link_elf.c revision 163606 
1/*-
2 * Copyright (c) 1998-2000 Doug Rabson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/kern/link_elf.c 163606 2006-10-22 11:52:19Z rwatson $");
29
30#include "opt_gdb.h"
31#include "opt_mac.h"
32
33#include <sys/param.h>
34#include <sys/systm.h>
35#ifdef GPROF
36#include <sys/gmon.h>
37#endif
38#include <sys/kernel.h>
39#include <sys/lock.h>
40#include <sys/malloc.h>
41#include <sys/mutex.h>
42#include <sys/mount.h>
43#include <sys/proc.h>
44#include <sys/namei.h>
45#include <sys/fcntl.h>
46#include <sys/vnode.h>
47#include <sys/linker.h>
48
49#include <machine/elf.h>
50
51#include <security/mac/mac_framework.h>
52
53#include <vm/vm.h>
54#include <vm/vm_param.h>
55#ifdef SPARSE_MAPPING
56#include <vm/vm_object.h>
57#include <vm/vm_kern.h>
58#include <vm/vm_extern.h>
59#endif
60#include <vm/pmap.h>
61#include <vm/vm_map.h>
62
63#include <sys/link_elf.h>
64
65#include "linker_if.h"
66
67#define MAXSEGS 4
68
69typedef struct elf_file {
70    struct linker_file	lf;		/* Common fields */
71    int			preloaded;	/* Was file pre-loaded */
72    caddr_t		address;	/* Relocation address */
73#ifdef SPARSE_MAPPING
74    vm_object_t		object;		/* VM object to hold file pages */
75#endif
76    Elf_Dyn*		dynamic;	/* Symbol table etc. */
77    Elf_Hashelt		nbuckets;	/* DT_HASH info */
78    Elf_Hashelt		nchains;
79    const Elf_Hashelt*	buckets;
80    const Elf_Hashelt*	chains;
81    caddr_t		hash;
82    caddr_t		strtab;		/* DT_STRTAB */
83    int			strsz;		/* DT_STRSZ */
84    const Elf_Sym*	symtab;		/* DT_SYMTAB */
85    Elf_Addr*		got;		/* DT_PLTGOT */
86    const Elf_Rel*	pltrel;		/* DT_JMPREL */
87    int			pltrelsize;	/* DT_PLTRELSZ */
88    const Elf_Rela*	pltrela;	/* DT_JMPREL */
89    int			pltrelasize;	/* DT_PLTRELSZ */
90    const Elf_Rel*	rel;		/* DT_REL */
91    int			relsize;	/* DT_RELSZ */
92    const Elf_Rela*	rela;		/* DT_RELA */
93    int			relasize;	/* DT_RELASZ */
94    caddr_t		modptr;
95    const Elf_Sym*	ddbsymtab;	/* The symbol table we are using */
96    long		ddbsymcnt;	/* Number of symbols */
97    caddr_t		ddbstrtab;	/* String table */
98    long		ddbstrcnt;	/* number of bytes in string table */
99    caddr_t		symbase;	/* malloc'ed symbold base */
100    caddr_t		strbase;	/* malloc'ed string base */
101#ifdef GDB
102    struct link_map	gdb;		/* hooks for gdb */
103#endif
104} *elf_file_t;
105
106static int	link_elf_link_common_finish(linker_file_t);
107static int	link_elf_link_preload(linker_class_t cls,
108				      const char*, linker_file_t*);
109static int	link_elf_link_preload_finish(linker_file_t);
110static int	link_elf_load_file(linker_class_t, const char*, linker_file_t*);
111static int	link_elf_lookup_symbol(linker_file_t, const char*,
112				       c_linker_sym_t*);
113static int	link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*);
114static int	link_elf_search_symbol(linker_file_t, caddr_t value,
115				       c_linker_sym_t* sym, long* diffp);
116
117static void	link_elf_unload_file(linker_file_t);
118static void	link_elf_unload_preload(linker_file_t);
119static int	link_elf_lookup_set(linker_file_t, const char *,
120				    void ***, void ***, int *);
121static int	link_elf_each_function_name(linker_file_t,
122				int (*)(const char *, void *),
123				void *);
124static void	link_elf_reloc_local(linker_file_t);
125static Elf_Addr	elf_lookup(linker_file_t lf, Elf_Size symidx, int deps);
126
127static kobj_method_t link_elf_methods[] = {
128    KOBJMETHOD(linker_lookup_symbol,	link_elf_lookup_symbol),
129    KOBJMETHOD(linker_symbol_values,	link_elf_symbol_values),
130    KOBJMETHOD(linker_search_symbol,	link_elf_search_symbol),
131    KOBJMETHOD(linker_unload,		link_elf_unload_file),
132    KOBJMETHOD(linker_load_file,	link_elf_load_file),
133    KOBJMETHOD(linker_link_preload,	link_elf_link_preload),
134    KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
135    KOBJMETHOD(linker_lookup_set,	link_elf_lookup_set),
136    KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
137    { 0, 0 }
138};
139
140static struct linker_class link_elf_class = {
141#if ELF_TARG_CLASS == ELFCLASS32
142    "elf32",
143#else
144    "elf64",
145#endif
146    link_elf_methods, sizeof(struct elf_file)
147};
148
149static int		parse_dynamic(elf_file_t ef);
150static int		relocate_file(elf_file_t ef);
151static int		link_elf_preload_parse_symbols(elf_file_t ef);
152
153#ifdef GDB
154static void		r_debug_state(struct r_debug *dummy_one,
155				      struct link_map *dummy_two);
156
157/*
158 * A list of loaded modules for GDB to use for loading symbols.
