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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;
15static unsigned long shnum;
16static unsigned int shstrndx;
17
18struct relocs {
19 uint32_t *offset;
20 unsigned long count;
21 unsigned long size;
22};
23
24static struct relocs relocs16;
25static struct relocs relocs32;
26#if ELF_BITS == 64
27static struct relocs relocs32neg;
28static struct relocs relocs64;
29#endif
30
31struct section {
32 Elf_Shdr shdr;
33 struct section *link;
34 Elf_Sym *symtab;
35 Elf_Rel *reltab;
36 char *strtab;
37};
38static struct section *secs;
39
40static const char * const sym_regex_kernel[S_NSYMTYPES] = {
41/*
42 * Following symbols have been audited. There values are constant and do
43 * not change if bzImage is loaded at a different physical address than
44 * the address for which it has been compiled. Don't warn user about
45 * absolute relocations present w.r.t these symbols.
46 */
47 [S_ABS] =
48 "^(xen_irq_disable_direct_reloc$|"
49 "xen_save_fl_direct_reloc$|"
50 "VDSO|"
51 "__crc_)",
52
53/*
54 * These symbols are known to be relative, even if the linker marks them
55 * as absolute (typically defined outside any section in the linker script.)
56 */
57 [S_REL] =
58 "^(__init_(begin|end)|"
59 "__x86_cpu_dev_(start|end)|"
60 "(__parainstructions|__alt_instructions)(|_end)|"
61 "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
62 "__(start|end)_pci_.*|"
63 "__(start|end)_builtin_fw|"
64 "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
65 "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
66 "__(start|stop)___param|"
67 "__(start|stop)___modver|"
68 "__(start|stop)___bug_table|"
69 "__tracedata_(start|end)|"
70 "__(start|stop)_notes|"
71 "__end_rodata|"
72 "__end_rodata_aligned|"
73 "__initramfs_start|"
74 "(jiffies|jiffies_64)|"
75#if ELF_BITS == 64
76 "__per_cpu_load|"
77 "init_per_cpu__.*|"
78 "__end_rodata_hpage_align|"
79#endif
80 "__vvar_page|"
81 "_end)$"
82};
83
84
85static const char * const sym_regex_realmode[S_NSYMTYPES] = {
86/*
87 * These symbols are known to be relative, even if the linker marks them
88 * as absolute (typically defined outside any section in the linker script.)
89 */
90 [S_REL] =
91 "^pa_",
92
93/*
94 * These are 16-bit segment symbols when compiling 16-bit code.
95 */
96 [S_SEG] =
97 "^real_mode_seg$",
98
99/*
100 * These are offsets belonging to segments, as opposed to linear addresses,
101 * when compiling 16-bit code.
102 */
103 [S_LIN] =
104 "^pa_",
105};
106
107static const char * const *sym_regex;
108
109static regex_t sym_regex_c[S_NSYMTYPES];
110static int is_reloc(enum symtype type, const char *sym_name)
111{
112 return sym_regex[type] &&
113 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
114}
115
116static void regex_init(int use_real_mode)
117{
118 char errbuf[128];
119 int err;
120 int i;
121
122 if (use_real_mode)
123 sym_regex = sym_regex_realmode;
124 else
125 sym_regex = sym_regex_kernel;
126
127 for (i = 0; i < S_NSYMTYPES; i++) {
128 if (!sym_regex[i])
129 continue;
130
131 err = regcomp(&sym_regex_c[i], sym_regex[i],
132 REG_EXTENDED|REG_NOSUB);
133
134 if (err) {
135 regerror(err, &sym_regex_c[i], errbuf, sizeof(errbuf));
136 die("%s", errbuf);
137 }
138 }
139}
140
141static const char *sym_type(unsigned type)
142{
143 static const char *type_name[] = {
144#define SYM_TYPE(X) [X] = #X
145 SYM_TYPE(STT_NOTYPE),
146 SYM_TYPE(STT_OBJECT),
147 SYM_TYPE(STT_FUNC),
148 SYM_TYPE(STT_SECTION),
149 SYM_TYPE(STT_FILE),
150 SYM_TYPE(STT_COMMON),
151 SYM_TYPE(STT_TLS),
152#undef SYM_TYPE
153 };
154 const char *name = "unknown sym type name";
155 if (type < ARRAY_SIZE(type_name)) {
156 name = type_name[type];
157 }
158 return name;
159}
160
