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;
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.
29 static const char* safe_abs_relocs[] = {
31 "__kernel_rt_sigreturn",
36 static int is_safe_abs_reloc(const char* sym_name)
40 array_size = sizeof(safe_abs_relocs)/sizeof(char*);
42 for(i = 0; i < array_size; i++) {
43 if (!strcmp(sym_name, safe_abs_relocs[i]))
47 if (strncmp(sym_name, "__crc_", 6) == 0)
52 static void die(char *fmt, ...)
56 vfprintf(stderr, fmt, ap);
61 static const char *sym_type(unsigned type)
63 static const char *type_name[] = {
64 #define SYM_TYPE(X) [X] = #X
68 SYM_TYPE(STT_SECTION),
74 const char *name = "unknown sym type name";
75 if (type < ARRAY_SIZE(type_name)) {
76 name = type_name[type];
81 static const char *sym_bind(unsigned bind)
83 static const char *bind_name[] = {
84 #define SYM_BIND(X) [X] = #X
90 const char *name = "unknown sym bind name";
91 if (bind < ARRAY_SIZE(bind_name)) {
92 name = bind_name[bind];
97 static const char *sym_visibility(unsigned visibility)
99 static const char *visibility_name[] = {
100 #define SYM_VISIBILITY(X) [X] = #X
101 SYM_VISIBILITY(STV_DEFAULT),
102 SYM_VISIBILITY(STV_INTERNAL),
103 SYM_VISIBILITY(STV_HIDDEN),
104 SYM_VISIBILITY(STV_PROTECTED),
105 #undef SYM_VISIBILITY
107 const char *name = "unknown sym visibility name";
108 if (visibility < ARRAY_SIZE(visibility_name)) {
109 name = visibility_name[visibility];
114 static const char *rel_type(unsigned type)
116 static const char *type_name[] = {
117 #define REL_TYPE(X) [X] = #X
118 REL_TYPE(R_386_NONE),
120 REL_TYPE(R_386_PC32),
121 REL_TYPE(R_386_GOT32),
122 REL_TYPE(R_386_PLT32),
123 REL_TYPE(R_386_COPY),
124 REL_TYPE(R_386_GLOB_DAT),
125 REL_TYPE(R_386_JMP_SLOT),
126 REL_TYPE(R_386_RELATIVE),
127 REL_TYPE(R_386_GOTOFF),
128 REL_TYPE(R_386_GOTPC),
131 const char *name = "unknown type rel type name";
132 if (type < ARRAY_SIZE(type_name)) {
133 name = type_name[type];
138 static const char *sec_name(unsigned shndx)
140 const char *sec_strtab;
142 sec_strtab = strtab[ehdr.e_shstrndx];
144 if (shndx < ehdr.e_shnum) {
145 name = sec_strtab + shdr[shndx].sh_name;
147 else if (shndx == SHN_ABS) {
150 else if (shndx == SHN_COMMON) {
156 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
161 name = sym_strtab + sym->st_name;
164 name = sec_name(shdr[sym->st_shndx].sh_name);
171 #if BYTE_ORDER == LITTLE_ENDIAN
172 #define le16_to_cpu(val) (val)
173 #define le32_to_cpu(val) (val)
175 #if BYTE_ORDER == BIG_ENDIAN
176 #define le16_to_cpu(val) bswap_16(val)
177 #define le32_to_cpu(val) bswap_32(val)
180 static uint16_t elf16_to_cpu(uint16_t val)
182 return le16_to_cpu(val);
185 static uint32_t elf32_to_cpu(uint32_t val)
187 return le32_to_cpu(val);
190 static void read_ehdr(FILE *fp)
192 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
193 die("Cannot read ELF header: %s\n",
196 if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
197 die("No ELF magic\n");
199 if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
200 die("Not a 32 bit executable\n");
202 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
203 die("Not a LSB ELF executable\n");
205 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
206 die("Unknown ELF version\n");
208 /* Convert the fields to native endian */
209 ehdr.e_type = elf16_to_cpu(ehdr.e_type);
210 ehdr.e_machine = elf16_to_cpu(ehdr.e_machine);
211 ehdr.e_version = elf32_to_cpu(ehdr.e_version);
212 ehdr.e_entry = elf32_to_cpu(ehdr.e_entry);
213 ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff);
214 ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff);
215 ehdr.e_flags = elf32_to_cpu(ehdr.e_flags);
216 ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize);
217 ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
218 ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum);
219 ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
220 ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum);
221 ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx);
223 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
224 die("Unsupported ELF header type\n");
226 if (ehdr.e_machine != EM_386) {
227 die("Not for x86\n");
229 if (ehdr.e_version != EV_CURRENT) {
230 die("Unknown ELF version\n");
232 if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
233 die("Bad Elf header size\n");
235 if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
236 die("Bad program header entry\n");
