xref: /openbmc/linux/arch/x86/tools/relocs.c (revision 6774def6)
1 /* This is included from relocs_32/64.c */
2 
3 #define ElfW(type)		_ElfW(ELF_BITS, type)
4 #define _ElfW(bits, type)	__ElfW(bits, type)
5 #define __ElfW(bits, type)	Elf##bits##_##type
6 
7 #define Elf_Addr		ElfW(Addr)
8 #define Elf_Ehdr		ElfW(Ehdr)
9 #define Elf_Phdr		ElfW(Phdr)
10 #define Elf_Shdr		ElfW(Shdr)
11 #define Elf_Sym			ElfW(Sym)
12 
13 static Elf_Ehdr ehdr;
14 
15 struct relocs {
16 	uint32_t	*offset;
17 	unsigned long	count;
18 	unsigned long	size;
19 };
20 
21 static struct relocs relocs16;
22 static struct relocs relocs32;
23 static struct relocs relocs64;
24 
25 struct section {
26 	Elf_Shdr       shdr;
27 	struct section *link;
28 	Elf_Sym        *symtab;
29 	Elf_Rel        *reltab;
30 	char           *strtab;
31 };
32 static struct section *secs;
33 
34 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
35 /*
36  * Following symbols have been audited. There values are constant and do
37  * not change if bzImage is loaded at a different physical address than
38  * the address for which it has been compiled. Don't warn user about
39  * absolute relocations present w.r.t these symbols.
40  */
41 	[S_ABS] =
42 	"^(xen_irq_disable_direct_reloc$|"
43 	"xen_save_fl_direct_reloc$|"
44 	"VDSO|"
45 	"__crc_)",
46 
47 /*
48  * These symbols are known to be relative, even if the linker marks them
49  * as absolute (typically defined outside any section in the linker script.)
50  */
51 	[S_REL] =
52 	"^(__init_(begin|end)|"
53 	"__x86_cpu_dev_(start|end)|"
54 	"(__parainstructions|__alt_instructions)(|_end)|"
55 	"(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
56 	"__(start|end)_pci_.*|"
57 	"__(start|end)_builtin_fw|"
58 	"__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
59 	"__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
60 	"__(start|stop)___param|"
61 	"__(start|stop)___modver|"
62 	"__(start|stop)___bug_table|"
63 	"__tracedata_(start|end)|"
64 	"__(start|stop)_notes|"
65 	"__end_rodata|"
66 	"__initramfs_start|"
67 	"(jiffies|jiffies_64)|"
68 #if ELF_BITS == 64
69 	"__per_cpu_load|"
70 	"init_per_cpu__.*|"
71 	"__end_rodata_hpage_align|"
72 #endif
73 	"__vvar_page|"
74 	"_end)$"
75 };
76 
77 
78 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
79 /*
80  * These symbols are known to be relative, even if the linker marks them
81  * as absolute (typically defined outside any section in the linker script.)
82  */
83 	[S_REL] =
84 	"^pa_",
85 
86 /*
87  * These are 16-bit segment symbols when compiling 16-bit code.
88  */
89 	[S_SEG] =
90 	"^real_mode_seg$",
91 
92 /*
93  * These are offsets belonging to segments, as opposed to linear addresses,
94  * when compiling 16-bit code.
