Merge branch 'master' of ssh://master.kernel.org/pub/scm/linux/kernel/git/mchehab...
[linux-2.6] / arch / i386 / boot / compressed / relocs.c
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                 "__kernel_vsyscall",
31                 "__kernel_rt_sigreturn",
32                 "__kernel_sigreturn",
33                 "SYSENTER_RETURN",
34                 "xen_irq_disable_direct_reloc",
35                 "xen_save_fl_direct_reloc",
36 };
37
38 static int is_safe_abs_reloc(const char* sym_name)
39 {
40         int i, array_size;
41
42         array_size = sizeof(safe_abs_relocs)/sizeof(char*);
43
44         for(i = 0; i < array_size; i++) {
45                 if (!strcmp(sym_name, safe_abs_relocs[i]))
46                         /* Match found */
47                         return 1;
48         }
49         if (strncmp(sym_name, "__crc_", 6) == 0)
50                 return 1;
51         return 0;
52 }
53
54 static void die(char *fmt, ...)
55 {
56         va_list ap;
57         va_start(ap, fmt);
58         vfprintf(stderr, fmt, ap);
59         va_end(ap);
60         exit(1);
61 }
62
63 static const char *sym_type(unsigned type)
64 {
65         static const char *type_name[] = {
66 #define SYM_TYPE(X) [X] = #X
67                 SYM_TYPE(STT_NOTYPE),
68                 SYM_TYPE(STT_OBJECT),
69                 SYM_TYPE(STT_FUNC),
70                 SYM_TYPE(STT_SECTION),
71                 SYM_TYPE(STT_FILE),
72                 SYM_TYPE(STT_COMMON),
73                 SYM_TYPE(STT_TLS),
74 #undef SYM_TYPE
75         };
76         const char *name = "unknown sym type name";
77         if (type < ARRAY_SIZE(type_name)) {
78                 name = type_name[type];
79         }
80         return name;
81 }
82
83 static const char *sym_bind(unsigned bind)
84 {
85         static const char *bind_name[] = {
86 #define SYM_BIND(X) [X] = #X
87                 SYM_BIND(STB_LOCAL),
88                 SYM_BIND(STB_GLOBAL),
89                 SYM_BIND(STB_WEAK),
90 #undef SYM_BIND
91         };
92         const char *name = "unknown sym bind name";
93         if (bind < ARRAY_SIZE(bind_name)) {
94                 name = bind_name[bind];
95         }
96         return name;
97 }
98
99 static const char *sym_visibility(unsigned visibility)
100 {
101         static const char *visibility_name[] = {
102 #define SYM_VISIBILITY(X) [X] = #X
103                 SYM_VISIBILITY(STV_DEFAULT),
104                 SYM_VISIBILITY(STV_INTERNAL),
105                 SYM_VISIBILITY(STV_HIDDEN),
106                 SYM_VISIBILITY(STV_PROTECTED),
107 #undef SYM_VISIBILITY
108         };
109         const char *name = "unknown sym visibility name";
110         if (visibility < ARRAY_SIZE(visibility_name)) {
111                 name = visibility_name[visibility];
112         }
113         return name;
114 }
115
116 static const char *rel_type(unsigned type)
117 {
118         static const char *type_name[] = {
119 #define REL_TYPE(X) [X] = #X
120                 REL_TYPE(R_386_NONE),
121                 REL_TYPE(R_386_32),
122                 REL_TYPE(R_386_PC32),
123                 REL_TYPE(R_386_GOT32),
124                 REL_TYPE(R_386_PLT32),
125                 REL_TYPE(R_386_COPY),
126                 REL_TYPE(R_386_GLOB_DAT),
127                 REL_TYPE(R_386_JMP_SLOT),
128                 REL_TYPE(R_386_RELATIVE),
129                 REL_TYPE(R_386_GOTOFF),
130                 REL_TYPE(R_386_GOTPC),
131 #undef REL_TYPE
132         };
133         const char *name = "unknown type rel type name";
134         if (type < ARRAY_SIZE(type_name)) {
135                 name = type_name[type];
136         }
137         return name;
138 }
139
140 static const char *sec_name(unsigned shndx)
141 {
142         const char *sec_strtab;
143         const char *name;
144         sec_strtab = strtab[ehdr.e_shstrndx];
145         name = "<noname>";
146         if (shndx < ehdr.e_shnum) {
147                 name = sec_strtab + shdr[shndx].sh_name;
148         }
149         else if (shndx == SHN_ABS) {
150                 name = "ABSOLUTE";
151         }
152         else if (shndx == SHN_COMMON) {
153                 name = "COMMON";
154         }
155         return name;
156 }
157
158 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
159 {
160         const char *name;
161         name = "<noname>";
162         if (sym->st_name) {
163                 name = sym_strtab + sym->st_name;
164         }
165         else {
166                 name = sec_name(shdr[sym->st_shndx].sh_name);
167         }
168         return name;
169 }
170
171
172
173 #if BYTE_ORDER == LITTLE_ENDIAN
174 #define le16_to_cpu(val) (val)
175 #define le32_to_cpu(val) (val)
176 #endif
