1 /* $NetBSD: mips_reloc.c,v 1.63 2014/08/25 20:40:52 joerg Exp $ */
2
3 /*
4 * Copyright 1997 Michael L. Hitch <mhitch@montana.edu>
5 * Portions copyright 2002 Charles M. Hannum <root@ihack.net>
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. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 #ifndef lint
33 __RCSID("$NetBSD: mips_reloc.c,v 1.63 2014/08/25 20:40:52 joerg Exp $");
34 #endif /* not lint */
35
36 #include <sys/types.h>
37 #include <sys/endian.h>
38 #include <sys/tls.h>
39
40 #include <stdlib.h>
41 #include <string.h>
42
43 #include "debug.h"
44 #include "rtld.h"
45
46 #ifdef __mips_o32
47 #define SUPPORT_OLD_BROKEN_LD
48 #endif
49
50 void _rtld_bind_start(void);
51 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
52 caddr_t _rtld_bind(Elf_Word, Elf_Addr, Elf_Addr, Elf_Addr);
53
54 /*
55 * It is possible for the compiler to emit relocations for unaligned data.
56 * We handle this situation with these inlines.
57 */
58
59 #if ELFSIZE == 64
60 /*
61 * ELF64 MIPS encodes the relocs uniquely. The first 32-bits of info contain
62 * the symbol index. The top 32-bits contain three relocation types encoded
63 * in big-endian integer with first relocation in LSB. This means for little
64 * endian we have to byte swap that interger (r_type).
65 */
66 #define Elf_Sxword Elf64_Sxword
67 #define ELF_R_NXTTYPE_64_P(r_type) ((((r_type) >> 8) & 0xff) == R_TYPE(64))
68 #if BYTE_ORDER == LITTLE_ENDIAN
69 #undef ELF_R_SYM
70 #undef ELF_R_TYPE
71 #define ELF_R_SYM(r_info) ((r_info) & 0xffffffff)
72 #define ELF_R_TYPE(r_info) bswap32((r_info) >> 32)
73 #endif
74 #else
75 #define ELF_R_NXTTYPE_64_P(r_type) (0)
76 #define Elf_Sxword Elf32_Sword
77 #endif
78 #define GOT1_MASK (~(Elf_Addr)0 >> 1)
79
80 static inline Elf_Sxword
load_ptr(void * where,size_t len)81 load_ptr(void *where, size_t len)
82 {
83 Elf_Sxword val;
84
85 if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
86 #if ELFSIZE == 64
87 if (len == sizeof(Elf_Sxword))
88 return *(Elf_Sxword *)where;
89 #endif
90 return *(Elf_Sword *)where;
91 }
92
93 val = 0;
94 #if BYTE_ORDER == LITTLE_ENDIAN
95 (void)memcpy(&val, where, len);
96 #endif
97 #if BYTE_ORDER == BIG_ENDIAN
98 (void)memcpy((uint8_t *)((&val)+1) - len, where, len);
99 #endif
100 return (len == sizeof(Elf_Sxword)) ? val : (Elf_Sword)val;
101 }
102
103 static inline void
store_ptr(void * where,Elf_Sxword val,size_t len)104 store_ptr(void *where, Elf_Sxword val, size_t len)
105 {
106 if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
107 #if ELFSIZE == 64
108 if (len == sizeof(Elf_Sxword)) {
109 *(Elf_Sxword *)where = val;
110 return;
111 }
112 #endif
113 *(Elf_Sword *)where = val;
114 return;
115 }
116 #if BYTE_ORDER == LITTLE_ENDIAN
117 (void)memcpy(where, &val, len);
118 #endif
119 #if BYTE_ORDER == BIG_ENDIAN
120 (void)memcpy(where, (const uint8_t *)((&val)+1) - len, len);
121 #endif
122 }
123
124
125 void
_rtld_setup_pltgot(const Obj_Entry * obj)126 _rtld_setup_pltgot(const Obj_Entry *obj)
127 {
128 obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start;
129 /* XXX only if obj->pltgot[1] & 0x80000000 ?? */
130 obj->pltgot[1] |= (Elf_Addr) obj;
