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 static unsigned long shnum;
16 static unsigned int shstrndx;
17 static unsigned int shsymtabndx;
18 static unsigned int shxsymtabndx;
19
20 static int sym_index(Elf_Sym *sym);
21
22 struct relocs {
23 uint32_t *offset;
24 unsigned long count;
25 unsigned long size;
26 };
27
28 static struct relocs relocs16;
29 static struct relocs relocs32;
30
31 #if ELF_BITS == 64
32 static struct relocs relocs32neg;
33 static struct relocs relocs64;
34 # define FMT PRIu64
35 #else
36 # define FMT PRIu32
37 #endif
38
39 struct section {
40 Elf_Shdr shdr;
41 struct section *link;
42 Elf_Sym *symtab;
43 Elf32_Word *xsymtab;
44 Elf_Rel *reltab;
45 char *strtab;
46 };
47 static struct section *secs;
48
49 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
50 /*
51 * Following symbols have been audited. There values are constant and do
52 * not change if bzImage is loaded at a different physical address than
53 * the address for which it has been compiled. Don't warn user about
54 * absolute relocations present w.r.t these symbols.
55 */
56 [S_ABS] =
57 "^(xen_irq_disable_direct_reloc$|"
58 "xen_save_fl_direct_reloc$|"
59 "VDSO|"
60 "__kcfi_typeid_|"
61 "__crc_)",
62
63 /*
64 * These symbols are known to be relative, even if the linker marks them
65 * as absolute (typically defined outside any section in the linker script.)
66 */
67 [S_REL] =
68 "^(__init_(begin|end)|"
69 "__x86_cpu_dev_(start|end)|"
70 "__alt_instructions(_end)?|"
71 "(__iommu_table|__apicdrivers|__smp_locks)(_end)?|"
72 "__(start|end)_pci_.*|"
73 #if CONFIG_FW_LOADER
74 "__(start|end)_builtin_fw|"
75 #endif
76 "__(start|stop)___ksymtab(_gpl)?|"
77 "__(start|stop)___kcrctab(_gpl)?|"
78 "__(start|stop)___param|"
79 "__(start|stop)___modver|"
80 "__(start|stop)___bug_table|"
81 "__tracedata_(start|end)|"
82 "__(start|stop)_notes|"
83 "__end_rodata|"
84 "__end_rodata_aligned|"
85 "__initramfs_start|"
86 "(jiffies|jiffies_64)|"
87 #if ELF_BITS == 64
88 "__per_cpu_load|"
89 "init_per_cpu__.*|"
90 "__end_rodata_hpage_align|"
91 #endif
92 "__vvar_page|"
93 "_end)$"
94 };
95
96
97 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
98 /*
99 * These symbols are known to be relative, even if the linker marks them
100 * as absolute (typically defined outside any section in the linker script.)
101 */
102 [S_REL] =
103 "^pa_",
104
105 /*
106 * These are 16-bit segment symbols when compiling 16-bit code.
107 */
108 [S_SEG] =
109 "^real_mode_seg$",
110
111 /*
112 * These are offsets belonging to segments, as opposed to linear addresses,
113 * when compiling 16-bit code.
114 */
115 [S_LIN] =
116 "^pa_",
117 };
118
119 static const char * const *sym_regex;
120
121 static regex_t sym_regex_c[S_NSYMTYPES];
122
123 static int is_reloc(enum symtype type, const char *sym_name)
124 {
125 return sym_regex[type] && !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
126 }
127
128 static void regex_init(int use_real_mode)
129 {
130 char errbuf[128];
131 int err;
132 int i;
133
134 if (use_real_mode)
135 sym_regex = sym_regex_realmode;
136 else
137 sym_regex = sym_regex_kernel;
138
139 for (i = 0; i < S_NSYMTYPES; i++) {
140 if (!sym_regex[i])
141 continue;
142
143 err = regcomp(&sym_regex_c[i], sym_regex[i], REG_EXTENDED|REG_NOSUB);
144
145 if (err) {
146 regerror(err, &sym_regex_c[i], errbuf, sizeof(errbuf));
147 die("%s", errbuf);
148 }
149 }
150 }
151
152 static const char *sym_type(unsigned type)
153 {
154 static const char *type_name[] = {
155 #define SYM_TYPE(X) [X] = #X
156 SYM_TYPE(STT_NOTYPE),
157 SYM_TYPE(STT_OBJECT),
158 SYM_TYPE(STT_FUNC),
159 SYM_TYPE(STT_SECTION),
160 SYM_TYPE(STT_FILE),
161 SYM_TYPE(STT_COMMON),
162 SYM_TYPE(STT_TLS),
163 #undef SYM_TYPE
164 };
165 const char *name = "unknown sym type name";
166
167 if (type < ARRAY_SIZE(type_name))
168 name = type_name[type];
169
170 return name;
171 }
172
173 static const char *sym_bind(unsigned bind)
174 {
