FreeBSD/Linux Kernel Cross Reference
sys/kern/link_elf.c
1 /*-
2 * Copyright (c) 1998-2000 Doug Rabson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/6.1/sys/kern/link_elf.c 158179 2006-04-30 16:44:43Z cvs2svn $");
29
30 #include "opt_gdb.h"
31 #include "opt_mac.h"
32
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #ifdef GPROF
36 #include <sys/gmon.h>
37 #endif
38 #include <sys/kernel.h>
39 #include <sys/lock.h>
40 #include <sys/mac.h>
41 #include <sys/malloc.h>
42 #include <sys/mutex.h>
43 #include <sys/proc.h>
44 #include <sys/namei.h>
45 #include <sys/fcntl.h>
46 #include <sys/vnode.h>
47 #include <sys/linker.h>
48
49 #include <machine/elf.h>
50
51 #include <vm/vm.h>
52 #include <vm/vm_param.h>
53 #ifdef SPARSE_MAPPING
54 #include <vm/vm_object.h>
55 #include <vm/vm_kern.h>
56 #include <vm/vm_extern.h>
57 #endif
58 #include <vm/pmap.h>
59 #include <vm/vm_map.h>
60
61 #include <sys/link_elf.h>
62
63 #include "linker_if.h"
64
65 typedef struct elf_file {
66 struct linker_file lf; /* Common fields */
67 int preloaded; /* Was file pre-loaded */
68 caddr_t address; /* Relocation address */
69 #ifdef SPARSE_MAPPING
70 vm_object_t object; /* VM object to hold file pages */
71 #endif
72 Elf_Dyn* dynamic; /* Symbol table etc. */
73 Elf_Hashelt nbuckets; /* DT_HASH info */
74 Elf_Hashelt nchains;
75 const Elf_Hashelt* buckets;
76 const Elf_Hashelt* chains;
77 caddr_t hash;
78 caddr_t strtab; /* DT_STRTAB */
79 int strsz; /* DT_STRSZ */
80 const Elf_Sym* symtab; /* DT_SYMTAB */
81 Elf_Addr* got; /* DT_PLTGOT */
82 const Elf_Rel* pltrel; /* DT_JMPREL */
83 int pltrelsize; /* DT_PLTRELSZ */
84 const Elf_Rela* pltrela; /* DT_JMPREL */
85 int pltrelasize; /* DT_PLTRELSZ */
86 const Elf_Rel* rel; /* DT_REL */
87 int relsize; /* DT_RELSZ */
88 const Elf_Rela* rela; /* DT_RELA */
89 int relasize; /* DT_RELASZ */
90 caddr_t modptr;
91 const Elf_Sym* ddbsymtab; /* The symbol table we are using */
92 long ddbsymcnt; /* Number of symbols */
93 caddr_t ddbstrtab; /* String table */
94 long ddbstrcnt; /* number of bytes in string table */
95 caddr_t symbase; /* malloc'ed symbold base */
96 caddr_t strbase; /* malloc'ed string base */
97 #ifdef GDB
98 struct link_map gdb; /* hooks for gdb */
99 #endif
100 } *elf_file_t;
101
102 static int link_elf_link_common_finish(linker_file_t);
103 static int link_elf_link_preload(linker_class_t cls,
104 const char*, linker_file_t*);
105 static int link_elf_link_preload_finish(linker_file_t);
106 static int link_elf_load_file(linker_class_t, const char*, linker_file_t*);
107 static int link_elf_lookup_symbol(linker_file_t, const char*,
108 c_linker_sym_t*);
109 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
110 static int link_elf_search_symbol(linker_file_t, caddr_t value,
111 c_linker_sym_t* sym, long* diffp);
112
113 static void link_elf_unload_file(linker_file_t);
114 static void link_elf_unload_preload(linker_file_t);
115 static int link_elf_lookup_set(linker_file_t, const char *,
116 void ***, void ***, int *);
117 static int link_elf_each_function_name(linker_file_t,
118 int (*)(const char *, void *),
119 void *);
120 static void link_elf_reloc_local(linker_file_t);
121 static Elf_Addr elf_lookup(linker_file_t lf, Elf_Size symidx, int deps);
122
123 static kobj_method_t link_elf_methods[] = {
124 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
125 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
126 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
127 KOBJMETHOD(linker_unload, link_elf_unload_file),
128 KOBJMETHOD(linker_load_file, link_elf_load_file),
129 KOBJMETHOD(linker_link_preload, link_elf_link_preload),
130 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
131 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set),
132 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
133 { 0, 0 }
134 };
135
136 static struct linker_class link_elf_class = {
137 #if ELF_TARG_CLASS == ELFCLASS32
138 "elf32",
139 #else
140 "elf64",
141 #endif
142 link_elf_methods, sizeof(struct elf_file)
143 };
144
145 static int parse_dynamic(elf_file_t ef);
146 static int relocate_file(elf_file_t ef);
147 static int link_elf_preload_parse_symbols(elf_file_t ef);
148
149 #ifdef GDB
150 static void r_debug_state(struct r_debug *dummy_one,
151 struct link_map *dummy_two);
152
153 /*
154 * A list of loaded modules for GDB to use for loading symbols.
