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/6.3/sys/kern/link_elf.c 173886 2007-11-24 19:45:58Z 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 #define MAXSEGS 4
66
67 typedef struct elf_file {
68 struct linker_file lf; /* Common fields */
69 int preloaded; /* Was file pre-loaded */
70 caddr_t address; /* Relocation address */
71 #ifdef SPARSE_MAPPING
72 vm_object_t object; /* VM object to hold file pages */
73 #endif
74 Elf_Dyn* dynamic; /* Symbol table etc. */
75 Elf_Hashelt nbuckets; /* DT_HASH info */
76 Elf_Hashelt nchains;
77 const Elf_Hashelt* buckets;
78 const Elf_Hashelt* chains;
79 caddr_t hash;
80 caddr_t strtab; /* DT_STRTAB */
81 int strsz; /* DT_STRSZ */
82 const Elf_Sym* symtab; /* DT_SYMTAB */
83 Elf_Addr* got; /* DT_PLTGOT */
84 const Elf_Rel* pltrel; /* DT_JMPREL */
85 int pltrelsize; /* DT_PLTRELSZ */
86 const Elf_Rela* pltrela; /* DT_JMPREL */
87 int pltrelasize; /* DT_PLTRELSZ */
88 const Elf_Rel* rel; /* DT_REL */
89 int relsize; /* DT_RELSZ */
90 const Elf_Rela* rela; /* DT_RELA */
91 int relasize; /* DT_RELASZ */
92 caddr_t modptr;
93 const Elf_Sym* ddbsymtab; /* The symbol table we are using */
94 long ddbsymcnt; /* Number of symbols */
95 caddr_t ddbstrtab; /* String table */
96 long ddbstrcnt; /* number of bytes in string table */
97 caddr_t symbase; /* malloc'ed symbold base */
98 caddr_t strbase; /* malloc'ed string base */
99 #ifdef GDB
100 struct link_map gdb; /* hooks for gdb */
101 #endif
102 } *elf_file_t;
103
104 static int link_elf_link_common_finish(linker_file_t);
105 static int link_elf_link_preload(linker_class_t cls,
106 const char*, linker_file_t*);
107 static int link_elf_link_preload_finish(linker_file_t);
108 static int link_elf_load_file(linker_class_t, const char*, linker_file_t*);
109 static int link_elf_lookup_symbol(linker_file_t, const char*,
110 c_linker_sym_t*);
111 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
112 static int link_elf_search_symbol(linker_file_t, caddr_t value,
113 c_linker_sym_t* sym, long* diffp);
114
115 static void link_elf_unload_file(linker_file_t);
116 static void link_elf_unload_preload(linker_file_t);
117 static int link_elf_lookup_set(linker_file_t, const char *,
118 void ***, void ***, int *);
119 static int link_elf_each_function_name(linker_file_t,
120 int (*)(const char *, void *),
121 void *);
122 static void link_elf_reloc_local(linker_file_t);
123 static Elf_Addr elf_lookup(linker_file_t lf, Elf_Size symidx, int deps);
124
125 static kobj_method_t link_elf_methods[] = {
126 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
127 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
128 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
129 KOBJMETHOD(linker_unload, link_elf_unload_file),
130 KOBJMETHOD(linker_load_file, link_elf_load_file),
131 KOBJMETHOD(linker_link_preload, link_elf_link_preload),
132 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
133 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set),
134 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
135 { 0, 0 }
136 };
137
138 static struct linker_class link_elf_class = {
139 #if ELF_TARG_CLASS == ELFCLASS32
140 "elf32",
141 #else
142 "elf64",
143 #endif
144 link_elf_methods, sizeof(struct elf_file)
145 };
146
147 static int parse_dynamic(elf_file_t ef);
148 static int relocate_file(elf_file_t ef);
149 static int link_elf_preload_parse_symbols(elf_file_t ef);
150
151 #ifdef GDB
152 static void r_debug_state(struct r_debug *dummy_one,
153 struct link_map *dummy_two);
154
155 /*
156 * A list of loaded modules for GDB to use for loading symbols.
157 */
158 struct r_debug r_debug;
159
160 #define GDB_STATE(s) r_debug.r_state = s; r_debug_state(NULL, NULL);
161
162 /*
163 * Function for the debugger to set a breakpoint on to gain control.
