
780 	regex_init(use_real_mode);
781 	fp = fopen(fname, "r");
782 	if (!fp) {
783 		die("Cannot open %s: %s\n",
784 			fname, strerror(errno));
785 	}
786 	read_ehdr(fp);
787 	read_shdrs(fp);
788 	read_strtabs(fp);
789 	read_symtabs(fp);
790 	read_relocs(fp);
791 	if (show_absolute_syms) {
792 		print_absolute_symbols();
793 		return 0;
794 	}
795 	if (show_absolute_relocs) {
796 		print_absolute_relocs();
797 		return 0;
798 	}
799 	emit_relocs(as_text, use_real_mode);
800 	return 0;
801 }
802