2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 1998-2000 Doug Rabson
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
35 #include <sys/param.h>
36 #include <sys/systm.h>
40 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/mutex.h>
44 #include <sys/mount.h>
47 #include <sys/namei.h>
48 #include <sys/fcntl.h>
49 #include <sys/vnode.h>
50 #include <sys/linker.h>
52 #include <machine/elf.h>
56 #include <security/mac/mac_framework.h>
59 #include <vm/vm_param.h>
61 #include <vm/vm_object.h>
62 #include <vm/vm_kern.h>
63 #include <vm/vm_extern.h>
66 #include <vm/vm_map.h>
68 #include <sys/link_elf.h>
70 #include "linker_if.h"
74 typedef struct elf_file {
75 struct linker_file lf; /* Common fields */
76 int preloaded; /* Was file pre-loaded */
77 caddr_t address; /* Relocation address */
79 vm_object_t object; /* VM object to hold file pages */
81 Elf_Dyn *dynamic; /* Symbol table etc. */
82 Elf_Hashelt nbuckets; /* DT_HASH info */
84 const Elf_Hashelt *buckets;
85 const Elf_Hashelt *chains;
87 caddr_t strtab; /* DT_STRTAB */
88 int strsz; /* DT_STRSZ */
89 const Elf_Sym *symtab; /* DT_SYMTAB */
90 Elf_Addr *got; /* DT_PLTGOT */
91 const Elf_Rel *pltrel; /* DT_JMPREL */
92 int pltrelsize; /* DT_PLTRELSZ */
93 const Elf_Rela *pltrela; /* DT_JMPREL */
94 int pltrelasize; /* DT_PLTRELSZ */
95 const Elf_Rel *rel; /* DT_REL */
96 int relsize; /* DT_RELSZ */
97 const Elf_Rela *rela; /* DT_RELA */
98 int relasize; /* DT_RELASZ */
100 const Elf_Sym *ddbsymtab; /* The symbol table we are using */
101 long ddbsymcnt; /* Number of symbols */
102 caddr_t ddbstrtab; /* String table */
103 long ddbstrcnt; /* number of bytes in string table */
104 caddr_t symbase; /* malloc'ed symbold base */
105 caddr_t strbase; /* malloc'ed string base */
106 caddr_t ctftab; /* CTF table */
107 long ctfcnt; /* number of bytes in CTF table */
108 caddr_t ctfoff; /* CTF offset table */
109 caddr_t typoff; /* Type offset table */
110 long typlen; /* Number of type entries. */
111 Elf_Addr pcpu_start; /* Pre-relocation pcpu set start. */
112 Elf_Addr pcpu_stop; /* Pre-relocation pcpu set stop. */
113 Elf_Addr pcpu_base; /* Relocated pcpu set address. */
115 Elf_Addr vnet_start; /* Pre-relocation vnet set start. */
116 Elf_Addr vnet_stop; /* Pre-relocation vnet set stop. */
117 Elf_Addr vnet_base; /* Relocated vnet set address. */
120 struct link_map gdb; /* hooks for gdb */
128 TAILQ_ENTRY(elf_set) es_link;
131 TAILQ_HEAD(elf_set_head, elf_set);
133 #include <kern/kern_ctf.c>
135 static int link_elf_link_common_finish(linker_file_t);
136 static int link_elf_link_preload(linker_class_t cls,
137 const char *, linker_file_t *);
138 static int link_elf_link_preload_finish(linker_file_t);
139 static int link_elf_load_file(linker_class_t, const char *,
141 static int link_elf_lookup_symbol(linker_file_t, const char *,
143 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t,
145 static int link_elf_search_symbol(linker_file_t, caddr_t,
146 c_linker_sym_t *, long *);
148 static void link_elf_unload_file(linker_file_t);
149 static void link_elf_unload_preload(linker_file_t);
150 static int link_elf_lookup_set(linker_file_t, const char *,
151 void ***, void ***, int *);
152 static int link_elf_each_function_name(linker_file_t,
153 int (*)(const char *, void *), void *);
154 static int link_elf_each_function_nameval(linker_file_t,
155 linker_function_nameval_callback_t, void *);
156 static void link_elf_reloc_local(linker_file_t);
157 static long link_elf_symtab_get(linker_file_t, const Elf_Sym **);
158 static long link_elf_strtab_get(linker_file_t, caddr_t *);
159 static int elf_lookup(linker_file_t, Elf_Size, int, Elf_Addr *);
161 static kobj_method_t link_elf_methods[] = {
162 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
163 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