177 #if BYTE_ORDER == BIG_ENDIAN
178 #define le16_to_cpu(val) bswap_16(val)
179 #define le32_to_cpu(val) bswap_32(val)
180 #endif
181
182 static uint16_t elf16_to_cpu(uint16_t val)
183 {
184         return le16_to_cpu(val);
185 }
186
187 static uint32_t elf32_to_cpu(uint32_t val)
188 {
189         return le32_to_cpu(val);
190 }
191
192 static void read_ehdr(FILE *fp)
193 {
194         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
195                 die("Cannot read ELF header: %s\n",
196                         strerror(errno));
197         }
198         if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
199                 die("No ELF magic\n");
200         }
201         if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
202                 die("Not a 32 bit executable\n");
203         }
204         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
205                 die("Not a LSB ELF executable\n");
206         }
207         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
208                 die("Unknown ELF version\n");
209         }
210         /* Convert the fields to native endian */
211         ehdr.e_type      = elf16_to_cpu(ehdr.e_type);
212         ehdr.e_machine   = elf16_to_cpu(ehdr.e_machine);
213         ehdr.e_version   = elf32_to_cpu(ehdr.e_version);
214         ehdr.e_entry     = elf32_to_cpu(ehdr.e_entry);
215         ehdr.e_phoff     = elf32_to_cpu(ehdr.e_phoff);
216         ehdr.e_shoff     = elf32_to_cpu(ehdr.e_shoff);
217         ehdr.e_flags     = elf32_to_cpu(ehdr.e_flags);
218         ehdr.e_ehsize    = elf16_to_cpu(ehdr.e_ehsize);
219         ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
220         ehdr.e_phnum     = elf16_to_cpu(ehdr.e_phnum);
221         ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
222         ehdr.e_shnum     = elf16_to_cpu(ehdr.e_shnum);
223         ehdr.e_shstrndx  = elf16_to_cpu(ehdr.e_shstrndx);
224
225         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
226                 die("Unsupported ELF header type\n");
227         }
228         if (ehdr.e_machine != EM_386) {
229                 die("Not for x86\n");
230         }
231         if (ehdr.e_version != EV_CURRENT) {
232                 die("Unknown ELF version\n");
233         }
234         if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
235                 die("Bad Elf header size\n");
236         }
237         if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
238                 die("Bad program header entry\n");
239         }
240         if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
241                 die("Bad section header entry\n");
242         }
243         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
244                 die("String table index out of bounds\n");
245         }
246 }
247
248 static void read_shdrs(FILE *fp)
249 {
250         int i;
251         if (ehdr.e_shnum > MAX_SHDRS) {
252                 die("%d section headers supported: %d\n",
253                         ehdr.e_shnum, MAX_SHDRS);
254         }
255         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
256                 die("Seek to %d failed: %s\n",
257                         ehdr.e_shoff, strerror(errno));
258         }
259         if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
260                 die("Cannot read ELF section headers: %s\n",
261                         strerror(errno));
262         }
263         for(i = 0; i < ehdr.e_shnum; i++) {
264                 shdr[i].sh_name      = elf32_to_cpu(shdr[i].sh_name);
265                 shdr[i].sh_type      = elf32_to_cpu(shdr[i].sh_type);
266                 shdr[i].sh_flags     = elf32_to_cpu(shdr[i].sh_flags);
267                 shdr[i].sh_addr      = elf32_to_cpu(shdr[i].sh_addr);
268                 shdr[i].sh_offset    = elf32_to_cpu(shdr[i].sh_offset);
269                 shdr[i].sh_size      = elf32_to_cpu(shdr[i].sh_size);
270                 shdr[i].sh_link      = elf32_to_cpu(shdr[i].sh_link);
271                 shdr[i].sh_info      = elf32_to_cpu(shdr[i].sh_info);
272                 shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
273                 shdr[i].sh_entsize   = elf32_to_cpu(shdr[i].sh_entsize);
274         }
275
276 }
277
278 static void read_strtabs(FILE *fp)
279 {
280         int i;
281         for(i = 0; i < ehdr.e_shnum; i++) {
282                 if (shdr[i].sh_type != SHT_STRTAB) {
283                         continue;
284                 }
285                 strtab[i] = malloc(shdr[i].sh_size);
286                 if (!strtab[i]) {
287                         die("malloc of %d bytes for strtab failed\n",
288                                 shdr[i].sh_size);
