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>
74 #include "linker_if.h"
78 typedef struct elf_file {
79 struct linker_file lf; /* Common fields */
80 int preloaded; /* Was file pre-loaded */
81 caddr_t address; /* Relocation address */
83 vm_object_t object; /* VM object to hold file pages */
85 Elf_Dyn *dynamic; /* Symbol table etc. */
86 Elf_Hashelt nbuckets; /* DT_HASH info */
88 const Elf_Hashelt *buckets;
89 const Elf_Hashelt *chains;
91 caddr_t strtab; /* DT_STRTAB */
92 int strsz; /* DT_STRSZ */
93 const Elf_Sym *symtab; /* DT_SYMTAB */
94 Elf_Addr *got; /* DT_PLTGOT */
95 const Elf_Rel *pltrel; /* DT_JMPREL */
96 int pltrelsize; /* DT_PLTRELSZ */
97 const Elf_Rela *pltrela; /* DT_JMPREL */
98 int pltrelasize; /* DT_PLTRELSZ */
99 const Elf_Rel *rel; /* DT_REL */
100 int relsize; /* DT_RELSZ */
101 const Elf_Rela *rela; /* DT_RELA */
102 int relasize; /* DT_RELASZ */
104 const Elf_Sym *ddbsymtab; /* The symbol table we are using */
105 long ddbsymcnt; /* Number of symbols */
106 caddr_t ddbstrtab; /* String table */
107 long ddbstrcnt; /* number of bytes in string table */
108 caddr_t symbase; /* malloc'ed symbold base */
109 caddr_t strbase; /* malloc'ed string base */
110 caddr_t ctftab; /* CTF table */
111 long ctfcnt; /* number of bytes in CTF table */
112 caddr_t ctfoff; /* CTF offset table */
113 caddr_t typoff; /* Type offset table */
114 long typlen; /* Number of type entries. */
115 Elf_Addr pcpu_start; /* Pre-relocation pcpu set start. */
116 Elf_Addr pcpu_stop; /* Pre-relocation pcpu set stop. */
117 Elf_Addr pcpu_base; /* Relocated pcpu set address. */
119 Elf_Addr vnet_start; /* Pre-relocation vnet set start. */
120 Elf_Addr vnet_stop; /* Pre-relocation vnet set stop. */
121 Elf_Addr vnet_base; /* Relocated vnet set address. */
124 struct link_map gdb; /* hooks for gdb */
132 TAILQ_ENTRY(elf_set) es_link;
135 TAILQ_HEAD(elf_set_head, elf_set);
137 #include <kern/kern_ctf.c>
139 static int link_elf_link_common_finish(linker_file_t);
140 static int link_elf_link_preload(linker_class_t cls,
141 const char *, linker_file_t *);
142 static int link_elf_link_preload_finish(linker_file_t);
143 static int link_elf_load_file(linker_class_t, const char *,
145 static int link_elf_lookup_symbol(linker_file_t, const char *,
147 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t,
149 static int link_elf_search_symbol(linker_file_t, caddr_t,
150 c_linker_sym_t *, long *);
152 static void link_elf_unload_file(linker_file_t);
153 static void link_elf_unload_preload(linker_file_t);
154 static int link_elf_lookup_set(linker_file_t, const char *,
155 void ***, void ***, int *);
156 static int link_elf_each_function_name(linker_file_t,
157 int (*)(const char *, void *), void *);
158 static int link_elf_each_function_nameval(linker_file_t,
159 linker_function_nameval_callback_t, void *);
160 static void link_elf_reloc_local(linker_file_t);
161 static long link_elf_symtab_get(linker_file_t, const Elf_Sym **);
162 static long link_elf_strtab_get(linker_file_t, caddr_t *);
163 static int elf_lookup(linker_file_t, Elf_Size, int, Elf_Addr *);
165 static kobj_method_t link_elf_methods[] = {
166 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
167 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
168 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
169 KOBJMETHOD(linker_unload, link_elf_unload_file),
170 KOBJMETHOD(linker_load_file, link_elf_load_file),
171 KOBJMETHOD(linker_link_preload, link_elf_link_preload),
172 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish),
