link_elf.c revision 102547 
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 102547 2002-08-29 01:16:14Z jake $
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#ifdef GPROF
45#include <machine/profile.h>
46#endif
47
48#include <vm/vm.h>
49#include <vm/vm_param.h>
50#ifdef SPARSE_MAPPING
51#include <vm/vm_object.h>
52#include <vm/vm_kern.h>
53#include <vm/vm_extern.h>
54#endif
55#include <vm/pmap.h>
56#include <vm/vm_map.h>
57
58#ifdef __AOUT__
59#include <sys/nlist_aout.h>
60#endif
61#include <sys/link_elf.h>
62
63#include "linker_if.h"
64
65typedef struct elf_file {
66    struct linker_file	lf;		/* Common fields */
67    int			preloaded;	/* Was file pre-loaded */
68    caddr_t		address;	/* Relocation address */
69#ifdef SPARSE_MAPPING
70    vm_object_t		object;		/* VM object to hold file pages */
71#endif
72    Elf_Dyn*		dynamic;	/* Symbol table etc. */
73    Elf_Hashelt		nbuckets;	/* DT_HASH info */
74    Elf_Hashelt		nchains;
75    const Elf_Hashelt*	buckets;
76    const Elf_Hashelt*	chains;
77    caddr_t		hash;
78    caddr_t		strtab;		/* DT_STRTAB */
79    int			strsz;		/* DT_STRSZ */
80    const Elf_Sym*	symtab;		/* DT_SYMTAB */
81    Elf_Addr*		got;		/* DT_PLTGOT */
82    const Elf_Rel*	pltrel;		/* DT_JMPREL */
83    int			pltrelsize;	/* DT_PLTRELSZ */
84    const Elf_Rela*	pltrela;	/* DT_JMPREL */
85    int			pltrelasize;	/* DT_PLTRELSZ */
86    const Elf_Rel*	rel;		/* DT_REL */
87    int			relsize;	/* DT_RELSZ */
88    const Elf_Rela*	rela;		/* DT_RELA */
89    int			relasize;	/* DT_RELASZ */
90    caddr_t		modptr;
91    const Elf_Sym*	ddbsymtab;	/* The symbol table we are using */
92    long		ddbsymcnt;	/* Number of symbols */
93    caddr_t		ddbstrtab;	/* String table */
94    long		ddbstrcnt;	/* number of bytes in string table */
95    caddr_t		symbase;	/* malloc'ed symbold base */
96    caddr_t		strbase;	/* malloc'ed string base */
97#ifdef DDB
98    struct link_map	gdb;		/* hooks for gdb */
99#endif
100} *elf_file_t;
101
102static int	link_elf_link_preload(linker_class_t cls,
103				      const char*, linker_file_t*);
104static int	link_elf_link_preload_finish(linker_file_t);
105static int	link_elf_load_file(linker_class_t, const char*, linker_file_t*);
106static int	link_elf_lookup_symbol(linker_file_t, const char*,
107				       c_linker_sym_t*);
108static int	link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
109static int	link_elf_search_symbol(linker_file_t, caddr_t value,
110				       c_linker_sym_t* sym, long* diffp);
111
112static void	link_elf_unload_file(linker_file_t);
113static void	link_elf_unload_preload(linker_file_t);
114static int	link_elf_lookup_set(linker_file_t, const char *,
115				    void ***, void ***, int *);
116static int	link_elf_each_function_name(linker_file_t,
117				int (*)(const char *, void *),
118				void *);
119
120static kobj_method_t link_elf_methods[] = {
121    KOBJMETHOD(linker_lookup_symbol,	link_elf_lookup_symbol),
122    KOBJMETHOD(linker_symbol_values,	link_elf_symbol_values),
123    KOBJMETHOD(linker_search_symbol,	link_elf_search_symbol),
124    KOBJMETHOD(linker_unload,		link_elf_unload_file),
125    KOBJMETHOD(linker_load_file,	link_elf_load_file),
126    KOBJMETHOD(linker_link_preload,	link_elf_link_preload),
127    KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
128    KOBJMETHOD(linker_lookup_set,	link_elf_lookup_set),
129    KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
130    { 0, 0 }
131};
132
133static struct linker_class link_elf_class = {
134#if ELF_TARG_CLASS == ELFCLASS32
135    "elf32",
136#else
137    "elf64",
138#endif
139    link_elf_methods, sizeof(struct elf_file)
140};
141
142static int		parse_dynamic(elf_file_t ef);
143static int		relocate_file(elf_file_t ef);
144static int		link_elf_preload_parse_symbols(elf_file_t ef);
145
146#ifdef DDB
147static void		r_debug_state(struct r_debug *dummy_one,
148				      struct link_map *dummy_two);
149
150/*
151 * A list of loaded modules for GDB to use for loading symbols.
