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("$FreeBSD$");
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/malloc.h>
41 #include <sys/mutex.h>
42 #include <sys/mount.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 <security/mac/mac_framework.h>
52
53 #include <vm/vm.h>
54 #include <vm/vm_param.h>
55 #ifdef SPARSE_MAPPING
56 #include <vm/vm_object.h>
57 #include <vm/vm_kern.h>
58 #include <vm/vm_extern.h>
59 #endif
60 #include <vm/pmap.h>
61 #include <vm/vm_map.h>
62
63 #include <sys/link_elf.h>
64
65 #include "linker_if.h"
66
67 #define MAXSEGS 4
68
69 typedef struct elf_file {
70 struct linker_file lf; /* Common fields */
71 int preloaded; /* Was file pre-loaded */
72 caddr_t address; /* Relocation address */
73 #ifdef SPARSE_MAPPING
74 vm_object_t object; /* VM object to hold file pages */
75 #endif
76 Elf_Dyn* dynamic; /* Symbol table etc. */
77 Elf_Hashelt nbuckets; /* DT_HASH info */
78 Elf_Hashelt nchains;
79 const Elf_Hashelt* buckets;
80 const Elf_Hashelt* chains;
81 caddr_t hash;
82 caddr_t strtab; /* DT_STRTAB */
83 int strsz; /* DT_STRSZ */
84 const Elf_Sym* symtab; /* DT_SYMTAB */
85 Elf_Addr* got; /* DT_PLTGOT */
86 const Elf_Rel* pltrel; /* DT_JMPREL */
87 int pltrelsize; /* DT_PLTRELSZ */
88 const Elf_Rela* pltrela; /* DT_JMPREL */
89 int pltrelasize; /* DT_PLTRELSZ */
90 const Elf_Rel* rel; /* DT_REL */
91 int relsize; /* DT_RELSZ */
92 const Elf_Rela* rela; /* DT_RELA */
93 int relasize; /* DT_RELASZ */
94 caddr_t modptr;
95 const Elf_Sym* ddbsymtab; /* The symbol table we are using */
96 long ddbsymcnt; /* Number of symbols */
97 caddr_t ddbstrtab; /* String table */
98 long ddbstrcnt; /* number of bytes in string table */
99 caddr_t symbase; /* malloc'ed symbold base */
100 caddr_t strbase; /* malloc'ed string base */
101 #ifdef GDB
102 struct link_map gdb; /* hooks for gdb */
103 #endif
104 } *elf_file_t;
105
106 static int link_elf_link_common_finish(linker_file_t);
107 static int link_elf_link_preload(linker_class_t cls,
108 const char*, linker_file_t*);
109 static int link_elf_link_preload_finish(linker_file_t);
110 static int link_elf_load_file(linker_class_t, const char*, linker_file_t*);
111 static int link_elf_lookup_symbol(linker_file_t, const char*,
112 c_linker_sym_t*);
113 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
114 static int link_elf_search_symbol(linker_file_t, caddr_t value,
115 c_linker_sym_t* sym, long* diffp);
116
117 static void link_elf_unload_file(linker_file_t);
118 static void link_elf_unload_preload(linker_file_t);
119 static int link_elf_lookup_set(linker_file_t, const char *,
120 void ***, void ***, int *);
121 static int link_elf_each_function_name(linker_file_t,
122 int (*)(const char *, void *),
123 void *);
124 static void link_elf_reloc_local(linker_file_t);
125 static Elf_Addr elf_lookup(linker_file_t lf, Elf_Size symidx, int deps);
126
127 static kobj_method_t link_elf_methods[] = {
128 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
129 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
130 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
131 KOBJMETHOD(linker_unload, link_elf_unload_file),
132 KOBJMETHOD(linker_load_file, link_elf_load_file),
133 KOBJMETHOD(linker_link_preload, link_elf_link_preload),
134 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
135 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set),
136 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
137 { 0, 0 }
138 };
139
140 static struct linker_class link_elf_class = {
141 #if ELF_TARG_CLASS == ELFCLASS32
142 "elf32",
143 #else
144 "elf64",
145 #endif
146 link_elf_methods, sizeof(struct elf_file)
147 };
148
149 static int parse_dynamic(elf_file_t ef);
150 static int relocate_file(elf_file_t ef);
151 static int link_elf_preload_parse_symbols(elf_file_t ef);
152
153 #ifdef GDB
154 static void r_debug_state(struct r_debug *dummy_one,
155 struct link_map *dummy_two);
156
157 /*
158 * A list of loaded modules for GDB to use for loading symbols.
159 */
160 struct r_debug r_debug;
161
162 #define GDB_STATE(s) r_debug.r_state = s; r_debug_state(NULL, NULL);
163
164 /*
165 * Function for the debugger to set a breakpoint on to gain control.
