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Committer: Michael Beasley <mike@snafu.setup>
[mikesnafu-overlay.git] / arch / x86 / boot / compressed / relocs.c
blobd01ea42187e6aa8ddcd1218f229e74e6dda13148
1 #include <stdio.h>
2 #include <stdarg.h>
3 #include <stdlib.h>
4 #include <stdint.h>
5 #include <string.h>
6 #include <errno.h>
7 #include <unistd.h>
8 #include <elf.h>
9 #include <byteswap.h>
10 #define USE_BSD
11 #include <endian.h>
12
13 #define MAX_SHDRS 100
14 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
15 static Elf32_Ehdr ehdr;
16 static Elf32_Shdr shdr[MAX_SHDRS];
17 static Elf32_Sym *symtab[MAX_SHDRS];
18 static Elf32_Rel *reltab[MAX_SHDRS];
19 static char *strtab[MAX_SHDRS];
20 static unsigned long reloc_count, reloc_idx;
21 static unsigned long *relocs;
22
23 /*
24 * Following symbols have been audited. There values are constant and do
25 * not change if bzImage is loaded at a different physical address than
26 * the address for which it has been compiled. Don't warn user about
27 * absolute relocations present w.r.t these symbols.
28 */
29 static const char* safe_abs_relocs[] = {
30 "xen_irq_disable_direct_reloc",
31 "xen_save_fl_direct_reloc",
32 };
33
34 static int is_safe_abs_reloc(const char* sym_name)
35 {
36 int i;
37
38 for(i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
39 if (!strcmp(sym_name, safe_abs_relocs[i]))
40 /* Match found */
41 return 1;
42 }
43 if (strncmp(sym_name, "VDSO", 4) == 0)
44 return 1;
45 if (strncmp(sym_name, "__crc_", 6) == 0)
46 return 1;
47 return 0;
48 }
49
50 static void die(char *fmt, ...)
51 {
52 va_list ap;
53 va_start(ap, fmt);
54 vfprintf(stderr, fmt, ap);
55 va_end(ap);
56 exit(1);
57 }
58
59 static const char *sym_type(unsigned type)
60 {
61 static const char *type_name[] = {
62 #define SYM_TYPE(X) [X] = #X
63 SYM_TYPE(STT_NOTYPE),
64 SYM_TYPE(STT_OBJECT),
65 SYM_TYPE(STT_FUNC),
66 SYM_TYPE(STT_SECTION),
67 SYM_TYPE(STT_FILE),
68 SYM_TYPE(STT_COMMON),
69 SYM_TYPE(STT_TLS),
70 #undef SYM_TYPE
71 };
72 const char *name = "unknown sym type name";
73 if (type < ARRAY_SIZE(type_name)) {
74 name = type_name[type];
75 }
76 return name;
77 }
78
79 static const char *sym_bind(unsigned bind)
80 {
81 static const char *bind_name[] = {
82 #define SYM_BIND(X) [X] = #X
83 SYM_BIND(STB_LOCAL),
84 SYM_BIND(STB_GLOBAL),
85 SYM_BIND(STB_WEAK),
86 #undef SYM_BIND
87 };
88 const char *name = "unknown sym bind name";
89 if (bind < ARRAY_SIZE(bind_name)) {
90 name = bind_name[bind];
91 }
92 return name;
93 }
94
95 static const char *sym_visibility(unsigned visibility)
96 {
97 static const char *visibility_name[] = {
98 #define SYM_VISIBILITY(X) [X] = #X
99 SYM_VISIBILITY(STV_DEFAULT),
100 SYM_VISIBILITY(STV_INTERNAL),
101 SYM_VISIBILITY(STV_HIDDEN),
102 SYM_VISIBILITY(STV_PROTECTED),
103 #undef SYM_VISIBILITY
104 };
105 const char *name = "unknown sym visibility name";
106 if (visibility < ARRAY_SIZE(visibility_name)) {
107 name = visibility_name[visibility];
108 }
109 return name;
110 }
111
112 static const char *rel_type(unsigned type)
113 {
114 static const char *type_name[] = {
115 #define REL_TYPE(X) [X] = #X
116 REL_TYPE(R_386_NONE),
117 REL_TYPE(R_386_32),
118 REL_TYPE(R_386_PC32),
119 REL_TYPE(R_386_GOT32),
120 REL_TYPE(R_386_PLT32),
121 REL_TYPE(R_386_COPY),
122 REL_TYPE(R_386_GLOB_DAT),
123 REL_TYPE(R_386_JMP_SLOT),
124 REL_TYPE(R_386_RELATIVE),
125 REL_TYPE(R_386_GOTOFF),