152 */
153struct r_debug r_debug;
154
155#define GDB_STATE(s)	r_debug.r_state = s; r_debug_state(NULL, NULL);
156
157/*
158 * Function for the debugger to set a breakpoint on to gain control.
159 */
160void
161r_debug_state(struct r_debug *dummy_one __unused,
162	      struct link_map *dummy_two __unused)
163{
164}
165
166#endif
167
168#ifdef __ia64__
169Elf_Addr link_elf_get_gp(linker_file_t);
170#endif
171
172/*
173 * The kernel symbol table starts here.
174 */
175extern struct _dynamic _DYNAMIC;
176
177static void
178link_elf_init(void* arg)
179{
180#ifdef __ELF__
181    Elf_Dyn	*dp;
182    caddr_t	modptr, baseptr, sizeptr;
183    elf_file_t	ef;
184    char	*modname;
185#ifdef DDB
186    char *newfilename;
187#endif
188#endif
189
190    linker_add_class(&link_elf_class);
191
192#ifdef __ELF__
193    dp = (Elf_Dyn*) &_DYNAMIC;
194    modname = NULL;
195    modptr = preload_search_by_type("elf kernel");
196    if (modptr)
197	modname = (char *)preload_search_info(modptr, MODINFO_NAME);
198    if (modname == NULL)
199	modname = "kernel";
200    linker_kernel_file = linker_make_file(modname, &link_elf_class);
201    if (linker_kernel_file == NULL)
202	panic("link_elf_init: Can't create linker structures for kernel");
203
204    ef = (elf_file_t) linker_kernel_file;
205    ef->preloaded = 1;
206    ef->address = 0;
207#ifdef SPARSE_MAPPING
208    ef->object = 0;
209#endif
210    ef->dynamic = dp;
211
212    if (dp)
213	parse_dynamic(ef);
214    linker_kernel_file->address = (caddr_t) KERNBASE;
215    linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
216
217    if (modptr) {
218	ef->modptr = modptr;
219	baseptr = preload_search_info(modptr, MODINFO_ADDR);
220	if (baseptr)
221	    linker_kernel_file->address = *(caddr_t *)baseptr;
222	sizeptr = preload_search_info(modptr, MODINFO_SIZE);
223	if (sizeptr)
224	    linker_kernel_file->size = *(size_t *)sizeptr;
225    }
226    (void)link_elf_preload_parse_symbols(ef);
227
228#ifdef DDB
229    ef->gdb.l_addr = linker_kernel_file->address;
230    newfilename = malloc(strlen(modname) + 1, M_LINKER, M_WAITOK);
231    strcpy(newfilename, modname);
232    ef->gdb.l_name = newfilename;
233    ef->gdb.l_ld = dp;
234    ef->gdb.l_prev = 0;
235    ef->gdb.l_next = 0;
236
237    r_debug.r_map = &ef->gdb;
238    r_debug.r_brk = r_debug_state;
239    r_debug.r_state = RT_CONSISTENT;
240
241    r_debug_state(NULL, NULL);	/* say hello to gdb! */
242#endif
243
244#endif
245}
246
247SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
248
249static int
250link_elf_preload_parse_symbols(elf_file_t ef)
251{
252    caddr_t	pointer;
253    caddr_t	ssym, esym, base;
254    caddr_t	strtab;
255    int		strcnt;
256    Elf_Sym*	symtab;
257    int		symcnt;
258
259    if (ef->modptr == NULL)
260	return 0;
261    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
262    if (pointer == NULL)
263	return 0;
264    ssym = *(caddr_t *)pointer;
265    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
266    if (pointer == NULL)
267	return 0;
268    esym = *(caddr_t *)pointer;
269
270    base = ssym;
271
272    symcnt = *(long *)base;
273    base += sizeof(long);
274    symtab = (Elf_Sym *)base;
275    base += roundup(symcnt, sizeof(long));
276
277    if (base > esym || base < ssym) {
278	printf("Symbols are corrupt!\n");
279	return EINVAL;
280    }
281
282    strcnt = *(long *)base;
283    base += sizeof(long);
284    strtab = base;
285    base += roundup(strcnt, sizeof(long));
286
287    if (base > esym || base < ssym) {
288	printf("Symbols are corrupt!\n");
289	return EINVAL;
290    }
291
292    ef->ddbsymtab = symtab;
293    ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
294    ef->ddbstrtab = strtab;
295    ef->ddbstrcnt = strcnt;
296
297    return 0;
298}
299
300static int
301parse_dynamic(elf_file_t ef)
302{
303    Elf_Dyn *dp;
304    int plttype = DT_REL;
305
306    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
307	switch (dp->d_tag) {
308	case DT_HASH:
309	{
310	    /* From src/libexec/rtld-elf/rtld.c */
311	    const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