159 */
160struct r_debug r_debug;
161
162#define GDB_STATE(s)	r_debug.r_state = s; r_debug_state(NULL, NULL);
163
164/*
165 * Function for the debugger to set a breakpoint on to gain control.
166 */
167static void
168r_debug_state(struct r_debug *dummy_one __unused,
169	      struct link_map *dummy_two __unused)
170{
171}
172
173static void
174link_elf_add_gdb(struct link_map *l)
175{
176    struct link_map *prev;
177
178    l->l_next = NULL;
179
180    if (r_debug.r_map == NULL) {
181	/* Add first. */
182	l->l_prev = NULL;
183	r_debug.r_map = l;
184    } else {
185	/* Append to list. */
186	for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
187	    ;
188	l->l_prev = prev;
189	prev->l_next = l;
190    }
191}
192
193static void
194link_elf_delete_gdb(struct link_map *l)
195{
196    if (l->l_prev == NULL) {
197	/* Remove first. */
198	if ((r_debug.r_map = l->l_next) != NULL)
199	    l->l_next->l_prev = NULL;
200    } else {
201	/* Remove any but first. */
202	if ((l->l_prev->l_next = l->l_next) != NULL)
203	    l->l_next->l_prev = l->l_prev;
204    }
205}
206#endif /* GDB */
207
208#ifdef __ia64__
209Elf_Addr link_elf_get_gp(linker_file_t);
210#endif
211
212/*
213 * The kernel symbol table starts here.
214 */
215extern struct _dynamic _DYNAMIC;
216
217static void
218link_elf_error(const char *s)
219{
220    printf("kldload: %s\n", s);
221}
222
223/*
224 * Actions performed after linking/loading both the preloaded kernel and any
225 * modules; whether preloaded or dynamicly loaded.
226 */
227static int
228link_elf_link_common_finish(linker_file_t lf)
229{
230#ifdef GDB
231    elf_file_t ef = (elf_file_t)lf;
232    char *newfilename;
233#endif
234    int error;
235
236    /* Notify MD code that a module is being loaded. */
237    error = elf_cpu_load_file(lf);
238    if (error)
239	return (error);
240
241#ifdef GDB
242    GDB_STATE(RT_ADD);
243    ef->gdb.l_addr = lf->address;
244    newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
245    strcpy(newfilename, lf->filename);
246    ef->gdb.l_name = newfilename;
247    ef->gdb.l_ld = ef->dynamic;
248    link_elf_add_gdb(&ef->gdb);
249    GDB_STATE(RT_CONSISTENT);
250#endif
251
252    return (0);
253}
254
255static void
256link_elf_init(void* arg)
257{
258    Elf_Dyn	*dp;
259    caddr_t	modptr, baseptr, sizeptr;
260    elf_file_t	ef;
261    char	*modname;
262
263    linker_add_class(&link_elf_class);
264
265    dp = (Elf_Dyn*) &_DYNAMIC;
266    modname = NULL;
267    modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
268    if (modptr == NULL)
269	modptr = preload_search_by_type("elf kernel");
270    if (modptr)
271	modname = (char *)preload_search_info(modptr, MODINFO_NAME);
272    if (modname == NULL)
273	modname = "kernel";
274    linker_kernel_file = linker_make_file(modname, &link_elf_class);
275    if (linker_kernel_file == NULL)
276	panic("link_elf_init: Can't create linker structures for kernel");
277
278    ef = (elf_file_t) linker_kernel_file;
279    ef->preloaded = 1;
280    ef->address = 0;
281#ifdef SPARSE_MAPPING
282    ef->object = 0;
283#endif
284    ef->dynamic = dp;
285
286    if (dp)
287	parse_dynamic(ef);
288    linker_kernel_file->address = (caddr_t) KERNBASE;
289    linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
290
291    if (modptr) {
292	ef->modptr = modptr;
293	baseptr = preload_search_info(modptr, MODINFO_ADDR);
294	if (baseptr)
295	    linker_kernel_file->address = *(caddr_t *)baseptr;
296	sizeptr = preload_search_info(modptr, MODINFO_SIZE);
297	if (sizeptr)
298	    linker_kernel_file->size = *(size_t *)sizeptr;
299    }
300    (void)link_elf_preload_parse_symbols(ef);
301
302#ifdef GDB
303    r_debug.r_map = NULL;
304    r_debug.r_brk = r_debug_state;
305    r_debug.r_state = RT_CONSISTENT;
306#endif
307
308    (void)link_elf_link_common_finish(linker_kernel_file);
309}
310
311SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, 0);
312
313static int
314link_elf_preload_parse_symbols(elf_file_t ef)
315{
316    caddr_t	pointer;
317    caddr_t	ssym, esym, base;
318    caddr_t	strtab;
319    int		strcnt;
320    Elf_Sym*	symtab;
321    int		symcnt;
322
323    if (ef->modptr == NULL)
324	return 0;
325    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
326    if (pointer == NULL)
327	return 0;
328    ssym = *(caddr_t *)pointer;
329    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
330    if (pointer == NULL)
331	return 0;
332    esym = *(caddr_t *)pointer;