166 */
167 static void
168 r_debug_state(struct r_debug *dummy_one __unused,
169 struct link_map *dummy_two __unused)
170 {
171 }
172
173 static void
174 link_elf_add_gdb(struct link_map *l)
175 {
176 struct link_map *prev;
177
178 l->l_next = NULL;
179
180 if (r_debug.r_map == NULL) {
181 /* Add first. */
182 l->l_prev = NULL;
183 r_debug.r_map = l;
184 } else {
185 /* Append to list. */
186 for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
187 ;
188 l->l_prev = prev;
189 prev->l_next = l;
190 }
191 }
192
193 static void
194 link_elf_delete_gdb(struct link_map *l)
195 {
196 if (l->l_prev == NULL) {
197 /* Remove first. */
198 if ((r_debug.r_map = l->l_next) != NULL)
199 l->l_next->l_prev = NULL;
200 } else {
201 /* Remove any but first. */
202 if ((l->l_prev->l_next = l->l_next) != NULL)
203 l->l_next->l_prev = l->l_prev;
204 }
205 }
206 #endif /* GDB */
207
208 #ifdef __ia64__
209 Elf_Addr link_elf_get_gp(linker_file_t);
210 #endif
211
212 /*
213 * The kernel symbol table starts here.
214 */
215 extern struct _dynamic _DYNAMIC;
216
217 static void
218 link_elf_error(const char *s)
219 {
220 printf("kldload: %s\n", s);
221 }
222
223 /*
224 * Actions performed after linking/loading both the preloaded kernel and any
225 * modules; whether preloaded or dynamicly loaded.
226 */
227 static int
228 link_elf_link_common_finish(linker_file_t lf)
229 {
230 #ifdef GDB
231 elf_file_t ef = (elf_file_t)lf;
232 char *newfilename;
233 #endif
234 int error;
235
236 /* Notify MD code that a module is being loaded. */
237 error = elf_cpu_load_file(lf);
238 if (error)
239 return (error);
240
241 #ifdef GDB
242 GDB_STATE(RT_ADD);
243 ef->gdb.l_addr = lf->address;
244 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
245 strcpy(newfilename, lf->filename);
246 ef->gdb.l_name = newfilename;
247 ef->gdb.l_ld = ef->dynamic;
248 link_elf_add_gdb(&ef->gdb);
249 GDB_STATE(RT_CONSISTENT);
250 #endif
251
252 return (0);
253 }
254
255 static void
256 link_elf_init(void* arg)
257 {
258 Elf_Dyn *dp;
259 caddr_t modptr, baseptr, sizeptr;
260 elf_file_t ef;
261 char *modname;
262
263 linker_add_class(&link_elf_class);
264
265 dp = (Elf_Dyn*) &_DYNAMIC;
266 modname = NULL;
267 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
268 if (modptr == NULL)
269 modptr = preload_search_by_type("elf kernel");
270 if (modptr)
271 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
272 if (modname == NULL)
273 modname = "kernel";
274 linker_kernel_file = linker_make_file(modname, &link_elf_class);
275 if (linker_kernel_file == NULL)
276 panic("link_elf_init: Can't create linker structures for kernel");
277
278 ef = (elf_file_t) linker_kernel_file;
279 ef->preloaded = 1;
280 ef->address = 0;
281 #ifdef SPARSE_MAPPING
282 ef->object = 0;
283 #endif
284 ef->dynamic = dp;
285
286 if (dp)
287 parse_dynamic(ef);
288 linker_kernel_file->address = (caddr_t) KERNBASE;
289 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
290
291 if (modptr) {
292 ef->modptr = modptr;
293 baseptr = preload_search_info(modptr, MODINFO_ADDR);
294 if (baseptr)
295 linker_kernel_file->address = *(caddr_t *)baseptr;
296 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
297 if (sizeptr)
298 linker_kernel_file->size = *(size_t *)sizeptr;
299 }
300 (void)link_elf_preload_parse_symbols(ef);
301
302 #ifdef GDB
303 r_debug.r_map = NULL;
304 r_debug.r_brk = r_debug_state;
305 r_debug.r_state = RT_CONSISTENT;
306 #endif
307
308 (void)link_elf_link_common_finish(linker_kernel_file);
309 linker_kernel_file->flags |= LINKER_FILE_LINKED;
310 }
311
312 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, 0);
313
314 static int
315 link_elf_preload_parse_symbols(elf_file_t ef)
316 {
317 caddr_t pointer;
318 caddr_t ssym, esym, base;
319 caddr_t strtab;
320 int strcnt;
321 Elf_Sym* symtab;
322 int symcnt;
323
324 if (ef->modptr == NULL)
325 return 0;
326 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
327 if (pointer == NULL)
328 return 0;
329 ssym = *(caddr_t *)pointer;
330 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
331 if (pointer == NULL)
332 return 0;
333 esym = *(caddr_t *)pointer;
