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-rw-r--r--arch/i386/boot/compressed/relocs.c625
1 files changed, 625 insertions, 0 deletions
diff --git a/arch/i386/boot/compressed/relocs.c b/arch/i386/boot/compressed/relocs.c
new file mode 100644
index 000000000000..468da89153c4
--- /dev/null
+++ b/arch/i386/boot/compressed/relocs.c
@@ -0,0 +1,625 @@
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
14static Elf32_Ehdr ehdr;
15static Elf32_Shdr shdr[MAX_SHDRS];
16static Elf32_Sym *symtab[MAX_SHDRS];
17static Elf32_Rel *reltab[MAX_SHDRS];
18static char *strtab[MAX_SHDRS];
19static unsigned long reloc_count, reloc_idx;
20static unsigned long *relocs;
21
22/*
23 * Following symbols have been audited. There values are constant and do
24 * not change if bzImage is loaded at a different physical address than
25 * the address for which it has been compiled. Don't warn user about
26 * absolute relocations present w.r.t these symbols.
27 */
28static const char* safe_abs_relocs[] = {
29 "__kernel_vsyscall",
30 "__kernel_rt_sigreturn",
31 "__kernel_sigreturn",
32 "SYSENTER_RETURN",
33};
34
35static int is_safe_abs_reloc(const char* sym_name)
36{
37 int i, array_size;
38
39 array_size = sizeof(safe_abs_relocs)/sizeof(char*);
40
41 for(i = 0; i < array_size; i++) {
42 if (!strcmp(sym_name, safe_abs_relocs[i]))
43 /* Match found */
44 return 1;
45 }
46 return 0;
47}
48
49static void die(char *fmt, ...)
50{
51 va_list ap;
52 va_start(ap, fmt);
53 vfprintf(stderr, fmt, ap);
54 va_end(ap);
55 exit(1);
56}
57
58static const char *sym_type(unsigned type)
59{
60 static const char *type_name[] = {
61#define SYM_TYPE(X) [X] = #X
62 SYM_TYPE(STT_NOTYPE),
63 SYM_TYPE(STT_OBJECT),
64 SYM_TYPE(STT_FUNC),
65 SYM_TYPE(STT_SECTION),
66 SYM_TYPE(STT_FILE),
67 SYM_TYPE(STT_COMMON),
68 SYM_TYPE(STT_TLS),
69#undef SYM_TYPE
70 };
71 const char *name = "unknown sym type name";
72 if (type < sizeof(type_name)/sizeof(type_name[0])) {
73 name = type_name[type];
74 }
75 return name;
76}
77
78static const char *sym_bind(unsigned bind)
79{
80 static const char *bind_name[] = {
81#define SYM_BIND(X) [X] = #X
82 SYM_BIND(STB_LOCAL),
83 SYM_BIND(STB_GLOBAL),
84 SYM_BIND(STB_WEAK),
85#undef SYM_BIND
86 };
87 const char *name = "unknown sym bind name";
88 if (bind < sizeof(bind_name)/sizeof(bind_name[0])) {
89 name = bind_name[bind];
90 }
91 return name;
92}
93
94static const char *sym_visibility(unsigned visibility)
95{
96 static const char *visibility_name[] = {
97#define SYM_VISIBILITY(X) [X] = #X
98 SYM_VISIBILITY(STV_DEFAULT),
99 SYM_VISIBILITY(STV_INTERNAL),
100 SYM_VISIBILITY(STV_HIDDEN),
101 SYM_VISIBILITY(STV_PROTECTED),
102#undef SYM_VISIBILITY
103 };
104 const char *name = "unknown sym visibility name";
105 if (visibility < sizeof(visibility_name)/sizeof(visibility_name[0])) {
106 name = visibility_name[visibility];
107 }
108 return name;
109}
110
111static const char *rel_type(unsigned type)
112{
113 static const char *type_name[] = {
114#define REL_TYPE(X) [X] = #X
115 REL_TYPE(R_386_NONE),
116 REL_TYPE(R_386_32),
117 REL_TYPE(R_386_PC32),
118 REL_TYPE(R_386_GOT32),
119 REL_TYPE(R_386_PLT32),
120 REL_TYPE(R_386_COPY),
121 REL_TYPE(R_386_GLOB_DAT),
122 REL_TYPE(R_386_JMP_SLOT),
123 REL_TYPE(R_386_RELATIVE),
124 REL_TYPE(R_386_GOTOFF),
125 REL_TYPE(R_386_GOTPC),
126#undef REL_TYPE
127 };
128 const char *name = "unknown type rel type name";