131 }
132
133 void
_rtld_relocate_nonplt_self(Elf_Dyn * dynp,Elf_Addr relocbase)134 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
135 {
136 const Elf_Rel *rel = 0, *rellim;
137 Elf_Addr relsz = 0;
138 void *where;
139 const Elf_Sym *symtab = NULL, *sym;
140 Elf_Addr *got = NULL;
141 Elf_Word local_gotno = 0, symtabno = 0, gotsym = 0;
142 size_t i;
143
144 for (; dynp->d_tag != DT_NULL; dynp++) {
145 switch (dynp->d_tag) {
146 case DT_REL:
147 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
148 break;
149 case DT_RELSZ:
150 relsz = dynp->d_un.d_val;
151 break;
152 case DT_SYMTAB:
153 symtab = (const Elf_Sym *)(relocbase + dynp->d_un.d_ptr);
154 break;
155 case DT_PLTGOT:
156 got = (Elf_Addr *)(relocbase + dynp->d_un.d_ptr);
157 break;
158 case DT_MIPS_LOCAL_GOTNO:
159 local_gotno = dynp->d_un.d_val;
160 break;
161 case DT_MIPS_SYMTABNO:
162 symtabno = dynp->d_un.d_val;
163 break;
164 case DT_MIPS_GOTSYM:
165 gotsym = dynp->d_un.d_val;
166 break;
167 }
168 }
169
170 i = (got[1] & 0x80000000) ? 2 : 1;
171 /* Relocate the local GOT entries */
172 got += i;
173 for (; i < local_gotno; i++)
174 *got++ += relocbase;
175 sym = symtab + gotsym;
176 /* Now do the global GOT entries */
177 for (i = gotsym; i < symtabno; i++) {
178 *got = sym->st_value + relocbase;
179 ++sym;
180 ++got;
181 }
182
183 rellim = (const Elf_Rel *)((uintptr_t)rel + relsz);
184 for (; rel < rellim; rel++) {
185 Elf_Word r_symndx, r_type;
186
187 where = (void *)(relocbase + rel->r_offset);
188
189 r_symndx = ELF_R_SYM(rel->r_info);
190 r_type = ELF_R_TYPE(rel->r_info);
191
192 switch (r_type & 0xff) {
193 case R_TYPE(REL32): {
194 const size_t rlen =
195 ELF_R_NXTTYPE_64_P(r_type)
196 ? sizeof(Elf_Sxword)
197 : sizeof(Elf_Sword);
198 Elf_Sxword old = load_ptr(where, rlen);
199 Elf_Sxword val = old;
200 #if ELFSIZE == 64
201 assert(r_type == R_TYPE(REL32)
202 || r_type == (R_TYPE(REL32)|(R_TYPE(64) << 8)));
203 #endif
204 assert(r_symndx < gotsym);
205 sym = symtab + r_symndx;
206 assert(ELF_ST_BIND(sym->st_info) == STB_LOCAL);
207 val += relocbase;
208 store_ptr(where, val, sizeof(Elf_Sword));
209 rdbg(("REL32/L(%p) %p -> %p in <self>",
210 where, (void *)old, (void *)val));
211 store_ptr(where, val, rlen);
212 break;
213 }
214
215 case R_TYPE(GPREL32):
216 case R_TYPE(NONE):
217 break;
218
219
220 default:
221 abort();
222 }
223 }
224 }
225
226 int
_rtld_relocate_nonplt_objects(Obj_Entry * obj)227 _rtld_relocate_nonplt_objects(Obj_Entry *obj)
228 {
229 const Elf_Rel *rel;
230 Elf_Addr *got = obj->pltgot;
231 const Elf_Sym *sym, *def;
232 const Obj_Entry *defobj;
233 Elf_Word i;
234 #ifdef SUPPORT_OLD_BROKEN_LD
235 int broken;
236 #endif
237
238 #ifdef SUPPORT_OLD_BROKEN_LD
239 broken = 0;
240 sym = obj->symtab;
241 for (i = 1; i < 12; i++)
242 if (sym[i].st_info == ELF_ST_INFO(STB_LOCAL, STT_NOTYPE))
243 broken = 1;
244 dbg(("%s: broken=%d", obj->path, broken));
245 #endif
246
247 i = (got[1] & 0x80000000) ? 2 : 1;
248 /* Relocate the local GOT entries */
249 got += i;
250 for (; i < obj->local_gotno; i++)
251 *got++ += (Elf_Addr)obj->relocbase;
252 sym = obj->symtab + obj->gotsym;
253 /* Now do the global GOT entries */