175 static const char *bind_name[] = {
176 #define SYM_BIND(X) [X] = #X
177 SYM_BIND(STB_LOCAL),
178 SYM_BIND(STB_GLOBAL),
179 SYM_BIND(STB_WEAK),
180 #undef SYM_BIND
181 };
182 const char *name = "unknown sym bind name";
183
184 if (bind < ARRAY_SIZE(bind_name))
185 name = bind_name[bind];
186
187 return name;
188 }
189
190 static const char *sym_visibility(unsigned visibility)
191 {
192 static const char *visibility_name[] = {
193 #define SYM_VISIBILITY(X) [X] = #X
194 SYM_VISIBILITY(STV_DEFAULT),
195 SYM_VISIBILITY(STV_INTERNAL),
196 SYM_VISIBILITY(STV_HIDDEN),
197 SYM_VISIBILITY(STV_PROTECTED),
198 #undef SYM_VISIBILITY
199 };
200 const char *name = "unknown sym visibility name";
201
202 if (visibility < ARRAY_SIZE(visibility_name))
203 name = visibility_name[visibility];
204
205 return name;
206 }
207
208 static const char *rel_type(unsigned type)
209 {
210 static const char *type_name[] = {
211 #define REL_TYPE(X) [X] = #X
212 #if ELF_BITS == 64
213 REL_TYPE(R_X86_64_NONE),
214 REL_TYPE(R_X86_64_64),
215 REL_TYPE(R_X86_64_PC64),
216 REL_TYPE(R_X86_64_PC32),
217 REL_TYPE(R_X86_64_GOT32),
218 REL_TYPE(R_X86_64_PLT32),
219 REL_TYPE(R_X86_64_COPY),
220 REL_TYPE(R_X86_64_GLOB_DAT),
221 REL_TYPE(R_X86_64_JUMP_SLOT),
222 REL_TYPE(R_X86_64_RELATIVE),
223 REL_TYPE(R_X86_64_GOTPCREL),
224 REL_TYPE(R_X86_64_32),
225 REL_TYPE(R_X86_64_32S),
226 REL_TYPE(R_X86_64_16),
227 REL_TYPE(R_X86_64_PC16),
228 REL_TYPE(R_X86_64_8),
229 REL_TYPE(R_X86_64_PC8),
230 #else
231 REL_TYPE(R_386_NONE),
232 REL_TYPE(R_386_32),
233 REL_TYPE(R_386_PC32),
234 REL_TYPE(R_386_GOT32),
235 REL_TYPE(R_386_PLT32),
236 REL_TYPE(R_386_COPY),
237 REL_TYPE(R_386_GLOB_DAT),
238 REL_TYPE(R_386_JMP_SLOT),
239 REL_TYPE(R_386_RELATIVE),
240 REL_TYPE(R_386_GOTOFF),
241 REL_TYPE(R_386_GOTPC),
242 REL_TYPE(R_386_8),
243 REL_TYPE(R_386_PC8),
244 REL_TYPE(R_386_16),
245 REL_TYPE(R_386_PC16),
246 #endif
247 #undef REL_TYPE
248 };
249 const char *name = "unknown type rel type name";
250
251 if (type < ARRAY_SIZE(type_name) && type_name[type])
252 name = type_name[type];
253
254 return name;
255 }
256
257 static const char *sec_name(unsigned shndx)
258 {
259 const char *sec_strtab;
260 const char *name;
261 sec_strtab = secs[shstrndx].strtab;
262 name = "<noname>";
263
264 if (shndx < shnum)
265 name = sec_strtab + secs[shndx].shdr.sh_name;
266 else if (shndx == SHN_ABS)
267 name = "ABSOLUTE";
268 else if (shndx == SHN_COMMON)
269 name = "COMMON";
270
271 return name;
272 }
273
274 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
275 {
276 const char *name;
277 name = "<noname>";
278
279 if (sym->st_name)
280 name = sym_strtab + sym->st_name;
281 else
282 name = sec_name(sym_index(sym));
283
284 return name;
285 }
286
287 static Elf_Sym *sym_lookup(const char *symname)
288 {
289 int i;
290
291 for (i = 0; i < shnum; i++) {
292 struct section *sec = &secs[i];
293 long nsyms;
294 char *strtab;
295 Elf_Sym *symtab;
296 Elf_Sym *sym;
297
298 if (sec->shdr.sh_type != SHT_SYMTAB)
299 continue;
300
301 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
302 symtab = sec->symtab;
303 strtab = sec->link->strtab;
304
305 for (sym = symtab; --nsyms >= 0; sym++) {
306 if (!sym->st_name)
307 continue;
308 if (strcmp(symname, strtab + sym->st_name) == 0)
309 return sym;
310 }
311 }
312 return 0;
313 }
314
315 #if BYTE_ORDER == LITTLE_ENDIAN
316 # define le16_to_cpu(val) (val)
317 # define le32_to_cpu(val) (val)
318 # define le64_to_cpu(val) (val)
319 #endif
320
321 #if BYTE_ORDER == BIG_ENDIAN
322 # define le16_to_cpu(val) bswap_16(val)
323 # define le32_to_cpu(val) bswap_32(val)
324 # define le64_to_cpu(val) bswap_64(val)
325 #endif
326
327 static uint16_t elf16_to_cpu(uint16_t val)
328 {
329 return le16_to_cpu(val);
330 }
331
332 static uint32_t elf32_to_cpu(uint32_t val)
333 {
334 return le32_to_cpu(val);
335 }
336
337 #define elf_half_to_cpu(x) elf16_to_cpu(x)
338 #define elf_word_to_cpu(x) elf32_to_cpu(x)
339
340 #if ELF_BITS == 64