333
334    base = ssym;
335
336    symcnt = *(long *)base;
337    base += sizeof(long);
338    symtab = (Elf_Sym *)base;
339    base += roundup(symcnt, sizeof(long));
340
341    if (base > esym || base < ssym) {
342	printf("Symbols are corrupt!\n");
343	return EINVAL;
344    }
345
346    strcnt = *(long *)base;
347    base += sizeof(long);
348    strtab = base;
349    base += roundup(strcnt, sizeof(long));
350
351    if (base > esym || base < ssym) {
352	printf("Symbols are corrupt!\n");
353	return EINVAL;
354    }
355
356    ef->ddbsymtab = symtab;
357    ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
358    ef->ddbstrtab = strtab;
359    ef->ddbstrcnt = strcnt;
360
361    return 0;
362}
363
364static int
365parse_dynamic(elf_file_t ef)
366{
367    Elf_Dyn *dp;
368    int plttype = DT_REL;
369
370    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
371	switch (dp->d_tag) {
372	case DT_HASH:
373	{
374	    /* From src/libexec/rtld-elf/rtld.c */
375	    const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
376		(ef->address + dp->d_un.d_ptr);
377	    ef->nbuckets = hashtab[0];
378	    ef->nchains = hashtab[1];
379	    ef->buckets = hashtab + 2;
380	    ef->chains = ef->buckets + ef->nbuckets;
381	    break;
382	}
383	case DT_STRTAB:
384	    ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
385	    break;
386	case DT_STRSZ:
387	    ef->strsz = dp->d_un.d_val;
388	    break;
389	case DT_SYMTAB:
390	    ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
391	    break;
392	case DT_SYMENT:
393	    if (dp->d_un.d_val != sizeof(Elf_Sym))
394		return ENOEXEC;
395	    break;
396	case DT_PLTGOT:
397	    ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
398	    break;
399	case DT_REL:
400	    ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
401	    break;
402	case DT_RELSZ:
403	    ef->relsize = dp->d_un.d_val;
404	    break;
405	case DT_RELENT:
406	    if (dp->d_un.d_val != sizeof(Elf_Rel))
407		return ENOEXEC;
408	    break;
409	case DT_JMPREL:
410	    ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
411	    break;
412	case DT_PLTRELSZ:
413	    ef->pltrelsize = dp->d_un.d_val;
414	    break;
415	case DT_RELA:
416	    ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
417	    break;
418	case DT_RELASZ:
419	    ef->relasize = dp->d_un.d_val;
420	    break;
421	case DT_RELAENT:
422	    if (dp->d_un.d_val != sizeof(Elf_Rela))
423		return ENOEXEC;
424	    break;
425	case DT_PLTREL:
426	    plttype = dp->d_un.d_val;
427	    if (plttype != DT_REL && plttype != DT_RELA)
428		return ENOEXEC;
429	    break;
430#ifdef GDB
431	case DT_DEBUG:
432	    dp->d_un.d_ptr = (Elf_Addr) &r_debug;
433	    break;
434#endif
435	}
436    }
437
438    if (plttype == DT_RELA) {
439	ef->pltrela = (const Elf_Rela *) ef->pltrel;
440	ef->pltrel = NULL;
441	ef->pltrelasize = ef->pltrelsize;
442	ef->pltrelsize = 0;
443    }
444
445    ef->ddbsymtab = ef->symtab;
446    ef->ddbsymcnt = ef->nchains;
447    ef->ddbstrtab = ef->strtab;
448    ef->ddbstrcnt = ef->strsz;
449
450    return 0;
451}
452
453static int
454link_elf_link_preload(linker_class_t cls,
455		      const char* filename, linker_file_t *result)
456{
457    caddr_t		modptr, baseptr, sizeptr, dynptr;
458    char		*type;
459    elf_file_t		ef;
460    linker_file_t	lf;
461    int			error;
462    vm_offset_t		dp;
463
464    /* Look to see if we have the file preloaded */
465    modptr = preload_search_by_name(filename);
466    if (modptr == NULL)
467	return ENOENT;
468
469    type = (char *)preload_search_info(modptr, MODINFO_TYPE);
470    baseptr = preload_search_info(modptr, MODINFO_ADDR);
471    sizeptr = preload_search_info(modptr, MODINFO_SIZE);
472    dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
473    if (type == NULL ||
474	(strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
475	 strcmp(type, "elf module") != 0))
476	return (EFTYPE);
477    if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
478	return (EINVAL);
479
480    lf = linker_make_file(filename, &link_elf_class);
481    if (lf == NULL) {
482	return ENOMEM;
483    }
484
485    ef = (elf_file_t) lf;
486    ef->preloaded = 1;
487    ef->modptr = modptr;
488    ef->address = *(caddr_t *)baseptr;
489#ifdef SPARSE_MAPPING
490    ef->object = 0;
491#endif
492    dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
493    ef->dynamic = (Elf_Dyn *)dp;
494    lf->address = ef->address;