312		(ef->address + dp->d_un.d_ptr);
313	    ef->nbuckets = hashtab[0];
314	    ef->nchains = hashtab[1];
315	    ef->buckets = hashtab + 2;
316	    ef->chains = ef->buckets + ef->nbuckets;
317	    break;
318	}
319	case DT_STRTAB:
320	    ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
321	    break;
322	case DT_STRSZ:
323	    ef->strsz = dp->d_un.d_val;
324	    break;
325	case DT_SYMTAB:
326	    ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
327	    break;
328	case DT_SYMENT:
329	    if (dp->d_un.d_val != sizeof(Elf_Sym))
330		return ENOEXEC;
331	    break;
332	case DT_PLTGOT:
333	    ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
334	    break;
335	case DT_REL:
336	    ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
337	    break;
338	case DT_RELSZ:
339	    ef->relsize = dp->d_un.d_val;
340	    break;
341	case DT_RELENT:
342	    if (dp->d_un.d_val != sizeof(Elf_Rel))
343		return ENOEXEC;
344	    break;
345	case DT_JMPREL:
346	    ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
347	    break;
348	case DT_PLTRELSZ:
349	    ef->pltrelsize = dp->d_un.d_val;
350	    break;
351	case DT_RELA:
352	    ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
353	    break;
354	case DT_RELASZ:
355	    ef->relasize = dp->d_un.d_val;
356	    break;
357	case DT_RELAENT:
358	    if (dp->d_un.d_val != sizeof(Elf_Rela))
359		return ENOEXEC;
360	    break;
361	case DT_PLTREL:
362	    plttype = dp->d_un.d_val;
363	    if (plttype != DT_REL && plttype != DT_RELA)
364		return ENOEXEC;
365	    break;
366#ifdef DDB
367	case DT_DEBUG:
368	    dp->d_un.d_ptr = (Elf_Addr) &r_debug;
369	    break;
370#endif
371	}
372    }
373
374    if (plttype == DT_RELA) {
375	ef->pltrela = (const Elf_Rela *) ef->pltrel;
376	ef->pltrel = NULL;
377	ef->pltrelasize = ef->pltrelsize;
378	ef->pltrelsize = 0;
379    }
380
381    ef->ddbsymtab = ef->symtab;
382    ef->ddbsymcnt = ef->nchains;
383    ef->ddbstrtab = ef->strtab;
384    ef->ddbstrcnt = ef->strsz;
385
386    return 0;
387}
388
389static void
390link_elf_error(const char *s)
391{
392    printf("kldload: %s\n", s);
393}
394
395#ifdef DDB
396
397static void
398link_elf_add_gdb(struct link_map *l)
399{
400    struct link_map *prev;
401
402    /*
403     * Scan to the end of the list.
404     */
405    for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
406	;
407
408    /* Link in the new entry. */
409    l->l_prev = prev;
410    l->l_next = prev->l_next;
411    prev->l_next = l;
412}
413
414static void
415link_elf_delete_gdb(struct link_map *l)
416{
417    if (l->l_prev == NULL) {
418	if ((r_debug.r_map = l->l_next) != NULL)
419	    l->l_next->l_prev = NULL;
420	return;
421    }
422
423    if ((l->l_prev->l_next = l->l_next) != NULL)
424	l->l_next->l_prev = l->l_prev;
425}
426
427#endif /* DDB */
428
429static int
430link_elf_link_preload(linker_class_t cls,
431		      const char* filename, linker_file_t *result)
432{
433    caddr_t		modptr, baseptr, sizeptr, dynptr;
434    char		*type;
435    elf_file_t		ef;
436    linker_file_t	lf;
437    int			error;
438    vm_offset_t		dp;
439
440    /* Look to see if we have the file preloaded */
441    modptr = preload_search_by_name(filename);
442    if (modptr == NULL)
443	return ENOENT;
444
445    type = (char *)preload_search_info(modptr, MODINFO_TYPE);
446    baseptr = preload_search_info(modptr, MODINFO_ADDR);
447    sizeptr = preload_search_info(modptr, MODINFO_SIZE);
448    dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
449    if (type == NULL || strcmp(type, "elf module") != 0)
450	return (EFTYPE);
451    if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
452	return (EINVAL);
453
454    lf = linker_make_file(filename, &link_elf_class);
455    if (lf == NULL) {
456	return ENOMEM;
457    }
458
459    ef = (elf_file_t) lf;
460    ef->preloaded = 1;
461    ef->modptr = modptr;
462    ef->address = *(caddr_t *)baseptr;
463#ifdef SPARSE_MAPPING
464    ef->object = 0;
465#endif
466    dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
467    ef->dynamic = (Elf_Dyn *)dp;
468    lf->address = ef->address;
469    lf->size = *(size_t *)sizeptr;