289                 }
290                 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
291                         die("Seek to %d failed: %s\n",
292                                 shdr[i].sh_offset, strerror(errno));
293                 }
294                 if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
295                         die("Cannot read symbol table: %s\n",
296                                 strerror(errno));
297                 }
298         }
299 }
300
301 static void read_symtabs(FILE *fp)
302 {
303         int i,j;
304         for(i = 0; i < ehdr.e_shnum; i++) {
305                 if (shdr[i].sh_type != SHT_SYMTAB) {
306                         continue;
307                 }
308                 symtab[i] = malloc(shdr[i].sh_size);
309                 if (!symtab[i]) {
310                         die("malloc of %d bytes for symtab failed\n",
311                                 shdr[i].sh_size);
312                 }
313                 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
314                         die("Seek to %d failed: %s\n",
315                                 shdr[i].sh_offset, strerror(errno));
316                 }
317                 if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
318                         die("Cannot read symbol table: %s\n",
319                                 strerror(errno));
320                 }
321                 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
322                         symtab[i][j].st_name  = elf32_to_cpu(symtab[i][j].st_name);
323                         symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
324                         symtab[i][j].st_size  = elf32_to_cpu(symtab[i][j].st_size);
325                         symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
326                 }
327         }
328 }
329
330
331 static void read_relocs(FILE *fp)
332 {
333         int i,j;
334         for(i = 0; i < ehdr.e_shnum; i++) {
335                 if (shdr[i].sh_type != SHT_REL) {
336                         continue;
337                 }
338                 reltab[i] = malloc(shdr[i].sh_size);
339                 if (!reltab[i]) {
340                         die("malloc of %d bytes for relocs failed\n",
341                                 shdr[i].sh_size);
342                 }
343                 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
344                         die("Seek to %d failed: %s\n",
345                                 shdr[i].sh_offset, strerror(errno));
346                 }
347                 if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
348                         die("Cannot read symbol table: %s\n",
349                                 strerror(errno));
350                 }
351                 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
352                         reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
353                         reltab[i][j].r_info   = elf32_to_cpu(reltab[i][j].r_info);
354                 }
355         }
356 }
357
358
359 static void print_absolute_symbols(void)
360 {
361         int i;
362         printf("Absolute symbols\n");
363         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
364         for(i = 0; i < ehdr.e_shnum; i++) {
365                 char *sym_strtab;
366                 Elf32_Sym *sh_symtab;
367                 int j;
368                 if (shdr[i].sh_type != SHT_SYMTAB) {
369                         continue;
370                 }
371                 sh_symtab = symtab[i];
372                 sym_strtab = strtab[shdr[i].sh_link];
373                 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
374                         Elf32_Sym *sym;
375                         const char *name;
376                         sym = &symtab[i][j];
377                         name = sym_name(sym_strtab, sym);
378                         if (sym->st_shndx != SHN_ABS) {
379                                 continue;
380                         }
381                         printf("%5d %08x %5d %10s %10s %12s %s\n",
382                                 j, sym->st_value, sym->st_size,
383                                 sym_type(ELF32_ST_TYPE(sym->st_info)),
384                                 sym_bind(ELF32_ST_BIND(sym->st_info)),
385                                 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
386                                 name);
387                 }
388         }
389         printf("\n");
390 }
391
392 static void print_absolute_relocs(void)
393 {
394         int i, printed = 0;
395
396         for(i = 0; i < ehdr.e_shnum; i++) {