254 for (i = obj->gotsym; i < obj->symtabno; i++) {
255 rdbg((" doing got %d sym %p (%s, %lx)", i - obj->gotsym, sym,
256 sym->st_name + obj->strtab, (u_long) *got));
257
258 #ifdef SUPPORT_OLD_BROKEN_LD
259 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
260 broken && sym->st_shndx == SHN_UNDEF) {
261 /*
262 * XXX DANGER WILL ROBINSON!
263 * You might think this is stupid, as it intentionally
264 * defeats lazy binding -- and you'd be right.
265 * Unfortunately, for lazy binding to work right, we
266 * need to a way to force the GOT slots used for
267 * function pointers to be resolved immediately. This
268 * is supposed to be done automatically by the linker,
269 * by not outputting a PLT slot and setting st_value
270 * to 0 if there are non-PLT references, but older
271 * versions of GNU ld do not do this.
272 */
273 def = _rtld_find_symdef(i, obj, &defobj, false);
274 if (def == NULL)
275 return -1;
276 *got = def->st_value + (Elf_Addr)defobj->relocbase;
277 } else
278 #endif
279 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
280 sym->st_value != 0 && sym->st_shndx == SHN_UNDEF) {
281 /*
282 * If there are non-PLT references to the function,
283 * st_value should be 0, forcing us to resolve the
284 * address immediately.
285 *
286 * XXX DANGER WILL ROBINSON!
287 * The linker is not outputting PLT slots for calls to
288 * functions that are defined in the same shared
289 * library. This is a bug, because it can screw up
290 * link ordering rules if the symbol is defined in
291 * more than one module. For now, if there is a
292 * definition, we fail the test above and force a full
293 * symbol lookup. This means that all intra-module
294 * calls are bound immediately. - mycroft, 2003/09/24
295 */
296 *got = sym->st_value + (Elf_Addr)obj->relocbase;
297 } else if (sym->st_info == ELF_ST_INFO(STB_GLOBAL, STT_SECTION)) {
298 /* Symbols with index SHN_ABS are not relocated. */
299 if (sym->st_shndx != SHN_ABS)
300 *got = sym->st_value +
301 (Elf_Addr)obj->relocbase;
302 } else {
303 def = _rtld_find_symdef(i, obj, &defobj, false);
304 if (def == NULL)
305 return -1;
306 *got = def->st_value + (Elf_Addr)defobj->relocbase;
307 }
308
309 rdbg((" --> now %lx", (u_long) *got));
310 ++sym;
311 ++got;
312 }
313
314 got = obj->pltgot;
315 for (rel = obj->rel; rel < obj->rellim; rel++) {
316 Elf_Word r_symndx, r_type;
317 void *where;
318
319 where = obj->relocbase + rel->r_offset;
320 r_symndx = ELF_R_SYM(rel->r_info);
321 r_type = ELF_R_TYPE(rel->r_info);
322
323 switch (r_type & 0xff) {
324 case R_TYPE(NONE):
325 break;
326
327 case R_TYPE(REL32): {
328 /* 32-bit PC-relative reference */
329 const size_t rlen =
330 ELF_R_NXTTYPE_64_P(r_type)
331 ? sizeof(Elf_Sxword)
332 : sizeof(Elf_Sword);
333 Elf_Sxword old = load_ptr(where, rlen);
334 Elf_Sxword val = old;
335
336 def = obj->symtab + r_symndx;
337
338 if (r_symndx >= obj->gotsym) {
339 val += got[obj->local_gotno + r_symndx - obj->gotsym];
340 rdbg(("REL32/G(%p) %p --> %p (%s) in %s",
341 where, (void *)old, (void *)val,
342 obj->strtab + def->st_name,
343 obj->path));
344 } else {
345 /*
346 * XXX: ABI DIFFERENCE!