129 if (type < sizeof(type_name)/sizeof(type_name[0])) {
130 name = type_name[type];
131 }
132 return name;
133}
134
135static const char *sec_name(unsigned shndx)
136{
137 const char *sec_strtab;
138 const char *name;
139 sec_strtab = strtab[ehdr.e_shstrndx];
140 name = "<noname>";
141 if (shndx < ehdr.e_shnum) {
142 name = sec_strtab + shdr[shndx].sh_name;
143 }
144 else if (shndx == SHN_ABS) {
145 name = "ABSOLUTE";
146 }
147 else if (shndx == SHN_COMMON) {
148 name = "COMMON";
149 }
150 return name;
151}
152
153static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
154{
155 const char *name;
156 name = "<noname>";
157 if (sym->st_name) {
158 name = sym_strtab + sym->st_name;
159 }
160 else {
161 name = sec_name(shdr[sym->st_shndx].sh_name);
162 }
163 return name;
164}
165
166
167
168#if BYTE_ORDER == LITTLE_ENDIAN
169#define le16_to_cpu(val) (val)
170#define le32_to_cpu(val) (val)
171#endif
172#if BYTE_ORDER == BIG_ENDIAN
173#define le16_to_cpu(val) bswap_16(val)
174#define le32_to_cpu(val) bswap_32(val)
175#endif
176
177static uint16_t elf16_to_cpu(uint16_t val)
178{
179 return le16_to_cpu(val);
180}
181
182static uint32_t elf32_to_cpu(uint32_t val)
183{
184 return le32_to_cpu(val);
185}
186
187static void read_ehdr(FILE *fp)
188{
189 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
190 die("Cannot read ELF header: %s\n",
191 strerror(errno));
192 }
193 if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
194 die("No ELF magic\n");
195 }
196 if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
197 die("Not a 32 bit executable\n");
198 }
199 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
200 die("Not a LSB ELF executable\n");
201 }
202 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
203 die("Unknown ELF version\n");
204 }
205 /* Convert the fields to native endian */
206 ehdr.e_type = elf16_to_cpu(ehdr.e_type);
207 ehdr.e_machine = elf16_to_cpu(ehdr.e_machine);
208 ehdr.e_version = elf32_to_cpu(ehdr.e_version);
209 ehdr.e_entry = elf32_to_cpu(ehdr.e_entry);
210 ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff);
211 ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff);
212 ehdr.e_flags = elf32_to_cpu(ehdr.e_flags);
213 ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize);
214 ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
215 ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum);
216 ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
217 ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum);
218 ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx);
219
220 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
221 die("Unsupported ELF header type\n");
222 }
223 if (ehdr.e_machine != EM_386) {
224 die("Not for x86\n");
225 }
226 if (ehdr.e_version != EV_CURRENT) {
227 die("Unknown ELF version\n");
228 }
229 if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
230 die("Bad Elf header size\n");
231 }
232 if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
233 die("Bad program header entry\n");
234 }
235 if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
236 die("Bad section header entry\n");
237 }
238 if (ehdr.e_shstrndx >= ehdr.e_shnum) {
239 die("String table index out of bounds\n");
240 }
241}
242
243static void read_shdrs(FILE *fp)
244{
245 int i;
246 if (ehdr.e_shnum > MAX_SHDRS) {
247 die("%d section headers supported: %d\n",
