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
14static Elf_Ehdr ehdr;
15
16struct relocs {
17 uint32_t *offset;
18 unsigned long count;
19 unsigned long size;
20};
21
22static struct relocs relocs16;
23static struct relocs relocs32;
24#if ELF_BITS == 64
25static struct relocs relocs32neg;
26static struct relocs relocs64;
27#endif
28
29struct section {
30 Elf_Shdr shdr;
31 struct section *link;
32 Elf_Sym *symtab;
33 Elf_Rel *reltab;
34 char *strtab;
35};
36static struct section *secs;
37
38static 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 "__end_rodata_aligned|"
71 "__initramfs_start|"
72 "(jiffies|jiffies_64)|"
73#if ELF_BITS == 64
74 "__per_cpu_load|"
75 "init_per_cpu__.*|"
76 "__end_rodata_hpage_align|"
77#endif
78 "__vvar_page|"
79 "_end)$"
80};
81
82
83static const char * const sym_regex_realmode[S_NSYMTYPES] = {
84/*
85 * These symbols are known to be relative, even if the linker marks them
86 * as absolute (typically defined outside any section in the linker script.)
87 */
88 [S_REL] =
89 "^pa_",
90
91/*
92 * These are 16-bit segment symbols when compiling 16-bit code.
93 */
94 [S_SEG] =
95 "^real_mode_seg$",
96
97/*
98 * These are offsets belonging to segments, as opposed to linear addresses,
99 * when compiling 16-bit code.
100 */
101 [S_LIN] =
102 "^pa_",
103};
104
105static const char * const *sym_regex;
106
107static regex_t sym_regex_c[S_NSYMTYPES];
108static int is_reloc(enum symtype type, const char *sym_name)
109{
110 return sym_regex[type] &&
111 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
112}
113
114static void regex_init(int use_real_mode)
115{
116 char errbuf[128];
117 int err;
118 int i;
119
120 if (use_real_mode)
121 sym_regex = sym_regex_realmode;
122 else
123 sym_regex = sym_regex_kernel;
124
125 for (i = 0; i < S_NSYMTYPES; i++) {
126 if (!sym_regex[i])
127 continue;
128
129 err = regcomp(&sym_regex_c[i], sym_regex[i],
130 REG_EXTENDED|REG_NOSUB);
131
132 if (err) {
133 regerror(err, &sym_regex_c[i], errbuf, sizeof(errbuf));
134 die("%s", errbuf);
135 }
136 }
137}
138
139static const char *sym_type(unsigned type)
140{
141 static const char *type_name[] = {
142#define SYM_TYPE(X) [X] = #X
143 SYM_TYPE(STT_NOTYPE),
144 SYM_TYPE(STT_OBJECT),
145 SYM_TYPE(STT_FUNC),
146 SYM_TYPE(STT_SECTION),
147 SYM_TYPE(STT_FILE),
148 SYM_TYPE(STT_COMMON),
149 SYM_TYPE(STT_TLS),
150#undef SYM_TYPE
151 };
152 const char *name = "unknown sym type name";
153 if (type < ARRAY_SIZE(type_name)) {
154 name = type_name[type];
155 }
156 return name;
157}
158
159static const char *sym_bind(unsigned bind)
160{
161 static const char *bind_name[] = {
162#define SYM_BIND(X) [X] = #X
163 SYM_BIND(STB_LOCAL),
164 SYM_BIND(STB_GLOBAL),
165 SYM_BIND(STB_WEAK),
166#undef SYM_BIND
167 };
168 const char *name = "unknown sym bind name";
169 if (bind < ARRAY_SIZE(bind_name)) {
170 name = bind_name[bind];
171 }
172 return name;
173}
174
175static const char *sym_visibility(unsigned visibility)
176{
177 static const char *visibility_name[] = {
178#define SYM_VISIBILITY(X) [X] = #X
179 SYM_VISIBILITY(STV_DEFAULT),
180 SYM_VISIBILITY(STV_INTERNAL),
181 SYM_VISIBILITY(STV_HIDDEN),
182 SYM_VISIBILITY(STV_PROTECTED),
183#undef SYM_VISIBILITY
184 };
185 const char *name = "unknown sym visibility name";
186 if (visibility < ARRAY_SIZE(visibility_name)) {
187 name = visibility_name[visibility];
188 }
189 return name;
190}
191
192static const char *rel_type(unsigned type)