341 static uint64_t elf64_to_cpu(uint64_t val)
342 {
343 return le64_to_cpu(val);
344 }
345 # define elf_addr_to_cpu(x) elf64_to_cpu(x)
346 # define elf_off_to_cpu(x) elf64_to_cpu(x)
347 # define elf_xword_to_cpu(x) elf64_to_cpu(x)
348 #else
349 # define elf_addr_to_cpu(x) elf32_to_cpu(x)
350 # define elf_off_to_cpu(x) elf32_to_cpu(x)
351 # define elf_xword_to_cpu(x) elf32_to_cpu(x)
352 #endif
353
354 static int sym_index(Elf_Sym *sym)
355 {
356 Elf_Sym *symtab = secs[shsymtabndx].symtab;
357 Elf32_Word *xsymtab = secs[shxsymtabndx].xsymtab;
358 unsigned long offset;
359 int index;
360
361 if (sym->st_shndx != SHN_XINDEX)
362 return sym->st_shndx;
363
364 /* calculate offset of sym from head of table. */
365 offset = (unsigned long)sym - (unsigned long)symtab;
366 index = offset / sizeof(*sym);
367
368 return elf32_to_cpu(xsymtab[index]);
369 }
370
371 static void read_ehdr(FILE *fp)
372 {
373 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1)
374 die("Cannot read ELF header: %s\n", strerror(errno));
375 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0)
376 die("No ELF magic\n");
377 if (ehdr.e_ident[EI_CLASS] != ELF_CLASS)
378 die("Not a %d bit executable\n", ELF_BITS);
379 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB)
380 die("Not a LSB ELF executable\n");
381 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT)
382 die("Unknown ELF version\n");
383
384 /* Convert the fields to native endian */
385 ehdr.e_type = elf_half_to_cpu(ehdr.e_type);
386 ehdr.e_machine = elf_half_to_cpu(ehdr.e_machine);
387 ehdr.e_version = elf_word_to_cpu(ehdr.e_version);
388 ehdr.e_entry = elf_addr_to_cpu(ehdr.e_entry);
389 ehdr.e_phoff = elf_off_to_cpu(ehdr.e_phoff);
390 ehdr.e_shoff = elf_off_to_cpu(ehdr.e_shoff);
391 ehdr.e_flags = elf_word_to_cpu(ehdr.e_flags);
392 ehdr.e_ehsize = elf_half_to_cpu(ehdr.e_ehsize);
393 ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
394 ehdr.e_phnum = elf_half_to_cpu(ehdr.e_phnum);
395 ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
396 ehdr.e_shnum = elf_half_to_cpu(ehdr.e_shnum);
397 ehdr.e_shstrndx = elf_half_to_cpu(ehdr.e_shstrndx);
398
399 shnum = ehdr.e_shnum;
400 shstrndx = ehdr.e_shstrndx;
401
402 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN))
403 die("Unsupported ELF header type\n");
404 if (ehdr.e_machine != ELF_MACHINE)
405 die("Not for %s\n", ELF_MACHINE_NAME);
406 if (ehdr.e_version != EV_CURRENT)
407 die("Unknown ELF version\n");
408 if (ehdr.e_ehsize != sizeof(Elf_Ehdr))
409 die("Bad ELF header size\n");
410 if (ehdr.e_phentsize != sizeof(Elf_Phdr))
411 die("Bad program header entry\n");
412 if (ehdr.e_shentsize != sizeof(Elf_Shdr))
413 die("Bad section header entry\n");
414
415
416 if (shnum == SHN_UNDEF || shstrndx == SHN_XINDEX) {
417 Elf_Shdr shdr;
418
419 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0)
420 die("Seek to %" FMT " failed: %s\n", ehdr.e_shoff, strerror(errno));
421
422 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
423 die("Cannot read initial ELF section header: %s\n", strerror(errno));
424
425 if (shnum == SHN_UNDEF)
426 shnum = elf_xword_to_cpu(shdr.sh_size);
427
428 if (shstrndx == SHN_XINDEX)
429 shstrndx = elf_word_to_cpu(shdr.sh_link);
430 }
431
432 if (shstrndx >= shnum)
433 die("String table index out of bounds\n");
434 }
435
436 static void read_shdrs(FILE *fp)
437 {
438 int i;
439 Elf_Shdr shdr;
440
441 secs = calloc(shnum, sizeof(struct section));
442 if (!secs)
443 die("Unable to allocate %ld section headers\n", shnum);
444
445 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0)
446 die("Seek to %" FMT " failed: %s\n", ehdr.e_shoff, strerror(errno));
447
448 for (i = 0; i < shnum; i++) {
449 struct section *sec = &secs[i];
450
451 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
452 die("Cannot read ELF section headers %d/%ld: %s\n", i, shnum, strerror(errno));
453
454 sec->shdr.sh_name = elf_word_to_cpu(shdr.sh_name);
