elfinterp.c 12 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405
  1. /* vi: set sw=4 ts=4: */
  2. /* ARM ELF shared library loader suppport
  3. *
  4. * Copyright (C) 2001-2004 Erik Andersen
  5. *
  6. * All rights reserved.
  7. *
  8. * Redistribution and use in source and binary forms, with or without
  9. * modification, are permitted provided that the following conditions
  10. * are met:
  11. * 1. Redistributions of source code must retain the above copyright
  12. * notice, this list of conditions and the following disclaimer.
  13. * 2. The name of the above contributors may not be
  14. * used to endorse or promote products derived from this software
  15. * without specific prior written permission.
  16. *
  17. * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
  18. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20. * ARE DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
  21. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27. * SUCH DAMAGE.
  28. */
  29. #if defined (__SUPPORT_LD_DEBUG__)
  30. static const char *_dl_reltypes_tab[] =
  31. {
  32. [0] "R_ARM_NONE", "R_ARM_PC24", "R_ARM_ABS32", "R_ARM_REL32",
  33. [4] "R_ARM_PC13", "R_ARM_ABS16", "R_ARM_ABS12", "R_ARM_THM_ABS5",
  34. [8] "R_ARM_ABS8", "R_ARM_SBREL32","R_ARM_THM_PC22", "R_ARM_THM_PC8",
  35. [12] "R_ARM_AMP_VCALL9", "R_ARM_SWI24", "R_ARM_THM_SWI8", "R_ARM_XPC25",
  36. [16] "R_ARM_THM_XPC22",
  37. [20] "R_ARM_COPY", "R_ARM_GLOB_DAT","R_ARM_JUMP_SLOT", "R_ARM_RELATIVE",
  38. [24] "R_ARM_GOTOFF", "R_ARM_GOTPC", "R_ARM_GOT32", "R_ARM_PLT32",
  39. [32] "R_ARM_ALU_PCREL_7_0","R_ARM_ALU_PCREL_15_8","R_ARM_ALU_PCREL_23_15","R_ARM_LDR_SBREL_11_0",
  40. [36] "R_ARM_ALU_SBREL_19_12","R_ARM_ALU_SBREL_27_20",
  41. [100] "R_ARM_GNU_VTENTRY","R_ARM_GNU_VTINHERIT","R_ARM_THM_PC11","R_ARM_THM_PC9",
  42. [249] "R_ARM_RXPC25", "R_ARM_RSBREL32", "R_ARM_THM_RPC22", "R_ARM_RREL32",
  43. [253] "R_ARM_RABS22", "R_ARM_RPC24", "R_ARM_RBASE",
  44. };
  45. static const char *
  46. _dl_reltypes(int type)
  47. {
  48. static char buf[22];
  49. const char *str;
  50. if (type >= (sizeof (_dl_reltypes_tab)/sizeof(_dl_reltypes_tab[0])) ||
  51. NULL == (str = _dl_reltypes_tab[type]))
  52. {
  53. str =_dl_simple_ltoa( buf, (unsigned long)(type));
  54. }
  55. return str;
  56. }
  57. static
  58. void debug_sym(Elf32_Sym *symtab,char *strtab,int symtab_index)
  59. {
  60. if(_dl_debug_symbols)
  61. {
  62. if(symtab_index){
  63. _dl_dprintf(_dl_debug_file, "\n%s\tvalue=%x\tsize=%x\tinfo=%x\tother=%x\tshndx=%x",
  64. strtab + symtab[symtab_index].st_name,
  65. symtab[symtab_index].st_value,
  66. symtab[symtab_index].st_size,
  67. symtab[symtab_index].st_info,
  68. symtab[symtab_index].st_other,
  69. symtab[symtab_index].st_shndx);
  70. }
  71. }
  72. }
  73. static void debug_reloc(Elf32_Sym *symtab,char *strtab, ELF_RELOC *rpnt)
  74. {
  75. if(_dl_debug_reloc)
  76. {
  77. int symtab_index;
  78. const char *sym;
  79. symtab_index = ELF32_R_SYM(rpnt->r_info);
  80. sym = symtab_index ? strtab + symtab[symtab_index].st_name : "sym=0x0";
  81. #ifdef ELF_USES_RELOCA
  82. _dl_dprintf(_dl_debug_file, "\n%s\toffset=%x\taddend=%x %s",
  83. _dl_reltypes(ELF32_R_TYPE(rpnt->r_info)),
  84. rpnt->r_offset,
  85. rpnt->r_addend,
  86. sym);
  87. #else
  88. _dl_dprintf(_dl_debug_file, "\n%s\toffset=%x %s",
  89. _dl_reltypes(ELF32_R_TYPE(rpnt->r_info)),
  90. rpnt->r_offset,
  91. sym);
  92. #endif
  93. }
  94. }
  95. #endif
  96. /* Program to load an ELF binary on a linux system, and run it.