495    lf->size = *(size_t *)sizeptr;
496
497    error = parse_dynamic(ef);
498    if (error) {
499	linker_file_unload(lf, LINKER_UNLOAD_FORCE);
500	return error;
501    }
502    link_elf_reloc_local(lf);
503    *result = lf;
504    return (0);
505}
506
507static int
508link_elf_link_preload_finish(linker_file_t lf)
509{
510    elf_file_t		ef;
511    int error;
512
513    ef = (elf_file_t) lf;
514#if 0	/* this will be more trouble than it's worth for now */
515    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
516	if (dp->d_tag != DT_NEEDED)
517	    continue;
518	modname = ef->strtab + dp->d_un.d_val;
519	error = linker_load_module(modname, lf);
520	if (error)
521	    goto out;
522    }
523#endif
524    error = relocate_file(ef);
525    if (error)
526	return error;
527    (void)link_elf_preload_parse_symbols(ef);
528
529    return (link_elf_link_common_finish(lf));
530}
531
532static int
533link_elf_load_file(linker_class_t cls, const char* filename,
534	linker_file_t* result)
535{
536    struct nameidata nd;
537    struct thread* td = curthread;	/* XXX */
538    Elf_Ehdr *hdr;
539    caddr_t firstpage;
540    int nbytes, i;
541    Elf_Phdr *phdr;
542    Elf_Phdr *phlimit;
543    Elf_Phdr *segs[MAXSEGS];
544    int nsegs;
545    Elf_Phdr *phdyn;
546    Elf_Phdr *phphdr;
547    caddr_t mapbase;
548    size_t mapsize;
549    Elf_Off base_offset;
550    Elf_Addr base_vaddr;
551    Elf_Addr base_vlimit;
552    int error = 0;
553    int resid, flags;
554    elf_file_t ef;
555    linker_file_t lf;
556    Elf_Shdr *shdr;
557    int symtabindex;
558    int symstrindex;
559    int symcnt;
560    int strcnt;
561    int vfslocked;
562
563    shdr = NULL;
564    lf = NULL;
565
566    NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, filename, td);
567    flags = FREAD;
568    error = vn_open(&nd, &flags, 0, -1);
569    if (error)
570	return error;
571    vfslocked = NDHASGIANT(&nd);
572    NDFREE(&nd, NDF_ONLY_PNBUF);
573#ifdef MAC
574    error = mac_check_kld_load(curthread->td_ucred, nd.ni_vp);
575    if (error) {
576	firstpage = NULL;
577	goto out;
578    }
579#endif
580
581    /*
582     * Read the elf header from the file.
583     */
584    firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
585    if (firstpage == NULL) {
586	error = ENOMEM;
587	goto out;
588    }
589    hdr = (Elf_Ehdr *)firstpage;
590    error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
591		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
592		    &resid, td);
593    nbytes = PAGE_SIZE - resid;
594    if (error)
595	goto out;
596
597    if (!IS_ELF(*hdr)) {
598	error = ENOEXEC;
599	goto out;
600    }
601
602    if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
603      || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
604	link_elf_error("Unsupported file layout");
605	error = ENOEXEC;
606	goto out;
607    }
608    if (hdr->e_ident[EI_VERSION] != EV_CURRENT
609      || hdr->e_version != EV_CURRENT) {
610	link_elf_error("Unsupported file version");
611	error = ENOEXEC;
612	goto out;
613    }
614    if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
615	link_elf_error("Unsupported file type");
616	error = ENOEXEC;
617	goto out;
618    }
619    if (hdr->e_machine != ELF_TARG_MACH) {
620	link_elf_error("Unsupported machine");
621	error = ENOEXEC;
622	goto out;
623    }
624
625    /*
626     * We rely on the program header being in the first page.  This is
627     * not strictly required by the ABI specification, but it seems to
628     * always true in practice.  And, it simplifies things considerably.
629     */
630    if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
631	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
632	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
633	link_elf_error("Unreadable program headers");
634
635    /*
636     * Scan the program header entries, and save key information.
637     *
638     * We rely on there being exactly two load segments, text and data,
639     * in that order.
640     */
641    phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
642    phlimit = phdr + hdr->e_phnum;
643    nsegs = 0;
644    phdyn = NULL;
645    phphdr = NULL;
646    while (phdr < phlimit) {
647	switch (phdr->p_type) {
648
649	case PT_LOAD:
650	    if (nsegs == MAXSEGS) {
651		link_elf_error("Too many sections");
652		error = ENOEXEC;
653		goto out;
654	    }
655	    /*
656	     * XXX: We just trust they come in right order ??
