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/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_Word 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 vm_object_reference(ef->object);
708 ef->address = (caddr_t) vm_map_min(kernel_map);
709 error = vm_map_find(kernel_map, ef->object, 0,
710 (vm_offset_t *) &ef->address,
711 mapsize, 1,
712 VM_PROT_ALL, VM_PROT_ALL, 0);
713 #ifdef SPARSE_MAPPING
714 /*
715 * Wire down the pages
716 */
717 if (error == 0)
718 error = vm_map_wire(kernel_map, (vm_offset_t) ef->address,
719 (vm_offset_t) ef->address + mapsize,
720 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
721 #endif
722 if (error) {
723 vm_object_deallocate(ef->object);
724 ef->object = 0;
725 goto out;
726 }
727 #else
728 ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
729 if (!ef->address) {
730 error = ENOMEM;
731 goto out;
732 }
733 #endif
734 mapbase = ef->address;
735
736 /*
737 * Read the text and data sections and zero the bss.
738 */
739 for (i = 0; i < 2; i++) {
740 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
741 error = vn_rdwr(UIO_READ, nd.ni_vp,
742 segbase, segs[i]->p_filesz, segs[i]->p_offset,
743 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
744 &resid, td);
745 if (error) {
746 goto out;
747 }
748 bzero(segbase + segs[i]->p_filesz,
749 segs[i]->p_memsz - segs[i]->p_filesz);
750 }
751
752 #ifdef GPROF
753 /* Update profiling information with the new text segment. */
754 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
755 segs[0]->p_memsz));
756 #endif
757
758 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
759
760 lf->address = ef->address;
761 lf->size = mapsize;
762
763 error = parse_dynamic(ef);
764 if (error)
765 goto out;
766 link_elf_reloc_local(lf);
767
768 error = linker_load_dependencies(lf);
769 if (error)
770 goto out;
771 #if 0 /* this will be more trouble than it's worth for now */
772 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
773 if (dp->d_tag != DT_NEEDED)
774 continue;
775 modname = ef->strtab + dp->d_un.d_val;
776 error = linker_load_module(modname, lf);
777 if (error)
778 goto out;
779 }
780 #endif
781 error = relocate_file(ef);
782 if (error)
783 goto out;
784
785 /* Try and load the symbol table if it's present. (you can strip it!) */
786 nbytes = hdr->e_shnum * hdr->e_shentsize;
787 if (nbytes == 0 || hdr->e_shoff == 0)
788 goto nosyms;
789 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
790 if (shdr == NULL) {
791 error = ENOMEM;
792 goto out;
793 }
794 error = vn_rdwr(UIO_READ, nd.ni_vp,
795 (caddr_t)shdr, nbytes, hdr->e_shoff,
796 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
797 &resid, td);
798 if (error)
799 goto out;
800 symtabindex = -1;
801 symstrindex = -1;
802 for (i = 0; i < hdr->e_shnum; i++) {
803 if (shdr[i].sh_type == SHT_SYMTAB) {
804 symtabindex = i;
805 symstrindex = shdr[i].sh_link;
806 }
807 }
808 if (symtabindex < 0 || symstrindex < 0)
809 goto nosyms;
810
811 symcnt = shdr[symtabindex].sh_size;
812 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
813 strcnt = shdr[symstrindex].sh_size;
814 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
815
816 if (ef->symbase == NULL || ef->strbase == NULL) {
817 error = ENOMEM;
818 goto out;
819 }
820 error = vn_rdwr(UIO_READ, nd.ni_vp,
821 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
822 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
823 &resid, td);
824 if (error)
825 goto out;
826 error = vn_rdwr(UIO_READ, nd.ni_vp,
827 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
828 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
829 &resid, td);
830 if (error)
831 goto out;
832
833 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
834 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
835 ef->ddbstrcnt = strcnt;
836 ef->ddbstrtab = ef->strbase;
837
838 error = link_elf_link_common_finish(lf);
839 if (error)