161static const char *sym_bind(unsigned bind)
162{
163 static const char *bind_name[] = {
164#define SYM_BIND(X) [X] = #X
165 SYM_BIND(STB_LOCAL),
166 SYM_BIND(STB_GLOBAL),
167 SYM_BIND(STB_WEAK),
168#undef SYM_BIND
169 };
170 const char *name = "unknown sym bind name";
171 if (bind < ARRAY_SIZE(bind_name)) {
172 name = bind_name[bind];
173 }
174 return name;
175}
176
177static const char *sym_visibility(unsigned visibility)
178{
179 static const char *visibility_name[] = {
180#define SYM_VISIBILITY(X) [X] = #X
181 SYM_VISIBILITY(STV_DEFAULT),
182 SYM_VISIBILITY(STV_INTERNAL),
183 SYM_VISIBILITY(STV_HIDDEN),
184 SYM_VISIBILITY(STV_PROTECTED),
185#undef SYM_VISIBILITY
186 };
187 const char *name = "unknown sym visibility name";
188 if (visibility < ARRAY_SIZE(visibility_name)) {
189 name = visibility_name[visibility];
190 }
191 return name;
192}
193
194static const char *rel_type(unsigned type)
195{
196 static const char *type_name[] = {
197#define REL_TYPE(X) [X] = #X
198#if ELF_BITS == 64
199 REL_TYPE(R_X86_64_NONE),
200 REL_TYPE(R_X86_64_64),
201 REL_TYPE(R_X86_64_PC64),
202 REL_TYPE(R_X86_64_PC32),
203 REL_TYPE(R_X86_64_GOT32),
204 REL_TYPE(R_X86_64_PLT32),
205 REL_TYPE(R_X86_64_COPY),
206 REL_TYPE(R_X86_64_GLOB_DAT),
207 REL_TYPE(R_X86_64_JUMP_SLOT),
208 REL_TYPE(R_X86_64_RELATIVE),
209 REL_TYPE(R_X86_64_GOTPCREL),
210 REL_TYPE(R_X86_64_32),
211 REL_TYPE(R_X86_64_32S),
212 REL_TYPE(R_X86_64_16),
213 REL_TYPE(R_X86_64_PC16),
214 REL_TYPE(R_X86_64_8),
215 REL_TYPE(R_X86_64_PC8),
216#else
217 REL_TYPE(R_386_NONE),
218 REL_TYPE(R_386_32),
219 REL_TYPE(R_386_PC32),
220 REL_TYPE(R_386_GOT32),
221 REL_TYPE(R_386_PLT32),
222 REL_TYPE(R_386_COPY),
223 REL_TYPE(R_386_GLOB_DAT),
224 REL_TYPE(R_386_JMP_SLOT),
225 REL_TYPE(R_386_RELATIVE),
226 REL_TYPE(R_386_GOTOFF),
227 REL_TYPE(R_386_GOTPC),
228 REL_TYPE(R_386_8),
229 REL_TYPE(R_386_PC8),
230 REL_TYPE(R_386_16),
231 REL_TYPE(R_386_PC16),
232#endif
233#undef REL_TYPE
234 };
235 const char *name = "unknown type rel type name";
236 if (type < ARRAY_SIZE(type_name) && type_name[type]) {
237 name = type_name[type];
238 }
239 return name;
240}
241
242static const char *sec_name(unsigned shndx)
243{
244 const char *sec_strtab;
245 const char *name;
246 sec_strtab = secs[shstrndx].strtab;
247 name = "<noname>";
248 if (shndx < shnum) {
249 name = sec_strtab + secs[shndx].shdr.sh_name;
250 }
251 else if (shndx == SHN_ABS) {
252 name = "ABSOLUTE";
253 }
254 else if (shndx == SHN_COMMON) {
255 name = "COMMON";
256 }
257 return name;
258}
259
260static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
261{
262 const char *name;
263 name = "<noname>";
264 if (sym->st_name) {
265 name = sym_strtab + sym->st_name;
266 }
267 else {
268 name = sec_name(sym->st_shndx);
269 }
270 return name;
271}
272
273static Elf_Sym *sym_lookup(const char *symname)
274{
275 int i;
276 for (i = 0; i < shnum; i++) {
277 struct section *sec = &secs[i];
278 long nsyms;
279 char *strtab;
280 Elf_Sym *symtab;
281 Elf_Sym *sym;
282
283 if (sec->shdr.sh_type != SHT_SYMTAB)
284 continue;
285
286 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
287 symtab = sec->symtab;
288 strtab = sec->link->strtab;
289
290 for (sym = symtab; --nsyms >= 0; sym++) {
291 if (!sym->st_name)
292 continue;
293 if (strcmp(symname, strtab + sym->st_name) == 0)
294 return sym;
295 }
296 }
297 return 0;
298}
299
300#if BYTE_ORDER == LITTLE_ENDIAN
301#define le16_to_cpu(val) (val)
302#define le32_to_cpu(val) (val)
303#define le64_to_cpu(val) (val)
304#endif
305#if BYTE_ORDER == BIG_ENDIAN
306#define le16_to_cpu(val) bswap_16(val)
307#define le32_to_cpu(val) bswap_32(val)
308#define le64_to_cpu(val) bswap_64(val)
309#endif
310
311static uint16_t elf16_to_cpu(uint16_t val)
312{
313 return le16_to_cpu(val);