164 */
165 static void
166 r_debug_state(struct r_debug *dummy_one __unused,
167 struct link_map *dummy_two __unused)
168 {
169 }
170
171 static void
172 link_elf_add_gdb(struct link_map *l)
173 {
174 struct link_map *prev;
175
176 l->l_next = NULL;
177
178 if (r_debug.r_map == NULL) {
179 /* Add first. */
180 l->l_prev = NULL;
181 r_debug.r_map = l;
182 } else {
183 /* Append to list. */
184 for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
185 ;
186 l->l_prev = prev;
187 prev->l_next = l;
188 }
189 }
190
191 static void
192 link_elf_delete_gdb(struct link_map *l)
193 {
194 if (l->l_prev == NULL) {
195 /* Remove first. */
196 if ((r_debug.r_map = l->l_next) != NULL)
197 l->l_next->l_prev = NULL;
198 } else {
199 /* Remove any but first. */
200 if ((l->l_prev->l_next = l->l_next) != NULL)
201 l->l_next->l_prev = l->l_prev;
202 }
203 }
204 #endif /* GDB */
205
206 #ifdef __ia64__
207 Elf_Addr link_elf_get_gp(linker_file_t);
208 #endif
209
210 /*
211 * The kernel symbol table starts here.
212 */
213 extern struct _dynamic _DYNAMIC;
214
215 static void
216 link_elf_error(const char *s)
217 {
218 printf("kldload: %s\n", s);
219 }
220
221 /*
222 * Actions performed after linking/loading both the preloaded kernel and any
223 * modules; whether preloaded or dynamicly loaded.
224 */
225 static int
226 link_elf_link_common_finish(linker_file_t lf)
227 {
228 #ifdef GDB
229 elf_file_t ef = (elf_file_t)lf;
230 char *newfilename;
231 #endif
232 int error;
233
234 /* Notify MD code that a module is being loaded. */
235 error = elf_cpu_load_file(lf);
236 if (error)
237 return (error);
238
239 #ifdef GDB
240 GDB_STATE(RT_ADD);
241 ef->gdb.l_addr = lf->address;
242 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
243 strcpy(newfilename, lf->filename);
244 ef->gdb.l_name = newfilename;
245 ef->gdb.l_ld = ef->dynamic;
246 link_elf_add_gdb(&ef->gdb);
247 GDB_STATE(RT_CONSISTENT);
248 #endif
249
250 return (0);
251 }
252
253 static void
254 link_elf_init(void* arg)
255 {
256 Elf_Dyn *dp;
257 caddr_t modptr, baseptr, sizeptr;
258 elf_file_t ef;
259 char *modname;
260
261 linker_add_class(&link_elf_class);
262
263 dp = (Elf_Dyn*) &_DYNAMIC;
264 modname = NULL;
265 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
266 if (modptr == NULL)
267 modptr = preload_search_by_type("elf kernel");
268 if (modptr)
269 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
270 if (modname == NULL)
271 modname = "kernel";
272 linker_kernel_file = linker_make_file(modname, &link_elf_class);
273 if (linker_kernel_file == NULL)
274 panic("link_elf_init: Can't create linker structures for kernel");
275
276 ef = (elf_file_t) linker_kernel_file;
277 ef->preloaded = 1;
278 ef->address = 0;
279 #ifdef SPARSE_MAPPING
280 ef->object = 0;
281 #endif
282 ef->dynamic = dp;
283
284 if (dp)
285 parse_dynamic(ef);
286 linker_kernel_file->address = (caddr_t) KERNBASE;
287 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
288
289 if (modptr) {
290 ef->modptr = modptr;
291 baseptr = preload_search_info(modptr, MODINFO_ADDR);
292 if (baseptr)
293 linker_kernel_file->address = *(caddr_t *)baseptr;
294 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
295 if (sizeptr)
296 linker_kernel_file->size = *(size_t *)sizeptr;
297 }
298 (void)link_elf_preload_parse_symbols(ef);
299
300 #ifdef GDB
301 r_debug.r_map = NULL;
302 r_debug.r_brk = r_debug_state;
303 r_debug.r_state = RT_CONSISTENT;
304 #endif
305
306 (void)link_elf_link_common_finish(linker_kernel_file);
307 }
308
309 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
310
311 static int
312 link_elf_preload_parse_symbols(elf_file_t ef)
313 {
314 caddr_t pointer;
315 caddr_t ssym, esym, base;
316 caddr_t strtab;
317 int strcnt;
318 Elf_Sym* symtab;
319 int symcnt;
320
321 if (ef->modptr == NULL)
322 return 0;
323 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
324 if (pointer == NULL)
325 return 0;
326 ssym = *(caddr_t *)pointer;
327 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
328 if (pointer == NULL)
329 return 0;
330 esym = *(caddr_t *)pointer;
331
332 base = ssym;
333
334 symcnt = *(long *)base;
335 base += sizeof(long);
336 symtab = (Elf_Sym *)base;
337 base += roundup(symcnt, sizeof(long));
338
339 if (base > esym || base < ssym) {
340 printf("Symbols are corrupt!\n");
