link_elf.c revision 81500 
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 * $FreeBSD: head/sys/kern/link_elf.c 81500 2001-08-10 23:15:13Z wpaul $
27 */
28
29#include "opt_ddb.h"
30
31#include <sys/param.h>
32#include <sys/systm.h>
33#include <sys/kernel.h>
34#include <sys/lock.h>
35#include <sys/malloc.h>
36#include <sys/mutex.h>
37#include <sys/proc.h>
38#include <sys/namei.h>
39#include <sys/fcntl.h>
40#include <sys/vnode.h>
41#include <sys/linker.h>
42
43#include <machine/elf.h>
44
45#include <vm/vm.h>
46#include <vm/vm_param.h>
47#ifdef SPARSE_MAPPING
48#include <vm/vm_object.h>
49#include <vm/vm_kern.h>
50#include <vm/vm_extern.h>
51#endif
52#include <vm/pmap.h>
53#include <vm/vm_map.h>
54
55#ifdef __AOUT__
56#include <nlist.h>
57#endif
58#include <link.h>
59
60#include "linker_if.h"
61
62typedef struct elf_file {
63    struct linker_file	lf;		/* Common fields */
64    int			preloaded;	/* Was file pre-loaded */
65    caddr_t		address;	/* Relocation address */
66#ifdef SPARSE_MAPPING
67    vm_object_t		object;		/* VM object to hold file pages */
68#endif
69    Elf_Dyn*		dynamic;	/* Symbol table etc. */
70    Elf_Hashelt		nbuckets;	/* DT_HASH info */
71    Elf_Hashelt		nchains;
72    const Elf_Hashelt*	buckets;
73    const Elf_Hashelt*	chains;
74    caddr_t		hash;
75    caddr_t		strtab;		/* DT_STRTAB */
76    int			strsz;		/* DT_STRSZ */
77    const Elf_Sym*	symtab;		/* DT_SYMTAB */
78    Elf_Addr*		got;		/* DT_PLTGOT */
79    const Elf_Rel*	pltrel;		/* DT_JMPREL */
80    int			pltrelsize;	/* DT_PLTRELSZ */
81    const Elf_Rela*	pltrela;	/* DT_JMPREL */
82    int			pltrelasize;	/* DT_PLTRELSZ */
83    const Elf_Rel*	rel;		/* DT_REL */
84    int			relsize;	/* DT_RELSZ */
85    const Elf_Rela*	rela;		/* DT_RELA */
86    int			relasize;	/* DT_RELASZ */
87    caddr_t		modptr;
88    const Elf_Sym*	ddbsymtab;	/* The symbol table we are using */
89    long		ddbsymcnt;	/* Number of symbols */
90    caddr_t		ddbstrtab;	/* String table */
91    long		ddbstrcnt;	/* number of bytes in string table */
92    caddr_t		symbase;	/* malloc'ed symbold base */
93    caddr_t		strbase;	/* malloc'ed string base */
94#ifdef DDB
95    struct link_map	gdb;		/* hooks for gdb */
96#endif
97} *elf_file_t;
98
99static int	link_elf_link_preload(linker_class_t cls,
100				      const char*, linker_file_t*);
101static int	link_elf_link_preload_finish(linker_file_t);
102static int	link_elf_load_file(linker_class_t, const char*, linker_file_t*);
103static int	link_elf_lookup_symbol(linker_file_t, const char*,
104				       c_linker_sym_t*);
105static int	link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
106static int	link_elf_search_symbol(linker_file_t, caddr_t value,
107				       c_linker_sym_t* sym, long* diffp);
108
109static void	link_elf_unload_file(linker_file_t);
110static void	link_elf_unload_preload(linker_file_t);
111static int	link_elf_lookup_set(linker_file_t, const char *,
112				    void ***, void ***, int *);
113
114static kobj_method_t link_elf_methods[] = {
115    KOBJMETHOD(linker_lookup_symbol,	link_elf_lookup_symbol),
116    KOBJMETHOD(linker_symbol_values,	link_elf_symbol_values),
117    KOBJMETHOD(linker_search_symbol,	link_elf_search_symbol),
118    KOBJMETHOD(linker_unload,		link_elf_unload_file),
119    KOBJMETHOD(linker_load_file,	link_elf_load_file),
120    KOBJMETHOD(linker_link_preload,	link_elf_link_preload),
121    KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
122    KOBJMETHOD(linker_lookup_set,	link_elf_lookup_set),
123    { 0, 0 }
124};
125
126static struct linker_class link_elf_class = {
127#if ELF_TARG_CLASS == ELFCLASS32
128    "elf32",
129#else
130    "elf64",
131#endif
132    link_elf_methods, sizeof(struct elf_file)
133};
134
135static int		parse_dynamic(elf_file_t ef);
136static int		relocate_file(elf_file_t ef);
137static int		link_elf_preload_parse_symbols(elf_file_t ef);
138
139#ifdef DDB
140static void		r_debug_state(struct r_debug *dummy_one,
141				      struct link_map *dummy_two);
142
143/*
144 * A list of loaded modules for GDB to use for loading symbols.
