xref: /freebsd/sys/kern/link_elf_obj.c (revision ff0ba87247820afbdfdc1b307c803f7923d0e4d3)
1 /*-
2  * Copyright (c) 1998-2000 Doug Rabson
3  * Copyright (c) 2004 Peter Wemm
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 #include "opt_ddb.h"
32 
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/kernel.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mutex.h>
39 #include <sys/mount.h>
40 #include <sys/proc.h>
41 #include <sys/namei.h>
42 #include <sys/fcntl.h>
43 #include <sys/vnode.h>
44 #include <sys/linker.h>
45 
46 #include <machine/elf.h>
47 
48 #include <net/vnet.h>
49 
50 #include <security/mac/mac_framework.h>
51 
52 #include <vm/vm.h>
53 #include <vm/vm_param.h>
54 #include <vm/vm_object.h>
55 #include <vm/vm_kern.h>
56 #include <vm/vm_extern.h>
57 #include <vm/pmap.h>
58 #include <vm/vm_map.h>
59 
60 #include <sys/link_elf.h>
61 
62 #ifdef DDB_CTF
63 #include <net/zlib.h>
64 #endif
65 
66 #include "linker_if.h"
67 
68 typedef struct {
69 	void		*addr;
70 	Elf_Off		size;
71 	int		flags;
72 	int		sec;	/* Original section */
73 	char		*name;
74 } Elf_progent;
75 
76 typedef struct {
77 	Elf_Rel		*rel;
78 	int		nrel;
79 	int		sec;
80 } Elf_relent;
81 
82 typedef struct {
83 	Elf_Rela	*rela;
84 	int		nrela;
85 	int		sec;
86 } Elf_relaent;
87 
88 
89 typedef struct elf_file {
90 	struct linker_file lf;		/* Common fields */
91 
92 	int		preloaded;
93 	caddr_t		address;	/* Relocation address */
94 	vm_object_t	object;		/* VM object to hold file pages */
95 	Elf_Shdr	*e_shdr;
96 
97 	Elf_progent	*progtab;
98 	int		nprogtab;
99 
100 	Elf_relaent	*relatab;
101 	int		nrelatab;
102 
103 	Elf_relent	*reltab;
104 	int		nreltab;
105 
106 	Elf_Sym		*ddbsymtab;	/* The symbol table we are using */
107 	long		ddbsymcnt;	/* Number of symbols */
108 	caddr_t		ddbstrtab;	/* String table */
109 	long		ddbstrcnt;	/* number of bytes in string table */
110 
111 	caddr_t		shstrtab;	/* Section name string table */
112 	long		shstrcnt;	/* number of bytes in string table */
113 
114 	caddr_t		ctftab;		/* CTF table */
115 	long		ctfcnt;		/* number of bytes in CTF table */
116 	caddr_t		ctfoff;		/* CTF offset table */
117 	caddr_t		typoff;		/* Type offset table */
118 	long		typlen;		/* Number of type entries. */
119 
120 } *elf_file_t;
121 
122 #include <kern/kern_ctf.c>
123 
124 static int	link_elf_link_preload(linker_class_t cls,
125 		    const char *, linker_file_t *);
126 static int	link_elf_link_preload_finish(linker_file_t);
127 static int	link_elf_load_file(linker_class_t, const char *, linker_file_t *);
128 static int	link_elf_lookup_symbol(linker_file_t, const char *,
129 		    c_linker_sym_t *);
130 static int	link_elf_symbol_values(linker_file_t, c_linker_sym_t,
131 		    linker_symval_t *);
132 static int	link_elf_search_symbol(linker_file_t, caddr_t value,
133 		    c_linker_sym_t *sym, long *diffp);
134 
135 static void	link_elf_unload_file(linker_file_t);
136 static int	link_elf_lookup_set(linker_file_t, const char *,
137 		    void ***, void ***, int *);
138 static int	link_elf_each_function_name(linker_file_t,
139 		    int (*)(const char *, void *), void *);
140 static int	link_elf_each_function_nameval(linker_file_t,
141 				linker_function_nameval_callback_t,
142 				void *);
143 static void	link_elf_reloc_local(linker_file_t);
144 static long	link_elf_symtab_get(linker_file_t, const Elf_Sym **);
145 static long	link_elf_strtab_get(linker_file_t, caddr_t *);
146 
147 static Elf_Addr elf_obj_lookup(linker_file_t lf, Elf_Size symidx, int deps);
148 
149 static kobj_method_t link_elf_methods[] = {
150 	KOBJMETHOD(linker_lookup_symbol,	link_elf_lookup_symbol),
151 	KOBJMETHOD(linker_symbol_values,	link_elf_symbol_values),
152 	KOBJMETHOD(linker_search_symbol,	link_elf_search_symbol),
153 	KOBJMETHOD(linker_unload,		link_elf_unload_file),
154 	KOBJMETHOD(linker_load_file,		link_elf_load_file),
155 	KOBJMETHOD(linker_link_preload,		link_elf_link_preload),
156 	KOBJMETHOD(linker_link_preload_finish,	link_elf_link_preload_finish),
157 	KOBJMETHOD(linker_lookup_set,		link_elf_lookup_set),
158 	KOBJMETHOD(linker_each_function_name,	link_elf_each_function_name),
159 	KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
160 	KOBJMETHOD(linker_ctf_get,		link_elf_ctf_get),
161 	KOBJMETHOD(linker_symtab_get, 		link_elf_symtab_get),
162 	KOBJMETHOD(linker_strtab_get, 		link_elf_strtab_get),
163 	{ 0, 0 }
164 };
165 
166 static struct linker_class link_elf_class = {
167 #if ELF_TARG_CLASS == ELFCLASS32
168 	"elf32_obj",
169 #else
170 	"elf64_obj",
171 #endif
172 	link_elf_methods, sizeof(struct elf_file)
173 };
174 
175 static int	relocate_file(elf_file_t ef);
176 
177 static void
178 link_elf_error(const char *filename, const char *s)
179 {
180 	if (filename == NULL)
181 		printf("kldload: %s\n", s);
182 	else
183 		printf("kldload: %s: %s\n", filename, s);
184 }
185 
186 static void
187 link_elf_init(void *arg)
188 {
189 
190 	linker_add_class(&link_elf_class);
191 }
192 
193 SYSINIT(link_elf_obj, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
194 
195 static int
