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 relocs64;
33 # define FMT PRIu64
34
35 #ifndef R_X86_64_REX_GOTPCRELX
36 # define R_X86_64_REX_GOTPCRELX 42
37 #endif
38
39 #else
40 # define FMT PRIu32
41 #endif
42
43 struct section {
44 Elf_Shdr shdr;
45 struct section *link;
46 Elf_Sym *symtab;
47 Elf32_Word *xsymtab;
48 Elf_Rel *reltab;
49 char *strtab;
50 };
51 static struct section *secs;
52
53 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
54 /*
55 * Following symbols have been audited. There values are constant and do
56 * not change if bzImage is loaded at a different physical address than
57 * the address for which it has been compiled. Don't warn user about
58 * absolute relocations present w.r.t these symbols.
59 */
60 [S_ABS] =
61 "^(xen_irq_disable_direct_reloc$|"
62 "xen_save_fl_direct_reloc$|"
63 "xen_elfnote_.+_offset$|"
64 "VDSO|"
65 "__kcfi_typeid_|"
66 "__crc_)",
67
68 /*
69 * These symbols are known to be relative, even if the linker marks them
70 * as absolute (typically defined outside any section in the linker script.)
71 */
72 [S_REL] =
73 "^(__init_(begin|end)|"
74 "__x86_cpu_dev_(start|end)|"
75 "__alt_instructions(_end)?|"
76 "(__iommu_table|__apicdrivers|__smp_locks)(_end)?|"
77 "__(start|end)_pci_.*|"
78 #if CONFIG_FW_LOADER
79 "__(start|end)_builtin_fw|"
80 #endif
81 "__(start|stop)___ksymtab(_gpl)?|"
82 "__(start|stop)___kcrctab(_gpl)?|"
83 "__(start|stop)___param|"
84 "__(start|stop)___modver|"
85 "__(start|stop)___bug_table|"
86 "__tracedata_(start|end)|"
87 "__(start|stop)_notes|"
88 "__end_rodata|"
89 "__end_rodata_aligned|"
90 "__initramfs_start|"
91 "(jiffies|jiffies_64)|"
92 #if ELF_BITS == 64
93 "__end_rodata_hpage_align|"
94 #endif
95 "_end)$"
96 };
97
98
99 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
100 /*
101 * These symbols are known to be relative, even if the linker marks them
102 * as absolute (typically defined outside any section in the linker script.)
103 */
104 [S_REL] =
105 "^pa_",
106
107 /*
108 * These are 16-bit segment symbols when compiling 16-bit code.
109 */
110 [S_SEG] =
111 "^real_mode_seg$",
112
113 /*
114 * These are offsets belonging to segments, as opposed to linear addresses,
115 * when compiling 16-bit code.
116 */
117 [S_LIN] =
118 "^pa_",
119 };
120
121 static const char * const *sym_regex;
122
123 static regex_t sym_regex_c[S_NSYMTYPES];
124
is_reloc(enum symtype type,const char * sym_name)125 static int is_reloc(enum symtype type, const char *sym_name)
126 {
127 return sym_regex[type] && !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
128 }
129
regex_init(int use_real_mode)130 static void regex_init(int use_real_mode)
131 {
132 char errbuf[128];
133 int err;
134 int i;
135
136 if (use_real_mode)
137 sym_regex = sym_regex_realmode;
138 else
139 sym_regex = sym_regex_kernel;
140
141 for (i = 0; i < S_NSYMTYPES; i++) {
142 if (!sym_regex[i])
143 continue;
144
145 err = regcomp(&sym_regex_c[i], sym_regex[i], REG_EXTENDED|REG_NOSUB);
146
147 if (err) {
148 regerror(err, &sym_regex_c[i], errbuf, sizeof(errbuf));
149 die("%s", errbuf);
150 }
151 }
152 }
153
sym_type(unsigned type)154 static const char *sym_type(unsigned type)
155 {
156 static const char *type_name[] = {
157 #define SYM_TYPE(X) [X] = #X
158 SYM_TYPE(STT_NOTYPE),
159 SYM_TYPE(STT_OBJECT),
160 SYM_TYPE(STT_FUNC),
161 SYM_TYPE(STT_SECTION),
162 SYM_TYPE(STT_FILE),