145 */
146struct r_debug r_debug;
147
148#define GDB_STATE(s)	r_debug.r_state = s; r_debug_state(NULL, NULL);
149
150/*
151 * Function for the debugger to set a breakpoint on to gain control.
152 */
153void
154r_debug_state(struct r_debug *dummy_one __unused,
155	      struct link_map *dummy_two __unused)
156{
157}
158
159#endif
160
161/*
162 * The kernel symbol table starts here.
163 */
164#ifndef __ia64__
165extern struct _dynamic _DYNAMIC;
166#endif
167
168static void
169link_elf_init(void* arg)
170{
171#ifdef __ELF__
172    Elf_Dyn	*dp;
173    caddr_t	modptr, baseptr, sizeptr;
174    elf_file_t	ef;
175    char	*modname;
176#ifdef DDB
177    char *newfilename;
178#endif
179#endif
180
181    linker_add_class(&link_elf_class);
182
183#ifdef __ELF__
184#ifndef __ia64__
185    dp = (Elf_Dyn*) &_DYNAMIC;
186#else
187    dp = 0;
188#endif
189    if (dp) {
190	modname = NULL;
191	modptr = preload_search_by_type("elf kernel");
192	if (modptr)
193	    modname = (char *)preload_search_info(modptr, MODINFO_NAME);
194	if (modname == NULL)
195	    modname = "kernel";
196	linker_kernel_file = linker_make_file(modname, &link_elf_class);
197	if (linker_kernel_file == NULL)
198	    panic("link_elf_init: Can't create linker structures for kernel");
199
200	ef = (elf_file_t) linker_kernel_file;
201	ef->preloaded = 1;
202	ef->address = 0;
203#ifdef SPARSE_MAPPING
204	ef->object = 0;
205#endif
206	ef->dynamic = dp;
207
208	parse_dynamic(ef);
209	linker_kernel_file->address = (caddr_t) KERNBASE;
210	linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
211
212	if (modptr) {
213	    ef->modptr = modptr;
214	    baseptr = preload_search_info(modptr, MODINFO_ADDR);
215	    if (baseptr)
216		linker_kernel_file->address = *(caddr_t *)baseptr;
217	    sizeptr = preload_search_info(modptr, MODINFO_SIZE);
218	    if (sizeptr)
219		linker_kernel_file->size = *(size_t *)sizeptr;
220	}
221	(void)link_elf_preload_parse_symbols(ef);
222
223#ifdef DDB
224	ef->gdb.l_addr = linker_kernel_file->address;
225	newfilename = malloc(strlen(modname) + 1, M_LINKER, M_WAITOK);
226	strcpy(newfilename, modname);
227	ef->gdb.l_name = newfilename;
228	ef->gdb.l_ld = dp;
229	ef->gdb.l_prev = 0;
230	ef->gdb.l_next = 0;
231
232	r_debug.r_map = &ef->gdb;
233	r_debug.r_brk = r_debug_state;
234	r_debug.r_state = RT_CONSISTENT;
235
236	r_debug_state(NULL, NULL);	/* say hello to gdb! */
237#endif
238
239    }
240#endif
241}
242
243SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
244
245static int
246link_elf_preload_parse_symbols(elf_file_t ef)
247{
248    caddr_t	pointer;
249    caddr_t	ssym, esym, base;
250    caddr_t	strtab;
251    int		strcnt;
252    Elf_Sym*	symtab;
253    int		symcnt;
254
255    if (ef->modptr == NULL)
256	return 0;
257    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
258    if (pointer == NULL)
259	return 0;
260    ssym = *(caddr_t *)pointer;
261    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
262    if (pointer == NULL)
263	return 0;
264    esym = *(caddr_t *)pointer;
265
266    base = ssym;
267
268    symcnt = *(long *)base;
269    base += sizeof(long);
270    symtab = (Elf_Sym *)base;