164 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
165 KOBJMETHOD(linker_unload, link_elf_unload_file),
166 KOBJMETHOD(linker_load_file, link_elf_load_file),
167 KOBJMETHOD(linker_link_preload, link_elf_link_preload),
168 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
169 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set),
170 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
171 KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
172 KOBJMETHOD(linker_ctf_get, link_elf_ctf_get),
173 KOBJMETHOD(linker_symtab_get, link_elf_symtab_get),
174 KOBJMETHOD(linker_strtab_get, link_elf_strtab_get),
178 static struct linker_class link_elf_class = {
179 #if ELF_TARG_CLASS == ELFCLASS32
184 link_elf_methods, sizeof(struct elf_file)
187 typedef int (*elf_reloc_fn)(linker_file_t lf, Elf_Addr relocbase,
188 const void *data, int type, elf_lookup_fn lookup);
190 static int parse_dynamic(elf_file_t);
191 static int relocate_file(elf_file_t);
192 static int relocate_file1(elf_file_t ef, elf_lookup_fn lookup,
193 elf_reloc_fn reloc, bool ifuncs);
194 static int link_elf_preload_parse_symbols(elf_file_t);
196 static struct elf_set_head set_pcpu_list;
198 static struct elf_set_head set_vnet_list;
202 elf_set_add(struct elf_set_head *list, Elf_Addr start, Elf_Addr stop, Elf_Addr base)
204 struct elf_set *set, *iter;
206 set = malloc(sizeof(*set), M_LINKER, M_WAITOK);
207 set->es_start = start;
211 TAILQ_FOREACH(iter, list, es_link) {
213 KASSERT((set->es_start < iter->es_start && set->es_stop < iter->es_stop) ||
214 (set->es_start > iter->es_start && set->es_stop > iter->es_stop),
215 ("linker sets intersection: to insert: 0x%jx-0x%jx; inserted: 0x%jx-0x%jx",
216 (uintmax_t)set->es_start, (uintmax_t)set->es_stop,
217 (uintmax_t)iter->es_start, (uintmax_t)iter->es_stop));
219 if (iter->es_start > set->es_start) {
220 TAILQ_INSERT_BEFORE(iter, set, es_link);
226 TAILQ_INSERT_TAIL(list, set, es_link);
230 elf_set_find(struct elf_set_head *list, Elf_Addr addr, Elf_Addr *start, Elf_Addr *base)
234 TAILQ_FOREACH(set, list, es_link) {
235 if (addr < set->es_start)
237 if (addr < set->es_stop) {
238 *start = set->es_start;
239 *base = set->es_base;
248 elf_set_delete(struct elf_set_head *list, Elf_Addr start)
252 TAILQ_FOREACH(set, list, es_link) {
253 if (start < set->es_start)
255 if (start == set->es_start) {
256 TAILQ_REMOVE(list, set, es_link);
261 KASSERT(0, ("deleting unknown linker set (start = 0x%jx)",
266 static void r_debug_state(struct r_debug *, struct link_map *);
269 * A list of loaded modules for GDB to use for loading symbols.
271 struct r_debug r_debug;
273 #define GDB_STATE(s) do { \
274 r_debug.r_state = s; r_debug_state(NULL, NULL); \
278 * Function for the debugger to set a breakpoint on to gain control.
281 r_debug_state(struct r_debug *dummy_one __unused,
282 struct link_map *dummy_two __unused)
287 link_elf_add_gdb(struct link_map *l)
289 struct link_map *prev;
293 if (r_debug.r_map == NULL) {
298 /* Append to list. */
299 for (prev = r_debug.r_map;
300 prev->l_next != NULL;
309 link_elf_delete_gdb(struct link_map *l)
311 if (l->l_prev == NULL) {
313 if ((r_debug.r_map = l->l_next) != NULL)
314 l->l_next->l_prev = NULL;
316 /* Remove any but first. */
317 if ((l->l_prev->l_next = l->l_next) != NULL)
318 l->l_next->l_prev = l->l_prev;
324 * The kernel symbol table starts here.
326 extern struct _dynamic _DYNAMIC;
329 link_elf_error(const char *filename, const char *s)
331 if (filename == NULL)
332 printf("kldload: %s\n", s);
334 printf("kldload: %s: %s\n", filename, s);
338 link_elf_invoke_ctors(caddr_t addr, size_t size)
343 if (addr == NULL || size == 0)
345 cnt = size / sizeof(*ctor);
347 for (i = 0; i < cnt; i++) {
354 * Actions performed after linking/loading both the preloaded kernel and any
355 * modules; whether preloaded or dynamicly loaded.
