link_elf.c revision 85734 
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 85734 2001-10-30 15:08:51Z green $
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 */
164extern struct _dynamic _DYNAMIC;
165
166static void
167link_elf_init(void* arg)
168{
169#ifdef __ELF__
170    Elf_Dyn	*dp;
171    caddr_t	modptr, baseptr, sizeptr;
172    elf_file_t	ef;
173    char	*modname;
174#ifdef DDB
175    char *newfilename;
176#endif
177#endif
178
179    linker_add_class(&link_elf_class);
180
181#ifdef __ELF__
182    dp = (Elf_Dyn*) &_DYNAMIC;
183    modname = NULL;
184    modptr = preload_search_by_type("elf kernel");
185    if (modptr)
186	modname = (char *)preload_search_info(modptr, MODINFO_NAME);
187    if (modname == NULL)
188	modname = "kernel";
189    linker_kernel_file = linker_make_file(modname, &link_elf_class);
190    if (linker_kernel_file == NULL)
191	panic("link_elf_init: Can't create linker structures for kernel");
192
193    ef = (elf_file_t) linker_kernel_file;
194    ef->preloaded = 1;
195    ef->address = 0;
196#ifdef SPARSE_MAPPING
197    ef->object = 0;
198#endif
199    ef->dynamic = dp;
200
201    if (dp)
202	parse_dynamic(ef);
203    linker_kernel_file->address = (caddr_t) KERNBASE;
204    linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
205
206    if (modptr) {
207	ef->modptr = modptr;
208	baseptr = preload_search_info(modptr, MODINFO_ADDR);
209	if (baseptr)
210	    linker_kernel_file->address = *(caddr_t *)baseptr;
211	sizeptr = preload_search_info(modptr, MODINFO_SIZE);
212	if (sizeptr)
213	    linker_kernel_file->size = *(size_t *)sizeptr;
214    }
215    (void)link_elf_preload_parse_symbols(ef);
216
217#ifdef DDB
218    ef->gdb.l_addr = linker_kernel_file->address;
219    newfilename = malloc(strlen(modname) + 1, M_LINKER, M_WAITOK);
220    strcpy(newfilename, modname);
221    ef->gdb.l_name = newfilename;
222    ef->gdb.l_ld = dp;
223    ef->gdb.l_prev = 0;
224    ef->gdb.l_next = 0;
225
226    r_debug.r_map = &ef->gdb;
227    r_debug.r_brk = r_debug_state;
228    r_debug.r_state = RT_CONSISTENT;
229
230    r_debug_state(NULL, NULL);	/* say hello to gdb! */
231#endif
232
233#endif
234}
235
236SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0);
237
238static int
239link_elf_preload_parse_symbols(elf_file_t ef)
240{
241    caddr_t	pointer;
242    caddr_t	ssym, esym, base;
243    caddr_t	strtab;
244    int		strcnt;
245    Elf_Sym*	symtab;
246    int		symcnt;
247
248    if (ef->modptr == NULL)
249	return 0;
250    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM);
251    if (pointer == NULL)
252	return 0;
253    ssym = *(caddr_t *)pointer;
254    pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM);
255    if (pointer == NULL)
256	return 0;
257    esym = *(caddr_t *)pointer;
258
259    base = ssym;
260
261    symcnt = *(long *)base;
262    base += sizeof(long);
263    symtab = (Elf_Sym *)base;
264    base += roundup(symcnt, sizeof(long));
265
266    if (base > esym || base < ssym) {
267	printf("Symbols are corrupt!\n");
268	return EINVAL;
269    }
270
271    strcnt = *(long *)base;
272    base += sizeof(long);
273    strtab = base;
274    base += roundup(strcnt, sizeof(long));
275
276    if (base > esym || base < ssym) {
277	printf("Symbols are corrupt!\n");
278	return EINVAL;
279    }
280
281    ef->ddbsymtab = symtab;
282    ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
283    ef->ddbstrtab = strtab;
284    ef->ddbstrcnt = strcnt;
285
286    return 0;
287}
288
289static int
290parse_dynamic(elf_file_t ef)
291{
292    Elf_Dyn *dp;
293    int plttype = DT_REL;
294
295    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
296	switch (dp->d_tag) {
297	case DT_HASH:
298	{
299	    /* From src/libexec/rtld-elf/rtld.c */
300	    const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
301		(ef->address + dp->d_un.d_ptr);
302	    ef->nbuckets = hashtab[0];
