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 #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 *filename, const char *s)
217 {
218 if (filename == NULL)
219 printf("kldload: %s\n", s);
220 else
221 printf("kldload: %s: %s\n", filename, s);
222 }
223
224 /*
225 * Actions performed after linking/loading both the preloaded kernel and any
226 * modules; whether preloaded or dynamicly loaded.
227 */
228 static int
229 link_elf_link_common_finish(linker_file_t lf)
230 {
231 #ifdef GDB
232 elf_file_t ef = (elf_file_t)lf;
233 char *newfilename;
234 #endif
235 int error;
236
237 /* Notify MD code that a module is being loaded. */
238 error = elf_cpu_load_file(lf);
239 if (error)
240 return (error);
241
242 #ifdef GDB
243 GDB_STATE(RT_ADD);
244 ef->gdb.l_addr = lf->address;
245 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
246 strcpy(newfilename, lf->filename);
247 ef->gdb.l_name = newfilename;
248 ef->gdb.l_ld = ef->dynamic;
249 link_elf_add_gdb(&ef->gdb);
250 GDB_STATE(RT_CONSISTENT);
251 #endif
252
253 return (0);
254 }
255
256 static void
257 link_elf_init(void* arg)
258 {
259 Elf_Dyn *dp;
260 caddr_t modptr, baseptr, sizeptr;
261 elf_file_t ef;
262 char *modname;
263
264 linker_add_class(&link_elf_class);
265
266 dp = (Elf_Dyn*) &_DYNAMIC;
267 modname = NULL;
268 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
269 if (modptr == NULL)
270 modptr = preload_search_by_type("elf kernel");
271 if (modptr)
272 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
273 if (modname == NULL)
274 modname = "kernel";
275 linker_kernel_file = linker_make_file(modname, &link_elf_class);
276 if (linker_kernel_file == NULL)
277 panic("link_elf_init: Can't create linker structures for kernel");
278
279 ef = (elf_file_t) linker_kernel_file;
280 ef->preloaded = 1;
281 ef->address = 0;
282 #ifdef SPARSE_MAPPING
283 ef->object = 0;
284 #endif
285 ef->dynamic = dp;
286
287 if (dp)
288 parse_dynamic(ef);
289 linker_kernel_file->address = (caddr_t) KERNBASE;
290 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
291
292 if (modptr) {
293 ef->modptr = modptr;
294 baseptr = preload_search_info(modptr, MODINFO_ADDR);
295 if (baseptr)
296 linker_kernel_file->address = *(caddr_t *)baseptr;
297 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
298 if (sizeptr)
299 linker_kernel_file->size = *(size_t *)sizeptr;
300 }
301 (void)link_elf_preload_parse_symbols(ef);
302
303 #ifdef GDB
304 r_debug.r_map = NULL;
305 r_debug.r_brk = r_debug_state;
306 r_debug.r_state = RT_CONSISTENT;
307 #endif
308
309 (void)link_elf_link_common_finish(linker_kernel_file);
310 }
311
312 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, 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
563 GIANT_REQUIRED;
564
565 shdr = NULL;
566 lf = NULL;
567
568 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
569 flags = FREAD;
570 error = vn_open(&nd, &flags, 0, -1);
571 if (error)
572 return error;
573 NDFREE(&nd, NDF_ONLY_PNBUF);
574 if (nd.ni_vp->v_type != VREG) {
575 error = ENOEXEC;
576 firstpage = NULL;
577 goto out;
578 }
579 #ifdef MAC
580 error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp);
581 if (error) {
582 firstpage = NULL;
583 goto out;
584 }
585 #endif
586
587 /*
588 * Read the elf header from the file.