126 REL_TYPE(R_386_GOTPC),
127 #undef REL_TYPE
128 };
129 const char *name = "unknown type rel type name";
130 if (type < ARRAY_SIZE(type_name)) {
131 name = type_name[type];
132 }
133 return name;
134 }
135
136 static const char *sec_name(unsigned shndx)
137 {
138 const char *sec_strtab;
139 const char *name;
140 sec_strtab = strtab[ehdr.e_shstrndx];
141 name = "<noname>";
142 if (shndx < ehdr.e_shnum) {
143 name = sec_strtab + shdr[shndx].sh_name;
144 }
145 else if (shndx == SHN_ABS) {
146 name = "ABSOLUTE";
147 }
148 else if (shndx == SHN_COMMON) {
149 name = "COMMON";
150 }
151 return name;
152 }
153
154 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
155 {
156 const char *name;
157 name = "<noname>";
158 if (sym->st_name) {
159 name = sym_strtab + sym->st_name;
160 }
161 else {
162 name = sec_name(shdr[sym->st_shndx].sh_name);
163 }
164 return name;
165 }
166
167
168
169 #if BYTE_ORDER == LITTLE_ENDIAN
170 #define le16_to_cpu(val) (val)
171 #define le32_to_cpu(val) (val)
172 #endif
173 #if BYTE_ORDER == BIG_ENDIAN
174 #define le16_to_cpu(val) bswap_16(val)
175 #define le32_to_cpu(val) bswap_32(val)
176 #endif
177
178 static uint16_t elf16_to_cpu(uint16_t val)
179 {
180 return le16_to_cpu(val);
181 }
182
183 static uint32_t elf32_to_cpu(uint32_t val)
184 {
185 return le32_to_cpu(val);
186 }
187
188 static void read_ehdr(FILE *fp)
189 {
190 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
191 die("Cannot read ELF header: %s\n",
192 strerror(errno));
193 }
194 if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
195 die("No ELF magic\n");
196 }
197 if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
198 die("Not a 32 bit executable\n");
199 }
200 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
201 die("Not a LSB ELF executable\n");
202 }
203 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
204 die("Unknown ELF version\n");
205 }
206 /* Convert the fields to native endian */
207 ehdr.e_type = elf16_to_cpu(ehdr.e_type);
208 ehdr.e_machine = elf16_to_cpu(ehdr.e_machine);
209 ehdr.e_version = elf32_to_cpu(ehdr.e_version);
210 ehdr.e_entry = elf32_to_cpu(ehdr.e_entry);
211 ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff);
212 ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff);
213 ehdr.e_flags = elf32_to_cpu(ehdr.e_flags);
214 ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize);
215 ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
216 ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum);
217 ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
218 ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum);
219 ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx);
220
221 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
222 die("Unsupported ELF header type\n");
223 }
224 if (ehdr.e_machine != EM_386) {
225 die("Not for x86\n");
226 }
227 if (ehdr.e_version != EV_CURRENT) {
228 die("Unknown ELF version\n");
229 }
230 if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
231 die("Bad Elf header size\n");
232 }
233 if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
234 die("Bad program header entry\n");
235 }
236 if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
237 die("Bad section header entry\n");
238 }
239 if (ehdr.e_shstrndx >= ehdr.e_shnum) {
240 die("String table index out of bounds\n");
241 }
242 }
243
244 static void read_shdrs(FILE *fp)
245 {