341 return EINVAL;
342 }
343
344 strcnt = *(long *)base;
345 base += sizeof(long);
346 strtab = base;
347 base += roundup(strcnt, sizeof(long));
348
349 if (base > esym || base < ssym) {
350 printf("Symbols are corrupt!\n");
351 return EINVAL;
352 }
353
354 ef->ddbsymtab = symtab;
355 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
356 ef->ddbstrtab = strtab;
357 ef->ddbstrcnt = strcnt;
358
359 return 0;
360 }
361
362 static int
363 parse_dynamic(elf_file_t ef)
364 {
365 Elf_Dyn *dp;
366 int plttype = DT_REL;
367
368 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
369 switch (dp->d_tag) {
370 case DT_HASH:
371 {
372 /* From src/libexec/rtld-elf/rtld.c */
373 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
374 (ef->address + dp->d_un.d_ptr);
375 ef->nbuckets = hashtab[0];
376 ef->nchains = hashtab[1];
377 ef->buckets = hashtab + 2;
378 ef->chains = ef->buckets + ef->nbuckets;
379 break;
380 }
381 case DT_STRTAB:
382 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
383 break;
384 case DT_STRSZ:
385 ef->strsz = dp->d_un.d_val;
386 break;
387 case DT_SYMTAB:
388 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
389 break;
390 case DT_SYMENT:
391 if (dp->d_un.d_val != sizeof(Elf_Sym))
392 return ENOEXEC;
393 break;
394 case DT_PLTGOT:
395 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
396 break;
397 case DT_REL:
398 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
399 break;
400 case DT_RELSZ:
401 ef->relsize = dp->d_un.d_val;
402 break;
403 case DT_RELENT:
404 if (dp->d_un.d_val != sizeof(Elf_Rel))
405 return ENOEXEC;
406 break;
407 case DT_JMPREL:
408 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
409 break;
410 case DT_PLTRELSZ:
411 ef->pltrelsize = dp->d_un.d_val;
412 break;
413 case DT_RELA:
414 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
415 break;
416 case DT_RELASZ:
417 ef->relasize = dp->d_un.d_val;
418 break;
419 case DT_RELAENT:
420 if (dp->d_un.d_val != sizeof(Elf_Rela))
421 return ENOEXEC;
422 break;
423 case DT_PLTREL:
424 plttype = dp->d_un.d_val;
425 if (plttype != DT_REL && plttype != DT_RELA)
426 return ENOEXEC;
427 break;
428 #ifdef GDB
429 case DT_DEBUG:
430 dp->d_un.d_ptr = (Elf_Addr) &r_debug;
431 break;
432 #endif
433 }
434 }
435
436 if (plttype == DT_RELA) {
437 ef->pltrela = (const Elf_Rela *) ef->pltrel;
438 ef->pltrel = NULL;
439 ef->pltrelasize = ef->pltrelsize;
440 ef->pltrelsize = 0;
441 }
442
443 ef->ddbsymtab = ef->symtab;
444 ef->ddbsymcnt = ef->nchains;
445 ef->ddbstrtab = ef->strtab;
446 ef->ddbstrcnt = ef->strsz;
447
448 return 0;
449 }
450
451 static int
452 link_elf_link_preload(linker_class_t cls,
453 const char* filename, linker_file_t *result)
454 {
455 caddr_t modptr, baseptr, sizeptr, dynptr;
456 char *type;
457 elf_file_t ef;
458 linker_file_t lf;
459 int error;
460 vm_offset_t dp;
461
462 /* Look to see if we have the file preloaded */
463 modptr = preload_search_by_name(filename);
464 if (modptr == NULL)
465 return ENOENT;
466
467 type = (char *)preload_search_info(modptr, MODINFO_TYPE);
468 baseptr = preload_search_info(modptr, MODINFO_ADDR);
469 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
470 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
471 if (type == NULL ||
472 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
473 strcmp(type, "elf module") != 0))
474 return (EFTYPE);
475 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
476 return (EINVAL);
477
478 lf = linker_make_file(filename, &link_elf_class);
479 if (lf == NULL) {
480 return ENOMEM;
481 }
482
483 ef = (elf_file_t) lf;
484 ef->preloaded = 1;
485 ef->modptr = modptr;
486 ef->address = *(caddr_t *)baseptr;
487 #ifdef SPARSE_MAPPING
488 ef->object = 0;
489 #endif
490 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
491 ef->dynamic = (Elf_Dyn *)dp;
492 lf->address = ef->address;
493 lf->size = *(size_t *)sizeptr;
494
495 error = parse_dynamic(ef);
496 if (error) {
497 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
498 return error;
499 }
500 link_elf_reloc_local(lf);
501 *result = lf;
502 return (0);
503 }
504
505 static int
506 link_elf_link_preload_finish(linker_file_t lf)
507 {
508 elf_file_t ef;
509 int error;
510
511 ef = (elf_file_t) lf;
512 #if 0 /* this will be more trouble than it's worth for now */