470
471    error = parse_dynamic(ef);
472    if (error) {
473	linker_file_unload(lf);
474	return error;
475    }
476    *result = lf;
477    return (0);
478}
479
480static int
481link_elf_link_preload_finish(linker_file_t lf)
482{
483    elf_file_t		ef;
484    int error;
485#ifdef DDB
486    char *newfilename;
487#endif
488
489    ef = (elf_file_t) lf;
490#if 0	/* this will be more trouble than it's worth for now */
491    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
492	if (dp->d_tag != DT_NEEDED)
493	    continue;
494	modname = ef->strtab + dp->d_un.d_val;
495	error = linker_load_module(modname, lf);
496	if (error)
497	    goto out;
498    }
499#endif
500    error = relocate_file(ef);
501    if (error)
502	return error;
503    (void)link_elf_preload_parse_symbols(ef);
504
505#ifdef DDB
506    GDB_STATE(RT_ADD);
507    ef->gdb.l_addr = lf->address;
508    newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
509    strcpy(newfilename, lf->filename);
510    ef->gdb.l_name = newfilename;
511    ef->gdb.l_ld = ef->dynamic;
512    link_elf_add_gdb(&ef->gdb);
513    GDB_STATE(RT_CONSISTENT);
514#endif
515
516    return (0);
517}
518
519static int
520link_elf_load_file(linker_class_t cls, const char* filename, linker_file_t* result)
521{
522    struct nameidata nd;
523    struct thread* td = curthread;	/* XXX */
524    Elf_Ehdr *hdr;
525    caddr_t firstpage;
526    int nbytes, i;
527    Elf_Phdr *phdr;
528    Elf_Phdr *phlimit;
529    Elf_Phdr *segs[2];
530    int nsegs;
531    Elf_Phdr *phdyn;
532    Elf_Phdr *phphdr;
533    caddr_t mapbase;
534    size_t mapsize;
535    Elf_Off base_offset;
536    Elf_Addr base_vaddr;
537    Elf_Addr base_vlimit;
538    int error = 0;
539    int resid, flags;
540    elf_file_t ef;
541    linker_file_t lf;
542    Elf_Shdr *shdr;
543    int symtabindex;
544    int symstrindex;
545    int symcnt;
546    int strcnt;
547#ifdef DDB
548    char *newfilename;
549#endif
550
551    GIANT_REQUIRED;
552
553    shdr = NULL;
554    lf = NULL;
555
556    NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
557    flags = FREAD;
558    error = vn_open(&nd, &flags, 0);
559    if (error)
560	return error;
561    NDFREE(&nd, NDF_ONLY_PNBUF);
562
563    /*
564     * Read the elf header from the file.
565     */
566    firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
567    if (firstpage == NULL) {
568	error = ENOMEM;
569	goto out;
570    }
571    hdr = (Elf_Ehdr *)firstpage;
572    error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
573		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
574		    &resid, td);
575    nbytes = PAGE_SIZE - resid;
576    if (error)
577	goto out;
578
579    if (!IS_ELF(*hdr)) {
580	error = ENOEXEC;
581	goto out;
582    }
583
584    if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
585      || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
586	link_elf_error("Unsupported file layout");
587	error = ENOEXEC;
588	goto out;
589    }
590    if (hdr->e_ident[EI_VERSION] != EV_CURRENT
591      || hdr->e_version != EV_CURRENT) {
592	link_elf_error("Unsupported file version");
593	error = ENOEXEC;
594	goto out;
595    }
596    if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
597	link_elf_error("Unsupported file type");
598	error = ENOEXEC;
599	goto out;
600    }
601    if (hdr->e_machine != ELF_TARG_MACH) {
602	link_elf_error("Unsupported machine");
603	error = ENOEXEC;
604	goto out;
605    }
606
607    /*
608     * We rely on the program header being in the first page.  This is
609     * not strictly required by the ABI specification, but it seems to
610     * always true in practice.  And, it simplifies things considerably.
611     */
612    if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
613	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
614	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
615	link_elf_error("Unreadable program headers");
616
617    /*
618     * Scan the program header entries, and save key information.
619     *
620     * We rely on there being exactly two load segments, text and data,
621     * in that order.