173 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set),
174 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
175 KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
176 KOBJMETHOD(linker_ctf_get, link_elf_ctf_get),
177 KOBJMETHOD(linker_symtab_get, link_elf_symtab_get),
178 KOBJMETHOD(linker_strtab_get, link_elf_strtab_get),
182 static struct linker_class link_elf_class = {
183 #if ELF_TARG_CLASS == ELFCLASS32
188 link_elf_methods, sizeof(struct elf_file)
191 typedef int (*elf_reloc_fn)(linker_file_t lf, Elf_Addr relocbase,
192 const void *data, int type, elf_lookup_fn lookup);
194 static int parse_dynamic(elf_file_t);
195 static int relocate_file(elf_file_t);
196 static int relocate_file1(elf_file_t ef, elf_lookup_fn lookup,
197 elf_reloc_fn reloc, bool ifuncs);
198 static int link_elf_preload_parse_symbols(elf_file_t);
200 static struct elf_set_head set_pcpu_list;
202 static struct elf_set_head set_vnet_list;
206 elf_set_add(struct elf_set_head *list, Elf_Addr start, Elf_Addr stop, Elf_Addr base)
208 struct elf_set *set, *iter;
210 set = malloc(sizeof(*set), M_LINKER, M_WAITOK);
211 set->es_start = start;
215 TAILQ_FOREACH(iter, list, es_link) {
217 KASSERT((set->es_start < iter->es_start && set->es_stop < iter->es_stop) ||
218 (set->es_start > iter->es_start && set->es_stop > iter->es_stop),
219 ("linker sets intersection: to insert: 0x%jx-0x%jx; inserted: 0x%jx-0x%jx",
220 (uintmax_t)set->es_start, (uintmax_t)set->es_stop,
221 (uintmax_t)iter->es_start, (uintmax_t)iter->es_stop));
223 if (iter->es_start > set->es_start) {
224 TAILQ_INSERT_BEFORE(iter, set, es_link);
230 TAILQ_INSERT_TAIL(list, set, es_link);
234 elf_set_find(struct elf_set_head *list, Elf_Addr addr, Elf_Addr *start, Elf_Addr *base)
238 TAILQ_FOREACH(set, list, es_link) {
239 if (addr < set->es_start)
241 if (addr < set->es_stop) {
242 *start = set->es_start;
243 *base = set->es_base;
252 elf_set_delete(struct elf_set_head *list, Elf_Addr start)
256 TAILQ_FOREACH(set, list, es_link) {
257 if (start < set->es_start)
259 if (start == set->es_start) {
260 TAILQ_REMOVE(list, set, es_link);
265 KASSERT(0, ("deleting unknown linker set (start = 0x%jx)",
270 static void r_debug_state(struct r_debug *, struct link_map *);
273 * A list of loaded modules for GDB to use for loading symbols.
275 struct r_debug r_debug;
277 #define GDB_STATE(s) do { \
278 r_debug.r_state = s; r_debug_state(NULL, NULL); \
282 * Function for the debugger to set a breakpoint on to gain control.
285 r_debug_state(struct r_debug *dummy_one __unused,
286 struct link_map *dummy_two __unused)
291 link_elf_add_gdb(struct link_map *l)
293 struct link_map *prev;
297 if (r_debug.r_map == NULL) {
302 /* Append to list. */
303 for (prev = r_debug.r_map;
304 prev->l_next != NULL;
313 link_elf_delete_gdb(struct link_map *l)
315 if (l->l_prev == NULL) {
317 if ((r_debug.r_map = l->l_next) != NULL)
318 l->l_next->l_prev = NULL;
320 /* Remove any but first. */
321 if ((l->l_prev->l_next = l->l_next) != NULL)
322 l->l_next->l_prev = l->l_prev;
328 * The kernel symbol table starts here.
330 extern struct _dynamic _DYNAMIC;
333 link_elf_error(const char *filename, const char *s)
335 if (filename == NULL)
336 printf("kldload: %s\n", s);
338 printf("kldload: %s: %s\n", filename, s);
342 link_elf_invoke_ctors(caddr_t addr, size_t size)
347 if (addr == NULL || size == 0)
349 cnt = size / sizeof(*ctor);
351 for (i = 0; i < cnt; i++) {
358 * Actions performed after linking/loading both the preloaded kernel and any
359 * modules; whether preloaded or dynamicly loaded.