513 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
514 if (dp->d_tag != DT_NEEDED)
515 continue;
516 modname = ef->strtab + dp->d_un.d_val;
517 error = linker_load_module(modname, lf);
518 if (error)
519 goto out;
520 }
521 #endif
522 error = relocate_file(ef);
523 if (error)
524 return error;
525 (void)link_elf_preload_parse_symbols(ef);
526
527 return (link_elf_link_common_finish(lf));
528 }
529
530 static int
531 link_elf_load_file(linker_class_t cls, const char* filename,
532 linker_file_t* result)
533 {
534 struct nameidata nd;
535 struct thread* td = curthread; /* XXX */
536 Elf_Ehdr *hdr;
537 caddr_t firstpage;
538 int nbytes, i;
539 Elf_Phdr *phdr;
540 Elf_Phdr *phlimit;
541 Elf_Phdr *segs[MAXSEGS];
542 int nsegs;
543 Elf_Phdr *phdyn;
544 Elf_Phdr *phphdr;
545 caddr_t mapbase;
546 size_t mapsize;
547 Elf_Off base_offset;
548 Elf_Addr base_vaddr;
549 Elf_Addr base_vlimit;
550 int error = 0;
551 int resid, flags;
552 elf_file_t ef;
553 linker_file_t lf;
554 Elf_Shdr *shdr;
555 int symtabindex;
556 int symstrindex;
557 int symcnt;
558 int strcnt;
559
560 GIANT_REQUIRED;
561
562 shdr = NULL;
563 lf = NULL;
564
565 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
566 flags = FREAD;
567 error = vn_open(&nd, &flags, 0, -1);
568 if (error)
569 return error;
570 NDFREE(&nd, NDF_ONLY_PNBUF);
571 #ifdef MAC
572 error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp);
573 if (error) {
574 firstpage = NULL;
575 goto out;
576 }
577 #endif
578
579 /*
580 * Read the elf header from the file.
581 */
582 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
583 if (firstpage == NULL) {
584 error = ENOMEM;
585 goto out;
586 }
587 hdr = (Elf_Ehdr *)firstpage;
588 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
589 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
590 &resid, td);
591 nbytes = PAGE_SIZE - resid;
592 if (error)
593 goto out;
594
595 if (!IS_ELF(*hdr)) {
596 error = ENOEXEC;
597 goto out;
598 }
599
600 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
601 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
602 link_elf_error("Unsupported file layout");
603 error = ENOEXEC;
604 goto out;
605 }
606 if (hdr->e_ident[EI_VERSION] != EV_CURRENT
607 || hdr->e_version != EV_CURRENT) {
608 link_elf_error("Unsupported file version");
609 error = ENOEXEC;
610 goto out;
611 }
612 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
613 link_elf_error("Unsupported file type");
614 error = ENOEXEC;
615 goto out;
616 }
617 if (hdr->e_machine != ELF_TARG_MACH) {
618 link_elf_error("Unsupported machine");
619 error = ENOEXEC;
620 goto out;
621 }
622
623 /*
624 * We rely on the program header being in the first page. This is
625 * not strictly required by the ABI specification, but it seems to
626 * always true in practice. And, it simplifies things considerably.
627 */
628 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
629 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
630 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
631 link_elf_error("Unreadable program headers");
632
633 /*
634 * Scan the program header entries, and save key information.
635 *
636 * We rely on there being exactly two load segments, text and data,
637 * in that order.
638 */
639 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
640 phlimit = phdr + hdr->e_phnum;
641 nsegs = 0;
642 phdyn = NULL;
643 phphdr = NULL;
644 while (phdr < phlimit) {
645 switch (phdr->p_type) {
646
647 case PT_LOAD:
648 if (nsegs == MAXSEGS) {
649 link_elf_error("Too many sections");
650 error = ENOEXEC;
651 goto out;
652 }
653 /*
654 * XXX: We just trust they come in right order ??
655 */
656 segs[nsegs] = phdr;
657 ++nsegs;
658 break;
659
660 case PT_PHDR:
661 phphdr = phdr;
662 break;
663
664 case PT_DYNAMIC:
665 phdyn = phdr;
666 break;
667
668 case PT_INTERP:
669 link_elf_error("Unsupported file type");
670 error = ENOEXEC;
671 goto out;
672 }
673
674 ++phdr;
675 }
676 if (phdyn == NULL) {
677 link_elf_error("Object is not dynamically-linked");
678 error = ENOEXEC;
679 goto out;
680 }
681 if (nsegs == 0) {
682 link_elf_error("No sections");
683 error = ENOEXEC;
684 goto out;
685 }
686
687 /*
688 * Allocate the entire address space of the object, to stake out our
689 * contiguous region, and to establish the base address for relocation.