455 sec->shdr.sh_type = elf_word_to_cpu(shdr.sh_type);
456 sec->shdr.sh_flags = elf_xword_to_cpu(shdr.sh_flags);
457 sec->shdr.sh_addr = elf_addr_to_cpu(shdr.sh_addr);
458 sec->shdr.sh_offset = elf_off_to_cpu(shdr.sh_offset);
459 sec->shdr.sh_size = elf_xword_to_cpu(shdr.sh_size);
460 sec->shdr.sh_link = elf_word_to_cpu(shdr.sh_link);
461 sec->shdr.sh_info = elf_word_to_cpu(shdr.sh_info);
462 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
463 sec->shdr.sh_entsize = elf_xword_to_cpu(shdr.sh_entsize);
464 if (sec->shdr.sh_link < shnum)
465 sec->link = &secs[sec->shdr.sh_link];
466 }
467
468 }
469
470 static void read_strtabs(FILE *fp)
471 {
472 int i;
473
474 for (i = 0; i < shnum; i++) {
475 struct section *sec = &secs[i];
476
477 if (sec->shdr.sh_type != SHT_STRTAB)
478 continue;
479
480 sec->strtab = malloc(sec->shdr.sh_size);
481 if (!sec->strtab)
482 die("malloc of %" FMT " bytes for strtab failed\n", sec->shdr.sh_size);
483
484 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
485 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
486
487 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
488 die("Cannot read symbol table: %s\n", strerror(errno));
489 }
490 }
491
492 static void read_symtabs(FILE *fp)
493 {
494 int i, j;
495
496 for (i = 0; i < shnum; i++) {
497 struct section *sec = &secs[i];
498 int num_syms;
499
500 switch (sec->shdr.sh_type) {
501 case SHT_SYMTAB_SHNDX:
502 sec->xsymtab = malloc(sec->shdr.sh_size);
503 if (!sec->xsymtab)
504 die("malloc of %" FMT " bytes for xsymtab failed\n", sec->shdr.sh_size);
505
506 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
507 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
508
509 if (fread(sec->xsymtab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
510 die("Cannot read extended symbol table: %s\n", strerror(errno));
511
512 shxsymtabndx = i;
513 continue;
514
515 case SHT_SYMTAB:
516 num_syms = sec->shdr.sh_size / sizeof(Elf_Sym);
517
518 sec->symtab = malloc(sec->shdr.sh_size);
519 if (!sec->symtab)
520 die("malloc of %" FMT " bytes for symtab failed\n", sec->shdr.sh_size);
521
522 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
523 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
524
525 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
526 die("Cannot read symbol table: %s\n", strerror(errno));
527
528 for (j = 0; j < num_syms; j++) {
529 Elf_Sym *sym = &sec->symtab[j];
530
531 sym->st_name = elf_word_to_cpu(sym->st_name);
532 sym->st_value = elf_addr_to_cpu(sym->st_value);
533 sym->st_size = elf_xword_to_cpu(sym->st_size);
534 sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
535 }
536 shsymtabndx = i;
537 continue;
538
539 default:
540 continue;
541 }
542 }
543 }
544
545
546 static void read_relocs(FILE *fp)
547 {
548 int i, j;
549
550 for (i = 0; i < shnum; i++) {
551 struct section *sec = &secs[i];
552
553 if (sec->shdr.sh_type != SHT_REL_TYPE)
554 continue;
555
556 sec->reltab = malloc(sec->shdr.sh_size);
557 if (!sec->reltab)
558 die("malloc of %" FMT " bytes for relocs failed\n", sec->shdr.sh_size);
559
560 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
561 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
562
563 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
564 die("Cannot read symbol table: %s\n", strerror(errno));
565
566 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
567 Elf_Rel *rel = &sec->reltab[j];
568
569 rel->r_offset = elf_addr_to_cpu(rel->r_offset);
570 rel->r_info = elf_xword_to_cpu(rel->r_info);
571 #if (SHT_REL_TYPE == SHT_RELA)
572 rel->r_addend = elf_xword_to_cpu(rel->r_addend);
573 #endif
574 }
575 }
576 }
577
578
579 static void print_absolute_symbols(void)
580 {
581 int i;
582 const char *format;
583
584 if (ELF_BITS == 64)
585 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
586 else
587 format = "%5d %08"PRIx32" %5"PRId32" %10s %10s %12s %s\n";
588
589 printf("Absolute symbols\n");
590 printf(" Num: Value Size Type Bind Visibility Name\n");
