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[] = {
30 "xen_irq_disable_direct_reloc",
31 "xen_save_fl_direct_reloc",
34 static int is_safe_abs_reloc(const char* sym_name)
38 for(i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
39 if (!strcmp(sym_name, safe_abs_relocs[i]))
43 if (strncmp(sym_name, "VDSO", 4) == 0)
45 if (strncmp(sym_name, "__crc_", 6) == 0)
50 static void die(char *fmt, ...)
54 vfprintf(stderr, fmt, ap);
59 static const char *sym_type(unsigned type)
61 static const char *type_name[] = {
62 #define SYM_TYPE(X) [X] = #X
66 SYM_TYPE(STT_SECTION),
72 const char *name = "unknown sym type name";
73 if (type < ARRAY_SIZE(type_name)) {
74 name = type_name[type];
79 static const char *sym_bind(unsigned bind)
81 static const char *bind_name[] = {
82 #define SYM_BIND(X) [X] = #X
88 const char *name = "unknown sym bind name";
89 if (bind < ARRAY_SIZE(bind_name)) {
90 name = bind_name[bind];
95 static const char *sym_visibility(unsigned visibility)
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
105 const char *name = "unknown sym visibility name";
106 if (visibility < ARRAY_SIZE(visibility_name)) {
107 name = visibility_name[visibility];
112 static const char *rel_type(unsigned type)
114 static const char *type_name[] = {
115 #define REL_TYPE(X) [X] = #X
116 REL_TYPE(R_386_NONE),
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),
129 const char *name = "unknown type rel type name";
130 if (type < ARRAY_SIZE(type_name)) {
131 name = type_name[type];
136 static const char *sec_name(unsigned shndx)
138 const char *sec_strtab;
140 sec_strtab = strtab[ehdr.e_shstrndx];
142 if (shndx < ehdr.e_shnum) {
143 name = sec_strtab + shdr[shndx].sh_name;
145 else if (shndx == SHN_ABS) {
148 else if (shndx == SHN_COMMON) {
154 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
159 name = sym_strtab + sym->st_name;
162 name = sec_name(shdr[sym->st_shndx].sh_name);
169 #if BYTE_ORDER == LITTLE_ENDIAN
170 #define le16_to_cpu(val) (val)
171 #define le32_to_cpu(val) (val)
173 #if BYTE_ORDER == BIG_ENDIAN
174 #define le16_to_cpu(val) bswap_16(val)
175 #define le32_to_cpu(val) bswap_32(val)
178 static uint16_t elf16_to_cpu(uint16_t val)
180 return le16_to_cpu(val);
183 static uint32_t elf32_to_cpu(uint32_t val)
185 return le32_to_cpu(val);
188 static void read_ehdr(FILE *fp)
190 if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
191 die("Cannot read ELF header: %s\n",
194 if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
195 die("No ELF magic\n");
197 if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
198 die("Not a 32 bit executable\n");
200 if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
201 die("Not a LSB ELF executable\n");
203 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
204 die("Unknown ELF version\n");
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);
221 if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
222 die("Unsupported ELF header type\n");
224 if (ehdr.e_machine != EM_386) {
225 die("Not for x86\n");
227 if (ehdr.e_version != EV_CURRENT) {
228 die("Unknown ELF version\n");
230 if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
231 die("Bad Elf header size\n");
233 if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
234 die("Bad program header entry\n");
236 if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
237 die("Bad section header entry\n");
239 if (ehdr.e_shstrndx >= ehdr.e_shnum) {
240 die("String table index out of bounds\n");
244 static void read_shdrs(FILE *fp)
247 if (ehdr.e_shnum > MAX_SHDRS) {
248 die("%d section headers supported: %d\n",
249 ehdr.e_shnum, MAX_SHDRS);
251 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
252 die("Seek to %d failed: %s\n",
253 ehdr.e_shoff, strerror(errno));
255 if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
256 die("Cannot read ELF section headers: %s\n",
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);
274 static void read_strtabs(FILE *fp)
277 for(i = 0; i < ehdr.e_shnum; i++) {
278 if (shdr[i].sh_type != SHT_STRTAB) {
281 strtab[i] = malloc(shdr[i].sh_size);
283 die("malloc of %d bytes for strtab failed\n",
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));
290 if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
291 die("Cannot read symbol table: %s\n",
297 static void read_symtabs(FILE *fp)
300 for(i = 0; i < ehdr.e_shnum; i++) {
301 if (shdr[i].sh_type != SHT_SYMTAB) {
304 symtab[i] = malloc(shdr[i].sh_size);