690 */
691 base_offset = trunc_page(segs[0]->p_offset);
692 base_vaddr = trunc_page(segs[0]->p_vaddr);
693 base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
694 segs[nsegs - 1]->p_memsz);
695 mapsize = base_vlimit - base_vaddr;
696
697 lf = linker_make_file(filename, &link_elf_class);
698 if (!lf) {
699 error = ENOMEM;
700 goto out;
701 }
702
703 ef = (elf_file_t) lf;
704 #ifdef SPARSE_MAPPING
705 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
706 if (ef->object == NULL) {
707 error = ENOMEM;
708 goto out;
709 }
710 ef->address = (caddr_t) vm_map_min(kernel_map);
711 error = vm_map_find(kernel_map, ef->object, 0,
712 (vm_offset_t *) &ef->address,
713 mapsize, 1,
714 VM_PROT_ALL, VM_PROT_ALL, 0);
715 if (error) {
716 vm_object_deallocate(ef->object);
717 ef->object = 0;
718 goto out;
719 }
720 #else
721 ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
722 if (!ef->address) {
723 error = ENOMEM;
724 goto out;
725 }
726 #endif
727 mapbase = ef->address;
728
729 /*
730 * Read the text and data sections and zero the bss.
731 */
732 for (i = 0; i < nsegs; i++) {
733 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
734 error = vn_rdwr(UIO_READ, nd.ni_vp,
735 segbase, segs[i]->p_filesz, segs[i]->p_offset,
736 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
737 &resid, td);
738 if (error) {
739 goto out;
740 }
741 bzero(segbase + segs[i]->p_filesz,
742 segs[i]->p_memsz - segs[i]->p_filesz);
743
744 #ifdef SPARSE_MAPPING
745 /*
746 * Wire down the pages
747 */
748 error = vm_map_wire(kernel_map,
749 (vm_offset_t) segbase,
750 (vm_offset_t) segbase + segs[i]->p_memsz,
751 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
752 if (error != KERN_SUCCESS) {
753 error = ENOMEM;
754 goto out;
755 }
756 #endif
757 }
758
759 #ifdef GPROF
760 /* Update profiling information with the new text segment. */
761 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
762 segs[0]->p_memsz));
763 #endif
764
765 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
766
767 lf->address = ef->address;
768 lf->size = mapsize;
769
770 error = parse_dynamic(ef);
771 if (error)
772 goto out;
773 link_elf_reloc_local(lf);
774
775 error = linker_load_dependencies(lf);
776 if (error)
777 goto out;
778 #if 0 /* this will be more trouble than it's worth for now */
779 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
780 if (dp->d_tag != DT_NEEDED)
781 continue;
782 modname = ef->strtab + dp->d_un.d_val;
783 error = linker_load_module(modname, lf);
784 if (error)
785 goto out;
786 }
787 #endif
788 error = relocate_file(ef);
789 if (error)
790 goto out;
791
792 /* Try and load the symbol table if it's present. (you can strip it!) */
793 nbytes = hdr->e_shnum * hdr->e_shentsize;
794 if (nbytes == 0 || hdr->e_shoff == 0)
795 goto nosyms;
796 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
797 if (shdr == NULL) {
798 error = ENOMEM;
799 goto out;
800 }
801 error = vn_rdwr(UIO_READ, nd.ni_vp,
802 (caddr_t)shdr, nbytes, hdr->e_shoff,
803 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
804 &resid, td);
805 if (error)
806 goto out;
807 symtabindex = -1;
808 symstrindex = -1;
809 for (i = 0; i < hdr->e_shnum; i++) {
810 if (shdr[i].sh_type == SHT_SYMTAB) {
811 symtabindex = i;
812 symstrindex = shdr[i].sh_link;
813 }
814 }
815 if (symtabindex < 0 || symstrindex < 0)
816 goto nosyms;
817
818 symcnt = shdr[symtabindex].sh_size;
819 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
820 strcnt = shdr[symstrindex].sh_size;
821 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
822
823 if (ef->symbase == NULL || ef->strbase == NULL) {
824 error = ENOMEM;
825 goto out;
826 }
827 error = vn_rdwr(UIO_READ, nd.ni_vp,
828 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
829 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
830 &resid, td);
831 if (error)
832 goto out;
833 error = vn_rdwr(UIO_READ, nd.ni_vp,
834 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