193{
194 static const char *type_name[] = {
195#define REL_TYPE(X) [X] = #X
196#if ELF_BITS == 64
197 REL_TYPE(R_X86_64_NONE),
198 REL_TYPE(R_X86_64_64),
199 REL_TYPE(R_X86_64_PC64),
200 REL_TYPE(R_X86_64_PC32),
201 REL_TYPE(R_X86_64_GOT32),
202 REL_TYPE(R_X86_64_PLT32),
203 REL_TYPE(R_X86_64_COPY),
204 REL_TYPE(R_X86_64_GLOB_DAT),
205 REL_TYPE(R_X86_64_JUMP_SLOT),
206 REL_TYPE(R_X86_64_RELATIVE),
207 REL_TYPE(R_X86_64_GOTPCREL),
208 REL_TYPE(R_X86_64_32),
209 REL_TYPE(R_X86_64_32S),
210 REL_TYPE(R_X86_64_16),
211 REL_TYPE(R_X86_64_PC16),
212 REL_TYPE(R_X86_64_8),
213 REL_TYPE(R_X86_64_PC8),
214#else
215 REL_TYPE(R_386_NONE),
216 REL_TYPE(R_386_32),
217 REL_TYPE(R_386_PC32),
218 REL_TYPE(R_386_GOT32),
219 REL_TYPE(R_386_PLT32),
220 REL_TYPE(R_386_COPY),
221 REL_TYPE(R_386_GLOB_DAT),
222 REL_TYPE(R_386_JMP_SLOT),
223 REL_TYPE(R_386_RELATIVE),
224 REL_TYPE(R_386_GOTOFF),
225 REL_TYPE(R_386_GOTPC),
226 REL_TYPE(R_386_8),
227 REL_TYPE(R_386_PC8),
228 REL_TYPE(R_386_16),
229 REL_TYPE(R_386_PC16),
230#endif
231#undef REL_TYPE
232 };
233 const char *name = "unknown type rel type name";
234 if (type < ARRAY_SIZE(type_name) && type_name[type]) {
235 name = type_name[type];
236 }
237 return name;
238}
239
240static const char *sec_name(unsigned shndx)
241{
242 const char *sec_strtab;
243 const char *name;
244 sec_strtab = secs[ehdr.e_shstrndx].strtab;
245 name = "<noname>";
246 if (shndx < ehdr.e_shnum) {
247 name = sec_strtab + secs[shndx].shdr.sh_name;
248 }
249 else if (shndx == SHN_ABS) {
250 name = "ABSOLUTE";
251 }
252 else if (shndx == SHN_COMMON) {
253 name = "COMMON";
254 }
255 return name;
256}
257
258static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
259{
260 const char *name;
261 name = "<noname>";
262 if (sym->st_name) {
263 name = sym_strtab + sym->st_name;
264 }
265 else {
266 name = sec_name(sym->st_shndx);
267 }
268 return name;
269}
270
271static Elf_Sym *sym_lookup(const char *symname)
272{
273 int i;
274 for (i = 0; i < ehdr.e_shnum; i++) {
275 struct section *sec = &secs[i];
276 long nsyms;
277 char *strtab;
278 Elf_Sym *symtab;
279 Elf_Sym *sym;
280
281 if (sec->shdr.sh_type != SHT_SYMTAB)
282 continue;
283
284 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
285 symtab = sec->symtab;
286 strtab = sec->link->strtab;
287
288 for (sym = symtab; --nsyms >= 0; sym++) {
289 if (!sym->st_name)
290 continue;
291 if (strcmp(symname, strtab + sym->st_name) == 0)
292 return sym;
293 }
294 }
295 return 0;
296}
297
298#if BYTE_ORDER == LITTLE_ENDIAN
299#define le16_to_cpu(val) (val)
300#define le32_to_cpu(val) (val)
301#define le64_to_cpu(val) (val)
302#endif
303#if BYTE_ORDER == BIG_ENDIAN
304#define le16_to_cpu(val) bswap_16(val)
305#define le32_to_cpu(val) bswap_32(val)
306#define le64_to_cpu(val) bswap_64(val)
307#endif
308
309static uint16_t elf16_to_cpu(uint16_t val)
310{
311 return le16_to_cpu(val);
312}
313
314static uint32_t elf32_to_cpu(uint32_t val)
315{
316 return le32_to_cpu(val);
317}
318
319#define elf_half_to_cpu(x) elf16_to_cpu(x)
320#define elf_word_to_cpu(x) elf32_to_cpu(x)
321
322#if ELF_BITS == 64
323static uint64_t elf64_to_cpu(uint64_t val)
324{
325 return le64_to_cpu(val);
326}
327#define elf_addr_to_cpu(x) elf64_to_cpu(x)
328#define elf_off_to_cpu(x) elf64_to_cpu(x)
329#define elf_xword_to_cpu(x) elf64_to_cpu(x)
330#else
331#define elf_addr_to_cpu(x) elf32_to_cpu(x)
332#define elf_off_to_cpu(x) elf32_to_cpu(x)