314}
315
316static uint32_t elf32_to_cpu(uint32_t val)
317{
318 return le32_to_cpu(val);
319}
320
321#define elf_half_to_cpu(x) elf16_to_cpu(x)
322#define elf_word_to_cpu(x) elf32_to_cpu(x)
323
324#if ELF_BITS == 64
325static uint64_t elf64_to_cpu(uint64_t val)
326{
327 return le64_to_cpu(val);
328}
329#define elf_addr_to_cpu(x) elf64_to_cpu(x)
330#define elf_off_to_cpu(x) elf64_to_cpu(x)
331#define elf_xword_to_cpu(x) elf64_to_cpu(x)
332#else
333#define elf_addr_to_cpu(x) elf32_to_cpu(x)
334#define elf_off_to_cpu(x) elf32_to_cpu(x)
335#define elf_xword_to_cpu(x) elf32_to_cpu(x)
336#endif
337
338static void read_ehdr(FILE *fp)
339{
340 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
341 die("Cannot read ELF header: %s\n",
342 strerror(errno));
343 }
344 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
345 die("No ELF magic\n");
346 }
347 if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
348 die("Not a %d bit executable\n", ELF_BITS);
349 }
350 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
351 die("Not a LSB ELF executable\n");
352 }
353 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
354 die("Unknown ELF version\n");
355 }
356 /* Convert the fields to native endian */
357 ehdr.e_type = elf_half_to_cpu(ehdr.e_type);
358 ehdr.e_machine = elf_half_to_cpu(ehdr.e_machine);
359 ehdr.e_version = elf_word_to_cpu(ehdr.e_version);
360 ehdr.e_entry = elf_addr_to_cpu(ehdr.e_entry);
361 ehdr.e_phoff = elf_off_to_cpu(ehdr.e_phoff);
362 ehdr.e_shoff = elf_off_to_cpu(ehdr.e_shoff);
363 ehdr.e_flags = elf_word_to_cpu(ehdr.e_flags);
364 ehdr.e_ehsize = elf_half_to_cpu(ehdr.e_ehsize);
365 ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
366 ehdr.e_phnum = elf_half_to_cpu(ehdr.e_phnum);
367 ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
368 ehdr.e_shnum = elf_half_to_cpu(ehdr.e_shnum);
369 ehdr.e_shstrndx = elf_half_to_cpu(ehdr.e_shstrndx);
370
371 shnum = ehdr.e_shnum;
372 shstrndx = ehdr.e_shstrndx;
373
374 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN))
375 die("Unsupported ELF header type\n");
376 if (ehdr.e_machine != ELF_MACHINE)
377 die("Not for %s\n", ELF_MACHINE_NAME);
378 if (ehdr.e_version != EV_CURRENT)
379 die("Unknown ELF version\n");
380 if (ehdr.e_ehsize != sizeof(Elf_Ehdr))
381 die("Bad Elf header size\n");
382 if (ehdr.e_phentsize != sizeof(Elf_Phdr))
383 die("Bad program header entry\n");
384 if (ehdr.e_shentsize != sizeof(Elf_Shdr))
385 die("Bad section header entry\n");
386
387
388 if (shnum == SHN_UNDEF || shstrndx == SHN_XINDEX) {
389 Elf_Shdr shdr;
390
391 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0)
392 die("Seek to %d failed: %s\n", ehdr.e_shoff, strerror(errno));
393
394 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
395 die("Cannot read initial ELF section header: %s\n", strerror(errno));
396
397 if (shnum == SHN_UNDEF)
398 shnum = elf_xword_to_cpu(shdr.sh_size);
399
400 if (shstrndx == SHN_XINDEX)
401 shstrndx = elf_word_to_cpu(shdr.sh_link);
402 }
403
404 if (shstrndx >= shnum)
405 die("String table index out of bounds\n");
406}
407
408static void read_shdrs(FILE *fp)
409{
410 int i;
411 Elf_Shdr shdr;
412
413 secs = calloc(shnum, sizeof(struct section));
414 if (!secs) {
415 die("Unable to allocate %d section headers\n",
416 shnum);
417 }
418 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
419 die("Seek to %d failed: %s\n",
420 ehdr.e_shoff, strerror(errno));
421 }
422 for (i = 0; i < shnum; i++) {
423 struct section *sec = &secs[i];
424 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
425 die("Cannot read ELF section headers %d/%d: %s\n",
426 i, shnum, strerror(errno));
427 sec->shdr.sh_name = elf_word_to_cpu(shdr.sh_name);
428 sec->shdr.sh_type = elf_word_to_cpu(shdr.sh_type);