835 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
836 &resid, td);
837 if (error)
838 goto out;
839
840 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
841 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
842 ef->ddbstrcnt = strcnt;
843 ef->ddbstrtab = ef->strbase;
844
845 error = link_elf_link_common_finish(lf);
846 if (error)
847 goto out;
848
849 nosyms:
850
851 *result = lf;
852
853 out:
854 if (error && lf)
855 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
856 if (shdr)
857 free(shdr, M_LINKER);
858 if (firstpage)
859 free(firstpage, M_LINKER);
860 VOP_UNLOCK(nd.ni_vp, 0, td);
861 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
862
863 return error;
864 }
865
866 static void
867 link_elf_unload_file(linker_file_t file)
868 {
869 elf_file_t ef = (elf_file_t) file;
870
871 #ifdef GDB
872 if (ef->gdb.l_ld) {
873 GDB_STATE(RT_DELETE);
874 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
875 link_elf_delete_gdb(&ef->gdb);
876 GDB_STATE(RT_CONSISTENT);
877 }
878 #endif
879
880 /* Notify MD code that a module is being unloaded. */
881 elf_cpu_unload_file(file);
882
883 if (ef->preloaded) {
884 link_elf_unload_preload(file);
885 return;
886 }
887
888 #ifdef SPARSE_MAPPING
889 if (ef->object) {
890 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
891 (vm_offset_t) ef->address
892 + (ef->object->size << PAGE_SHIFT));
893 }
894 #else
895 if (ef->address)
896 free(ef->address, M_LINKER);
897 #endif
898 if (ef->symbase)
899 free(ef->symbase, M_LINKER);
900 if (ef->strbase)
901 free(ef->strbase, M_LINKER);
902 }
903
904 static void
905 link_elf_unload_preload(linker_file_t file)
906 {
907 if (file->filename)
908 preload_delete_name(file->filename);
909 }
910
911 static const char *
912 symbol_name(elf_file_t ef, Elf_Size r_info)
913 {
914 const Elf_Sym *ref;
915
916 if (ELF_R_SYM(r_info)) {
917 ref = ef->symtab + ELF_R_SYM(r_info);
918 return ef->strtab + ref->st_name;
919 } else
920 return NULL;
921 }
922
923 static int
924 relocate_file(elf_file_t ef)
925 {
926 const Elf_Rel *rellim;
927 const Elf_Rel *rel;
928 const Elf_Rela *relalim;
929 const Elf_Rela *rela;
930 const char *symname;
931
932 /* Perform relocations without addend if there are any: */
933 rel = ef->rel;
934 if (rel) {
935 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
936 while (rel < rellim) {
937 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
938 elf_lookup)) {
939 symname = symbol_name(ef, rel->r_info);
940 printf("link_elf: symbol %s undefined\n", symname);
941 return ENOENT;
942 }
943 rel++;
944 }
945 }
946
947 /* Perform relocations with addend if there are any: */
948 rela = ef->rela;
949 if (rela) {
950 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
951 while (rela < relalim) {
952 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
953 elf_lookup)) {
954 symname = symbol_name(ef, rela->r_info);
955 printf("link_elf: symbol %s undefined\n", symname);
956 return ENOENT;
957 }
958 rela++;
959 }
960 }
961
962 /* Perform PLT relocations without addend if there are any: */
963 rel = ef->pltrel;
964 if (rel) {
965 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
966 while (rel < rellim) {
967 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
968 elf_lookup)) {
969 symname = symbol_name(ef, rel->r_info);
970 printf("link_elf: symbol %s undefined\n", symname);
971 return ENOENT;
972 }
973 rel++;
974 }
975 }
976
977 /* Perform relocations with addend if there are any: */
978 rela = ef->pltrela;
979 if (rela) {
980 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
981 while (rela < relalim) {
982 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
983 elf_lookup)) {
984 symname = symbol_name(ef, rela->r_info);
985 printf("link_elf: symbol %s undefined\n", symname);
986 return ENOENT;
987 }
988 rela++;
989 }
990 }
991
992 return 0;
993 }
994
995 /*
996 * Hash function for symbol table lookup. Don't even think about changing
997 * this. It is specified by the System V ABI.