334
335 base = ssym;
336
337 symcnt = *(long *)base;
338 base += sizeof(long);
339 symtab = (Elf_Sym *)base;
340 base += roundup(symcnt, sizeof(long));
341
342 if (base > esym || base < ssym) {
343 printf("Symbols are corrupt!\n");
344 return EINVAL;
345 }
346
347 strcnt = *(long *)base;
348 base += sizeof(long);
349 strtab = base;
350 base += roundup(strcnt, sizeof(long));
351
352 if (base > esym || base < ssym) {
353 printf("Symbols are corrupt!\n");
354 return EINVAL;
355 }
356
357 ef->ddbsymtab = symtab;
358 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
359 ef->ddbstrtab = strtab;
360 ef->ddbstrcnt = strcnt;
361
362 return 0;
363 }
364
365 static int
366 parse_dynamic(elf_file_t ef)
367 {
368 Elf_Dyn *dp;
369 int plttype = DT_REL;
370
371 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
372 switch (dp->d_tag) {
373 case DT_HASH:
374 {
375 /* From src/libexec/rtld-elf/rtld.c */
376 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
377 (ef->address + dp->d_un.d_ptr);
378 ef->nbuckets = hashtab[0];
379 ef->nchains = hashtab[1];
380 ef->buckets = hashtab + 2;
381 ef->chains = ef->buckets + ef->nbuckets;
382 break;
383 }
384 case DT_STRTAB:
385 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
386 break;
387 case DT_STRSZ:
388 ef->strsz = dp->d_un.d_val;
389 break;
390 case DT_SYMTAB:
391 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
392 break;
393 case DT_SYMENT:
394 if (dp->d_un.d_val != sizeof(Elf_Sym))
395 return ENOEXEC;
396 break;
397 case DT_PLTGOT:
398 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
399 break;
400 case DT_REL:
401 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
402 break;
403 case DT_RELSZ:
404 ef->relsize = dp->d_un.d_val;
405 break;
406 case DT_RELENT:
407 if (dp->d_un.d_val != sizeof(Elf_Rel))
408 return ENOEXEC;
409 break;
410 case DT_JMPREL:
411 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
412 break;
413 case DT_PLTRELSZ:
414 ef->pltrelsize = dp->d_un.d_val;
415 break;
416 case DT_RELA:
417 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
418 break;
419 case DT_RELASZ:
420 ef->relasize = dp->d_un.d_val;
421 break;
422 case DT_RELAENT:
423 if (dp->d_un.d_val != sizeof(Elf_Rela))
424 return ENOEXEC;
425 break;
426 case DT_PLTREL:
427 plttype = dp->d_un.d_val;
428 if (plttype != DT_REL && plttype != DT_RELA)
429 return ENOEXEC;
430 break;
431 #ifdef GDB
432 case DT_DEBUG:
433 dp->d_un.d_ptr = (Elf_Addr) &r_debug;
434 break;
435 #endif
436 }
437 }
438
439 if (plttype == DT_RELA) {
440 ef->pltrela = (const Elf_Rela *) ef->pltrel;
441 ef->pltrel = NULL;
442 ef->pltrelasize = ef->pltrelsize;
443 ef->pltrelsize = 0;
444 }
445
446 ef->ddbsymtab = ef->symtab;
447 ef->ddbsymcnt = ef->nchains;
448 ef->ddbstrtab = ef->strtab;
449 ef->ddbstrcnt = ef->strsz;
450
451 return 0;
452 }
453
454 static int
455 link_elf_link_preload(linker_class_t cls,
456 const char* filename, linker_file_t *result)
457 {
458 caddr_t modptr, baseptr, sizeptr, dynptr;
459 char *type;
460 elf_file_t ef;
461 linker_file_t lf;
462 int error;
463 vm_offset_t dp;
464
465 /* Look to see if we have the file preloaded */
466 modptr = preload_search_by_name(filename);
467 if (modptr == NULL)
468 return ENOENT;
469
470 type = (char *)preload_search_info(modptr, MODINFO_TYPE);
471 baseptr = preload_search_info(modptr, MODINFO_ADDR);
472 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
473 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
474 if (type == NULL ||
475 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
476 strcmp(type, "elf module") != 0))
477 return (EFTYPE);
478 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
479 return (EINVAL);
480
481 lf = linker_make_file(filename, &link_elf_class);
482 if (lf == NULL) {
483 return ENOMEM;
484 }
485
486 ef = (elf_file_t) lf;
487 ef->preloaded = 1;
488 ef->modptr = modptr;
489 ef->address = *(caddr_t *)baseptr;
490 #ifdef SPARSE_MAPPING
491 ef->object = 0;
492 #endif
493 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
494 ef->dynamic = (Elf_Dyn *)dp;
495 lf->address = ef->address;
496 lf->size = *(size_t *)sizeptr;