622     */
623    phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
624    phlimit = phdr + hdr->e_phnum;
625    nsegs = 0;
626    phdyn = NULL;
627    phphdr = NULL;
628    while (phdr < phlimit) {
629	switch (phdr->p_type) {
630
631	case PT_LOAD:
632	    if (nsegs == 2) {
633		link_elf_error("Too many sections");
634		error = ENOEXEC;
635		goto out;
636	    }
637	    segs[nsegs] = phdr;
638	    ++nsegs;
639	    break;
640
641	case PT_PHDR:
642	    phphdr = phdr;
643	    break;
644
645	case PT_DYNAMIC:
646	    phdyn = phdr;
647	    break;
648
649	case PT_INTERP:
650	    link_elf_error("Unsupported file type");
651	    error = ENOEXEC;
652	    goto out;
653	}
654
655	++phdr;
656    }
657    if (phdyn == NULL) {
658	link_elf_error("Object is not dynamically-linked");
659	error = ENOEXEC;
660	goto out;
661    }
662
663    /*
664     * Allocate the entire address space of the object, to stake out our
665     * contiguous region, and to establish the base address for relocation.
666     */
667    base_offset = trunc_page(segs[0]->p_offset);
668    base_vaddr = trunc_page(segs[0]->p_vaddr);
669    base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
670    mapsize = base_vlimit - base_vaddr;
671
672    lf = linker_make_file(filename, &link_elf_class);
673    if (!lf) {
674	error = ENOMEM;
675	goto out;
676    }
677
678    ef = (elf_file_t) lf;
679#ifdef SPARSE_MAPPING
680    ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
681    if (ef->object == NULL) {
682	free(ef, M_LINKER);
683	error = ENOMEM;
684	goto out;
685    }
686    vm_object_reference(ef->object);
687    ef->address = (caddr_t) vm_map_min(kernel_map);
688    error = vm_map_find(kernel_map, ef->object, 0,
689			(vm_offset_t *) &ef->address,
690			mapsize, 1,
691			VM_PROT_ALL, VM_PROT_ALL, 0);
692    if (error) {
693	vm_object_deallocate(ef->object);
694	ef->object = 0;
695	goto out;
696    }
697#else
698    ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
699    if (!ef->address) {
700	error = ENOMEM;
701	goto out;
702    }
703#endif
704    mapbase = ef->address;
705
706    /*
707     * Read the text and data sections and zero the bss.
708     */
709    for (i = 0; i < 2; i++) {
710	caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
711	error = vn_rdwr(UIO_READ, nd.ni_vp,
712			segbase, segs[i]->p_filesz, segs[i]->p_offset,
713			UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
714			&resid, td);
715	if (error) {
716	    goto out;
717	}
718	bzero(segbase + segs[i]->p_filesz,
719	      segs[i]->p_memsz - segs[i]->p_filesz);
720
721#ifdef SPARSE_MAPPING
722	/*
723	 * Wire down the pages
724	 */
725	vm_map_wire(kernel_map,
726		    (vm_offset_t) segbase,
727		    (vm_offset_t) segbase + segs[i]->p_memsz,
728		    FALSE);
729#endif
730    }
731
732#ifdef GPROF
733    /* Update profiling information with the new text segment. */
734    kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
735	segs[0]->p_memsz));
736#endif
737
738    ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
739
740    lf->address = ef->address;
741    lf->size = mapsize;
742
743    error = parse_dynamic(ef);
744    if (error)
745	goto out;
746    error = linker_load_dependencies(lf);
747    if (error)
748	goto out;
749#if 0	/* this will be more trouble than it's worth for now */
750    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
751	if (dp->d_tag != DT_NEEDED)
752	    continue;
753	modname = ef->strtab + dp->d_un.d_val;
754	error = linker_load_module(modname, lf);
755	if (error)
756	    goto out;
757    }
758#endif
759    error = relocate_file(ef);
760    if (error)
761	goto out;
762
763    /* Try and load the symbol table if it's present.  (you can strip it!) */
764    nbytes = hdr->e_shnum * hdr->e_shentsize;
765    if (nbytes == 0 || hdr->e_shoff == 0)
766	goto nosyms;
767    shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
768    if (shdr == NULL) {
769	error = ENOMEM;
770	goto out;
771    }
772    error = vn_rdwr(UIO_READ, nd.ni_vp,
773		    (caddr_t)shdr, nbytes, hdr->e_shoff,
774		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
775		    &resid, td);
776    if (error)
777	goto out;
778    symtabindex = -1;
779    symstrindex = -1;
780    for (i = 0; i < hdr->e_shnum; i++) {
781	if (shdr[i].sh_type == SHT_SYMTAB) {
782	    symtabindex = i;
783	    symstrindex = shdr[i].sh_link;
784	}
785    }
786    if (symtabindex < 0 || symstrindex < 0)
787	goto nosyms;
788
789    symcnt = shdr[symtabindex].sh_size;
790    ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
791    strcnt = shdr[symstrindex].sh_size;
792    ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
793
794    if (ef->symbase == NULL || ef->strbase == NULL) {