591
592 for (i = 0; i < shnum; i++) {
593 struct section *sec = &secs[i];
594 char *sym_strtab;
595 int j;
596
597 if (sec->shdr.sh_type != SHT_SYMTAB)
598 continue;
599
600 sym_strtab = sec->link->strtab;
601
602 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
603 Elf_Sym *sym;
604 const char *name;
605
606 sym = &sec->symtab[j];
607 name = sym_name(sym_strtab, sym);
608
609 if (sym->st_shndx != SHN_ABS)
610 continue;
611
612 printf(format,
613 j, sym->st_value, sym->st_size,
614 sym_type(ELF_ST_TYPE(sym->st_info)),
615 sym_bind(ELF_ST_BIND(sym->st_info)),
616 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
617 name);
618 }
619 }
620 printf("\n");
621 }
622
623 static void print_absolute_relocs(void)
624 {
625 int i, printed = 0;
626 const char *format;
627
628 if (ELF_BITS == 64)
629 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64" %s\n";
630 else
631 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32" %s\n";
632
633 for (i = 0; i < shnum; i++) {
634 struct section *sec = &secs[i];
635 struct section *sec_applies, *sec_symtab;
636 char *sym_strtab;
637 Elf_Sym *sh_symtab;
638 int j;
639
640 if (sec->shdr.sh_type != SHT_REL_TYPE)
641 continue;
642
643 sec_symtab = sec->link;
644 sec_applies = &secs[sec->shdr.sh_info];
645 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC))
646 continue;
647
648 /*
649 * Do not perform relocations in .notes section; any
650 * values there are meant for pre-boot consumption (e.g.
651 * startup_xen).
652 */
653 if (sec_applies->shdr.sh_type == SHT_NOTE)
654 continue;
655
656 sh_symtab = sec_symtab->symtab;
657 sym_strtab = sec_symtab->link->strtab;
658
659 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
660 Elf_Rel *rel;
661 Elf_Sym *sym;
662 const char *name;
663
664 rel = &sec->reltab[j];
665 sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
666 name = sym_name(sym_strtab, sym);
667
668 if (sym->st_shndx != SHN_ABS)
669 continue;
670
671 /* Absolute symbols are not relocated if bzImage is
672 * loaded at a non-compiled address. Display a warning
673 * to user at compile time about the absolute
674 * relocations present.
675 *
676 * User need to audit the code to make sure
677 * some symbols which should have been section
678 * relative have not become absolute because of some
679 * linker optimization or wrong programming usage.
680 *
681 * Before warning check if this absolute symbol
682 * relocation is harmless.
683 */
684 if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
685 continue;
686
687 if (!printed) {
688 printf("WARNING: Absolute relocations present\n");
689 printf("Offset Info Type Sym.Value Sym.Name\n");
690 printed = 1;
691 }
692
693 printf(format,
694 rel->r_offset,
695 rel->r_info,
696 rel_type(ELF_R_TYPE(rel->r_info)),
697 sym->st_value,
698 name);
699 }
700 }
701
702 if (printed)
703 printf("\n");
704 }
705
706 static void add_reloc(struct relocs *r, uint32_t offset)
707 {
708 if (r->count == r->size) {
709 unsigned long newsize = r->size + 50000;
710 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
711
712 if (!mem)
713 die("realloc of %ld entries for relocs failed\n", newsize);
714
715 r->offset = mem;
716 r->size = newsize;
717 }
718 r->offset[r->count++] = offset;
719 }
720
721 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
722 Elf_Sym *sym, const char *symname))
723 {
724 int i;
725
726 /* Walk through the relocations */
727 for (i = 0; i < shnum; i++) {
728 char *sym_strtab;
729 Elf_Sym *sh_symtab;
730 struct section *sec_applies, *sec_symtab;
731 int j;
732 struct section *sec = &secs[i];
733
734 if (sec->shdr.sh_type != SHT_REL_TYPE)
735 continue;
736
737 sec_symtab = sec->link;
738 sec_applies = &secs[sec->shdr.sh_info];
739 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC))
740 continue;
741
742 /*
743 * Do not perform relocations in .notes sections; any
744 * values there are meant for pre-boot consumption (e.g.