95  */
96 	[S_LIN] =
97 	"^pa_",
98 };
99 
100 static const char * const *sym_regex;
101 
102 static regex_t sym_regex_c[S_NSYMTYPES];
103 static int is_reloc(enum symtype type, const char *sym_name)
104 {
105 	return sym_regex[type] &&
106 		!regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
107 }
108 
109 static void regex_init(int use_real_mode)
110 {
111         char errbuf[128];
112         int err;
113 	int i;
114 
115 	if (use_real_mode)
116 		sym_regex = sym_regex_realmode;
117 	else
118 		sym_regex = sym_regex_kernel;
119 
120 	for (i = 0; i < S_NSYMTYPES; i++) {
121 		if (!sym_regex[i])
122 			continue;
123 
124 		err = regcomp(&sym_regex_c[i], sym_regex[i],
125 			      REG_EXTENDED|REG_NOSUB);
126 
127 		if (err) {
128 			regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
129 			die("%s", errbuf);
130 		}
131         }
132 }
133 
134 static const char *sym_type(unsigned type)
135 {
136 	static const char *type_name[] = {
137 #define SYM_TYPE(X) [X] = #X
138 		SYM_TYPE(STT_NOTYPE),
139 		SYM_TYPE(STT_OBJECT),
140 		SYM_TYPE(STT_FUNC),
141 		SYM_TYPE(STT_SECTION),
142 		SYM_TYPE(STT_FILE),
143 		SYM_TYPE(STT_COMMON),
144 		SYM_TYPE(STT_TLS),
145 #undef SYM_TYPE
146 	};
147 	const char *name = "unknown sym type name";
148 	if (type < ARRAY_SIZE(type_name)) {
149 		name = type_name[type];
150 	}
151 	return name;
152 }
153 
154 static const char *sym_bind(unsigned bind)
155 {
156 	static const char *bind_name[] = {
157 #define SYM_BIND(X) [X] = #X
158 		SYM_BIND(STB_LOCAL),
159 		SYM_BIND(STB_GLOBAL),
160 		SYM_BIND(STB_WEAK),
161 #undef SYM_BIND
162 	};
163 	const char *name = "unknown sym bind name";
164 	if (bind < ARRAY_SIZE(bind_name)) {
165 		name = bind_name[bind];
166 	}
167 	return name;
168 }
169 
170 static const char *sym_visibility(unsigned visibility)
171 {
172 	static const char *visibility_name[] = {
173 #define SYM_VISIBILITY(X) [X] = #X
174 		SYM_VISIBILITY(STV_DEFAULT),
175 		SYM_VISIBILITY(STV_INTERNAL),
176 		SYM_VISIBILITY(STV_HIDDEN),
177 		SYM_VISIBILITY(STV_PROTECTED),
178 #undef SYM_VISIBILITY
179 	};
180 	const char *name = "unknown sym visibility name";
181 	if (visibility < ARRAY_SIZE(visibility_name)) {
182 		name = visibility_name[visibility];
183 	}
184 	return name;
185 }
186 
187 static const char *rel_type(unsigned type)
188 {
189 	static const char *type_name[] = {
190 #define REL_TYPE(X) [X] = #X
191 #if ELF_BITS == 64
192 		REL_TYPE(R_X86_64_NONE),
193 		REL_TYPE(R_X86_64_64),
194 		REL_TYPE(R_X86_64_PC32),
195 		REL_TYPE(R_X86_64_GOT32),
196 		REL_TYPE(R_X86_64_PLT32),
197 		REL_TYPE(R_X86_64_COPY),
198 		REL_TYPE(R_X86_64_GLOB_DAT),
199 		REL_TYPE(R_X86_64_JUMP_SLOT),
200 		REL_TYPE(R_X86_64_RELATIVE),
201 		REL_TYPE(R_X86_64_GOTPCREL),
202 		REL_TYPE(R_X86_64_32),
203 		REL_TYPE(R_X86_64_32S),
204 		REL_TYPE(R_X86_64_16),
205 		REL_TYPE(R_X86_64_PC16),
206 		REL_TYPE(R_X86_64_8),
207 		REL_TYPE(R_X86_64_PC8),
208 #else
209 		REL_TYPE(R_386_NONE),
210 		REL_TYPE(R_386_32),
211 		REL_TYPE(R_386_PC32),
212 		REL_TYPE(R_386_GOT32),
213 		REL_TYPE(R_386_PLT32),
214 		REL_TYPE(R_386_COPY),
215 		REL_TYPE(R_386_GLOB_DAT),
216 		REL_TYPE(R_386_JMP_SLOT),
217 		REL_TYPE(R_386_RELATIVE),
218 		REL_TYPE(R_386_GOTOFF),
219 		REL_TYPE(R_386_GOTPC),
220 		REL_TYPE(R_386_8),
221 		REL_TYPE(R_386_PC8),
222 		REL_TYPE(R_386_16),
223 		REL_TYPE(R_386_PC16),
224 #endif
225 #undef REL_TYPE
226 	};
227 	const char *name = "unknown type rel type name";
228 	if (type < ARRAY_SIZE(type_name) && type_name[type]) {
229 		name = type_name[type];
230 	}
231 	return name;
232 }
233 
234 static const char *sec_name(unsigned shndx)
235 {
236 	const char *sec_strtab;
237 	const char *name;
238 	sec_strtab = secs[ehdr.e_shstrndx].strtab;
239 	name = "<noname>";