795	error = ENOMEM;
796	goto out;
797    }
798    error = vn_rdwr(UIO_READ, nd.ni_vp,
799		    ef->symbase, symcnt, shdr[symtabindex].sh_offset,
800		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
801		    &resid, td);
802    if (error)
803	goto out;
804    error = vn_rdwr(UIO_READ, nd.ni_vp,
805		    ef->strbase, strcnt, shdr[symstrindex].sh_offset,
806		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
807		    &resid, td);
808    if (error)
809	goto out;
810
811    ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
812    ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
813    ef->ddbstrcnt = strcnt;
814    ef->ddbstrtab = ef->strbase;
815
816#ifdef DDB
817    GDB_STATE(RT_ADD);
818    ef->gdb.l_addr = lf->address;
819    newfilename = malloc(strlen(filename) + 1, M_LINKER, M_WAITOK);
820    strcpy(newfilename, filename);
821    ef->gdb.l_name = (const char *)newfilename;
822    ef->gdb.l_ld = ef->dynamic;
823    link_elf_add_gdb(&ef->gdb);
824    GDB_STATE(RT_CONSISTENT);
825#endif
826
827nosyms:
828
829    *result = lf;
830
831out:
832    if (error && lf)
833	linker_file_unload(lf);
834    if (shdr)
835	free(shdr, M_LINKER);
836    if (firstpage)
837	free(firstpage, M_LINKER);
838    VOP_UNLOCK(nd.ni_vp, 0, td);
839    vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
840
841    return error;
842}
843
844static void
845link_elf_unload_file(linker_file_t file)
846{
847    elf_file_t ef = (elf_file_t) file;
848
849#ifdef DDB
850    if (ef->gdb.l_ld) {
851	GDB_STATE(RT_DELETE);
852	free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
853	link_elf_delete_gdb(&ef->gdb);
854	GDB_STATE(RT_CONSISTENT);
855    }
856#endif
857
858    if (ef->preloaded) {
859	link_elf_unload_preload(file);
860	return;
861    }
862#ifdef SPARSE_MAPPING
863    if (ef->object) {
864	vm_map_remove(kernel_map, (vm_offset_t) ef->address,
865		      (vm_offset_t) ef->address
866		      + (ef->object->size << PAGE_SHIFT));
867	vm_object_deallocate(ef->object);
868    }
869#else
870    if (ef->address)
871	free(ef->address, M_LINKER);
872#endif
873    if (ef->symbase)
874	free(ef->symbase, M_LINKER);
875    if (ef->strbase)
876	free(ef->strbase, M_LINKER);
877}
878
879static void
880link_elf_unload_preload(linker_file_t file)
881{
882    if (file->filename)
883	preload_delete_name(file->filename);
884}
885
886static const char *
887symbol_name(elf_file_t ef, Elf_Word r_info)
888{
889    const Elf_Sym *ref;
890
891    if (ELF_R_SYM(r_info)) {
892	ref = ef->symtab + ELF_R_SYM(r_info);
893	return ef->strtab + ref->st_name;
894    } else
895	return NULL;
896}
897
898static int
899relocate_file(elf_file_t ef)
900{
901    const Elf_Rel *rellim;
902    const Elf_Rel *rel;
903    const Elf_Rela *relalim;
904    const Elf_Rela *rela;
905    const char *symname;
906
907    /* Perform relocations without addend if there are any: */
908    rel = ef->rel;
909    if (rel) {
910	rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
911	while (rel < rellim) {
912	    if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) {
913		symname = symbol_name(ef, rel->r_info);
914		printf("link_elf: symbol %s undefined\n", symname);
915		return ENOENT;
916	    }
917	    rel++;
918	}
919    }
920
921    /* Perform relocations with addend if there are any: */
922    rela = ef->rela;
923    if (rela) {
924	relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
925	while (rela < relalim) {
926	    if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) {
927		symname = symbol_name(ef, rela->r_info);
928		printf("link_elf: symbol %s undefined\n", symname);
929		return ENOENT;
930	    }
931	    rela++;
932	}
933    }
934
935    /* Perform PLT relocations without addend if there are any: */
936    rel = ef->pltrel;
937    if (rel) {
938	rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
939	while (rel < rellim) {
940	    if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) {
941		symname = symbol_name(ef, rel->r_info);
942		printf("link_elf: symbol %s undefined\n", symname);
943		return ENOENT;
944	    }
945	    rel++;
946	}
947    }
948
949    /* Perform relocations with addend if there are any: */
950    rela = ef->pltrela;
951    if (rela) {
952	relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
953	while (rela < relalim) {
954	    if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) {
955		symname = symbol_name(ef, rela->r_info);
956		printf("link_elf: symbol %s undefined\n", symname);
957		return ENOENT;
958	    }
959	    rela++;
960	}
961    }
962
963    return 0;
964}
965
966/*
967 * Hash function for symbol table lookup.  Don't even think about changing
968 * this.  It is specified by the System V ABI.