429 sec->shdr.sh_flags = elf_xword_to_cpu(shdr.sh_flags);
430 sec->shdr.sh_addr = elf_addr_to_cpu(shdr.sh_addr);
431 sec->shdr.sh_offset = elf_off_to_cpu(shdr.sh_offset);
432 sec->shdr.sh_size = elf_xword_to_cpu(shdr.sh_size);
433 sec->shdr.sh_link = elf_word_to_cpu(shdr.sh_link);
434 sec->shdr.sh_info = elf_word_to_cpu(shdr.sh_info);
435 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
436 sec->shdr.sh_entsize = elf_xword_to_cpu(shdr.sh_entsize);
437 if (sec->shdr.sh_link < shnum)
438 sec->link = &secs[sec->shdr.sh_link];
439 }
440
441}
442
443static void read_strtabs(FILE *fp)
444{
445 int i;
446 for (i = 0; i < shnum; i++) {
447 struct section *sec = &secs[i];
448 if (sec->shdr.sh_type != SHT_STRTAB) {
449 continue;
450 }
451 sec->strtab = malloc(sec->shdr.sh_size);
452 if (!sec->strtab) {
453 die("malloc of %d bytes for strtab failed\n",
454 sec->shdr.sh_size);
455 }
456 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
457 die("Seek to %d failed: %s\n",
458 sec->shdr.sh_offset, strerror(errno));
459 }
460 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
461 != sec->shdr.sh_size) {
462 die("Cannot read symbol table: %s\n",
463 strerror(errno));
464 }
465 }
466}
467
468static void read_symtabs(FILE *fp)
469{
470 int i,j;
471 for (i = 0; i < shnum; i++) {
472 struct section *sec = &secs[i];
473 if (sec->shdr.sh_type != SHT_SYMTAB) {
474 continue;
475 }
476 sec->symtab = malloc(sec->shdr.sh_size);
477 if (!sec->symtab) {
478 die("malloc of %d bytes for symtab failed\n",
479 sec->shdr.sh_size);
480 }
481 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
482 die("Seek to %d failed: %s\n",
483 sec->shdr.sh_offset, strerror(errno));
484 }
485 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
486 != sec->shdr.sh_size) {
487 die("Cannot read symbol table: %s\n",
488 strerror(errno));
489 }
490 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
491 Elf_Sym *sym = &sec->symtab[j];
492 sym->st_name = elf_word_to_cpu(sym->st_name);
493 sym->st_value = elf_addr_to_cpu(sym->st_value);
494 sym->st_size = elf_xword_to_cpu(sym->st_size);
495 sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
496 }
497 }
498}
499
500
501static void read_relocs(FILE *fp)
502{
503 int i,j;
504 for (i = 0; i < shnum; i++) {
505 struct section *sec = &secs[i];
506 if (sec->shdr.sh_type != SHT_REL_TYPE) {
507 continue;
508 }
509 sec->reltab = malloc(sec->shdr.sh_size);
510 if (!sec->reltab) {
511 die("malloc of %d bytes for relocs failed\n",
512 sec->shdr.sh_size);
513 }
514 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
515 die("Seek to %d failed: %s\n",
516 sec->shdr.sh_offset, strerror(errno));
517 }
518 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
519 != sec->shdr.sh_size) {
520 die("Cannot read symbol table: %s\n",
521 strerror(errno));
522 }
523 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
524 Elf_Rel *rel = &sec->reltab[j];
525 rel->r_offset = elf_addr_to_cpu(rel->r_offset);
526 rel->r_info = elf_xword_to_cpu(rel->r_info);
527#if (SHT_REL_TYPE == SHT_RELA)
528 rel->r_addend = elf_xword_to_cpu(rel->r_addend);
529#endif
530 }
531 }
532}
533
534
535static void print_absolute_symbols(void)
536{
537 int i;
538 const char *format;
539
540 if (ELF_BITS == 64)
541 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
542 else
543 format = "%5d %08"PRIx32" %5"PRId32" %10s %10s %12s %s\n";
544
545 printf("Absolute symbols\n");
546 printf(" Num: Value Size Type Bind Visibility Name\n");
547 for (i = 0; i < shnum; i++) {
548 struct section *sec = &secs[i];
549 char *sym_strtab;
550 int j;
551
552 if (sec->shdr.sh_type != SHT_SYMTAB) {
553 continue;
554 }
555 sym_strtab = sec->link->strtab;
556 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