240 	if (shndx < ehdr.e_shnum) {
241 		name = sec_strtab + secs[shndx].shdr.sh_name;
242 	}
243 	else if (shndx == SHN_ABS) {
244 		name = "ABSOLUTE";
245 	}
246 	else if (shndx == SHN_COMMON) {
247 		name = "COMMON";
248 	}
249 	return name;
250 }
251 
252 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
253 {
254 	const char *name;
255 	name = "<noname>";
256 	if (sym->st_name) {
257 		name = sym_strtab + sym->st_name;
258 	}
259 	else {
260 		name = sec_name(sym->st_shndx);
261 	}
262 	return name;
263 }
264 
265 static Elf_Sym *sym_lookup(const char *symname)
266 {
267 	int i;
268 	for (i = 0; i < ehdr.e_shnum; i++) {
269 		struct section *sec = &secs[i];
270 		long nsyms;
271 		char *strtab;
272 		Elf_Sym *symtab;
273 		Elf_Sym *sym;
274 
275 		if (sec->shdr.sh_type != SHT_SYMTAB)
276 			continue;
277 
278 		nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
279 		symtab = sec->symtab;
280 		strtab = sec->link->strtab;
281 
282 		for (sym = symtab; --nsyms >= 0; sym++) {
283 			if (!sym->st_name)
284 				continue;
285 			if (strcmp(symname, strtab + sym->st_name) == 0)
286 				return sym;
287 		}
288 	}
289 	return 0;
290 }
291 
292 #if BYTE_ORDER == LITTLE_ENDIAN
293 #define le16_to_cpu(val) (val)
294 #define le32_to_cpu(val) (val)
295 #define le64_to_cpu(val) (val)
296 #endif
297 #if BYTE_ORDER == BIG_ENDIAN
298 #define le16_to_cpu(val) bswap_16(val)
299 #define le32_to_cpu(val) bswap_32(val)
300 #define le64_to_cpu(val) bswap_64(val)
301 #endif
302 
303 static uint16_t elf16_to_cpu(uint16_t val)
304 {
305 	return le16_to_cpu(val);
306 }
307 
308 static uint32_t elf32_to_cpu(uint32_t val)
309 {
310 	return le32_to_cpu(val);
311 }
312 
313 #define elf_half_to_cpu(x)	elf16_to_cpu(x)
314 #define elf_word_to_cpu(x)	elf32_to_cpu(x)
315 
316 #if ELF_BITS == 64
317 static uint64_t elf64_to_cpu(uint64_t val)
318 {
319         return le64_to_cpu(val);
320 }
321 #define elf_addr_to_cpu(x)	elf64_to_cpu(x)
322 #define elf_off_to_cpu(x)	elf64_to_cpu(x)
323 #define elf_xword_to_cpu(x)	elf64_to_cpu(x)
324 #else
325 #define elf_addr_to_cpu(x)	elf32_to_cpu(x)
326 #define elf_off_to_cpu(x)	elf32_to_cpu(x)
327 #define elf_xword_to_cpu(x)	elf32_to_cpu(x)
328 #endif
329 
330 static void read_ehdr(FILE *fp)
331 {
332 	if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
333 		die("Cannot read ELF header: %s\n",
334 			strerror(errno));
335 	}
336 	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
337 		die("No ELF magic\n");
338 	}
339 	if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
340 		die("Not a %d bit executable\n", ELF_BITS);
341 	}
342 	if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
343 		die("Not a LSB ELF executable\n");
344 	}
345 	if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
346 		die("Unknown ELF version\n");
347 	}
348 	/* Convert the fields to native endian */
349 	ehdr.e_type      = elf_half_to_cpu(ehdr.e_type);
350 	ehdr.e_machine   = elf_half_to_cpu(ehdr.e_machine);
351 	ehdr.e_version   = elf_word_to_cpu(ehdr.e_version);
352 	ehdr.e_entry     = elf_addr_to_cpu(ehdr.e_entry);
353 	ehdr.e_phoff     = elf_off_to_cpu(ehdr.e_phoff);
354 	ehdr.e_shoff     = elf_off_to_cpu(ehdr.e_shoff);
355 	ehdr.e_flags     = elf_word_to_cpu(ehdr.e_flags);
356 	ehdr.e_ehsize    = elf_half_to_cpu(ehdr.e_ehsize);
357 	ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
358 	ehdr.e_phnum     = elf_half_to_cpu(ehdr.e_phnum);
359 	ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
360 	ehdr.e_shnum     = elf_half_to_cpu(ehdr.e_shnum);
361 	ehdr.e_shstrndx  = elf_half_to_cpu(ehdr.e_shstrndx);
362 
363 	if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
364 		die("Unsupported ELF header type\n");
365 	}
366 	if (ehdr.e_machine != ELF_MACHINE) {
