1 /*-
2 * Copyright (c) 1998 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 * $FreeBSD: src/sys/kern/link_elf.c,v 1.24 1999/12/24 15:33:36 bde Exp $
27 */
28
29 #include <sys/param.h>
30 #include <sys/kernel.h>
31 #include <sys/systm.h>
32 #include <sys/malloc.h>
33 #include <sys/proc.h>
34 #include <sys/nlookup.h>
35 #include <sys/fcntl.h>
36 #include <sys/vnode.h>
37 #include <sys/linker.h>
38 #include <machine/elf.h>
39
40 #include <vm/vm.h>
41 #include <vm/vm_param.h>
42 #include <vm/vm_zone.h>
43 #include <sys/lock.h>
44 #include <vm/pmap.h>
45 #include <vm/vm_map.h>
46
47 #if defined(__x86_64__) && defined(_KERNEL_VIRTUAL)
48 #include <stdio.h>
49 #endif
50
51 static int link_elf_preload_file(const char *, linker_file_t *);
52 static int link_elf_preload_finish(linker_file_t);
53 static int link_elf_load_file(const char*, linker_file_t*);
54 static int link_elf_lookup_symbol(linker_file_t, const char*,
55 c_linker_sym_t*);
56 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
57 static int link_elf_search_symbol(linker_file_t, caddr_t value,
58 c_linker_sym_t* sym, long* diffp);
59
60 static void link_elf_unload_file(linker_file_t);
61 static void link_elf_unload_module(linker_file_t);
62 static int link_elf_lookup_set(linker_file_t, const char *,
63 void ***, void ***, int *);
64 static int elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *);
65 static void link_elf_reloc_local(linker_file_t lf);
66
67 static struct linker_class_ops link_elf_class_ops = {
68 link_elf_load_file,
69 link_elf_preload_file,
70 };
71
72 static struct linker_file_ops link_elf_file_ops = {
73 .lookup_symbol = link_elf_lookup_symbol,
74 .symbol_values = link_elf_symbol_values,
75 .search_symbol = link_elf_search_symbol,
76 .unload = link_elf_unload_file,
77 .lookup_set = link_elf_lookup_set
78 };
79
80 static struct linker_file_ops link_elf_module_ops = {
81 .lookup_symbol = link_elf_lookup_symbol,
82 .symbol_values = link_elf_symbol_values,
83 .search_symbol = link_elf_search_symbol,
84 .preload_finish = link_elf_preload_finish,
85 .unload = link_elf_unload_module,
86 .lookup_set = link_elf_lookup_set,
87 };
88
89 typedef struct elf_file {
90 caddr_t address; /* Relocation address */
91 const Elf_Dyn* dynamic; /* Symbol table etc. */
92 Elf_Hashelt nbuckets; /* DT_HASH info */
93 Elf_Hashelt nchains;
94 const Elf_Hashelt* buckets;
95 const Elf_Hashelt* chains;
96 caddr_t hash;
97 caddr_t strtab; /* DT_STRTAB */
98 int strsz; /* DT_STRSZ */
99 const Elf_Sym* symtab; /* DT_SYMTAB */
100 Elf_Addr* got; /* DT_PLTGOT */
101 const Elf_Rel* pltrel; /* DT_JMPREL */
102 int pltrelsize; /* DT_PLTRELSZ */
103 const Elf_Rela* pltrela; /* DT_JMPREL */
104 int pltrelasize; /* DT_PLTRELSZ */
105 const Elf_Rel* rel; /* DT_REL */
106 int relsize; /* DT_RELSZ */
107 const Elf_Rela* rela; /* DT_RELA */
108 int relasize; /* DT_RELASZ */
109 caddr_t modptr;
110 const Elf_Sym* ddbsymtab; /* The symbol table we are using */
111 long ddbsymcnt; /* Number of symbols */
112 caddr_t ddbstrtab; /* String table */
113 long ddbstrcnt; /* number of bytes in string table */
114 caddr_t symbase; /* malloc'ed symbold base */
115 caddr_t strbase; /* malloc'ed string base */
116 } *elf_file_t;
117
118 static int parse_dynamic(linker_file_t lf);
119 static int relocate_file(linker_file_t lf);
120 static int parse_module_symbols(linker_file_t lf);
121
122 /*
123 * The kernel symbol table starts here.