362 link_elf_link_common_finish(linker_file_t lf)
365 elf_file_t ef = (elf_file_t)lf;
370 /* Notify MD code that a module is being loaded. */
371 error = elf_cpu_load_file(lf);
377 ef->gdb.l_addr = lf->address;
378 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK);
379 strcpy(newfilename, lf->filename);
380 ef->gdb.l_name = newfilename;
381 ef->gdb.l_ld = ef->dynamic;
382 link_elf_add_gdb(&ef->gdb);
383 GDB_STATE(RT_CONSISTENT);
387 link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size);
391 extern vm_offset_t __startkernel, __endkernel;
394 link_elf_init(void* arg)
397 Elf_Addr *ctors_addrp;
398 Elf_Size *ctors_sizep;
399 caddr_t modptr, baseptr, sizeptr;
403 linker_add_class(&link_elf_class);
405 dp = (Elf_Dyn *)&_DYNAMIC;
407 modptr = preload_search_by_type("elf" __XSTRING(__ELF_WORD_SIZE) " kernel");
409 modptr = preload_search_by_type("elf kernel");
410 modname = (char *)preload_search_info(modptr, MODINFO_NAME);
413 linker_kernel_file = linker_make_file(modname, &link_elf_class);
414 if (linker_kernel_file == NULL)
415 panic("%s: Can't create linker structures for kernel",
418 ef = (elf_file_t) linker_kernel_file;
421 ef->address = (caddr_t) (__startkernel - KERNBASE);
425 #ifdef SPARSE_MAPPING
433 linker_kernel_file->address = (caddr_t)__startkernel;
434 linker_kernel_file->size = (intptr_t)(__endkernel - __startkernel);
436 linker_kernel_file->address += KERNBASE;
437 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address;
440 if (modptr != NULL) {
442 baseptr = preload_search_info(modptr, MODINFO_ADDR);
444 linker_kernel_file->address = *(caddr_t *)baseptr;
445 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
447 linker_kernel_file->size = *(size_t *)sizeptr;
448 ctors_addrp = (Elf_Addr *)preload_search_info(modptr,
449 MODINFO_METADATA | MODINFOMD_CTORS_ADDR);
450 ctors_sizep = (Elf_Size *)preload_search_info(modptr,
451 MODINFO_METADATA | MODINFOMD_CTORS_SIZE);
452 if (ctors_addrp != NULL && ctors_sizep != NULL) {
453 linker_kernel_file->ctors_addr = ef->address +
455 linker_kernel_file->ctors_size = *ctors_sizep;
458 (void)link_elf_preload_parse_symbols(ef);
461 r_debug.r_map = NULL;
462 r_debug.r_brk = r_debug_state;
463 r_debug.r_state = RT_CONSISTENT;
466 (void)link_elf_link_common_finish(linker_kernel_file);
467 linker_kernel_file->flags |= LINKER_FILE_LINKED;
468 TAILQ_INIT(&set_pcpu_list);
470 TAILQ_INIT(&set_vnet_list);
474 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_THIRD, link_elf_init, NULL);
477 link_elf_preload_parse_symbols(elf_file_t ef)
480 caddr_t ssym, esym, base;
486 if (ef->modptr == NULL)
488 pointer = preload_search_info(ef->modptr,
489 MODINFO_METADATA | MODINFOMD_SSYM);
492 ssym = *(caddr_t *)pointer;
493 pointer = preload_search_info(ef->modptr,
494 MODINFO_METADATA | MODINFOMD_ESYM);
497 esym = *(caddr_t *)pointer;
501 symcnt = *(long *)base;
502 base += sizeof(long);
503 symtab = (Elf_Sym *)base;
504 base += roundup(symcnt, sizeof(long));
506 if (base > esym || base < ssym) {
507 printf("Symbols are corrupt!\n");
511 strcnt = *(long *)base;
512 base += sizeof(long);
514 base += roundup(strcnt, sizeof(long));
516 if (base > esym || base < ssym) {
517 printf("Symbols are corrupt!\n");
521 ef->ddbsymtab = symtab;
522 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
523 ef->ddbstrtab = strtab;
524 ef->ddbstrcnt = strcnt;
530 parse_dynamic(elf_file_t ef)
533 int plttype = DT_REL;
535 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) {
539 /* From src/libexec/rtld-elf/rtld.c */
540 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