998 */
999 static unsigned long
1000 elf_hash(const char *name)
1001 {
1002 const unsigned char *p = (const unsigned char *) name;
1003 unsigned long h = 0;
1004 unsigned long g;
1005
1006 while (*p != '\0') {
1007 h = (h << 4) + *p++;
1008 if ((g = h & 0xf0000000) != 0)
1009 h ^= g >> 24;
1010 h &= ~g;
1011 }
1012 return h;
1013 }
1014
1015 static int
1016 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
1017 {
1018 elf_file_t ef = (elf_file_t) lf;
1019 unsigned long symnum;
1020 const Elf_Sym* symp;
1021 const char *strp;
1022 unsigned long hash;
1023 int i;
1024
1025 /* If we don't have a hash, bail. */
1026 if (ef->buckets == NULL || ef->nbuckets == 0) {
1027 printf("link_elf_lookup_symbol: missing symbol hash table\n");
1028 return ENOENT;
1029 }
1030
1031 /* First, search hashed global symbols */
1032 hash = elf_hash(name);
1033 symnum = ef->buckets[hash % ef->nbuckets];
1034
1035 while (symnum != STN_UNDEF) {
1036 if (symnum >= ef->nchains) {
1037 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1038 return ENOENT;
1039 }
1040
1041 symp = ef->symtab + symnum;
1042 if (symp->st_name == 0) {
1043 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1044 return ENOENT;
1045 }
1046
1047 strp = ef->strtab + symp->st_name;
1048
1049 if (strcmp(name, strp) == 0) {
1050 if (symp->st_shndx != SHN_UNDEF ||
1051 (symp->st_value != 0 &&
1052 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1053 *sym = (c_linker_sym_t) symp;
1054 return 0;
1055 } else
1056 return ENOENT;
1057 }
1058
1059 symnum = ef->chains[symnum];
1060 }
1061
1062 /* If we have not found it, look at the full table (if loaded) */
1063 if (ef->symtab == ef->ddbsymtab)
1064 return ENOENT;
1065
1066 /* Exhaustive search */
1067 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1068 strp = ef->ddbstrtab + symp->st_name;
1069 if (strcmp(name, strp) == 0) {
1070 if (symp->st_shndx != SHN_UNDEF ||
1071 (symp->st_value != 0 &&
1072 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1073 *sym = (c_linker_sym_t) symp;
1074 return 0;
1075 } else
1076 return ENOENT;
1077 }
1078 }
1079
1080 return ENOENT;
1081 }
1082
1083 static int
1084 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1085 {
1086 elf_file_t ef = (elf_file_t) lf;
1087 const Elf_Sym* es = (const Elf_Sym*) sym;
1088
1089 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1090 symval->name = ef->strtab + es->st_name;
1091 symval->value = (caddr_t) ef->address + es->st_value;
1092 symval->size = es->st_size;
1093 return 0;
1094 }
1095 if (ef->symtab == ef->ddbsymtab)
1096 return ENOENT;
1097 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1098 symval->name = ef->ddbstrtab + es->st_name;
1099 symval->value = (caddr_t) ef->address + es->st_value;
1100 symval->size = es->st_size;
1101 return 0;
1102 }
1103 return ENOENT;
1104 }
1105
1106 static int
1107 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1108 c_linker_sym_t* sym, long* diffp)
1109 {
1110 elf_file_t ef = (elf_file_t) lf;
1111 u_long off = (uintptr_t) (void *) value;
1112 u_long diff = off;
1113 u_long st_value;
1114 const Elf_Sym* es;
1115 const Elf_Sym* best = 0;
1116 int i;
1117
1118 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1119 if (es->st_name == 0)
1120 continue;
1121 st_value = es->st_value + (uintptr_t) (void *) ef->address;
1122 if (off >= st_value) {
1123 if (off - st_value < diff) {
1124 diff = off - st_value;
1125 best = es;
1126 if (diff == 0)
1127 break;
1128 } else if (off - st_value == diff) {
1129 best = es;
1130 }
1131 }
1132 }
1133 if (best == 0)
1134 *diffp = off;
1135 else
1136 *diffp = diff;
1137 *sym = (c_linker_sym_t) best;
1138
1139 return 0;
1140 }
1141
1142 /*
1143 * Look up a linker set on an ELF system.