497
498 error = parse_dynamic(ef);
499 if (error) {
500 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
501 return error;
502 }
503 link_elf_reloc_local(lf);
504 *result = lf;
505 return (0);
506 }
507
508 static int
509 link_elf_link_preload_finish(linker_file_t lf)
510 {
511 elf_file_t ef;
512 int error;
513
514 ef = (elf_file_t) lf;
515 #if 0 /* this will be more trouble than it's worth for now */
516 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
517 if (dp->d_tag != DT_NEEDED)
518 continue;
519 modname = ef->strtab + dp->d_un.d_val;
520 error = linker_load_module(modname, lf);
521 if (error)
522 goto out;
523 }
524 #endif
525 error = relocate_file(ef);
526 if (error)
527 return error;
528 (void)link_elf_preload_parse_symbols(ef);
529
530 return (link_elf_link_common_finish(lf));
531 }
532
533 static int
534 link_elf_load_file(linker_class_t cls, const char* filename,
535 linker_file_t* result)
536 {
537 struct nameidata nd;
538 struct thread* td = curthread; /* XXX */
539 Elf_Ehdr *hdr;
540 caddr_t firstpage;
541 int nbytes, i;
542 Elf_Phdr *phdr;
543 Elf_Phdr *phlimit;
544 Elf_Phdr *segs[MAXSEGS];
545 int nsegs;
546 Elf_Phdr *phdyn;
547 Elf_Phdr *phphdr;
548 caddr_t mapbase;
549 size_t mapsize;
550 Elf_Off base_offset;
551 Elf_Addr base_vaddr;
552 Elf_Addr base_vlimit;
553 int error = 0;
554 int resid, flags;
555 elf_file_t ef;
556 linker_file_t lf;
557 Elf_Shdr *shdr;
558 int symtabindex;
559 int symstrindex;
560 int symcnt;
561 int strcnt;
562 int vfslocked;
563
564 shdr = NULL;
565 lf = NULL;
566
567 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, filename, td);
568 flags = FREAD;
569 error = vn_open(&nd, &flags, 0, NULL);
570 if (error)
571 return error;
572 vfslocked = NDHASGIANT(&nd);
573 NDFREE(&nd, NDF_ONLY_PNBUF);
574 #ifdef MAC
575 error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp);
576 if (error) {
577 firstpage = NULL;
578 goto out;
579 }
580 #endif
581
582 /*
583 * Read the elf header from the file.
584 */
585 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
586 if (firstpage == NULL) {
587 error = ENOMEM;
588 goto out;
589 }
590 hdr = (Elf_Ehdr *)firstpage;
591 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
592 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
593 &resid, td);
594 nbytes = PAGE_SIZE - resid;
595 if (error)
596 goto out;
597
598 if (!IS_ELF(*hdr)) {
599 error = ENOEXEC;
600 goto out;
601 }
602
603 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
604 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
605 link_elf_error("Unsupported file layout");
606 error = ENOEXEC;
607 goto out;
608 }
609 if (hdr->e_ident[EI_VERSION] != EV_CURRENT
610 || hdr->e_version != EV_CURRENT) {
611 link_elf_error("Unsupported file version");
612 error = ENOEXEC;
613 goto out;
614 }
615 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
616 link_elf_error("Unsupported file type");
617 error = ENOEXEC;
618 goto out;
619 }
620 if (hdr->e_machine != ELF_TARG_MACH) {
621 link_elf_error("Unsupported machine");
622 error = ENOEXEC;
623 goto out;
624 }
625
626 /*
627 * We rely on the program header being in the first page. This is
628 * not strictly required by the ABI specification, but it seems to
629 * always true in practice. And, it simplifies things considerably.
630 */
631 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
632 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
633 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
634 link_elf_error("Unreadable program headers");
635
636 /*
637 * Scan the program header entries, and save key information.
638 *
639 * We rely on there being exactly two load segments, text and data,
640 * in that order.
641 */
642 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
643 phlimit = phdr + hdr->e_phnum;
644 nsegs = 0;
645 phdyn = NULL;
646 phphdr = NULL;
647 while (phdr < phlimit) {
648 switch (phdr->p_type) {
649
650 case PT_LOAD:
651 if (nsegs == MAXSEGS) {
652 link_elf_error("Too many sections");
653 error = ENOEXEC;
654 goto out;
655 }
656 /*
657 * XXX: We just trust they come in right order ??