124 */
125 extern struct _dynamic _DYNAMIC;
126
127 static void
link_elf_init(void * arg)128 link_elf_init(void* arg)
129 {
130 Elf_Dyn *dp;
131 caddr_t modptr, baseptr, sizeptr;
132 elf_file_t ef;
133 char *modname;
134
135 #if ELF_TARG_CLASS == ELFCLASS32
136 linker_add_class("elf32", NULL, &link_elf_class_ops);
137 #else
138 linker_add_class("elf64", NULL, &link_elf_class_ops);
139 #endif
140
141 dp = (Elf_Dyn*) &_DYNAMIC;
142 if (dp) {
143 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO);
144 ef->address = NULL;
145 ef->dynamic = dp;
146 modname = NULL;
147 modptr = preload_search_by_type("elf kernel");
148 if (modptr)
149 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
150 if (modname == NULL)
151 modname = "kernel";
152 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops);
153 if (linker_kernel_file == NULL)
154 panic("link_elf_init: Can't create linker structures for kernel");
155 parse_dynamic(linker_kernel_file);
156 #if defined(__x86_64__) && defined(_KERNEL_VIRTUAL)
157 fprintf(stderr, "WARNING: KERNBASE being used\n");
158 #endif
159 linker_kernel_file->address = (caddr_t) KERNBASE;
160 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
161
162 if (modptr) {
163 ef->modptr = modptr;
164 baseptr = preload_search_info(modptr, MODINFO_ADDR);
165 if (baseptr)
166 linker_kernel_file->address = *(caddr_t *)baseptr;
167 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
168 if (sizeptr)
169 linker_kernel_file->size = *(size_t *)sizeptr;
170 }
171 parse_module_symbols(linker_kernel_file);
172 linker_current_file = linker_kernel_file;
173 linker_kernel_file->flags |= LINKER_FILE_LINKED;
174 }
175 }
176
177 SYSINIT(link_elf, SI_BOOT2_KLD, SI_ORDER_SECOND, link_elf_init, 0);
178
179 static int
parse_module_symbols(linker_file_t lf)180 parse_module_symbols(linker_file_t lf)
181 {
182 elf_file_t ef = lf->priv;
183 caddr_t pointer;
184 caddr_t ssym, esym, base;
185 caddr_t strtab;
186 int strcnt;
187 Elf_Sym* symtab;
188 int symcnt;
189
190 if (ef->modptr == NULL)
191 return 0;
192 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
193 if (pointer == NULL)
194 return 0;
195 ssym = *(caddr_t *)pointer;
196 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
197 if (pointer == NULL)
198 return 0;
199 esym = *(caddr_t *)pointer;
200
201 base = ssym;
202
203 symcnt = *(long *)base;
204 base += sizeof(long);
205 symtab = (Elf_Sym *)base;
206 base += roundup(symcnt, sizeof(long));
207
208 if (base > esym || base < ssym) {
209 kprintf("Symbols are corrupt!\n");
210 return EINVAL;
211 }
212
213 strcnt = *(long *)base;
214 base += sizeof(long);
215 strtab = base;
216 base += roundup(strcnt, sizeof(long));
217
218 if (base > esym || base < ssym) {
219 kprintf("Symbols are corrupt!\n");
220 return EINVAL;
221 }
222