196 link_elf_link_preload(linker_class_t cls, const char *filename,
197     linker_file_t *result)
198 {
199 	Elf_Ehdr *hdr;
200 	Elf_Shdr *shdr;
201 	Elf_Sym *es;
202 	void *modptr, *baseptr, *sizeptr;
203 	char *type;
204 	elf_file_t ef;
205 	linker_file_t lf;
206 	Elf_Addr off;
207 	int error, i, j, pb, ra, rl, shstrindex, symstrindex, symtabindex;
208 
209 	/* Look to see if we have the file preloaded */
210 	modptr = preload_search_by_name(filename);
211 	if (modptr == NULL)
212 		return ENOENT;
213 
214 	type = (char *)preload_search_info(modptr, MODINFO_TYPE);
215 	baseptr = preload_search_info(modptr, MODINFO_ADDR);
216 	sizeptr = preload_search_info(modptr, MODINFO_SIZE);
217 	hdr = (Elf_Ehdr *)preload_search_info(modptr, MODINFO_METADATA |
218 	    MODINFOMD_ELFHDR);
219 	shdr = (Elf_Shdr *)preload_search_info(modptr, MODINFO_METADATA |
220 	    MODINFOMD_SHDR);
221 	if (type == NULL || (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE)
222 	    " obj module") != 0 &&
223 	    strcmp(type, "elf obj module") != 0)) {
224 		return (EFTYPE);
225 	}
226 	if (baseptr == NULL || sizeptr == NULL || hdr == NULL ||
227 	    shdr == NULL)
228 		return (EINVAL);
229 
230 	lf = linker_make_file(filename, &link_elf_class);
231 	if (lf == NULL)
232 		return (ENOMEM);
233 
234 	ef = (elf_file_t)lf;
235 	ef->preloaded = 1;
236 	ef->address = *(caddr_t *)baseptr;
237 	lf->address = *(caddr_t *)baseptr;
238 	lf->size = *(size_t *)sizeptr;
239 
240 	if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
241 	    hdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
242 	    hdr->e_ident[EI_VERSION] != EV_CURRENT ||
243 	    hdr->e_version != EV_CURRENT ||
244 	    hdr->e_type != ET_REL ||
245 	    hdr->e_machine != ELF_TARG_MACH) {
246 		error = EFTYPE;
247 		goto out;
248 	}
249 	ef->e_shdr = shdr;
250 
251 	/* Scan the section header for information and table sizing. */
252 	symtabindex = -1;
253 	symstrindex = -1;
254 	for (i = 0; i < hdr->e_shnum; i++) {
255 		switch (shdr[i].sh_type) {
256 		case SHT_PROGBITS:
257 		case SHT_NOBITS:
258 			ef->nprogtab++;
259 			break;
260 		case SHT_SYMTAB:
261 			symtabindex = i;
262 			symstrindex = shdr[i].sh_link;
263 			break;
264 		case SHT_REL:
265 			ef->nreltab++;
266 			break;
267 		case SHT_RELA:
268 			ef->nrelatab++;
269 			break;
270 		}
271 	}
272 
273 	shstrindex = hdr->e_shstrndx;
274 	if (ef->nprogtab == 0 || symstrindex < 0 ||
275 	    symstrindex >= hdr->e_shnum ||
276 	    shdr[symstrindex].sh_type != SHT_STRTAB || shstrindex == 0 ||
277 	    shstrindex >= hdr->e_shnum ||
278 	    shdr[shstrindex].sh_type != SHT_STRTAB) {
279 		printf("%s: bad/missing section headers\n", filename);
280 		error = ENOEXEC;
281 		goto out;
282 	}
283 
284 	/* Allocate space for tracking the load chunks */
285 	if (ef->nprogtab != 0)
286 		ef->progtab = malloc(ef->nprogtab * sizeof(*ef->progtab),
287 		    M_LINKER, M_WAITOK | M_ZERO);
288 	if (ef->nreltab != 0)
289 		ef->reltab = malloc(ef->nreltab * sizeof(*ef->reltab),
290 		    M_LINKER, M_WAITOK | M_ZERO);
291 	if (ef->nrelatab != 0)
292 		ef->relatab = malloc(ef->nrelatab * sizeof(*ef->relatab),
293 		    M_LINKER, M_WAITOK | M_ZERO);
294 	if ((ef->nprogtab != 0 && ef->progtab == NULL) ||
295 	    (ef->nreltab != 0 && ef->reltab == NULL) ||
296 	    (ef->nrelatab != 0 && ef->relatab == NULL)) {
297 		error = ENOMEM;
298 		goto out;
299 	}
300 
301 	/* XXX, relocate the sh_addr fields saved by the loader. */
302 	off = 0;
303 	for (i = 0; i < hdr->e_shnum; i++) {
304 		if (shdr[i].sh_addr != 0 && (off == 0 || shdr[i].sh_addr < off))
305 			off = shdr[i].sh_addr;
306 	}
307 	for (i = 0; i < hdr->e_shnum; i++) {
308 		if (shdr[i].sh_addr != 0)
309 			shdr[i].sh_addr = shdr[i].sh_addr - off +
310 			    (Elf_Addr)ef->address;
311 	}
312 
313 	ef->ddbsymcnt = shdr[symtabindex].sh_size / sizeof(Elf_Sym);
314 	ef->ddbsymtab = (Elf_Sym *)shdr[symtabindex].sh_addr;
315 	ef->ddbstrcnt = shdr[symstrindex].sh_size;
316 	ef->ddbstrtab = (char *)shdr[symstrindex].sh_addr;
317 	ef->shstrcnt = shdr[shstrindex].sh_size;
318 	ef->shstrtab = (char *)shdr[shstrindex].sh_addr;
319 
320 	/* Now fill out progtab and the relocation tables. */
321 	pb = 0;
322 	rl = 0;
323 	ra = 0;
324 	for (i = 0; i < hdr->e_shnum; i++) {
325 		switch (shdr[i].sh_type) {
326 		case SHT_PROGBITS:
327 		case SHT_NOBITS:
328 			ef->progtab[pb].addr = (void *)shdr[i].sh_addr;
329 			if (shdr[i].sh_type == SHT_PROGBITS)
330 				ef->progtab[pb].name = "<<PROGBITS>>";
331 			else
332 				ef->progtab[pb].name = "<<NOBITS>>";
333 			ef->progtab[pb].size = shdr[i].sh_size;
334 			ef->progtab[pb].sec = i;
335 			if (ef->shstrtab && shdr[i].sh_name != 0)
336 				ef->progtab[pb].name =
337 				    ef->shstrtab + shdr[i].sh_name;
338 			if (ef->progtab[pb].name != NULL &&
339 			    !strcmp(ef->progtab[pb].name, DPCPU_SETNAME)) {
340 				void *dpcpu;
341 
342 				dpcpu = dpcpu_alloc(shdr[i].sh_size);
343 				if (dpcpu == NULL) {
344 					error = ENOSPC;
345 					goto out;
346 				}
347 				memcpy(dpcpu, ef->progtab[pb].addr,
348 				    ef->progtab[pb].size);