657	     */
658	    segs[nsegs] = phdr;
659	    ++nsegs;
660	    break;
661
662	case PT_PHDR:
663	    phphdr = phdr;
664	    break;
665
666	case PT_DYNAMIC:
667	    phdyn = phdr;
668	    break;
669
670	case PT_INTERP:
671	    link_elf_error("Unsupported file type");
672	    error = ENOEXEC;
673	    goto out;
674	}
675
676	++phdr;
677    }
678    if (phdyn == NULL) {
679	link_elf_error("Object is not dynamically-linked");
680	error = ENOEXEC;
681	goto out;
682    }
683    if (nsegs == 0) {
684	link_elf_error("No sections");
685	error = ENOEXEC;
686	goto out;
687    }
688
689    /*
690     * Allocate the entire address space of the object, to stake out our
691     * contiguous region, and to establish the base address for relocation.
692     */
693    base_offset = trunc_page(segs[0]->p_offset);
694    base_vaddr = trunc_page(segs[0]->p_vaddr);
695    base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
696	segs[nsegs - 1]->p_memsz);
697    mapsize = base_vlimit - base_vaddr;
698
699    lf = linker_make_file(filename, &link_elf_class);
700    if (!lf) {
701	error = ENOMEM;
702	goto out;
703    }
704
705    ef = (elf_file_t) lf;
706#ifdef SPARSE_MAPPING
707    ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
708    if (ef->object == NULL) {
709	error = ENOMEM;
710	goto out;
711    }
712    ef->address = (caddr_t) vm_map_min(kernel_map);
713    error = vm_map_find(kernel_map, ef->object, 0,
714			(vm_offset_t *) &ef->address,
715			mapsize, 1,
716			VM_PROT_ALL, VM_PROT_ALL, 0);
717    if (error) {
718	vm_object_deallocate(ef->object);
719	ef->object = 0;
720	goto out;
721    }
722#else
723    ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
724    if (!ef->address) {
725	error = ENOMEM;
726	goto out;
727    }
728#endif
729    mapbase = ef->address;
730
731    /*
732     * Read the text and data sections and zero the bss.
733     */
734    for (i = 0; i < nsegs; i++) {
735	caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
736	error = vn_rdwr(UIO_READ, nd.ni_vp,
737			segbase, segs[i]->p_filesz, segs[i]->p_offset,
738			UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
739			&resid, td);
740	if (error) {
741	    goto out;
742	}
743	bzero(segbase + segs[i]->p_filesz,
744	      segs[i]->p_memsz - segs[i]->p_filesz);
745
746#ifdef SPARSE_MAPPING
747	/*
748	 * Wire down the pages
749	 */
750	error = vm_map_wire(kernel_map,
751		    (vm_offset_t) segbase,
752		    (vm_offset_t) segbase + segs[i]->p_memsz,
753		    VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
754	if (error != KERN_SUCCESS) {
755	    error = ENOMEM;
756	    goto out;
757	}
758#endif
759    }
760
761#ifdef GPROF
762    /* Update profiling information with the new text segment. */
763    mtx_lock(&Giant);
764    kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
765	segs[0]->p_memsz));
766    mtx_unlock(&Giant);
767#endif
768
769    ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
770
771    lf->address = ef->address;
772    lf->size = mapsize;
773
774    error = parse_dynamic(ef);
775    if (error)
776	goto out;
777    link_elf_reloc_local(lf);
778
779    error = linker_load_dependencies(lf);
780    if (error)
781	goto out;
782#if 0	/* this will be more trouble than it's worth for now */
783    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
784	if (dp->d_tag != DT_NEEDED)
785	    continue;
786	modname = ef->strtab + dp->d_un.d_val;
787	error = linker_load_module(modname, lf);
788	if (error)
789	    goto out;
790    }
791#endif
792    error = relocate_file(ef);
793    if (error)
794	goto out;
795
796    /* Try and load the symbol table if it's present.  (you can strip it!) */
797    nbytes = hdr->e_shnum * hdr->e_shentsize;
798    if (nbytes == 0 || hdr->e_shoff == 0)
799	goto nosyms;
800    shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
801    if (shdr == NULL) {
802	error = ENOMEM;
803	goto out;
804    }
805    error = vn_rdwr(UIO_READ, nd.ni_vp,
806		    (caddr_t)shdr, nbytes, hdr->e_shoff,
807		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
808		    &resid, td);
809    if (error)
810	goto out;
811    symtabindex = -1;
812    symstrindex = -1;
813    for (i = 0; i < hdr->e_shnum; i++) {
814	if (shdr[i].sh_type == SHT_SYMTAB) {
815	    symtabindex = i;
816	    symstrindex = shdr[i].sh_link;
817	}
818    }
819    if (symtabindex < 0 || symstrindex < 0)
820	goto nosyms;
821
822    symcnt = shdr[symtabindex].sh_size;
823    ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
824    strcnt = shdr[symstrindex].sh_size;
825    ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
826
827    if (ef->symbase == NULL || ef->strbase == NULL) {