589 */
590 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
591 if (firstpage == NULL) {
592 error = ENOMEM;
593 goto out;
594 }
595 hdr = (Elf_Ehdr *)firstpage;
596 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
597 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
598 &resid, td);
599 nbytes = PAGE_SIZE - resid;
600 if (error)
601 goto out;
602
603 if (!IS_ELF(*hdr)) {
604 error = ENOEXEC;
605 goto out;
606 }
607
608 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
609 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
610 link_elf_error(filename, "Unsupported file layout");
611 error = ENOEXEC;
612 goto out;
613 }
614 if (hdr->e_ident[EI_VERSION] != EV_CURRENT
615 || hdr->e_version != EV_CURRENT) {
616 link_elf_error(filename, "Unsupported file version");
617 error = ENOEXEC;
618 goto out;
619 }
620 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
621 link_elf_error(filename, "Unsupported file type");
622 error = ENOEXEC;
623 goto out;
624 }
625 if (hdr->e_machine != ELF_TARG_MACH) {
626 link_elf_error(filename, "Unsupported machine");
627 error = ENOEXEC;
628 goto out;
629 }
630
631 /*
632 * We rely on the program header being in the first page. This is
633 * not strictly required by the ABI specification, but it seems to
634 * always true in practice. And, it simplifies things considerably.
635 */
636 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
637 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
638 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
639 link_elf_error(filename, "Unreadable program headers");
640
641 /*
642 * Scan the program header entries, and save key information.
643 *
644 * We rely on there being exactly two load segments, text and data,
645 * in that order.
646 */
647 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
648 phlimit = phdr + hdr->e_phnum;
649 nsegs = 0;
650 phdyn = NULL;
651 phphdr = NULL;
652 while (phdr < phlimit) {
653 switch (phdr->p_type) {
654
655 case PT_LOAD:
656 if (nsegs == MAXSEGS) {
657 link_elf_error(filename, "Too many sections");
658 error = ENOEXEC;
659 goto out;
660 }
661 /*
662 * XXX: We just trust they come in right order ??
663 */
664 segs[nsegs] = phdr;
665 ++nsegs;
666 break;
667
668 case PT_PHDR:
669 phphdr = phdr;
670 break;
671
672 case PT_DYNAMIC:
673 phdyn = phdr;
674 break;
675
676 case PT_INTERP:
677 link_elf_error(filename, "Unsupported file type");
678 error = ENOEXEC;
679 goto out;
680 }
681
682 ++phdr;
683 }
684 if (phdyn == NULL) {
685 link_elf_error(filename, "Object is not dynamically-linked");
686 error = ENOEXEC;
687 goto out;
688 }
689 if (nsegs == 0) {
690 link_elf_error(filename, "No sections");
691 error = ENOEXEC;
692 goto out;
693 }
694
695 /*
696 * Allocate the entire address space of the object, to stake out our
697 * contiguous region, and to establish the base address for relocation.
698 */
699 base_offset = trunc_page(segs[0]->p_offset);
700 base_vaddr = trunc_page(segs[0]->p_vaddr);
701 base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
702 segs[nsegs - 1]->p_memsz);
703 mapsize = base_vlimit - base_vaddr;
704
705 lf = linker_make_file(filename, &link_elf_class);
706 if (!lf) {
707 error = ENOMEM;
708 goto out;
709 }
710
711 ef = (elf_file_t) lf;
712 #ifdef SPARSE_MAPPING
713 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
714 if (ef->object == NULL) {
715 error = ENOMEM;
716 goto out;
717 }
718 ef->address = (caddr_t) vm_map_min(kernel_map);
719 error = vm_map_find(kernel_map, ef->object, 0,
720 (vm_offset_t *) &ef->address,
721 mapsize, 1,
722 VM_PROT_ALL, VM_PROT_ALL, 0);
723 if (error) {
724 vm_object_deallocate(ef->object);
725 ef->object = 0;
726 goto out;
727 }
728 #else
729 ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
730 if (!ef->address) {
731 error = ENOMEM;
732 goto out;
733 }
734 #endif
735 mapbase = ef->address;
736
737 /*
738 * Read the text and data sections and zero the bss.