367 		die("Not for %s\n", ELF_MACHINE_NAME);
368 	}
369 	if (ehdr.e_version != EV_CURRENT) {
370 		die("Unknown ELF version\n");
371 	}
372 	if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {
373 		die("Bad Elf header size\n");
374 	}
375 	if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {
376 		die("Bad program header entry\n");
377 	}
378 	if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {
379 		die("Bad section header entry\n");
380 	}
381 	if (ehdr.e_shstrndx >= ehdr.e_shnum) {
382 		die("String table index out of bounds\n");
383 	}
384 }
385 
386 static void read_shdrs(FILE *fp)
387 {
388 	int i;
389 	Elf_Shdr shdr;
390 
391 	secs = calloc(ehdr.e_shnum, sizeof(struct section));
392 	if (!secs) {
393 		die("Unable to allocate %d section headers\n",
394 		    ehdr.e_shnum);
395 	}
396 	if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
397 		die("Seek to %d failed: %s\n",
398 			ehdr.e_shoff, strerror(errno));
399 	}
400 	for (i = 0; i < ehdr.e_shnum; i++) {
401 		struct section *sec = &secs[i];
402 		if (fread(&shdr, sizeof shdr, 1, fp) != 1)
403 			die("Cannot read ELF section headers %d/%d: %s\n",
404 			    i, ehdr.e_shnum, strerror(errno));
405 		sec->shdr.sh_name      = elf_word_to_cpu(shdr.sh_name);
406 		sec->shdr.sh_type      = elf_word_to_cpu(shdr.sh_type);
407 		sec->shdr.sh_flags     = elf_xword_to_cpu(shdr.sh_flags);
408 		sec->shdr.sh_addr      = elf_addr_to_cpu(shdr.sh_addr);
409 		sec->shdr.sh_offset    = elf_off_to_cpu(shdr.sh_offset);
410 		sec->shdr.sh_size      = elf_xword_to_cpu(shdr.sh_size);
411 		sec->shdr.sh_link      = elf_word_to_cpu(shdr.sh_link);
412 		sec->shdr.sh_info      = elf_word_to_cpu(shdr.sh_info);
413 		sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
414 		sec->shdr.sh_entsize   = elf_xword_to_cpu(shdr.sh_entsize);
415 		if (sec->shdr.sh_link < ehdr.e_shnum)
416 			sec->link = &secs[sec->shdr.sh_link];
417 	}
418 
419 }
420 
421 static void read_strtabs(FILE *fp)
422 {
423 	int i;
424 	for (i = 0; i < ehdr.e_shnum; i++) {
425 		struct section *sec = &secs[i];
426 		if (sec->shdr.sh_type != SHT_STRTAB) {
427 			continue;
428 		}
429 		sec->strtab = malloc(sec->shdr.sh_size);
430 		if (!sec->strtab) {
431 			die("malloc of %d bytes for strtab failed\n",
432 				sec->shdr.sh_size);
433 		}
434 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
435 			die("Seek to %d failed: %s\n",
436 				sec->shdr.sh_offset, strerror(errno));
437 		}
438 		if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
439 		    != sec->shdr.sh_size) {
440 			die("Cannot read symbol table: %s\n",
441 				strerror(errno));
442 		}
443 	}
444 }
445 
446 static void read_symtabs(FILE *fp)
447 {
448 	int i,j;
449 	for (i = 0; i < ehdr.e_shnum; i++) {
450 		struct section *sec = &secs[i];
451 		if (sec->shdr.sh_type != SHT_SYMTAB) {
452 			continue;
453 		}
454 		sec->symtab = malloc(sec->shdr.sh_size);
455 		if (!sec->symtab) {
456 			die("malloc of %d bytes for symtab failed\n",
457 				sec->shdr.sh_size);
458 		}
459 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
460 			die("Seek to %d failed: %s\n",
461 				sec->shdr.sh_offset, strerror(errno));
462 		}
463 		if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
464 		    != sec->shdr.sh_size) {
465 			die("Cannot read symbol table: %s\n",
466 				strerror(errno));
467 		}
468 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
469 			Elf_Sym *sym = &sec->symtab[j];
470 			sym->st_name  = elf_word_to_cpu(sym->st_name);
471 			sym->st_value = elf_addr_to_cpu(sym->st_value);
472 			sym->st_size  = elf_xword_to_cpu(sym->st_size);
473 			sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
474 		}
475 	}
476 }
477 
478 
479 static void read_relocs(FILE *fp)
480 {
481 	int i,j;