238 if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
239 die("Bad section header entry\n");
241 if (ehdr.e_shstrndx >= ehdr.e_shnum) {
242 die("String table index out of bounds\n");
246 static void read_shdrs(FILE *fp)
249 if (ehdr.e_shnum > MAX_SHDRS) {
250 die("%d section headers supported: %d\n",
251 ehdr.e_shnum, MAX_SHDRS);
253 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
254 die("Seek to %d failed: %s\n",
255 ehdr.e_shoff, strerror(errno));
257 if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
258 die("Cannot read ELF section headers: %s\n",
261 for(i = 0; i < ehdr.e_shnum; i++) {
262 shdr[i].sh_name = elf32_to_cpu(shdr[i].sh_name);
263 shdr[i].sh_type = elf32_to_cpu(shdr[i].sh_type);
264 shdr[i].sh_flags = elf32_to_cpu(shdr[i].sh_flags);
265 shdr[i].sh_addr = elf32_to_cpu(shdr[i].sh_addr);
266 shdr[i].sh_offset = elf32_to_cpu(shdr[i].sh_offset);
267 shdr[i].sh_size = elf32_to_cpu(shdr[i].sh_size);
268 shdr[i].sh_link = elf32_to_cpu(shdr[i].sh_link);
269 shdr[i].sh_info = elf32_to_cpu(shdr[i].sh_info);
270 shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
271 shdr[i].sh_entsize = elf32_to_cpu(shdr[i].sh_entsize);
276 static void read_strtabs(FILE *fp)
279 for(i = 0; i < ehdr.e_shnum; i++) {
280 if (shdr[i].sh_type != SHT_STRTAB) {
283 strtab[i] = malloc(shdr[i].sh_size);
285 die("malloc of %d bytes for strtab failed\n",
288 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
289 die("Seek to %d failed: %s\n",
290 shdr[i].sh_offset, strerror(errno));
292 if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
293 die("Cannot read symbol table: %s\n",
299 static void read_symtabs(FILE *fp)
302 for(i = 0; i < ehdr.e_shnum; i++) {
303 if (shdr[i].sh_type != SHT_SYMTAB) {
306 symtab[i] = malloc(shdr[i].sh_size);
308 die("malloc of %d bytes for symtab failed\n",
311 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
312 die("Seek to %d failed: %s\n",
313 shdr[i].sh_offset, strerror(errno));
315 if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
316 die("Cannot read symbol table: %s\n",
319 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
320 symtab[i][j].st_name = elf32_to_cpu(symtab[i][j].st_name);
321 symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
322 symtab[i][j].st_size = elf32_to_cpu(symtab[i][j].st_size);
323 symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
329 static void read_relocs(FILE *fp)
332 for(i = 0; i < ehdr.e_shnum; i++) {
333 if (shdr[i].sh_type != SHT_REL) {
336 reltab[i] = malloc(shdr[i].sh_size);
338 die("malloc of %d bytes for relocs failed\n",
341 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
342 die("Seek to %d failed: %s\n",
343 shdr[i].sh_offset, strerror(errno));
345 if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
346 die("Cannot read symbol table: %s\n",
349 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
350 reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
351 reltab[i][j].r_info = elf32_to_cpu(reltab[i][j].r_info);
357 static void print_absolute_symbols(void)
360 printf("Absolute symbols\n");
361 printf(" Num: Value Size Type Bind Visibility Name\n");
362 for(i = 0; i < ehdr.e_shnum; i++) {
364 Elf32_Sym *sh_symtab;
366 if (shdr[i].sh_type != SHT_SYMTAB) {
369 sh_symtab = symtab[i];
370 sym_strtab = strtab[shdr[i].sh_link];
371 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
375 name = sym_name(sym_strtab, sym);
376 if (sym->st_shndx != SHN_ABS) {
379 printf("%5d %08x %5d %10s %10s %12s %s\n",
380 j, sym->st_value, sym->st_size,
381 sym_type(ELF32_ST_TYPE(sym->st_info)),
382 sym_bind(ELF32_ST_BIND(sym->st_info)),
383 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
390 static void print_absolute_relocs(void)
394 for(i = 0; i < ehdr.e_shnum; i++) {
396 Elf32_Sym *sh_symtab;
397 unsigned sec_applies, sec_symtab;
399 if (shdr[i].sh_type != SHT_REL) {
402 sec_symtab = shdr[i].sh_link;
403 sec_applies = shdr[i].sh_info;
404 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
407 sh_symtab = symtab[sec_symtab];
408 sym_strtab = strtab[shdr[sec_symtab].sh_link];
409 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
414 sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
415 name = sym_name(sym_strtab, sym);
416 if (sym->st_shndx != SHN_ABS) {
420 /* Absolute symbols are not relocated if bzImage is
421 * loaded at a non-compiled address. Display a warning
422 * to user at compile time about the absolute
423 * relocations present.