271    base += roundup(symcnt, sizeof(long));
272
273    if (base > esym || base < ssym) {
274	printf("Symbols are corrupt!\n");
275	return EINVAL;
276    }
277
278    strcnt = *(long *)base;
279    base += sizeof(long);
280    strtab = base;
281    base += roundup(strcnt, sizeof(long));
282
283    if (base > esym || base < ssym) {
284	printf("Symbols are corrupt!\n");
285	return EINVAL;
286    }
287
288    ef->ddbsymtab = symtab;
289    ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
290    ef->ddbstrtab = strtab;
291    ef->ddbstrcnt = strcnt;
292
293    return 0;
294}
295
296static int
297parse_dynamic(elf_file_t ef)
298{
299    Elf_Dyn *dp;
300    int plttype = DT_REL;
301
302    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
303	switch (dp->d_tag) {
304	case DT_HASH:
305	{
306	    /* From src/libexec/rtld-elf/rtld.c */
307	    const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
308		(ef->address + dp->d_un.d_ptr);
309	    ef->nbuckets = hashtab[0];
310	    ef->nchains = hashtab[1];
311	    ef->buckets = hashtab + 2;
312	    ef->chains = ef->buckets + ef->nbuckets;
313	    break;
314	}
315	case DT_STRTAB:
316	    ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
317	    break;
318	case DT_STRSZ:
319	    ef->strsz = dp->d_un.d_val;
320	    break;
321	case DT_SYMTAB:
322	    ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
323	    break;
324	case DT_SYMENT:
325	    if (dp->d_un.d_val != sizeof(Elf_Sym))
326		return ENOEXEC;
327	    break;
328	case DT_PLTGOT:
329	    ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
330	    break;
331	case DT_REL:
332	    ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
333	    break;
334	case DT_RELSZ:
335	    ef->relsize = dp->d_un.d_val;
336	    break;
337	case DT_RELENT:
338	    if (dp->d_un.d_val != sizeof(Elf_Rel))
339		return ENOEXEC;
340	    break;
341	case DT_JMPREL:
342	    ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
343	    break;
344	case DT_PLTRELSZ:
345	    ef->pltrelsize = dp->d_un.d_val;
346	    break;
347	case DT_RELA:
348	    ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
349	    break;
350	case DT_RELASZ:
351	    ef->relasize = dp->d_un.d_val;
352	    break;
353	case DT_RELAENT:
354	    if (dp->d_un.d_val != sizeof(Elf_Rela))
355		return ENOEXEC;
356	    break;
357	case DT_PLTREL:
358	    plttype = dp->d_un.d_val;
359	    if (plttype != DT_REL && plttype != DT_RELA)
360		return ENOEXEC;
361	    break;
362#ifdef DDB
363	case DT_DEBUG:
364	    dp->d_un.d_ptr = (Elf_Addr) &r_debug;
365	    break;
366#endif
367	}
368    }
369
370    if (plttype == DT_RELA) {
371	ef->pltrela = (const Elf_Rela *) ef->pltrel;
372	ef->pltrel = NULL;
373	ef->pltrelasize = ef->pltrelsize;
374	ef->pltrelsize = 0;
375    }
376
377    ef->ddbsymtab = ef->symtab;
378    ef->ddbsymcnt = ef->nchains;
379    ef->ddbstrtab = ef->strtab;
380    ef->ddbstrcnt = ef->strsz;
381
382    return 0;
383}
384
385static void
386link_elf_error(const char *s)
387{
388    printf("kldload: %s\n", s);
389}
390
391#ifdef DDB
392
393static void
394link_elf_add_gdb(struct link_map *l)
395{
396    struct link_map *prev;
397
398    /*
399     * Scan to the end of the list.