223 ef->ddbsymtab = symtab;
224 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
225 ef->ddbstrtab = strtab;
226 ef->ddbstrcnt = strcnt;
227
228 return 0;
229 }
230
231 static int
parse_dynamic(linker_file_t lf)232 parse_dynamic(linker_file_t lf)
233 {
234 elf_file_t ef = lf->priv;
235 const Elf_Dyn *dp;
236 int plttype = DT_REL;
237
238 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
239 switch (dp->d_tag) {
240 case DT_HASH:
241 {
242 /* From src/libexec/rtld-elf/rtld.c */
243 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
244 (ef->address + dp->d_un.d_ptr);
245 ef->nbuckets = hashtab[0];
246 ef->nchains = hashtab[1];
247 ef->buckets = hashtab + 2;
248 ef->chains = ef->buckets + ef->nbuckets;
249 break;
250 }
251 case DT_STRTAB:
252 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
253 break;
254 case DT_STRSZ:
255 ef->strsz = dp->d_un.d_val;
256 break;
257 case DT_SYMTAB:
258 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
259 break;
260 case DT_SYMENT:
261 if (dp->d_un.d_val != sizeof(Elf_Sym))
262 return ENOEXEC;
263 break;
264 case DT_PLTGOT:
265 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
266 break;
267 case DT_REL:
268 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
269 break;
270 case DT_RELSZ:
271 ef->relsize = dp->d_un.d_val;
272 break;
273 case DT_RELENT:
274 if (dp->d_un.d_val != sizeof(Elf_Rel))
275 return ENOEXEC;
276 break;
277 case DT_JMPREL:
278 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
279 break;
280 case DT_PLTRELSZ:
281 ef->pltrelsize = dp->d_un.d_val;
282 break;
283 case DT_RELA:
284 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
285 break;
286 case DT_RELASZ:
287 ef->relasize = dp->d_un.d_val;
288 break;
289 case DT_RELAENT:
290 if (dp->d_un.d_val != sizeof(Elf_Rela))
291 return ENOEXEC;
292 break;
293 case DT_PLTREL:
294 plttype = dp->d_un.d_val;
295 if (plttype != DT_REL && plttype != DT_RELA)
296 return ENOEXEC;
297 break;
298 }
299 }
300
301 if (plttype == DT_RELA) {
302 ef->pltrela = (const Elf_Rela *) ef->pltrel;
303 ef->pltrel = NULL;
304 ef->pltrelasize = ef->pltrelsize;
305 ef->pltrelsize = 0;
306 }
307
308 ef->ddbsymtab = ef->symtab;
309 ef->ddbsymcnt = ef->nchains;
310 ef->ddbstrtab = ef->strtab;
311 ef->ddbstrcnt = ef->strsz;
312
313 return 0;
314 }
315
316 static void
link_elf_error(const char * s)317 link_elf_error(const char *s)
318 {
319 kprintf("kldload: %s\n", s);
320 }
321
322 static int
link_elf_preload_file(const char * filename,linker_file_t * result)323 link_elf_preload_file(const char *filename, linker_file_t *result)
324 {
325 caddr_t modptr, baseptr, sizeptr, dynptr;
326 char *type;
327 elf_file_t ef;
328 linker_file_t lf;
329 int error;
330 vm_offset_t dp;
331
332 /*
333 * Look to see if we have the module preloaded.