658 */
659 segs[nsegs] = phdr;
660 ++nsegs;
661 break;
662
663 case PT_PHDR:
664 phphdr = phdr;
665 break;
666
667 case PT_DYNAMIC:
668 phdyn = phdr;
669 break;
670
671 case PT_INTERP:
672 link_elf_error("Unsupported file type");
673 error = ENOEXEC;
674 goto out;
675 }
676
677 ++phdr;
678 }
679 if (phdyn == NULL) {
680 link_elf_error("Object is not dynamically-linked");
681 error = ENOEXEC;
682 goto out;
683 }
684 if (nsegs == 0) {
685 link_elf_error("No sections");
686 error = ENOEXEC;
687 goto out;
688 }
689
690 /*
691 * Allocate the entire address space of the object, to stake out our
692 * contiguous region, and to establish the base address for relocation.
693 */
694 base_offset = trunc_page(segs[0]->p_offset);
695 base_vaddr = trunc_page(segs[0]->p_vaddr);
696 base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
697 segs[nsegs - 1]->p_memsz);
698 mapsize = base_vlimit - base_vaddr;
699
700 lf = linker_make_file(filename, &link_elf_class);
701 if (!lf) {
702 error = ENOMEM;
703 goto out;
704 }
705
706 ef = (elf_file_t) lf;
707 #ifdef SPARSE_MAPPING
708 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
709 if (ef->object == NULL) {
710 error = ENOMEM;
711 goto out;
712 }
713 ef->address = (caddr_t) vm_map_min(kernel_map);
714 error = vm_map_find(kernel_map, ef->object, 0,
715 (vm_offset_t *) &ef->address,
716 mapsize, 1,
717 VM_PROT_ALL, VM_PROT_ALL, 0);
718 if (error) {
719 vm_object_deallocate(ef->object);
720 ef->object = 0;
721 goto out;
722 }
723 #else
724 ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
725 if (!ef->address) {
726 error = ENOMEM;
727 goto out;
728 }
729 #endif
730 mapbase = ef->address;
731
732 /*
733 * Read the text and data sections and zero the bss.
734 */
735 for (i = 0; i < nsegs; i++) {
736 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
737 error = vn_rdwr(UIO_READ, nd.ni_vp,
738 segbase, segs[i]->p_filesz, segs[i]->p_offset,
739 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
740 &resid, td);
741 if (error) {
742 goto out;
743 }
744 bzero(segbase + segs[i]->p_filesz,
745 segs[i]->p_memsz - segs[i]->p_filesz);
746
747 #ifdef SPARSE_MAPPING
748 /*
749 * Wire down the pages
750 */
751 error = vm_map_wire(kernel_map,
752 (vm_offset_t) segbase,
753 (vm_offset_t) segbase + segs[i]->p_memsz,
754 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
755 if (error != KERN_SUCCESS) {
756 error = ENOMEM;
757 goto out;
758 }
759 #endif
760 }
761
762 #ifdef GPROF
763 /* Update profiling information with the new text segment. */
764 mtx_lock(&Giant);
765 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
766 segs[0]->p_memsz));
767 mtx_unlock(&Giant);
768 #endif
769
770 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
771
772 lf->address = ef->address;
773 lf->size = mapsize;
774
775 error = parse_dynamic(ef);
776 if (error)
777 goto out;
778 link_elf_reloc_local(lf);
779
780 error = linker_load_dependencies(lf);
781 if (error)
782 goto out;
783 #if 0 /* this will be more trouble than it's worth for now */
784 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
785 if (dp->d_tag != DT_NEEDED)
786 continue;
787 modname = ef->strtab + dp->d_un.d_val;
788 error = linker_load_module(modname, lf);
789 if (error)
790 goto out;
791 }
792 #endif
793 error = relocate_file(ef);
794 if (error)
795 goto out;
796
797 /* Try and load the symbol table if it's present. (you can strip it!) */
798 nbytes = hdr->e_shnum * hdr->e_shentsize;
799 if (nbytes == 0 || hdr->e_shoff == 0)
800 goto nosyms;
801 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
802 if (shdr == NULL) {
803 error = ENOMEM;
804 goto out;
805 }
806 error = vn_rdwr(UIO_READ, nd.ni_vp,
807 (caddr_t)shdr, nbytes, hdr->e_shoff,
808 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
809 &resid, td);
810 if (error)
811 goto out;
812 symtabindex = -1;
813 symstrindex = -1;
814 for (i = 0; i < hdr->e_shnum; i++) {
815 if (shdr[i].sh_type == SHT_SYMTAB) {
816 symtabindex = i;
817 symstrindex = shdr[i].sh_link;
818 }
819 }
820 if (symtabindex < 0 || symstrindex < 0)
821 goto nosyms;
822
823 symcnt = shdr[symtabindex].sh_size;
824 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
825 strcnt = shdr[symstrindex].sh_size;
826 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
827
828 if (ef->symbase == NULL || ef->strbase == NULL) {
829 error = ENOMEM;