163 SYM_TYPE(STT_COMMON),
164 SYM_TYPE(STT_TLS),
165 #undef SYM_TYPE
166 };
167 const char *name = "unknown sym type name";
168
169 if (type < ARRAY_SIZE(type_name))
170 name = type_name[type];
171
172 return name;
173 }
174
sym_bind(unsigned bind)175 static const char *sym_bind(unsigned bind)
176 {
177 static const char *bind_name[] = {
178 #define SYM_BIND(X) [X] = #X
179 SYM_BIND(STB_LOCAL),
180 SYM_BIND(STB_GLOBAL),
181 SYM_BIND(STB_WEAK),
182 #undef SYM_BIND
183 };
184 const char *name = "unknown sym bind name";
185
186 if (bind < ARRAY_SIZE(bind_name))
187 name = bind_name[bind];
188
189 return name;
190 }
191
sym_visibility(unsigned visibility)192 static const char *sym_visibility(unsigned visibility)
193 {
194 static const char *visibility_name[] = {
195 #define SYM_VISIBILITY(X) [X] = #X
196 SYM_VISIBILITY(STV_DEFAULT),
197 SYM_VISIBILITY(STV_INTERNAL),
198 SYM_VISIBILITY(STV_HIDDEN),
199 SYM_VISIBILITY(STV_PROTECTED),
200 #undef SYM_VISIBILITY
201 };
202 const char *name = "unknown sym visibility name";
203
204 if (visibility < ARRAY_SIZE(visibility_name))
205 name = visibility_name[visibility];
206
207 return name;
208 }
209
rel_type(unsigned type)210 static const char *rel_type(unsigned type)
211 {
212 static const char *type_name[] = {
213 #define REL_TYPE(X) [X] = #X
214 #if ELF_BITS == 64
215 REL_TYPE(R_X86_64_NONE),
216 REL_TYPE(R_X86_64_64),
217 REL_TYPE(R_X86_64_PC64),
218 REL_TYPE(R_X86_64_PC32),
219 REL_TYPE(R_X86_64_GOT32),
220 REL_TYPE(R_X86_64_PLT32),
221 REL_TYPE(R_X86_64_COPY),
222 REL_TYPE(R_X86_64_GLOB_DAT),
223 REL_TYPE(R_X86_64_JUMP_SLOT),
224 REL_TYPE(R_X86_64_RELATIVE),
225 REL_TYPE(R_X86_64_GOTPCREL),
226 REL_TYPE(R_X86_64_32),
227 REL_TYPE(R_X86_64_32S),
228 REL_TYPE(R_X86_64_16),
229 REL_TYPE(R_X86_64_PC16),
230 REL_TYPE(R_X86_64_8),
231 REL_TYPE(R_X86_64_PC8),
232 REL_TYPE(R_X86_64_REX_GOTPCRELX),
233 #else
234 REL_TYPE(R_386_NONE),
235 REL_TYPE(R_386_32),
236 REL_TYPE(R_386_PC32),
237 REL_TYPE(R_386_GOT32),
238 REL_TYPE(R_386_PLT32),
239 REL_TYPE(R_386_COPY),
240 REL_TYPE(R_386_GLOB_DAT),
241 REL_TYPE(R_386_JMP_SLOT),
242 REL_TYPE(R_386_RELATIVE),
243 REL_TYPE(R_386_GOTOFF),
244 REL_TYPE(R_386_GOTPC),
245 REL_TYPE(R_386_8),
246 REL_TYPE(R_386_PC8),
247 REL_TYPE(R_386_16),
248 REL_TYPE(R_386_PC16),
249 #endif
250 #undef REL_TYPE
251 };
252 const char *name = "unknown type rel type name";
253
254 if (type < ARRAY_SIZE(type_name) && type_name[type])
255 name = type_name[type];
256
257 return name;
258 }
259
sec_name(unsigned shndx)260 static const char *sec_name(unsigned shndx)
261 {
262 const char *sec_strtab;
263 const char *name;
264 sec_strtab = secs[shstrndx].strtab;
265 name = "<noname>";
266
267 if (shndx < shnum)
268 name = sec_strtab + secs[shndx].shdr.sh_name;
269 else if (shndx == SHN_ABS)
270 name = "ABSOLUTE";
271 else if (shndx == SHN_COMMON)
272 name = "COMMON";
273
274 return name;
275 }
276
sym_name(const char * sym_strtab,Elf_Sym * sym)277 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
278 {
279 const char *name;
280 name = "<noname>";
281
282 if (sym->st_name)
283 name = sym_strtab + sym->st_name;
284 else
285 name = sec_name(sym_index(sym));
286
287 return name;
288 }
289
290 #if BYTE_ORDER == LITTLE_ENDIAN
291 # define le16_to_cpu(val) (val)
292 # define le32_to_cpu(val) (val)
293 # define le64_to_cpu(val) (val)
294 #endif
295
296 #if BYTE_ORDER == BIG_ENDIAN