840 goto out;
841
842 nosyms:
843
844 *result = lf;
845
846 out:
847 if (error && lf)
848 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
849 if (shdr)
850 free(shdr, M_LINKER);
851 if (firstpage)
852 free(firstpage, M_LINKER);
853 VOP_UNLOCK(nd.ni_vp, 0, td);
854 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
855
856 return error;
857 }
858
859 static void
860 link_elf_unload_file(linker_file_t file)
861 {
862 elf_file_t ef = (elf_file_t) file;
863
864 #ifdef GDB
865 if (ef->gdb.l_ld) {
866 GDB_STATE(RT_DELETE);
867 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
868 link_elf_delete_gdb(&ef->gdb);
869 GDB_STATE(RT_CONSISTENT);
870 }
871 #endif
872
873 /* Notify MD code that a module is being unloaded. */
874 elf_cpu_unload_file(file);
875
876 if (ef->preloaded) {
877 link_elf_unload_preload(file);
878 return;
879 }
880
881 #ifdef SPARSE_MAPPING
882 if (ef->object) {
883 /*
884 * Unwire the pages
885 */
886 vm_map_unwire(kernel_map,
887 (vm_offset_t) ef->address,
888 (vm_offset_t) ef->address
889 + (ef->object->size << PAGE_SHIFT),
890 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
891 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
892 (vm_offset_t) ef->address
893 + (ef->object->size << PAGE_SHIFT));
894 vm_object_deallocate(ef->object);
895 }
896 #else
897 if (ef->address)
898 free(ef->address, M_LINKER);
899 #endif
900 if (ef->symbase)
901 free(ef->symbase, M_LINKER);
902 if (ef->strbase)
903 free(ef->strbase, M_LINKER);
904 }
905
906 static void
907 link_elf_unload_preload(linker_file_t file)
908 {
909 if (file->filename)
910 preload_delete_name(file->filename);
911 }
912
913 static const char *
914 symbol_name(elf_file_t ef, Elf_Word r_info)
915 {
916 const Elf_Sym *ref;
917
918 if (ELF_R_SYM(r_info)) {
919 ref = ef->symtab + ELF_R_SYM(r_info);
920 return ef->strtab + ref->st_name;
921 } else
922 return NULL;
923 }
924
925 static int
926 relocate_file(elf_file_t ef)
927 {
928 const Elf_Rel *rellim;
929 const Elf_Rel *rel;
930 const Elf_Rela *relalim;
931 const Elf_Rela *rela;
932 const char *symname;
933
934 /* Perform relocations without addend if there are any: */
935 rel = ef->rel;
936 if (rel) {
937 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
938 while (rel < rellim) {
939 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
940 elf_lookup)) {
941 symname = symbol_name(ef, rel->r_info);
942 printf("link_elf: symbol %s undefined\n", symname);
943 return ENOENT;
944 }
945 rel++;
946 }
947 }
948
949 /* Perform relocations with addend if there are any: */
950 rela = ef->rela;
951 if (rela) {
952 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
953 while (rela < relalim) {
954 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
955 elf_lookup)) {
956 symname = symbol_name(ef, rela->r_info);
957 printf("link_elf: symbol %s undefined\n", symname);
958 return ENOENT;
959 }
960 rela++;
961 }
962 }
963
964 /* Perform PLT relocations without addend if there are any: */
965 rel = ef->pltrel;
966 if (rel) {
967 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
968 while (rel < rellim) {
969 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
970 elf_lookup)) {
971 symname = symbol_name(ef, rel->r_info);
972 printf("link_elf: symbol %s undefined\n", symname);
973 return ENOENT;
974 }
975 rel++;
976 }
977 }
978
979 /* Perform relocations with addend if there are any: */
980 rela = ef->pltrela;
981 if (rela) {
982 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
983 while (rela < relalim) {
984 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
985 elf_lookup)) {
986 symname = symbol_name(ef, rela->r_info);
987 printf("link_elf: symbol %s undefined\n", symname);
988 return ENOENT;
989 }
990 rela++;
991 }
992 }
993
994 return 0;
995 }
996
997 /*
998 * Hash function for symbol table lookup. Don't even think about changing
999 * this. It is specified by the System V ABI.