739 */
740 for (i = 0; i < nsegs; i++) {
741 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
742 error = vn_rdwr(UIO_READ, nd.ni_vp,
743 segbase, segs[i]->p_filesz, segs[i]->p_offset,
744 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
745 &resid, td);
746 if (error) {
747 goto out;
748 }
749 bzero(segbase + segs[i]->p_filesz,
750 segs[i]->p_memsz - segs[i]->p_filesz);
751
752 #ifdef SPARSE_MAPPING
753 /*
754 * Wire down the pages
755 */
756 error = vm_map_wire(kernel_map,
757 (vm_offset_t) segbase,
758 (vm_offset_t) segbase + segs[i]->p_memsz,
759 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
760 if (error != KERN_SUCCESS) {
761 error = ENOMEM;
762 goto out;
763 }
764 #endif
765 }
766
767 #ifdef GPROF
768 /* Update profiling information with the new text segment. */
769 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
770 segs[0]->p_memsz));
771 #endif
772
773 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
774
775 lf->address = ef->address;
776 lf->size = mapsize;
777
778 error = parse_dynamic(ef);
779 if (error)
780 goto out;
781 link_elf_reloc_local(lf);
782
783 error = linker_load_dependencies(lf);
784 if (error)
785 goto out;
786 #if 0 /* this will be more trouble than it's worth for now */
787 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
788 if (dp->d_tag != DT_NEEDED)
789 continue;
790 modname = ef->strtab + dp->d_un.d_val;
791 error = linker_load_module(modname, lf);
792 if (error)
793 goto out;
794 }
795 #endif
796 error = relocate_file(ef);
797 if (error)
798 goto out;
799
800 /* Try and load the symbol table if it's present. (you can strip it!) */
801 nbytes = hdr->e_shnum * hdr->e_shentsize;
802 if (nbytes == 0 || hdr->e_shoff == 0)
803 goto nosyms;
804 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
805 if (shdr == NULL) {
806 error = ENOMEM;
807 goto out;
808 }
809 error = vn_rdwr(UIO_READ, nd.ni_vp,
810 (caddr_t)shdr, nbytes, hdr->e_shoff,
811 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
812 &resid, td);
813 if (error)
814 goto out;
815 symtabindex = -1;
816 symstrindex = -1;
817 for (i = 0; i < hdr->e_shnum; i++) {
818 if (shdr[i].sh_type == SHT_SYMTAB) {
819 symtabindex = i;
820 symstrindex = shdr[i].sh_link;
821 }
822 }
823 if (symtabindex < 0 || symstrindex < 0)
824 goto nosyms;
825
826 symcnt = shdr[symtabindex].sh_size;
827 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
828 strcnt = shdr[symstrindex].sh_size;
829 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
830
831 if (ef->symbase == NULL || ef->strbase == NULL) {
832 error = ENOMEM;
833 goto out;
834 }
835 error = vn_rdwr(UIO_READ, nd.ni_vp,
836 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
837 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
838 &resid, td);
839 if (error)
840 goto out;
841 error = vn_rdwr(UIO_READ, nd.ni_vp,
842 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
843 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
844 &resid, td);
845 if (error)
846 goto out;
847
848 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
849 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
850 ef->ddbstrcnt = strcnt;
851 ef->ddbstrtab = ef->strbase;
852
853 error = link_elf_link_common_finish(lf);
854 if (error)
855 goto out;
856
857 nosyms:
858
859 *result = lf;
860
861 out:
862 if (error && lf)
863 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
864 if (shdr)
865 free(shdr, M_LINKER);
866 if (firstpage)
867 free(firstpage, M_LINKER);
868 VOP_UNLOCK(nd.ni_vp, 0, td);
869 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
870
871 return error;
872 }
873
874 static void
875 link_elf_unload_file(linker_file_t file)
876 {
877 elf_file_t ef = (elf_file_t) file;
878
879 #ifdef GDB
880 if (ef->gdb.l_ld) {
881 GDB_STATE(RT_DELETE);
882 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
883 link_elf_delete_gdb(&ef->gdb);
884 GDB_STATE(RT_CONSISTENT);
885 }
886 #endif
887
888 /* Notify MD code that a module is being unloaded. */
889 elf_cpu_unload_file(file);
890
891 if (ef->preloaded) {
892 link_elf_unload_preload(file);
893 return;
894 }
895
896 #ifdef SPARSE_MAPPING
897 if (ef->object) {
898 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
899 (vm_offset_t) ef->address
900 + (ef->object->size << PAGE_SHIFT));
901 }
902 #else