333#define elf_xword_to_cpu(x) elf32_to_cpu(x)
334#endif
335
336static void read_ehdr(FILE *fp)
337{
338 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
339 die("Cannot read ELF header: %s\n",
340 strerror(errno));
341 }
342 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
343 die("No ELF magic\n");
344 }
345 if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
346 die("Not a %d bit executable\n", ELF_BITS);
347 }
348 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
349 die("Not a LSB ELF executable\n");
350 }
351 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
352 die("Unknown ELF version\n");
353 }
354 /* Convert the fields to native endian */
355 ehdr.e_type = elf_half_to_cpu(ehdr.e_type);
356 ehdr.e_machine = elf_half_to_cpu(ehdr.e_machine);
357 ehdr.e_version = elf_word_to_cpu(ehdr.e_version);
358 ehdr.e_entry = elf_addr_to_cpu(ehdr.e_entry);
359 ehdr.e_phoff = elf_off_to_cpu(ehdr.e_phoff);
360 ehdr.e_shoff = elf_off_to_cpu(ehdr.e_shoff);
361 ehdr.e_flags = elf_word_to_cpu(ehdr.e_flags);
362 ehdr.e_ehsize = elf_half_to_cpu(ehdr.e_ehsize);
363 ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
364 ehdr.e_phnum = elf_half_to_cpu(ehdr.e_phnum);
365 ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
366 ehdr.e_shnum = elf_half_to_cpu(ehdr.e_shnum);
367 ehdr.e_shstrndx = elf_half_to_cpu(ehdr.e_shstrndx);
368
369 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
370 die("Unsupported ELF header type\n");
371 }
372 if (ehdr.e_machine != ELF_MACHINE) {
373 die("Not for %s\n", ELF_MACHINE_NAME);
374 }
375 if (ehdr.e_version != EV_CURRENT) {
376 die("Unknown ELF version\n");
377 }
378 if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {
379 die("Bad Elf header size\n");
380 }
381 if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {
382 die("Bad program header entry\n");
383 }
384 if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {
385 die("Bad section header entry\n");
386 }
387 if (ehdr.e_shstrndx >= ehdr.e_shnum) {
388 die("String table index out of bounds\n");
389 }
390}
391
392static void read_shdrs(FILE *fp)
393{
394 int i;
395 Elf_Shdr shdr;
396
397 secs = calloc(ehdr.e_shnum, sizeof(struct section));
398 if (!secs) {
399 die("Unable to allocate %d section headers\n",
400 ehdr.e_shnum);
401 }
402 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
403 die("Seek to %d failed: %s\n",
404 ehdr.e_shoff, strerror(errno));
405 }
406 for (i = 0; i < ehdr.e_shnum; i++) {
407 struct section *sec = &secs[i];
408 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
409 die("Cannot read ELF section headers %d/%d: %s\n",
410 i, ehdr.e_shnum, strerror(errno));
411 sec->shdr.sh_name = elf_word_to_cpu(shdr.sh_name);
412 sec->shdr.sh_type = elf_word_to_cpu(shdr.sh_type);
413 sec->shdr.sh_flags = elf_xword_to_cpu(shdr.sh_flags);
414 sec->shdr.sh_addr = elf_addr_to_cpu(shdr.sh_addr);
415 sec->shdr.sh_offset = elf_off_to_cpu(shdr.sh_offset);
416 sec->shdr.sh_size = elf_xword_to_cpu(shdr.sh_size);
417 sec->shdr.sh_link = elf_word_to_cpu(shdr.sh_link);
418 sec->shdr.sh_info = elf_word_to_cpu(shdr.sh_info);
419 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
420 sec->shdr.sh_entsize = elf_xword_to_cpu(shdr.sh_entsize);
421 if (sec->shdr.sh_link < ehdr.e_shnum)
422 sec->link = &secs[sec->shdr.sh_link];
423 }
424
425}
426
427static void read_strtabs(FILE *fp)
428{
429 int i;
430 for (i = 0; i < ehdr.e_shnum; i++) {