  97. References to symbols in sharable libraries can be resolved by either
  98. an ELF sharable library or a linux style of shared library. */
  99. /* Disclaimer: I have never seen any AT&T source code for SVr4, nor have
  100. I ever taken any courses on internals. This program was developed using
  101. information available through the book "UNIX SYSTEM V RELEASE 4,
  102. Programmers guide: Ansi C and Programming Support Tools", which did
  103. a more than adequate job of explaining everything required to get this
  104. working. */
  105. extern int _dl_linux_resolve(void);
  106. unsigned long _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
  107. {
  108. int reloc_type;
  109. ELF_RELOC *this_reloc;
  110. char *strtab;
  111. char *symname;
  112. Elf32_Sym *symtab;
  113. ELF_RELOC *rel_addr;
  114. int symtab_index;
  115. char *new_addr;
  116. char **got_addr;
  117. unsigned long instr_addr;
  118. rel_addr = (ELF_RELOC *) tpnt->dynamic_info[DT_JMPREL];
  119. this_reloc = rel_addr + (reloc_entry >> 3);
  120. reloc_type = ELF32_R_TYPE(this_reloc->r_info);
  121. symtab_index = ELF32_R_SYM(this_reloc->r_info);
  122. symtab = (Elf32_Sym *) tpnt->dynamic_info[DT_SYMTAB];
  123. strtab = (char *) tpnt->dynamic_info[DT_STRTAB];
  124. symname = strtab + symtab[symtab_index].st_name;
  125. if (unlikely(reloc_type != R_ARM_JUMP_SLOT)) {
  126. _dl_dprintf(2, "%s: Incorrect relocation type in jump relocations\n",
  127. _dl_progname);
  128. _dl_exit(1);
  129. };
  130. /* Address of jump instruction to fix up */
  131. instr_addr = ((unsigned long) this_reloc->r_offset +
  132. (unsigned long) tpnt->loadaddr);
  133. got_addr = (char **) instr_addr;
  134. /* Get the address of the GOT entry */
  135. new_addr = _dl_find_hash(symname, tpnt->symbol_scope,
  136. tpnt, ELF_RTYPE_CLASS_PLT);
  137. if (unlikely(!new_addr)) {
  138. _dl_dprintf(2, "%s: can't resolve symbol '%s'\n",
  139. _dl_progname, symname);
  140. _dl_exit(1);
  141. };
  142. #if defined (__SUPPORT_LD_DEBUG__)
  143. if ((unsigned long) got_addr < 0x40000000)
  144. {
  145. if (_dl_debug_bindings)
  146. {
  147. _dl_dprintf(_dl_debug_file, "\nresolve function: %s", symname);
  148. if(_dl_debug_detail) _dl_dprintf(_dl_debug_file,
  149. "\tpatch %x ==> %x @ %x", *got_addr, new_addr, got_addr);
  150. }
  151. }
  152. if (!_dl_debug_nofixups) {
  153. *got_addr = new_addr;
  154. }
  155. #else
  156. *got_addr = new_addr;
  157. #endif
  158. return (unsigned long) new_addr;
  159. }
  160. static int
  161. _dl_parse(struct elf_resolve *tpnt, struct dyn_elf *scope,
  162. unsigned long rel_addr, unsigned long rel_size,
  163. int (*reloc_fnc) (struct elf_resolve *tpnt, struct dyn_elf *scope,
  164. ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab))
  165. {
  166. int i;
  167. char *strtab;
  168. int goof = 0;
  169. Elf32_Sym *symtab;
