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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
[cris-mirror.git] / arch / x86 / tools / relocs.c
blob220e97841e494c41e21b242a053b9ffcefeb2b4a
1 // SPDX-License-Identifier: GPL-2.0
2 /* This is included from relocs_32/64.c */
3
4 #define ElfW(type) _ElfW(ELF_BITS, type)
5 #define _ElfW(bits, type) __ElfW(bits, type)
6 #define __ElfW(bits, type) Elf##bits##_##type
7
8 #define Elf_Addr ElfW(Addr)
9 #define Elf_Ehdr ElfW(Ehdr)
10 #define Elf_Phdr ElfW(Phdr)
11 #define Elf_Shdr ElfW(Shdr)
12 #define Elf_Sym ElfW(Sym)
13
14 static Elf_Ehdr ehdr;
15
16 struct relocs {
17 uint32_t *offset;
18 unsigned long count;
19 unsigned long size;
20 };
21
22 static struct relocs relocs16;
23 static struct relocs relocs32;
24 #if ELF_BITS == 64
25 static struct relocs relocs32neg;
26 static struct relocs relocs64;
27 #endif
28
29 struct section {
30 Elf_Shdr shdr;
31 struct section *link;
32 Elf_Sym *symtab;
33 Elf_Rel *reltab;
34 char *strtab;
35 };
36 static struct section *secs;
37
38 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
39 /*
40 * Following symbols have been audited. There values are constant and do
41 * not change if bzImage is loaded at a different physical address than
42 * the address for which it has been compiled. Don't warn user about
43 * absolute relocations present w.r.t these symbols.
44 */
45 [S_ABS] =
46 "^(xen_irq_disable_direct_reloc$|"
47 "xen_save_fl_direct_reloc$|"
48 "VDSO|"
49 "__crc_)",
50
51 /*
52 * These symbols are known to be relative, even if the linker marks them
53 * as absolute (typically defined outside any section in the linker script.)
54 */
55 [S_REL] =
56 "^(__init_(begin|end)|"
57 "__x86_cpu_dev_(start|end)|"
58 "(__parainstructions|__alt_instructions)(|_end)|"
59 "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
60 "__(start|end)_pci_.*|"
61 "__(start|end)_builtin_fw|"
62 "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
63 "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
64 "__(start|stop)___param|"
65 "__(start|stop)___modver|"
66 "__(start|stop)___bug_table|"
67 "__tracedata_(start|end)|"
68 "__(start|stop)_notes|"
69 "__end_rodata|"
70 "__initramfs_start|"
71 "(jiffies|jiffies_64)|"
72 #if ELF_BITS == 64
73 "__per_cpu_load|"
74 "init_per_cpu__.*|"
75 "__end_rodata_hpage_align|"
76 #endif
77 "__vvar_page|"
78 "_end)$"
79 };
80
81
82 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
83 /*
84 * These symbols are known to be relative, even if the linker marks them
85 * as absolute (typically defined outside any section in the linker script.)
86 */
87 [S_REL] =
88 "^pa_",
89
90 /*
91 * These are 16-bit segment symbols when compiling 16-bit code.
92 */
93 [S_SEG] =
94 "^real_mode_seg$",
95
96 /*
97 * These are offsets belonging to segments, as opposed to linear addresses,
98 * when compiling 16-bit code.