541 (ef->address + dp->d_un.d_ptr);
542 ef->nbuckets = hashtab[0];
543 ef->nchains = hashtab[1];
544 ef->buckets = hashtab + 2;
545 ef->chains = ef->buckets + ef->nbuckets;
549 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr);
552 ef->strsz = dp->d_un.d_val;
555 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr);
558 if (dp->d_un.d_val != sizeof(Elf_Sym))
562 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr);
565 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
568 ef->relsize = dp->d_un.d_val;
571 if (dp->d_un.d_val != sizeof(Elf_Rel))
575 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr);
578 ef->pltrelsize = dp->d_un.d_val;
581 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr);
584 ef->relasize = dp->d_un.d_val;
587 if (dp->d_un.d_val != sizeof(Elf_Rela))
591 plttype = dp->d_un.d_val;
592 if (plttype != DT_REL && plttype != DT_RELA)
597 dp->d_un.d_ptr = (Elf_Addr)&r_debug;
603 if (plttype == DT_RELA) {
604 ef->pltrela = (const Elf_Rela *)ef->pltrel;
606 ef->pltrelasize = ef->pltrelsize;
610 ef->ddbsymtab = ef->symtab;
611 ef->ddbsymcnt = ef->nchains;
612 ef->ddbstrtab = ef->strtab;
613 ef->ddbstrcnt = ef->strsz;
618 #define LS_PADDING 0x90909090
620 parse_dpcpu(elf_file_t ef)
623 #if defined(__i386__)
629 error = link_elf_lookup_set(&ef->lf, "pcpu", (void ***)&ef->pcpu_start,
630 (void ***)&ef->pcpu_stop, NULL);
631 /* Error just means there is no pcpu set to relocate. */
634 size = (uintptr_t)ef->pcpu_stop - (uintptr_t)ef->pcpu_start;
638 #if defined(__i386__)
639 /* In case we do find __start/stop_set_ symbols double-check. */
641 uprintf("Kernel module '%s' must be recompiled with "
642 "linker script\n", ef->lf.pathname);
646 /* Padding from linker-script correct? */
647 pad = *(uint32_t *)((uintptr_t)ef->pcpu_stop - sizeof(pad));
648 if (pad != LS_PADDING) {
649 uprintf("Kernel module '%s' must be recompiled with "
650 "linker script, invalid padding %#04x (%#04x)\n",
651 ef->lf.pathname, pad, LS_PADDING);
654 /* If we only have valid padding, nothing to do. */
659 * Allocate space in the primary pcpu area. Copy in our
660 * initialization from the data section and then initialize
661 * all per-cpu storage from that.
663 ef->pcpu_base = (Elf_Addr)(uintptr_t)dpcpu_alloc(size);
664 if (ef->pcpu_base == 0) {
665 printf("%s: pcpu module space is out of space; "
666 "cannot allocate %d for %s\n",
667 __func__, size, ef->lf.pathname);
670 memcpy((void *)ef->pcpu_base, (void *)ef->pcpu_start, size);
671 dpcpu_copy((void *)ef->pcpu_base, size);
672 elf_set_add(&set_pcpu_list, ef->pcpu_start, ef->pcpu_stop,
680 parse_vnet(elf_file_t ef)
683 #if defined(__i386__)
689 error = link_elf_lookup_set(&ef->lf, "vnet", (void ***)&ef->vnet_start,
690 (void ***)&ef->vnet_stop, NULL);
691 /* Error just means there is no vnet data set to relocate. */
694 size = (uintptr_t)ef->vnet_stop - (uintptr_t)ef->vnet_start;
698 #if defined(__i386__)
699 /* In case we do find __start/stop_set_ symbols double-check. */
701 uprintf("Kernel module '%s' must be recompiled with "
702 "linker script\n", ef->lf.pathname);
706 /* Padding from linker-script correct? */
707 pad = *(uint32_t *)((uintptr_t)ef->vnet_stop - sizeof(pad));
708 if (pad != LS_PADDING) {
709 uprintf("Kernel module '%s' must be recompiled with "
710 "linker script, invalid padding %#04x (%#04x)\n",
711 ef->lf.pathname, pad, LS_PADDING);
714 /* If we only have valid padding, nothing to do. */
719 * Allocate space in the primary vnet area. Copy in our
720 * initialization from the data section and then initialize
721 * all per-vnet storage from that.