155 */
156 struct r_debug r_debug;
157
158 #define GDB_STATE(s) r_debug.r_state = s; r_debug_state(NULL, NULL);
159
160 /*
161 * Function for the debugger to set a breakpoint on to gain control.
162 */
163 static void
164 r_debug_state(struct r_debug *dummy_one __unused,
165 struct link_map *dummy_two __unused)
166 {
167 }
168
169 static void
170 link_elf_add_gdb(struct link_map *l)
171 {
172 struct link_map *prev;
173
174 l->l_next = NULL;
175
176 if (r_debug.r_map == NULL) {
177 /* Add first. */
178 l->l_prev = NULL;
179 r_debug.r_map = l;
180 } else {
181 /* Append to list. */
182 for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
183 ;
184 l->l_prev = prev;
185 prev->l_next = l;
186 }
187 }
188
189 static void
190 link_elf_delete_gdb(struct link_map *l)
191 {
192 if (l->l_prev == NULL) {
193 /* Remove first. */
194 if ((r_debug.r_map = l->l_next) != NULL)
195 l->l_next->l_prev = NULL;
196 } else {
197 /* Remove any but first. */
198 if ((l->l_prev->l_next = l->l_next) != NULL)
199 l->l_next->l_prev = l->l_prev;
200 }
201 }
202 #endif /* GDB */
203
204 #ifdef __ia64__
205 Elf_Addr link_elf_get_gp(linker_file_t);
206 #endif
207
208 /*
209 * The kernel symbol table starts here.
210 */
211 extern struct _dynamic _DYNAMIC;
212
213 static void
214 link_elf_error(const char *s)
215 {
216 printf("kldload: %s\n", s);
217 }
218
219 /*
220 * Actions performed after linking/loading both the preloaded kernel and any
221 * modules; whether preloaded or dynamicly loaded.
222 */
223 static int
224 link_elf_link_common_finish(linker_file_t lf)
225 {
226 #ifdef GDB
227 elf_file_t ef = (elf_file_t)lf;
228 char *newfilename;
229 #endif
230 int error;
231
232 /* Notify MD code that a module is being loaded. */
233 error = elf_cpu_load_file(lf);
234 if (error)
235 return (error);
236
237 #ifdef GDB
238 GDB_STATE(RT_ADD);
239 ef->gdb.l_addr = lf->address;
240 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
241 strcpy(newfilename, lf->filename);
242 ef->gdb.l_name = newfilename;
243 ef->gdb.l_ld = ef->dynamic;
244 link_elf_add_gdb(&ef->gdb);
245 GDB_STATE(RT_CONSISTENT);
246 #endif
247
248 return (0);
249 }
250
251 static void
252 link_elf_init(void* arg)
253 {
254 Elf_Dyn *dp;
255 caddr_t modptr, baseptr, sizeptr;
256 elf_file_t ef;
257 char *modname;
258
259 linker_add_class(&link_elf_class);
260
261 dp = (Elf_Dyn*) &_DYNAMIC;
262 modname = NULL;
263 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
264 if (modptr == NULL)
265 modptr = preload_search_by_type("elf kernel");
266 if (modptr)
267 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
268 if (modname == NULL)
269 modname = "kernel";
270 linker_kernel_file = linker_make_file(modname, &link_elf_class);
271 if (linker_kernel_file == NULL)
272 panic("link_elf_init: Can't create linker structures for kernel");
273
274 ef = (elf_file_t) linker_kernel_file;
275 ef->preloaded = 1;
276 ef->address = 0;
277 #ifdef SPARSE_MAPPING
278 ef->object = 0;
279 #endif
280 ef->dynamic = dp;
281
282 if (dp)
283 parse_dynamic(ef);
284 linker_kernel_file->address = (caddr_t) KERNBASE;
285 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
286
287 if (modptr) {
288 ef->modptr = modptr;
289 baseptr = preload_search_info(modptr, MODINFO_ADDR);
290 if (baseptr)
291 linker_kernel_file->address = *(caddr_t *)baseptr;
292 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
293 if (sizeptr)
294 linker_kernel_file->size = *(size_t *)sizeptr;
295 }
296 (void)link_elf_preload_parse_symbols(ef);
297
298 #ifdef GDB
299 r_debug.r_map = NULL;
300 r_debug.r_brk = r_debug_state;
301 r_debug.r_state = RT_CONSISTENT;
302 #endif
303
304 (void)link_elf_link_common_finish(linker_kernel_file);
305 }
306
307 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
308
309 static int
310 link_elf_preload_parse_symbols(elf_file_t ef)
311 {
312 caddr_t pointer;
313 caddr_t ssym, esym, base;
314 caddr_t strtab;
315 int strcnt;
316 Elf_Sym* symtab;
317 int symcnt;
318
319 if (ef->modptr == NULL)
320 return 0;
321 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
322 if (pointer == NULL)
323 return 0;
324 ssym = *(caddr_t *)pointer;