303	    ef->nchains = hashtab[1];
304	    ef->buckets = hashtab + 2;
305	    ef->chains = ef->buckets + ef->nbuckets;
306	    break;
307	}
308	case DT_STRTAB:
309	    ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
310	    break;
311	case DT_STRSZ:
312	    ef->strsz = dp->d_un.d_val;
313	    break;
314	case DT_SYMTAB:
315	    ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
316	    break;
317	case DT_SYMENT:
318	    if (dp->d_un.d_val != sizeof(Elf_Sym))
319		return ENOEXEC;
320	    break;
321	case DT_PLTGOT:
322	    ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
323	    break;
324	case DT_REL:
325	    ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
326	    break;
327	case DT_RELSZ:
328	    ef->relsize = dp->d_un.d_val;
329	    break;
330	case DT_RELENT:
331	    if (dp->d_un.d_val != sizeof(Elf_Rel))
332		return ENOEXEC;
333	    break;
334	case DT_JMPREL:
335	    ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
336	    break;
337	case DT_PLTRELSZ:
338	    ef->pltrelsize = dp->d_un.d_val;
339	    break;
340	case DT_RELA:
341	    ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
342	    break;
343	case DT_RELASZ:
344	    ef->relasize = dp->d_un.d_val;
345	    break;
346	case DT_RELAENT:
347	    if (dp->d_un.d_val != sizeof(Elf_Rela))
348		return ENOEXEC;
349	    break;
350	case DT_PLTREL:
351	    plttype = dp->d_un.d_val;
352	    if (plttype != DT_REL && plttype != DT_RELA)
353		return ENOEXEC;
354	    break;
355#ifdef DDB
356	case DT_DEBUG:
357	    dp->d_un.d_ptr = (Elf_Addr) &r_debug;
358	    break;
359#endif
360	}
361    }
362
363    if (plttype == DT_RELA) {
364	ef->pltrela = (const Elf_Rela *) ef->pltrel;
365	ef->pltrel = NULL;
366	ef->pltrelasize = ef->pltrelsize;
367	ef->pltrelsize = 0;
368    }
369
370    ef->ddbsymtab = ef->symtab;
371    ef->ddbsymcnt = ef->nchains;
372    ef->ddbstrtab = ef->strtab;
373    ef->ddbstrcnt = ef->strsz;
374
375    return 0;
376}
377
378static void
379link_elf_error(const char *s)
380{
381    printf("kldload: %s\n", s);
382}
383
384#ifdef DDB
385
386static void
387link_elf_add_gdb(struct link_map *l)
388{
389    struct link_map *prev;
390
391    /*
392     * Scan to the end of the list.
393     */
394    for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next)
395	;
396
397    /* Link in the new entry. */
398    l->l_prev = prev;
399    l->l_next = prev->l_next;
400    prev->l_next = l;
401}
402
403static void
404link_elf_delete_gdb(struct link_map *l)
405{
406    if (l->l_prev == NULL) {
407	if ((r_debug.r_map = l->l_next) != NULL)
408	    l->l_next->l_prev = NULL;
409	return;
410    }
411
412    if ((l->l_prev->l_next = l->l_next) != NULL)
413	l->l_next->l_prev = l->l_prev;
414}
415
416#endif /* DDB */
417
418static int
419link_elf_link_preload(linker_class_t cls,
420		      const char* filename, linker_file_t *result)
421{
422    caddr_t		modptr, baseptr, sizeptr, dynptr;
423    char		*type;
424    elf_file_t		ef;
425    linker_file_t	lf;
426    int			error;
427    vm_offset_t		dp;
428
429    /* Look to see if we have the file preloaded */
430    modptr = preload_search_by_name(filename);
431    if (modptr == NULL)
432	return ENOENT;
433
434    type = (char *)preload_search_info(modptr, MODINFO_TYPE);
435    baseptr = preload_search_info(modptr, MODINFO_ADDR);
436    sizeptr = preload_search_info(modptr, MODINFO_SIZE);
437    dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC);
438    if (type == NULL || strcmp(type, "elf module") != 0)
439	return (EFTYPE);
440    if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
441	return (EINVAL);
442
443    lf = linker_make_file(filename, &link_elf_class);
444    if (lf == NULL) {
445	return ENOMEM;
446    }
447
448    ef = (elf_file_t) lf;
449    ef->preloaded = 1;
450    ef->modptr = modptr;
451    ef->address = *(caddr_t *)baseptr;
452#ifdef SPARSE_MAPPING
453    ef->object = 0;
454#endif