99 */
100 [S_LIN] =
101 "^pa_",
102 };
103
104 static const char * const *sym_regex;
105
106 static regex_t sym_regex_c[S_NSYMTYPES];
107 static int is_reloc(enum symtype type, const char *sym_name)
108 {
109 return sym_regex[type] &&
110 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
111 }
112
113 static void regex_init(int use_real_mode)
114 {
115 char errbuf[128];
116 int err;
117 int i;
118
119 if (use_real_mode)
120 sym_regex = sym_regex_realmode;
121 else
122 sym_regex = sym_regex_kernel;
123
124 for (i = 0; i < S_NSYMTYPES; i++) {
125 if (!sym_regex[i])
126 continue;
127
128 err = regcomp(&sym_regex_c[i], sym_regex[i],
129 REG_EXTENDED|REG_NOSUB);
130
131 if (err) {
132 regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
133 die("%s", errbuf);
134 }
135 }
136 }
137
138 static const char *sym_type(unsigned type)
139 {
140 static const char *type_name[] = {
141 #define SYM_TYPE(X) [X] = #X
142 SYM_TYPE(STT_NOTYPE),
143 SYM_TYPE(STT_OBJECT),
144 SYM_TYPE(STT_FUNC),
145 SYM_TYPE(STT_SECTION),
146 SYM_TYPE(STT_FILE),
147 SYM_TYPE(STT_COMMON),
148 SYM_TYPE(STT_TLS),
149 #undef SYM_TYPE
150 };
151 const char *name = "unknown sym type name";
152 if (type < ARRAY_SIZE(type_name)) {
153 name = type_name[type];
154 }
155 return name;
156 }
157
158 static const char *sym_bind(unsigned bind)
159 {
160 static const char *bind_name[] = {
161 #define SYM_BIND(X) [X] = #X
162 SYM_BIND(STB_LOCAL),
163 SYM_BIND(STB_GLOBAL),
164 SYM_BIND(STB_WEAK),
165 #undef SYM_BIND
166 };
167 const char *name = "unknown sym bind name";
168 if (bind < ARRAY_SIZE(bind_name)) {
169 name = bind_name[bind];
170 }
171 return name;
172 }
173
174 static const char *sym_visibility(unsigned visibility)
175 {
176 static const char *visibility_name[] = {
177 #define SYM_VISIBILITY(X) [X] = #X
178 SYM_VISIBILITY(STV_DEFAULT),
179 SYM_VISIBILITY(STV_INTERNAL),
180 SYM_VISIBILITY(STV_HIDDEN),
181 SYM_VISIBILITY(STV_PROTECTED),
182 #undef SYM_VISIBILITY
183 };
184 const char *name = "unknown sym visibility name";
185 if (visibility < ARRAY_SIZE(visibility_name)) {
186 name = visibility_name[visibility];
187 }
188 return name;
189 }
190
191 static const char *rel_type(unsigned type)
192 {
193 static const char *type_name[] = {
194 #define REL_TYPE(X) [X] = #X
195 #if ELF_BITS == 64
196 REL_TYPE(R_X86_64_NONE),
197 REL_TYPE(R_X86_64_64),
198 REL_TYPE(R_X86_64_PC32),
199 REL_TYPE(R_X86_64_GOT32),
200 REL_TYPE(R_X86_64_PLT32),
201 REL_TYPE(R_X86_64_COPY),
202 REL_TYPE(R_X86_64_GLOB_DAT),
203 REL_TYPE(R_X86_64_JUMP_SLOT),
204 REL_TYPE(R_X86_64_RELATIVE),
205 REL_TYPE(R_X86_64_GOTPCREL),
206 REL_TYPE(R_X86_64_32),
207 REL_TYPE(R_X86_64_32S),
208 REL_TYPE(R_X86_64_16),
209 REL_TYPE(R_X86_64_PC16),
210 REL_TYPE(R_X86_64_8),
211 REL_TYPE(R_X86_64_PC8),
212 #else
213 REL_TYPE(R_386_NONE),
214 REL_TYPE(R_386_32),
215 REL_TYPE(R_386_PC32),
216 REL_TYPE(R_386_GOT32),
217 REL_TYPE(R_386_PLT32),
218 REL_TYPE(R_386_COPY),
219 REL_TYPE(R_386_GLOB_DAT),
220 REL_TYPE(R_386_JMP_SLOT),
221 REL_TYPE(R_386_RELATIVE),
222 REL_TYPE(R_386_GOTOFF),
223 REL_TYPE(R_386_GOTPC),
224 REL_TYPE(R_386_8),
225 REL_TYPE(R_386_PC8),
226 REL_TYPE(R_386_16),
227 REL_TYPE(R_386_PC16),
228 #endif
229 #undef REL_TYPE
230 };
231 const char *name = "unknown type rel type name";
232 if (type < ARRAY_SIZE(type_name) && type_name[type]) {
233 name = type_name[type];
234 }
235 return name;
236 }
237
238 static const char *sec_name(unsigned shndx)
239 {
240 const char *sec_strtab;
241 const char *name;
242 sec_strtab = secs[ehdr.e_shstrndx].strtab;
243 name = "<noname>";
244 if (shndx < ehdr.e_shnum) {
245 name = sec_strtab + secs[shndx].shdr.sh_name;
246 }
247 else if (shndx == SHN_ABS) {
248 name = "ABSOLUTE";
249 }
250 else if (shndx == SHN_COMMON) {
251 name = "COMMON";
252 }
253 return name;
254 }
255
256 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
257 {
258 const char *name;
259 name = "<noname>";
260 if (sym->st_name) {
261 name = sym_strtab + sym->st_name;
262 }