431 struct section *sec = &secs[i];
432 if (sec->shdr.sh_type != SHT_STRTAB) {
433 continue;
434 }
435 sec->strtab = malloc(sec->shdr.sh_size);
436 if (!sec->strtab) {
437 die("malloc of %d bytes for strtab failed\n",
438 sec->shdr.sh_size);
439 }
440 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
441 die("Seek to %d failed: %s\n",
442 sec->shdr.sh_offset, strerror(errno));
443 }
444 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
445 != sec->shdr.sh_size) {
446 die("Cannot read symbol table: %s\n",
447 strerror(errno));
448 }
449 }
450}
451
452static void read_symtabs(FILE *fp)
453{
454 int i,j;
455 for (i = 0; i < ehdr.e_shnum; i++) {
456 struct section *sec = &secs[i];
457 if (sec->shdr.sh_type != SHT_SYMTAB) {
458 continue;
459 }
460 sec->symtab = malloc(sec->shdr.sh_size);
461 if (!sec->symtab) {
462 die("malloc of %d bytes for symtab failed\n",
463 sec->shdr.sh_size);
464 }
465 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
466 die("Seek to %d failed: %s\n",
467 sec->shdr.sh_offset, strerror(errno));
468 }
469 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
470 != sec->shdr.sh_size) {
471 die("Cannot read symbol table: %s\n",
472 strerror(errno));
473 }
474 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
475 Elf_Sym *sym = &sec->symtab[j];
476 sym->st_name = elf_word_to_cpu(sym->st_name);
477 sym->st_value = elf_addr_to_cpu(sym->st_value);
478 sym->st_size = elf_xword_to_cpu(sym->st_size);
479 sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
480 }
481 }
482}
483
484
485static void read_relocs(FILE *fp)
486{
487 int i,j;
488 for (i = 0; i < ehdr.e_shnum; i++) {
489 struct section *sec = &secs[i];
490 if (sec->shdr.sh_type != SHT_REL_TYPE) {
491 continue;
492 }
493 sec->reltab = malloc(sec->shdr.sh_size);
494 if (!sec->reltab) {
495 die("malloc of %d bytes for relocs failed\n",
496 sec->shdr.sh_size);
497 }
498 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
499 die("Seek to %d failed: %s\n",
500 sec->shdr.sh_offset, strerror(errno));
501 }
502 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
503 != sec->shdr.sh_size) {
504 die("Cannot read symbol table: %s\n",
505 strerror(errno));
506 }
507 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
508 Elf_Rel *rel = &sec->reltab[j];
509 rel->r_offset = elf_addr_to_cpu(rel->r_offset);
510 rel->r_info = elf_xword_to_cpu(rel->r_info);
511#if (SHT_REL_TYPE == SHT_RELA)
512 rel->r_addend = elf_xword_to_cpu(rel->r_addend);
513#endif
514 }
515 }
516}
517
518
519static void print_absolute_symbols(void)
520{
521 int i;
522 const char *format;
523
524 if (ELF_BITS == 64)
525 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
526 else
527 format = "%5d %08"PRIx32" %5"PRId32" %10s %10s %12s %s\n";
528
529 printf("Absolute symbols\n");
530 printf(" Num: Value Size Type Bind Visibility Name\n");
531 for (i = 0; i < ehdr.e_shnum; i++) {
532 struct section *sec = &secs[i];
533 char *sym_strtab;
534 int j;
535
536 if (sec->shdr.sh_type != SHT_SYMTAB) {
537 continue;
538 }
539 sym_strtab = sec->link->strtab;
540 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
541 Elf_Sym *sym;
542 const char *name;
543 sym = &sec->symtab[j];
544 name = sym_name(sym_strtab, sym);
545 if (sym->st_shndx != SHN_ABS) {
546 continue;
547 }
548 printf(format,
549 j, sym->st_value, sym->st_size,
550 sym_type(ELF_ST_TYPE(sym->st_info)),
551 sym_bind(ELF_ST_BIND(sym->st_info)),