455    dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
456    ef->dynamic = (Elf_Dyn *)dp;
457    lf->address = ef->address;
458    lf->size = *(size_t *)sizeptr;
459
460    error = parse_dynamic(ef);
461    if (error) {
462	linker_file_unload(lf);
463	return error;
464    }
465    *result = lf;
466    return (0);
467}
468
469static int
470link_elf_link_preload_finish(linker_file_t lf)
471{
472    elf_file_t		ef;
473    int error;
474#ifdef DDB
475    char *newfilename;
476#endif
477
478    ef = (elf_file_t) lf;
479#if 0	/* this will be more trouble than it's worth for now */
480    for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
481	if (dp->d_tag != DT_NEEDED)
482	    continue;
483	modname = ef->strtab + dp->d_un.d_val;
484	error = linker_load_module(modname, lf);
485	if (error)
486	    goto out;
487    }
488#endif
489    error = relocate_file(ef);
490    if (error)
491	return error;
492    (void)link_elf_preload_parse_symbols(ef);
493
494#ifdef DDB
495    GDB_STATE(RT_ADD);
496    ef->gdb.l_addr = lf->address;
497    newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
498    strcpy(newfilename, lf->filename);
499    ef->gdb.l_name = newfilename;
500    ef->gdb.l_ld = ef->dynamic;
501    link_elf_add_gdb(&ef->gdb);
502    GDB_STATE(RT_CONSISTENT);
503#endif
504
505    return (0);
506}
507
508static int
509link_elf_load_file(linker_class_t cls, const char* filename, linker_file_t* result)
510{
511    struct nameidata nd;
512    struct thread* td = curthread;	/* XXX */
513    struct proc* p = td->td_proc;	/* XXX */
514    Elf_Ehdr *hdr;
515    caddr_t firstpage;
516    int nbytes, i;
517    Elf_Phdr *phdr;
518    Elf_Phdr *phlimit;
519    Elf_Phdr *segs[2];
520    int nsegs;
521    Elf_Phdr *phdyn;
522    Elf_Phdr *phphdr;
523    caddr_t mapbase;
524    size_t mapsize;
525    Elf_Off base_offset;
526    Elf_Addr base_vaddr;
527    Elf_Addr base_vlimit;
528    int error = 0;
529    int resid, flags;
530    elf_file_t ef;
531    linker_file_t lf;
532    Elf_Shdr *shdr;
533    int symtabindex;
534    int symstrindex;
535    int symcnt;
536    int strcnt;
537#ifdef DDB
538    char *newfilename;
539#endif
540
541    GIANT_REQUIRED;
542
543    shdr = NULL;
544    lf = NULL;
545
546    NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
547    flags = FREAD;
548    error = vn_open(&nd, &flags, 0);
549    if (error)
550	return error;
551    NDFREE(&nd, NDF_ONLY_PNBUF);
552
553    /*
554     * Read the elf header from the file.
555     */
556    firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
557    if (firstpage == NULL) {
558	error = ENOMEM;
559	goto out;
560    }
561    hdr = (Elf_Ehdr *)firstpage;
562    error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
563		    UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td);
564    nbytes = PAGE_SIZE - resid;
565    if (error)
566	goto out;
567
568    if (!IS_ELF(*hdr)) {
569	error = ENOEXEC;
570	goto out;
571    }
572
573    if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS
574      || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
575	link_elf_error("Unsupported file layout");
576	error = ENOEXEC;
577	goto out;
578    }
579    if (hdr->e_ident[EI_VERSION] != EV_CURRENT
580      || hdr->e_version != EV_CURRENT) {
581	link_elf_error("Unsupported file version");
582	error = ENOEXEC;
583	goto out;
584    }
585    if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
586	link_elf_error("Unsupported file type");
587	error = ENOEXEC;
588	goto out;
589    }
590    if (hdr->e_machine != ELF_TARG_MACH) {
591	link_elf_error("Unsupported machine");
592	error = ENOEXEC;
593	goto out;
594    }
595
596    /*
597     * We rely on the program header being in the first page.  This is
598     * not strictly required by the ABI specification, but it seems to
599     * always true in practice.  And, it simplifies things considerably.