557 Elf_Sym *sym;
558 const char *name;
559 sym = &sec->symtab[j];
560 name = sym_name(sym_strtab, sym);
561 if (sym->st_shndx != SHN_ABS) {
562 continue;
563 }
564 printf(format,
565 j, sym->st_value, sym->st_size,
566 sym_type(ELF_ST_TYPE(sym->st_info)),
567 sym_bind(ELF_ST_BIND(sym->st_info)),
568 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
569 name);
570 }
571 }
572 printf("\n");
573}
574
575static void print_absolute_relocs(void)
576{
577 int i, printed = 0;
578 const char *format;
579
580 if (ELF_BITS == 64)
581 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64" %s\n";
582 else
583 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32" %s\n";
584
585 for (i = 0; i < shnum; i++) {
586 struct section *sec = &secs[i];
587 struct section *sec_applies, *sec_symtab;
588 char *sym_strtab;
589 Elf_Sym *sh_symtab;
590 int j;
591 if (sec->shdr.sh_type != SHT_REL_TYPE) {
592 continue;
593 }
594 sec_symtab = sec->link;
595 sec_applies = &secs[sec->shdr.sh_info];
596 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
597 continue;
598 }
599 sh_symtab = sec_symtab->symtab;
600 sym_strtab = sec_symtab->link->strtab;
601 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
602 Elf_Rel *rel;
603 Elf_Sym *sym;
604 const char *name;
605 rel = &sec->reltab[j];
606 sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
607 name = sym_name(sym_strtab, sym);
608 if (sym->st_shndx != SHN_ABS) {
609 continue;
610 }
611
612 /* Absolute symbols are not relocated if bzImage is
613 * loaded at a non-compiled address. Display a warning
614 * to user at compile time about the absolute
615 * relocations present.
616 *
617 * User need to audit the code to make sure
618 * some symbols which should have been section
619 * relative have not become absolute because of some
620 * linker optimization or wrong programming usage.
621 *
622 * Before warning check if this absolute symbol
623 * relocation is harmless.
624 */
625 if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
626 continue;
627
628 if (!printed) {
629 printf("WARNING: Absolute relocations"
630 " present\n");
631 printf("Offset Info Type Sym.Value "
632 "Sym.Name\n");
633 printed = 1;
634 }
635
636 printf(format,
637 rel->r_offset,
638 rel->r_info,
639 rel_type(ELF_R_TYPE(rel->r_info)),
640 sym->st_value,
641 name);
642 }
643 }
644
645 if (printed)
646 printf("\n");
647}
648
649static void add_reloc(struct relocs *r, uint32_t offset)
650{
651 if (r->count == r->size) {
652 unsigned long newsize = r->size + 50000;
653 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
654
655 if (!mem)
656 die("realloc of %ld entries for relocs failed\n",
657 newsize);
658 r->offset = mem;
659 r->size = newsize;
660 }
661 r->offset[r->count++] = offset;
662}
663
664static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
665 Elf_Sym *sym, const char *symname))
666{
667 int i;
668 /* Walk through the relocations */
669 for (i = 0; i < shnum; i++) {
670 char *sym_strtab;
671 Elf_Sym *sh_symtab;
672 struct section *sec_applies, *sec_symtab;
673 int j;
674 struct section *sec = &secs[i];
675
676 if (sec->shdr.sh_type != SHT_REL_TYPE) {
677 continue;
678 }
679 sec_symtab = sec->link;
680 sec_applies = &secs[sec->shdr.sh_info];
681 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
682 continue;
683 }
684 sh_symtab = sec_symtab->symtab;
685 sym_strtab = sec_symtab->link->strtab;
686 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
687 Elf_Rel *rel = &sec->reltab[j];
688 Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
689 const char *symname = sym_name(sym_strtab, sym);
690
691 process(sec, rel, sym, symname);
692 }
693 }
694}
695
696/*
697 * The .data..percpu section is a special case for x86_64 SMP kernels.