552 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
553 name);
554 }
555 }
556 printf("\n");
557}
558
559static void print_absolute_relocs(void)
560{
561 int i, printed = 0;
562 const char *format;
563
564 if (ELF_BITS == 64)
565 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64" %s\n";
566 else
567 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32" %s\n";
568
569 for (i = 0; i < ehdr.e_shnum; i++) {
570 struct section *sec = &secs[i];
571 struct section *sec_applies, *sec_symtab;
572 char *sym_strtab;
573 Elf_Sym *sh_symtab;
574 int j;
575 if (sec->shdr.sh_type != SHT_REL_TYPE) {
576 continue;
577 }
578 sec_symtab = sec->link;
579 sec_applies = &secs[sec->shdr.sh_info];
580 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
581 continue;
582 }
583 sh_symtab = sec_symtab->symtab;
584 sym_strtab = sec_symtab->link->strtab;
585 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
586 Elf_Rel *rel;
587 Elf_Sym *sym;
588 const char *name;
589 rel = &sec->reltab[j];
590 sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
591 name = sym_name(sym_strtab, sym);
592 if (sym->st_shndx != SHN_ABS) {
593 continue;
594 }
595
596 /* Absolute symbols are not relocated if bzImage is
597 * loaded at a non-compiled address. Display a warning
598 * to user at compile time about the absolute
599 * relocations present.
600 *
601 * User need to audit the code to make sure
602 * some symbols which should have been section
603 * relative have not become absolute because of some
604 * linker optimization or wrong programming usage.
605 *
606 * Before warning check if this absolute symbol
607 * relocation is harmless.
608 */
609 if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
610 continue;
611
612 if (!printed) {
613 printf("WARNING: Absolute relocations"
614 " present\n");
615 printf("Offset Info Type Sym.Value "
616 "Sym.Name\n");
617 printed = 1;
618 }
619
620 printf(format,
621 rel->r_offset,
622 rel->r_info,
623 rel_type(ELF_R_TYPE(rel->r_info)),
624 sym->st_value,
625 name);
626 }
627 }
628
629 if (printed)
630 printf("\n");
631}
632
633static void add_reloc(struct relocs *r, uint32_t offset)
634{
635 if (r->count == r->size) {
636 unsigned long newsize = r->size + 50000;
637 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
638
639 if (!mem)
640 die("realloc of %ld entries for relocs failed\n",
641 newsize);
642 r->offset = mem;
643 r->size = newsize;
644 }
645 r->offset[r->count++] = offset;
646}
647
648static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
649 Elf_Sym *sym, const char *symname))
650{
651 int i;
652 /* Walk through the relocations */
653 for (i = 0; i < ehdr.e_shnum; i++) {
654 char *sym_strtab;
655 Elf_Sym *sh_symtab;
656 struct section *sec_applies, *sec_symtab;
657 int j;
658 struct section *sec = &secs[i];
659
660 if (sec->shdr.sh_type != SHT_REL_TYPE) {
661 continue;
662 }
663 sec_symtab = sec->link;
664 sec_applies = &secs[sec->shdr.sh_info];
665 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
666 continue;
667 }
668 sh_symtab = sec_symtab->symtab;
669 sym_strtab = sec_symtab->link->strtab;
670 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
671 Elf_Rel *rel = &sec->reltab[j];
672 Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
673 const char *symname = sym_name(sym_strtab, sym);
674
675 process(sec, rel, sym, symname);
676 }
677 }
678}
679
680/*
681 * The .data..percpu section is a special case for x86_64 SMP kernels.