745 * startup_xen).
746 */
747 if (sec_applies->shdr.sh_type == SHT_NOTE)
748 continue;
749
750 sh_symtab = sec_symtab->symtab;
751 sym_strtab = sec_symtab->link->strtab;
752
753 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
754 Elf_Rel *rel = &sec->reltab[j];
755 Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
756 const char *symname = sym_name(sym_strtab, sym);
757
758 process(sec, rel, sym, symname);
759 }
760 }
761 }
762
763 /*
764 * The .data..percpu section is a special case for x86_64 SMP kernels.
765 * It is used to initialize the actual per_cpu areas and to provide
766 * definitions for the per_cpu variables that correspond to their offsets
767 * within the percpu area. Since the values of all of the symbols need
768 * to be offsets from the start of the per_cpu area the virtual address
769 * (sh_addr) of .data..percpu is 0 in SMP kernels.
770 *
771 * This means that:
772 *
773 * Relocations that reference symbols in the per_cpu area do not
774 * need further relocation (since the value is an offset relative
775 * to the start of the per_cpu area that does not change).
776 *
777 * Relocations that apply to the per_cpu area need to have their
778 * offset adjusted by by the value of __per_cpu_load to make them
779 * point to the correct place in the loaded image (because the
780 * virtual address of .data..percpu is 0).
781 *
782 * For non SMP kernels .data..percpu is linked as part of the normal
783 * kernel data and does not require special treatment.
784 *
785 */
786 static int per_cpu_shndx = -1;
787 static Elf_Addr per_cpu_load_addr;
788
789 static void percpu_init(void)
790 {
791 int i;
792
793 for (i = 0; i < shnum; i++) {
794 ElfW(Sym) *sym;
795
796 if (strcmp(sec_name(i), ".data..percpu"))
797 continue;
798
799 if (secs[i].shdr.sh_addr != 0) /* non SMP kernel */
800 return;
801
802 sym = sym_lookup("__per_cpu_load");
803 if (!sym)
804 die("can't find __per_cpu_load\n");
805
806 per_cpu_shndx = i;
807 per_cpu_load_addr = sym->st_value;
808
809 return;
810 }
811 }
812
813 #if ELF_BITS == 64
814
815 /*
816 * Check to see if a symbol lies in the .data..percpu section.
817 *
818 * The linker incorrectly associates some symbols with the
819 * .data..percpu section so we also need to check the symbol
820 * name to make sure that we classify the symbol correctly.
821 *
822 * The GNU linker incorrectly associates:
823 * __init_begin
824 * __per_cpu_load
825 *
826 * The "gold" linker incorrectly associates:
827 * init_per_cpu__fixed_percpu_data
828 * init_per_cpu__gdt_page
829 */
830 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
831 {
832 int shndx = sym_index(sym);
833
834 return (shndx == per_cpu_shndx) &&
835 strcmp(symname, "__init_begin") &&
836 strcmp(symname, "__per_cpu_load") &&
837 strncmp(symname, "init_per_cpu_", 13);
838 }
839
840
841 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
842 const char *symname)
843 {
844 unsigned r_type = ELF64_R_TYPE(rel->r_info);
845 ElfW(Addr) offset = rel->r_offset;
846 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
847
848 if (sym->st_shndx == SHN_UNDEF)
849 return 0;
850
851 /*
852 * Adjust the offset if this reloc applies to the percpu section.
853 */
854 if (sec->shdr.sh_info == per_cpu_shndx)
855 offset += per_cpu_load_addr;
856
857 switch (r_type) {
858 case R_X86_64_NONE:
859 /* NONE can be ignored. */
860 break;
861
862 case R_X86_64_PC32:
863 case R_X86_64_PLT32:
864 /*
865 * PC relative relocations don't need to be adjusted unless
866 * referencing a percpu symbol.
867 *
868 * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
869 */
870 if (is_percpu_sym(sym, symname))
871 add_reloc(&relocs32neg, offset);
872 break;
873
874 case R_X86_64_PC64:
875 /*
876 * Only used by jump labels
877 */
878 if (is_percpu_sym(sym, symname))
879 die("Invalid R_X86_64_PC64 relocation against per-CPU symbol %s\n", symname);
880 break;
881
882 case R_X86_64_32:
883 case R_X86_64_32S:
884 case R_X86_64_64:
885 /*
886 * References to the percpu area don't need to be adjusted.