400     */
401    for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
402	;
403
404    /* Link in the new entry. */
405    l->l_prev = prev;
406    l->l_next = prev->l_next;
407    prev->l_next = l;
408}
409
410static void
411link_elf_delete_gdb(struct link_map *l)
412{
413    if (l->l_prev == NULL) {
414	if ((r_debug.r_map = l->l_next) != NULL)
415	    l->l_next->l_prev = NULL;
416	return;
417    }
418
419    if ((l->l_prev->l_next = l->l_next) != NULL)
420	l->l_next->l_prev = l->l_prev;
421}
422
423#endif /* DDB */
424
425static int
426link_elf_link_preload(linker_class_t cls,
427		      const char* filename, linker_file_t *result)
428{
429    caddr_t		modptr, baseptr, sizeptr, dynptr;
430    char		*type;
431    elf_file_t		ef;
432    linker_file_t	lf;
433    int			error;
434    vm_offset_t		dp;
435
436    /* Look to see if we have the file preloaded */
437    modptr = preload_search_by_name(filename);
438    if (modptr == NULL)
439	return ENOENT;
440
441    type = (char *)preload_search_info(modptr, MODINFO_TYPE);
442    baseptr = preload_search_info(modptr, MODINFO_ADDR);
443    sizeptr = preload_search_info(modptr, MODINFO_SIZE);
444    dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
445    if (type == NULL || strcmp(type, "elf module") != 0)
446	return (EFTYPE);
447    if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
448	return (EINVAL);
449
450    lf = linker_make_file(filename, &link_elf_class);
451    if (lf == NULL) {
452	return ENOMEM;
453    }
454
455    ef = (elf_file_t) lf;
456    ef->preloaded = 1;
457    ef->modptr = modptr;
458    ef->address = *(caddr_t *)baseptr;
459#ifdef SPARSE_MAPPING
460    ef->object = 0;
461#endif
462    dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
463    ef->dynamic = (Elf_Dyn *)dp;
464    lf->address = ef->address;
465    lf->size = *(size_t *)sizeptr;
466
467    error = parse_dynamic(ef);
468    if (error) {
469	linker_file_unload(lf);
470	return error;
471    }
472    *result = lf;
473    return (0);
474}
475
476static int
477link_elf_link_preload_finish(linker_file_t lf)
478{
479    elf_file_t		ef;
480    int error;
481#ifdef DDB
482    char *newfilename;
483#endif
484
485    ef = (elf_file_t) lf;
486#if 0	/* this will be more trouble than it's worth for now */
487    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
488	if (dp->d_tag != DT_NEEDED)
489	    continue;
490	modname = ef->strtab + dp->d_un.d_val;
491	error = linker_load_module(modname, lf);
492	if (error)
493	    goto out;
494    }
495#endif
496    error = relocate_file(ef);
497    if (error)
498	return error;
499    (void)link_elf_preload_parse_symbols(ef);
500
501#ifdef DDB
502    GDB_STATE(RT_ADD);
503    ef->gdb.l_addr = lf->address;
504    newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
505    strcpy(newfilename, lf->filename);
506    ef->gdb.l_name = newfilename;
507    ef->gdb.l_ld = ef->dynamic;
508    link_elf_add_gdb(&ef->gdb);
509    GDB_STATE(RT_CONSISTENT);
510#endif
511
512    return (0);
513}
514
515static int
516link_elf_load_file(linker_class_t cls, const char* filename, linker_file_t* result)
517{
518    struct nameidata nd;
519    struct proc* p = curproc;	/* XXX */
520    Elf_Ehdr *hdr;
521    caddr_t firstpage;
522    int nbytes, i;
523    Elf_Phdr *phdr;
524    Elf_Phdr *phlimit;
525    Elf_Phdr *segs[2];
526    int nsegs;
527    Elf_Phdr *phdyn;
528    Elf_Phdr *phphdr;
529    caddr_t mapbase;
530    size_t mapsize;
531    Elf_Off base_offset;
532    Elf_Addr base_vaddr;
533    Elf_Addr base_vlimit;
534    int error = 0;
535    int resid, flags;
536    elf_file_t ef;
537    linker_file_t lf;
538    Elf_Shdr *shdr;
539    int symtabindex;
540    int symstrindex;
541    int symcnt;
542    int strcnt;
543#ifdef DDB
544    char *newfilename;
545#endif
546
547    GIANT_REQUIRED;
548
549    shdr = NULL;
550    lf = NULL;
551
552    NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, p);
553    flags = FREAD;
554    error = vn_open(&nd, &flags, 0);
555    if (error)
556	return error;
557    NDFREE(&nd, NDF_ONLY_PNBUF);
558
559    /*
560     * Read the elf header from the file.