334 */
335 modptr = preload_search_by_name(filename);
336 if (modptr == NULL)
337 return ENOENT;
338
339 /* It's preloaded, check we can handle it and collect information */
340 type = (char *)preload_search_info(modptr, MODINFO_TYPE);
341 baseptr = preload_search_info(modptr, MODINFO_ADDR);
342 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
343 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
344 if (type == NULL ||
345 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
346 strcmp(type, "elf module") != 0))
347 return (EFTYPE);
348 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
349 return (EINVAL);
350
351 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
352 ef->modptr = modptr;
353 ef->address = *(caddr_t *)baseptr;
354 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
355 ef->dynamic = (Elf_Dyn *)dp;
356 lf = linker_make_file(filename, ef, &link_elf_module_ops);
357 if (lf == NULL) {
358 kfree(ef, M_LINKER);
359 return ENOMEM;
360 }
361 lf->address = ef->address;
362 lf->size = *(size_t *)sizeptr;
363
364 error = parse_dynamic(lf);
365 if (error) {
366 linker_file_unload(lf);
367 return error;
368 }
369 link_elf_reloc_local(lf);
370 *result = lf;
371 return (0);
372 }
373
374 static int
link_elf_preload_finish(linker_file_t lf)375 link_elf_preload_finish(linker_file_t lf)
376 {
377 int error;
378
379 error = relocate_file(lf);
380 if (error)
381 return error;
382 parse_module_symbols(lf);
383
384 return (0);
385 }
386
387 static int
link_elf_load_file(const char * filename,linker_file_t * result)388 link_elf_load_file(const char* filename, linker_file_t* result)
389 {
390 struct nlookupdata nd;
391 struct thread *td = curthread; /* XXX */
392 struct proc *p = td->td_proc;
393 struct vnode *vp;
394 Elf_Ehdr *hdr;
395 caddr_t firstpage;
396 int nbytes, i;
397 Elf_Phdr *phdr;
398 Elf_Phdr *phlimit;
399 Elf_Phdr *segs[2];
400 int nsegs;
401 Elf_Phdr *phdyn;
402 caddr_t mapbase;
403 size_t mapsize;
404 Elf_Addr base_vaddr;
405 Elf_Addr base_vlimit;
406 int error = 0;
407 int resid;
408 elf_file_t ef;
409 linker_file_t lf;
410 char *pathname;
411 Elf_Shdr *shdr;
412 int symtabindex;
413 int symstrindex;
414 int symcnt;
415 int strcnt;
416
417 /* XXX Hack for firmware loading where p == NULL */
418 if (p == NULL) {
419 p = &proc0;
420 }
421
422 KKASSERT(p != NULL);
423 if (p->p_ucred == NULL) {
424 kprintf("link_elf_load_file: cannot load '%s' from filesystem"
425 " this early\n", filename);
426 return ENOENT;
427 }
428 shdr = NULL;
429 lf = NULL;
430 pathname = linker_search_path(filename);
431 if (pathname == NULL)
432 return ENOENT;
433
434 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP);
435 if (error == 0)
436 error = vn_open(&nd, NULL, FREAD, 0);
437 kfree(pathname, M_LINKER);
438 if (error) {
439 nlookup_done(&nd);
440 return error;
441 }
442 vp = nd.nl_open_vp;
443 nd.nl_open_vp = NULL;
444 nlookup_done(&nd);
445
446 /*
447 * Read the elf header from the file.
448 */
449 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK);
450 hdr = (Elf_Ehdr *)firstpage;
451 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0,
452 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
453 nbytes = PAGE_SIZE - resid;
454 if (error)
455 goto out;
456
457 if (!IS_ELF(*hdr)) {
458 error = ENOEXEC;
459 goto out;
460 }
461
462 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
463 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
464 link_elf_error("Unsupported file layout");
465 error = ENOEXEC;
466 goto out;
467 }
468 if (hdr->e_ident[EI_VERSION] != EV_CURRENT
469 || hdr->e_version != EV_CURRENT) {
470 link_elf_error("Unsupported file version");
471 error = ENOEXEC;
472 goto out;
473 }
474 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
475 error = ENOSYS;
476 goto out;
477 }
478 if (hdr->e_machine != ELF_TARG_MACH) {
479 link_elf_error("Unsupported machine");
480 error = ENOEXEC;
481 goto out;
482 }
483
484 /*
485 * We rely on the program header being in the first page. This is
486 * not strictly required by the ABI specification, but it seems to
487 * always true in practice. And, it simplifies things considerably.
488 */
489 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
490 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
491 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
492 link_elf_error("Unreadable program headers");
493
494 /*
495 * Scan the program header entries, and save key information.
496 *
497 * We rely on there being exactly two load segments, text and data,
498 * in that order.