1144 */
1145 static int
1146 link_elf_lookup_set(linker_file_t lf, const char *name,
1147 void ***startp, void ***stopp, int *countp)
1148 {
1149 c_linker_sym_t sym;
1150 linker_symval_t symval;
1151 char *setsym;
1152 void **start, **stop;
1153 int len, error = 0, count;
1154
1155 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1156 setsym = malloc(len, M_LINKER, M_WAITOK);
1157 if (setsym == NULL)
1158 return ENOMEM;
1159
1160 /* get address of first entry */
1161 snprintf(setsym, len, "%s%s", "__start_set_", name);
1162 error = link_elf_lookup_symbol(lf, setsym, &sym);
1163 if (error)
1164 goto out;
1165 link_elf_symbol_values(lf, sym, &symval);
1166 if (symval.value == 0) {
1167 error = ESRCH;
1168 goto out;
1169 }
1170 start = (void **)symval.value;
1171
1172 /* get address of last entry */
1173 snprintf(setsym, len, "%s%s", "__stop_set_", name);
1174 error = link_elf_lookup_symbol(lf, setsym, &sym);
1175 if (error)
1176 goto out;
1177 link_elf_symbol_values(lf, sym, &symval);
1178 if (symval.value == 0) {
1179 error = ESRCH;
1180 goto out;
1181 }
1182 stop = (void **)symval.value;
1183
1184 /* and the number of entries */
1185 count = stop - start;
1186
1187 /* and copy out */
1188 if (startp)
1189 *startp = start;
1190 if (stopp)
1191 *stopp = stop;
1192 if (countp)
1193 *countp = count;
1194
1195 out:
1196 free(setsym, M_LINKER);
1197 return error;
1198 }
1199
1200 static int
1201 link_elf_each_function_name(linker_file_t file,
1202 int (*callback)(const char *, void *), void *opaque) {
1203 elf_file_t ef = (elf_file_t)file;
1204 const Elf_Sym* symp;
1205 int i, error;
1206
1207 /* Exhaustive search */
1208 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1209 if (symp->st_value != 0 &&
1210 ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1211 error = callback(ef->ddbstrtab + symp->st_name, opaque);
1212 if (error)
1213 return (error);
1214 }
1215 }
1216 return (0);
1217 }
1218
1219 #ifdef __ia64__
1220 /*
1221 * Each KLD has its own GP. The GP value for each load module is given by
1222 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
1223 * don't have direct access to the ELF file structure. The link_elf_get_gp()
1224 * function returns the GP given a pointer to a generic linker file struct.
1225 */
1226 Elf_Addr
1227 link_elf_get_gp(linker_file_t lf)
1228 {
1229 elf_file_t ef = (elf_file_t)lf;
1230 return (Elf_Addr)ef->got;
1231 }
1232 #endif
1233
1234 const Elf_Sym *
1235 elf_get_sym(linker_file_t lf, Elf_Size symidx)
1236 {
1237 elf_file_t ef = (elf_file_t)lf;
1238
1239 if (symidx >= ef->nchains)
1240 return (NULL);
1241 return (ef->symtab + symidx);
1242 }
1243
1244 const char *
1245 elf_get_symname(linker_file_t lf, Elf_Size symidx)
1246 {
1247 elf_file_t ef = (elf_file_t)lf;
1248 const Elf_Sym *sym;
1249
1250 if (symidx >= ef->nchains)
1251 return (NULL);
1252 sym = ef->symtab + symidx;
1253 return (ef->strtab + sym->st_name);
1254 }
1255
1256 /*
1257 * Symbol lookup function that can be used when the symbol index is known (ie
1258 * in relocations). It uses the symbol index instead of doing a fully fledged
1259 * hash table based lookup when such is valid. For example for local symbols.
1260 * This is not only more efficient, it's also more correct. It's not always
1261 * the case that the symbol can be found through the hash table.
1262 */
1263 static Elf_Addr
1264 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
1265 {
1266 elf_file_t ef = (elf_file_t)lf;
1267 const Elf_Sym *sym;
1268 const char *symbol;
1269
1270 /* Don't even try to lookup the symbol if the index is bogus. */
1271 if (symidx >= ef->nchains)
1272 return (0);
1273
1274 sym = ef->symtab + symidx;
1275
1276 /*
1277 * Don't do a full lookup when the symbol is local. It may even
1278 * fail because it may not be found through the hash table.
1279 */
1280 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1281 /* Force lookup failure when we have an insanity. */
1282 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1283 return (0);
1284 return ((Elf_Addr)ef->address + sym->st_value);
1285 }
1286
1287 /*
1288 * XXX we can avoid doing a hash table based lookup for global
1289 * symbols as well. This however is not always valid, so we'll
1290 * just do it the hard way for now. Performance tweaks can
1291 * always be added.
1292 */
1293
1294 symbol = ef->strtab + sym->st_name;
1295
1296 /* Force a lookup failure if the symbol name is bogus. */
1297 if (*symbol == 0)
1298 return (0);
1299
1300 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1301 }
1302
1303 static void
1304 link_elf_reloc_local(linker_file_t lf)
1305 {
1306 const Elf_Rel *rellim;
1307 const Elf_Rel *rel;
1308 const Elf_Rela *relalim;
1309 const Elf_Rela *rela;
1310 elf_file_t ef = (elf_file_t)lf;
1311
1312 /* Perform relocations without addend if there are any: */
1313 if ((rel = ef->rel) != NULL) {
1314 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1315 while (rel < rellim) {
1316 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
1317 elf_lookup);
1318 rel++;
1319 }
1320 }
1321
1322 /* Perform relocations with addend if there are any: */
1323 if ((rela = ef->rela) != NULL) {
1324 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
1325 while (rela < relalim) {
1326 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
1327 elf_lookup);
1328 rela++;
1329 }
1330 }
1331 }
Cache object: 67b64ba8582997927000763ed7750b93
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