263 else {
264 name = sec_name(sym->st_shndx);
265 }
266 return name;
267 }
268
269 static Elf_Sym *sym_lookup(const char *symname)
270 {
271 int i;
272 for (i = 0; i < ehdr.e_shnum; i++) {
273 struct section *sec = &secs[i];
274 long nsyms;
275 char *strtab;
276 Elf_Sym *symtab;
277 Elf_Sym *sym;
278
279 if (sec->shdr.sh_type != SHT_SYMTAB)
280 continue;
281
282 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
283 symtab = sec->symtab;
284 strtab = sec->link->strtab;
285
286 for (sym = symtab; --nsyms >= 0; sym++) {
287 if (!sym->st_name)
288 continue;
289 if (strcmp(symname, strtab + sym->st_name) == 0)
290 return sym;
291 }
292 }
293 return 0;
294 }
295
296 #if BYTE_ORDER == LITTLE_ENDIAN
297 #define le16_to_cpu(val) (val)
298 #define le32_to_cpu(val) (val)
299 #define le64_to_cpu(val) (val)
300 #endif
301 #if BYTE_ORDER == BIG_ENDIAN
302 #define le16_to_cpu(val) bswap_16(val)
303 #define le32_to_cpu(val) bswap_32(val)
304 #define le64_to_cpu(val) bswap_64(val)
305 #endif
306
307 static uint16_t elf16_to_cpu(uint16_t val)
308 {
309 return le16_to_cpu(val);
310 }
311
312 static uint32_t elf32_to_cpu(uint32_t val)
313 {
314 return le32_to_cpu(val);
315 }
316
317 #define elf_half_to_cpu(x) elf16_to_cpu(x)
318 #define elf_word_to_cpu(x) elf32_to_cpu(x)
319
320 #if ELF_BITS == 64
321 static uint64_t elf64_to_cpu(uint64_t val)
322 {
323 return le64_to_cpu(val);
324 }
325 #define elf_addr_to_cpu(x) elf64_to_cpu(x)
326 #define elf_off_to_cpu(x) elf64_to_cpu(x)
327 #define elf_xword_to_cpu(x) elf64_to_cpu(x)
328 #else
329 #define elf_addr_to_cpu(x) elf32_to_cpu(x)
330 #define elf_off_to_cpu(x) elf32_to_cpu(x)
331 #define elf_xword_to_cpu(x) elf32_to_cpu(x)
332 #endif
333
334 static void read_ehdr(FILE *fp)
335 {
336 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
337 die("Cannot read ELF header: %s\n",
338 strerror(errno));
339 }
340 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
341 die("No ELF magic\n");
342 }
343 if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
344 die("Not a %d bit executable\n", ELF_BITS);
345 }
346 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
347 die("Not a LSB ELF executable\n");
348 }
349 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
350 die("Unknown ELF version\n");
351 }
352 /* Convert the fields to native endian */
353 ehdr.e_type = elf_half_to_cpu(ehdr.e_type);
354 ehdr.e_machine = elf_half_to_cpu(ehdr.e_machine);
355 ehdr.e_version = elf_word_to_cpu(ehdr.e_version);
356 ehdr.e_entry = elf_addr_to_cpu(ehdr.e_entry);
357 ehdr.e_phoff = elf_off_to_cpu(ehdr.e_phoff);
358 ehdr.e_shoff = elf_off_to_cpu(ehdr.e_shoff);
359 ehdr.e_flags = elf_word_to_cpu(ehdr.e_flags);
360 ehdr.e_ehsize = elf_half_to_cpu(ehdr.e_ehsize);
361 ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
362 ehdr.e_phnum = elf_half_to_cpu(ehdr.e_phnum);
363 ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
364 ehdr.e_shnum = elf_half_to_cpu(ehdr.e_shnum);
365 ehdr.e_shstrndx = elf_half_to_cpu(ehdr.e_shstrndx);
366
367 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
368 die("Unsupported ELF header type\n");
369 }
370 if (ehdr.e_machine != ELF_MACHINE) {
371 die("Not for %s\n", ELF_MACHINE_NAME);
372 }
373 if (ehdr.e_version != EV_CURRENT) {
374 die("Unknown ELF version\n");
375 }
376 if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {
377 die("Bad Elf header size\n");
378 }
379 if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {
380 die("Bad program header entry\n");
381 }
382 if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {
383 die("Bad section header entry\n");
384 }
385 if (ehdr.e_shstrndx >= ehdr.e_shnum) {
386 die("String table index out of bounds\n");
387 }
388 }
389
390 static void read_shdrs(FILE *fp)
391 {
392 int i;
393 Elf_Shdr shdr;
394
395 secs = calloc(ehdr.e_shnum, sizeof(struct section));
396 if (!secs) {
397 die("Unable to allocate %d section headers\n",
398 ehdr.e_shnum);
399 }
400 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