397                 char *sym_strtab;
398                 Elf32_Sym *sh_symtab;
399                 unsigned sec_applies, sec_symtab;
400                 int j;
401                 if (shdr[i].sh_type != SHT_REL) {
402                         continue;
403                 }
404                 sec_symtab  = shdr[i].sh_link;
405                 sec_applies = shdr[i].sh_info;
406                 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
407                         continue;
408                 }
409                 sh_symtab = symtab[sec_symtab];
410                 sym_strtab = strtab[shdr[sec_symtab].sh_link];
411                 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
412                         Elf32_Rel *rel;
413                         Elf32_Sym *sym;
414                         const char *name;
415                         rel = &reltab[i][j];
416                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
417                         name = sym_name(sym_strtab, sym);
418                         if (sym->st_shndx != SHN_ABS) {
419                                 continue;
420                         }
421
422                         /* Absolute symbols are not relocated if bzImage is
423                          * loaded at a non-compiled address. Display a warning
424                          * to user at compile time about the absolute
425                          * relocations present.
426                          *
427                          * User need to audit the code to make sure
428                          * some symbols which should have been section
429                          * relative have not become absolute because of some
430                          * linker optimization or wrong programming usage.
431                          *
432                          * Before warning check if this absolute symbol
433                          * relocation is harmless.
434                          */
435                         if (is_safe_abs_reloc(name))
436                                 continue;
437
438                         if (!printed) {
439                                 printf("WARNING: Absolute relocations"
440                                         " present\n");
441                                 printf("Offset     Info     Type     Sym.Value "
442                                         "Sym.Name\n");
443                                 printed = 1;
444                         }
445
446                         printf("%08x %08x %10s %08x  %s\n",
447                                 rel->r_offset,
448                                 rel->r_info,
449                                 rel_type(ELF32_R_TYPE(rel->r_info)),
450                                 sym->st_value,
451                                 name);
452                 }
453         }
454
455         if (printed)
456                 printf("\n");
457 }
458
459 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
460 {
461         int i;
462         /* Walk through the relocations */
463         for(i = 0; i < ehdr.e_shnum; i++) {
464                 char *sym_strtab;
465                 Elf32_Sym *sh_symtab;
466                 unsigned sec_applies, sec_symtab;
467                 int j;
468                 if (shdr[i].sh_type != SHT_REL) {
469                         continue;
470                 }
471                 sec_symtab  = shdr[i].sh_link;
472                 sec_applies = shdr[i].sh_info;
473                 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
474                         continue;
475                 }
476                 sh_symtab = symtab[sec_symtab];
477                 sym_strtab = strtab[shdr[sec_symtab].sh_link];
478                 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
479                         Elf32_Rel *rel;
480                         Elf32_Sym *sym;
481                         unsigned r_type;
482                         rel = &reltab[i][j];
483                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
484                         r_type = ELF32_R_TYPE(rel->r_info);
485                         /* Don't visit relocations to absolute symbols */
486                         if (sym->st_shndx == SHN_ABS) {
487                                 continue;
488                         }
489                         if (r_type == R_386_PC32) {
490                                 /* PC relative relocations don't need to be adjusted */
491                         }
492                         else if (r_type == R_386_32) {
493                                 /* Visit relocations that need to be adjusted */
494                                 visit(rel, sym);