723 ef->vnet_base = (Elf_Addr)(uintptr_t)vnet_data_alloc(size);
724 if (ef->vnet_base == 0) {
725 printf("%s: vnet module space is out of space; "
726 "cannot allocate %d for %s\n",
727 __func__, size, ef->lf.pathname);
730 memcpy((void *)ef->vnet_base, (void *)ef->vnet_start, size);
731 vnet_data_copy((void *)ef->vnet_base, size);
732 elf_set_add(&set_vnet_list, ef->vnet_start, ef->vnet_stop,
741 link_elf_link_preload(linker_class_t cls,
742 const char* filename, linker_file_t *result)
744 Elf_Addr *ctors_addrp;
745 Elf_Size *ctors_sizep;
746 caddr_t modptr, baseptr, sizeptr, dynptr;
753 /* Look to see if we have the file preloaded */
754 modptr = preload_search_by_name(filename);
758 type = (char *)preload_search_info(modptr, MODINFO_TYPE);
759 baseptr = preload_search_info(modptr, MODINFO_ADDR);
760 sizeptr = preload_search_info(modptr, MODINFO_SIZE);
761 dynptr = preload_search_info(modptr,
762 MODINFO_METADATA | MODINFOMD_DYNAMIC);
764 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 &&
765 strcmp(type, "elf module") != 0))
767 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL)
770 lf = linker_make_file(filename, &link_elf_class);
774 ef = (elf_file_t) lf;
777 ef->address = *(caddr_t *)baseptr;
778 #ifdef SPARSE_MAPPING
781 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
782 ef->dynamic = (Elf_Dyn *)dp;
783 lf->address = ef->address;
784 lf->size = *(size_t *)sizeptr;
786 ctors_addrp = (Elf_Addr *)preload_search_info(modptr,
787 MODINFO_METADATA | MODINFOMD_CTORS_ADDR);
788 ctors_sizep = (Elf_Size *)preload_search_info(modptr,
789 MODINFO_METADATA | MODINFOMD_CTORS_SIZE);
790 if (ctors_addrp != NULL && ctors_sizep != NULL) {
791 lf->ctors_addr = ef->address + *ctors_addrp;
792 lf->ctors_size = *ctors_sizep;
795 error = parse_dynamic(ef);
797 error = parse_dpcpu(ef);
800 error = parse_vnet(ef);
803 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
806 link_elf_reloc_local(lf);
812 link_elf_link_preload_finish(linker_file_t lf)
817 ef = (elf_file_t) lf;
818 error = relocate_file(ef);
821 (void)link_elf_preload_parse_symbols(ef);
823 return (link_elf_link_common_finish(lf));
827 link_elf_load_file(linker_class_t cls, const char* filename,
828 linker_file_t* result)
831 struct thread* td = curthread; /* XXX */
837 Elf_Phdr *segs[MAXSEGS];
843 Elf_Addr base_vlimit;
861 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
863 error = vn_open(&nd, &flags, 0, NULL);
866 NDFREE(&nd, NDF_ONLY_PNBUF);
867 if (nd.ni_vp->v_type != VREG) {
873 error = mac_kld_check_load(curthread->td_ucred, nd.ni_vp);
881 * Read the elf header from the file.
883 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK);
884 hdr = (Elf_Ehdr *)firstpage;
885 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0,
886 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
888 nbytes = PAGE_SIZE - resid;
897 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
898 hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
899 link_elf_error(filename, "Unsupported file layout");
903 if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
904 hdr->e_version != EV_CURRENT) {
905 link_elf_error(filename, "Unsupported file version");
909 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
913 if (hdr->e_machine != ELF_TARG_MACH) {
914 link_elf_error(filename, "Unsupported machine");
920 * We rely on the program header being in the first page.
921 * This is not strictly required by the ABI specification, but
922 * it seems to always true in practice. And, it simplifies
923 * things considerably.