401 die("Seek to %d failed: %s\n",
402 ehdr.e_shoff, strerror(errno));
403 }
404 for (i = 0; i < ehdr.e_shnum; i++) {
405 struct section *sec = &secs[i];
406 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
407 die("Cannot read ELF section headers %d/%d: %s\n",
408 i, ehdr.e_shnum, strerror(errno));
409 sec->shdr.sh_name = elf_word_to_cpu(shdr.sh_name);
410 sec->shdr.sh_type = elf_word_to_cpu(shdr.sh_type);
411 sec->shdr.sh_flags = elf_xword_to_cpu(shdr.sh_flags);
412 sec->shdr.sh_addr = elf_addr_to_cpu(shdr.sh_addr);
413 sec->shdr.sh_offset = elf_off_to_cpu(shdr.sh_offset);
414 sec->shdr.sh_size = elf_xword_to_cpu(shdr.sh_size);
415 sec->shdr.sh_link = elf_word_to_cpu(shdr.sh_link);
416 sec->shdr.sh_info = elf_word_to_cpu(shdr.sh_info);
417 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
418 sec->shdr.sh_entsize = elf_xword_to_cpu(shdr.sh_entsize);
419 if (sec->shdr.sh_link < ehdr.e_shnum)
420 sec->link = &secs[sec->shdr.sh_link];
421 }
422
423 }
424
425 static void read_strtabs(FILE *fp)
426 {
427 int i;
428 for (i = 0; i < ehdr.e_shnum; i++) {
429 struct section *sec = &secs[i];
430 if (sec->shdr.sh_type != SHT_STRTAB) {
431 continue;
432 }
433 sec->strtab = malloc(sec->shdr.sh_size);
434 if (!sec->strtab) {
435 die("malloc of %d bytes for strtab failed\n",
436 sec->shdr.sh_size);
437 }
438 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
439 die("Seek to %d failed: %s\n",
440 sec->shdr.sh_offset, strerror(errno));
441 }
442 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
443 != sec->shdr.sh_size) {
444 die("Cannot read symbol table: %s\n",
445 strerror(errno));
446 }
447 }
448 }
449
450 static void read_symtabs(FILE *fp)
451 {
452 int i,j;
453 for (i = 0; i < ehdr.e_shnum; i++) {
454 struct section *sec = &secs[i];
455 if (sec->shdr.sh_type != SHT_SYMTAB) {
456 continue;
457 }
458 sec->symtab = malloc(sec->shdr.sh_size);
459 if (!sec->symtab) {
460 die("malloc of %d bytes for symtab failed\n",
461 sec->shdr.sh_size);
462 }
463 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
464 die("Seek to %d failed: %s\n",
465 sec->shdr.sh_offset, strerror(errno));
466 }
467 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
468 != sec->shdr.sh_size) {
469 die("Cannot read symbol table: %s\n",
470 strerror(errno));
471 }
472 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
473 Elf_Sym *sym = &sec->symtab[j];
474 sym->st_name = elf_word_to_cpu(sym->st_name);
475 sym->st_value = elf_addr_to_cpu(sym->st_value);
476 sym->st_size = elf_xword_to_cpu(sym->st_size);
477 sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
478 }
479 }
480 }
481
482
483 static void read_relocs(FILE *fp)
484 {
485 int i,j;
486 for (i = 0; i < ehdr.e_shnum; i++) {
487 struct section *sec = &secs[i];
488 if (sec->shdr.sh_type != SHT_REL_TYPE) {
489 continue;
490 }
491 sec->reltab = malloc(sec->shdr.sh_size);
492 if (!sec->reltab) {
493 die("malloc of %d bytes for relocs failed\n",
494 sec->shdr.sh_size);
495 }
496 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
497 die("Seek to %d failed: %s\n",
498 sec->shdr.sh_offset, strerror(errno));
499 }
500 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
501 != sec->shdr.sh_size) {
502 die("Cannot read symbol table: %s\n",
503 strerror(errno));
504 }
505 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
506 Elf_Rel *rel = &sec->reltab[j];
507 rel->r_offset = elf_addr_to_cpu(rel->r_offset);
508 rel->r_info = elf_xword_to_cpu(rel->r_info);
509 #if (SHT_REL_TYPE == SHT_RELA)
510 rel->r_addend = elf_xword_to_cpu(rel->r_addend);
511 #endif
512 }
513 }
514 }
515
516
517 static void print_absolute_symbols(void)
518 {
519 int i;
520 const char *format;
521
522 if (ELF_BITS == 64)
523 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
524 else
525 format = "%5d %08"PRIx32" %5"PRId32" %10s %10s %12s %s\n";
526
527 printf("Absolute symbols\n");
528 printf(" Num: Value Size Type Bind Visibility Name\n");
529 for (i = 0; i < ehdr.e_shnum; i++) {