325 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
326 if (pointer == NULL)
327 return 0;
328 esym = *(caddr_t *)pointer;
329
330 base = ssym;
331
332 symcnt = *(long *)base;
333 base += sizeof(long);
334 symtab = (Elf_Sym *)base;
335 base += roundup(symcnt, sizeof(long));
336
337 if (base > esym || base < ssym) {
338 printf("Symbols are corrupt!\n");
339 return EINVAL;
340 }
341
342 strcnt = *(long *)base;
343 base += sizeof(long);
344 strtab = base;
345 base += roundup(strcnt, sizeof(long));
346
347 if (base > esym || base < ssym) {
348 printf("Symbols are corrupt!\n");
349 return EINVAL;
350 }
351
352 ef->ddbsymtab = symtab;
353 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
354 ef->ddbstrtab = strtab;
355 ef->ddbstrcnt = strcnt;
356
357 return 0;
358 }
359
360 static int
361 parse_dynamic(elf_file_t ef)
362 {
363 Elf_Dyn *dp;
364 int plttype = DT_REL;
365
366 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
367 switch (dp->d_tag) {
368 case DT_HASH:
369 {
370 /* From src/libexec/rtld-elf/rtld.c */
371 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
372 (ef->address + dp->d_un.d_ptr);
373 ef->nbuckets = hashtab[0];
374 ef->nchains = hashtab[1];
375 ef->buckets = hashtab + 2;
376 ef->chains = ef->buckets + ef->nbuckets;
377 break;
378 }
379 case DT_STRTAB:
380 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
381 break;
382 case DT_STRSZ:
383 ef->strsz = dp->d_un.d_val;
384 break;
385 case DT_SYMTAB:
386 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
387 break;
388 case DT_SYMENT:
389 if (dp->d_un.d_val != sizeof(Elf_Sym))
390 return ENOEXEC;
391 break;
392 case DT_PLTGOT:
393 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
394 break;
395 case DT_REL:
396 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
397 break;
398 case DT_RELSZ:
399 ef->relsize = dp->d_un.d_val;
400 break;
401 case DT_RELENT:
402 if (dp->d_un.d_val != sizeof(Elf_Rel))
403 return ENOEXEC;
404 break;
405 case DT_JMPREL:
406 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
407 break;
408 case DT_PLTRELSZ:
409 ef->pltrelsize = dp->d_un.d_val;
410 break;
411 case DT_RELA:
412 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
413 break;
414 case DT_RELASZ:
415 ef->relasize = dp->d_un.d_val;
416 break;
417 case DT_RELAENT:
418 if (dp->d_un.d_val != sizeof(Elf_Rela))
419 return ENOEXEC;
420 break;
421 case DT_PLTREL:
422 plttype = dp->d_un.d_val;
423 if (plttype != DT_REL && plttype != DT_RELA)
424 return ENOEXEC;
425 break;
426 #ifdef GDB
427 case DT_DEBUG:
428 dp->d_un.d_ptr = (Elf_Addr) &r_debug;
429 break;
430 #endif
431 }
432 }
433
434 if (plttype == DT_RELA) {
435 ef->pltrela = (const Elf_Rela *) ef->pltrel;
436 ef->pltrel = NULL;
437 ef->pltrelasize = ef->pltrelsize;
438 ef->pltrelsize = 0;
439 }
440
441 ef->ddbsymtab = ef->symtab;
442 ef->ddbsymcnt = ef->nchains;
443 ef->ddbstrtab = ef->strtab;
444 ef->ddbstrcnt = ef->strsz;
445
446 return 0;
447 }
448
449 static int
450 link_elf_link_preload(linker_class_t cls,
451 const char* filename, linker_file_t *result)
452 {
453 caddr_t modptr, baseptr, sizeptr, dynptr;
454 char *type;
455 elf_file_t ef;
456 linker_file_t lf;
457 int error;
458 vm_offset_t dp;
459
460 /* Look to see if we have the file preloaded */
461 modptr = preload_search_by_name(filename);
462 if (modptr == NULL)
463 return ENOENT;
464
465 type = (char *)preload_search_info(modptr, MODINFO_TYPE);
466 baseptr = preload_search_info(modptr, MODINFO_ADDR);
467 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
468 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
469 if (type == NULL ||
470 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
471 strcmp(type, "elf module") != 0))
472 return (EFTYPE);
473 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
474 return (EINVAL);
475
476 lf = linker_make_file(filename, &link_elf_class);
477 if (lf == NULL) {
478 return ENOMEM;
479 }
480
481 ef = (elf_file_t) lf;
482 ef->preloaded = 1;
483 ef->modptr = modptr;
484 ef->address = *(caddr_t *)baseptr;
485 #ifdef SPARSE_MAPPING
486 ef->object = 0;
487 #endif
488 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