495                         }
496                         else {
497                                 die("Unsupported relocation type: %d\n", r_type);
498                         }
499                 }
500         }
501 }
502
503 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
504 {
505         reloc_count += 1;
506 }
507
508 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
509 {
510         /* Remember the address that needs to be adjusted. */
511         relocs[reloc_idx++] = rel->r_offset;
512 }
513
514 static int cmp_relocs(const void *va, const void *vb)
515 {
516         const unsigned long *a, *b;
517         a = va; b = vb;
518         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
519 }
520
521 static void emit_relocs(int as_text)
522 {
523         int i;
524         /* Count how many relocations I have and allocate space for them. */
525         reloc_count = 0;
526         walk_relocs(count_reloc);
527         relocs = malloc(reloc_count * sizeof(relocs[0]));
528         if (!relocs) {
529                 die("malloc of %d entries for relocs failed\n",
530                         reloc_count);
531         }
532         /* Collect up the relocations */
533         reloc_idx = 0;
534         walk_relocs(collect_reloc);
535
536         /* Order the relocations for more efficient processing */
537         qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
538
539         /* Print the relocations */
540         if (as_text) {
541                 /* Print the relocations in a form suitable that
542                  * gas will like.
543                  */
544                 printf(".section \".data.reloc\",\"a\"\n");
545                 printf(".balign 4\n");
546                 for(i = 0; i < reloc_count; i++) {
547                         printf("\t .long 0x%08lx\n", relocs[i]);
548                 }
549                 printf("\n");
550         }
551         else {
552                 unsigned char buf[4];
553                 buf[0] = buf[1] = buf[2] = buf[3] = 0;
554                 /* Print a stop */
555                 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
556                 /* Now print each relocation */
557                 for(i = 0; i < reloc_count; i++) {
558                         buf[0] = (relocs[i] >>  0) & 0xff;
559                         buf[1] = (relocs[i] >>  8) & 0xff;
560                         buf[2] = (relocs[i] >> 16) & 0xff;
561                         buf[3] = (relocs[i] >> 24) & 0xff;
562                         printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
563                 }
564         }
565 }
566
567 static void usage(void)
568 {
569         die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
570 }
571
572 int main(int argc, char **argv)
573 {
574         int show_absolute_syms, show_absolute_relocs;
575         int as_text;
576         const char *fname;
577         FILE *fp;
578         int i;
579
580         show_absolute_syms = 0;
581         show_absolute_relocs = 0;
582         as_text = 0;
583         fname = NULL;
584         for(i = 1; i < argc; i++) {
585                 char *arg = argv[i];
586                 if (*arg == '-') {
587                         if (strcmp(argv[1], "--abs-syms") == 0) {
588                                 show_absolute_syms = 1;
589                                 continue;
590                         }
591
592                         if (strcmp(argv[1], "--abs-relocs") == 0) {
593                                 show_absolute_relocs = 1;
594                                 continue;
595                         }
596                         else if (strcmp(argv[1], "--text") == 0) {
597                                 as_text = 1;
598                                 continue;
599                         }
600                 }
601                 else if (!fname) {
602                         fname = arg;
603                         continue;
604                 }
605                 usage();
606         }
607         if (!fname) {
608                 usage();
609         }
610         fp = fopen(fname, "r");
611         if (!fp) {
612                 die("Cannot open %s: %s\n",
613                         fname, strerror(errno));
614         }
615         read_ehdr(fp);
616         read_shdrs(fp);
617         read_strtabs(fp);
618         read_symtabs(fp);
619         read_relocs(fp);
620         if (show_absolute_syms) {
621                 print_absolute_symbols();
622                 return 0;
623         }
624         if (show_absolute_relocs) {
625                 print_absolute_relocs();
626                 return 0;
627         }
628         emit_relocs(as_text);
629         return 0;
630 }