358 link_elf_link_common_finish(linker_file_t lf)
361 elf_file_t ef = (elf_file_t)lf;
366 /* Notify MD code that a module is being loaded. */
367 error = elf_cpu_load_file(lf);
373 ef->gdb.l_addr = lf->address;
374 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
375 strcpy(newfilename, lf->filename);
376 ef->gdb.l_name = newfilename;
377 ef->gdb.l_ld = ef->dynamic;
378 link_elf_add_gdb(&ef->gdb);
379 GDB_STATE(RT_CONSISTENT);
383 link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
387 extern vm_offset_t __startkernel, __endkernel;
390 link_elf_init(void* arg)
393 Elf_Addr *ctors_addrp;
394 Elf_Size *ctors_sizep;
395 caddr_t modptr, baseptr, sizeptr;
399 linker_add_class(&link_elf_class);
401 dp = (Elf_Dyn *)&_DYNAMIC;
403 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
405 modptr = preload_search_by_type("elf kernel");
406 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
409 linker_kernel_file = linker_make_file(modname, &link_elf_class);
410 if (linker_kernel_file == NULL)
411 panic("%s: Can't create linker structures for kernel",
414 ef = (elf_file_t) linker_kernel_file;
417 ef->address = (caddr_t) (__startkernel - KERNBASE);
421 #ifdef SPARSE_MAPPING
429 linker_kernel_file->address = (caddr_t)__startkernel;
430 linker_kernel_file->size = (intptr_t)(__endkernel - __startkernel);
432 linker_kernel_file->address += KERNBASE;
433 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
436 if (modptr != NULL) {
438 baseptr = preload_search_info(modptr, MODINFO_ADDR);
440 linker_kernel_file->address = *(caddr_t *)baseptr;
441 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
443 linker_kernel_file->size = *(size_t *)sizeptr;
444 ctors_addrp = (Elf_Addr *)preload_search_info(modptr,
445 MODINFO_METADATA | MODINFOMD_CTORS_ADDR);
446 ctors_sizep = (Elf_Size *)preload_search_info(modptr,
447 MODINFO_METADATA | MODINFOMD_CTORS_SIZE);
448 if (ctors_addrp != NULL && ctors_sizep != NULL) {
449 linker_kernel_file->ctors_addr = ef->address +
451 linker_kernel_file->ctors_size = *ctors_sizep;
454 (void)link_elf_preload_parse_symbols(ef);
457 r_debug.r_map = NULL;
458 r_debug.r_brk = r_debug_state;
459 r_debug.r_state = RT_CONSISTENT;
462 (void)link_elf_link_common_finish(linker_kernel_file);
463 linker_kernel_file->flags |= LINKER_FILE_LINKED;
464 TAILQ_INIT(&set_pcpu_list);
466 TAILQ_INIT(&set_vnet_list);
470 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, NULL);
473 link_elf_preload_parse_symbols(elf_file_t ef)
476 caddr_t ssym, esym, base;
482 if (ef->modptr == NULL)
484 pointer = preload_search_info(ef->modptr,
485 MODINFO_METADATA | MODINFOMD_SSYM);
488 ssym = *(caddr_t *)pointer;
489 pointer = preload_search_info(ef->modptr,
490 MODINFO_METADATA | MODINFOMD_ESYM);
493 esym = *(caddr_t *)pointer;
497 symcnt = *(long *)base;
498 base += sizeof(long);
499 symtab = (Elf_Sym *)base;
500 base += roundup(symcnt, sizeof(long));
502 if (base > esym || base < ssym) {
503 printf("Symbols are corrupt!\n");
507 strcnt = *(long *)base;
508 base += sizeof(long);
510 base += roundup(strcnt, sizeof(long));
512 if (base > esym || base < ssym) {
513 printf("Symbols are corrupt!\n");
517 ef->ddbsymtab = symtab;
518 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
519 ef->ddbstrtab = strtab;
520 ef->ddbstrcnt = strcnt;
526 parse_dynamic(elf_file_t ef)
529 int plttype = DT_REL;
531 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
535 /* From src/libexec/rtld-elf/rtld.c */
536 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
537 (ef->address + dp->d_un.d_ptr);
538 ef->nbuckets = hashtab[0];
539 ef->nchains = hashtab[1];
540 ef->buckets = hashtab + 2;
541 ef->chains = ef->buckets + ef->nbuckets;
545 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
548 ef->strsz = dp->d_un.d_val;
551 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
554 if (dp->d_un.d_val != sizeof(Elf_Sym))
558 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
561 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
564 ef->relsize = dp->d_un.d_val;
567 if (dp->d_un.d_val != sizeof(Elf_Rel))
571 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
574 ef->pltrelsize = dp->d_un.d_val;
577 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
580 ef->relasize = dp->d_un.d_val;
583 if (dp->d_un.d_val != sizeof(Elf_Rela))
587 plttype = dp->d_un.d_val;
588 if (plttype != DT_REL && plttype != DT_RELA)
593 dp->d_un.d_ptr = (Elf_Addr)&r_debug;
599 if (plttype == DT_RELA) {
600 ef->pltrela = (const Elf_Rela *)ef->pltrel;
602 ef->pltrelasize = ef->pltrelsize;
606 ef->ddbsymtab = ef->symtab;
607 ef->ddbsymcnt = ef->nchains;
608 ef->ddbstrtab = ef->strtab;
609 ef->ddbstrcnt = ef->strsz;
614 #define LS_PADDING 0x90909090
616 parse_dpcpu(elf_file_t ef)
619 #if defined(__i386__)
625 error = link_elf_lookup_set(&ef->lf, "pcpu", (void ***)&ef->pcpu_start,
626 (void ***)&ef->pcpu_stop, NULL);
627 /* Error just means there is no pcpu set to relocate. */
630 size = (uintptr_t)ef->pcpu_stop - (uintptr_t)ef->pcpu_start;
634 #if defined(__i386__)
635 /* In case we do find __start/stop_set_ symbols double-check. */
637 uprintf("Kernel module '%s' must be recompiled with "
638 "linker script\n", ef->lf.pathname);
642 /* Padding from linker-script correct? */
643 pad = *(uint32_t *)((uintptr_t)ef->pcpu_stop - sizeof(pad));
644 if (pad != LS_PADDING) {
645 uprintf("Kernel module '%s' must be recompiled with "
646 "linker script, invalid padding %#04x (%#04x)\n",
647 ef->lf.pathname, pad, LS_PADDING);
650 /* If we only have valid padding, nothing to do. */
655 * Allocate space in the primary pcpu area. Copy in our
656 * initialization from the data section and then initialize
657 * all per-cpu storage from that.