489 ef->dynamic = (Elf_Dyn *)dp;
490 lf->address = ef->address;
491 lf->size = *(size_t *)sizeptr;
492
493 error = parse_dynamic(ef);
494 if (error) {
495 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
496 return error;
497 }
498 link_elf_reloc_local(lf);
499 *result = lf;
500 return (0);
501 }
502
503 static int
504 link_elf_link_preload_finish(linker_file_t lf)
505 {
506 elf_file_t ef;
507 int error;
508
509 ef = (elf_file_t) lf;
510 #if 0 /* this will be more trouble than it's worth for now */
511 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
512 if (dp->d_tag != DT_NEEDED)
513 continue;
514 modname = ef->strtab + dp->d_un.d_val;
515 error = linker_load_module(modname, lf);
516 if (error)
517 goto out;
518 }
519 #endif
520 error = relocate_file(ef);
521 if (error)
522 return error;
523 (void)link_elf_preload_parse_symbols(ef);
524
525 return (link_elf_link_common_finish(lf));
526 }
527
528 static int
529 link_elf_load_file(linker_class_t cls, const char* filename,
530 linker_file_t* result)
531 {
532 struct nameidata nd;
533 struct thread* td = curthread; /* XXX */
534 Elf_Ehdr *hdr;
535 caddr_t firstpage;
536 int nbytes, i;
537 Elf_Phdr *phdr;
538 Elf_Phdr *phlimit;
539 Elf_Phdr *segs[2];
540 int nsegs;
541 Elf_Phdr *phdyn;
542 Elf_Phdr *phphdr;
543 caddr_t mapbase;
544 size_t mapsize;
545 Elf_Off base_offset;
546 Elf_Addr base_vaddr;
547 Elf_Addr base_vlimit;
548 int error = 0;
549 int resid, flags;
550 elf_file_t ef;
551 linker_file_t lf;
552 Elf_Shdr *shdr;
553 int symtabindex;
554 int symstrindex;
555 int symcnt;
556 int strcnt;
557
558 GIANT_REQUIRED;
559
560 shdr = NULL;
561 lf = NULL;
562
563 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
564 flags = FREAD;
565 error = vn_open(&nd, &flags, 0, -1);
566 if (error)
567 return error;
568 NDFREE(&nd, NDF_ONLY_PNBUF);
569 #ifdef MAC
570 error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp);
571 if (error) {
572 firstpage = NULL;
573 goto out;
574 }
575 #endif
576
577 /*
578 * Read the elf header from the file.
579 */
580 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
581 if (firstpage == NULL) {
582 error = ENOMEM;
583 goto out;
584 }
585 hdr = (Elf_Ehdr *)firstpage;
586 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
587 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
588 &resid, td);
589 nbytes = PAGE_SIZE - resid;
590 if (error)
591 goto out;
592
593 if (!IS_ELF(*hdr)) {
594 error = ENOEXEC;
595 goto out;
596 }
597
598 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
599 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
600 link_elf_error("Unsupported file layout");
601 error = ENOEXEC;
602 goto out;
603 }
604 if (hdr->e_ident[EI_VERSION] != EV_CURRENT
605 || hdr->e_version != EV_CURRENT) {
606 link_elf_error("Unsupported file version");
607 error = ENOEXEC;
608 goto out;
609 }
610 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
611 link_elf_error("Unsupported file type");
612 error = ENOEXEC;
613 goto out;
614 }
615 if (hdr->e_machine != ELF_TARG_MACH) {
616 link_elf_error("Unsupported machine");
617 error = ENOEXEC;
618 goto out;
619 }
620
621 /*
622 * We rely on the program header being in the first page. This is
623 * not strictly required by the ABI specification, but it seems to
624 * always true in practice. And, it simplifies things considerably.
625 */
626 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
627 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
628 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
629 link_elf_error("Unreadable program headers");
630
631 /*
632 * Scan the program header entries, and save key information.
633 *
634 * We rely on there being exactly two load segments, text and data,
635 * in that order.
636 */
637 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
638 phlimit = phdr + hdr->e_phnum;
639 nsegs = 0;
640 phdyn = NULL;
641 phphdr = NULL;
642 while (phdr < phlimit) {
643 switch (phdr->p_type) {
644
645 case PT_LOAD:
646 if (nsegs == 2) {
647 link_elf_error("Too many sections");
648 error = ENOEXEC;
649 goto out;
650 }
651 /*
652 * XXX: We just trust they come in right order ??
