Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm
[linux-2.6] / arch / x86 / 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                 "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 }