659 ef->pcpu_base = (Elf_Addr)(uintptr_t)dpcpu_alloc(size);
660 if (ef->pcpu_base == 0) {
661 printf("%s: pcpu module space is out of space; "
662 "cannot allocate %d for %s\n",
663 __func__, size, ef->lf.pathname);
666 memcpy((void *)ef->pcpu_base, (void *)ef->pcpu_start, size);
667 dpcpu_copy((void *)ef->pcpu_base, size);
668 elf_set_add(&set_pcpu_list, ef->pcpu_start, ef->pcpu_stop,
676 parse_vnet(elf_file_t ef)
679 #if defined(__i386__)
685 error = link_elf_lookup_set(&ef->lf, "vnet", (void ***)&ef->vnet_start,
686 (void ***)&ef->vnet_stop, NULL);
687 /* Error just means there is no vnet data set to relocate. */
690 size = (uintptr_t)ef->vnet_stop - (uintptr_t)ef->vnet_start;
694 #if defined(__i386__)
695 /* In case we do find __start/stop_set_ symbols double-check. */
697 uprintf("Kernel module '%s' must be recompiled with "
698 "linker script\n", ef->lf.pathname);
702 /* Padding from linker-script correct? */
703 pad = *(uint32_t *)((uintptr_t)ef->vnet_stop - sizeof(pad));
704 if (pad != LS_PADDING) {
705 uprintf("Kernel module '%s' must be recompiled with "
706 "linker script, invalid padding %#04x (%#04x)\n",
707 ef->lf.pathname, pad, LS_PADDING);
710 /* If we only have valid padding, nothing to do. */
715 * Allocate space in the primary vnet area. Copy in our
716 * initialization from the data section and then initialize
717 * all per-vnet storage from that.
719 ef->vnet_base = (Elf_Addr)(uintptr_t)vnet_data_alloc(size);
720 if (ef->vnet_base == 0) {
721 printf("%s: vnet module space is out of space; "
722 "cannot allocate %d for %s\n",
723 __func__, size, ef->lf.pathname);
726 memcpy((void *)ef->vnet_base, (void *)ef->vnet_start, size);
727 vnet_data_copy((void *)ef->vnet_base, size);
728 elf_set_add(&set_vnet_list, ef->vnet_start, ef->vnet_stop,
737 link_elf_link_preload(linker_class_t cls,
738 const char* filename, linker_file_t *result)
740 Elf_Addr *ctors_addrp;
741 Elf_Size *ctors_sizep;
742 caddr_t modptr, baseptr, sizeptr, dynptr;
749 /* Look to see if we have the file preloaded */
750 modptr = preload_search_by_name(filename);
754 type = (char *)preload_search_info(modptr, MODINFO_TYPE);
755 baseptr = preload_search_info(modptr, MODINFO_ADDR);
756 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
757 dynptr = preload_search_info(modptr,
758 MODINFO_METADATA | MODINFOMD_DYNAMIC);
760 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
761 strcmp(type, "elf module") != 0))
763 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
766 lf = linker_make_file(filename, &link_elf_class);
770 ef = (elf_file_t) lf;
773 ef->address = *(caddr_t *)baseptr;
774 #ifdef SPARSE_MAPPING
777 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
778 ef->dynamic = (Elf_Dyn *)dp;
779 lf->address = ef->address;
780 lf->size = *(size_t *)sizeptr;
782 ctors_addrp = (Elf_Addr *)preload_search_info(modptr,
783 MODINFO_METADATA | MODINFOMD_CTORS_ADDR);
784 ctors_sizep = (Elf_Size *)preload_search_info(modptr,
785 MODINFO_METADATA | MODINFOMD_CTORS_SIZE);
786 if (ctors_addrp != NULL && ctors_sizep != NULL) {
787 lf->ctors_addr = ef->address + *ctors_addrp;
788 lf->ctors_size = *ctors_sizep;
791 error = parse_dynamic(ef);
793 error = parse_dpcpu(ef);
796 error = parse_vnet(ef);
799 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
802 link_elf_reloc_local(lf);
808 link_elf_link_preload_finish(linker_file_t lf)
813 ef = (elf_file_t) lf;
814 error = relocate_file(ef);
817 (void)link_elf_preload_parse_symbols(ef);
819 return (link_elf_link_common_finish(lf));
823 link_elf_load_file(linker_class_t cls, const char* filename,
824 linker_file_t* result)
827 struct thread* td = curthread; /* XXX */
833 Elf_Phdr *segs[MAXSEGS];
839 Elf_Addr base_vlimit;
857 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
859 error = vn_open(&nd, &flags, 0, NULL);
862 NDFREE(&nd, NDF_ONLY_PNBUF);
863 if (nd.ni_vp->v_type != VREG) {
869 error = mac_kld_check_load(curthread->td_ucred, nd.ni_vp);
877 * Read the elf header from the file.