561     */
562    firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
563    if (firstpage == NULL) {
564	error = ENOMEM;
565	goto out;
566    }
567    hdr = (Elf_Ehdr *)firstpage;
568    error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
569		    UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
570    nbytes = PAGE_SIZE - resid;
571    if (error)
572	goto out;
573
574    if (!IS_ELF(*hdr)) {
575	error = ENOEXEC;
576	goto out;
577    }
578
579    if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
580      || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
581	link_elf_error("Unsupported file layout");
582	error = ENOEXEC;
583	goto out;
584    }
585    if (hdr->e_ident[EI_VERSION] != EV_CURRENT
586      || hdr->e_version != EV_CURRENT) {
587	link_elf_error("Unsupported file version");
588	error = ENOEXEC;
589	goto out;
590    }
591    if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
592	link_elf_error("Unsupported file type");
593	error = ENOEXEC;
594	goto out;
595    }
596    if (hdr->e_machine != ELF_TARG_MACH) {
597	link_elf_error("Unsupported machine");
598	error = ENOEXEC;
599	goto out;
600    }
601
602    /*
603     * We rely on the program header being in the first page.  This is
604     * not strictly required by the ABI specification, but it seems to
605     * always true in practice.  And, it simplifies things considerably.
606     */
607    if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
608	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
609	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
610	link_elf_error("Unreadable program headers");
611
612    /*
613     * Scan the program header entries, and save key information.
614     *
615     * We rely on there being exactly two load segments, text and data,
616     * in that order.
617     */
618    phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
619    phlimit = phdr + hdr->e_phnum;
620    nsegs = 0;
621    phdyn = NULL;
622    phphdr = NULL;
623    while (phdr < phlimit) {
624	switch (phdr->p_type) {
625
626	case PT_LOAD:
627	    if (nsegs == 2) {
628		link_elf_error("Too many sections");
629		error = ENOEXEC;
630		goto out;
631	    }
632	    segs[nsegs] = phdr;
633	    ++nsegs;
634	    break;
635
636	case PT_PHDR:
637	    phphdr = phdr;
638	    break;
639
640	case PT_DYNAMIC:
641	    phdyn = phdr;
642	    break;
643
644	case PT_INTERP:
645	    link_elf_error("Unsupported file type");
646	    error = ENOEXEC;
647	    goto out;
648	}
649
650	++phdr;
651    }
652    if (phdyn == NULL) {
653	link_elf_error("Object is not dynamically-linked");
654	error = ENOEXEC;
655	goto out;
656    }
657
658    /*
659     * Allocate the entire address space of the object, to stake out our
660     * contiguous region, and to establish the base address for relocation.
661     */
662    base_offset = trunc_page(segs[0]->p_offset);
663    base_vaddr = trunc_page(segs[0]->p_vaddr);
664    base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
665    mapsize = base_vlimit - base_vaddr;
666
667    lf = linker_make_file(filename, &link_elf_class);
668    if (!lf) {
669	error = ENOMEM;
670	goto out;
671    }
672
673    ef = (elf_file_t) lf;
674#ifdef SPARSE_MAPPING
675    ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
676    if (ef->object == NULL) {
677	free(ef, M_LINKER);
678	error = ENOMEM;
679	goto out;
680    }
681    vm_object_reference(ef->object);
682    ef->address = (caddr_t) vm_map_min(kernel_map);
683    error = vm_map_find(kernel_map, ef->object, 0,
684			(vm_offset_t *) &ef->address,
685			mapsize, 1,
686			VM_PROT_ALL, VM_PROT_ALL, 0);
687    if (error) {
688	vm_object_deallocate(ef->object);
689	ef->object = 0;
690	goto out;
691    }
692#else
693    ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
694    if (!ef->address) {
695	error = ENOMEM;
696	goto out;
697    }
698#endif
699    mapbase = ef->address;
700
701    /*
702     * Read the text and data sections and zero the bss.