349 				dpcpu_copy(dpcpu, shdr[i].sh_size);
350 				ef->progtab[pb].addr = dpcpu;
351 #ifdef VIMAGE
352 			} else if (ef->progtab[pb].name != NULL &&
353 			    !strcmp(ef->progtab[pb].name, VNET_SETNAME)) {
354 				void *vnet_data;
355 
356 				vnet_data = vnet_data_alloc(shdr[i].sh_size);
357 				if (vnet_data == NULL) {
358 					error = ENOSPC;
359 					goto out;
360 				}
361 				memcpy(vnet_data, ef->progtab[pb].addr,
362 				    ef->progtab[pb].size);
363 				vnet_data_copy(vnet_data, shdr[i].sh_size);
364 				ef->progtab[pb].addr = vnet_data;
365 #endif
366 			} else if (ef->progtab[pb].name != NULL &&
367 			    !strcmp(ef->progtab[pb].name, ".ctors")) {
368 				lf->ctors_addr = ef->progtab[pb].addr;
369 				lf->ctors_size = shdr[i].sh_size;
370 			}
371 
372 			/* Update all symbol values with the offset. */
373 			for (j = 0; j < ef->ddbsymcnt; j++) {
374 				es = &ef->ddbsymtab[j];
375 				if (es->st_shndx != i)
376 					continue;
377 				es->st_value += (Elf_Addr)ef->progtab[pb].addr;
378 			}
379 			pb++;
380 			break;
381 		case SHT_REL:
382 			ef->reltab[rl].rel = (Elf_Rel *)shdr[i].sh_addr;
383 			ef->reltab[rl].nrel = shdr[i].sh_size / sizeof(Elf_Rel);
384 			ef->reltab[rl].sec = shdr[i].sh_info;
385 			rl++;
386 			break;
387 		case SHT_RELA:
388 			ef->relatab[ra].rela = (Elf_Rela *)shdr[i].sh_addr;
389 			ef->relatab[ra].nrela =
390 			    shdr[i].sh_size / sizeof(Elf_Rela);
391 			ef->relatab[ra].sec = shdr[i].sh_info;
392 			ra++;
393 			break;
394 		}
395 	}
396 	if (pb != ef->nprogtab)
397 		panic("lost progbits");
398 	if (rl != ef->nreltab)
399 		panic("lost reltab");
400 	if (ra != ef->nrelatab)
401 		panic("lost relatab");
402 
403 	/* Local intra-module relocations */
404 	link_elf_reloc_local(lf);
405 
406 	*result = lf;
407 	return (0);
408 
409 out:
410 	/* preload not done this way */
411 	linker_file_unload(lf, LINKER_UNLOAD_FORCE);
412 	return (error);
413 }
414 
415 static void
416 link_elf_invoke_ctors(caddr_t addr, size_t size)
417 {
418 	void (**ctor)(void);
419 	size_t i, cnt;
420 
421 	if (addr == NULL || size == 0)
422 		return;
423 	cnt = size / sizeof(*ctor);
424 	ctor = (void *)addr;
425 	for (i = 0; i < cnt; i++) {
426 		if (ctor[i] != NULL)
427 			(*ctor[i])();
428 	}
429 }
430 
431 static int
432 link_elf_link_preload_finish(linker_file_t lf)
433 {
434 	elf_file_t ef;
435 	int error;
436 
437 	ef = (elf_file_t)lf;
438 	error = relocate_file(ef);
439 	if (error)
440 		return error;
441 
442 	/* Notify MD code that a module is being loaded. */
443 	error = elf_cpu_load_file(lf);
444 	if (error)
445 		return (error);
446 
447 	/* Invoke .ctors */
448 	link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
449 	return (0);
450 }
451 
452 static int
453 link_elf_load_file(linker_class_t cls, const char *filename,
454     linker_file_t *result)
455 {
456 	struct nameidata nd;
457 	struct thread *td = curthread;	/* XXX */
458 	Elf_Ehdr *hdr;
459 	Elf_Shdr *shdr;
460 	Elf_Sym *es;
461 	int nbytes, i, j;
462 	vm_offset_t mapbase;
463 	size_t mapsize;
464 	int error = 0;
465 	ssize_t resid;
466 	int flags;
467 	elf_file_t ef;
468 	linker_file_t lf;
469 	int symtabindex;
470 	int symstrindex;
471 	int shstrindex;
472 	int nsym;
473 	int pb, rl, ra;
474 	int alignmask;
475 
476 	shdr = NULL;
477 	lf = NULL;
478 	mapsize = 0;
479 	hdr = NULL;
480 
481 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
482 	flags = FREAD;
483 	error = vn_open(&nd, &flags, 0, NULL);
484 	if (error)
485 		return error;
486 	NDFREE(&nd, NDF_ONLY_PNBUF);
487 	if (nd.ni_vp->v_type != VREG) {
488 		error = ENOEXEC;
489 		goto out;
490 	}
491 #ifdef MAC
492 	error = mac_kld_check_load(td->td_ucred, nd.ni_vp);
493 	if (error) {
494 		goto out;
495 	}
496 #endif
497 
498 	/* Read the elf header from the file. */
499 	hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK);
500 	error = vn_rdwr(UIO_READ, nd.ni_vp, (void *)hdr, sizeof(*hdr), 0,
501 	    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
502 	    &resid, td);
503 	if (error)
504 		goto out;
505 	if (resid != 0){
506 		error = ENOEXEC;
507 		goto out;
508 	}
509 
510 	if (!IS_ELF(*hdr)) {
511 		error = ENOEXEC;
512 		goto out;
513 	}
514 
515 	if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
516 	    || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
517 		link_elf_error(filename, "Unsupported file layout");
518 		error = ENOEXEC;
519 		goto out;
520 	}
521 	if (hdr->e_ident[EI_VERSION] != EV_CURRENT
522 	    || hdr->e_version != EV_CURRENT) {
523 		link_elf_error(filename, "Unsupported file version");
524 		error = ENOEXEC;
525 		goto out;
526 	}
527 	if (hdr->e_type != ET_REL) {
528 		error = ENOSYS;
529 		goto out;
530 	}
531 	if (hdr->e_machine != ELF_TARG_MACH) {
532 		link_elf_error(filename, "Unsupported machine");
533 		error = ENOEXEC;
534 		goto out;
535 	}
536 
537 	lf = linker_make_file(filename, &link_elf_class);
538 	if (!lf) {
539 		error = ENOMEM;
540 		goto out;
541 	}
542 	ef = (elf_file_t) lf;
543 	ef->nprogtab = 0;
544 	ef->e_shdr = 0;
545 	ef->nreltab = 0;
546 	ef->nrelatab = 0;