682 * It is used to initialize the actual per_cpu areas and to provide
683 * definitions for the per_cpu variables that correspond to their offsets
684 * within the percpu area. Since the values of all of the symbols need
685 * to be offsets from the start of the per_cpu area the virtual address
686 * (sh_addr) of .data..percpu is 0 in SMP kernels.
687 *
688 * This means that:
689 *
690 * Relocations that reference symbols in the per_cpu area do not
691 * need further relocation (since the value is an offset relative
692 * to the start of the per_cpu area that does not change).
693 *
694 * Relocations that apply to the per_cpu area need to have their
695 * offset adjusted by by the value of __per_cpu_load to make them
696 * point to the correct place in the loaded image (because the
697 * virtual address of .data..percpu is 0).
698 *
699 * For non SMP kernels .data..percpu is linked as part of the normal
700 * kernel data and does not require special treatment.
701 *
702 */
703static int per_cpu_shndx = -1;
704static Elf_Addr per_cpu_load_addr;
705
706static void percpu_init(void)
707{
708 int i;
709 for (i = 0; i < ehdr.e_shnum; i++) {
710 ElfW(Sym) *sym;
711 if (strcmp(sec_name(i), ".data..percpu"))
712 continue;
713
714 if (secs[i].shdr.sh_addr != 0) /* non SMP kernel */
715 return;
716
717 sym = sym_lookup("__per_cpu_load");
718 if (!sym)
719 die("can't find __per_cpu_load\n");
720
721 per_cpu_shndx = i;
722 per_cpu_load_addr = sym->st_value;
723 return;
724 }
725}
726
727#if ELF_BITS == 64
728
729/*
730 * Check to see if a symbol lies in the .data..percpu section.
731 *
732 * The linker incorrectly associates some symbols with the
733 * .data..percpu section so we also need to check the symbol
734 * name to make sure that we classify the symbol correctly.
735 *
736 * The GNU linker incorrectly associates:
737 * __init_begin
738 * __per_cpu_load
739 *
740 * The "gold" linker incorrectly associates:
741 * init_per_cpu__irq_stack_union
742 * init_per_cpu__gdt_page
743 */
744static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
745{
746 return (sym->st_shndx == per_cpu_shndx) &&
747 strcmp(symname, "__init_begin") &&
748 strcmp(symname, "__per_cpu_load") &&
749 strncmp(symname, "init_per_cpu_", 13);
750}
751
752
753static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
754 const char *symname)
755{
756 unsigned r_type = ELF64_R_TYPE(rel->r_info);
757 ElfW(Addr) offset = rel->r_offset;
758 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
759
760 if (sym->st_shndx == SHN_UNDEF)
761 return 0;
762
763 /*
764 * Adjust the offset if this reloc applies to the percpu section.
765 */
766 if (sec->shdr.sh_info == per_cpu_shndx)
767 offset += per_cpu_load_addr;
768
769 switch (r_type) {
770 case R_X86_64_NONE:
771 /* NONE can be ignored. */
772 break;
773
774 case R_X86_64_PC32:
775 case R_X86_64_PLT32:
776 /*
777 * PC relative relocations don't need to be adjusted unless
778 * referencing a percpu symbol.
779 *
780 * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
781 */
782 if (is_percpu_sym(sym, symname))
783 add_reloc(&relocs32neg, offset);
784 break;
785
786 case R_X86_64_PC64:
787 /*
788 * Only used by jump labels
789 */
790 if (is_percpu_sym(sym, symname))
791 die("Invalid R_X86_64_PC64 relocation against per-CPU symbol %s\n",
792 symname);
793 break;
794
795 case R_X86_64_32:
796 case R_X86_64_32S:
797 case R_X86_64_64:
798 /*
799 * References to the percpu area don't need to be adjusted.
800 */
801 if (is_percpu_sym(sym, symname))
802 break;
803
804 if (shn_abs) {
805 /*
806 * Whitelisted absolute symbols do not require
807 * relocation.