499 */
500 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
501 phlimit = phdr + hdr->e_phnum;
502 nsegs = 0;
503 phdyn = NULL;
504 while (phdr < phlimit) {
505 switch (phdr->p_type) {
506
507 case PT_LOAD:
508 if (nsegs == 2) {
509 link_elf_error("Too many sections");
510 error = ENOEXEC;
511 goto out;
512 }
513 segs[nsegs] = phdr;
514 ++nsegs;
515 break;
516
517 case PT_PHDR:
518 break;
519
520 case PT_DYNAMIC:
521 phdyn = phdr;
522 break;
523
524 case PT_INTERP:
525 error = ENOSYS;
526 goto out;
527 }
528
529 ++phdr;
530 }
531 if (phdyn == NULL) {
532 link_elf_error("Object is not dynamically-linked");
533 error = ENOEXEC;
534 goto out;
535 }
536
537 /*
538 * Allocate the entire address space of the object, to stake out our
539 * contiguous region, and to establish the base address for relocation.
540 */
541 base_vaddr = trunc_page(segs[0]->p_vaddr);
542 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
543 mapsize = base_vlimit - base_vaddr;
544
545 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO);
546 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK);
547 mapbase = ef->address;
548
549 /*
550 * Read the text and data sections and zero the bss.
551 */
552 for (i = 0; i < 2; i++) {
553 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
554 error = vn_rdwr(UIO_READ, vp,
555 segbase, segs[i]->p_filesz, segs[i]->p_offset,
556 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
557 if (error) {
558 kfree(ef->address, M_LINKER);
559 kfree(ef, M_LINKER);
560 goto out;
561 }
562 bzero(segbase + segs[i]->p_filesz,
563 segs[i]->p_memsz - segs[i]->p_filesz);
564 }
565
566 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
567
568 lf = linker_make_file(filename, ef, &link_elf_file_ops);
569 if (lf == NULL) {
570 kfree(ef->address, M_LINKER);
571 kfree(ef, M_LINKER);
572 error = ENOMEM;
573 goto out;
574 }
575 lf->address = ef->address;
576 lf->size = mapsize;
577
578 error = parse_dynamic(lf);
579 if (error)
580 goto out;
581 link_elf_reloc_local(lf);
582 error = linker_load_dependencies(lf);
583 if (error)
584 goto out;
585 error = relocate_file(lf);
586 if (error)
587 goto out;
588
589 /* Try and load the symbol table if it's present. (you can strip it!) */
590 nbytes = hdr->e_shnum * hdr->e_shentsize;
591 if (nbytes == 0 || hdr->e_shoff == 0)
592 goto nosyms;
593 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
594 error = vn_rdwr(UIO_READ, vp,
595 (caddr_t)shdr, nbytes, hdr->e_shoff,
596 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
597 if (error)
598 goto out;
599 symtabindex = -1;
600 symstrindex = -1;
601 for (i = 0; i < hdr->e_shnum; i++) {
602 if (shdr[i].sh_type == SHT_SYMTAB) {
603 symtabindex = i;
604 symstrindex = shdr[i].sh_link;
605 }
606 }
607 if (symtabindex < 0 || symstrindex < 0)
608 goto nosyms;
609
610 symcnt = shdr[symtabindex].sh_size;
611 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK);
612 strcnt = shdr[symstrindex].sh_size;
613 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK);
614 error = vn_rdwr(UIO_READ, vp,
615 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
616 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
617 if (error)
618 goto out;
619 error = vn_rdwr(UIO_READ, vp,
620 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
621 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid);
622 if (error)
623 goto out;
624
625 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
626 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
627 ef->ddbstrcnt = strcnt;
628 ef->ddbstrtab = ef->strbase;
629
630 nosyms:
631
632 *result = lf;
633