425 * User need to audit the code to make sure
426 * some symbols which should have been section
427 * relative have not become absolute because of some
428 * linker optimization or wrong programming usage.
430 * Before warning check if this absolute symbol
431 * relocation is harmless.
433 if (is_safe_abs_reloc(name))
437 printf("WARNING: Absolute relocations"
439 printf("Offset Info Type Sym.Value "
444 printf("%08x %08x %10s %08x %s\n",
447 rel_type(ELF32_R_TYPE(rel->r_info)),
457 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
460 /* Walk through the relocations */
461 for(i = 0; i < ehdr.e_shnum; i++) {
463 Elf32_Sym *sh_symtab;
464 unsigned sec_applies, sec_symtab;
466 if (shdr[i].sh_type != SHT_REL) {
469 sec_symtab = shdr[i].sh_link;
470 sec_applies = shdr[i].sh_info;
471 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
474 sh_symtab = symtab[sec_symtab];
475 sym_strtab = strtab[shdr[sec_symtab].sh_link];
476 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
481 sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
482 r_type = ELF32_R_TYPE(rel->r_info);
483 /* Don't visit relocations to absolute symbols */
484 if (sym->st_shndx == SHN_ABS) {
487 if (r_type == R_386_PC32) {
488 /* PC relative relocations don't need to be adjusted */
490 else if (r_type == R_386_32) {
491 /* Visit relocations that need to be adjusted */
495 die("Unsupported relocation type: %d\n", r_type);
501 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
506 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
508 /* Remember the address that needs to be adjusted. */
509 relocs[reloc_idx++] = rel->r_offset;
512 static int cmp_relocs(const void *va, const void *vb)
514 const unsigned long *a, *b;
516 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
519 static void emit_relocs(int as_text)
522 /* Count how many relocations I have and allocate space for them. */
524 walk_relocs(count_reloc);
525 relocs = malloc(reloc_count * sizeof(relocs[0]));
527 die("malloc of %d entries for relocs failed\n",
530 /* Collect up the relocations */
532 walk_relocs(collect_reloc);
534 /* Order the relocations for more efficient processing */
535 qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
537 /* Print the relocations */
539 /* Print the relocations in a form suitable that
542 printf(".section \".data.reloc\",\"a\"\n");
543 printf(".balign 4\n");
544 for(i = 0; i < reloc_count; i++) {
545 printf("\t .long 0x%08lx\n", relocs[i]);
550 unsigned char buf[4];
551 buf[0] = buf[1] = buf[2] = buf[3] = 0;
553 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
554 /* Now print each relocation */
555 for(i = 0; i < reloc_count; i++) {
556 buf[0] = (relocs[i] >> 0) & 0xff;
557 buf[1] = (relocs[i] >> 8) & 0xff;
558 buf[2] = (relocs[i] >> 16) & 0xff;
559 buf[3] = (relocs[i] >> 24) & 0xff;
560 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
565 static void usage(void)
567 die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
570 int main(int argc, char **argv)
572 int show_absolute_syms, show_absolute_relocs;
578 show_absolute_syms = 0;
579 show_absolute_relocs = 0;
582 for(i = 1; i < argc; i++) {
585 if (strcmp(argv[1], "--abs-syms") == 0) {
586 show_absolute_syms = 1;
590 if (strcmp(argv[1], "--abs-relocs") == 0) {
591 show_absolute_relocs = 1;
594 else if (strcmp(argv[1], "--text") == 0) {
608 fp = fopen(fname, "r");
610 die("Cannot open %s: %s\n",
611 fname, strerror(errno));
618 if (show_absolute_syms) {
619 print_absolute_symbols();
622 if (show_absolute_relocs) {
623 print_absolute_relocs();
626 emit_relocs(as_text);