547 
548 	/* Allocate and read in the section header */
549 	nbytes = hdr->e_shnum * hdr->e_shentsize;
550 	if (nbytes == 0 || hdr->e_shoff == 0 ||
551 	    hdr->e_shentsize != sizeof(Elf_Shdr)) {
552 		error = ENOEXEC;
553 		goto out;
554 	}
555 	shdr = malloc(nbytes, M_LINKER, M_WAITOK);
556 	ef->e_shdr = shdr;
557 	error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes, hdr->e_shoff,
558 	    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid, td);
559 	if (error)
560 		goto out;
561 	if (resid) {
562 		error = ENOEXEC;
563 		goto out;
564 	}
565 
566 	/* Scan the section header for information and table sizing. */
567 	nsym = 0;
568 	symtabindex = -1;
569 	symstrindex = -1;
570 	for (i = 0; i < hdr->e_shnum; i++) {
571 		if (shdr[i].sh_size == 0)
572 			continue;
573 		switch (shdr[i].sh_type) {
574 		case SHT_PROGBITS:
575 		case SHT_NOBITS:
576 			ef->nprogtab++;
577 			break;
578 		case SHT_SYMTAB:
579 			nsym++;
580 			symtabindex = i;
581 			symstrindex = shdr[i].sh_link;
582 			break;
583 		case SHT_REL:
584 			ef->nreltab++;
585 			break;
586 		case SHT_RELA:
587 			ef->nrelatab++;
588 			break;
589 		case SHT_STRTAB:
590 			break;
591 		}
592 	}
593 	if (ef->nprogtab == 0) {
594 		link_elf_error(filename, "file has no contents");
595 		error = ENOEXEC;
596 		goto out;
597 	}
598 	if (nsym != 1) {
599 		/* Only allow one symbol table for now */
600 		link_elf_error(filename, "file has no valid symbol table");
601 		error = ENOEXEC;
602 		goto out;
603 	}
604 	if (symstrindex < 0 || symstrindex > hdr->e_shnum ||
605 	    shdr[symstrindex].sh_type != SHT_STRTAB) {
606 		link_elf_error(filename, "file has invalid symbol strings");
607 		error = ENOEXEC;
608 		goto out;
609 	}
610 
611 	/* Allocate space for tracking the load chunks */
612 	if (ef->nprogtab != 0)
613 		ef->progtab = malloc(ef->nprogtab * sizeof(*ef->progtab),
614 		    M_LINKER, M_WAITOK | M_ZERO);
615 	if (ef->nreltab != 0)
616 		ef->reltab = malloc(ef->nreltab * sizeof(*ef->reltab),
617 		    M_LINKER, M_WAITOK | M_ZERO);
618 	if (ef->nrelatab != 0)
619 		ef->relatab = malloc(ef->nrelatab * sizeof(*ef->relatab),
620 		    M_LINKER, M_WAITOK | M_ZERO);
621 
622 	if (symtabindex == -1)
623 		panic("lost symbol table index");
624 	/* Allocate space for and load the symbol table */
625 	ef->ddbsymcnt = shdr[symtabindex].sh_size / sizeof(Elf_Sym);
626 	ef->ddbsymtab = malloc(shdr[symtabindex].sh_size, M_LINKER, M_WAITOK);
627 	error = vn_rdwr(UIO_READ, nd.ni_vp, (void *)ef->ddbsymtab,
628 	    shdr[symtabindex].sh_size, shdr[symtabindex].sh_offset,
629 	    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
630 	    &resid, td);
631 	if (error)
632 		goto out;
633 	if (resid != 0){
634 		error = EINVAL;
635 		goto out;
636 	}
637 
638 	if (symstrindex == -1)
639 		panic("lost symbol string index");
640 	/* Allocate space for and load the symbol strings */
641 	ef->ddbstrcnt = shdr[symstrindex].sh_size;
642 	ef->ddbstrtab = malloc(shdr[symstrindex].sh_size, M_LINKER, M_WAITOK);
643 	error = vn_rdwr(UIO_READ, nd.ni_vp, ef->ddbstrtab,
644 	    shdr[symstrindex].sh_size, shdr[symstrindex].sh_offset,
645 	    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
646 	    &resid, td);
647 	if (error)
648 		goto out;
649 	if (resid != 0){
650 		error = EINVAL;
651 		goto out;
652 	}
653 
654 	/* Do we have a string table for the section names?  */
655 	shstrindex = -1;
656 	if (hdr->e_shstrndx != 0 &&
657 	    shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) {
658 		shstrindex = hdr->e_shstrndx;
659 		ef->shstrcnt = shdr[shstrindex].sh_size;
660 		ef->shstrtab = malloc(shdr[shstrindex].sh_size, M_LINKER,
661 		    M_WAITOK);
662 		error = vn_rdwr(UIO_READ, nd.ni_vp, ef->shstrtab,
663 		    shdr[shstrindex].sh_size, shdr[shstrindex].sh_offset,
664 		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
665 		    &resid, td);
666 		if (error)
667 			goto out;
668 		if (resid != 0){
669 			error = EINVAL;
670 			goto out;
671 		}
672 	}
673 
674 	/* Size up code/data(progbits) and bss(nobits). */
675 	alignmask = 0;
676 	for (i = 0; i < hdr->e_shnum; i++) {
677 		if (shdr[i].sh_size == 0)
678 			continue;
679 		switch (shdr[i].sh_type) {
680 		case SHT_PROGBITS:
681 		case SHT_NOBITS:
682 			alignmask = shdr[i].sh_addralign - 1;
683 			mapsize += alignmask;
684 			mapsize &= ~alignmask;
685 			mapsize += shdr[i].sh_size;
686 			break;
687 		}
688 	}
689 
690 	/*
691 	 * We know how much space we need for the text/data/bss/etc.
692 	 * This stuff needs to be in a single chunk so that profiling etc
693 	 * can get the bounds and gdb can associate offsets with modules
694 	 */
695 	ef->object = vm_object_allocate(OBJT_DEFAULT,
696 	    round_page(mapsize) >> PAGE_SHIFT);
697 	if (ef->object == NULL) {
698 		error = ENOMEM;
699 		goto out;
700 	}
701 	ef->address = (caddr_t) vm_map_min(kernel_map);
702 
703 	/*
704 	 * In order to satisfy amd64's architectural requirements on the
705 	 * location of code and data in the kernel's address space, request a
706 	 * mapping that is above the kernel.