246 int i;
247 if (ehdr.e_shnum > MAX_SHDRS) {
248 die("%d section headers supported: %d\n",
249 ehdr.e_shnum, MAX_SHDRS);
250 }
251 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
252 die("Seek to %d failed: %s\n",
253 ehdr.e_shoff, strerror(errno));
254 }
255 if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
256 die("Cannot read ELF section headers: %s\n",
257 strerror(errno));
258 }
259 for(i = 0; i < ehdr.e_shnum; i++) {
260 shdr[i].sh_name = elf32_to_cpu(shdr[i].sh_name);
261 shdr[i].sh_type = elf32_to_cpu(shdr[i].sh_type);
262 shdr[i].sh_flags = elf32_to_cpu(shdr[i].sh_flags);
263 shdr[i].sh_addr = elf32_to_cpu(shdr[i].sh_addr);
264 shdr[i].sh_offset = elf32_to_cpu(shdr[i].sh_offset);
265 shdr[i].sh_size = elf32_to_cpu(shdr[i].sh_size);
266 shdr[i].sh_link = elf32_to_cpu(shdr[i].sh_link);
267 shdr[i].sh_info = elf32_to_cpu(shdr[i].sh_info);
268 shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
269 shdr[i].sh_entsize = elf32_to_cpu(shdr[i].sh_entsize);
270 }
271
272 }
273
274 static void read_strtabs(FILE *fp)
275 {
276 int i;
277 for(i = 0; i < ehdr.e_shnum; i++) {
278 if (shdr[i].sh_type != SHT_STRTAB) {
279 continue;
280 }
281 strtab[i] = malloc(shdr[i].sh_size);
282 if (!strtab[i]) {
283 die("malloc of %d bytes for strtab failed\n",
284 shdr[i].sh_size);
285 }
286 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
287 die("Seek to %d failed: %s\n",
288 shdr[i].sh_offset, strerror(errno));
289 }
290 if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
291 die("Cannot read symbol table: %s\n",
292 strerror(errno));
293 }
294 }
295 }
296
297 static void read_symtabs(FILE *fp)
298 {
299 int i,j;
300 for(i = 0; i < ehdr.e_shnum; i++) {
301 if (shdr[i].sh_type != SHT_SYMTAB) {
302 continue;
303 }
304 symtab[i] = malloc(shdr[i].sh_size);
305 if (!symtab[i]) {
306 die("malloc of %d bytes for symtab failed\n",
307 shdr[i].sh_size);
308 }
309 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
310 die("Seek to %d failed: %s\n",
311 shdr[i].sh_offset, strerror(errno));
312 }
313 if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
314 die("Cannot read symbol table: %s\n",
315 strerror(errno));
316 }
317 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
318 symtab[i][j].st_name = elf32_to_cpu(symtab[i][j].st_name);
319 symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
320 symtab[i][j].st_size = elf32_to_cpu(symtab[i][j].st_size);
321 symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
322 }
323 }
324 }
325
326
327 static void read_relocs(FILE *fp)
328 {
329 int i,j;
330 for(i = 0; i < ehdr.e_shnum; i++) {
331 if (shdr[i].sh_type != SHT_REL) {
332 continue;
333 }
334 reltab[i] = malloc(shdr[i].sh_size);
335 if (!reltab[i]) {
336 die("malloc of %d bytes for relocs failed\n",
337 shdr[i].sh_size);
338 }
339 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
340 die("Seek to %d failed: %s\n",
341 shdr[i].sh_offset, strerror(errno));
342 }
343 if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
344 die("Cannot read symbol table: %s\n",
345 strerror(errno));
346 }
347 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
348 reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
349 reltab[i][j].r_info = elf32_to_cpu(reltab[i][j].r_info);
350 }
351 }
352 }
353
354
355 static void print_absolute_symbols(void)
356 {
357 int i;
358 printf("Absolute symbols\n");
359 printf(" Num: Value Size Type Bind Visibility Name\n");