248 ehdr.e_shnum, MAX_SHDRS);
249 }
250 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
251 die("Seek to %d failed: %s\n",
252 ehdr.e_shoff, strerror(errno));
253 }
254 if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
255 die("Cannot read ELF section headers: %s\n",
256 strerror(errno));
257 }
258 for(i = 0; i < ehdr.e_shnum; i++) {
259 shdr[i].sh_name = elf32_to_cpu(shdr[i].sh_name);
260 shdr[i].sh_type = elf32_to_cpu(shdr[i].sh_type);
261 shdr[i].sh_flags = elf32_to_cpu(shdr[i].sh_flags);
262 shdr[i].sh_addr = elf32_to_cpu(shdr[i].sh_addr);
263 shdr[i].sh_offset = elf32_to_cpu(shdr[i].sh_offset);
264 shdr[i].sh_size = elf32_to_cpu(shdr[i].sh_size);
265 shdr[i].sh_link = elf32_to_cpu(shdr[i].sh_link);
266 shdr[i].sh_info = elf32_to_cpu(shdr[i].sh_info);
267 shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
268 shdr[i].sh_entsize = elf32_to_cpu(shdr[i].sh_entsize);
269 }
270
271}
272
273static void read_strtabs(FILE *fp)
274{
275 int i;
276 for(i = 0; i < ehdr.e_shnum; i++) {
277 if (shdr[i].sh_type != SHT_STRTAB) {
278 continue;
279 }
280 strtab[i] = malloc(shdr[i].sh_size);
281 if (!strtab[i]) {
282 die("malloc of %d bytes for strtab failed\n",
283 shdr[i].sh_size);
284 }
285 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
286 die("Seek to %d failed: %s\n",
287 shdr[i].sh_offset, strerror(errno));
288 }
289 if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
290 die("Cannot read symbol table: %s\n",
291 strerror(errno));
292 }
293 }
294}
295
296static void read_symtabs(FILE *fp)
297{
298 int i,j;
299 for(i = 0; i < ehdr.e_shnum; i++) {
300 if (shdr[i].sh_type != SHT_SYMTAB) {
301 continue;
302 }
303 symtab[i] = malloc(shdr[i].sh_size);
304 if (!symtab[i]) {
305 die("malloc of %d bytes for symtab failed\n",
306 shdr[i].sh_size);
307 }
308 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
309 die("Seek to %d failed: %s\n",
310 shdr[i].sh_offset, strerror(errno));
311 }
312 if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
313 die("Cannot read symbol table: %s\n",
314 strerror(errno));
315 }
316 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
317 symtab[i][j].st_name = elf32_to_cpu(symtab[i][j].st_name);
318 symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
319 symtab[i][j].st_size = elf32_to_cpu(symtab[i][j].st_size);
320 symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
321 }
322 }
323}
324
325
326static void read_relocs(FILE *fp)
327{
328 int i,j;
329 for(i = 0; i < ehdr.e_shnum; i++) {
330 if (shdr[i].sh_type != SHT_REL) {
331 continue;
332 }
333 reltab[i] = malloc(shdr[i].sh_size);
334 if (!reltab[i]) {
335 die("malloc of %d bytes for relocs failed\n",
336 shdr[i].sh_size);
337 }
338 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
339 die("Seek to %d failed: %s\n",
340 shdr[i].sh_offset, strerror(errno));
341 }
342 if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
343 die("Cannot read symbol table: %s\n",
344 strerror(errno));
345 }
346 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
347 reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
348 reltab[i][j].r_info = elf32_to_cpu(reltab[i][j].r_info);
349 }
350 }
351}
352
353
354static void print_absolute_symbols(void)
355{
356 int i;
357 printf("Absolute symbols\n");
358 printf(" Num: Value Size Type Bind Visibility Name\n");
359 for(i = 0; i < ehdr.e_shnum; i++) {