698 * It is used to initialize the actual per_cpu areas and to provide
699 * definitions for the per_cpu variables that correspond to their offsets
700 * within the percpu area. Since the values of all of the symbols need
701 * to be offsets from the start of the per_cpu area the virtual address
702 * (sh_addr) of .data..percpu is 0 in SMP kernels.
703 *
704 * This means that:
705 *
706 * Relocations that reference symbols in the per_cpu area do not
707 * need further relocation (since the value is an offset relative
708 * to the start of the per_cpu area that does not change).
709 *
710 * Relocations that apply to the per_cpu area need to have their
711 * offset adjusted by by the value of __per_cpu_load to make them
712 * point to the correct place in the loaded image (because the
713 * virtual address of .data..percpu is 0).
714 *
715 * For non SMP kernels .data..percpu is linked as part of the normal
716 * kernel data and does not require special treatment.
717 *
718 */
719static int per_cpu_shndx = -1;
720static Elf_Addr per_cpu_load_addr;
721
722static void percpu_init(void)
723{
724 int i;
725 for (i = 0; i < shnum; i++) {
726 ElfW(Sym) *sym;
727 if (strcmp(sec_name(i), ".data..percpu"))
728 continue;
729
730 if (secs[i].shdr.sh_addr != 0) /* non SMP kernel */
731 return;
732
733 sym = sym_lookup("__per_cpu_load");
734 if (!sym)
735 die("can't find __per_cpu_load\n");
736
737 per_cpu_shndx = i;
738 per_cpu_load_addr = sym->st_value;
739 return;
740 }
741}
742
743#if ELF_BITS == 64
744
745/*
746 * Check to see if a symbol lies in the .data..percpu section.
747 *
748 * The linker incorrectly associates some symbols with the
749 * .data..percpu section so we also need to check the symbol
750 * name to make sure that we classify the symbol correctly.
751 *
752 * The GNU linker incorrectly associates:
753 * __init_begin
754 * __per_cpu_load
755 *
756 * The "gold" linker incorrectly associates:
757 * init_per_cpu__fixed_percpu_data
758 * init_per_cpu__gdt_page
759 */
760static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
761{
762 return (sym->st_shndx == per_cpu_shndx) &&
763 strcmp(symname, "__init_begin") &&
764 strcmp(symname, "__per_cpu_load") &&
765 strncmp(symname, "init_per_cpu_", 13);
766}
767
768
769static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
770 const char *symname)
771{
772 unsigned r_type = ELF64_R_TYPE(rel->r_info);
773 ElfW(Addr) offset = rel->r_offset;
774 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
775
776 if (sym->st_shndx == SHN_UNDEF)
777 return 0;
778
779 /*
780 * Adjust the offset if this reloc applies to the percpu section.
781 */
782 if (sec->shdr.sh_info == per_cpu_shndx)
783 offset += per_cpu_load_addr;
784
785 switch (r_type) {
786 case R_X86_64_NONE:
787 /* NONE can be ignored. */
788 break;
789
790 case R_X86_64_PC32:
791 case R_X86_64_PLT32:
792 /*
793 * PC relative relocations don't need to be adjusted unless
794 * referencing a percpu symbol.
795 *
796 * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
797 */
798 if (is_percpu_sym(sym, symname))
799 add_reloc(&relocs32neg, offset);
800 break;
801
802 case R_X86_64_PC64:
803 /*
804 * Only used by jump labels
805 */
806 if (is_percpu_sym(sym, symname))
807 die("Invalid R_X86_64_PC64 relocation against per-CPU symbol %s\n",
808 symname);
809 break;
810
811 case R_X86_64_32:
812 case R_X86_64_32S:
813 case R_X86_64_64:
814 /*
815 * References to the percpu area don't need to be adjusted.