903 if (ef->address)
904 free(ef->address, M_LINKER);
905 #endif
906 if (ef->symbase)
907 free(ef->symbase, M_LINKER);
908 if (ef->strbase)
909 free(ef->strbase, M_LINKER);
910 }
911
912 static void
913 link_elf_unload_preload(linker_file_t file)
914 {
915 if (file->filename)
916 preload_delete_name(file->filename);
917 }
918
919 static const char *
920 symbol_name(elf_file_t ef, Elf_Size r_info)
921 {
922 const Elf_Sym *ref;
923
924 if (ELF_R_SYM(r_info)) {
925 ref = ef->symtab + ELF_R_SYM(r_info);
926 return ef->strtab + ref->st_name;
927 } else
928 return NULL;
929 }
930
931 static int
932 relocate_file(elf_file_t ef)
933 {
934 const Elf_Rel *rellim;
935 const Elf_Rel *rel;
936 const Elf_Rela *relalim;
937 const Elf_Rela *rela;
938 const char *symname;
939
940 /* Perform relocations without addend if there are any: */
941 rel = ef->rel;
942 if (rel) {
943 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
944 while (rel < rellim) {
945 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
946 elf_lookup)) {
947 symname = symbol_name(ef, rel->r_info);
948 printf("link_elf: symbol %s undefined\n", symname);
949 return ENOENT;
950 }
951 rel++;
952 }
953 }
954
955 /* Perform relocations with addend if there are any: */
956 rela = ef->rela;
957 if (rela) {
958 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
959 while (rela < relalim) {
960 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
961 elf_lookup)) {
962 symname = symbol_name(ef, rela->r_info);
963 printf("link_elf: symbol %s undefined\n", symname);
964 return ENOENT;
965 }
966 rela++;
967 }
968 }
969
970 /* Perform PLT relocations without addend if there are any: */
971 rel = ef->pltrel;
972 if (rel) {
973 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
974 while (rel < rellim) {
975 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
976 elf_lookup)) {
977 symname = symbol_name(ef, rel->r_info);
978 printf("link_elf: symbol %s undefined\n", symname);
979 return ENOENT;
980 }
981 rel++;
982 }
983 }
984
985 /* Perform relocations with addend if there are any: */
986 rela = ef->pltrela;
987 if (rela) {
988 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
989 while (rela < relalim) {
990 if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
991 elf_lookup)) {
992 symname = symbol_name(ef, rela->r_info);
993 printf("link_elf: symbol %s undefined\n", symname);
994 return ENOENT;
995 }
996 rela++;
997 }
998 }
999
1000 return 0;
1001 }
1002
1003 /*
1004 * Hash function for symbol table lookup. Don't even think about changing
1005 * this. It is specified by the System V ABI.
1006 */
1007 static unsigned long
1008 elf_hash(const char *name)
1009 {
1010 const unsigned char *p = (const unsigned char *) name;
1011 unsigned long h = 0;
1012 unsigned long g;
1013
1014 while (*p != '\0') {
1015 h = (h << 4) + *p++;
1016 if ((g = h & 0xf0000000) != 0)
1017 h ^= g >> 24;
1018 h &= ~g;
1019 }
1020 return h;
1021 }
1022
1023 static int
1024 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
1025 {
1026 elf_file_t ef = (elf_file_t) lf;
1027 unsigned long symnum;
1028 const Elf_Sym* symp;
1029 const char *strp;
1030 unsigned long hash;
1031 int i;
1032
1033 /* If we don't have a hash, bail. */
1034 if (ef->buckets == NULL || ef->nbuckets == 0) {
1035 printf("link_elf_lookup_symbol: missing symbol hash table\n");
1036 return ENOENT;
1037 }
1038
1039 /* First, search hashed global symbols */
1040 hash = elf_hash(name);
1041 symnum = ef->buckets[hash % ef->nbuckets];
1042
1043 while (symnum != STN_UNDEF) {
1044 if (symnum >= ef->nchains) {
1045 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1046 return ENOENT;
1047 }
1048
1049 symp = ef->symtab + symnum;
1050 if (symp->st_name == 0) {
1051 printf("link_elf_lookup_symbol: corrupt symbol table\n");
1052 return ENOENT;
1053 }
1054
1055 strp = ef->strtab + symp->st_name;
1056
1057 if (strcmp(name, strp) == 0) {
1058 if (symp->st_shndx != SHN_UNDEF ||
1059 (symp->st_value != 0 &&
1060 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1061 *sym = (c_linker_sym_t) symp;
1062 return 0;
1063 } else
1064 return ENOENT;
1065 }
1066
1067 symnum = ef->chains[symnum];
1068 }
1069
1070 /* If we have not found it, look at the full table (if loaded) */
1071 if (ef->symtab == ef->ddbsymtab)
1072 return ENOENT;