925 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) &&
926 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) &&
927 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes)))
928 link_elf_error(filename, "Unreadable program headers");
931 * Scan the program header entries, and save key information.
933 * We rely on there being exactly two load segments, text and data,
936 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff);
937 phlimit = phdr + hdr->e_phnum;
940 while (phdr < phlimit) {
941 switch (phdr->p_type) {
943 if (nsegs == MAXSEGS) {
944 link_elf_error(filename, "Too many sections");
949 * XXX: We just trust they come in right order ??
967 link_elf_error(filename, "Object is not dynamically-linked");
972 link_elf_error(filename, "No sections");
978 * Allocate the entire address space of the object, to stake
979 * out our contiguous region, and to establish the base
980 * address for relocation.
982 base_vaddr = trunc_page(segs[0]->p_vaddr);
983 base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
984 segs[nsegs - 1]->p_memsz);
985 mapsize = base_vlimit - base_vaddr;
987 lf = linker_make_file(filename, &link_elf_class);
993 ef = (elf_file_t) lf;
994 #ifdef SPARSE_MAPPING
995 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT);
996 if (ef->object == NULL) {
1000 ef->address = (caddr_t) vm_map_min(kernel_map);
1001 error = vm_map_find(kernel_map, ef->object, 0,
1002 (vm_offset_t *) &ef->address, mapsize, 0, VMFS_OPTIMAL_SPACE,
1003 VM_PROT_ALL, VM_PROT_ALL, 0);
1005 vm_object_deallocate(ef->object);
1010 ef->address = malloc(mapsize, M_LINKER, M_EXEC | M_WAITOK);
1012 mapbase = ef->address;
1015 * Read the text and data sections and zero the bss.
1017 for (i = 0; i < nsegs; i++) {
1018 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
1019 error = vn_rdwr(UIO_READ, nd.ni_vp,
1020 segbase, segs[i]->p_filesz, segs[i]->p_offset,
1021 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1025 bzero(segbase + segs[i]->p_filesz,
1026 segs[i]->p_memsz - segs[i]->p_filesz);
1028 #ifdef SPARSE_MAPPING
1030 * Wire down the pages
1032 error = vm_map_wire(kernel_map,
1033 (vm_offset_t) segbase,
1034 (vm_offset_t) segbase + segs[i]->p_memsz,
1035 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
1036 if (error != KERN_SUCCESS) {
1044 /* Update profiling information with the new text segment. */
1046 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr +
1051 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr);
1053 lf->address = ef->address;
1056 error = parse_dynamic(ef);
1059 error = parse_dpcpu(ef);
1063 error = parse_vnet(ef);
1067 link_elf_reloc_local(lf);
1069 VOP_UNLOCK(nd.ni_vp, 0);
1070 error = linker_load_dependencies(lf);
1071 vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
1074 error = relocate_file(ef);
1079 * Try and load the symbol table if it's present. (you can
1082 nbytes = hdr->e_shnum * hdr->e_shentsize;
1083 if (nbytes == 0 || hdr->e_shoff == 0)
1085 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
1086 error = vn_rdwr(UIO_READ, nd.ni_vp,
1087 (caddr_t)shdr, nbytes, hdr->e_shoff,
1088 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1093 /* Read section string table */
1094 shstrindex = hdr->e_shstrndx;
1095 if (shstrindex != 0 && shdr[shstrindex].sh_type == SHT_STRTAB &&
1096 shdr[shstrindex].sh_size != 0) {
1097 nbytes = shdr[shstrindex].sh_size;
1098 shstrs = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO);
1099 error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shstrs, nbytes,
1100 shdr[shstrindex].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