634 out:
635 if (error && lf)
636 linker_file_unload(lf);
637 if (shdr)
638 kfree(shdr, M_LINKER);
639 if (firstpage)
640 kfree(firstpage, M_LINKER);
641 vn_unlock(vp);
642 vn_close(vp, FREAD, NULL);
643
644 return error;
645 }
646
647 Elf_Addr
elf_relocaddr(linker_file_t lf,Elf_Addr x)648 elf_relocaddr(linker_file_t lf, Elf_Addr x)
649 {
650 #if 0
651 elf_file_t ef;
652
653 ef = lf->priv;
654 if (x >= ef->pcpu_start && x < ef->pcpu_stop)
655 return ((x - ef->pcpu_start) + ef->pcpu_base);
656 #ifdef VIMAGE
657 if (x >= ef->vnet_start && x < ef->vnet_stop)
658 return ((x - ef->vnet_start) + ef->vnet_base);
659 #endif
660 #endif
661 return (x);
662 }
663
664 static void
link_elf_unload_file(linker_file_t file)665 link_elf_unload_file(linker_file_t file)
666 {
667 elf_file_t ef = file->priv;
668
669 if (ef) {
670 if (ef->address)
671 kfree(ef->address, M_LINKER);
672 if (ef->symbase)
673 kfree(ef->symbase, M_LINKER);
674 if (ef->strbase)
675 kfree(ef->strbase, M_LINKER);
676 kfree(ef, M_LINKER);
677 }
678 }
679
680 static void
link_elf_unload_module(linker_file_t file)681 link_elf_unload_module(linker_file_t file)
682 {
683 elf_file_t ef = file->priv;
684
685 if (ef)
686 kfree(ef, M_LINKER);
687 if (file->pathname)
688 preload_delete_name(file->pathname);
689 }
690
691 static const char *
symbol_name(elf_file_t ef,Elf_Size r_info)692 symbol_name(elf_file_t ef, Elf_Size r_info)
693 {
694 const Elf_Sym *ref;
695
696 if (ELF_R_SYM(r_info)) {
697 ref = ef->symtab + ELF_R_SYM(r_info);
698 return ef->strtab + ref->st_name;
699 } else
700 return NULL;
701 }
702
703 static int
relocate_file(linker_file_t lf)704 relocate_file(linker_file_t lf)
705 {
706 elf_file_t ef = lf->priv;
707 const Elf_Rel *rellim;
708 const Elf_Rel *rel;
709 const Elf_Rela *relalim;
710 const Elf_Rela *rela;
711 const char *symname;
712
713 /* Perform relocations without addend if there are any: */
714 rel = ef->rel;
715 if (rel) {
716 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
717 while (rel < rellim) {
718 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) {
719 symname = symbol_name(ef, rel->r_info);
720 kprintf("link_elf: symbol %s undefined\n", symname);
721 return ENOENT;
722 }
723 rel++;
724 }
725 }
726
727 /* Perform relocations with addend if there are any: */
728 rela = ef->rela;
729 if (rela) {
730 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
731 while (rela < relalim) {
732 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) {
733 symname = symbol_name(ef, rela->r_info);
734 kprintf("link_elf: symbol %s undefined\n", symname);
735 return ENOENT;
736 }
737 rela++;
738 }
739 }
740
741 /* Perform PLT relocations without addend if there are any: */
742 rel = ef->pltrel;
743 if (rel) {
744 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
745 while (rel < rellim) {
746 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) {
747 symname = symbol_name(ef, rel->r_info);
748 kprintf("link_elf: symbol %s undefined\n", symname);
749 return ENOENT;
750 }
751 rel++;
752 }
753 }
754
755 /* Perform relocations with addend if there are any: */
756 rela = ef->pltrela;
757 if (rela) {
758 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
759 while (rela < relalim) {
760 symname = symbol_name(ef, rela->r_info);
761 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) {
762 kprintf("link_elf: symbol %s undefined\n", symname);
763 return ENOENT;
764 }
765 rela++;
766 }
767 }
768
769 return 0;
770 }
771
772 /*
773 * Hash function for symbol table lookup. Don't even think about changing
774 * this. It is specified by the System V ABI.