879 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
880 hdr = (Elf_Ehdr *)firstpage;
881 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
882 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
884 nbytes = PAGE_SIZE - resid;
893 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
894 hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
895 link_elf_error(filename, "Unsupported file layout");
899 if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
900 hdr->e_version != EV_CURRENT) {
901 link_elf_error(filename, "Unsupported file version");
905 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
909 if (hdr->e_machine != ELF_TARG_MACH) {
910 link_elf_error(filename, "Unsupported machine");
916 * We rely on the program header being in the first page.
917 * This is not strictly required by the ABI specification, but
918 * it seems to always true in practice. And, it simplifies
919 * things considerably.
921 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
922 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
923 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
924 link_elf_error(filename, "Unreadable program headers");
927 * Scan the program header entries, and save key information.
929 * We rely on there being exactly two load segments, text and data,
932 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
933 phlimit = phdr + hdr->e_phnum;
936 while (phdr < phlimit) {
937 switch (phdr->p_type) {
939 if (nsegs == MAXSEGS) {
940 link_elf_error(filename, "Too many sections");
945 * XXX: We just trust they come in right order ??
963 link_elf_error(filename, "Object is not dynamically-linked");
968 link_elf_error(filename, "No sections");
974 * Allocate the entire address space of the object, to stake
975 * out our contiguous region, and to establish the base
976 * address for relocation.
978 base_vaddr = trunc_page(segs[0]->p_vaddr);
979 base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
980 segs[nsegs - 1]->p_memsz);
981 mapsize = base_vlimit - base_vaddr;
983 lf = linker_make_file(filename, &link_elf_class);
989 ef = (elf_file_t) lf;
990 #ifdef SPARSE_MAPPING
991 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
992 if (ef->object == NULL) {
996 ef->address = (caddr_t) vm_map_min(kernel_map);
997 error = vm_map_find(kernel_map, ef->object, 0,
998 (vm_offset_t *) &ef->address, mapsize, 0, VMFS_OPTIMAL_SPACE,
999 VM_PROT_ALL, VM_PROT_ALL, 0);
1001 vm_object_deallocate(ef->object);
1006 ef->address = malloc(mapsize, M_LINKER, M_EXEC | M_WAITOK);
1008 mapbase = ef->address;
1011 * Read the text and data sections and zero the bss.
1013 for (i = 0; i < nsegs; i++) {
1014 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
1015 error = vn_rdwr(UIO_READ, nd.ni_vp,
1016 segbase, segs[i]->p_filesz, segs[i]->p_offset,
1017 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1021 bzero(segbase + segs[i]->p_filesz,
1022 segs[i]->p_memsz - segs[i]->p_filesz);
1024 #ifdef SPARSE_MAPPING
1026 * Wire down the pages
1028 error = vm_map_wire(kernel_map,
1029 (vm_offset_t) segbase,
1030 (vm_offset_t) segbase + segs[i]->p_memsz,
1031 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
1032 if (error != KERN_SUCCESS) {
1040 /* Update profiling information with the new text segment. */
1042 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
1047 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
1049 lf->address = ef->address;
1052 error = parse_dynamic(ef);
1055 error = parse_dpcpu(ef);
1059 error = parse_vnet(ef);
1063 link_elf_reloc_local(lf);
1065 VOP_UNLOCK(nd.ni_vp, 0);
1066 error = linker_load_dependencies(lf);
1067 vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
1070 error = relocate_file(ef);
1075 * Try and load the symbol table if it's present. (you can
1078 nbytes = hdr->e_shnum * hdr->e_shentsize;
1079 if (nbytes == 0 || hdr->e_shoff == 0)
1081 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
1082 error = vn_rdwr(UIO_READ, nd.ni_vp,
1083 (caddr_t)shdr, nbytes, hdr->e_shoff,
1084 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1089 /* Read section string table */
1090 shstrindex = hdr->e_shstrndx;
1091 if (shstrindex != 0 && shdr[shstrindex].sh_type == SHT_STRTAB &&
1092 shdr[shstrindex].sh_size != 0) {
1093 nbytes = shdr[shstrindex].sh_size;
1094 shstrs = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
1095 error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shstrs, nbytes,
1096 shdr[shstrindex].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