707 	 */
708 #ifdef __amd64__
709 	mapbase = KERNBASE;
710 #else
711 	mapbase = VM_MIN_KERNEL_ADDRESS;
712 #endif
713 	error = vm_map_find(kernel_map, ef->object, 0, &mapbase,
714 	    round_page(mapsize), 0, VMFS_OPTIMAL_SPACE, VM_PROT_ALL,
715 	    VM_PROT_ALL, 0);
716 	if (error) {
717 		vm_object_deallocate(ef->object);
718 		ef->object = 0;
719 		goto out;
720 	}
721 
722 	/* Wire the pages */
723 	error = vm_map_wire(kernel_map, mapbase,
724 	    mapbase + round_page(mapsize),
725 	    VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
726 	if (error != KERN_SUCCESS) {
727 		error = ENOMEM;
728 		goto out;
729 	}
730 
731 	/* Inform the kld system about the situation */
732 	lf->address = ef->address = (caddr_t)mapbase;
733 	lf->size = mapsize;
734 
735 	/*
736 	 * Now load code/data(progbits), zero bss(nobits), allocate space for
737 	 * and load relocs
738 	 */
739 	pb = 0;
740 	rl = 0;
741 	ra = 0;
742 	alignmask = 0;
743 	for (i = 0; i < hdr->e_shnum; i++) {
744 		if (shdr[i].sh_size == 0)
745 			continue;
746 		switch (shdr[i].sh_type) {
747 		case SHT_PROGBITS:
748 		case SHT_NOBITS:
749 			alignmask = shdr[i].sh_addralign - 1;
750 			mapbase += alignmask;
751 			mapbase &= ~alignmask;
752 			if (ef->shstrtab != NULL && shdr[i].sh_name != 0) {
753 				ef->progtab[pb].name =
754 				    ef->shstrtab + shdr[i].sh_name;
755 				if (!strcmp(ef->progtab[pb].name, ".ctors")) {
756 					lf->ctors_addr = (caddr_t)mapbase;
757 					lf->ctors_size = shdr[i].sh_size;
758 				}
759 			} else if (shdr[i].sh_type == SHT_PROGBITS)
760 				ef->progtab[pb].name = "<<PROGBITS>>";
761 			else
762 				ef->progtab[pb].name = "<<NOBITS>>";
763 			if (ef->progtab[pb].name != NULL &&
764 			    !strcmp(ef->progtab[pb].name, DPCPU_SETNAME))
765 				ef->progtab[pb].addr =
766 				    dpcpu_alloc(shdr[i].sh_size);
767 #ifdef VIMAGE
768 			else if (ef->progtab[pb].name != NULL &&
769 			    !strcmp(ef->progtab[pb].name, VNET_SETNAME))
770 				ef->progtab[pb].addr =
771 				    vnet_data_alloc(shdr[i].sh_size);
772 #endif
773 			else
774 				ef->progtab[pb].addr =
775 				    (void *)(uintptr_t)mapbase;
776 			if (ef->progtab[pb].addr == NULL) {
777 				error = ENOSPC;
778 				goto out;
779 			}
780 			ef->progtab[pb].size = shdr[i].sh_size;
781 			ef->progtab[pb].sec = i;
782 			if (shdr[i].sh_type == SHT_PROGBITS) {
783 				error = vn_rdwr(UIO_READ, nd.ni_vp,
784 				    ef->progtab[pb].addr,
785 				    shdr[i].sh_size, shdr[i].sh_offset,
786 				    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
787 				    NOCRED, &resid, td);
788 				if (error)
789 					goto out;
790 				if (resid != 0){
791 					error = EINVAL;
792 					goto out;
793 				}
794 				/* Initialize the per-cpu or vnet area. */
795 				if (ef->progtab[pb].addr != (void *)mapbase &&
796 				    !strcmp(ef->progtab[pb].name, DPCPU_SETNAME))
797 					dpcpu_copy(ef->progtab[pb].addr,
798 					    shdr[i].sh_size);
799 #ifdef VIMAGE
800 				else if (ef->progtab[pb].addr !=
801 				    (void *)mapbase &&
802 				    !strcmp(ef->progtab[pb].name, VNET_SETNAME))
803 					vnet_data_copy(ef->progtab[pb].addr,
804 					    shdr[i].sh_size);
805 #endif
806 			} else
807 				bzero(ef->progtab[pb].addr, shdr[i].sh_size);
808 
809 			/* Update all symbol values with the offset. */
810 			for (j = 0; j < ef->ddbsymcnt; j++) {
811 				es = &ef->ddbsymtab[j];
812 				if (es->st_shndx != i)
813 					continue;
814 				es->st_value += (Elf_Addr)ef->progtab[pb].addr;
815 			}
816 			mapbase += shdr[i].sh_size;
817 			pb++;
818 			break;
819 		case SHT_REL:
820 			ef->reltab[rl].rel = malloc(shdr[i].sh_size, M_LINKER,
821 			    M_WAITOK);
822 			ef->reltab[rl].nrel = shdr[i].sh_size / sizeof(Elf_Rel);
823 			ef->reltab[rl].sec = shdr[i].sh_info;
824 			error = vn_rdwr(UIO_READ, nd.ni_vp,
825 			    (void *)ef->reltab[rl].rel,
826 			    shdr[i].sh_size, shdr[i].sh_offset,
827 			    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
828 			    &resid, td);
829 			if (error)
830 				goto out;
831 			if (resid != 0){
832 				error = EINVAL;
833 				goto out;
834 			}
835 			rl++;
836 			break;
837 		case SHT_RELA:
838 			ef->relatab[ra].rela = malloc(shdr[i].sh_size, M_LINKER,
839 			    M_WAITOK);
840 			ef->relatab[ra].nrela =
841 			    shdr[i].sh_size / sizeof(Elf_Rela);
842 			ef->relatab[ra].sec = shdr[i].sh_info;
843 			error = vn_rdwr(UIO_READ, nd.ni_vp,
844 			    (void *)ef->relatab[ra].rela,
845 			    shdr[i].sh_size, shdr[i].sh_offset,
846 			    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
847 			    &resid, td);
848 			if (error)
849 				goto out;
850 			if (resid != 0){
851 				error = EINVAL;
852 				goto out;
853 			}
854 			ra++;
855 			break;
856 		}
857 	}
858 	if (pb != ef->nprogtab)
859 		panic("lost progbits");
860 	if (rl != ef->nreltab)
861 		panic("lost reltab");
862 	if (ra != ef->nrelatab)
863 		panic("lost relatab");
864 	if (mapbase != (vm_offset_t)ef->address + mapsize)
865 		panic("mapbase 0x%lx != address %p + mapsize 0x%lx (0x%lx)\n",
866 		    (u_long)mapbase, ef->address, (u_long)mapsize,