653 */
654 segs[nsegs] = phdr;
655 ++nsegs;
656 break;
657
658 case PT_PHDR:
659 phphdr = phdr;
660 break;
661
662 case PT_DYNAMIC:
663 phdyn = phdr;
664 break;
665
666 case PT_INTERP:
667 link_elf_error("Unsupported file type");
668 error = ENOEXEC;
669 goto out;
670 }
671
672 ++phdr;
673 }
674 if (phdyn == NULL) {
675 link_elf_error("Object is not dynamically-linked");
676 error = ENOEXEC;
677 goto out;
678 }
679 if (nsegs != 2) {
680 link_elf_error("Too few sections");
681 error = ENOEXEC;
682 goto out;
683 }
684
685 /*
686 * Allocate the entire address space of the object, to stake out our
687 * contiguous region, and to establish the base address for relocation.
688 */
689 base_offset = trunc_page(segs[0]->p_offset);
690 base_vaddr = trunc_page(segs[0]->p_vaddr);
691 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
692 mapsize = base_vlimit - base_vaddr;
693
694 lf = linker_make_file(filename, &link_elf_class);
695 if (!lf) {
696 error = ENOMEM;
697 goto out;
698 }
699
700 ef = (elf_file_t) lf;
701 #ifdef SPARSE_MAPPING
702 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
703 if (ef->object == NULL) {
704 error = ENOMEM;
705 goto out;
706 }
707 ef->address = (caddr_t) vm_map_min(kernel_map);
708 error = vm_map_find(kernel_map, ef->object, 0,
709 (vm_offset_t *) &ef->address,
710 mapsize, 1,
711 VM_PROT_ALL, VM_PROT_ALL, 0);
712 if (error) {
713 vm_object_deallocate(ef->object);
714 ef->object = 0;
715 goto out;
716 }
717 #else
718 ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
719 if (!ef->address) {
720 error = ENOMEM;
721 goto out;
722 }
723 #endif
724 mapbase = ef->address;
725
726 /*
727 * Read the text and data sections and zero the bss.
728 */
729 for (i = 0; i < 2; i++) {
730 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
731 error = vn_rdwr(UIO_READ, nd.ni_vp,
732 segbase, segs[i]->p_filesz, segs[i]->p_offset,
733 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
734 &resid, td);
735 if (error) {
736 goto out;
737 }
738 bzero(segbase + segs[i]->p_filesz,
739 segs[i]->p_memsz - segs[i]->p_filesz);
740
741 #ifdef SPARSE_MAPPING
742 /*
743 * Wire down the pages
744 */
745 error = vm_map_wire(kernel_map,
746 (vm_offset_t) segbase,
747 (vm_offset_t) segbase + segs[i]->p_memsz,
748 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
749 if (error != KERN_SUCCESS) {
750 error = ENOMEM;
751 goto out;
752 }
753 #endif
754 }
755
756 #ifdef GPROF
757 /* Update profiling information with the new text segment. */
758 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
759 segs[0]->p_memsz));
760 #endif
761
762 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
763
764 lf->address = ef->address;
765 lf->size = mapsize;
766
767 error = parse_dynamic(ef);
768 if (error)
769 goto out;
770 link_elf_reloc_local(lf);
771
772 error = linker_load_dependencies(lf);
773 if (error)
774 goto out;
775 #if 0 /* this will be more trouble than it's worth for now */
776 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
777 if (dp->d_tag != DT_NEEDED)
778 continue;
779 modname = ef->strtab + dp->d_un.d_val;
780 error = linker_load_module(modname, lf);
781 if (error)
782 goto out;
783 }
784 #endif
785 error = relocate_file(ef);
786 if (error)
787 goto out;
788
789 /* Try and load the symbol table if it's present. (you can strip it!) */
790 nbytes = hdr->e_shnum * hdr->e_shentsize;
791 if (nbytes == 0 || hdr->e_shoff == 0)
792 goto nosyms;
793 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
794 if (shdr == NULL) {
795 error = ENOMEM;
796 goto out;
797 }
798 error = vn_rdwr(UIO_READ, nd.ni_vp,
799 (caddr_t)shdr, nbytes, hdr->e_shoff,
800 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
801 &resid, td);
802 if (error)
803 goto out;
804 symtabindex = -1;
805 symstrindex = -1;
806 for (i = 0; i < hdr->e_shnum; i++) {
807 if (shdr[i].sh_type == SHT_SYMTAB) {
808 symtabindex = i;
809 symstrindex = shdr[i].sh_link;
810 }
811 }
812 if (symtabindex < 0 || symstrindex < 0)
813 goto nosyms;
814
815 symcnt = shdr[symtabindex].sh_size;
816 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
817 strcnt = shdr[symstrindex].sh_size;
818 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
819
820 if (ef->symbase == NULL || ef->strbase == NULL) {
821 error = ENOMEM;
822 goto out;
823 }