1097 td->td_ucred, NOCRED, &resid, td);
1104 for (i = 0; i < hdr->e_shnum; i++) {
1105 if (shdr[i].sh_type == SHT_SYMTAB) {
1107 symstrindex = shdr[i].sh_link;
1108 } else if (shstrs != NULL && shdr[i].sh_name != 0 &&
1109 strcmp(shstrs + shdr[i].sh_name, ".ctors") == 0) {
1110 /* Record relocated address and size of .ctors. */
1111 lf->ctors_addr = mapbase + shdr[i].sh_addr - base_vaddr;
1112 lf->ctors_size = shdr[i].sh_size;
1115 if (symtabindex < 0 || symstrindex < 0)
1118 symcnt = shdr[symtabindex].sh_size;
1119 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
1120 strcnt = shdr[symstrindex].sh_size;
1121 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
1123 error = vn_rdwr(UIO_READ, nd.ni_vp,
1124 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
1125 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1129 error = vn_rdwr(UIO_READ, nd.ni_vp,
1130 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
1131 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1136 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
1137 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
1138 ef->ddbstrcnt = strcnt;
1139 ef->ddbstrtab = ef->strbase;
1142 error = link_elf_link_common_finish(lf);
1149 VOP_UNLOCK(nd.ni_vp, 0);
1150 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
1151 if (error != 0 && lf != NULL)
1152 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
1153 free(shdr, M_LINKER);
1154 free(firstpage, M_LINKER);
1155 free(shstrs, M_LINKER);
1161 elf_relocaddr(linker_file_t lf, Elf_Addr x)
1165 ef = (elf_file_t)lf;
1166 if (x >= ef->pcpu_start && x < ef->pcpu_stop)
1167 return ((x - ef->pcpu_start) + ef->pcpu_base);
1169 if (x >= ef->vnet_start && x < ef->vnet_stop)
1170 return ((x - ef->vnet_start) + ef->vnet_base);
1177 link_elf_unload_file(linker_file_t file)
1179 elf_file_t ef = (elf_file_t) file;
1181 if (ef->pcpu_base != 0) {
1182 dpcpu_free((void *)ef->pcpu_base,
1183 ef->pcpu_stop - ef->pcpu_start);
1184 elf_set_delete(&set_pcpu_list, ef->pcpu_start);
1187 if (ef->vnet_base != 0) {
1188 vnet_data_free((void *)ef->vnet_base,
1189 ef->vnet_stop - ef->vnet_start);
1190 elf_set_delete(&set_vnet_list, ef->vnet_start);
1194 if (ef->gdb.l_ld != NULL) {
1195 GDB_STATE(RT_DELETE);
1196 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
1197 link_elf_delete_gdb(&ef->gdb);
1198 GDB_STATE(RT_CONSISTENT);
1202 /* Notify MD code that a module is being unloaded. */
1203 elf_cpu_unload_file(file);
1205 if (ef->preloaded) {
1206 link_elf_unload_preload(file);
1210 #ifdef SPARSE_MAPPING
1211 if (ef->object != NULL) {
1212 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
1213 (vm_offset_t) ef->address
1214 + (ef->object->size << PAGE_SHIFT));
1217 free(ef->address, M_LINKER);
1219 free(ef->symbase, M_LINKER);
1220 free(ef->strbase, M_LINKER);
1221 free(ef->ctftab, M_LINKER);
1222 free(ef->ctfoff, M_LINKER);
1223 free(ef->typoff, M_LINKER);
1227 link_elf_unload_preload(linker_file_t file)
1229 if (file->pathname != NULL)
1230 preload_delete_name(file->pathname);
1234 symbol_name(elf_file_t ef, Elf_Size r_info)
1238 if (ELF_R_SYM(r_info)) {
1239 ref = ef->symtab + ELF_R_SYM(r_info);
1240 return (ef->strtab + ref->st_name);
1246 symbol_type(elf_file_t ef, Elf_Size r_info)
1250 if (ELF_R_SYM(r_info)) {
1251 ref = ef->symtab + ELF_R_SYM(r_info);
1252 return (ELF_ST_TYPE(ref->st_info));
1254 return (STT_NOTYPE);
1258 relocate_file1(elf_file_t ef, elf_lookup_fn lookup, elf_reloc_fn reloc,
1262 const Elf_Rela *rela;
1263 const char *symname;
1265 #define APPLY_RELOCS(iter, tbl, tblsize, type) do { \
1266 for ((iter) = (tbl); (iter) != NULL && \
1267 (iter) < (tbl) + (tblsize) / sizeof(*(iter)); (iter)++) { \
1268 if ((symbol_type(ef, (iter)->r_info) == \
1270 elf_is_ifunc_reloc((iter)->r_info)) != ifuncs) \
1272 if (reloc(&ef->lf, (Elf_Addr)ef->address, \
1273 (iter), (type), lookup)) { \
1274 symname = symbol_name(ef, (iter)->r_info); \
1275 printf("link_elf: symbol %s undefined\n", \
1282 APPLY_RELOCS(rel, ef->rel, ef->relsize, ELF_RELOC_REL);
1283 APPLY_RELOCS(rela, ef->rela, ef->relasize, ELF_RELOC_RELA);
1284 APPLY_RELOCS(rel, ef->pltrel, ef->pltrelsize, ELF_RELOC_REL);
1285 APPLY_RELOCS(rela, ef->pltrela, ef->pltrelasize, ELF_RELOC_RELA);
1293 relocate_file(elf_file_t ef)
1297 error = relocate_file1(ef, elf_lookup, elf_reloc, false);
1299 error = relocate_file1(ef, elf_lookup, elf_reloc, true);
1304 * Hash function for symbol table lookup. Don't even think about changing
1305 * this. It is specified by the System V ABI.