  170. ELF_RELOC *rpnt;
  171. int symtab_index;
  172. /* Now parse the relocation information */
  173. rpnt = (ELF_RELOC *) rel_addr;
  174. rel_size = rel_size / sizeof(ELF_RELOC);
  175. symtab = (Elf32_Sym *) tpnt->dynamic_info[DT_SYMTAB];
  176. strtab = (char *) tpnt->dynamic_info[DT_STRTAB];
  177. for (i = 0; i < rel_size; i++, rpnt++) {
  178. int res;
  179. symtab_index = ELF32_R_SYM(rpnt->r_info);
  180. #if defined (__SUPPORT_LD_DEBUG__)
  181. debug_sym(symtab,strtab,symtab_index);
  182. debug_reloc(symtab,strtab,rpnt);
  183. #endif
  184. res = reloc_fnc (tpnt, scope, rpnt, symtab, strtab);
  185. if (res==0) continue;
  186. _dl_dprintf(2, "\n%s: ",_dl_progname);
  187. if (symtab_index)
  188. _dl_dprintf(2, "symbol '%s': ", strtab + symtab[symtab_index].st_name);
  189. if (unlikely(res <0))
  190. {
  191. int reloc_type = ELF32_R_TYPE(rpnt->r_info);
  192. #if defined (__SUPPORT_LD_DEBUG__)
  193. _dl_dprintf(2, "can't handle reloc type %s\n ", _dl_reltypes(reloc_type));
  194. #else
  195. _dl_dprintf(2, "can't handle reloc type %x\n", reloc_type);
  196. #endif
  197. _dl_exit(-res);
  198. }
  199. if (unlikely(res >0))
  200. {
  201. _dl_dprintf(2, "can't resolve symbol\n");
  202. goof += res;
  203. }
  204. }
  205. return goof;
  206. }
  207. #if 0
  208. static unsigned long
  209. fix_bad_pc24 (unsigned long *const reloc_addr, unsigned long value)
  210. {
  211. static void *fix_page;
  212. static unsigned int fix_offset;
  213. unsigned int *fix_address;
  214. if (! fix_page)
  215. {
  216. fix_page = _dl_mmap (NULL, PAGE_SIZE , PROT_READ | PROT_WRITE | PROT_EXEC,
  217. MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  218. fix_offset = 0;
  219. }
  220. fix_address = (unsigned int *)(fix_page + fix_offset);
  221. fix_address[0] = 0xe51ff004; /* ldr pc, [pc, #-4] */
  222. fix_address[1] = value;
  223. fix_offset += 8;
  224. if (fix_offset >= PAGE_SIZE)
  225. fix_page = NULL;
  226. return (unsigned long)fix_address;
  227. }
  228. #endif
  229. static int
  230. _dl_do_reloc (struct elf_resolve *tpnt,struct dyn_elf *scope,
  231. ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
  232. {
  233. int reloc_type;
  234. int symtab_index;
  235. unsigned long *reloc_addr;
  236. unsigned long symbol_addr;
  237. int goof = 0;
  238. reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
  239. reloc_type = ELF32_R_TYPE(rpnt->r_info);
  240. symtab_index = ELF32_R_SYM(rpnt->r_info);
  241. symbol_addr = 0;
  242. if (symtab_index) {
  243. symbol_addr = (unsigned long) _dl_find_hash(strtab + symtab[symtab_index].st_name,
  244. scope, tpnt, elf_machine_type_class(reloc_type));
  245. /*
  246. * We want to allow undefined references to weak symbols - this might
  247. * have been intentional. We should not be linking local symbols
  248. * here, so all bases should be covered.