703     */
704    for (i = 0; i < 2; i++) {
705	caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
706	error = vn_rdwr(UIO_READ, nd.ni_vp,
707			segbase, segs[i]->p_filesz, segs[i]->p_offset,
708			UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
709	if (error) {
710	    goto out;
711	}
712	bzero(segbase + segs[i]->p_filesz,
713	      segs[i]->p_memsz - segs[i]->p_filesz);
714
715#ifdef SPARSE_MAPPING
716	/*
717	 * Wire down the pages
718	 */
719	vm_map_pageable(kernel_map,
720			(vm_offset_t) segbase,
721			(vm_offset_t) segbase + segs[i]->p_memsz,
722			FALSE);
723#endif
724    }
725
726    ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
727
728    lf->address = ef->address;
729    lf->size = mapsize;
730
731    error = parse_dynamic(ef);
732    if (error)
733	goto out;
734    error = linker_load_dependancies(lf);
735    if (error)
736	goto out;
737#if 0	/* this will be more trouble than it's worth for now */
738    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
739	if (dp->d_tag != DT_NEEDED)
740	    continue;
741	modname = ef->strtab + dp->d_un.d_val;
742	error = linker_load_module(modname, lf);
743	if (error)
744	    goto out;
745    }
746#endif
747    error = relocate_file(ef);
748    if (error)
749	goto out;
750
751    /* Try and load the symbol table if it's present.  (you can strip it!) */
752    nbytes = hdr->e_shnum * hdr->e_shentsize;
753    if (nbytes == 0 || hdr->e_shoff == 0)
754	goto nosyms;
755    shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
756    if (shdr == NULL) {
757	error = ENOMEM;
758	goto out;
759    }
760    error = vn_rdwr(UIO_READ, nd.ni_vp,
761		    (caddr_t)shdr, nbytes, hdr->e_shoff,
762		    UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
763    if (error)
764	goto out;
765    symtabindex = -1;
766    symstrindex = -1;
767    for (i = 0; i < hdr->e_shnum; i++) {
768	if (shdr[i].sh_type == SHT_SYMTAB) {
769	    symtabindex = i;
770	    symstrindex = shdr[i].sh_link;
771	}
772    }
773    if (symtabindex < 0 || symstrindex < 0)
774	goto nosyms;
775
776    symcnt = shdr[symtabindex].sh_size;
777    ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
778    strcnt = shdr[symstrindex].sh_size;
779    ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
780
781    if (ef->symbase == NULL || ef->strbase == NULL) {
782	error = ENOMEM;
783	goto out;
784    }
785    error = vn_rdwr(UIO_READ, nd.ni_vp,
786		    ef->symbase, symcnt, shdr[symtabindex].sh_offset,
787		    UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
788    if (error)
789	goto out;
790    error = vn_rdwr(UIO_READ, nd.ni_vp,
791		    ef->strbase, strcnt, shdr[symstrindex].sh_offset,
792		    UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p);
793    if (error)
794	goto out;
795
796    ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
797    ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
798    ef->ddbstrcnt = strcnt;
799    ef->ddbstrtab = ef->strbase;
800
801#ifdef DDB
802    GDB_STATE(RT_ADD);
803    ef->gdb.l_addr = lf->address;
804    newfilename = malloc(strlen(filename) + 1, M_LINKER, M_WAITOK);
805    strcpy(newfilename, filename);
806    ef->gdb.l_name = (const char *)newfilename;
807    ef->gdb.l_ld = ef->dynamic;
808    link_elf_add_gdb(&ef->gdb);
809    GDB_STATE(RT_CONSISTENT);
810#endif
811
812nosyms:
813
814    *result = lf;
815
816out:
817    if (error && lf)
818	linker_file_unload(lf);
819    if (shdr)
820	free(shdr, M_LINKER);
821    if (firstpage)
822	free(firstpage, M_LINKER);
823    VOP_UNLOCK(nd.ni_vp, 0, p);
824    vn_close(nd.ni_vp, FREAD, p->p_ucred, p);
825
826    return error;
827}
828
829static void
830link_elf_unload_file(linker_file_t file)
831{
832    elf_file_t ef = (elf_file_t) file;
833
834#ifdef DDB
835    if (ef->gdb.l_ld) {
836	GDB_STATE(RT_DELETE);
837	free((void *)ef->gdb.l_name, M_LINKER);
838	link_elf_delete_gdb(&ef->gdb);
839	GDB_STATE(RT_CONSISTENT);
840    }
841#endif
842
843    if (ef->preloaded) {
844	link_elf_unload_preload(file);
845	return;
846    }