1307 static unsigned long
1308 elf_hash(const char *name)
1310 const unsigned char *p = (const unsigned char *) name;
1311 unsigned long h = 0;
1314 while (*p != '\0') {
1315 h = (h << 4) + *p++;
1316 if ((g = h & 0xf0000000) != 0)
1324 link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
1326 elf_file_t ef = (elf_file_t) lf;
1327 unsigned long symnum;
1328 const Elf_Sym* symp;
1333 /* If we don't have a hash, bail. */
1334 if (ef->buckets == NULL || ef->nbuckets == 0) {
1335 printf("link_elf_lookup_symbol: missing symbol hash table\n");
1339 /* First, search hashed global symbols */
1340 hash = elf_hash(name);
1341 symnum = ef->buckets[hash % ef->nbuckets];
1343 while (symnum != STN_UNDEF) {
1344 if (symnum >= ef->nchains) {
1345 printf("%s: corrupt symbol table\n", __func__);
1349 symp = ef->symtab + symnum;
1350 if (symp->st_name == 0) {
1351 printf("%s: corrupt symbol table\n", __func__);
1355 strp = ef->strtab + symp->st_name;
1357 if (strcmp(name, strp) == 0) {
1358 if (symp->st_shndx != SHN_UNDEF ||
1359 (symp->st_value != 0 &&
1360 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1361 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC))) {
1362 *sym = (c_linker_sym_t) symp;
1368 symnum = ef->chains[symnum];
1371 /* If we have not found it, look at the full table (if loaded) */
1372 if (ef->symtab == ef->ddbsymtab)
1375 /* Exhaustive search */
1376 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1377 strp = ef->ddbstrtab + symp->st_name;
1378 if (strcmp(name, strp) == 0) {
1379 if (symp->st_shndx != SHN_UNDEF ||
1380 (symp->st_value != 0 &&
1381 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1382 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC))) {
1383 *sym = (c_linker_sym_t) symp;
1394 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
1395 linker_symval_t *symval)
1401 ef = (elf_file_t)lf;
1402 es = (const Elf_Sym *)sym;
1403 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1404 symval->name = ef->strtab + es->st_name;
1405 val = (caddr_t)ef->address + es->st_value;
1406 if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
1407 val = ((caddr_t (*)(void))val)();
1408 symval->value = val;
1409 symval->size = es->st_size;
1412 if (ef->symtab == ef->ddbsymtab)
1414 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1415 symval->name = ef->ddbstrtab + es->st_name;
1416 val = (caddr_t)ef->address + es->st_value;
1417 if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
1418 val = ((caddr_t (*)(void))val)();
1419 symval->value = val;
1420 symval->size = es->st_size;
1427 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1428 c_linker_sym_t *sym, long *diffp)
1430 elf_file_t ef = (elf_file_t) lf;
1431 u_long off = (uintptr_t) (void *) value;
1435 const Elf_Sym* best = NULL;
1438 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1439 if (es->st_name == 0)
1441 st_value = es->st_value + (uintptr_t) (void *) ef->address;
1442 if (off >= st_value) {
1443 if (off - st_value < diff) {
1444 diff = off - st_value;
1448 } else if (off - st_value == diff) {
1457 *sym = (c_linker_sym_t) best;
1463 * Look up a linker set on an ELF system.