775 */
776 static unsigned long
elf_hash(const char * name)777 elf_hash(const char *name)
778 {
779 const unsigned char *p = (const unsigned char *) name;
780 unsigned long h = 0;
781 unsigned long g;
782
783 while (*p != '\0') {
784 h = (h << 4) + *p++;
785 if ((g = h & 0xf0000000) != 0)
786 h ^= g >> 24;
787 h &= ~g;
788 }
789 return h;
790 }
791
792 static int
link_elf_lookup_symbol(linker_file_t lf,const char * name,c_linker_sym_t * sym)793 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
794 {
795 elf_file_t ef = lf->priv;
796 unsigned long symnum;
797 const Elf_Sym* symp;
798 const char *strp;
799 unsigned long hash;
800 int i;
801
802 /* If we don't have a hash, bail. */
803 if (ef->buckets == NULL || ef->nbuckets == 0) {
804 kprintf("link_elf_lookup_symbol: missing symbol hash table\n");
805 return ENOENT;
806 }
807
808 /* First, search hashed global symbols */
809 hash = elf_hash(name);
810 symnum = ef->buckets[hash % ef->nbuckets];
811
812 while (symnum != STN_UNDEF) {
813 if (symnum >= ef->nchains) {
814 kprintf("link_elf_lookup_symbol: corrupt symbol table\n");
815 return ENOENT;
816 }
817
818 symp = ef->symtab + symnum;
819 if (symp->st_name == 0) {
820 kprintf("link_elf_lookup_symbol: corrupt symbol table\n");
821 return ENOENT;
822 }
823
824 strp = ef->strtab + symp->st_name;
825
826 if (strcmp(name, strp) == 0) {
827 if (symp->st_shndx != SHN_UNDEF ||
828 (symp->st_value != 0 &&
829 ELF_ST_TYPE(symp->st_info) == STT_FUNC)
830 ) {
831 *sym = (c_linker_sym_t) symp;
832 return 0;
833 } else {
834 return ENOENT;
835 }
836 }
837
838 symnum = ef->chains[symnum];
839 }
840
841 /* If we have not found it, look at the full table (if loaded) */
842 if (ef->symtab == ef->ddbsymtab)
843 return ENOENT;
844
845 /* Exhaustive search */
846 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
847 strp = ef->ddbstrtab + symp->st_name;
848 if (strcmp(name, strp) == 0) {
849 if (symp->st_shndx != SHN_UNDEF ||
850 (symp->st_value != 0 &&
851 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
852 *sym = (c_linker_sym_t) symp;
853 return 0;
854 } else {
855 return ENOENT;
856 }
857 }
858 }
859 return ENOENT;
860 }
861
862 static int
link_elf_symbol_values(linker_file_t lf,c_linker_sym_t sym,linker_symval_t * symval)863 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval)
864 {
865 elf_file_t ef = lf->priv;
866 const Elf_Sym *es = (const Elf_Sym *)sym;
867
868 symval->value = 0; /* avoid gcc warnings */
869
870 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
871 symval->name = ef->strtab + es->st_name;
872 symval->value = ef->address + es->st_value;
873 symval->size = es->st_size;
874 return 0;
875 }
876 if (ef->symtab == ef->ddbsymtab)
877 return ENOENT;
878 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
879 symval->name = ef->ddbstrtab + es->st_name;
880 symval->value = ef->address + es->st_value;
881 symval->size = es->st_size;
882 return 0;
883 }
884 return ENOENT;
885 }
886
887 static int
link_elf_search_symbol(linker_file_t lf,caddr_t value,c_linker_sym_t * sym,long * diffp)888 link_elf_search_symbol(linker_file_t lf, caddr_t value,
889 c_linker_sym_t *sym, long *diffp)
890 {
891 elf_file_t ef = lf->priv;
892 u_long off = (uintptr_t)(void *)value;
893 u_long diff = off;
894 u_long st_value;
895 const Elf_Sym *es;
896 const Elf_Sym *best = NULL;
897 int i;
898
899 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
900 if (es->st_name == 0)
901 continue;
902 st_value = es->st_value + (uintptr_t)(void *)ef->address;
903 if (off >= st_value) {
904 if (off - st_value < diff) {
905 diff = off - st_value;
906 best = es;
907 if (diff == 0)
908 break;
909 } else if (off - st_value == diff) {
910 best = es;
911 }
912 }
913 }
914 if (best == NULL)
915 *diffp = off;
916 else
917 *diffp = diff;
918 *sym = (c_linker_sym_t) best;
919
920 return 0;
921 }
922
923 /*
924 * Look up a linker set on an ELF system.