360 char *sym_strtab;
361 Elf32_Sym *sh_symtab;
362 int j;
363 if (shdr[i].sh_type != SHT_SYMTAB) {
364 continue;
365 }
366 sh_symtab = symtab[i];
367 sym_strtab = strtab[shdr[i].sh_link];
368 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
369 Elf32_Sym *sym;
370 const char *name;
371 sym = &symtab[i][j];
372 name = sym_name(sym_strtab, sym);
373 if (sym->st_shndx != SHN_ABS) {
374 continue;
375 }
376 printf("%5d %08x %5d %10s %10s %12s %s\n",
377 j, sym->st_value, sym->st_size,
378 sym_type(ELF32_ST_TYPE(sym->st_info)),
379 sym_bind(ELF32_ST_BIND(sym->st_info)),
380 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
381 name);
382 }
383 }
384 printf("\n");
385}
386
387static void print_absolute_relocs(void)
388{
389 int i, printed = 0;
390
391 for(i = 0; i < ehdr.e_shnum; i++) {
392 char *sym_strtab;
393 Elf32_Sym *sh_symtab;
394 unsigned sec_applies, sec_symtab;
395 int j;
396 if (shdr[i].sh_type != SHT_REL) {
397 continue;
398 }
399 sec_symtab = shdr[i].sh_link;
400 sec_applies = shdr[i].sh_info;
401 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
402 continue;
403 }
404 sh_symtab = symtab[sec_symtab];
405 sym_strtab = strtab[shdr[sec_symtab].sh_link];
406 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
407 Elf32_Rel *rel;
408 Elf32_Sym *sym;
409 const char *name;
410 rel = &reltab[i][j];
411 sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
412 name = sym_name(sym_strtab, sym);
413 if (sym->st_shndx != SHN_ABS) {
414 continue;
415 }
416
417 /* Absolute symbols are not relocated if bzImage is
418 * loaded at a non-compiled address. Display a warning
419 * to user at compile time about the absolute
420 * relocations present.
421 *
422 * User need to audit the code to make sure
423 * some symbols which should have been section
424 * relative have not become absolute because of some
425 * linker optimization or wrong programming usage.
426 *
427 * Before warning check if this absolute symbol
428 * relocation is harmless.
429 */
430 if (is_safe_abs_reloc(name))
431 continue;
432
433 if (!printed) {
434 printf("WARNING: Absolute relocations"
435 " present\n");
436 printf("Offset Info Type Sym.Value "
437 "Sym.Name\n");
438 printed = 1;
439 }
440
441 printf("%08x %08x %10s %08x %s\n",
442 rel->r_offset,
443 rel->r_info,
444 rel_type(ELF32_R_TYPE(rel->r_info)),
445 sym->st_value,
446 name);
447 }
448 }
449
450 if (printed)
451 printf("\n");
452}
453
454static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
455{
456 int i;
457 /* Walk through the relocations */
458 for(i = 0; i < ehdr.e_shnum; i++) {
459 char *sym_strtab;
460 Elf32_Sym *sh_symtab;
461 unsigned sec_applies, sec_symtab;
462 int j;
463 if (shdr[i].sh_type != SHT_REL) {
464 continue;
465 }
466 sec_symtab = shdr[i].sh_link;
467 sec_applies = shdr[i].sh_info;
468 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
469 continue;
470 }
471 sh_symtab = symtab[sec_symtab];
472 sym_strtab = strtab[shdr[sec_symtab].sh_link];
473 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
474 Elf32_Rel *rel;
475 Elf32_Sym *sym;
476 unsigned r_type;
477 rel = &reltab[i][j];
478 sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
479 r_type = ELF32_R_TYPE(rel->r_info);
480 /* Don't visit relocations to absolute symbols */
481 if (sym->st_shndx == SHN_ABS) {
482 continue;
483 }
484 if (r_type == R_386_PC32) {