830 goto out;
831 }
832 error = vn_rdwr(UIO_READ, nd.ni_vp,
833 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
834 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
835 &resid, td);
836 if (error)
837 goto out;
838 error = vn_rdwr(UIO_READ, nd.ni_vp,
839 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
840 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
841 &resid, td);
842 if (error)
843 goto out;
844
845 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
846 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
847 ef->ddbstrcnt = strcnt;
848 ef->ddbstrtab = ef->strbase;
849
850 error = link_elf_link_common_finish(lf);
851 if (error)
852 goto out;
853
854 nosyms:
855
856 *result = lf;
857
858 out:
859 if (error && lf)
860 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
861 if (shdr)
862 free(shdr, M_LINKER);
863 if (firstpage)
864 free(firstpage, M_LINKER);
865 VOP_UNLOCK(nd.ni_vp, 0, td);
866 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
867 VFS_UNLOCK_GIANT(vfslocked);
868
869 return error;
870 }
871
872 static void
873 link_elf_unload_file(linker_file_t file)
874 {
875 elf_file_t ef = (elf_file_t) file;
876
877 #ifdef GDB
878 if (ef->gdb.l_ld) {
879 GDB_STATE(RT_DELETE);
880 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
881 link_elf_delete_gdb(&ef->gdb);
882 GDB_STATE(RT_CONSISTENT);
883 }
884 #endif
885
886 /* Notify MD code that a module is being unloaded. */
887 elf_cpu_unload_file(file);
888
889 if (ef->preloaded) {
890 link_elf_unload_preload(file);
891 return;
892 }
893
894 #ifdef SPARSE_MAPPING
895 if (ef->object) {
896 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
897 (vm_offset_t) ef->address
898 + (ef->object->size << PAGE_SHIFT));
899 }
900 #else
901 if (ef->address)
902 free(ef->address, M_LINKER);
903 #endif
904 if (ef->symbase)
905 free(ef->symbase, M_LINKER);
906 if (ef->strbase)
907 free(ef->strbase, M_LINKER);
908 }
909
910 static void
911 link_elf_unload_preload(linker_file_t file)
912 {
913 if (file->filename)
914 preload_delete_name(file->filename);
915 }
916
917 static const char *
918 symbol_name(elf_file_t ef, Elf_Size r_info)
919 {
920 const Elf_Sym *ref;
921
922 if (ELF_R_SYM(r_info)) {
923 ref = ef->symtab + ELF_R_SYM(r_info);
924 return ef->strtab + ref->st_name;
925 } else
926 return NULL;
927 }
928
929 static int
930 relocate_file(elf_file_t ef)
931 {
932 const Elf_Rel *rellim;
933 const Elf_Rel *rel;
934 const Elf_Rela *relalim;
935 const Elf_Rela *rela;
936 const char *symname;
937
938 /* Perform relocations without addend if there are any: */
939 rel = ef->rel;
940 if (rel) {
941 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
942 while (rel < rellim) {
943 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
944 elf_lookup)) {
945 symname = symbol_name(ef, rel->r_info);
946 printf("link_elf: symbol %s undefined\n", symname);
947 return ENOENT;
948 }
949 rel++;
950 }
951 }
952
953 /* Perform relocations with addend if there are any: */
954 rela = ef->rela;
955 if (rela) {
956 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
957 while (rela < relalim) {
958 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
959 elf_lookup)) {
960 symname = symbol_name(ef, rela->r_info);
961 printf("link_elf: symbol %s undefined\n", symname);
962 return ENOENT;
963 }
964 rela++;
965 }
966 }
967
968 /* Perform PLT relocations without addend if there are any: */
969 rel = ef->pltrel;
970 if (rel) {
971 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
972 while (rel < rellim) {
973 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
974 elf_lookup)) {
975 symname = symbol_name(ef, rel->r_info);
976 printf("link_elf: symbol %s undefined\n", symname);
977 return ENOENT;
978 }
979 rel++;
980 }
981 }
982
983 /* Perform relocations with addend if there are any: */
984 rela = ef->pltrela;
985 if (rela) {
986 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
987 while (rela < relalim) {
988 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
989 elf_lookup)) {
990 symname = symbol_name(ef, rela->r_info);
991 printf("link_elf: symbol %s undefined\n", symname);
992 return ENOENT;
993 }
994 rela++;
995 }
996 }
997
998 return 0;
999 }
1000
1001 /*
1002 * Hash function for symbol table lookup. Don't even think about changing
1003 * this. It is specified by the System V ABI.