482 	for (i = 0; i < ehdr.e_shnum; i++) {
483 		struct section *sec = &secs[i];
484 		if (sec->shdr.sh_type != SHT_REL_TYPE) {
485 			continue;
486 		}
487 		sec->reltab = malloc(sec->shdr.sh_size);
488 		if (!sec->reltab) {
489 			die("malloc of %d bytes for relocs failed\n",
490 				sec->shdr.sh_size);
491 		}
492 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
493 			die("Seek to %d failed: %s\n",
494 				sec->shdr.sh_offset, strerror(errno));
495 		}
496 		if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
497 		    != sec->shdr.sh_size) {
498 			die("Cannot read symbol table: %s\n",
499 				strerror(errno));
500 		}
501 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
502 			Elf_Rel *rel = &sec->reltab[j];
503 			rel->r_offset = elf_addr_to_cpu(rel->r_offset);
504 			rel->r_info   = elf_xword_to_cpu(rel->r_info);
505 #if (SHT_REL_TYPE == SHT_RELA)
506 			rel->r_addend = elf_xword_to_cpu(rel->r_addend);
507 #endif
508 		}
509 	}
510 }
511 
512 
513 static void print_absolute_symbols(void)
514 {
515 	int i;
516 	const char *format;
517 
518 	if (ELF_BITS == 64)
519 		format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
520 	else
521 		format = "%5d %08"PRIx32"  %5"PRId32" %10s %10s %12s %s\n";
522 
523 	printf("Absolute symbols\n");
524 	printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
525 	for (i = 0; i < ehdr.e_shnum; i++) {
526 		struct section *sec = &secs[i];
527 		char *sym_strtab;
528 		int j;
529 
530 		if (sec->shdr.sh_type != SHT_SYMTAB) {
531 			continue;
532 		}
533 		sym_strtab = sec->link->strtab;
534 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
535 			Elf_Sym *sym;
536 			const char *name;
537 			sym = &sec->symtab[j];
538 			name = sym_name(sym_strtab, sym);
539 			if (sym->st_shndx != SHN_ABS) {
540 				continue;
541 			}
542 			printf(format,
543 				j, sym->st_value, sym->st_size,
544 				sym_type(ELF_ST_TYPE(sym->st_info)),
545 				sym_bind(ELF_ST_BIND(sym->st_info)),
546 				sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
547 				name);
548 		}
549 	}
550 	printf("\n");
551 }
552 
553 static void print_absolute_relocs(void)
554 {
555 	int i, printed = 0;
556 	const char *format;
557 
558 	if (ELF_BITS == 64)
559 		format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64"  %s\n";
560 	else
561 		format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32"  %s\n";
562 
563 	for (i = 0; i < ehdr.e_shnum; i++) {
564 		struct section *sec = &secs[i];
565 		struct section *sec_applies, *sec_symtab;
566 		char *sym_strtab;
567 		Elf_Sym *sh_symtab;
568 		int j;
569 		if (sec->shdr.sh_type != SHT_REL_TYPE) {
570 			continue;
571 		}
572 		sec_symtab  = sec->link;
573 		sec_applies = &secs[sec->shdr.sh_info];
574 		if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
575 			continue;
576 		}
577 		sh_symtab  = sec_symtab->symtab;
578 		sym_strtab = sec_symtab->link->strtab;
579 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
580 			Elf_Rel *rel;
581 			Elf_Sym *sym;
582 			const char *name;
583 			rel = &sec->reltab[j];
584 			sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
585 			name = sym_name(sym_strtab, sym);
586 			if (sym->st_shndx != SHN_ABS) {
587 				continue;
588 			}
589 
590 			/* Absolute symbols are not relocated if bzImage is
591 			 * loaded at a non-compiled address. Display a warning
592 			 * to user at compile time about the absolute
593 			 * relocations present.
594 			 *
595 			 * User need to audit the code to make sure
596 			 * some symbols which should have been section
597 			 * relative have not become absolute because of some
598 			 * linker optimization or wrong programming usage.
599 			 *
600 			 * Before warning check if this absolute symbol
601 			 * relocation is harmless.