1466 link_elf_lookup_set(linker_file_t lf, const char *name,
1467 void ***startp, void ***stopp, int *countp)
1470 linker_symval_t symval;
1472 void **start, **stop;
1473 int len, error = 0, count;
1475 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1476 setsym = malloc(len, M_LINKER, M_WAITOK);
1478 /* get address of first entry */
1479 snprintf(setsym, len, "%s%s", "__start_set_", name);
1480 error = link_elf_lookup_symbol(lf, setsym, &sym);
1483 link_elf_symbol_values(lf, sym, &symval);
1484 if (symval.value == 0) {
1488 start = (void **)symval.value;
1490 /* get address of last entry */
1491 snprintf(setsym, len, "%s%s", "__stop_set_", name);
1492 error = link_elf_lookup_symbol(lf, setsym, &sym);
1495 link_elf_symbol_values(lf, sym, &symval);
1496 if (symval.value == 0) {
1500 stop = (void **)symval.value;
1502 /* and the number of entries */
1503 count = stop - start;
1514 free(setsym, M_LINKER);
1519 link_elf_each_function_name(linker_file_t file,
1520 int (*callback)(const char *, void *), void *opaque)
1522 elf_file_t ef = (elf_file_t)file;
1523 const Elf_Sym *symp;
1526 /* Exhaustive search */
1527 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1528 if (symp->st_value != 0 &&
1529 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1530 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
1531 error = callback(ef->ddbstrtab + symp->st_name, opaque);
1540 link_elf_each_function_nameval(linker_file_t file,
1541 linker_function_nameval_callback_t callback, void *opaque)
1543 linker_symval_t symval;
1544 elf_file_t ef = (elf_file_t)file;
1545 const Elf_Sym* symp;
1548 /* Exhaustive search */
1549 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1550 if (symp->st_value != 0 &&
1551 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1552 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
1553 error = link_elf_symbol_values(file,
1554 (c_linker_sym_t) symp, &symval);
1557 error = callback(file, i, &symval, opaque);
1566 elf_get_sym(linker_file_t lf, Elf_Size symidx)
1568 elf_file_t ef = (elf_file_t)lf;
1570 if (symidx >= ef->nchains)
1572 return (ef->symtab + symidx);
1576 elf_get_symname(linker_file_t lf, Elf_Size symidx)
1578 elf_file_t ef = (elf_file_t)lf;
1581 if (symidx >= ef->nchains)
1583 sym = ef->symtab + symidx;
1584 return (ef->strtab + sym->st_name);
1588 * Symbol lookup function that can be used when the symbol index is known (ie
1589 * in relocations). It uses the symbol index instead of doing a fully fledged
1590 * hash table based lookup when such is valid. For example for local symbols.
1591 * This is not only more efficient, it's also more correct. It's not always
1592 * the case that the symbol can be found through the hash table.
1595 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *res)
1597 elf_file_t ef = (elf_file_t)lf;
1600 Elf_Addr addr, start, base;
1602 /* Don't even try to lookup the symbol if the index is bogus. */
1603 if (symidx >= ef->nchains) {
1608 sym = ef->symtab + symidx;
1611 * Don't do a full lookup when the symbol is local. It may even
1612 * fail because it may not be found through the hash table.
1614 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1615 /* Force lookup failure when we have an insanity. */
1616 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) {
1620 *res = ((Elf_Addr)ef->address + sym->st_value);
1625 * XXX we can avoid doing a hash table based lookup for global
1626 * symbols as well. This however is not always valid, so we'll
1627 * just do it the hard way for now. Performance tweaks can
1631 symbol = ef->strtab + sym->st_name;
1633 /* Force a lookup failure if the symbol name is bogus. */
1639 addr = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1640 if (addr == 0 && ELF_ST_BIND(sym->st_info) != STB_WEAK) {
1645 if (elf_set_find(&set_pcpu_list, addr, &start, &base))
1646 addr = addr - start + base;
1648 else if (elf_set_find(&set_vnet_list, addr, &start, &base))
1649 addr = addr - start + base;
1656 link_elf_reloc_local(linker_file_t lf)
1658 const Elf_Rel *rellim;
1660 const Elf_Rela *relalim;
1661 const Elf_Rela *rela;
1662 elf_file_t ef = (elf_file_t)lf;
1664 /* Perform relocations without addend if there are any: */
1665 if ((rel = ef->rel) != NULL) {
1666 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1667 while (rel < rellim) {
1668 elf_reloc_local(lf, (Elf_Addr)ef->address, rel,
1669 ELF_RELOC_REL, elf_lookup);
1674 /* Perform relocations with addend if there are any: */
1675 if ((rela = ef->rela) != NULL) {
1676 relalim = (const Elf_Rela *)
1677 ((const char *)ef->rela + ef->relasize);
1678 while (rela < relalim) {
1679 elf_reloc_local(lf, (Elf_Addr)ef->address, rela,
1680 ELF_RELOC_RELA, elf_lookup);
1687 link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
1689 elf_file_t ef = (elf_file_t)lf;
1691 *symtab = ef->ddbsymtab;
1693 if (*symtab == NULL)
1696 return (ef->ddbsymcnt);
1700 link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
1702 elf_file_t ef = (elf_file_t)lf;
1704 *strtab = ef->ddbstrtab;
1706 if (*strtab == NULL)
1709 return (ef->ddbstrcnt);
1712 #if defined(__i386__) || defined(__amd64__) || defined(__aarch64__)
1714 * Use this lookup routine when performing relocations early during boot.
1715 * The generic lookup routine depends on kobj, which is not initialized
1719 elf_lookup_ifunc(linker_file_t lf, Elf_Size symidx, int deps __unused,
1723 const Elf_Sym *symp;
1726 ef = (elf_file_t)lf;
1727 symp = ef->symtab + symidx;
1728 if (ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC) {
1729 val = (caddr_t)ef->address + symp->st_value;
1730 *res = ((Elf_Addr (*)(void))val)();
1737 link_elf_ireloc(caddr_t kmdp)
1739 struct elf_file eff;
1744 bzero_early(ef, sizeof(*ef));
1747 ef->dynamic = (Elf_Dyn *)&_DYNAMIC;
1750 link_elf_preload_parse_symbols(ef);
1751 relocate_file1(ef, elf_lookup_ifunc, elf_reloc, true);