1000 */
1001 static unsigned long
1002 elf_hash(const char *name)
1003 {
1004 const unsigned char *p = (const unsigned char *) name;
1005 unsigned long h = 0;
1006 unsigned long g;
1007
1008 while (*p != '\0') {
1009 h = (h << 4) + *p++;
1010 if ((g = h & 0xf0000000) != 0)
1011 h ^= g >> 24;
1012 h &= ~g;
1013 }
1014 return h;
1015 }
1016
1017 static int
1018 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
1019 {
1020 elf_file_t ef = (elf_file_t) lf;
1021 unsigned long symnum;
1022 const Elf_Sym* symp;
1023 const char *strp;
1024 unsigned long hash;
1025 int i;
1026
1027 /* If we don't have a hash, bail. */
1028 if (ef->buckets == NULL || ef->nbuckets == 0) {
1029 printf("link_elf_lookup_symbol: missing symbol hash table\n");
1030 return ENOENT;
1031 }
1032
1033 /* First, search hashed global symbols */
1034 hash = elf_hash(name);
1035 symnum = ef->buckets[hash % ef->nbuckets];
1036
1037 while (symnum != STN_UNDEF) {
1038 if (symnum >= ef->nchains) {
1039 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1040 return ENOENT;
1041 }
1042
1043 symp = ef->symtab + symnum;
1044 if (symp->st_name == 0) {
1045 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1046 return ENOENT;
1047 }
1048
1049 strp = ef->strtab + symp->st_name;
1050
1051 if (strcmp(name, strp) == 0) {
1052 if (symp->st_shndx != SHN_UNDEF ||
1053 (symp->st_value != 0 &&
1054 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1055 *sym = (c_linker_sym_t) symp;
1056 return 0;
1057 } else
1058 return ENOENT;
1059 }
1060
1061 symnum = ef->chains[symnum];
1062 }
1063
1064 /* If we have not found it, look at the full table (if loaded) */
1065 if (ef->symtab == ef->ddbsymtab)
1066 return ENOENT;
1067
1068 /* Exhaustive search */
1069 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1070 strp = ef->ddbstrtab + symp->st_name;
1071 if (strcmp(name, strp) == 0) {
1072 if (symp->st_shndx != SHN_UNDEF ||
1073 (symp->st_value != 0 &&
1074 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1075 *sym = (c_linker_sym_t) symp;
1076 return 0;
1077 } else
1078 return ENOENT;
1079 }
1080 }
1081
1082 return ENOENT;
1083 }
1084
1085 static int
1086 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1087 {
1088 elf_file_t ef = (elf_file_t) lf;
1089 const Elf_Sym* es = (const Elf_Sym*) sym;
1090
1091 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1092 symval->name = ef->strtab + es->st_name;
1093 symval->value = (caddr_t) ef->address + es->st_value;
1094 symval->size = es->st_size;
1095 return 0;
1096 }
1097 if (ef->symtab == ef->ddbsymtab)
1098 return ENOENT;
1099 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1100 symval->name = ef->ddbstrtab + es->st_name;
1101 symval->value = (caddr_t) ef->address + es->st_value;
1102 symval->size = es->st_size;
1103 return 0;
1104 }
1105 return ENOENT;
1106 }
1107
1108 static int
1109 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1110 c_linker_sym_t* sym, long* diffp)
1111 {
1112 elf_file_t ef = (elf_file_t) lf;
1113 u_long off = (uintptr_t) (void *) value;
1114 u_long diff = off;
1115 u_long st_value;
1116 const Elf_Sym* es;
1117 const Elf_Sym* best = 0;
1118 int i;
1119
1120 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1121 if (es->st_name == 0)
1122 continue;
1123 st_value = es->st_value + (uintptr_t) (void *) ef->address;
1124 if (off >= st_value) {
1125 if (off - st_value < diff) {
1126 diff = off - st_value;
1127 best = es;
1128 if (diff == 0)
1129 break;
1130 } else if (off - st_value == diff) {
1131 best = es;
1132 }
1133 }
1134 }
1135 if (best == 0)
1136 *diffp = off;
1137 else
1138 *diffp = diff;
1139 *sym = (c_linker_sym_t) best;
1140
1141 return 0;
1142 }
1143
1144 /*
1145 * Look up a linker set on an ELF system.
1146 */
1147 static int
1148 link_elf_lookup_set(linker_file_t lf, const char *name,
1149 void ***startp, void ***stopp, int *countp)
1150 {
1151 c_linker_sym_t sym;
1152 linker_symval_t symval;
1153 char *setsym;
1154 void **start, **stop;
1155 int len, error = 0, count;
1156
1157 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1158 setsym = malloc(len, M_LINKER, M_WAITOK);
1159 if (setsym == NULL)
1160 return ENOMEM;
1161
1162 /* get address of first entry */
1163 snprintf(setsym, len, "%s%s", "__start_set_", name);
1164 error = link_elf_lookup_symbol(lf, setsym, &sym);
1165 if (error)
1166 goto out;
1167 link_elf_symbol_values(lf, sym, &symval);
1168 if (symval.value == 0) {
1169 error = ESRCH;
1170 goto out;
1171 }
1172 start = (void **)symval.value;
1173
1174 /* get address of last entry */
1175 snprintf(setsym, len, "%s%s", "__stop_set_", name);
1176 error = link_elf_lookup_symbol(lf, setsym, &sym);
1177 if (error)
1178 goto out;
1179 link_elf_symbol_values(lf, sym, &symval);
1180 if (symval.value == 0) {
1181 error = ESRCH;
1182 goto out;
1183 }
1184 stop = (void **)symval.value;
1185
1186 /* and the number of entries */
1187 count = stop - start;
1188
1189 /* and copy out */
1190 if (startp)
1191 *startp = start;
1192 if (stopp)
1193 *stopp = stop;
1194 if (countp)
1195 *countp = count;
1196
1197 out:
1198 free(setsym, M_LINKER);
1199 return error;
1200 }
1201
1202 static int
1203 link_elf_each_function_name(linker_file_t file,
1204 int (*callback)(const char *, void *), void *opaque) {
1205 elf_file_t ef = (elf_file_t)file;
1206 const Elf_Sym* symp;
1207 int i, error;
1208
1209 /* Exhaustive search */
1210 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1211 if (symp->st_value != 0 &&
1212 ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1213 error = callback(ef->ddbstrtab + symp->st_name, opaque);
1214 if (error)
1215 return (error);
1216 }
1217 }
1218 return (0);
1219 }
1220
1221 #ifdef __ia64__
1222 /*
1223 * Each KLD has its own GP. The GP value for each load module is given by
1224 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
1225 * don't have direct access to the ELF file structure. The link_elf_get_gp()
1226 * function returns the GP given a pointer to a generic linker file struct.