867 		    (u_long)(vm_offset_t)ef->address + mapsize);
868 
869 	/* Local intra-module relocations */
870 	link_elf_reloc_local(lf);
871 
872 	/* Pull in dependencies */
873 	VOP_UNLOCK(nd.ni_vp, 0);
874 	error = linker_load_dependencies(lf);
875 	vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
876 	if (error)
877 		goto out;
878 
879 	/* External relocations */
880 	error = relocate_file(ef);
881 	if (error)
882 		goto out;
883 
884 	/* Notify MD code that a module is being loaded. */
885 	error = elf_cpu_load_file(lf);
886 	if (error)
887 		goto out;
888 
889 	/* Invoke .ctors */
890 	link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
891 
892 	*result = lf;
893 
894 out:
895 	VOP_UNLOCK(nd.ni_vp, 0);
896 	vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
897 	if (error && lf)
898 		linker_file_unload(lf, LINKER_UNLOAD_FORCE);
899 	if (hdr)
900 		free(hdr, M_LINKER);
901 
902 	return error;
903 }
904 
905 static void
906 link_elf_unload_file(linker_file_t file)
907 {
908 	elf_file_t ef = (elf_file_t) file;
909 	int i;
910 
911 	/* Notify MD code that a module is being unloaded. */
912 	elf_cpu_unload_file(file);
913 
914 	if (ef->progtab) {
915 		for (i = 0; i < ef->nprogtab; i++) {
916 			if (ef->progtab[i].size == 0)
917 				continue;
918 			if (ef->progtab[i].name == NULL)
919 				continue;
920 			if (!strcmp(ef->progtab[i].name, DPCPU_SETNAME))
921 				dpcpu_free(ef->progtab[i].addr,
922 				    ef->progtab[i].size);
923 #ifdef VIMAGE
924 			else if (!strcmp(ef->progtab[i].name, VNET_SETNAME))
925 				vnet_data_free(ef->progtab[i].addr,
926 				    ef->progtab[i].size);
927 #endif
928 		}
929 	}
930 	if (ef->preloaded) {
931 		if (ef->reltab)
932 			free(ef->reltab, M_LINKER);
933 		if (ef->relatab)
934 			free(ef->relatab, M_LINKER);
935 		if (ef->progtab)
936 			free(ef->progtab, M_LINKER);
937 		if (ef->ctftab)
938 			free(ef->ctftab, M_LINKER);
939 		if (ef->ctfoff)
940 			free(ef->ctfoff, M_LINKER);
941 		if (ef->typoff)
942 			free(ef->typoff, M_LINKER);
943 		if (file->filename != NULL)
944 			preload_delete_name(file->filename);
945 		/* XXX reclaim module memory? */
946 		return;
947 	}
948 
949 	for (i = 0; i < ef->nreltab; i++)
950 		if (ef->reltab[i].rel)
951 			free(ef->reltab[i].rel, M_LINKER);
952 	for (i = 0; i < ef->nrelatab; i++)
953 		if (ef->relatab[i].rela)
954 			free(ef->relatab[i].rela, M_LINKER);
955 	if (ef->reltab)
956 		free(ef->reltab, M_LINKER);
957 	if (ef->relatab)
958 		free(ef->relatab, M_LINKER);
959 	if (ef->progtab)
960 		free(ef->progtab, M_LINKER);
961 
962 	if (ef->object) {
963 		vm_map_remove(kernel_map, (vm_offset_t) ef->address,
964 		    (vm_offset_t) ef->address +
965 		    (ef->object->size << PAGE_SHIFT));
966 	}
967 	if (ef->e_shdr)
968 		free(ef->e_shdr, M_LINKER);
969 	if (ef->ddbsymtab)
970 		free(ef->ddbsymtab, M_LINKER);
971 	if (ef->ddbstrtab)
972 		free(ef->ddbstrtab, M_LINKER);
973 	if (ef->shstrtab)
974 		free(ef->shstrtab, M_LINKER);
975 	if (ef->ctftab)
976 		free(ef->ctftab, M_LINKER);
977 	if (ef->ctfoff)
978 		free(ef->ctfoff, M_LINKER);
979 	if (ef->typoff)
980 		free(ef->typoff, M_LINKER);
981 }
982 
983 static const char *
984 symbol_name(elf_file_t ef, Elf_Size r_info)
985 {
986 	const Elf_Sym *ref;
987 
988 	if (ELF_R_SYM(r_info)) {
989 		ref = ef->ddbsymtab + ELF_R_SYM(r_info);
990 		return ef->ddbstrtab + ref->st_name;
991 	} else
992 		return NULL;
993 }
994 
995 static Elf_Addr
996 findbase(elf_file_t ef, int sec)
997 {
998 	int i;
999 	Elf_Addr base = 0;
1000 
1001 	for (i = 0; i < ef->nprogtab; i++) {
1002 		if (sec == ef->progtab[i].sec) {
1003 			base = (Elf_Addr)ef->progtab[i].addr;
1004 			break;
1005 		}
1006 	}
1007 	return base;
1008 }
1009 
1010 static int
1011 relocate_file(elf_file_t ef)
1012 {
1013 	const Elf_Rel *rellim;
1014 	const Elf_Rel *rel;
1015 	const Elf_Rela *relalim;
1016 	const Elf_Rela *rela;
1017 	const char *symname;
1018 	const Elf_Sym *sym;
1019 	int i;
1020 	Elf_Size symidx;
1021 	Elf_Addr base;
1022 
1023 
1024 	/* Perform relocations without addend if there are any: */
1025 	for (i = 0; i < ef->nreltab; i++) {
1026 		rel = ef->reltab[i].rel;
1027 		if (rel == NULL)
1028 			panic("lost a reltab!");
1029 		rellim = rel + ef->reltab[i].nrel;
1030 		base = findbase(ef, ef->reltab[i].sec);
1031 		if (base == 0)
1032 			panic("lost base for reltab");
1033 		for ( ; rel < rellim; rel++) {
1034 			symidx = ELF_R_SYM(rel->r_info);
1035 			if (symidx >= ef->ddbsymcnt)
1036 				continue;
1037 			sym = ef->ddbsymtab + symidx;
1038 			/* Local relocs are already done */
1039 			if (ELF_ST_BIND(sym->st_info) == STB_LOCAL)
1040 				continue;
1041 			if (elf_reloc(&ef->lf, base, rel, ELF_RELOC_REL,
1042 			    elf_obj_lookup)) {
1043 				symname = symbol_name(ef, rel->r_info);
1044 				printf("link_elf_obj: symbol %s undefined\n",
1045 				    symname);
1046 				return ENOENT;
1047 			}
1048 		}
1049 	}
1050 
1051 	/* Perform relocations with addend if there are any: */
1052 	for (i = 0; i < ef->nrelatab; i++) {
1053 		rela = ef->relatab[i].rela;