1004 */
1005 static unsigned long
1006 elf_hash(const char *name)
1007 {
1008 const unsigned char *p = (const unsigned char *) name;
1009 unsigned long h = 0;
1010 unsigned long g;
1011
1012 while (*p != '\0') {
1013 h = (h << 4) + *p++;
1014 if ((g = h & 0xf0000000) != 0)
1015 h ^= g >> 24;
1016 h &= ~g;
1017 }
1018 return h;
1019 }
1020
1021 static int
1022 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
1023 {
1024 elf_file_t ef = (elf_file_t) lf;
1025 unsigned long symnum;
1026 const Elf_Sym* symp;
1027 const char *strp;
1028 unsigned long hash;
1029 int i;
1030
1031 /* If we don't have a hash, bail. */
1032 if (ef->buckets == NULL || ef->nbuckets == 0) {
1033 printf("link_elf_lookup_symbol: missing symbol hash table\n");
1034 return ENOENT;
1035 }
1036
1037 /* First, search hashed global symbols */
1038 hash = elf_hash(name);
1039 symnum = ef->buckets[hash % ef->nbuckets];
1040
1041 while (symnum != STN_UNDEF) {
1042 if (symnum >= ef->nchains) {
1043 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1044 return ENOENT;
1045 }
1046
1047 symp = ef->symtab + symnum;
1048 if (symp->st_name == 0) {
1049 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1050 return ENOENT;
1051 }
1052
1053 strp = ef->strtab + symp->st_name;
1054
1055 if (strcmp(name, strp) == 0) {
1056 if (symp->st_shndx != SHN_UNDEF ||
1057 (symp->st_value != 0 &&
1058 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1059 *sym = (c_linker_sym_t) symp;
1060 return 0;
1061 } else
1062 return ENOENT;
1063 }
1064
1065 symnum = ef->chains[symnum];
1066 }
1067
1068 /* If we have not found it, look at the full table (if loaded) */
1069 if (ef->symtab == ef->ddbsymtab)
1070 return ENOENT;
1071
1072 /* Exhaustive search */
1073 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1074 strp = ef->ddbstrtab + symp->st_name;
1075 if (strcmp(name, strp) == 0) {
1076 if (symp->st_shndx != SHN_UNDEF ||
1077 (symp->st_value != 0 &&
1078 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1079 *sym = (c_linker_sym_t) symp;
1080 return 0;
1081 } else
1082 return ENOENT;
1083 }
1084 }
1085
1086 return ENOENT;
1087 }
1088
1089 static int
1090 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1091 {
1092 elf_file_t ef = (elf_file_t) lf;
1093 const Elf_Sym* es = (const Elf_Sym*) sym;
1094
1095 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1096 symval->name = ef->strtab + es->st_name;
1097 symval->value = (caddr_t) ef->address + es->st_value;
1098 symval->size = es->st_size;
1099 return 0;
1100 }
1101 if (ef->symtab == ef->ddbsymtab)
1102 return ENOENT;
1103 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1104 symval->name = ef->ddbstrtab + es->st_name;
1105 symval->value = (caddr_t) ef->address + es->st_value;
1106 symval->size = es->st_size;
1107 return 0;
1108 }
1109 return ENOENT;
1110 }
1111
1112 static int
1113 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1114 c_linker_sym_t* sym, long* diffp)
1115 {
1116 elf_file_t ef = (elf_file_t) lf;
1117 u_long off = (uintptr_t) (void *) value;
1118 u_long diff = off;
1119 u_long st_value;
1120 const Elf_Sym* es;
1121 const Elf_Sym* best = 0;
1122 int i;
1123
1124 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1125 if (es->st_name == 0)
1126 continue;
1127 st_value = es->st_value + (uintptr_t) (void *) ef->address;
1128 if (off >= st_value) {
1129 if (off - st_value < diff) {
1130 diff = off - st_value;
1131 best = es;
1132 if (diff == 0)
1133 break;
1134 } else if (off - st_value == diff) {
1135 best = es;
1136 }
1137 }
1138 }
1139 if (best == 0)
1140 *diffp = off;
1141 else
1142 *diffp = diff;
1143 *sym = (c_linker_sym_t) best;
1144
1145 return 0;
1146 }
1147
1148 /*
1149 * Look up a linker set on an ELF system.