1227 */
1228 Elf_Addr
1229 link_elf_get_gp(linker_file_t lf)
1230 {
1231 elf_file_t ef = (elf_file_t)lf;
1232 return (Elf_Addr)ef->got;
1233 }
1234 #endif
1235
1236 const Elf_Sym *
1237 elf_get_sym(linker_file_t lf, Elf_Word symidx)
1238 {
1239 elf_file_t ef = (elf_file_t)lf;
1240
1241 if (symidx >= ef->nchains)
1242 return (NULL);
1243 return (ef->symtab + symidx);
1244 }
1245
1246 const char *
1247 elf_get_symname(linker_file_t lf, Elf_Word symidx)
1248 {
1249 elf_file_t ef = (elf_file_t)lf;
1250 const Elf_Sym *sym;
1251
1252 if (symidx >= ef->nchains)
1253 return (NULL);
1254 sym = ef->symtab + symidx;
1255 return (ef->strtab + sym->st_name);
1256 }
1257
1258 /*
1259 * Symbol lookup function that can be used when the symbol index is known (ie
1260 * in relocations). It uses the symbol index instead of doing a fully fledged
1261 * hash table based lookup when such is valid. For example for local symbols.
1262 * This is not only more efficient, it's also more correct. It's not always
1263 * the case that the symbol can be found through the hash table.
1264 */
1265 static Elf_Addr
1266 elf_lookup(linker_file_t lf, Elf_Word symidx, int deps)
1267 {
1268 elf_file_t ef = (elf_file_t)lf;
1269 const Elf_Sym *sym;
1270 const char *symbol;
1271
1272 /* Don't even try to lookup the symbol if the index is bogus. */
1273 if (symidx >= ef->nchains)
1274 return (0);
1275
1276 sym = ef->symtab + symidx;
1277
1278 /*
1279 * Don't do a full lookup when the symbol is local. It may even
1280 * fail because it may not be found through the hash table.
1281 */
1282 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1283 /* Force lookup failure when we have an insanity. */
1284 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1285 return (0);
1286 return ((Elf_Addr)ef->address + sym->st_value);
1287 }
1288
1289 /*
1290 * XXX we can avoid doing a hash table based lookup for global
1291 * symbols as well. This however is not always valid, so we'll
1292 * just do it the hard way for now. Performance tweaks can
1293 * always be added.
1294 */
1295
1296 symbol = ef->strtab + sym->st_name;
1297
1298 /* Force a lookup failure if the symbol name is bogus. */
1299 if (*symbol == 0)
1300 return (0);
1301
1302 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1303 }
1304
1305 static void
1306 link_elf_reloc_local(linker_file_t lf)
1307 {
1308 const Elf_Rel *rellim;
1309 const Elf_Rel *rel;
1310 const Elf_Rela *relalim;
1311 const Elf_Rela *rela;
1312 elf_file_t ef = (elf_file_t)lf;
1313
1314 /* Perform relocations without addend if there are any: */
1315 if ((rel = ef->rel) != NULL) {
1316 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1317 while (rel < rellim) {
1318 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
1319 elf_lookup);
1320 rel++;
1321 }
1322 }
1323
1324 /* Perform relocations with addend if there are any: */
1325 if ((rela = ef->rela) != NULL) {
1326 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
1327 while (rela < relalim) {
1328 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
1329 elf_lookup);
1330 rela++;
1331 }
1332 }
1333 }
Cache object: fa37fad0a3eb6760ae62b9a5f231c059
|