360 for(i = 0; i < ehdr.e_shnum; i++) {
361 char *sym_strtab;
362 Elf32_Sym *sh_symtab;
363 int j;
364 if (shdr[i].sh_type != SHT_SYMTAB) {
365 continue;
366 }
367 sh_symtab = symtab[i];
368 sym_strtab = strtab[shdr[i].sh_link];
369 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
370 Elf32_Sym *sym;
371 const char *name;
372 sym = &symtab[i][j];
373 name = sym_name(sym_strtab, sym);
374 if (sym->st_shndx != SHN_ABS) {
375 continue;
376 }
377 printf("%5d %08x %5d %10s %10s %12s %s\n",
378 j, sym->st_value, sym->st_size,
379 sym_type(ELF32_ST_TYPE(sym->st_info)),
380 sym_bind(ELF32_ST_BIND(sym->st_info)),
381 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
382 name);
383 }
384 }
385 printf("\n");
386 }
387
388 static void print_absolute_relocs(void)
389 {
390 int i, printed = 0;
391
392 for(i = 0; i < ehdr.e_shnum; i++) {
393 char *sym_strtab;
394 Elf32_Sym *sh_symtab;
395 unsigned sec_applies, sec_symtab;
396 int j;
397 if (shdr[i].sh_type != SHT_REL) {
398 continue;
399 }
400 sec_symtab = shdr[i].sh_link;
401 sec_applies = shdr[i].sh_info;
402 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
403 continue;
404 }
405 sh_symtab = symtab[sec_symtab];
406 sym_strtab = strtab[shdr[sec_symtab].sh_link];
407 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
408 Elf32_Rel *rel;
409 Elf32_Sym *sym;
410 const char *name;
411 rel = &reltab[i][j];
412 sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
413 name = sym_name(sym_strtab, sym);
414 if (sym->st_shndx != SHN_ABS) {
415 continue;
416 }
417
418 /* Absolute symbols are not relocated if bzImage is
419 * loaded at a non-compiled address. Display a warning
420 * to user at compile time about the absolute
421 * relocations present.
422 *
423 * User need to audit the code to make sure
424 * some symbols which should have been section
425 * relative have not become absolute because of some
426 * linker optimization or wrong programming usage.
427 *
428 * Before warning check if this absolute symbol
429 * relocation is harmless.
430 */
431 if (is_safe_abs_reloc(name))
432 continue;
433
434 if (!printed) {
435 printf("WARNING: Absolute relocations"
436 " present\n");
437 printf("Offset Info Type Sym.Value "
438 "Sym.Name\n");
439 printed = 1;
440 }
441
442 printf("%08x %08x %10s %08x %s\n",
443 rel->r_offset,
444 rel->r_info,
445 rel_type(ELF32_R_TYPE(rel->r_info)),
446 sym->st_value,
447 name);
448 }
449 }
450
451 if (printed)
452 printf("\n");
453 }
454
455 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
456 {
457 int i;
458 /* Walk through the relocations */
459 for(i = 0; i < ehdr.e_shnum; i++) {
460 char *sym_strtab;
461 Elf32_Sym *sh_symtab;
462 unsigned sec_applies, sec_symtab;
463 int j;
464 if (shdr[i].sh_type != SHT_REL) {
465 continue;
466 }
467 sec_symtab = shdr[i].sh_link;
468 sec_applies = shdr[i].sh_info;
469 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
470 continue;
471 }
472 sh_symtab = symtab[sec_symtab];
473 sym_strtab = strtab[shdr[sec_symtab].sh_link];
474 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
475 Elf32_Rel *rel;
476 Elf32_Sym *sym;
477 unsigned r_type;
478 rel = &reltab[i][j];
479 sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
480 r_type = ELF32_R_TYPE(rel->r_info);
481 /* Don't visit relocations to absolute symbols */
482 if (sym->st_shndx == SHN_ABS) {
483 continue;
484 }
485 if (r_type == R_386_PC32) {