816 */
817 if (is_percpu_sym(sym, symname))
818 break;
819
820 if (shn_abs) {
821 /*
822 * Whitelisted absolute symbols do not require
823 * relocation.
824 */
825 if (is_reloc(S_ABS, symname))
826 break;
827
828 die("Invalid absolute %s relocation: %s\n",
829 rel_type(r_type), symname);
830 break;
831 }
832
833 /*
834 * Relocation offsets for 64 bit kernels are output
835 * as 32 bits and sign extended back to 64 bits when
836 * the relocations are processed.
837 * Make sure that the offset will fit.
838 */
839 if ((int32_t)offset != (int64_t)offset)
840 die("Relocation offset doesn't fit in 32 bits\n");
841
842 if (r_type == R_X86_64_64)
843 add_reloc(&relocs64, offset);
844 else
845 add_reloc(&relocs32, offset);
846 break;
847
848 default:
849 die("Unsupported relocation type: %s (%d)\n",
850 rel_type(r_type), r_type);
851 break;
852 }
853
854 return 0;
855}
856
857#else
858
859static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
860 const char *symname)
861{
862 unsigned r_type = ELF32_R_TYPE(rel->r_info);
863 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
864
865 switch (r_type) {
866 case R_386_NONE:
867 case R_386_PC32:
868 case R_386_PC16:
869 case R_386_PC8:
870 /*
871 * NONE can be ignored and PC relative relocations don't
872 * need to be adjusted.
873 */
874 break;
875
876 case R_386_32:
877 if (shn_abs) {
878 /*
879 * Whitelisted absolute symbols do not require
880 * relocation.
881 */
882 if (is_reloc(S_ABS, symname))
883 break;
884
885 die("Invalid absolute %s relocation: %s\n",
886 rel_type(r_type), symname);
887 break;
888 }
889
890 add_reloc(&relocs32, rel->r_offset);
891 break;
892
893 default:
894 die("Unsupported relocation type: %s (%d)\n",
895 rel_type(r_type), r_type);
896 break;
897 }
898
899 return 0;
900}
901
902static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
903 const char *symname)
904{
905 unsigned r_type = ELF32_R_TYPE(rel->r_info);
906 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
907
908 switch (r_type) {
909 case R_386_NONE:
910 case R_386_PC32:
911 case R_386_PC16:
912 case R_386_PC8:
913 /*
914 * NONE can be ignored and PC relative relocations don't
915 * need to be adjusted.
916 */
917 break;
918
919 case R_386_16:
920 if (shn_abs) {
921 /*
922 * Whitelisted absolute symbols do not require
923 * relocation.
924 */
925 if (is_reloc(S_ABS, symname))
926 break;
927
928 if (is_reloc(S_SEG, symname)) {
929 add_reloc(&relocs16, rel->r_offset);
930 break;
931 }
932 } else {
933 if (!is_reloc(S_LIN, symname))
934 break;
935 }
936 die("Invalid %s %s relocation: %s\n",
937 shn_abs ? "absolute" : "relative",
938 rel_type(r_type), symname);
939 break;
940
941 case R_386_32:
942 if (shn_abs) {
943 /*
944 * Whitelisted absolute symbols do not require
945 * relocation.