297 # define le16_to_cpu(val) bswap_16(val)
298 # define le32_to_cpu(val) bswap_32(val)
299 # define le64_to_cpu(val) bswap_64(val)
300 #endif
301
elf16_to_cpu(uint16_t val)302 static uint16_t elf16_to_cpu(uint16_t val)
303 {
304 return le16_to_cpu(val);
305 }
306
elf32_to_cpu(uint32_t val)307 static uint32_t elf32_to_cpu(uint32_t val)
308 {
309 return le32_to_cpu(val);
310 }
311
312 #define elf_half_to_cpu(x) elf16_to_cpu(x)
313 #define elf_word_to_cpu(x) elf32_to_cpu(x)
314
315 #if ELF_BITS == 64
elf64_to_cpu(uint64_t val)316 static uint64_t elf64_to_cpu(uint64_t val)
317 {
318 return le64_to_cpu(val);
319 }
320 # define elf_addr_to_cpu(x) elf64_to_cpu(x)
321 # define elf_off_to_cpu(x) elf64_to_cpu(x)
322 # define elf_xword_to_cpu(x) elf64_to_cpu(x)
323 #else
324 # define elf_addr_to_cpu(x) elf32_to_cpu(x)
325 # define elf_off_to_cpu(x) elf32_to_cpu(x)
326 # define elf_xword_to_cpu(x) elf32_to_cpu(x)
327 #endif
328
sym_index(Elf_Sym * sym)329 static int sym_index(Elf_Sym *sym)
330 {
331 Elf_Sym *symtab = secs[shsymtabndx].symtab;
332 Elf32_Word *xsymtab = secs[shxsymtabndx].xsymtab;
333 unsigned long offset;
334 int index;
335
336 if (sym->st_shndx != SHN_XINDEX)
337 return sym->st_shndx;
338
339 /* calculate offset of sym from head of table. */
340 offset = (unsigned long)sym - (unsigned long)symtab;
341 index = offset / sizeof(*sym);
342
343 return elf32_to_cpu(xsymtab[index]);
344 }
345
read_ehdr(FILE * fp)346 static void read_ehdr(FILE *fp)
347 {
348 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1)
349 die("Cannot read ELF header: %s\n", strerror(errno));
350 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0)
351 die("No ELF magic\n");
352 if (ehdr.e_ident[EI_CLASS] != ELF_CLASS)
353 die("Not a %d bit executable\n", ELF_BITS);
354 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB)
355 die("Not a LSB ELF executable\n");
356 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT)
357 die("Unknown ELF version\n");
358
359 /* Convert the fields to native endian */
360 ehdr.e_type = elf_half_to_cpu(ehdr.e_type);
361 ehdr.e_machine = elf_half_to_cpu(ehdr.e_machine);
362 ehdr.e_version = elf_word_to_cpu(ehdr.e_version);
363 ehdr.e_entry = elf_addr_to_cpu(ehdr.e_entry);
364 ehdr.e_phoff = elf_off_to_cpu(ehdr.e_phoff);
365 ehdr.e_shoff = elf_off_to_cpu(ehdr.e_shoff);
366 ehdr.e_flags = elf_word_to_cpu(ehdr.e_flags);
367 ehdr.e_ehsize = elf_half_to_cpu(ehdr.e_ehsize);
368 ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
369 ehdr.e_phnum = elf_half_to_cpu(ehdr.e_phnum);
370 ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
371 ehdr.e_shnum = elf_half_to_cpu(ehdr.e_shnum);
372 ehdr.e_shstrndx = elf_half_to_cpu(ehdr.e_shstrndx);
373
374 shnum = ehdr.e_shnum;
375 shstrndx = ehdr.e_shstrndx;
376
377 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN))
378 die("Unsupported ELF header type\n");
379 if (ehdr.e_machine != ELF_MACHINE)
380 die("Not for %s\n", ELF_MACHINE_NAME);
381 if (ehdr.e_version != EV_CURRENT)
382 die("Unknown ELF version\n");
383 if (ehdr.e_ehsize != sizeof(Elf_Ehdr))
384 die("Bad ELF header size\n");
385 if (ehdr.e_phentsize != sizeof(Elf_Phdr))
386 die("Bad program header entry\n");
387 if (ehdr.e_shentsize != sizeof(Elf_Shdr))
388 die("Bad section header entry\n");
389
390
391 if (shnum == SHN_UNDEF || shstrndx == SHN_XINDEX) {
392 Elf_Shdr shdr;
393
394 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0)