824 error = vn_rdwr(UIO_READ, nd.ni_vp,
825 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
826 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
827 &resid, td);
828 if (error)
829 goto out;
830 error = vn_rdwr(UIO_READ, nd.ni_vp,
831 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
832 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
833 &resid, td);
834 if (error)
835 goto out;
836
837 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
838 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
839 ef->ddbstrcnt = strcnt;
840 ef->ddbstrtab = ef->strbase;
841
842 error = link_elf_link_common_finish(lf);
843 if (error)
844 goto out;
845
846 nosyms:
847
848 *result = lf;
849
850 out:
851 if (error && lf)
852 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
853 if (shdr)
854 free(shdr, M_LINKER);
855 if (firstpage)
856 free(firstpage, M_LINKER);
857 VOP_UNLOCK(nd.ni_vp, 0, td);
858 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
859
860 return error;
861 }
862
863 static void
864 link_elf_unload_file(linker_file_t file)
865 {
866 elf_file_t ef = (elf_file_t) file;
867
868 #ifdef GDB
869 if (ef->gdb.l_ld) {
870 GDB_STATE(RT_DELETE);
871 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
872 link_elf_delete_gdb(&ef->gdb);
873 GDB_STATE(RT_CONSISTENT);
874 }
875 #endif
876
877 /* Notify MD code that a module is being unloaded. */
878 elf_cpu_unload_file(file);
879
880 if (ef->preloaded) {
881 link_elf_unload_preload(file);
882 return;
883 }
884
885 #ifdef SPARSE_MAPPING
886 if (ef->object) {
887 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
888 (vm_offset_t) ef->address
889 + (ef->object->size << PAGE_SHIFT));
890 }
891 #else
892 if (ef->address)
893 free(ef->address, M_LINKER);
894 #endif
895 if (ef->symbase)
896 free(ef->symbase, M_LINKER);
897 if (ef->strbase)
898 free(ef->strbase, M_LINKER);
899 }
900
901 static void
902 link_elf_unload_preload(linker_file_t file)
903 {
904 if (file->filename)
905 preload_delete_name(file->filename);
906 }
907
908 static const char *
909 symbol_name(elf_file_t ef, Elf_Size r_info)
910 {
911 const Elf_Sym *ref;
912
913 if (ELF_R_SYM(r_info)) {
914 ref = ef->symtab + ELF_R_SYM(r_info);
915 return ef->strtab + ref->st_name;
916 } else
917 return NULL;
918 }
919
920 static int
921 relocate_file(elf_file_t ef)
922 {
923 const Elf_Rel *rellim;
924 const Elf_Rel *rel;
925 const Elf_Rela *relalim;
926 const Elf_Rela *rela;
927 const char *symname;
928
929 /* Perform relocations without addend if there are any: */
930 rel = ef->rel;
931 if (rel) {
932 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
933 while (rel < rellim) {
934 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
935 elf_lookup)) {
936 symname = symbol_name(ef, rel->r_info);
937 printf("link_elf: symbol %s undefined\n", symname);
938 return ENOENT;
939 }
940 rel++;
941 }
942 }
943
944 /* Perform relocations with addend if there are any: */
945 rela = ef->rela;
946 if (rela) {
947 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
948 while (rela < relalim) {
949 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
950 elf_lookup)) {
951 symname = symbol_name(ef, rela->r_info);
952 printf("link_elf: symbol %s undefined\n", symname);
953 return ENOENT;
954 }
955 rela++;
956 }
957 }
958
959 /* Perform PLT relocations without addend if there are any: */
960 rel = ef->pltrel;
961 if (rel) {
962 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
963 while (rel < rellim) {
964 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
965 elf_lookup)) {
966 symname = symbol_name(ef, rel->r_info);
967 printf("link_elf: symbol %s undefined\n", symname);
968 return ENOENT;
969 }
970 rel++;
971 }
972 }
973
974 /* Perform relocations with addend if there are any: */
975 rela = ef->pltrela;
976 if (rela) {
977 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
978 while (rela < relalim) {
979 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
980 elf_lookup)) {
981 symname = symbol_name(ef, rela->r_info);
982 printf("link_elf: symbol %s undefined\n", symname);
983 return ENOENT;
984 }
985 rela++;
986 }
987 }
988
989 return 0;
990 }
991
992 /*
993 * Hash function for symbol table lookup. Don't even think about changing
994 * this. It is specified by the System V ABI.