530 struct section *sec = &secs[i];
531 char *sym_strtab;
532 int j;
533
534 if (sec->shdr.sh_type != SHT_SYMTAB) {
535 continue;
536 }
537 sym_strtab = sec->link->strtab;
538 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
539 Elf_Sym *sym;
540 const char *name;
541 sym = &sec->symtab[j];
542 name = sym_name(sym_strtab, sym);
543 if (sym->st_shndx != SHN_ABS) {
544 continue;
545 }
546 printf(format,
547 j, sym->st_value, sym->st_size,
548 sym_type(ELF_ST_TYPE(sym->st_info)),
549 sym_bind(ELF_ST_BIND(sym->st_info)),
550 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
551 name);
552 }
553 }
554 printf("\n");
555 }
556
557 static void print_absolute_relocs(void)
558 {
559 int i, printed = 0;
560 const char *format;
561
562 if (ELF_BITS == 64)
563 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64" %s\n";
564 else
565 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32" %s\n";
566
567 for (i = 0; i < ehdr.e_shnum; i++) {
568 struct section *sec = &secs[i];
569 struct section *sec_applies, *sec_symtab;
570 char *sym_strtab;
571 Elf_Sym *sh_symtab;
572 int j;
573 if (sec->shdr.sh_type != SHT_REL_TYPE) {
574 continue;
575 }
576 sec_symtab = sec->link;
577 sec_applies = &secs[sec->shdr.sh_info];
578 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
579 continue;
580 }
581 sh_symtab = sec_symtab->symtab;
582 sym_strtab = sec_symtab->link->strtab;
583 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
584 Elf_Rel *rel;
585 Elf_Sym *sym;
586 const char *name;
587 rel = &sec->reltab[j];
588 sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
589 name = sym_name(sym_strtab, sym);
590 if (sym->st_shndx != SHN_ABS) {
591 continue;
592 }
593
594 /* Absolute symbols are not relocated if bzImage is
595 * loaded at a non-compiled address. Display a warning
596 * to user at compile time about the absolute
597 * relocations present.
598 *
599 * User need to audit the code to make sure
600 * some symbols which should have been section
601 * relative have not become absolute because of some
602 * linker optimization or wrong programming usage.
603 *
604 * Before warning check if this absolute symbol
605 * relocation is harmless.
606 */
607 if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
608 continue;
609
610 if (!printed) {
611 printf("WARNING: Absolute relocations"
612 " present\n");
613 printf("Offset Info Type Sym.Value "
614 "Sym.Name\n");
615 printed = 1;
616 }
617
618 printf(format,
619 rel->r_offset,
620 rel->r_info,
621 rel_type(ELF_R_TYPE(rel->r_info)),
622 sym->st_value,
623 name);
624 }
625 }
626
627 if (printed)
628 printf("\n");
629 }
630
631 static void add_reloc(struct relocs *r, uint32_t offset)
632 {
633 if (r->count == r->size) {
634 unsigned long newsize = r->size + 50000;
635 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
636
637 if (!mem)
638 die("realloc of %ld entries for relocs failed\n",
639 newsize);
640 r->offset = mem;
641 r->size = newsize;
642 }
643 r->offset[r->count++] = offset;
644 }
645
646 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
647 Elf_Sym *sym, const char *symname))
648 {
649 int i;
650 /* Walk through the relocations */
651 for (i = 0; i < ehdr.e_shnum; i++) {
652 char *sym_strtab;
653 Elf_Sym *sh_symtab;
654 struct section *sec_applies, *sec_symtab;
655 int j;
656 struct section *sec = &secs[i];
657
658 if (sec->shdr.sh_type != SHT_REL_TYPE) {
659 continue;
660 }
661 sec_symtab = sec->link;
662 sec_applies = &secs[sec->shdr.sh_info];
663 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
664 continue;
665 }
666 sh_symtab = sec_symtab->symtab;
667 sym_strtab = sec_symtab->link->strtab;
668 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
669 Elf_Rel *rel = &sec->reltab[j];
670 Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
671 const char *symname = sym_name(sym_strtab, sym);
672
673 process(sec, rel, sym, symname);
674 }
675 }
676 }
677
678 /*
679 * The .data..percpu section is a special case for x86_64 SMP kernels.