600     */
601    if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
602	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
603	  (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
604	link_elf_error("Unreadable program headers");
605
606    /*
607     * Scan the program header entries, and save key information.
608     *
609     * We rely on there being exactly two load segments, text and data,
610     * in that order.
611     */
612    phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
613    phlimit = phdr + hdr->e_phnum;
614    nsegs = 0;
615    phdyn = NULL;
616    phphdr = NULL;
617    while (phdr < phlimit) {
618	switch (phdr->p_type) {
619
620	case PT_LOAD:
621	    if (nsegs == 2) {
622		link_elf_error("Too many sections");
623		error = ENOEXEC;
624		goto out;
625	    }
626	    segs[nsegs] = phdr;
627	    ++nsegs;
628	    break;
629
630	case PT_PHDR:
631	    phphdr = phdr;
632	    break;
633
634	case PT_DYNAMIC:
635	    phdyn = phdr;
636	    break;
637
638	case PT_INTERP:
639	    link_elf_error("Unsupported file type");
640	    error = ENOEXEC;
641	    goto out;
642	}
643
644	++phdr;
645    }
646    if (phdyn == NULL) {
647	link_elf_error("Object is not dynamically-linked");
648	error = ENOEXEC;
649	goto out;
650    }
651
652    /*
653     * Allocate the entire address space of the object, to stake out our
654     * contiguous region, and to establish the base address for relocation.
655     */
656    base_offset = trunc_page(segs[0]->p_offset);
657    base_vaddr = trunc_page(segs[0]->p_vaddr);
658    base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
659    mapsize = base_vlimit - base_vaddr;
660
661    lf = linker_make_file(filename, &link_elf_class);
662    if (!lf) {
663	error = ENOMEM;
664	goto out;
665    }
666
667    ef = (elf_file_t) lf;
668#ifdef SPARSE_MAPPING
669    ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
670    if (ef->object == NULL) {
671	free(ef, M_LINKER);
672	error = ENOMEM;
673	goto out;
674    }
675    vm_object_reference(ef->object);
676    ef->address = (caddr_t) vm_map_min(kernel_map);
677    error = vm_map_find(kernel_map, ef->object, 0,
678			(vm_offset_t *) &ef->address,
679			mapsize, 1,
680			VM_PROT_ALL, VM_PROT_ALL, 0);
681    if (error) {
682	vm_object_deallocate(ef->object);
683	ef->object = 0;
684	goto out;
685    }
686#else
687    ef->address = malloc(mapsize, M_LINKER, M_WAITOK);
688    if (!ef->address) {
689	error = ENOMEM;
690	goto out;
691    }
692#endif
693    mapbase = ef->address;
694
695    /*
696     * Read the text and data sections and zero the bss.
697     */
698    for (i = 0; i < 2; i++) {
699	caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
700	error = vn_rdwr(UIO_READ, nd.ni_vp,
701			segbase, segs[i]->p_filesz, segs[i]->p_offset,
702			UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, td);
703	if (error) {
704	    goto out;
705	}
706	bzero(segbase + segs[i]->p_filesz,
707	      segs[i]->p_memsz - segs[i]->p_filesz);
708
709#ifdef SPARSE_MAPPING
710	/*
711	 * Wire down the pages
712	 */
713	vm_map_pageable(kernel_map,
714			(vm_offset_t) segbase,
715			(vm_offset_t) segbase + segs[i]->p_memsz,
716			FALSE);
717#endif
718    }
719
720#ifdef GPROF
721    /* Update profiling information with the new text segment. */
722    kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
723	segs[0]->p_memsz));
724#endif
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, td);
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, td);
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, td);
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, td);
824    vn_close(nd.ni_vp, FREAD, p->p_ucred, td);
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 *)(uintptr_t)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