828	error = ENOMEM;
829	goto out;
830    }
831    error = vn_rdwr(UIO_READ, nd.ni_vp,
832		    ef->symbase, symcnt, shdr[symtabindex].sh_offset,
833		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
834		    &resid, td);
835    if (error)
836	goto out;
837    error = vn_rdwr(UIO_READ, nd.ni_vp,
838		    ef->strbase, strcnt, shdr[symstrindex].sh_offset,
839		    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
840		    &resid, td);
841    if (error)
842	goto out;
843
844    ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
845    ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
846    ef->ddbstrcnt = strcnt;
847    ef->ddbstrtab = ef->strbase;
848
849    error = link_elf_link_common_finish(lf);
850    if (error)
851	goto out;
852
853nosyms:
854
855    *result = lf;
856
857out:
858    if (error && lf)
859	linker_file_unload(lf, LINKER_UNLOAD_FORCE);
860    if (shdr)
861	free(shdr, M_LINKER);
862    if (firstpage)
863	free(firstpage, M_LINKER);
864    VOP_UNLOCK(nd.ni_vp, 0, td);
865    vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
866    VFS_UNLOCK_GIANT(vfslocked);
867
868    return error;
869}
870
871static void
872link_elf_unload_file(linker_file_t file)
873{
874    elf_file_t ef = (elf_file_t) file;
875
876#ifdef GDB
877    if (ef->gdb.l_ld) {
878	GDB_STATE(RT_DELETE);
879	free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
880	link_elf_delete_gdb(&ef->gdb);
881	GDB_STATE(RT_CONSISTENT);
882    }
883#endif
884
885    /* Notify MD code that a module is being unloaded. */
886    elf_cpu_unload_file(file);
887
888    if (ef->preloaded) {
889	link_elf_unload_preload(file);
890	return;
891    }
892
893#ifdef SPARSE_MAPPING
894    if (ef->object) {
895	vm_map_remove(kernel_map, (vm_offset_t) ef->address,
896		      (vm_offset_t) ef->address
897		      + (ef->object->size << PAGE_SHIFT));
898    }
899#else
900    if (ef->address)
901	free(ef->address, M_LINKER);
902#endif
903    if (ef->symbase)
904	free(ef->symbase, M_LINKER);
905    if (ef->strbase)
906	free(ef->strbase, M_LINKER);
907}
908
909static void
910link_elf_unload_preload(linker_file_t file)
911{
912    if (file->filename)
913	preload_delete_name(file->filename);
914}
915
916static const char *
917symbol_name(elf_file_t ef, Elf_Size r_info)
918{
919    const Elf_Sym *ref;
920
921    if (ELF_R_SYM(r_info)) {
922	ref = ef->symtab + ELF_R_SYM(r_info);
923	return ef->strtab + ref->st_name;
924    } else
925	return NULL;
926}
927
928static int
929relocate_file(elf_file_t ef)
930{
931    const Elf_Rel *rellim;
932    const Elf_Rel *rel;
933    const Elf_Rela *relalim;
934    const Elf_Rela *rela;
935    const char *symname;
936
937    /* Perform relocations without addend if there are any: */
938    rel = ef->rel;
939    if (rel) {
940	rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
941	while (rel < rellim) {
942	    if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
943			  elf_lookup)) {
944		symname = symbol_name(ef, rel->r_info);
945		printf("link_elf: symbol %s undefined\n", symname);
946		return ENOENT;
947	    }
948	    rel++;
949	}
950    }
951
952    /* Perform relocations with addend if there are any: */
953    rela = ef->rela;
954    if (rela) {
955	relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
956	while (rela < relalim) {
957	    if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
958			  elf_lookup)) {
959		symname = symbol_name(ef, rela->r_info);
960		printf("link_elf: symbol %s undefined\n", symname);
961		return ENOENT;
962	    }
963	    rela++;
964	}
965    }
966
967    /* Perform PLT relocations without addend if there are any: */
968    rel = ef->pltrel;
969    if (rel) {
970	rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize);
971	while (rel < rellim) {
972	    if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
973			  elf_lookup)) {
974		symname = symbol_name(ef, rel->r_info);
975		printf("link_elf: symbol %s undefined\n", symname);
976		return ENOENT;
977	    }
978	    rel++;
979	}
980    }
981
982    /* Perform relocations with addend if there are any: */
983    rela = ef->pltrela;
984    if (rela) {
985	relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize);
986	while (rela < relalim) {
987	    if (elf_reloc(&ef->lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
988			  elf_lookup)) {
989		symname = symbol_name(ef, rela->r_info);
990		printf("link_elf: symbol %s undefined\n", symname);
991		return ENOENT;
992	    }
993	    rela++;
994	}
995    }
996
997    return 0;
998}
999
1000/*
1001 * Hash function for symbol table lookup.  Don't even think about changing
1002 * this.  It is specified by the System V ABI.