969 */
970static unsigned long
971elf_hash(const char *name)
972{
973    const unsigned char *p = (const unsigned char *) name;
974    unsigned long h = 0;
975    unsigned long g;
976
977    while (*p != '\0') {
978	h = (h << 4) + *p++;
979	if ((g = h & 0xf0000000) != 0)
980	    h ^= g >> 24;
981	h &= ~g;
982    }
983    return h;
984}
985
986int
987link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
988{
989    elf_file_t ef = (elf_file_t) lf;
990    unsigned long symnum;
991    const Elf_Sym* symp;
992    const char *strp;
993    unsigned long hash;
994    int i;
995
996    /* First, search hashed global symbols */
997    hash = elf_hash(name);
998    symnum = ef->buckets[hash % ef->nbuckets];
999
1000    while (symnum != STN_UNDEF) {
1001	if (symnum >= ef->nchains) {
1002	    printf("link_elf_lookup_symbol: corrupt symbol table\n");
1003	    return ENOENT;
1004	}
1005
1006	symp = ef->symtab + symnum;
1007	if (symp->st_name == 0) {
1008	    printf("link_elf_lookup_symbol: corrupt symbol table\n");
1009	    return ENOENT;
1010	}
1011
1012	strp = ef->strtab + symp->st_name;
1013
1014	if (strcmp(name, strp) == 0) {
1015	    if (symp->st_shndx != SHN_UNDEF ||
1016		(symp->st_value != 0 &&
1017		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1018		*sym = (c_linker_sym_t) symp;
1019		return 0;
1020	    } else
1021		return ENOENT;
1022	}
1023
1024	symnum = ef->chains[symnum];
1025    }
1026
1027    /* If we have not found it, look at the full table (if loaded) */
1028    if (ef->symtab == ef->ddbsymtab)
1029	return ENOENT;
1030
1031    /* Exhaustive search */
1032    for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1033	strp = ef->ddbstrtab + symp->st_name;
1034	if (strcmp(name, strp) == 0) {
1035	    if (symp->st_shndx != SHN_UNDEF ||
1036		(symp->st_value != 0 &&
1037		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1038		*sym = (c_linker_sym_t) symp;
1039		return 0;
1040	    } else
1041		return ENOENT;
1042	}
1043    }
1044
1045    return ENOENT;
1046}
1047
1048static int
1049link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1050{
1051	elf_file_t ef = (elf_file_t) lf;
1052	const Elf_Sym* es = (const Elf_Sym*) sym;
1053
1054	if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1055	    symval->name = ef->strtab + es->st_name;
1056	    symval->value = (caddr_t) ef->address + es->st_value;
1057	    symval->size = es->st_size;
1058	    return 0;
1059	}
1060	if (ef->symtab == ef->ddbsymtab)
1061	    return ENOENT;
1062	if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1063	    symval->name = ef->ddbstrtab + es->st_name;
1064	    symval->value = (caddr_t) ef->address + es->st_value;
1065	    symval->size = es->st_size;
1066	    return 0;
1067	}
1068	return ENOENT;
1069}
1070
1071static int
1072link_elf_search_symbol(linker_file_t lf, caddr_t value,
1073		       c_linker_sym_t* sym, long* diffp)
1074{
1075	elf_file_t ef = (elf_file_t) lf;
1076	u_long off = (uintptr_t) (void *) value;
1077	u_long diff = off;
1078	u_long st_value;
1079	const Elf_Sym* es;
1080	const Elf_Sym* best = 0;
1081	int i;
1082
1083	for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1084		if (es->st_name == 0)
1085			continue;
1086		st_value = es->st_value + (uintptr_t) (void *) ef->address;
1087		if (off >= st_value) {
1088			if (off - st_value < diff) {
1089				diff = off - st_value;
1090				best = es;
1091				if (diff == 0)
1092					break;
1093			} else if (off - st_value == diff) {
1094				best = es;
1095			}
1096		}
1097	}
1098	if (best == 0)
1099		*diffp = off;
1100	else
1101		*diffp = diff;
1102	*sym = (c_linker_sym_t) best;
1103
1104	return 0;
1105}
1106
1107/*
1108 * Look up a linker set on an ELF system.