485 /* PC relative relocations don't need to be adjusted */
486 }
487 else if (r_type == R_386_32) {
488 /* Visit relocations that need to be adjusted */
489 visit(rel, sym);
490 }
491 else {
492 die("Unsupported relocation type: %d\n", r_type);
493 }
494 }
495 }
496}
497
498static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
499{
500 reloc_count += 1;
501}
502
503static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
504{
505 /* Remember the address that needs to be adjusted. */
506 relocs[reloc_idx++] = rel->r_offset;
507}
508
509static int cmp_relocs(const void *va, const void *vb)
510{
511 const unsigned long *a, *b;
512 a = va; b = vb;
513 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
514}
515
516static void emit_relocs(int as_text)
517{
518 int i;
519 /* Count how many relocations I have and allocate space for them. */
520 reloc_count = 0;
521 walk_relocs(count_reloc);
522 relocs = malloc(reloc_count * sizeof(relocs[0]));
523 if (!relocs) {
524 die("malloc of %d entries for relocs failed\n",
525 reloc_count);
526 }
527 /* Collect up the relocations */
528 reloc_idx = 0;
529 walk_relocs(collect_reloc);
530
531 /* Order the relocations for more efficient processing */
532 qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
533
534 /* Print the relocations */
535 if (as_text) {
536 /* Print the relocations in a form suitable that
537 * gas will like.
538 */
539 printf(".section \".data.reloc\",\"a\"\n");
540 printf(".balign 4\n");
541 for(i = 0; i < reloc_count; i++) {
542 printf("\t .long 0x%08lx\n", relocs[i]);
543 }
544 printf("\n");
545 }
546 else {
547 unsigned char buf[4];
548 buf[0] = buf[1] = buf[2] = buf[3] = 0;
549 /* Print a stop */
550 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
551 /* Now print each relocation */
552 for(i = 0; i < reloc_count; i++) {
553 buf[0] = (relocs[i] >> 0) & 0xff;
554 buf[1] = (relocs[i] >> 8) & 0xff;
555 buf[2] = (relocs[i] >> 16) & 0xff;
556 buf[3] = (relocs[i] >> 24) & 0xff;
557 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
558 }
559 }
560}
561
562static void usage(void)
563{
564 die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
565}
566
567int main(int argc, char **argv)
568{
569 int show_absolute_syms, show_absolute_relocs;
570 int as_text;
571 const char *fname;
572 FILE *fp;
573 int i;
574
575 show_absolute_syms = 0;
576 show_absolute_relocs = 0;
577 as_text = 0;
578 fname = NULL;
579 for(i = 1; i < argc; i++) {
580 char *arg = argv[i];
581 if (*arg == '-') {
582 if (strcmp(argv[1], "--abs-syms") == 0) {
583 show_absolute_syms = 1;
584 continue;
585 }
586
587 if (strcmp(argv[1], "--abs-relocs") == 0) {
588 show_absolute_relocs = 1;
589 continue;
590 }
591 else if (strcmp(argv[1], "--text") == 0) {
592 as_text = 1;
593 continue;
594 }
595 }
596 else if (!fname) {
597 fname = arg;
598 continue;
599 }
600 usage();
601 }
602 if (!fname) {
603 usage();
604 }
605 fp = fopen(fname, "r");
606 if (!fp) {
607 die("Cannot open %s: %s\n",
608 fname, strerror(errno));
609 }
610 read_ehdr(fp);
611 read_shdrs(fp);
612 read_strtabs(fp);
613 read_symtabs(fp);
614 read_relocs(fp);
615 if (show_absolute_syms) {
616 print_absolute_symbols();
617 return 0;
618 }
619 if (show_absolute_relocs) {
620 print_absolute_relocs();
621 return 0;
622 }
623 emit_relocs(as_text);
624 return 0;
625}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-15 01:33:02 -0500