1054 		if (rela == NULL)
1055 			panic("lost a relatab!");
1056 		relalim = rela + ef->relatab[i].nrela;
1057 		base = findbase(ef, ef->relatab[i].sec);
1058 		if (base == 0)
1059 			panic("lost base for relatab");
1060 		for ( ; rela < relalim; rela++) {
1061 			symidx = ELF_R_SYM(rela->r_info);
1062 			if (symidx >= ef->ddbsymcnt)
1063 				continue;
1064 			sym = ef->ddbsymtab + symidx;
1065 			/* Local relocs are already done */
1066 			if (ELF_ST_BIND(sym->st_info) == STB_LOCAL)
1067 				continue;
1068 			if (elf_reloc(&ef->lf, base, rela, ELF_RELOC_RELA,
1069 			    elf_obj_lookup)) {
1070 				symname = symbol_name(ef, rela->r_info);
1071 				printf("link_elf_obj: symbol %s undefined\n",
1072 				    symname);
1073 				return ENOENT;
1074 			}
1075 		}
1076 	}
1077 
1078 	return 0;
1079 }
1080 
1081 static int
1082 link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
1083 {
1084 	elf_file_t ef = (elf_file_t) lf;
1085 	const Elf_Sym *symp;
1086 	const char *strp;
1087 	int i;
1088 
1089 	for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1090 		strp = ef->ddbstrtab + symp->st_name;
1091 		if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) {
1092 			*sym = (c_linker_sym_t) symp;
1093 			return 0;
1094 		}
1095 	}
1096 	return ENOENT;
1097 }
1098 
1099 static int
1100 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
1101     linker_symval_t *symval)
1102 {
1103 	elf_file_t ef = (elf_file_t) lf;
1104 	const Elf_Sym *es = (const Elf_Sym*) sym;
1105 
1106 	if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1107 		symval->name = ef->ddbstrtab + es->st_name;
1108 		symval->value = (caddr_t)es->st_value;
1109 		symval->size = es->st_size;
1110 		return 0;
1111 	}
1112 	return ENOENT;
1113 }
1114 
1115 static int
1116 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1117     c_linker_sym_t *sym, long *diffp)
1118 {
1119 	elf_file_t ef = (elf_file_t) lf;
1120 	u_long off = (uintptr_t) (void *) value;
1121 	u_long diff = off;
1122 	u_long st_value;
1123 	const Elf_Sym *es;
1124 	const Elf_Sym *best = 0;
1125 	int i;
1126 
1127 	for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1128 		if (es->st_name == 0)
1129 			continue;
1130 		st_value = es->st_value;
1131 		if (off >= st_value) {
1132 			if (off - st_value < diff) {
1133 				diff = off - st_value;
1134 				best = es;
1135 				if (diff == 0)
1136 					break;
1137 			} else if (off - st_value == diff) {
1138 				best = es;
1139 			}
1140 		}
1141 	}
1142 	if (best == 0)
1143 		*diffp = off;
1144 	else
1145 		*diffp = diff;
1146 	*sym = (c_linker_sym_t) best;
1147 
1148 	return 0;
1149 }
1150 
1151 /*
1152  * Look up a linker set on an ELF system.
1153  */
1154 static int
1155 link_elf_lookup_set(linker_file_t lf, const char *name,
1156     void ***startp, void ***stopp, int *countp)
1157 {
1158 	elf_file_t ef = (elf_file_t)lf;
1159 	void **start, **stop;
1160 	int i, count;
1161 
1162 	/* Relative to section number */
1163 	for (i = 0; i < ef->nprogtab; i++) {
1164 		if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) &&
1165 		    strcmp(ef->progtab[i].name + 4, name) == 0) {
1166 			start  = (void **)ef->progtab[i].addr;
1167 			stop = (void **)((char *)ef->progtab[i].addr +
1168 			    ef->progtab[i].size);
1169 			count = stop - start;
1170 			if (startp)
1171 				*startp = start;
1172 			if (stopp)
1173 				*stopp = stop;
1174 			if (countp)
1175 				*countp = count;
1176 			return (0);
1177 		}
1178 	}
1179 	return (ESRCH);
1180 }
1181 
1182 static int
1183 link_elf_each_function_name(linker_file_t file,
1184     int (*callback)(const char *, void *), void *opaque)
1185 {
1186 	elf_file_t ef = (elf_file_t)file;
1187 	const Elf_Sym *symp;
1188 	int i, error;
1189 
1190 	/* Exhaustive search */
1191 	for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1192 		if (symp->st_value != 0 &&
1193 		    ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1194 			error = callback(ef->ddbstrtab + symp->st_name, opaque);
1195 			if (error)
1196 				return (error);
1197 		}
1198 	}
1199 	return (0);
1200 }
1201 
1202 static int
1203 link_elf_each_function_nameval(linker_file_t file,
1204     linker_function_nameval_callback_t callback, void *opaque)
1205 {
1206 	linker_symval_t symval;
1207 	elf_file_t ef = (elf_file_t)file;
1208 	const Elf_Sym* symp;
1209 	int i, error;
1210 
1211 	/* Exhaustive search */
1212 	for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1213 		if (symp->st_value != 0 &&
1214 		    ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1215 			error = link_elf_symbol_values(file, (c_linker_sym_t) symp, &symval);
1216 			if (error)
1217 				return (error);
1218 			error = callback(file, i, &symval, opaque);
1219 			if (error)
1220 				return (error);
1221 		}
1222 	}
1223 	return (0);
1224 }
1225 
1226 /*
1227  * Symbol lookup function that can be used when the symbol index is known (ie
1228  * in relocations). It uses the symbol index instead of doing a fully fledged
1229  * hash table based lookup when such is valid. For example for local symbols.