925 */
926 static int
link_elf_lookup_set(linker_file_t lf,const char * name,void *** startp,void *** stopp,int * countp)927 link_elf_lookup_set(linker_file_t lf, const char *name,
928 void ***startp, void ***stopp, int *countp)
929 {
930 c_linker_sym_t sym;
931 linker_symval_t symval;
932 char *setsym;
933 void **start, **stop;
934 int len, error = 0, count;
935
936 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
937 setsym = kmalloc(len, M_LINKER, M_WAITOK);
938
939 /* get address of first entry */
940 ksnprintf(setsym, len, "%s%s", "__start_set_", name);
941 error = link_elf_lookup_symbol(lf, setsym, &sym);
942 if (error)
943 goto out;
944 link_elf_symbol_values(lf, sym, &symval);
945 if (symval.value == NULL) {
946 error = ESRCH;
947 goto out;
948 }
949 start = (void **)symval.value;
950
951 /* get address of last entry */
952 ksnprintf(setsym, len, "%s%s", "__stop_set_", name);
953 error = link_elf_lookup_symbol(lf, setsym, &sym);
954 if (error)
955 goto out;
956 link_elf_symbol_values(lf, sym, &symval);
957 if (symval.value == NULL) {
958 error = ESRCH;
959 goto out;
960 }
961 stop = (void **)symval.value;
962
963 /* and the number of entries */
964 count = stop - start;
965
966 /* and copy out */
967 if (startp)
968 *startp = start;
969 if (stopp)
970 *stopp = stop;
971 if (countp)
972 *countp = count;
973
974 out:
975 kfree(setsym, M_LINKER);
976 return error;
977 }
978
979 /*
980 * Symbol lookup function that can be used when the symbol index is known (ie
981 * in relocations). It uses the symbol index instead of doing a fully fledged
982 * hash table based lookup when such is valid. For example for local symbols.
983 * This is not only more efficient, it's also more correct. It's not always
984 * the case that the symbol can be found through the hash table.
985 */
986 static int
elf_lookup(linker_file_t lf,Elf_Size symidx,int deps,Elf_Addr * result)987 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result)
988 {
989 elf_file_t ef = lf->priv;
990 const Elf_Sym *sym;
991 const char *symbol;
992
993 /* Don't even try to lookup the symbol if the index is bogus. */
994 if (symidx >= ef->nchains)
995 return (ENOENT);
996
997 sym = ef->symtab + symidx;
998
999 /*
1000 * Don't do a full lookup when the symbol is local. It may even
1001 * fail because it may not be found through the hash table.
1002 */
1003 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1004 /* Force lookup failure when we have an insanity. */
1005 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1006 return (ENOENT);
1007 return ((Elf_Addr) ef->address + sym->st_value);
1008 }
1009 /*
1010 * XXX we can avoid doing a hash table based lookup for global
1011 * symbols as well. This however is not always valid, so we'll
1012 * just do it the hard way for now. Performance tweaks can
1013 * always be added.
1014 */
1015
1016 symbol = ef->strtab + sym->st_name;
1017
1018 /* Force a lookup failure if the symbol name is bogus. */
1019 if (*symbol == 0)
1020 return (ENOENT);
1021
1022 return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result));
1023 }
1024 static void
link_elf_reloc_local(linker_file_t lf)1025 link_elf_reloc_local(linker_file_t lf)
1026 {
1027 elf_file_t ef = lf->priv;
1028 const Elf_Rel *rellim;
1029 const Elf_Rel *rel;
1030 const Elf_Rela *relalim;
1031 const Elf_Rela *rela;
1032
1033 /* Perform relocations without addend if there are any: */
1034 if ((rel = ef->rel) != NULL) {
1035 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1036 while (rel < rellim) {
1037 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
1038 elf_lookup);
1039 rel++;
1040 }
1041 }
1042
1043 /* Perform relocations with addend if there are any: */
1044 if ((rela = ef->rela) != NULL) {
1045 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
1046 while (rela < relalim) {
1047 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
1048 elf_lookup);
1049 rela++;
1050 }
1051 }
1052 }
1053