680 * It is used to initialize the actual per_cpu areas and to provide
681 * definitions for the per_cpu variables that correspond to their offsets
682 * within the percpu area. Since the values of all of the symbols need
683 * to be offsets from the start of the per_cpu area the virtual address
684 * (sh_addr) of .data..percpu is 0 in SMP kernels.
685 *
686 * This means that:
687 *
688 * Relocations that reference symbols in the per_cpu area do not
689 * need further relocation (since the value is an offset relative
690 * to the start of the per_cpu area that does not change).
691 *
692 * Relocations that apply to the per_cpu area need to have their
693 * offset adjusted by by the value of __per_cpu_load to make them
694 * point to the correct place in the loaded image (because the
695 * virtual address of .data..percpu is 0).
696 *
697 * For non SMP kernels .data..percpu is linked as part of the normal
698 * kernel data and does not require special treatment.
699 *
700 */
701 static int per_cpu_shndx = -1;
702 static Elf_Addr per_cpu_load_addr;
703
704 static void percpu_init(void)
705 {
706 int i;
707 for (i = 0; i < ehdr.e_shnum; i++) {
708 ElfW(Sym) *sym;
709 if (strcmp(sec_name(i), ".data..percpu"))
710 continue;
711
712 if (secs[i].shdr.sh_addr != 0) /* non SMP kernel */
713 return;
714
715 sym = sym_lookup("__per_cpu_load");
716 if (!sym)
717 die("can't find __per_cpu_load\n");
718
719 per_cpu_shndx = i;
720 per_cpu_load_addr = sym->st_value;
721 return;
722 }
723 }
724
725 #if ELF_BITS == 64
726
727 /*
728 * Check to see if a symbol lies in the .data..percpu section.
729 *
730 * The linker incorrectly associates some symbols with the
731 * .data..percpu section so we also need to check the symbol
732 * name to make sure that we classify the symbol correctly.
733 *
734 * The GNU linker incorrectly associates:
735 * __init_begin
736 * __per_cpu_load
737 *
738 * The "gold" linker incorrectly associates:
739 * init_per_cpu__irq_stack_union
740 * init_per_cpu__gdt_page
741 */
742 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
743 {
744 return (sym->st_shndx == per_cpu_shndx) &&
745 strcmp(symname, "__init_begin") &&
746 strcmp(symname, "__per_cpu_load") &&
747 strncmp(symname, "init_per_cpu_", 13);
748 }
749
750
751 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
752 const char *symname)
753 {
754 unsigned r_type = ELF64_R_TYPE(rel->r_info);
755 ElfW(Addr) offset = rel->r_offset;
756 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
757
758 if (sym->st_shndx == SHN_UNDEF)
759 return 0;
760
761 /*
762 * Adjust the offset if this reloc applies to the percpu section.
763 */
764 if (sec->shdr.sh_info == per_cpu_shndx)
765 offset += per_cpu_load_addr;
766
767 switch (r_type) {
768 case R_X86_64_NONE:
769 /* NONE can be ignored. */
770 break;
771
772 case R_X86_64_PC32:
773 case R_X86_64_PLT32:
774 /*
775 * PC relative relocations don't need to be adjusted unless
776 * referencing a percpu symbol.
777 *
778 * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
779 */
780 if (is_percpu_sym(sym, symname))
781 add_reloc(&relocs32neg, offset);
782 break;
783
784 case R_X86_64_32:
785 case R_X86_64_32S:
786 case R_X86_64_64:
787 /*
788 * References to the percpu area don't need to be adjusted.