602 			 */
603 			if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
604 				continue;
605 
606 			if (!printed) {
607 				printf("WARNING: Absolute relocations"
608 					" present\n");
609 				printf("Offset     Info     Type     Sym.Value "
610 					"Sym.Name\n");
611 				printed = 1;
612 			}
613 
614 			printf(format,
615 				rel->r_offset,
616 				rel->r_info,
617 				rel_type(ELF_R_TYPE(rel->r_info)),
618 				sym->st_value,
619 				name);
620 		}
621 	}
622 
623 	if (printed)
624 		printf("\n");
625 }
626 
627 static void add_reloc(struct relocs *r, uint32_t offset)
628 {
629 	if (r->count == r->size) {
630 		unsigned long newsize = r->size + 50000;
631 		void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
632 
633 		if (!mem)
634 			die("realloc of %ld entries for relocs failed\n",
635                                 newsize);
636 		r->offset = mem;
637 		r->size = newsize;
638 	}
639 	r->offset[r->count++] = offset;
640 }
641 
642 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
643 			Elf_Sym *sym, const char *symname))
644 {
645 	int i;
646 	/* Walk through the relocations */
647 	for (i = 0; i < ehdr.e_shnum; i++) {
648 		char *sym_strtab;
649 		Elf_Sym *sh_symtab;
650 		struct section *sec_applies, *sec_symtab;
651 		int j;
652 		struct section *sec = &secs[i];
653 
654 		if (sec->shdr.sh_type != SHT_REL_TYPE) {
655 			continue;
656 		}
657 		sec_symtab  = sec->link;
658 		sec_applies = &secs[sec->shdr.sh_info];
659 		if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
660 			continue;
661 		}
662 		sh_symtab = sec_symtab->symtab;
663 		sym_strtab = sec_symtab->link->strtab;
664 		for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
665 			Elf_Rel *rel = &sec->reltab[j];
666 			Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
667 			const char *symname = sym_name(sym_strtab, sym);
668 
669 			process(sec, rel, sym, symname);
670 		}
671 	}
672 }
673 
674 /*
675  * The .data..percpu section is a special case for x86_64 SMP kernels.
676  * It is used to initialize the actual per_cpu areas and to provide
677  * definitions for the per_cpu variables that correspond to their offsets
678  * within the percpu area. Since the values of all of the symbols need
679  * to be offsets from the start of the per_cpu area the virtual address
680  * (sh_addr) of .data..percpu is 0 in SMP kernels.
681  *
682  * This means that:
683  *
684  *	Relocations that reference symbols in the per_cpu area do not
685  *	need further relocation (since the value is an offset relative
686  *	to the start of the per_cpu area that does not change).
687  *
688  *	Relocations that apply to the per_cpu area need to have their
689  *	offset adjusted by by the value of __per_cpu_load to make them
690  *	point to the correct place in the loaded image (because the
691  *	virtual address of .data..percpu is 0).
692  *
693  * For non SMP kernels .data..percpu is linked as part of the normal
694  * kernel data and does not require special treatment.
695  *
696  */
697 static int per_cpu_shndx	= -1;
698 static Elf_Addr per_cpu_load_addr;
699 
700 static void percpu_init(void)
701 {
702 	int i;
703 	for (i = 0; i < ehdr.e_shnum; i++) {
704 		ElfW(Sym) *sym;
705 		if (strcmp(sec_name(i), ".data..percpu"))
706 			continue;
707 
708 		if (secs[i].shdr.sh_addr != 0)	/* non SMP kernel */
709 			return;
710 
711 		sym = sym_lookup("__per_cpu_load");
712 		if (!sym)
713 			die("can't find __per_cpu_load\n");
714 
715 		per_cpu_shndx = i;
716 		per_cpu_load_addr = sym->st_value;
717 		return;
718 	}
719 }
720 
721 #if ELF_BITS == 64
722 
723 /*
724  * Check to see if a symbol lies in the .data..percpu section.
725  *
726  * The linker incorrectly associates some symbols with the
727  * .data..percpu section so we also need to check the symbol
728  * name to make sure that we classify the symbol correctly.
729  *
730  * The GNU linker incorrectly associates:
731  *	__init_begin
732  *	__per_cpu_load
733  *
734  * The "gold" linker incorrectly associates:
735  *	init_per_cpu__irq_stack_union
736  *	init_per_cpu__gdt_page
737  */
738 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
739 {
740 	return (sym->st_shndx == per_cpu_shndx) &&
741 		strcmp(symname, "__init_begin") &&
742 		strcmp(symname, "__per_cpu_load") &&
743 		strncmp(symname, "init_per_cpu_", 13);
744 }
745 
746 
747 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
748 		      const char *symname)
749 {
750 	unsigned r_type = ELF64_R_TYPE(rel->r_info);
751 	ElfW(Addr) offset = rel->r_offset;
752 	int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
753 
754 	if (sym->st_shndx == SHN_UNDEF)
755 		return 0;
756 
757 	/*
758 	 * Adjust the offset if this reloc applies to the percpu section.
759 	 */
760 	if (sec->shdr.sh_info == per_cpu_shndx)
761 		offset += per_cpu_load_addr;
762 
763 	switch (r_type) {
764 	case R_X86_64_NONE:
765 	case R_X86_64_PC32:
766 		/*
767 		 * NONE can be ignored and PC relative relocations don't
768 		 * need to be adjusted.