347 *
348 * Old NetBSD binutils would generate shared
349 * libs with section-relative relocations being
350 * already adjusted for the start address of
351 * the section.
352 *
353 * New binutils, OTOH, generate shared libs
354 * with the same relocations being based at
355 * zero, so we need to add in the start address
356 * of the section.
357 *
358 * --rkb, Oct 6, 2001
359 */
360
361 if (def->st_info ==
362 ELF_ST_INFO(STB_LOCAL, STT_SECTION)
363 #ifdef SUPPORT_OLD_BROKEN_LD
364 && !broken
365 #endif
366 )
367 val += (Elf_Addr)def->st_value;
368
369 val += (Elf_Addr)obj->relocbase;
370
371 rdbg(("REL32/L(%p) %p -> %p (%s) in %s",
372 where, (void *)old, (void *)val,
373 obj->strtab + def->st_name, obj->path));
374 }
375 store_ptr(where, val, rlen);
376 break;
377 }
378
379 #if ELFSIZE == 64
380 case R_TYPE(TLS_DTPMOD64):
381 #else
382 case R_TYPE(TLS_DTPMOD32):
383 #endif
384 {
385 Elf_Addr old = load_ptr(where, ELFSIZE / 8);
386 Elf_Addr val = old;
387
388 def = _rtld_find_symdef(r_symndx, obj, &defobj, false);
389 if (def == NULL)
390 return -1;
391
392 val += (Elf_Addr)defobj->tlsindex;
393
394 store_ptr(where, val, ELFSIZE / 8);
395 rdbg(("DTPMOD %s in %s --> %p in %s",
396 obj->strtab + obj->symtab[r_symndx].st_name,
397 obj->path, (void *)old, defobj->path));
398 break;
399 }
400
401 #if ELFSIZE == 64
402 case R_TYPE(TLS_DTPREL64):
403 #else
404 case R_TYPE(TLS_DTPREL32):
405 #endif
406 {
407 Elf_Addr old = load_ptr(where, ELFSIZE / 8);
408 Elf_Addr val = old;
409
410 def = _rtld_find_symdef(r_symndx, obj, &defobj, false);
411 if (def == NULL)
412 return -1;
413
414 if (!defobj->tls_done && _rtld_tls_offset_allocate(obj))
415 return -1;
416
417 val += (Elf_Addr)def->st_value - TLS_DTV_OFFSET;
418 store_ptr(where, val, ELFSIZE / 8);
419
420 rdbg(("DTPREL %s in %s --> %p in %s",
421 obj->strtab + obj->symtab[r_symndx].st_name,
422 obj->path, (void *)old, defobj->path));
423 break;
424 }
425
426 #if ELFSIZE == 64
427 case R_TYPE(TLS_TPREL64):
428 #else
429 case R_TYPE(TLS_TPREL32):
430 #endif
431 {
432 Elf_Addr old = load_ptr(where, ELFSIZE / 8);
433 Elf_Addr val = old;
434
435 def = _rtld_find_symdef(r_symndx, obj, &defobj, false);
436 if (def == NULL)
437 return -1;
438
439 if (!defobj->tls_done && _rtld_tls_offset_allocate(obj))
440 return -1;
441
442 val += (Elf_Addr)(def->st_value + defobj->tlsoffset
443 - TLS_TP_OFFSET);
444 store_ptr(where, val, ELFSIZE / 8);
445
446 rdbg(("TPREL %s in %s --> %p in %s",
447 obj->strtab + obj->symtab[r_symndx].st_name,