1003 */
1004static unsigned long
1005elf_hash(const char *name)
1006{
1007    const unsigned char *p = (const unsigned char *) name;
1008    unsigned long h = 0;
1009    unsigned long g;
1010
1011    while (*p != '\0') {
1012	h = (h << 4) + *p++;
1013	if ((g = h & 0xf0000000) != 0)
1014	    h ^= g >> 24;
1015	h &= ~g;
1016    }
1017    return h;
1018}
1019
1020static int
1021link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym)
1022{
1023    elf_file_t ef = (elf_file_t) lf;
1024    unsigned long symnum;
1025    const Elf_Sym* symp;
1026    const char *strp;
1027    unsigned long hash;
1028    int i;
1029
1030    /* If we don't have a hash, bail. */
1031    if (ef->buckets == NULL || ef->nbuckets == 0) {
1032	printf("link_elf_lookup_symbol: missing symbol hash table\n");
1033	return ENOENT;
1034    }
1035
1036    /* First, search hashed global symbols */
1037    hash = elf_hash(name);
1038    symnum = ef->buckets[hash % ef->nbuckets];
1039
1040    while (symnum != STN_UNDEF) {
1041	if (symnum >= ef->nchains) {
1042	    printf("link_elf_lookup_symbol: corrupt symbol table\n");
1043	    return ENOENT;
1044	}
1045
1046	symp = ef->symtab + symnum;
1047	if (symp->st_name == 0) {
1048	    printf("link_elf_lookup_symbol: corrupt symbol table\n");
1049	    return ENOENT;
1050	}
1051
1052	strp = ef->strtab + symp->st_name;
1053
1054	if (strcmp(name, strp) == 0) {
1055	    if (symp->st_shndx != SHN_UNDEF ||
1056		(symp->st_value != 0 &&
1057		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1058		*sym = (c_linker_sym_t) symp;
1059		return 0;
1060	    } else
1061		return ENOENT;
1062	}
1063
1064	symnum = ef->chains[symnum];
1065    }
1066
1067    /* If we have not found it, look at the full table (if loaded) */
1068    if (ef->symtab == ef->ddbsymtab)
1069	return ENOENT;
1070
1071    /* Exhaustive search */
1072    for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1073	strp = ef->ddbstrtab + symp->st_name;
1074	if (strcmp(name, strp) == 0) {
1075	    if (symp->st_shndx != SHN_UNDEF ||
1076		(symp->st_value != 0 &&
1077		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
1078		*sym = (c_linker_sym_t) symp;
1079		return 0;
1080	    } else
1081		return ENOENT;
1082	}
1083    }
1084
1085    return ENOENT;
1086}
1087
1088static int
1089link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval)
1090{
1091	elf_file_t ef = (elf_file_t) lf;
1092	const Elf_Sym* es = (const Elf_Sym*) sym;
1093
1094	if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1095	    symval->name = ef->strtab + es->st_name;
1096	    symval->value = (caddr_t) ef->address + es->st_value;
1097	    symval->size = es->st_size;
1098	    return 0;
1099	}
1100	if (ef->symtab == ef->ddbsymtab)
1101	    return ENOENT;
1102	if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1103	    symval->name = ef->ddbstrtab + es->st_name;
1104	    symval->value = (caddr_t) ef->address + es->st_value;
1105	    symval->size = es->st_size;
1106	    return 0;
1107	}
1108	return ENOENT;
1109}
1110
1111static int
1112link_elf_search_symbol(linker_file_t lf, caddr_t value,
1113		       c_linker_sym_t* sym, long* diffp)
1114{
1115	elf_file_t ef = (elf_file_t) lf;
1116	u_long off = (uintptr_t) (void *) value;
1117	u_long diff = off;
1118	u_long st_value;
1119	const Elf_Sym* es;
1120	const Elf_Sym* best = 0;
1121	int i;
1122
1123	for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1124		if (es->st_name == 0)
1125			continue;
1126		st_value = es->st_value + (uintptr_t) (void *) ef->address;
1127		if (off >= st_value) {
1128			if (off - st_value < diff) {
1129				diff = off - st_value;
1130				best = es;
1131				if (diff == 0)
1132					break;
1133			} else if (off - st_value == diff) {
1134				best = es;
1135			}
1136		}
1137	}
1138	if (best == 0)
1139		*diffp = off;
1140	else
1141		*diffp = diff;
1142	*sym = (c_linker_sym_t) best;
1143
1144	return 0;
1145}
1146
1147/*
1148 * Look up a linker set on an ELF system.