995 */
996 static unsigned long
997 elf_hash(const char *name)
998 {
999 const unsigned char *p = (const unsigned char *) name;
1000 unsigned long h = 0;
1001 unsigned long g;
1002
1003 while (*p != '\0') {
1004 h = (h << 4) + *p++;
1005 if ((g = h & 0xf0000000) != 0)
1006 h ^= g >> 24;
1007 h &= ~g;
1008 }
1009 return h;
1010 }
1011
1012 static int
1013 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
1014 {
1015 elf_file_t ef = (elf_file_t) lf;
1016 unsigned long symnum;
1017 const Elf_Sym* symp;
1018 const char *strp;
1019 unsigned long hash;
1020 int i;
1021
1022 /* If we don't have a hash, bail. */
1023 if (ef->buckets == NULL || ef->nbuckets == 0) {
1024 printf("link_elf_lookup_symbol: missing symbol hash table\n");
1025 return ENOENT;
1026 }
1027
1028 /* First, search hashed global symbols */
1029 hash = elf_hash(name);
1030 symnum = ef->buckets[hash % ef->nbuckets];
1031
1032 while (symnum != STN_UNDEF) {
1033 if (symnum >= ef->nchains) {
1034 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1035 return ENOENT;
1036 }
1037
1038 symp = ef->symtab + symnum;
1039 if (symp->st_name == 0) {
1040 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1041 return ENOENT;
1042 }
1043
1044 strp = ef->strtab + symp->st_name;
1045
1046 if (strcmp(name, strp) == 0) {
1047 if (symp->st_shndx != SHN_UNDEF ||
1048 (symp->st_value != 0 &&
1049 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1050 *sym = (c_linker_sym_t) symp;
1051 return 0;
1052 } else
1053 return ENOENT;
1054 }
1055
1056 symnum = ef->chains[symnum];
1057 }
1058
1059 /* If we have not found it, look at the full table (if loaded) */
1060 if (ef->symtab == ef->ddbsymtab)
1061 return ENOENT;
1062
1063 /* Exhaustive search */
1064 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1065 strp = ef->ddbstrtab + symp->st_name;
1066 if (strcmp(name, strp) == 0) {
1067 if (symp->st_shndx != SHN_UNDEF ||
1068 (symp->st_value != 0 &&
1069 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1070 *sym = (c_linker_sym_t) symp;
1071 return 0;
1072 } else
1073 return ENOENT;
1074 }
1075 }
1076
1077 return ENOENT;
1078 }
1079
1080 static int
1081 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1082 {
1083 elf_file_t ef = (elf_file_t) lf;
1084 const Elf_Sym* es = (const Elf_Sym*) sym;
1085
1086 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1087 symval->name = ef->strtab + es->st_name;
1088 symval->value = (caddr_t) ef->address + es->st_value;
1089 symval->size = es->st_size;
1090 return 0;
1091 }
1092 if (ef->symtab == ef->ddbsymtab)
1093 return ENOENT;
1094 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1095 symval->name = ef->ddbstrtab + es->st_name;
1096 symval->value = (caddr_t) ef->address + es->st_value;
1097 symval->size = es->st_size;
1098 return 0;
1099 }
1100 return ENOENT;
1101 }
1102
1103 static int
1104 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1105 c_linker_sym_t* sym, long* diffp)
1106 {
1107 elf_file_t ef = (elf_file_t) lf;
1108 u_long off = (uintptr_t) (void *) value;
1109 u_long diff = off;
1110 u_long st_value;
1111 const Elf_Sym* es;
1112 const Elf_Sym* best = 0;
1113 int i;
1114
1115 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1116 if (es->st_name == 0)
1117 continue;
1118 st_value = es->st_value + (uintptr_t) (void *) ef->address;
1119 if (off >= st_value) {
1120 if (off - st_value < diff) {
1121 diff = off - st_value;
1122 best = es;
1123 if (diff == 0)
1124 break;
1125 } else if (off - st_value == diff) {
1126 best = es;
1127 }
1128 }
1129 }
1130 if (best == 0)
1131 *diffp = off;
1132 else
1133 *diffp = diff;
1134 *sym = (c_linker_sym_t) best;
1135
1136 return 0;
1137 }
1138
1139 /*
1140 * Look up a linker set on an ELF system.