769 		 */
770 		break;
771 
772 	case R_X86_64_32:
773 	case R_X86_64_32S:
774 	case R_X86_64_64:
775 		/*
776 		 * References to the percpu area don't need to be adjusted.
777 		 */
778 		if (is_percpu_sym(sym, symname))
779 			break;
780 
781 		if (shn_abs) {
782 			/*
783 			 * Whitelisted absolute symbols do not require
784 			 * relocation.
785 			 */
786 			if (is_reloc(S_ABS, symname))
787 				break;
788 
789 			die("Invalid absolute %s relocation: %s\n",
790 			    rel_type(r_type), symname);
791 			break;
792 		}
793 
794 		/*
795 		 * Relocation offsets for 64 bit kernels are output
796 		 * as 32 bits and sign extended back to 64 bits when
797 		 * the relocations are processed.
798 		 * Make sure that the offset will fit.
799 		 */
800 		if ((int32_t)offset != (int64_t)offset)
801 			die("Relocation offset doesn't fit in 32 bits\n");
802 
803 		if (r_type == R_X86_64_64)
804 			add_reloc(&relocs64, offset);
805 		else
806 			add_reloc(&relocs32, offset);
807 		break;
808 
809 	default:
810 		die("Unsupported relocation type: %s (%d)\n",
811 		    rel_type(r_type), r_type);
812 		break;
813 	}
814 
815 	return 0;
816 }
817 
818 #else
819 
820 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
821 		      const char *symname)
822 {
823 	unsigned r_type = ELF32_R_TYPE(rel->r_info);
824 	int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
825 
826 	switch (r_type) {
827 	case R_386_NONE:
828 	case R_386_PC32:
829 	case R_386_PC16:
830 	case R_386_PC8:
831 		/*
832 		 * NONE can be ignored and PC relative relocations don't
833 		 * need to be adjusted.
834 		 */
835 		break;
836 
837 	case R_386_32:
838 		if (shn_abs) {
839 			/*
840 			 * Whitelisted absolute symbols do not require
841 			 * relocation.
842 			 */
843 			if (is_reloc(S_ABS, symname))
844 				break;
845 
846 			die("Invalid absolute %s relocation: %s\n",
847 			    rel_type(r_type), symname);
848 			break;
849 		}
850 
851 		add_reloc(&relocs32, rel->r_offset);
852 		break;
853 
854 	default:
855 		die("Unsupported relocation type: %s (%d)\n",
856 		    rel_type(r_type), r_type);
857 		break;
858 	}
859 
860 	return 0;
861 }
862 
863 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
864 			 const char *symname)
865 {
866 	unsigned r_type = ELF32_R_TYPE(rel->r_info);
867 	int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
868 
869 	switch (r_type) {
870 	case R_386_NONE:
871 	case R_386_PC32:
872 	case R_386_PC16:
873 	case R_386_PC8:
874 		/*
875 		 * NONE can be ignored and PC relative relocations don't
876 		 * need to be adjusted.
877 		 */
878 		break;
879 
880 	case R_386_16:
881 		if (shn_abs) {
882 			/*
883 			 * Whitelisted absolute symbols do not require
884 			 * relocation.
885 			 */
886 			if (is_reloc(S_ABS, symname))
887 				break;
888 
889 			if (is_reloc(S_SEG, symname)) {
890 				add_reloc(&relocs16, rel->r_offset);
891 				break;
892 			}
893 		} else {
894 			if (!is_reloc(S_LIN, symname))
895 				break;
896 		}
897 		die("Invalid %s %s relocation: %s\n",
898 		    shn_abs ? "absolute" : "relative",
899 		    rel_type(r_type), symname);
900 		break;
901 
902 	case R_386_32:
903 		if (shn_abs) {
904 			/*
905 			 * Whitelisted absolute symbols do not require
906 			 * relocation.