448 obj->path, (void *)*where, defobj->path));
449 break;
450 }
451
452 default:
453 rdbg(("sym = %lu, type = %lu, offset = %p, "
454 "contents = %p, symbol = %s",
455 (u_long)r_symndx, (u_long)ELF_R_TYPE(rel->r_info),
456 (void *)rel->r_offset,
457 (void *)load_ptr(where, sizeof(Elf_Sword)),
458 obj->strtab + obj->symtab[r_symndx].st_name));
459 _rtld_error("%s: Unsupported relocation type %ld "
460 "in non-PLT relocations",
461 obj->path, (u_long) ELF_R_TYPE(rel->r_info));
462 return -1;
463 }
464 }
465
466 return 0;
467 }
468
469 int
_rtld_relocate_plt_lazy(const Obj_Entry * obj)470 _rtld_relocate_plt_lazy(const Obj_Entry *obj)
471 {
472 /* PLT fixups were done above in the GOT relocation. */
473 return 0;
474 }
475
476 static inline int
_rtld_relocate_plt_object(const Obj_Entry * obj,Elf_Word sym,Elf_Addr * tp)477 _rtld_relocate_plt_object(const Obj_Entry *obj, Elf_Word sym, Elf_Addr *tp)
478 {
479 Elf_Addr *got = obj->pltgot;
480 const Elf_Sym *def;
481 const Obj_Entry *defobj;
482 Elf_Addr new_value;
483
484 def = _rtld_find_plt_symdef(sym, obj, &defobj, tp != NULL);
485 if (__predict_false(def == NULL))
486 return -1;
487 if (__predict_false(def == &_rtld_sym_zero))
488 return 0;
489
490 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
491 if (tp == NULL)
492 return 0;
493 new_value = _rtld_resolve_ifunc(defobj, def);
494 } else {
495 new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
496 }
497 rdbg(("bind now/fixup in %s --> new=%p",
498 defobj->strtab + def->st_name, (void *)new_value));
499 got[obj->local_gotno + sym - obj->gotsym] = new_value;
500
501 if (tp)
502 *tp = new_value;
503 return 0;
504 }
505
506 caddr_t
_rtld_bind(Elf_Word a0,Elf_Addr a1,Elf_Addr a2,Elf_Addr a3)507 _rtld_bind(Elf_Word a0, Elf_Addr a1, Elf_Addr a2, Elf_Addr a3)
508 {
509 Elf_Addr *got = (Elf_Addr *)(a2 - 0x7ff0);
510 const Obj_Entry *obj = (Obj_Entry *)(got[1] & GOT1_MASK);
511 Elf_Addr new_value = 0; /* XXX gcc */
512 int err;
513
514 _rtld_shared_enter();
515 err = _rtld_relocate_plt_object(obj, a0, &new_value);
516 if (err)
517 _rtld_die();
518 _rtld_shared_exit();
519
520 return (caddr_t)new_value;
521 }
522
523 int
_rtld_relocate_plt_objects(const Obj_Entry * obj)524 _rtld_relocate_plt_objects(const Obj_Entry *obj)
525 {
526 const Elf_Sym *sym = obj->symtab + obj->gotsym;
527 Elf_Word i;
528
529 for (i = obj->gotsym; i < obj->symtabno; i++, sym++) {
530 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC)
531 if (_rtld_relocate_plt_object(obj, i, NULL) < 0)
532 return -1;
533 }
534
535 return 0;
536 }
537