486 /* PC relative relocations don't need to be adjusted */
487 }
488 else if (r_type == R_386_32) {
489 /* Visit relocations that need to be adjusted */
490 visit(rel, sym);
491 }
492 else {
493 die("Unsupported relocation type: %d\n", r_type);
494 }
495 }
496 }
497 }
498
499 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
500 {
501 reloc_count += 1;
502 }
503
504 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
505 {
506 /* Remember the address that needs to be adjusted. */
507 relocs[reloc_idx++] = rel->r_offset;
508 }
509
510 static int cmp_relocs(const void *va, const void *vb)
511 {
512 const unsigned long *a, *b;
513 a = va; b = vb;
514 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
515 }
516
517 static void emit_relocs(int as_text)
518 {
519 int i;
520 /* Count how many relocations I have and allocate space for them. */
521 reloc_count = 0;
522 walk_relocs(count_reloc);
523 relocs = malloc(reloc_count * sizeof(relocs[0]));
524 if (!relocs) {
525 die("malloc of %d entries for relocs failed\n",
526 reloc_count);
527 }
528 /* Collect up the relocations */
529 reloc_idx = 0;
530 walk_relocs(collect_reloc);
531
532 /* Order the relocations for more efficient processing */
533 qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
534
535 /* Print the relocations */
536 if (as_text) {
537 /* Print the relocations in a form suitable that
538 * gas will like.
539 */
540 printf(".section \".data.reloc\",\"a\"\n");
541 printf(".balign 4\n");
542 for(i = 0; i < reloc_count; i++) {
543 printf("\t .long 0x%08lx\n", relocs[i]);
544 }
545 printf("\n");
546 }
547 else {
548 unsigned char buf[4];
549 buf[0] = buf[1] = buf[2] = buf[3] = 0;
550 /* Print a stop */
551 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
552 /* Now print each relocation */
553 for(i = 0; i < reloc_count; i++) {
554 buf[0] = (relocs[i] >> 0) & 0xff;
555 buf[1] = (relocs[i] >> 8) & 0xff;
556 buf[2] = (relocs[i] >> 16) & 0xff;
557 buf[3] = (relocs[i] >> 24) & 0xff;
558 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
559 }
560 }
561 }
562
563 static void usage(void)
564 {
565 die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
566 }
567
568 int main(int argc, char **argv)
569 {
570 int show_absolute_syms, show_absolute_relocs;
571 int as_text;
572 const char *fname;
573 FILE *fp;
574 int i;
575
576 show_absolute_syms = 0;
577 show_absolute_relocs = 0;
578 as_text = 0;
579 fname = NULL;
580 for(i = 1; i < argc; i++) {
581 char *arg = argv[i];
582 if (*arg == '-') {
583 if (strcmp(argv[1], "--abs-syms") == 0) {
584 show_absolute_syms = 1;
585 continue;
586 }
587
588 if (strcmp(argv[1], "--abs-relocs") == 0) {
589 show_absolute_relocs = 1;
590 continue;
591 }
592 else if (strcmp(argv[1], "--text") == 0) {
593 as_text = 1;
594 continue;
595 }
596 }
597 else if (!fname) {
598 fname = arg;
599 continue;
600 }
601 usage();
602 }
603 if (!fname) {
604 usage();
605 }
606 fp = fopen(fname, "r");
607 if (!fp) {
608 die("Cannot open %s: %s\n",
609 fname, strerror(errno));
610 }
611 read_ehdr(fp);
612 read_shdrs(fp);
613 read_strtabs(fp);
614 read_symtabs(fp);
615 read_relocs(fp);
616 if (show_absolute_syms) {
617 print_absolute_symbols();
618 return 0;
619 }
620 if (show_absolute_relocs) {
621 print_absolute_relocs();
622 return 0;
623 }
624 emit_relocs(as_text);
625 return 0;
626 }
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