907 			 */
908 			if (is_reloc(S_ABS, symname))
909 				break;
910 
911 			if (is_reloc(S_REL, symname)) {
912 				add_reloc(&relocs32, rel->r_offset);
913 				break;
914 			}
915 		} else {
916 			if (is_reloc(S_LIN, symname))
917 				add_reloc(&relocs32, rel->r_offset);
918 			break;
919 		}
920 		die("Invalid %s %s relocation: %s\n",
921 		    shn_abs ? "absolute" : "relative",
922 		    rel_type(r_type), symname);
923 		break;
924 
925 	default:
926 		die("Unsupported relocation type: %s (%d)\n",
927 		    rel_type(r_type), r_type);
928 		break;
929 	}
930 
931 	return 0;
932 }
933 
934 #endif
935 
936 static int cmp_relocs(const void *va, const void *vb)
937 {
938 	const uint32_t *a, *b;
939 	a = va; b = vb;
940 	return (*a == *b)? 0 : (*a > *b)? 1 : -1;
941 }
942 
943 static void sort_relocs(struct relocs *r)
944 {
945 	qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
946 }
947 
948 static int write32(uint32_t v, FILE *f)
949 {
950 	unsigned char buf[4];
951 
952 	put_unaligned_le32(v, buf);
953 	return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
954 }
955 
956 static int write32_as_text(uint32_t v, FILE *f)
957 {
958 	return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
959 }
960 
961 static void emit_relocs(int as_text, int use_real_mode)
962 {
963 	int i;
964 	int (*write_reloc)(uint32_t, FILE *) = write32;
965 	int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
966 			const char *symname);
967 
968 #if ELF_BITS == 64
969 	if (!use_real_mode)
970 		do_reloc = do_reloc64;
971 	else
972 		die("--realmode not valid for a 64-bit ELF file");
973 #else
974 	if (!use_real_mode)
975 		do_reloc = do_reloc32;
976 	else
977 		do_reloc = do_reloc_real;
978 #endif
979 
980 	/* Collect up the relocations */
981 	walk_relocs(do_reloc);
982 
983 	if (relocs16.count && !use_real_mode)
984 		die("Segment relocations found but --realmode not specified\n");
985 
986 	/* Order the relocations for more efficient processing */
987 	sort_relocs(&relocs16);
988 	sort_relocs(&relocs32);
989 	sort_relocs(&relocs64);
990 
991 	/* Print the relocations */
992 	if (as_text) {
993 		/* Print the relocations in a form suitable that
994 		 * gas will like.
995 		 */
996 		printf(".section \".data.reloc\",\"a\"\n");
997 		printf(".balign 4\n");
998 		write_reloc = write32_as_text;
999 	}
1000 
1001 	if (use_real_mode) {
1002 		write_reloc(relocs16.count, stdout);
1003 		for (i = 0; i < relocs16.count; i++)
1004 			write_reloc(relocs16.offset[i], stdout);
1005 
1006 		write_reloc(relocs32.count, stdout);
1007 		for (i = 0; i < relocs32.count; i++)
1008 			write_reloc(relocs32.offset[i], stdout);
1009 	} else {
1010 		if (ELF_BITS == 64) {
1011 			/* Print a stop */
1012 			write_reloc(0, stdout);
1013 
1014 			/* Now print each relocation */
1015 			for (i = 0; i < relocs64.count; i++)
1016 				write_reloc(relocs64.offset[i], stdout);
1017 		}
1018 
1019 		/* Print a stop */
1020 		write_reloc(0, stdout);
1021 
1022 		/* Now print each relocation */
1023 		for (i = 0; i < relocs32.count; i++)
1024 			write_reloc(relocs32.offset[i], stdout);
1025 	}
1026 }
1027 
1028 /*
1029  * As an aid to debugging problems with different linkers
1030  * print summary information about the relocs.
1031  * Since different linkers tend to emit the sections in
1032  * different orders we use the section names in the output.
1033  */
1034 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1035 				const char *symname)
1036 {
1037 	printf("%s\t%s\t%s\t%s\n",
1038 		sec_name(sec->shdr.sh_info),
1039 		rel_type(ELF_R_TYPE(rel->r_info)),
1040 		symname,
1041 		sec_name(sym->st_shndx));
1042 	return 0;
1043 }
1044 
1045 static void print_reloc_info(void)
1046 {
1047 	printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1048 	walk_relocs(do_reloc_info);
1049 }
1050 
1051 #if ELF_BITS == 64
1052 # define process process_64
1053 #else
1054 # define process process_32
1055 #endif
1056 
1057 void process(FILE *fp, int use_real_mode, int as_text,
1058 	     int show_absolute_syms, int show_absolute_relocs,
1059 	     int show_reloc_info)
1060 {
1061 	regex_init(use_real_mode);
1062 	read_ehdr(fp);
1063 	read_shdrs(fp);
1064 	read_strtabs(fp);
1065 	read_symtabs(fp);
1066 	read_relocs(fp);
1067 	if (ELF_BITS == 64)
1068 		percpu_init();
1069 	if (show_absolute_syms) {
1070 		print_absolute_symbols();
1071 		return;
1072 	}
1073 	if (show_absolute_relocs) {
1074 		print_absolute_relocs();
1075 		return;
1076 	}
1077 	if (show_reloc_info) {
1078 		print_reloc_info();
1079 		return;
1080 	}
1081 	emit_relocs(as_text, use_real_mode);
1082 }
1083