887 */
888 if (is_percpu_sym(sym, symname))
889 break;
890
891 if (shn_abs) {
892 /*
893 * Whitelisted absolute symbols do not require
894 * relocation.
895 */
896 if (is_reloc(S_ABS, symname))
897 break;
898
899 die("Invalid absolute %s relocation: %s\n", rel_type(r_type), symname);
900 break;
901 }
902
903 /*
904 * Relocation offsets for 64 bit kernels are output
905 * as 32 bits and sign extended back to 64 bits when
906 * the relocations are processed.
907 * Make sure that the offset will fit.
908 */
909 if ((int32_t)offset != (int64_t)offset)
910 die("Relocation offset doesn't fit in 32 bits\n");
911
912 if (r_type == R_X86_64_64)
913 add_reloc(&relocs64, offset);
914 else
915 add_reloc(&relocs32, offset);
916 break;
917
918 default:
919 die("Unsupported relocation type: %s (%d)\n", rel_type(r_type), r_type);
920 break;
921 }
922
923 return 0;
924 }
925
926 #else
927
928 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
929 const char *symname)
930 {
931 unsigned r_type = ELF32_R_TYPE(rel->r_info);
932 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
933
934 switch (r_type) {
935 case R_386_NONE:
936 case R_386_PC32:
937 case R_386_PC16:
938 case R_386_PC8:
939 case R_386_PLT32:
940 /*
941 * NONE can be ignored and PC relative relocations don't need
942 * to be adjusted. Because sym must be defined, R_386_PLT32 can
943 * be treated the same way as R_386_PC32.
944 */
945 break;
946
947 case R_386_32:
948 if (shn_abs) {
949 /*
950 * Whitelisted absolute symbols do not require
951 * relocation.
952 */
953 if (is_reloc(S_ABS, symname))
954 break;
955
956 die("Invalid absolute %s relocation: %s\n", rel_type(r_type), symname);
957 break;
958 }
959
960 add_reloc(&relocs32, rel->r_offset);
961 break;
962
963 default:
964 die("Unsupported relocation type: %s (%d)\n", rel_type(r_type), r_type);
965 break;
966 }
967
968 return 0;
969 }
970
971 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, const char *symname)
972 {
973 unsigned r_type = ELF32_R_TYPE(rel->r_info);
974 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
975
976 switch (r_type) {
977 case R_386_NONE:
978 case R_386_PC32:
979 case R_386_PC16:
980 case R_386_PC8:
981 case R_386_PLT32:
982 /*
983 * NONE can be ignored and PC relative relocations don't need
984 * to be adjusted. Because sym must be defined, R_386_PLT32 can
985 * be treated the same way as R_386_PC32.
986 */
987 break;
988
989 case R_386_16:
990 if (shn_abs) {
991 /*
992 * Whitelisted absolute symbols do not require
993 * relocation.
994 */
995 if (is_reloc(S_ABS, symname))
996 break;
997
998 if (is_reloc(S_SEG, symname)) {
999 add_reloc(&relocs16, rel->r_offset);
1000 break;
1001 }
1002 } else {
1003 if (!is_reloc(S_LIN, symname))
1004 break;
1005 }
1006 die("Invalid %s %s relocation: %s\n", shn_abs ? "absolute" : "relative", rel_type(r_type), symname);
1007 break;
1008
1009 case R_386_32:
1010 if (shn_abs) {
1011 /*
1012 * Whitelisted absolute symbols do not require
1013 * relocation.