306 die("malloc of %d bytes for symtab failed\n",
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));
313 if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
314 die("Cannot read symbol table: %s\n",
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);
327 static void read_relocs(FILE *fp)
330 for(i = 0; i < ehdr.e_shnum; i++) {
331 if (shdr[i].sh_type != SHT_REL) {
334 reltab[i] = malloc(shdr[i].sh_size);
336 die("malloc of %d bytes for relocs failed\n",
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));
343 if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
344 die("Cannot read symbol table: %s\n",
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);
355 static void print_absolute_symbols(void)
358 printf("Absolute symbols\n");
359 printf(" Num: Value Size Type Bind Visibility Name\n");
360 for(i = 0; i < ehdr.e_shnum; i++) {
362 Elf32_Sym *sh_symtab;
364 if (shdr[i].sh_type != SHT_SYMTAB) {
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++) {
373 name = sym_name(sym_strtab, sym);
374 if (sym->st_shndx != SHN_ABS) {
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)),
388 static void print_absolute_relocs(void)
392 for(i = 0; i < ehdr.e_shnum; i++) {
394 Elf32_Sym *sh_symtab;
395 unsigned sec_applies, sec_symtab;
397 if (shdr[i].sh_type != SHT_REL) {
400 sec_symtab = shdr[i].sh_link;
401 sec_applies = shdr[i].sh_info;
402 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
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++) {
412 sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
413 name = sym_name(sym_strtab, sym);
414 if (sym->st_shndx != SHN_ABS) {
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.
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.
428 * Before warning check if this absolute symbol
429 * relocation is harmless.
431 if (is_safe_abs_reloc(name))
435 printf("WARNING: Absolute relocations"
437 printf("Offset Info Type Sym.Value "
442 printf("%08x %08x %10s %08x %s\n",
445 rel_type(ELF32_R_TYPE(rel->r_info)),
455 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
458 /* Walk through the relocations */
459 for(i = 0; i < ehdr.e_shnum; i++) {
461 Elf32_Sym *sh_symtab;
462 unsigned sec_applies, sec_symtab;
464 if (shdr[i].sh_type != SHT_REL) {
467 sec_symtab = shdr[i].sh_link;
468 sec_applies = shdr[i].sh_info;
469 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
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++) {
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) {
485 if (r_type == R_386_PC32) {
486 /* PC relative relocations don't need to be adjusted */
488 else if (r_type == R_386_32) {
489 /* Visit relocations that need to be adjusted */
493 die("Unsupported relocation type: %d\n", r_type);
499 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
504 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
506 /* Remember the address that needs to be adjusted. */
507 relocs[reloc_idx++] = rel->r_offset;
510 static int cmp_relocs(const void *va, const void *vb)
512 const unsigned long *a, *b;
514 return (*a == *b)? 0 : (*a > *b)? 1 : -1;
517 static void emit_relocs(int as_text)
520 /* Count how many relocations I have and allocate space for them. */
522 walk_relocs(count_reloc);
523 relocs = malloc(reloc_count * sizeof(relocs[0]));
525 die("malloc of %d entries for relocs failed\n",
528 /* Collect up the relocations */
530 walk_relocs(collect_reloc);
532 /* Order the relocations for more efficient processing */
533 qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
535 /* Print the relocations */
537 /* Print the relocations in a form suitable that
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]);
548 unsigned char buf[4];
549 buf[0] = buf[1] = buf[2] = buf[3] = 0;
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]);
563 static void usage(void)
565 die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
568 int main(int argc, char **argv)
570 int show_absolute_syms, show_absolute_relocs;
576 show_absolute_syms = 0;
577 show_absolute_relocs = 0;
580 for(i = 1; i < argc; i++) {
583 if (strcmp(argv[1], "--abs-syms") == 0) {
584 show_absolute_syms = 1;
588 if (strcmp(argv[1], "--abs-relocs") == 0) {
589 show_absolute_relocs = 1;
592 else if (strcmp(argv[1], "--text") == 0) {
606 fp = fopen(fname, "r");
608 die("Cannot open %s: %s\n",
609 fname, strerror(errno));
616 if (show_absolute_syms) {
617 print_absolute_symbols();
620 if (show_absolute_relocs) {
621 print_absolute_relocs();
624 emit_relocs(as_text);