847#ifdef SPARSE_MAPPING
848    if (ef->object) {
849	vm_map_remove(kernel_map, (vm_offset_t) ef->address,
850		      (vm_offset_t) ef->address
851		      + (ef->object->size << PAGE_SHIFT));
852	vm_object_deallocate(ef->object);
853    }
854#else
855    if (ef->address)
856	free(ef->address, M_LINKER);
857#endif
858    if (ef->symbase)
859	free(ef->symbase, M_LINKER);
860    if (ef->strbase)
861	free(ef->strbase, M_LINKER);
862}
863
864static void
865link_elf_unload_preload(linker_file_t file)
866{
867    if (file->filename)
868	preload_delete_name(file->filename);
869}
870
871static const char *
872symbol_name(elf_file_t ef, Elf_Word r_info)
873{
874    const Elf_Sym *ref;
875
876    if (ELF_R_SYM(r_info)) {
877	ref = ef->symtab + ELF_R_SYM(r_info);
878	return ef->strtab + ref->st_name;
879    } else
880	return NULL;
881}
882
883static int
884relocate_file(elf_file_t ef)
885{
886    const Elf_Rel *rellim;
887    const Elf_Rel *rel;
888    const Elf_Rela *relalim;
889    const Elf_Rela *rela;
890    const char *symname;
891
892    /* Perform relocations without addend if there are any: */
893    rel = ef->rel;
894    if (rel) {
895	rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
896	while (rel < rellim) {
897	    symname = symbol_name(ef, rel->r_info);
898	    if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL, symname)) {
899		printf("link_elf: symbol %s undefined\n", symname);
900		return ENOENT;
901	    }
902	    rel++;
903	}
904    }
905
906    /* Perform relocations with addend if there are any: */
907    rela = ef->rela;
908    if (rela) {
909	relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
910	while (rela < relalim) {
911	    symname = symbol_name(ef, rela->r_info);
912	    if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA, symname)) {
913		printf("link_elf: symbol %s undefined\n", symname);
914		return ENOENT;
915	    }
916	    rela++;
917	}
918    }
919
920    /* Perform PLT relocations without addend if there are any: */
921    rel = ef->pltrel;
922    if (rel) {
923	rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
924	while (rel < rellim) {
925	    symname = symbol_name(ef, rel->r_info);
926	    if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL, symname)) {
927		printf("link_elf: symbol %s undefined\n", symname);
928		return ENOENT;
929	    }
930	    rel++;
931	}
932    }
933
934    /* Perform relocations with addend if there are any: */
935    rela = ef->pltrela;
936    if (rela) {
937	relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
938	while (rela < relalim) {
939	    symname = symbol_name(ef, rela->r_info);
940	    if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA, symname)) {
941		printf("link_elf: symbol %s undefined\n", symname);
942		return ENOENT;
943	    }
944	    rela++;
945	}
946    }
947
948    return 0;
949}
950
951/*
952 * Hash function for symbol table lookup.  Don't even think about changing
953 * this.  It is specified by the System V ABI.
954 */
955static unsigned long
956elf_hash(const char *name)
957{
958    const unsigned char *p = (const unsigned char *) name;
959    unsigned long h = 0;
960    unsigned long g;
961
962    while (*p != '\0') {
963	h = (h << 4) + *p++;
964	if ((g = h & 0xf0000000) != 0)
965	    h ^= g >> 24;
966	h &= ~g;
967    }
968    return h;
969}
970
971int
972link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
973{
974    elf_file_t ef = (elf_file_t) lf;
975    unsigned long symnum;
976    const Elf_Sym* symp;
977    const char *strp;
978    unsigned long hash;
979    int i;
980
981    /* First, search hashed global symbols */
982    hash = elf_hash(name);
983    symnum = ef->buckets[hash % ef->nbuckets];
984
985    while (symnum != STN_UNDEF) {
986	if (symnum >= ef->nchains) {
987	    printf("link_elf_lookup_symbol: corrupt symbol table\n");
988	    return ENOENT;
989	}
990
991	symp = ef->symtab + symnum;
992	if (symp->st_name == 0) {
993	    printf("link_elf_lookup_symbol: corrupt symbol table\n");
994	    return ENOENT;
995	}
996