946 */
947 if (is_reloc(S_ABS, symname))
948 break;
949
950 if (is_reloc(S_REL, symname)) {
951 add_reloc(&relocs32, rel->r_offset);
952 break;
953 }
954 } else {
955 if (is_reloc(S_LIN, symname))
956 add_reloc(&relocs32, rel->r_offset);
957 break;
958 }
959 die("Invalid %s %s relocation: %s\n",
960 shn_abs ? "absolute" : "relative",
961 rel_type(r_type), symname);
962 break;
963
964 default:
965 die("Unsupported relocation type: %s (%d)\n",
966 rel_type(r_type), r_type);
967 break;
968 }
969
970 return 0;
971}
972
973#endif
974
975static int cmp_relocs(const void *va, const void *vb)
976{
977 const uint32_t *a, *b;
978 a = va; b = vb;
979 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
980}
981
982static void sort_relocs(struct relocs *r)
983{
984 qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
985}
986
987static int write32(uint32_t v, FILE *f)
988{
989 unsigned char buf[4];
990
991 put_unaligned_le32(v, buf);
992 return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
993}
994
995static int write32_as_text(uint32_t v, FILE *f)
996{
997 return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
998}
999
1000static void emit_relocs(int as_text, int use_real_mode)
1001{
1002 int i;
1003 int (*write_reloc)(uint32_t, FILE *) = write32;
1004 int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
1005 const char *symname);
1006
1007#if ELF_BITS == 64
1008 if (!use_real_mode)
1009 do_reloc = do_reloc64;
1010 else
1011 die("--realmode not valid for a 64-bit ELF file");
1012#else
1013 if (!use_real_mode)
1014 do_reloc = do_reloc32;
1015 else
1016 do_reloc = do_reloc_real;
1017#endif
1018
1019 /* Collect up the relocations */
1020 walk_relocs(do_reloc);
1021
1022 if (relocs16.count && !use_real_mode)
1023 die("Segment relocations found but --realmode not specified\n");
1024
1025 /* Order the relocations for more efficient processing */
1026 sort_relocs(&relocs32);
1027#if ELF_BITS == 64
1028 sort_relocs(&relocs32neg);
1029 sort_relocs(&relocs64);
1030#else
1031 sort_relocs(&relocs16);
1032#endif
1033
1034 /* Print the relocations */
1035 if (as_text) {
1036 /* Print the relocations in a form suitable that
1037 * gas will like.
1038 */
1039 printf(".section \".data.reloc\",\"a\"\n");
1040 printf(".balign 4\n");
1041 write_reloc = write32_as_text;
1042 }
1043
1044 if (use_real_mode) {
1045 write_reloc(relocs16.count, stdout);
1046 for (i = 0; i < relocs16.count; i++)
1047 write_reloc(relocs16.offset[i], stdout);
1048
1049 write_reloc(relocs32.count, stdout);
1050 for (i = 0; i < relocs32.count; i++)
1051 write_reloc(relocs32.offset[i], stdout);
1052 } else {
1053#if ELF_BITS == 64
1054 /* Print a stop */
1055 write_reloc(0, stdout);
1056
1057 /* Now print each relocation */
1058 for (i = 0; i < relocs64.count; i++)
1059 write_reloc(relocs64.offset[i], stdout);
1060
1061 /* Print a stop */
1062 write_reloc(0, stdout);
1063
1064 /* Now print each inverse 32-bit relocation */
1065 for (i = 0; i < relocs32neg.count; i++)
1066 write_reloc(relocs32neg.offset[i], stdout);
1067#endif
1068
1069 /* Print a stop */
1070 write_reloc(0, stdout);
1071
1072 /* Now print each relocation */
1073 for (i = 0; i < relocs32.count; i++)
1074 write_reloc(relocs32.offset[i], stdout);
1075 }
1076}
1077
1078/*
1079 * As an aid to debugging problems with different linkers
1080 * print summary information about the relocs.
1081 * Since different linkers tend to emit the sections in
1082 * different orders we use the section names in the output.
1083 */
1084static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1085 const char *symname)
1086{
1087 printf("%s\t%s\t%s\t%s\n",
1088 sec_name(sec->shdr.sh_info),
1089 rel_type(ELF_R_TYPE(rel->r_info)),
1090 symname,
1091 sec_name(sym->st_shndx));
1092 return 0;
1093}
1094
1095static void print_reloc_info(void)
1096{
1097 printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1098 walk_relocs(do_reloc_info);
1099}
1100
1101#if ELF_BITS == 64
1102# define process process_64
1103#else
1104# define process process_32
1105#endif
1106
1107void process(FILE *fp, int use_real_mode, int as_text,
1108 int show_absolute_syms, int show_absolute_relocs,
1109 int show_reloc_info)
1110{
1111 regex_init(use_real_mode);
1112 read_ehdr(fp);
1113 read_shdrs(fp);
1114 read_strtabs(fp);
1115 read_symtabs(fp);
1116 read_relocs(fp);
1117 if (ELF_BITS == 64)
1118 percpu_init();
1119 if (show_absolute_syms) {
1120 print_absolute_symbols();
1121 return;
1122 }
1123 if (show_absolute_relocs) {
1124 print_absolute_relocs();
1125 return;
1126 }
1127 if (show_reloc_info) {
1128 print_reloc_info();
1129 return;
1130 }
1131 emit_relocs(as_text, use_real_mode);
1132}