1150 */
1151 static int
1152 link_elf_lookup_set(linker_file_t lf, const char *name,
1153 void ***startp, void ***stopp, int *countp)
1154 {
1155 c_linker_sym_t sym;
1156 linker_symval_t symval;
1157 char *setsym;
1158 void **start, **stop;
1159 int len, error = 0, count;
1160
1161 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1162 setsym = malloc(len, M_LINKER, M_WAITOK);
1163 if (setsym == NULL)
1164 return ENOMEM;
1165
1166 /* get address of first entry */
1167 snprintf(setsym, len, "%s%s", "__start_set_", name);
1168 error = link_elf_lookup_symbol(lf, setsym, &sym);
1169 if (error)
1170 goto out;
1171 link_elf_symbol_values(lf, sym, &symval);
1172 if (symval.value == 0) {
1173 error = ESRCH;
1174 goto out;
1175 }
1176 start = (void **)symval.value;
1177
1178 /* get address of last entry */
1179 snprintf(setsym, len, "%s%s", "__stop_set_", name);
1180 error = link_elf_lookup_symbol(lf, setsym, &sym);
1181 if (error)
1182 goto out;
1183 link_elf_symbol_values(lf, sym, &symval);
1184 if (symval.value == 0) {
1185 error = ESRCH;
1186 goto out;
1187 }
1188 stop = (void **)symval.value;
1189
1190 /* and the number of entries */
1191 count = stop - start;
1192
1193 /* and copy out */
1194 if (startp)
1195 *startp = start;
1196 if (stopp)
1197 *stopp = stop;
1198 if (countp)
1199 *countp = count;
1200
1201 out:
1202 free(setsym, M_LINKER);
1203 return error;
1204 }
1205
1206 static int
1207 link_elf_each_function_name(linker_file_t file,
1208 int (*callback)(const char *, void *), void *opaque) {
1209 elf_file_t ef = (elf_file_t)file;
1210 const Elf_Sym* symp;
1211 int i, error;
1212
1213 /* Exhaustive search */
1214 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1215 if (symp->st_value != 0 &&
1216 ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1217 error = callback(ef->ddbstrtab + symp->st_name, opaque);
1218 if (error)
1219 return (error);
1220 }
1221 }
1222 return (0);
1223 }
1224
1225 #ifdef __ia64__
1226 /*
1227 * Each KLD has its own GP. The GP value for each load module is given by
1228 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
1229 * don't have direct access to the ELF file structure. The link_elf_get_gp()
1230 * function returns the GP given a pointer to a generic linker file struct.
1231 */
1232 Elf_Addr
1233 link_elf_get_gp(linker_file_t lf)
1234 {
1235 elf_file_t ef = (elf_file_t)lf;
1236 return (Elf_Addr)ef->got;
1237 }
1238 #endif
1239
1240 const Elf_Sym *
1241 elf_get_sym(linker_file_t lf, Elf_Size symidx)
1242 {
1243 elf_file_t ef = (elf_file_t)lf;
1244
1245 if (symidx >= ef->nchains)
1246 return (NULL);
1247 return (ef->symtab + symidx);
1248 }
1249
1250 const char *
1251 elf_get_symname(linker_file_t lf, Elf_Size symidx)
1252 {
1253 elf_file_t ef = (elf_file_t)lf;
1254 const Elf_Sym *sym;
1255
1256 if (symidx >= ef->nchains)
1257 return (NULL);
1258 sym = ef->symtab + symidx;
1259 return (ef->strtab + sym->st_name);
1260 }
1261
1262 /*
1263 * Symbol lookup function that can be used when the symbol index is known (ie
1264 * in relocations). It uses the symbol index instead of doing a fully fledged
1265 * hash table based lookup when such is valid. For example for local symbols.
1266 * This is not only more efficient, it's also more correct. It's not always
1267 * the case that the symbol can be found through the hash table.
1268 */
1269 static Elf_Addr
1270 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
1271 {
1272 elf_file_t ef = (elf_file_t)lf;
1273 const Elf_Sym *sym;
1274 const char *symbol;
1275
1276 /* Don't even try to lookup the symbol if the index is bogus. */
1277 if (symidx >= ef->nchains)
1278 return (0);
1279
1280 sym = ef->symtab + symidx;
1281
1282 /*
1283 * Don't do a full lookup when the symbol is local. It may even
1284 * fail because it may not be found through the hash table.
1285 */
1286 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1287 /* Force lookup failure when we have an insanity. */
1288 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1289 return (0);
1290 return ((Elf_Addr)ef->address + sym->st_value);
1291 }
1292
1293 /*
1294 * XXX we can avoid doing a hash table based lookup for global
1295 * symbols as well. This however is not always valid, so we'll
1296 * just do it the hard way for now. Performance tweaks can
1297 * always be added.
1298 */
1299
1300 symbol = ef->strtab + sym->st_name;
1301
1302 /* Force a lookup failure if the symbol name is bogus. */
1303 if (*symbol == 0)
1304 return (0);
1305
1306 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1307 }
1308
1309 static void
1310 link_elf_reloc_local(linker_file_t lf)
1311 {
1312 const Elf_Rel *rellim;
1313 const Elf_Rel *rel;
1314 const Elf_Rela *relalim;
1315 const Elf_Rela *rela;
1316 elf_file_t ef = (elf_file_t)lf;
1317
1318 /* Perform relocations without addend if there are any: */
1319 if ((rel = ef->rel) != NULL) {
1320 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1321 while (rel < rellim) {
1322 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
1323 elf_lookup);
1324 rel++;
1325 }
1326 }
1327
1328 /* Perform relocations with addend if there are any: */
1329 if ((rela = ef->rela) != NULL) {
1330 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
1331 while (rela < relalim) {
1332 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
1333 elf_lookup);
1334 rela++;
1335 }
1336 }
1337 }
Cache object: 45b414fe59b06d05177ab74e3016e05f
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