997	strp = ef->strtab + symp->st_name;
998
999	if (strcmp(name, strp) == 0) {
1000	    if (symp->st_shndx != SHN_UNDEF ||
1001		(symp->st_value != 0 &&
1002		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1003		*sym = (c_linker_sym_t) symp;
1004		return 0;
1005	    } else
1006		return ENOENT;
1007	}
1008
1009	symnum = ef->chains[symnum];
1010    }
1011
1012    /* If we have not found it, look at the full table (if loaded) */
1013    if (ef->symtab == ef->ddbsymtab)
1014	return ENOENT;
1015
1016    /* Exhaustive search */
1017    for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1018	strp = ef->ddbstrtab + symp->st_name;
1019	if (strcmp(name, strp) == 0) {
1020	    if (symp->st_shndx != SHN_UNDEF ||
1021		(symp->st_value != 0 &&
1022		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1023		*sym = (c_linker_sym_t) symp;
1024		return 0;
1025	    } else
1026		return ENOENT;
1027	}
1028    }
1029
1030    return ENOENT;
1031}
1032
1033static int
1034link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1035{
1036	elf_file_t ef = (elf_file_t) lf;
1037	const Elf_Sym* es = (const Elf_Sym*) sym;
1038
1039	if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) {
1040	    symval->name = ef->strtab + es->st_name;
1041	    symval->value = (caddr_t) ef->address + es->st_value;
1042	    symval->size = es->st_size;
1043	    return 0;
1044	}
1045	if (ef->symtab == ef->ddbsymtab)
1046	    return ENOENT;
1047	if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) {
1048	    symval->name = ef->ddbstrtab + es->st_name;
1049	    symval->value = (caddr_t) ef->address + es->st_value;
1050	    symval->size = es->st_size;
1051	    return 0;
1052	}
1053	return ENOENT;
1054}
1055
1056static int
1057link_elf_search_symbol(linker_file_t lf, caddr_t value,
1058		       c_linker_sym_t* sym, long* diffp)
1059{
1060	elf_file_t ef = (elf_file_t) lf;
1061	u_long off = (uintptr_t) (void *) value;
1062	u_long diff = off;
1063	u_long st_value;
1064	const Elf_Sym* es;
1065	const Elf_Sym* best = 0;
1066	int i;
1067
1068	for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1069		if (es->st_name == 0)
1070			continue;
1071		st_value = es->st_value + (uintptr_t) (void *) ef->address;
1072		if (off >= st_value) {
1073			if (off - st_value < diff) {
1074				diff = off - st_value;
1075				best = es;
1076				if (diff == 0)
1077					break;
1078			} else if (off - st_value == diff) {
1079				best = es;
1080			}
1081		}
1082	}
1083	if (best == 0)
1084		*diffp = off;
1085	else
1086		*diffp = diff;
1087	*sym = (c_linker_sym_t) best;
1088
1089	return 0;
1090}
1091
1092/*
1093 * Look up a linker set on an ELF system.
1094 */
1095static int
1096link_elf_lookup_set(linker_file_t lf, const char *name,
1097		    void ***startp, void ***stopp, int *countp)
1098{
1099	c_linker_sym_t sym;
1100	linker_symval_t symval;
1101	char *setsym;
1102	void **start, **stop;
1103	int len, error = 0, count;
1104
1105	len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1106	setsym = malloc(len, M_LINKER, M_WAITOK);
1107	if (setsym == NULL)
1108		return ENOMEM;
1109
1110	/* get address of first entry */
1111	snprintf(setsym, len, "%s%s", "__start_set_", name);
1112	error = link_elf_lookup_symbol(lf, setsym, &sym);
1113	if (error)
1114		goto out;
1115	link_elf_symbol_values(lf, sym, &symval);
1116	if (symval.value == 0) {
1117		error = ESRCH;
1118		goto out;
1119	}
1120	start = (void **)symval.value;
1121
1122	/* get address of last entry */
1123	snprintf(setsym, len, "%s%s", "__stop_set_", name);
1124	error = link_elf_lookup_symbol(lf, setsym, &sym);
1125	if (error)
1126		goto out;
1127	link_elf_symbol_values(lf, sym, &symval);
1128	if (symval.value == 0) {
1129		error = ESRCH;
1130		goto out;
1131	}
1132	stop = (void **)symval.value;
1133
1134	/* and the number of entries */
1135	count = stop - start;
1136
1137	/* and copy out */
1138	if (startp)
1139		*startp = start;
1140	if (stopp)
1141		*stopp = stop;
1142	if (countp)
1143		*countp = count;
1144
1145out:
1146	free(setsym, M_LINKER);
1147	return error;
1148}
1149