1149 */
1150static int
1151link_elf_lookup_set(linker_file_t lf, const char *name,
1152		    void ***startp, void ***stopp, int *countp)
1153{
1154	c_linker_sym_t sym;
1155	linker_symval_t symval;
1156	char *setsym;
1157	void **start, **stop;
1158	int len, error = 0, count;
1159
1160	len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1161	setsym = malloc(len, M_LINKER, M_WAITOK);
1162	if (setsym == NULL)
1163		return ENOMEM;
1164
1165	/* get address of first entry */
1166	snprintf(setsym, len, "%s%s", "__start_set_", name);
1167	error = link_elf_lookup_symbol(lf, setsym, &sym);
1168	if (error)
1169		goto out;
1170	link_elf_symbol_values(lf, sym, &symval);
1171	if (symval.value == 0) {
1172		error = ESRCH;
1173		goto out;
1174	}
1175	start = (void **)symval.value;
1176
1177	/* get address of last entry */
1178	snprintf(setsym, len, "%s%s", "__stop_set_", name);
1179	error = link_elf_lookup_symbol(lf, setsym, &sym);
1180	if (error)
1181		goto out;
1182	link_elf_symbol_values(lf, sym, &symval);
1183	if (symval.value == 0) {
1184		error = ESRCH;
1185		goto out;
1186	}
1187	stop = (void **)symval.value;
1188
1189	/* and the number of entries */
1190	count = stop - start;
1191
1192	/* and copy out */
1193	if (startp)
1194		*startp = start;
1195	if (stopp)
1196		*stopp = stop;
1197	if (countp)
1198		*countp = count;
1199
1200out:
1201	free(setsym, M_LINKER);
1202	return error;
1203}
1204
1205static int
1206link_elf_each_function_name(linker_file_t file,
1207  int (*callback)(const char *, void *), void *opaque) {
1208    elf_file_t ef = (elf_file_t)file;
1209    const Elf_Sym* symp;
1210    int i, error;
1211
1212    /* Exhaustive search */
1213    for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1214	if (symp->st_value != 0 &&
1215	    ELF_ST_TYPE(symp->st_info) == STT_FUNC) {
1216		error = callback(ef->ddbstrtab + symp->st_name, opaque);
1217		if (error)
1218		    return (error);
1219	}
1220    }
1221    return (0);
1222}
1223
1224#ifdef __ia64__
1225/*
1226 * Each KLD has its own GP. The GP value for each load module is given by
1227 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but
1228 * don't have direct access to the ELF file structure. The link_elf_get_gp()
1229 * function returns the GP given a pointer to a generic linker file struct.
1230 */
1231Elf_Addr
1232link_elf_get_gp(linker_file_t lf)
1233{
1234	elf_file_t ef = (elf_file_t)lf;
1235	return (Elf_Addr)ef->got;
1236}
1237#endif
1238
1239const Elf_Sym *
1240elf_get_sym(linker_file_t lf, Elf_Size symidx)
1241{
1242	elf_file_t ef = (elf_file_t)lf;
1243
1244	if (symidx >= ef->nchains)
1245		return (NULL);
1246	return (ef->symtab + symidx);
1247}
1248
1249const char *
1250elf_get_symname(linker_file_t lf, Elf_Size symidx)
1251{
1252	elf_file_t ef = (elf_file_t)lf;
1253	const Elf_Sym *sym;
1254
1255	if (symidx >= ef->nchains)
1256		return (NULL);
1257	sym = ef->symtab + symidx;
1258	return (ef->strtab + sym->st_name);
1259}
1260
1261/*
1262 * Symbol lookup function that can be used when the symbol index is known (ie
1263 * in relocations). It uses the symbol index instead of doing a fully fledged
1264 * hash table based lookup when such is valid. For example for local symbols.
1265 * This is not only more efficient, it's also more correct. It's not always
1266 * the case that the symbol can be found through the hash table.
1267 */
1268static Elf_Addr
1269elf_lookup(linker_file_t lf, Elf_Size symidx, int deps)
1270{
1271	elf_file_t ef = (elf_file_t)lf;
1272	const Elf_Sym *sym;
1273	const char *symbol;
1274
1275	/* Don't even try to lookup the symbol if the index is bogus. */
1276	if (symidx >= ef->nchains)
1277		return (0);
1278
1279	sym = ef->symtab + symidx;
1280
1281	/*
1282	 * Don't do a full lookup when the symbol is local. It may even
1283	 * fail because it may not be found through the hash table.
1284	 */
1285	if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1286		/* Force lookup failure when we have an insanity. */
1287		if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0)
1288			return (0);
1289		return ((Elf_Addr)ef->address + sym->st_value);
1290	}
1291
1292	/*
1293	 * XXX we can avoid doing a hash table based lookup for global
1294	 * symbols as well. This however is not always valid, so we'll
1295	 * just do it the hard way for now. Performance tweaks can
1296	 * always be added.
1297	 */
1298
1299	symbol = ef->strtab + sym->st_name;
1300
1301	/* Force a lookup failure if the symbol name is bogus. */
1302	if (*symbol == 0)
1303		return (0);
1304
1305	return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1306}
1307
1308static void
1309link_elf_reloc_local(linker_file_t lf)
1310{
1311    const Elf_Rel *rellim;
1312    const Elf_Rel *rel;
1313    const Elf_Rela *relalim;
1314    const Elf_Rela *rela;
1315    elf_file_t ef = (elf_file_t)lf;
1316
1317    /* Perform relocations without addend if there are any: */
1318    if ((rel = ef->rel) != NULL) {
1319	rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1320	while (rel < rellim) {
1321	    elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL,
1322			    elf_lookup);
1323	    rel++;
1324	}
1325    }
1326
1327    /* Perform relocations with addend if there are any: */
1328    if ((rela = ef->rela) != NULL) {
1329	relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize);
1330	while (rela < relalim) {
1331	    elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA,
1332			    elf_lookup);
1333	    rela++;
1334	}
1335    }
1336}
1337