1014 */
1015 if (is_reloc(S_ABS, symname))
1016 break;
1017
1018 if (is_reloc(S_REL, symname)) {
1019 add_reloc(&relocs32, rel->r_offset);
1020 break;
1021 }
1022 } else {
1023 if (is_reloc(S_LIN, symname))
1024 add_reloc(&relocs32, rel->r_offset);
1025 break;
1026 }
1027 die("Invalid %s %s relocation: %s\n", shn_abs ? "absolute" : "relative", rel_type(r_type), symname);
1028 break;
1029
1030 default:
1031 die("Unsupported relocation type: %s (%d)\n", rel_type(r_type), r_type);
1032 break;
1033 }
1034
1035 return 0;
1036 }
1037
1038 #endif
1039
1040 static int cmp_relocs(const void *va, const void *vb)
1041 {
1042 const uint32_t *a, *b;
1043
1044 a = va;
1045 b = vb;
1046
1047 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
1048 }
1049
1050 static void sort_relocs(struct relocs *r)
1051 {
1052 qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
1053 }
1054
1055 static int write32(uint32_t v, FILE *f)
1056 {
1057 unsigned char buf[4];
1058
1059 put_unaligned_le32(v, buf);
1060
1061 return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
1062 }
1063
1064 static int write32_as_text(uint32_t v, FILE *f)
1065 {
1066 return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
1067 }
1068
1069 static void emit_relocs(int as_text, int use_real_mode)
1070 {
1071 int i;
1072 int (*write_reloc)(uint32_t, FILE *) = write32;
1073 int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, const char *symname);
1074
1075 #if ELF_BITS == 64
1076 if (!use_real_mode)
1077 do_reloc = do_reloc64;
1078 else
1079 die("--realmode not valid for a 64-bit ELF file");
1080 #else
1081 if (!use_real_mode)
1082 do_reloc = do_reloc32;
1083 else
1084 do_reloc = do_reloc_real;
1085 #endif
1086
1087 /* Collect up the relocations */
1088 walk_relocs(do_reloc);
1089
1090 if (relocs16.count && !use_real_mode)
1091 die("Segment relocations found but --realmode not specified\n");
1092
1093 /* Order the relocations for more efficient processing */
1094 sort_relocs(&relocs32);
1095 #if ELF_BITS == 64
1096 sort_relocs(&relocs32neg);
1097 sort_relocs(&relocs64);
1098 #else
1099 sort_relocs(&relocs16);
1100 #endif
1101
1102 /* Print the relocations */
1103 if (as_text) {
1104 /* Print the relocations in a form suitable that
1105 * gas will like.
1106 */
1107 printf(".section \".data.reloc\",\"a\"\n");
1108 printf(".balign 4\n");
1109 write_reloc = write32_as_text;
1110 }
1111
1112 if (use_real_mode) {
1113 write_reloc(relocs16.count, stdout);
1114 for (i = 0; i < relocs16.count; i++)
1115 write_reloc(relocs16.offset[i], stdout);
1116
1117 write_reloc(relocs32.count, stdout);
1118 for (i = 0; i < relocs32.count; i++)
1119 write_reloc(relocs32.offset[i], stdout);
1120 } else {
1121 #if ELF_BITS == 64
1122 /* Print a stop */
1123 write_reloc(0, stdout);
1124
1125 /* Now print each relocation */
1126 for (i = 0; i < relocs64.count; i++)
1127 write_reloc(relocs64.offset[i], stdout);
1128
1129 /* Print a stop */
1130 write_reloc(0, stdout);
1131
1132 /* Now print each inverse 32-bit relocation */
1133 for (i = 0; i < relocs32neg.count; i++)
1134 write_reloc(relocs32neg.offset[i], stdout);
1135 #endif
1136
1137 /* Print a stop */
1138 write_reloc(0, stdout);
1139
1140 /* Now print each relocation */
1141 for (i = 0; i < relocs32.count; i++)
1142 write_reloc(relocs32.offset[i], stdout);
1143 }
1144 }
1145
1146 /*
1147 * As an aid to debugging problems with different linkers
1148 * print summary information about the relocs.
1149 * Since different linkers tend to emit the sections in
1150 * different orders we use the section names in the output.
1151 */
1152 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1153 const char *symname)
1154 {
1155 printf("%s\t%s\t%s\t%s\n",
1156 sec_name(sec->shdr.sh_info),
1157 rel_type(ELF_R_TYPE(rel->r_info)),
1158 symname,
1159 sec_name(sym_index(sym)));
1160
1161 return 0;
1162 }
1163
1164 static void print_reloc_info(void)
1165 {
1166 printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1167 walk_relocs(do_reloc_info);
1168 }
1169
1170 #if ELF_BITS == 64
1171 # define process process_64
1172 #else
1173 # define process process_32
1174 #endif
1175
1176 void process(FILE *fp, int use_real_mode, int as_text,
1177 int show_absolute_syms, int show_absolute_relocs,
1178 int show_reloc_info)
1179 {
1180 regex_init(use_real_mode);
1181 read_ehdr(fp);
1182 read_shdrs(fp);
1183 read_strtabs(fp);
1184 read_symtabs(fp);
1185 read_relocs(fp);
1186
1187 if (ELF_BITS == 64)
1188 percpu_init();
1189
1190 if (show_absolute_syms) {
1191 print_absolute_symbols();
1192 return;
1193 }
1194
1195 if (show_absolute_relocs) {
1196 print_absolute_relocs();
1197 return;
1198 }
1199
1200 if (show_reloc_info) {
1201 print_reloc_info();
1202 return;
1203 }
1204
1205 emit_relocs(as_text, use_real_mode);
1206 }
1207
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