789 */
790 if (is_percpu_sym(sym, symname))
791 break;
792
793 if (shn_abs) {
794 /*
795 * Whitelisted absolute symbols do not require
796 * relocation.
797 */
798 if (is_reloc(S_ABS, symname))
799 break;
800
801 die("Invalid absolute %s relocation: %s\n",
802 rel_type(r_type), symname);
803 break;
804 }
805
806 /*
807 * Relocation offsets for 64 bit kernels are output
808 * as 32 bits and sign extended back to 64 bits when
809 * the relocations are processed.
810 * Make sure that the offset will fit.
811 */
812 if ((int32_t)offset != (int64_t)offset)
813 die("Relocation offset doesn't fit in 32 bits\n");
814
815 if (r_type == R_X86_64_64)
816 add_reloc(&relocs64, offset);
817 else
818 add_reloc(&relocs32, offset);
819 break;
820
821 default:
822 die("Unsupported relocation type: %s (%d)\n",
823 rel_type(r_type), r_type);
824 break;
825 }
826
827 return 0;
828 }
829
830 #else
831
832 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
833 const char *symname)
834 {
835 unsigned r_type = ELF32_R_TYPE(rel->r_info);
836 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
837
838 switch (r_type) {
839 case R_386_NONE:
840 case R_386_PC32:
841 case R_386_PC16:
842 case R_386_PC8:
843 /*
844 * NONE can be ignored and PC relative relocations don't
845 * need to be adjusted.
846 */
847 break;
848
849 case R_386_32:
850 if (shn_abs) {
851 /*
852 * Whitelisted absolute symbols do not require
853 * relocation.
854 */
855 if (is_reloc(S_ABS, symname))
856 break;
857
858 die("Invalid absolute %s relocation: %s\n",
859 rel_type(r_type), symname);
860 break;
861 }
862
863 add_reloc(&relocs32, rel->r_offset);
864 break;
865
866 default:
867 die("Unsupported relocation type: %s (%d)\n",
868 rel_type(r_type), r_type);
869 break;
870 }
871
872 return 0;
873 }
874
875 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
876 const char *symname)
877 {
878 unsigned r_type = ELF32_R_TYPE(rel->r_info);
879 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
880
881 switch (r_type) {
882 case R_386_NONE:
883 case R_386_PC32:
884 case R_386_PC16:
885 case R_386_PC8:
886 /*
887 * NONE can be ignored and PC relative relocations don't
888 * need to be adjusted.
889 */
890 break;
891
892 case R_386_16:
893 if (shn_abs) {
894 /*
895 * Whitelisted absolute symbols do not require
896 * relocation.
897 */
898 if (is_reloc(S_ABS, symname))
899 break;
900
901 if (is_reloc(S_SEG, symname)) {
902 add_reloc(&relocs16, rel->r_offset);
903 break;
904 }
905 } else {
906 if (!is_reloc(S_LIN, symname))
907 break;
908 }
909 die("Invalid %s %s relocation: %s\n",
910 shn_abs ? "absolute" : "relative",
911 rel_type(r_type), symname);
912 break;
913
914 case R_386_32:
915 if (shn_abs) {
916 /*
917 * Whitelisted absolute symbols do not require
918 * relocation.