1073
1074 /* Exhaustive search */
1075 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1076 strp = ef->ddbstrtab + symp->st_name;
1077 if (strcmp(name, strp) == 0) {
1078 if (symp->st_shndx != SHN_UNDEF ||
1079 (symp->st_value != 0 &&
1080 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1081 *sym = (c_linker_sym_t) symp;
1082 return 0;
1083 } else
1084 return ENOENT;
1085 }
1086 }
1087
1088 return ENOENT;
1089 }
1090
1091 static int
1092 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1093 {
1094 elf_file_t ef = (elf_file_t) lf;
1095 const Elf_Sym* es = (const Elf_Sym*) sym;
1096
1097 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1098 symval->name = ef->strtab + es->st_name;
1099 symval->value = (caddr_t) ef->address + es->st_value;
1100 symval->size = es->st_size;
1101 return 0;
1102 }
1103 if (ef->symtab == ef->ddbsymtab)
1104 return ENOENT;
1105 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1106 symval->name = ef->ddbstrtab + es->st_name;
1107 symval->value = (caddr_t) ef->address + es->st_value;
1108 symval->size = es->st_size;
1109 return 0;
1110 }
1111 return ENOENT;
1112 }
1113
1114 static int
1115 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1116 c_linker_sym_t* sym, long* diffp)
1117 {
1118 elf_file_t ef = (elf_file_t) lf;
1119 u_long off = (uintptr_t) (void *) value;
1120 u_long diff = off;
1121 u_long st_value;
1122 const Elf_Sym* es;
1123 const Elf_Sym* best = 0;
1124 int i;
1125
1126 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1127 if (es->st_name == 0)
1128 continue;
1129 st_value = es->st_value + (uintptr_t) (void *) ef->address;
1130 if (off >= st_value) {
1131 if (off - st_value < diff) {
1132 diff = off - st_value;
1133 best = es;
1134 if (diff == 0)
1135 break;
1136 } else if (off - st_value == diff) {
1137 best = es;
1138 }
1139 }
1140 }
1141 if (best == 0)
1142 *diffp = off;
1143 else
1144 *diffp = diff;
1145 *sym = (c_linker_sym_t) best;
1146
1147 return 0;
1148 }
1149
1150 /*
1151 * Look up a linker set on an ELF system.
1152 */
1153 static int
1154 link_elf_lookup_set(linker_file_t lf, const char *name,
1155 void ***startp, void ***stopp, int *countp)
1156 {
1157 c_linker_sym_t sym;
1158 linker_symval_t symval;
1159 char *setsym;
1160 void **start, **stop;
1161 int len, error = 0, count;
1162
1163 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1164 setsym = malloc(len, M_LINKER, M_WAITOK);
1165 if (setsym == NULL)
1166 return ENOMEM;
1167
1168 /* get address of first entry */
1169 snprintf(setsym, len, "%s%s", "__start_set_", name);
1170 error = link_elf_lookup_symbol(lf, setsym, &sym);
1171 if (error)
1172 goto out;
1173 link_elf_symbol_values(lf, sym, &symval);
1174 if (symval.value == 0) {
1175 error = ESRCH;
1176 goto out;
1177 }
1178 start = (void **)symval.value;
1179
1180 /* get address of last entry */
1181 snprintf(setsym, len, "%s%s", "__stop_set_", name);
1182 error = link_elf_lookup_symbol(lf, setsym, &sym);
1183 if (error)
1184 goto out;
1185 link_elf_symbol_values(lf, sym, &symval);
1186 if (symval.value == 0) {
1187 error = ESRCH;
1188 goto out;
1189 }
1190 stop = (void **)symval.value;
1191
1192 /* and the number of entries */
1193 count = stop - start;
1194
1195 /* and copy out */
1196 if (startp)
1197 *startp = start;
1198 if (stopp)
1199 *stopp = stop;
1200 if (countp)
1201 *countp = count;
1202
1203 out:
1204 free(setsym, M_LINKER);
1205 return error;
1206 }
1207
1208 static int
1209 link_elf_each_function_name(linker_file_t file,
1210 int (*callback)(const char *, void *), void *opaque) {
1211 elf_file_t ef = (elf_file_t)file;
1212 const Elf_Sym* symp;
1213 int i, error;
1214
1215 /* Exhaustive search */
1216 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1217 if (symp->st_value != 0 &&
1218 ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1219 error = callback(ef->ddbstrtab + symp->st_name, opaque);
1220 if (error)
1221 return (error);
1222 }
1223 }
1224 return (0);
1225 }
1226
1227 #ifdef __ia64__
1228 /*
1229 * Each KLD has its own GP. The GP value for each load module is given by
1230 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
1231 * don't have direct access to the ELF file structure. The link_elf_get_gp()
1232 * function returns the GP given a pointer to a generic linker file struct.