808 */
809 if (is_reloc(S_ABS, symname))
810 break;
811
812 die("Invalid absolute %s relocation: %s\n",
813 rel_type(r_type), symname);
814 break;
815 }
816
817 /*
818 * Relocation offsets for 64 bit kernels are output
819 * as 32 bits and sign extended back to 64 bits when
820 * the relocations are processed.
821 * Make sure that the offset will fit.
822 */
823 if ((int32_t)offset != (int64_t)offset)
824 die("Relocation offset doesn't fit in 32 bits\n");
825
826 if (r_type == R_X86_64_64)
827 add_reloc(&relocs64, offset);
828 else
829 add_reloc(&relocs32, offset);
830 break;
831
832 default:
833 die("Unsupported relocation type: %s (%d)\n",
834 rel_type(r_type), r_type);
835 break;
836 }
837
838 return 0;
839}
840
841#else
842
843static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
844 const char *symname)
845{
846 unsigned r_type = ELF32_R_TYPE(rel->r_info);
847 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
848
849 switch (r_type) {
850 case R_386_NONE:
851 case R_386_PC32:
852 case R_386_PC16:
853 case R_386_PC8:
854 /*
855 * NONE can be ignored and PC relative relocations don't
856 * need to be adjusted.
857 */
858 break;
859
860 case R_386_32:
861 if (shn_abs) {
862 /*
863 * Whitelisted absolute symbols do not require
864 * relocation.
865 */
866 if (is_reloc(S_ABS, symname))
867 break;
868
869 die("Invalid absolute %s relocation: %s\n",
870 rel_type(r_type), symname);
871 break;
872 }
873
874 add_reloc(&relocs32, rel->r_offset);
875 break;
876
877 default:
878 die("Unsupported relocation type: %s (%d)\n",
879 rel_type(r_type), r_type);
880 break;
881 }
882
883 return 0;
884}
885
886static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
887 const char *symname)
888{
889 unsigned r_type = ELF32_R_TYPE(rel->r_info);
890 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
891
892 switch (r_type) {
893 case R_386_NONE:
894 case R_386_PC32:
895 case R_386_PC16:
896 case R_386_PC8:
897 /*
898 * NONE can be ignored and PC relative relocations don't
899 * need to be adjusted.
900 */
901 break;
902
903 case R_386_16:
904 if (shn_abs) {
905 /*
906 * Whitelisted absolute symbols do not require
907 * relocation.
908 */
909 if (is_reloc(S_ABS, symname))
910 break;
911
912 if (is_reloc(S_SEG, symname)) {
913 add_reloc(&relocs16, rel->r_offset);
914 break;
915 }
916 } else {
917 if (!is_reloc(S_LIN, symname))
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 case R_386_32:
926 if (shn_abs) {
927 /*
928 * Whitelisted absolute symbols do not require
929 * relocation.
930 */
931 if (is_reloc(S_ABS, symname))
932 break;
933
934 if (is_reloc(S_REL, symname)) {
935 add_reloc(&relocs32, rel->r_offset);
936 break;
937 }
938 } else {
939 if (is_reloc(S_LIN, symname))
940 add_reloc(&relocs32, rel->r_offset);
941 break;
942 }
943 die("Invalid %s %s relocation: %s\n",
944 shn_abs ? "absolute" : "relative",
945 rel_type(r_type), symname);
946 break;
947
948 default:
949 die("Unsupported relocation type: %s (%d)\n",
950 rel_type(r_type), r_type);
951 break;
952 }
953
954 return 0;
955}
956
957#endif
958
959static int cmp_relocs(const void *va, const void *vb)
960{
961 const uint32_t *a, *b;
962 a = va; b = vb;
963 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
964}
965
966static void sort_relocs(struct relocs *r)
967{
968 qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
969}
970
971static int write32(uint32_t v, FILE *f)
972{
973 unsigned char buf[4];
974
975 put_unaligned_le32(v, buf);
976 return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
977}
978
979static int write32_as_text(uint32_t v, FILE *f)
980{
981 return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
982}
983
984static void emit_relocs(int as_text, int use_real_mode)
985{
986 int i;
987 int (*write_reloc)(uint32_t, FILE *) = write32;
988 int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
989 const char *symname);
990
991#if ELF_BITS == 64
992 if (!use_real_mode)
993 do_reloc = do_reloc64;
994 else
995 die("--realmode not valid for a 64-bit ELF file");
996#else
997 if (!use_real_mode)
998 do_reloc = do_reloc32;
999 else
1000 do_reloc = do_reloc_real;
1001#endif
1002
1003 /* Collect up the relocations */
1004 walk_relocs(do_reloc);
1005
1006 if (relocs16.count && !use_real_mode)
1007 die("Segment relocations found but --realmode not specified\n");
1008
1009 /* Order the relocations for more efficient processing */
1010 sort_relocs(&relocs32);
1011#if ELF_BITS == 64
1012 sort_relocs(&relocs32neg);
1013 sort_relocs(&relocs64);
1014#else
1015 sort_relocs(&relocs16);
1016#endif
1017
1018 /* Print the relocations */
1019 if (as_text) {
1020 /* Print the relocations in a form suitable that
1021 * gas will like.