1141 */
1142 static int
1143 link_elf_lookup_set(linker_file_t lf, const char *name,
1144 void ***startp, void ***stopp, int *countp)
1145 {
1146 c_linker_sym_t sym;
1147 linker_symval_t symval;
1148 char *setsym;
1149 void **start, **stop;
1150 int len, error = 0, count;
1151
1152 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1153 setsym = malloc(len, M_LINKER, M_WAITOK);
1154 if (setsym == NULL)
1155 return ENOMEM;
1156
1157 /* get address of first entry */
1158 snprintf(setsym, len, "%s%s", "__start_set_", name);
1159 error = link_elf_lookup_symbol(lf, setsym, &sym);
1160 if (error)
1161 goto out;
1162 link_elf_symbol_values(lf, sym, &symval);
1163 if (symval.value == 0) {
1164 error = ESRCH;
1165 goto out;
1166 }
1167 start = (void **)symval.value;
1168
1169 /* get address of last entry */
1170 snprintf(setsym, len, "%s%s", "__stop_set_", name);
1171 error = link_elf_lookup_symbol(lf, setsym, &sym);
1172 if (error)
1173 goto out;
1174 link_elf_symbol_values(lf, sym, &symval);
1175 if (symval.value == 0) {
1176 error = ESRCH;
1177 goto out;
1178 }
1179 stop = (void **)symval.value;
1180
1181 /* and the number of entries */
1182 count = stop - start;
1183
1184 /* and copy out */
1185 if (startp)
1186 *startp = start;
1187 if (stopp)
1188 *stopp = stop;
1189 if (countp)
1190 *countp = count;
1191
1192 out:
1193 free(setsym, M_LINKER);
1194 return error;
1195 }
1196
1197 static int
1198 link_elf_each_function_name(linker_file_t file,
1199 int (*callback)(const char *, void *), void *opaque) {
1200 elf_file_t ef = (elf_file_t)file;
1201 const Elf_Sym* symp;
1202 int i, error;
1203
1204 /* Exhaustive search */
1205 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1206 if (symp->st_value != 0 &&
1207 ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1208 error = callback(ef->ddbstrtab + symp->st_name, opaque);
1209 if (error)
1210 return (error);
1211 }
1212 }
1213 return (0);
1214 }
1215
1216 #ifdef __ia64__
1217 /*
1218 * Each KLD has its own GP. The GP value for each load module is given by
1219 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
1220 * don't have direct access to the ELF file structure. The link_elf_get_gp()
1221 * function returns the GP given a pointer to a generic linker file struct.
1222 */
1223 Elf_Addr
1224 link_elf_get_gp(linker_file_t lf)
1225 {
1226 elf_file_t ef = (elf_file_t)lf;
1227 return (Elf_Addr)ef->got;
1228 }
1229 #endif
1230
1231 const Elf_Sym *
1232 elf_get_sym(linker_file_t lf, Elf_Size symidx)
1233 {
1234 elf_file_t ef = (elf_file_t)lf;
1235
1236 if (symidx >= ef->nchains)
1237 return (NULL);
1238 return (ef->symtab + symidx);
1239 }
1240
1241 const char *
1242 elf_get_symname(linker_file_t lf, Elf_Size symidx)
1243 {
1244 elf_file_t ef = (elf_file_t)lf;
1245 const Elf_Sym *sym;
1246
1247 if (symidx >= ef->nchains)
1248 return (NULL);
1249 sym = ef->symtab + symidx;
1250 return (ef->strtab + sym->st_name);
1251 }
1252
1253 /*
1254 * Symbol lookup function that can be used when the symbol index is known (ie
1255 * in relocations). It uses the symbol index instead of doing a fully fledged
1256 * hash table based lookup when such is valid. For example for local symbols.
1257 * This is not only more efficient, it's also more correct. It's not always
1258 * the case that the symbol can be found through the hash table.
1259 */
1260 static Elf_Addr
1261 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
1262 {
1263 elf_file_t ef = (elf_file_t)lf;
1264 const Elf_Sym *sym;
1265 const char *symbol;
1266
1267 /* Don't even try to lookup the symbol if the index is bogus. */
1268 if (symidx >= ef->nchains)
1269 return (0);
1270
1271 sym = ef->symtab + symidx;
1272
1273 /*
1274 * Don't do a full lookup when the symbol is local. It may even
1275 * fail because it may not be found through the hash table.
1276 */
1277 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1278 /* Force lookup failure when we have an insanity. */
1279 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1280 return (0);
1281 return ((Elf_Addr)ef->address + sym->st_value);
1282 }
1283
1284 /*
1285 * XXX we can avoid doing a hash table based lookup for global
1286 * symbols as well. This however is not always valid, so we'll
1287 * just do it the hard way for now. Performance tweaks can
1288 * always be added.
1289 */
1290
1291 symbol = ef->strtab + sym->st_name;
1292
1293 /* Force a lookup failure if the symbol name is bogus. */
1294 if (*symbol == 0)
1295 return (0);
1296
1297 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1298 }
1299
1300 static void
1301 link_elf_reloc_local(linker_file_t lf)
1302 {
1303 const Elf_Rel *rellim;
1304 const Elf_Rel *rel;
1305 const Elf_Rela *relalim;
1306 const Elf_Rela *rela;
1307 elf_file_t ef = (elf_file_t)lf;
1308
1309 /* Perform relocations without addend if there are any: */
1310 if ((rel = ef->rel) != NULL) {
1311 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1312 while (rel < rellim) {
1313 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
1314 elf_lookup);
1315 rel++;
1316 }
1317 }
1318
1319 /* Perform relocations with addend if there are any: */
1320 if ((rela = ef->rela) != NULL) {
1321 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
1322 while (rela < relalim) {
1323 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
1324 elf_lookup);
1325 rela++;
1326 }
1327 }
1328 }
Cache object: 731d38ab4e0da0ccf77f3bb66579ed31
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