919 */
920 if (is_reloc(S_ABS, symname))
921 break;
922
923 if (is_reloc(S_REL, symname)) {
924 add_reloc(&relocs32, rel->r_offset);
925 break;
926 }
927 } else {
928 if (is_reloc(S_LIN, symname))
929 add_reloc(&relocs32, rel->r_offset);
930 break;
931 }
932 die("Invalid %s %s relocation: %s\n",
933 shn_abs ? "absolute" : "relative",
934 rel_type(r_type), symname);
935 break;
936
937 default:
938 die("Unsupported relocation type: %s (%d)\n",
939 rel_type(r_type), r_type);
940 break;
941 }
942
943 return 0;
944 }
945
946 #endif
947
948 static int cmp_relocs(const void *va, const void *vb)
949 {
950 const uint32_t *a, *b;
951 a = va; b = vb;
952 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
953 }
954
955 static void sort_relocs(struct relocs *r)
956 {
957 qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
958 }
959
960 static int write32(uint32_t v, FILE *f)
961 {
962 unsigned char buf[4];
963
964 put_unaligned_le32(v, buf);
965 return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
966 }
967
968 static int write32_as_text(uint32_t v, FILE *f)
969 {
970 return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
971 }
972
973 static void emit_relocs(int as_text, int use_real_mode)
974 {
975 int i;
976 int (*write_reloc)(uint32_t, FILE *) = write32;
977 int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
978 const char *symname);
979
980 #if ELF_BITS == 64
981 if (!use_real_mode)
982 do_reloc = do_reloc64;
983 else
984 die("--realmode not valid for a 64-bit ELF file");
985 #else
986 if (!use_real_mode)
987 do_reloc = do_reloc32;
988 else
989 do_reloc = do_reloc_real;
990 #endif
991
992 /* Collect up the relocations */
993 walk_relocs(do_reloc);
994
995 if (relocs16.count && !use_real_mode)
996 die("Segment relocations found but --realmode not specified\n");
997
998 /* Order the relocations for more efficient processing */
999 sort_relocs(&relocs32);
1000 #if ELF_BITS == 64
1001 sort_relocs(&relocs32neg);
1002 sort_relocs(&relocs64);
1003 #else
1004 sort_relocs(&relocs16);
1005 #endif
1006
1007 /* Print the relocations */
1008 if (as_text) {
1009 /* Print the relocations in a form suitable that
1010 * gas will like.
1011 */
1012 printf(".section \".data.reloc\",\"a\"\n");
1013 printf(".balign 4\n");
1014 write_reloc = write32_as_text;
1015 }
1016
1017 if (use_real_mode) {
1018 write_reloc(relocs16.count, stdout);
1019 for (i = 0; i < relocs16.count; i++)
1020 write_reloc(relocs16.offset[i], stdout);
1021
1022 write_reloc(relocs32.count, stdout);
1023 for (i = 0; i < relocs32.count; i++)
1024 write_reloc(relocs32.offset[i], stdout);
1025 } else {
1026 #if ELF_BITS == 64
1027 /* Print a stop */
1028 write_reloc(0, stdout);
1029
1030 /* Now print each relocation */
1031 for (i = 0; i < relocs64.count; i++)
1032 write_reloc(relocs64.offset[i], stdout);
1033
1034 /* Print a stop */
1035 write_reloc(0, stdout);
1036
1037 /* Now print each inverse 32-bit relocation */
1038 for (i = 0; i < relocs32neg.count; i++)
1039 write_reloc(relocs32neg.offset[i], stdout);
1040 #endif
1041
1042 /* Print a stop */
1043 write_reloc(0, stdout);
1044
1045 /* Now print each relocation */
1046 for (i = 0; i < relocs32.count; i++)
1047 write_reloc(relocs32.offset[i], stdout);
1048 }
1049 }
1050
1051 /*
1052 * As an aid to debugging problems with different linkers
1053 * print summary information about the relocs.
1054 * Since different linkers tend to emit the sections in
1055 * different orders we use the section names in the output.
1056 */
1057 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1058 const char *symname)
1059 {
1060 printf("%s\t%s\t%s\t%s\n",
1061 sec_name(sec->shdr.sh_info),
1062 rel_type(ELF_R_TYPE(rel->r_info)),
1063 symname,
1064 sec_name(sym->st_shndx));
1065 return 0;
1066 }
1067
1068 static void print_reloc_info(void)
1069 {
1070 printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1071 walk_relocs(do_reloc_info);
1072 }
1073
1074 #if ELF_BITS == 64
1075 # define process process_64
1076 #else
1077 # define process process_32
1078 #endif
1079
1080 void process(FILE *fp, int use_real_mode, int as_text,
1081 int show_absolute_syms, int show_absolute_relocs,
1082 int show_reloc_info)
1083 {
1084 regex_init(use_real_mode);
1085 read_ehdr(fp);
1086 read_shdrs(fp);
1087 read_strtabs(fp);
1088 read_symtabs(fp);
1089 read_relocs(fp);
1090 if (ELF_BITS == 64)
1091 percpu_init();
1092 if (show_absolute_syms) {
1093 print_absolute_symbols();
1094 return;
1095 }
1096 if (show_absolute_relocs) {
1097 print_absolute_relocs();
1098 return;
1099 }
1100 if (show_reloc_info) {
1101 print_reloc_info();
1102 return;
1103 }
1104 emit_relocs(as_text, use_real_mode);
1105 }
CRIS linux kernel tree