1022 */
1023 printf(".section \".data.reloc\",\"a\"\n");
1024 printf(".balign 4\n");
1025 write_reloc = write32_as_text;
1026 }
1027
1028 if (use_real_mode) {
1029 write_reloc(relocs16.count, stdout);
1030 for (i = 0; i < relocs16.count; i++)
1031 write_reloc(relocs16.offset[i], stdout);
1032
1033 write_reloc(relocs32.count, stdout);
1034 for (i = 0; i < relocs32.count; i++)
1035 write_reloc(relocs32.offset[i], stdout);
1036 } else {
1037#if ELF_BITS == 64
1038 /* Print a stop */
1039 write_reloc(0, stdout);
1040
1041 /* Now print each relocation */
1042 for (i = 0; i < relocs64.count; i++)
1043 write_reloc(relocs64.offset[i], stdout);
1044
1045 /* Print a stop */
1046 write_reloc(0, stdout);
1047
1048 /* Now print each inverse 32-bit relocation */
1049 for (i = 0; i < relocs32neg.count; i++)
1050 write_reloc(relocs32neg.offset[i], stdout);
1051#endif
1052
1053 /* Print a stop */
1054 write_reloc(0, stdout);
1055
1056 /* Now print each relocation */
1057 for (i = 0; i < relocs32.count; i++)
1058 write_reloc(relocs32.offset[i], stdout);
1059 }
1060}
1061
1062/*
1063 * As an aid to debugging problems with different linkers
1064 * print summary information about the relocs.
1065 * Since different linkers tend to emit the sections in
1066 * different orders we use the section names in the output.
1067 */
1068static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1069 const char *symname)
1070{
1071 printf("%s\t%s\t%s\t%s\n",
1072 sec_name(sec->shdr.sh_info),
1073 rel_type(ELF_R_TYPE(rel->r_info)),
1074 symname,
1075 sec_name(sym->st_shndx));
1076 return 0;
1077}
1078
1079static void print_reloc_info(void)
1080{
1081 printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1082 walk_relocs(do_reloc_info);
1083}
1084
1085#if ELF_BITS == 64
1086# define process process_64
1087#else
1088# define process process_32
1089#endif
1090
1091void process(FILE *fp, int use_real_mode, int as_text,
1092 int show_absolute_syms, int show_absolute_relocs,
1093 int show_reloc_info)
1094{
1095 regex_init(use_real_mode);
1096 read_ehdr(fp);
1097 read_shdrs(fp);
1098 read_strtabs(fp);
1099 read_symtabs(fp);
1100 read_relocs(fp);
1101 if (ELF_BITS == 64)
1102 percpu_init();
1103 if (show_absolute_syms) {
1104 print_absolute_symbols();
1105 return;
1106 }
1107 if (show_absolute_relocs) {
1108 print_absolute_relocs();
1109 return;
1110 }
1111 if (show_reloc_info) {
1112 print_reloc_info();
1113 return;
1114 }
1115 emit_relocs(as_text, use_real_mode);
1116}
1117