1109 */
1110static int
1111link_elf_lookup_set(linker_file_t lf, const char *name,
1112		    void ***startp, void ***stopp, int *countp)
1113{
1114	c_linker_sym_t sym;
1115	linker_symval_t symval;
1116	char *setsym;
1117	void **start, **stop;
1118	int len, error = 0, count;
1119
1120	len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1121	setsym = malloc(len, M_LINKER, M_WAITOK);
1122	if (setsym == NULL)
1123		return ENOMEM;
1124
1125	/* get address of first entry */
1126	snprintf(setsym, len, "%s%s", "__start_set_", name);
1127	error = link_elf_lookup_symbol(lf, setsym, &sym);
1128	if (error)
1129		goto out;
1130	link_elf_symbol_values(lf, sym, &symval);
1131	if (symval.value == 0) {
1132		error = ESRCH;
1133		goto out;
1134	}
1135	start = (void **)symval.value;
1136
1137	/* get address of last entry */
1138	snprintf(setsym, len, "%s%s", "__stop_set_", name);
1139	error = link_elf_lookup_symbol(lf, setsym, &sym);
1140	if (error)
1141		goto out;
1142	link_elf_symbol_values(lf, sym, &symval);
1143	if (symval.value == 0) {
1144		error = ESRCH;
1145		goto out;
1146	}
1147	stop = (void **)symval.value;
1148
1149	/* and the number of entries */
1150	count = stop - start;
1151
1152	/* and copy out */
1153	if (startp)
1154		*startp = start;
1155	if (stopp)
1156		*stopp = stop;
1157	if (countp)
1158		*countp = count;
1159
1160out:
1161	free(setsym, M_LINKER);
1162	return error;
1163}
1164
1165static int
1166link_elf_each_function_name(linker_file_t file,
1167  int (*callback)(const char *, void *), void *opaque) {
1168    elf_file_t ef = (elf_file_t)file;
1169    const Elf_Sym* symp;
1170    int i, error;
1171
1172    /* Exhaustive search */
1173    for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1174	if (symp->st_value != 0 &&
1175	    ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1176		error = callback(ef->ddbstrtab + symp->st_name, opaque);
1177		if (error)
1178		    return (error);
1179	}
1180    }
1181    return (0);
1182}
1183
1184#ifdef __ia64__
1185/*
1186 * Each KLD has its own GP. The GP value for each load module is given by
1187 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
1188 * don't have direct access to the ELF file structure. The link_elf_get_gp()
1189 * function returns the GP given a pointer to a generic linker file struct.
1190 */
1191Elf_Addr
1192link_elf_get_gp(linker_file_t lf)
1193{
1194	elf_file_t ef = (elf_file_t)lf;
1195	return (Elf_Addr)ef->got;
1196}
1197#endif
1198
1199/*
1200 * Symbol lookup function that can be used when the symbol index is known (ie
1201 * in relocations). It uses the symbol index instead of doing a fully fledged
1202 * hash table based lookup when such is valid. For example for local symbols.
1203 * This is not only more efficient, it's also more correct. It's not always
1204 * the case that the symbol can be found through the hash table.
1205 */
1206Elf_Addr
1207elf_lookup(linker_file_t lf, Elf_Word symidx, int deps)
1208{
1209	elf_file_t ef = (elf_file_t)lf;
1210	const Elf_Sym *sym;
1211	const char *symbol;
1212
1213	/* Don't even try to lookup the symbol if the index is bogus. */
1214	if (symidx >= ef->nchains)
1215		return (0);
1216
1217	sym = ef->symtab + symidx;
1218
1219	/*
1220	 * Don't do a full lookup when the symbol is local. It may even
1221	 * fail because it may not be found through the hash table.
1222	 */
1223	if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1224		/* Force lookup failure when we have an insanity. */
1225		if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1226			return (0);
1227		return ((Elf_Addr)ef->address + sym->st_value);
1228	}
1229
1230	/*
1231	 * XXX we can avoid doing a hash table based lookup for global
1232	 * symbols as well. This however is not always valid, so we'll
1233	 * just do it the hard way for now. Performance tweaks can
1234	 * always be added.
1235	 */
1236
1237	symbol = ef->strtab + sym->st_name;
1238
1239	/* Force a lookup failure if the symbol name is bogus. */
1240	if (*symbol == 0)
1241		return (0);
1242
1243	return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1244}
1245