395 die("Seek to %" FMT " failed: %s\n", ehdr.e_shoff, strerror(errno));
396
397 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
398 die("Cannot read initial ELF section header: %s\n", strerror(errno));
399
400 if (shnum == SHN_UNDEF)
401 shnum = elf_xword_to_cpu(shdr.sh_size);
402
403 if (shstrndx == SHN_XINDEX)
404 shstrndx = elf_word_to_cpu(shdr.sh_link);
405 }
406
407 if (shstrndx >= shnum)
408 die("String table index out of bounds\n");
409 }
410
read_shdrs(FILE * fp)411 static void read_shdrs(FILE *fp)
412 {
413 int i;
414 Elf_Shdr shdr;
415
416 secs = calloc(shnum, sizeof(struct section));
417 if (!secs)
418 die("Unable to allocate %ld section headers\n", shnum);
419
420 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0)
421 die("Seek to %" FMT " failed: %s\n", ehdr.e_shoff, strerror(errno));
422
423 for (i = 0; i < shnum; i++) {
424 struct section *sec = &secs[i];
425
426 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
427 die("Cannot read ELF section headers %d/%ld: %s\n", i, shnum, strerror(errno));
428
429 sec->shdr.sh_name = elf_word_to_cpu(shdr.sh_name);
430 sec->shdr.sh_type = elf_word_to_cpu(shdr.sh_type);
431 sec->shdr.sh_flags = elf_xword_to_cpu(shdr.sh_flags);
432 sec->shdr.sh_addr = elf_addr_to_cpu(shdr.sh_addr);
433 sec->shdr.sh_offset = elf_off_to_cpu(shdr.sh_offset);
434 sec->shdr.sh_size = elf_xword_to_cpu(shdr.sh_size);
435 sec->shdr.sh_link = elf_word_to_cpu(shdr.sh_link);
436 sec->shdr.sh_info = elf_word_to_cpu(shdr.sh_info);
437 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
438 sec->shdr.sh_entsize = elf_xword_to_cpu(shdr.sh_entsize);
439 if (sec->shdr.sh_link < shnum)
440 sec->link = &secs[sec->shdr.sh_link];
441 }
442
443 }
444
read_strtabs(FILE * fp)445 static void read_strtabs(FILE *fp)
446 {
447 int i;
448
449 for (i = 0; i < shnum; i++) {
450 struct section *sec = &secs[i];
451
452 if (sec->shdr.sh_type != SHT_STRTAB)
453 continue;
454
455 sec->strtab = malloc(sec->shdr.sh_size);
456 if (!sec->strtab)
457 die("malloc of %" FMT " bytes for strtab failed\n", sec->shdr.sh_size);
458
459 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
460 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
461
462 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
463 die("Cannot read symbol table: %s\n", strerror(errno));
464 }
465 }
466
read_symtabs(FILE * fp)467 static void read_symtabs(FILE *fp)
468 {
469 int i, j;
470
471 for (i = 0; i < shnum; i++) {
472 struct section *sec = &secs[i];
473 int num_syms;
474
475 switch (sec->shdr.sh_type) {
476 case SHT_SYMTAB_SHNDX:
477 sec->xsymtab = malloc(sec->shdr.sh_size);
478 if (!sec->xsymtab)
479 die("malloc of %" FMT " bytes for xsymtab failed\n", sec->shdr.sh_size);
480
481 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
482 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
483
484 if (fread(sec->xsymtab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
485 die("Cannot read extended symbol table: %s\n", strerror(errno));
486
487 shxsymtabndx = i;
488 continue;
489
490 case SHT_SYMTAB:
491 num_syms = sec->shdr.sh_size / sizeof(Elf_Sym);
492
493 sec->symtab = malloc(sec->shdr.sh_size);
494 if (!sec->symtab)
495 die("malloc of %" FMT " bytes for symtab failed\n", sec->shdr.sh_size);
496
497 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
498 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