  249. */
  250. if (!symbol_addr && ELF32_ST_BIND(symtab[symtab_index].st_info) != STB_WEAK) {
  251. _dl_dprintf (2, "%s: can't resolve symbol '%s'\n",
  252. _dl_progname, strtab + symtab[symtab_index].st_name);
  253. _dl_exit (1);
  254. }
  255. }
  256. #if defined (__SUPPORT_LD_DEBUG__)
  257. {
  258. unsigned long old_val = *reloc_addr;
  259. #endif
  260. switch (reloc_type) {
  261. case R_ARM_NONE:
  262. break;
  263. case R_ARM_ABS32:
  264. *reloc_addr += symbol_addr;
  265. break;
  266. case R_ARM_PC24:
  267. #if 0
  268. {
  269. unsigned long addend;
  270. long newvalue, topbits;
  271. addend = *reloc_addr & 0x00ffffff;
  272. if (addend & 0x00800000) addend |= 0xff000000;
  273. newvalue = symbol_addr - (unsigned long)reloc_addr + (addend << 2);
  274. topbits = newvalue & 0xfe000000;
  275. if (topbits != 0xfe000000 && topbits != 0x00000000)
  276. {
  277. newvalue = fix_bad_pc24(reloc_addr, symbol_addr)
  278. - (unsigned long)reloc_addr + (addend << 2);
  279. topbits = newvalue & 0xfe000000;
  280. if (unlikely(topbits != 0xfe000000 && topbits != 0x00000000))
  281. {
  282. _dl_dprintf(2,"symbol '%s': R_ARM_PC24 relocation out of range.",
  283. symtab[symtab_index].st_name);
  284. _dl_exit(1);
  285. }
  286. }
  287. newvalue >>= 2;
  288. symbol_addr = (*reloc_addr & 0xff000000) | (newvalue & 0x00ffffff);
  289. *reloc_addr = symbol_addr;
  290. break;
  291. }
  292. #else
  293. _dl_dprintf(2,"R_ARM_PC24: Compile shared libraries with -fPIC!\n");
  294. _dl_exit(1);
  295. #endif
  296. case R_ARM_GLOB_DAT:
  297. case R_ARM_JUMP_SLOT:
  298. *reloc_addr = symbol_addr;
  299. break;
  300. case R_ARM_RELATIVE:
  301. *reloc_addr += (unsigned long) tpnt->loadaddr;
  302. break;
  303. case R_ARM_COPY:
  304. _dl_memcpy((void *) reloc_addr,
  305. (void *) symbol_addr, symtab[symtab_index].st_size);
  306. break;
  307. default:
  308. return -1; /*call _dl_exit(1) */
  309. }
  310. #if defined (__SUPPORT_LD_DEBUG__)
  311. if(_dl_debug_reloc && _dl_debug_detail)
  312. _dl_dprintf(_dl_debug_file, "\tpatch: %x ==> %x @ %x", old_val, *reloc_addr, reloc_addr);
  313. }
  314. #endif
  315. return goof;
  316. }
  317. static int
  318. _dl_do_lazy_reloc (struct elf_resolve *tpnt, struct dyn_elf *scope,
  319. ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
  320. {
  321. int reloc_type;
  322. unsigned long *reloc_addr;
  323. reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
  324. reloc_type = ELF32_R_TYPE(rpnt->r_info);
  325. #if defined (__SUPPORT_LD_DEBUG__)
  326. {
  327. unsigned long old_val = *reloc_addr;
  328. #endif
  329. switch (reloc_type) {
  330. case R_ARM_NONE:
  331. break;
  332. case R_ARM_JUMP_SLOT:
  333. *reloc_addr += (unsigned long) tpnt->loadaddr;
  334. break;
  335. default:
  336. return -1; /*call _dl_exit(1) */
  337. }
  338. #if defined (__SUPPORT_LD_DEBUG__)
  339. if(_dl_debug_reloc && _dl_debug_detail)
  340. _dl_dprintf(_dl_debug_file, "\tpatch: %x ==> %x @ %x", old_val, *reloc_addr, reloc_addr);
  341. }
  342. #endif
  343. return 0;
  344. }
  345. void _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
  346. unsigned long rel_addr, unsigned long rel_size)
  347. {
  348. (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
  349. }
  350. int _dl_parse_relocation_information(struct dyn_elf *rpnt,
  351. unsigned long rel_addr, unsigned long rel_size)
  352. {
  353. return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size, _dl_do_reloc);
  354. }