1230  * This is not only more efficient, it's also more correct. It's not always
1231  * the case that the symbol can be found through the hash table.
1232  */
1233 static Elf_Addr
1234 elf_obj_lookup(linker_file_t lf, Elf_Size symidx, int deps)
1235 {
1236 	elf_file_t ef = (elf_file_t)lf;
1237 	const Elf_Sym *sym;
1238 	const char *symbol;
1239 	Elf_Addr ret;
1240 
1241 	/* Don't even try to lookup the symbol if the index is bogus. */
1242 	if (symidx >= ef->ddbsymcnt)
1243 		return (0);
1244 
1245 	sym = ef->ddbsymtab + symidx;
1246 
1247 	/* Quick answer if there is a definition included. */
1248 	if (sym->st_shndx != SHN_UNDEF)
1249 		return (sym->st_value);
1250 
1251 	/* If we get here, then it is undefined and needs a lookup. */
1252 	switch (ELF_ST_BIND(sym->st_info)) {
1253 	case STB_LOCAL:
1254 		/* Local, but undefined? huh? */
1255 		return (0);
1256 
1257 	case STB_GLOBAL:
1258 		/* Relative to Data or Function name */
1259 		symbol = ef->ddbstrtab + sym->st_name;
1260 
1261 		/* Force a lookup failure if the symbol name is bogus. */
1262 		if (*symbol == 0)
1263 			return (0);
1264 		ret = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1265 		return ret;
1266 
1267 	case STB_WEAK:
1268 		printf("link_elf_obj: Weak symbols not supported\n");
1269 		return (0);
1270 
1271 	default:
1272 		return (0);
1273 	}
1274 }
1275 
1276 static void
1277 link_elf_fix_link_set(elf_file_t ef)
1278 {
1279 	static const char startn[] = "__start_";
1280 	static const char stopn[] = "__stop_";
1281 	Elf_Sym *sym;
1282 	const char *sym_name, *linkset_name;
1283 	Elf_Addr startp, stopp;
1284 	Elf_Size symidx;
1285 	int start, i;
1286 
1287 	startp = stopp = 0;
1288 	for (symidx = 1 /* zero entry is special */;
1289 		symidx < ef->ddbsymcnt; symidx++) {
1290 		sym = ef->ddbsymtab + symidx;
1291 		if (sym->st_shndx != SHN_UNDEF)
1292 			continue;
1293 
1294 		sym_name = ef->ddbstrtab + sym->st_name;
1295 		if (strncmp(sym_name, startn, sizeof(startn) - 1) == 0) {
1296 			start = 1;
1297 			linkset_name = sym_name + sizeof(startn) - 1;
1298 		}
1299 		else if (strncmp(sym_name, stopn, sizeof(stopn) - 1) == 0) {
1300 			start = 0;
1301 			linkset_name = sym_name + sizeof(stopn) - 1;
1302 		}
1303 		else
1304 			continue;
1305 
1306 		for (i = 0; i < ef->nprogtab; i++) {
1307 			if (strcmp(ef->progtab[i].name, linkset_name) == 0) {
1308 				startp = (Elf_Addr)ef->progtab[i].addr;
1309 				stopp = (Elf_Addr)(startp + ef->progtab[i].size);
1310 				break;
1311 			}
1312 		}
1313 		if (i == ef->nprogtab)
1314 			continue;
1315 
1316 		sym->st_value = start ? startp : stopp;
1317 		sym->st_shndx = i;
1318 	}
1319 }
1320 
1321 static void
1322 link_elf_reloc_local(linker_file_t lf)
1323 {
1324 	elf_file_t ef = (elf_file_t)lf;
1325 	const Elf_Rel *rellim;
1326 	const Elf_Rel *rel;
1327 	const Elf_Rela *relalim;
1328 	const Elf_Rela *rela;
1329 	const Elf_Sym *sym;
1330 	Elf_Addr base;
1331 	int i;
1332 	Elf_Size symidx;
1333 
1334 	link_elf_fix_link_set(ef);
1335 
1336 	/* Perform relocations without addend if there are any: */
1337 	for (i = 0; i < ef->nreltab; i++) {
1338 		rel = ef->reltab[i].rel;
1339 		if (rel == NULL)
1340 			panic("lost a reltab!");
1341 		rellim = rel + ef->reltab[i].nrel;
1342 		base = findbase(ef, ef->reltab[i].sec);
1343 		if (base == 0)
1344 			panic("lost base for reltab");
1345 		for ( ; rel < rellim; rel++) {
1346 			symidx = ELF_R_SYM(rel->r_info);
1347 			if (symidx >= ef->ddbsymcnt)
1348 				continue;
1349 			sym = ef->ddbsymtab + symidx;
1350 			/* Only do local relocs */
1351 			if (ELF_ST_BIND(sym->st_info) != STB_LOCAL)
1352 				continue;
1353 			elf_reloc_local(lf, base, rel, ELF_RELOC_REL,
1354 			    elf_obj_lookup);
1355 		}
1356 	}
1357 
1358 	/* Perform relocations with addend if there are any: */
1359 	for (i = 0; i < ef->nrelatab; i++) {
1360 		rela = ef->relatab[i].rela;
1361 		if (rela == NULL)
1362 			panic("lost a relatab!");
1363 		relalim = rela + ef->relatab[i].nrela;
1364 		base = findbase(ef, ef->relatab[i].sec);
1365 		if (base == 0)
1366 			panic("lost base for relatab");
1367 		for ( ; rela < relalim; rela++) {
1368 			symidx = ELF_R_SYM(rela->r_info);
1369 			if (symidx >= ef->ddbsymcnt)
1370 				continue;
1371 			sym = ef->ddbsymtab + symidx;
1372 			/* Only do local relocs */
1373 			if (ELF_ST_BIND(sym->st_info) != STB_LOCAL)
1374 				continue;
1375 			elf_reloc_local(lf, base, rela, ELF_RELOC_RELA,
1376 			    elf_obj_lookup);
1377 		}
1378 	}
1379 }
1380 
1381 static long
1382 link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
1383 {
1384     elf_file_t ef = (elf_file_t)lf;
1385 
1386     *symtab = ef->ddbsymtab;
1387 
1388     if (*symtab == NULL)
1389         return (0);
1390 
1391     return (ef->ddbsymcnt);
1392 }
1393 
1394 static long
1395 link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
1396 {
1397     elf_file_t ef = (elf_file_t)lf;
1398 
1399     *strtab = ef->ddbstrtab;
1400 
1401     if (*strtab == NULL)
1402         return (0);
1403 
1404     return (ef->ddbstrcnt);
1405 }
1406