499
500 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
501 die("Cannot read symbol table: %s\n", strerror(errno));
502
503 for (j = 0; j < num_syms; j++) {
504 Elf_Sym *sym = &sec->symtab[j];
505
506 sym->st_name = elf_word_to_cpu(sym->st_name);
507 sym->st_value = elf_addr_to_cpu(sym->st_value);
508 sym->st_size = elf_xword_to_cpu(sym->st_size);
509 sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
510 }
511 shsymtabndx = i;
512 continue;
513
514 default:
515 continue;
516 }
517 }
518 }
519
520
read_relocs(FILE * fp)521 static void read_relocs(FILE *fp)
522 {
523 int i, j;
524
525 for (i = 0; i < shnum; i++) {
526 struct section *sec = &secs[i];
527
528 if (sec->shdr.sh_type != SHT_REL_TYPE)
529 continue;
530
531 sec->reltab = malloc(sec->shdr.sh_size);
532 if (!sec->reltab)
533 die("malloc of %" FMT " bytes for relocs failed\n", sec->shdr.sh_size);
534
535 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0)
536 die("Seek to %" FMT " failed: %s\n", sec->shdr.sh_offset, strerror(errno));
537
538 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp) != sec->shdr.sh_size)
539 die("Cannot read symbol table: %s\n", strerror(errno));
540
541 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
542 Elf_Rel *rel = &sec->reltab[j];
543
544 rel->r_offset = elf_addr_to_cpu(rel->r_offset);
545 rel->r_info = elf_xword_to_cpu(rel->r_info);
546 #if (SHT_REL_TYPE == SHT_RELA)
547 rel->r_addend = elf_xword_to_cpu(rel->r_addend);
548 #endif
549 }
550 }
551 }
552
553
print_absolute_symbols(void)554 static void print_absolute_symbols(void)
555 {
556 int i;
557 const char *format;
558
559 if (ELF_BITS == 64)
560 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
561 else
562 format = "%5d %08"PRIx32" %5"PRId32" %10s %10s %12s %s\n";
563
564 printf("Absolute symbols\n");
565 printf(" Num: Value Size Type Bind Visibility Name\n");
566
567 for (i = 0; i < shnum; i++) {
568 struct section *sec = &secs[i];
569 char *sym_strtab;
570 int j;
571
572 if (sec->shdr.sh_type != SHT_SYMTAB)
573 continue;
574
575 sym_strtab = sec->link->strtab;
576
577 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
578 Elf_Sym *sym;
579 const char *name;
580
581 sym = &sec->symtab[j];
582 name = sym_name(sym_strtab, sym);
583
584 if (sym->st_shndx != SHN_ABS)
585 continue;
586
587 printf(format,
588 j, sym->st_value, sym->st_size,
589 sym_type(ELF_ST_TYPE(sym->st_info)),
590 sym_bind(ELF_ST_BIND(sym->st_info)),
591 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
592 name);
593 }
594 }
595 printf("\n");
596 }
597
print_absolute_relocs(void)598 static void print_absolute_relocs(void)
599 {
600 int i, printed = 0;
601 const char *format;
602
603 if (ELF_BITS == 64)
604 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64" %s\n";
605 else
606 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32" %s\n";
607
608 for (i = 0; i < shnum; i++) {
609 struct section *sec = &secs[i];
610 struct section *sec_applies, *sec_symtab;
611 char *sym_strtab;
612 Elf_Sym *sh_symtab;
613 int j;
614
615 if (sec->shdr.sh_type != SHT_REL_TYPE)
616 continue;
617
618 sec_symtab = sec->link;
619 sec_applies = &secs[sec->shdr.sh_info];
620 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC))
621 continue;
622
623 /*
624 * Do not perform relocations in .notes section; any
625 * values there are meant for pre-boot consumption (e.g.
626 * startup_xen).