1233 */
1234 Elf_Addr
1235 link_elf_get_gp(linker_file_t lf)
1236 {
1237 elf_file_t ef = (elf_file_t)lf;
1238 return (Elf_Addr)ef->got;
1239 }
1240 #endif
1241
1242 const Elf_Sym *
1243 elf_get_sym(linker_file_t lf, Elf_Size symidx)
1244 {
1245 elf_file_t ef = (elf_file_t)lf;
1246
1247 if (symidx >= ef->nchains)
1248 return (NULL);
1249 return (ef->symtab + symidx);
1250 }
1251
1252 const char *
1253 elf_get_symname(linker_file_t lf, Elf_Size symidx)
1254 {
1255 elf_file_t ef = (elf_file_t)lf;
1256 const Elf_Sym *sym;
1257
1258 if (symidx >= ef->nchains)
1259 return (NULL);
1260 sym = ef->symtab + symidx;
1261 return (ef->strtab + sym->st_name);
1262 }
1263
1264 /*
1265 * Symbol lookup function that can be used when the symbol index is known (ie
1266 * in relocations). It uses the symbol index instead of doing a fully fledged
1267 * hash table based lookup when such is valid. For example for local symbols.
1268 * This is not only more efficient, it's also more correct. It's not always
1269 * the case that the symbol can be found through the hash table.
1270 */
1271 static Elf_Addr
1272 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
1273 {
1274 elf_file_t ef = (elf_file_t)lf;
1275 const Elf_Sym *sym;
1276 const char *symbol;
1277
1278 /* Don't even try to lookup the symbol if the index is bogus. */
1279 if (symidx >= ef->nchains)
1280 return (0);
1281
1282 sym = ef->symtab + symidx;
1283
1284 /*
1285 * Don't do a full lookup when the symbol is local. It may even
1286 * fail because it may not be found through the hash table.
1287 */
1288 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1289 /* Force lookup failure when we have an insanity. */
1290 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1291 return (0);
1292 return ((Elf_Addr)ef->address + sym->st_value);
1293 }
1294
1295 /*
1296 * XXX we can avoid doing a hash table based lookup for global
1297 * symbols as well. This however is not always valid, so we'll
1298 * just do it the hard way for now. Performance tweaks can
1299 * always be added.
1300 */
1301
1302 symbol = ef->strtab + sym->st_name;
1303
1304 /* Force a lookup failure if the symbol name is bogus. */
1305 if (*symbol == 0)
1306 return (0);
1307
1308 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1309 }
1310
1311 static void
1312 link_elf_reloc_local(linker_file_t lf)
1313 {
1314 const Elf_Rel *rellim;
1315 const Elf_Rel *rel;
1316 const Elf_Rela *relalim;
1317 const Elf_Rela *rela;
1318 elf_file_t ef = (elf_file_t)lf;
1319
1320 /* Perform relocations without addend if there are any: */
1321 if ((rel = ef->rel) != NULL) {
1322 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1323 while (rel < rellim) {
1324 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
1325 elf_lookup);
1326 rel++;
1327 }
1328 }
1329
1330 /* Perform relocations with addend if there are any: */
1331 if ((rela = ef->rela) != NULL) {
1332 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
1333 while (rela < relalim) {
1334 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
1335 elf_lookup);
1336 rela++;
1337 }
1338 }
1339 }
Cache object: da2ba16e0006d0d7090ffc9f21ae877d
|