627 */
628 if (sec_applies->shdr.sh_type == SHT_NOTE)
629 continue;
630
631 sh_symtab = sec_symtab->symtab;
632 sym_strtab = sec_symtab->link->strtab;
633
634 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
635 Elf_Rel *rel;
636 Elf_Sym *sym;
637 const char *name;
638
639 rel = &sec->reltab[j];
640 sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
641 name = sym_name(sym_strtab, sym);
642
643 if (sym->st_shndx != SHN_ABS)
644 continue;
645
646 /* Absolute symbols are not relocated if bzImage is
647 * loaded at a non-compiled address. Display a warning
648 * to user at compile time about the absolute
649 * relocations present.
650 *
651 * User need to audit the code to make sure
652 * some symbols which should have been section
653 * relative have not become absolute because of some
654 * linker optimization or wrong programming usage.
655 *
656 * Before warning check if this absolute symbol
657 * relocation is harmless.
658 */
659 if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
660 continue;
661
662 if (!printed) {
663 printf("WARNING: Absolute relocations present\n");
664 printf("Offset Info Type Sym.Value Sym.Name\n");
665 printed = 1;
666 }
667
668 printf(format,
669 rel->r_offset,
670 rel->r_info,
671 rel_type(ELF_R_TYPE(rel->r_info)),
672 sym->st_value,
673 name);
674 }
675 }
676
677 if (printed)
678 printf("\n");
679 }
680
add_reloc(struct relocs * r,uint32_t offset)681 static void add_reloc(struct relocs *r, uint32_t offset)
682 {
683 if (r->count == r->size) {
684 unsigned long newsize = r->size + 50000;
685 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
686
687 if (!mem)
688 die("realloc of %ld entries for relocs failed\n", newsize);
689
690 r->offset = mem;
691 r->size = newsize;
692 }
693 r->offset[r->count++] = offset;
694 }
695
walk_relocs(int (* process)(struct section * sec,Elf_Rel * rel,Elf_Sym * sym,const char * symname))696 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
697 Elf_Sym *sym, const char *symname))
698 {
699 int i;
700
701 /* Walk through the relocations */
702 for (i = 0; i < shnum; i++) {
703 char *sym_strtab;
704 Elf_Sym *sh_symtab;
705 struct section *sec_applies, *sec_symtab;
706 int j;
707 struct section *sec = &secs[i];
708
709 if (sec->shdr.sh_type != SHT_REL_TYPE)
710 continue;
711
712 sec_symtab = sec->link;
713 sec_applies = &secs[sec->shdr.sh_info];
714 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC))
715 continue;
716
717 /*
718 * Do not perform relocations in .notes sections; any
719 * values there are meant for pre-boot consumption (e.g.
720 * startup_xen).
721 */
722 if (sec_applies->shdr.sh_type == SHT_NOTE)
723 continue;
724
725 sh_symtab = sec_symtab->symtab;
726 sym_strtab = sec_symtab->link->strtab;
727
728 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
729 Elf_Rel *rel = &sec->reltab[j];
730 Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
731 const char *symname = sym_name(sym_strtab, sym);
732
733 process(sec, rel, sym, symname);
734 }
735 }
736 }
737
738 #if ELF_BITS == 64
739
do_reloc64(struct section * sec,Elf_Rel * rel,ElfW (Sym)* sym,const char * symname)740 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
741 const char *symname)
742 {
743 unsigned r_type = ELF64_R_TYPE(rel->r_info);
744 ElfW(Addr) offset = rel->r_offset;
745 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
746
747 if (sym->st_shndx == SHN_UNDEF)
748 return 0;
749
750 switch (r_type) {
751 case R_X86_64_NONE:
752 /* NONE can be ignored. */
753 break;
754
755 case R_X86_64_PC32:
756 case R_X86_64_PLT32:
757 case R_X86_64_REX_GOTPCRELX:
758 /*
759 * PC relative relocations don't need to be adjusted.
760 *
761 * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
762 */
763 break;
764
765 case R_X86_64_PC64:
766 /*
767 * Only used by jump labels
768 */
769 break;
770
771 case R_X86_64_32:
772 case R_X86_64_32S:
773 case R_X86_64_64:
774 if (shn_abs) {
775 /*
776 * Whitelisted absolute symbols do not require
777 * relocation.
778 */
779 if (is_reloc(S_ABS, symname))
780 break;
781
782 die("Invalid absolute %s relocation: %s\n", rel_type(r_type), symname);
783 break;
784 }
785
786 /*
787 * Relocation offsets for 64 bit kernels are output
788 * as 32 bits and sign extended back to 64 bits when
789 * the relocations are processed.
790 * Make sure that the offset will fit.
791 */
792 if ((int32_t)offset != (int64_t)offset)
793 die("Relocation offset doesn't fit in 32 bits\n");
794
795 if (r_type == R_X86_64_64)
796 add_reloc(&relocs64, offset);
797 else
798 add_reloc(&relocs32, offset);
799 break;
800
801 default:
802 die("Unsupported relocation type: %s (%d)\n", rel_type(r_type), r_type);
803 break;
804 }
805
806 return 0;
807 }
808
809 #else
810
do_reloc32(struct section * sec,Elf_Rel * rel,Elf_Sym * sym,const char * symname)811 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
812 const char *symname)
813 {
814 unsigned r_type = ELF32_R_TYPE(rel->r_info);
815 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
816
817 switch (r_type) {
818 case R_386_NONE:
819 case R_386_PC32:
820 case R_386_PC16:
821 case R_386_PC8:
822 case R_386_PLT32:
823 /*
824 * NONE can be ignored and PC relative relocations don't need
825 * to be adjusted. Because sym must be defined, R_386_PLT32 can
826 * be treated the same way as R_386_PC32.
827 */
828 break;
829
830 case R_386_32:
831 if (shn_abs) {
832 /*
833 * Whitelisted absolute symbols do not require
834 * relocation.
835 */
836 if (is_reloc(S_ABS, symname))
837 break;
838
839 die("Invalid absolute %s relocation: %s\n", rel_type(r_type), symname);
840 break;
841 }
842
843 add_reloc(&relocs32, rel->r_offset);
844 break;
845
846 default:
847 die("Unsupported relocation type: %s (%d)\n", rel_type(r_type), r_type);
848 break;
849 }
850
851 return 0;
852 }
853
do_reloc_real(struct section * sec,Elf_Rel * rel,Elf_Sym * sym,const char * symname)854 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, const char *symname)
855 {
856 unsigned r_type = ELF32_R_TYPE(rel->r_info);
857 int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
858
859 switch (r_type) {
860 case R_386_NONE:
861 case R_386_PC32:
862 case R_386_PC16:
863 case R_386_PC8:
864 case R_386_PLT32:
865 /*
866 * NONE can be ignored and PC relative relocations don't need
867 * to be adjusted. Because sym must be defined, R_386_PLT32 can
868 * be treated the same way as R_386_PC32.
869 */
870 break;
871
872 case R_386_16:
873 if (shn_abs) {
874 /*
875 * Whitelisted absolute symbols do not require
876 * relocation.
877 */
878 if (is_reloc(S_ABS, symname))
879 break;
880
881 if (is_reloc(S_SEG, symname)) {
882 add_reloc(&relocs16, rel->r_offset);
883 break;
884 }
885 } else {
886 if (!is_reloc(S_LIN, symname))
887 break;
888 }
889 die("Invalid %s %s relocation: %s\n", shn_abs ? "absolute" : "relative", rel_type(r_type), symname);
890 break;
891
892 case R_386_32:
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_REL, symname)) {
902 add_reloc(&relocs32, rel->r_offset);
903 break;
904 }
905 } else {
906 if (is_reloc(S_LIN, symname))
907 add_reloc(&relocs32, rel->r_offset);
908 break;
909 }
910 die("Invalid %s %s relocation: %s\n", shn_abs ? "absolute" : "relative", rel_type(r_type), symname);
911 break;
912
913 default:
914 die("Unsupported relocation type: %s (%d)\n", rel_type(r_type), r_type);
915 break;
916 }
917
918 return 0;
919 }
920
921 #endif
922
cmp_relocs(const void * va,const void * vb)923 static int cmp_relocs(const void *va, const void *vb)
924 {
925 const uint32_t *a, *b;
926
927 a = va;
928 b = vb;
929
930 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
931 }
932
sort_relocs(struct relocs * r)933 static void sort_relocs(struct relocs *r)
934 {
935 if (r->count)
936 qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
937 }
938
write32(uint32_t v,FILE * f)939 static int write32(uint32_t v, FILE *f)
940 {
941 unsigned char buf[4];
942
943 put_unaligned_le32(v, buf);
944
945 return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
946 }
947
write32_as_text(uint32_t v,FILE * f)948 static int write32_as_text(uint32_t v, FILE *f)
949 {
950 return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
951 }
952
emit_relocs(int as_text,int use_real_mode)953 static void emit_relocs(int as_text, int use_real_mode)
954 {
955 int i;
956 int (*write_reloc)(uint32_t, FILE *) = write32;
957 int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, const char *symname);
958
959 #if ELF_BITS == 64
960 if (!use_real_mode)
961 do_reloc = do_reloc64;
962 else
963 die("--realmode not valid for a 64-bit ELF file");
964 #else
965 if (!use_real_mode)
966 do_reloc = do_reloc32;
967 else
968 do_reloc = do_reloc_real;
969 #endif
970
971 /* Collect up the relocations */
972 walk_relocs(do_reloc);
973
974 if (relocs16.count && !use_real_mode)
975 die("Segment relocations found but --realmode not specified\n");
976
977 /* Order the relocations for more efficient processing */
978 sort_relocs(&relocs32);
979 #if ELF_BITS == 64
980 sort_relocs(&relocs64);
981 #else
982 sort_relocs(&relocs16);
983 #endif
984
985 /* Print the relocations */
986 if (as_text) {
987 /* Print the relocations in a form suitable that
988 * gas will like.
989 */
990 printf(".section \".data.reloc\",\"a\"\n");
991 printf(".balign 4\n");
992 write_reloc = write32_as_text;
993 }
994
995 if (use_real_mode) {
996 write_reloc(relocs16.count, stdout);
997 for (i = 0; i < relocs16.count; i++)
998 write_reloc(relocs16.offset[i], stdout);
999
1000 write_reloc(relocs32.count, stdout);
1001 for (i = 0; i < relocs32.count; i++)
1002 write_reloc(relocs32.offset[i], stdout);
1003 } else {
1004 #if ELF_BITS == 64
1005 /* Print a stop */
1006 write_reloc(0, stdout);
1007
1008 /* Now print each relocation */
1009 for (i = 0; i < relocs64.count; i++)
1010 write_reloc(relocs64.offset[i], stdout);
1011 #endif
1012
1013 /* Print a stop */
1014 write_reloc(0, stdout);
1015
1016 /* Now print each relocation */
1017 for (i = 0; i < relocs32.count; i++)
1018 write_reloc(relocs32.offset[i], stdout);
1019 }
1020 }
1021
1022 /*
1023 * As an aid to debugging problems with different linkers
1024 * print summary information about the relocs.
1025 * Since different linkers tend to emit the sections in
1026 * different orders we use the section names in the output.
1027 */
do_reloc_info(struct section * sec,Elf_Rel * rel,ElfW (Sym)* sym,const char * symname)1028 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1029 const char *symname)
1030 {
1031 printf("%s\t%s\t%s\t%s\n",
1032 sec_name(sec->shdr.sh_info),
1033 rel_type(ELF_R_TYPE(rel->r_info)),
1034 symname,
1035 sec_name(sym_index(sym)));
1036
1037 return 0;
1038 }
1039
print_reloc_info(void)1040 static void print_reloc_info(void)
1041 {
1042 printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1043 walk_relocs(do_reloc_info);
1044 }
1045
1046 #if ELF_BITS == 64
1047 # define process process_64
1048 #else
1049 # define process process_32
1050 #endif
1051
process(FILE * fp,int use_real_mode,int as_text,int show_absolute_syms,int show_absolute_relocs,int show_reloc_info)1052 void process(FILE *fp, int use_real_mode, int as_text,
1053 int show_absolute_syms, int show_absolute_relocs,
1054 int show_reloc_info)
1055 {
1056 regex_init(use_real_mode);
1057 read_ehdr(fp);
1058 read_shdrs(fp);
1059 read_strtabs(fp);
1060 read_symtabs(fp);
1061 read_relocs(fp);
1062
1063 if (show_absolute_syms) {
1064 print_absolute_symbols();
1065 return;
1066 }
1067
1068 if (show_absolute_relocs) {
1069 print_absolute_relocs();
1070 return;
1071 }
1072
1073 if (show_reloc_info) {
1074 print_reloc_info();
1075 return;
1076 }
1077
1078 emit_relocs(as_text, use_real_mode);
1079 }
1080