1101 td->td_ucred, NOCRED, &resid, td);
1108 for (i = 0; i < hdr->e_shnum; i++) {
1109 if (shdr[i].sh_type == SHT_SYMTAB) {
1111 symstrindex = shdr[i].sh_link;
1112 } else if (shstrs != NULL && shdr[i].sh_name != 0 &&
1113 strcmp(shstrs + shdr[i].sh_name, ".ctors") == 0) {
1114 /* Record relocated address and size of .ctors. */
1115 lf->ctors_addr = mapbase + shdr[i].sh_addr - base_vaddr;
1116 lf->ctors_size = shdr[i].sh_size;
1119 if (symtabindex < 0 || symstrindex < 0)
1122 symcnt = shdr[symtabindex].sh_size;
1123 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK);
1124 strcnt = shdr[symstrindex].sh_size;
1125 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK);
1127 error = vn_rdwr(UIO_READ, nd.ni_vp,
1128 ef->symbase, symcnt, shdr[symtabindex].sh_offset,
1129 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1133 error = vn_rdwr(UIO_READ, nd.ni_vp,
1134 ef->strbase, strcnt, shdr[symstrindex].sh_offset,
1135 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
1140 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym);
1141 ef->ddbsymtab = (const Elf_Sym *)ef->symbase;
1142 ef->ddbstrcnt = strcnt;
1143 ef->ddbstrtab = ef->strbase;
1146 error = link_elf_link_common_finish(lf);
1153 VOP_UNLOCK(nd.ni_vp, 0);
1154 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
1155 if (error != 0 && lf != NULL)
1156 linker_file_unload(lf, LINKER_UNLOAD_FORCE);
1157 free(shdr, M_LINKER);
1158 free(firstpage, M_LINKER);
1159 free(shstrs, M_LINKER);
1165 elf_relocaddr(linker_file_t lf, Elf_Addr x)
1169 ef = (elf_file_t)lf;
1170 if (x >= ef->pcpu_start && x < ef->pcpu_stop)
1171 return ((x - ef->pcpu_start) + ef->pcpu_base);
1173 if (x >= ef->vnet_start && x < ef->vnet_stop)
1174 return ((x - ef->vnet_start) + ef->vnet_base);
1181 link_elf_unload_file(linker_file_t file)
1183 elf_file_t ef = (elf_file_t) file;
1185 if (ef->pcpu_base != 0) {
1186 dpcpu_free((void *)ef->pcpu_base,
1187 ef->pcpu_stop - ef->pcpu_start);
1188 elf_set_delete(&set_pcpu_list, ef->pcpu_start);
1191 if (ef->vnet_base != 0) {
1192 vnet_data_free((void *)ef->vnet_base,
1193 ef->vnet_stop - ef->vnet_start);
1194 elf_set_delete(&set_vnet_list, ef->vnet_start);
1198 if (ef->gdb.l_ld != NULL) {
1199 GDB_STATE(RT_DELETE);
1200 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
1201 link_elf_delete_gdb(&ef->gdb);
1202 GDB_STATE(RT_CONSISTENT);
1206 /* Notify MD code that a module is being unloaded. */
1207 elf_cpu_unload_file(file);
1209 if (ef->preloaded) {
1210 link_elf_unload_preload(file);
1214 #ifdef SPARSE_MAPPING
1215 if (ef->object != NULL) {
1216 vm_map_remove(kernel_map, (vm_offset_t) ef->address,
1217 (vm_offset_t) ef->address
1218 + (ef->object->size << PAGE_SHIFT));
1221 free(ef->address, M_LINKER);
1223 free(ef->symbase, M_LINKER);
1224 free(ef->strbase, M_LINKER);
1225 free(ef->ctftab, M_LINKER);
1226 free(ef->ctfoff, M_LINKER);
1227 free(ef->typoff, M_LINKER);
1231 link_elf_unload_preload(linker_file_t file)
1233 if (file->pathname != NULL)
1234 preload_delete_name(file->pathname);
1238 symbol_name(elf_file_t ef, Elf_Size r_info)
1242 if (ELF_R_SYM(r_info)) {
1243 ref = ef->symtab + ELF_R_SYM(r_info);
1244 return (ef->strtab + ref->st_name);
1250 symbol_type(elf_file_t ef, Elf_Size r_info)
1254 if (ELF_R_SYM(r_info)) {
1255 ref = ef->symtab + ELF_R_SYM(r_info);
1256 return (ELF_ST_TYPE(ref->st_info));
1258 return (STT_NOTYPE);
1262 relocate_file1(elf_file_t ef, elf_lookup_fn lookup, elf_reloc_fn reloc,
1266 const Elf_Rela *rela;
1267 const char *symname;
1269 #define APPLY_RELOCS(iter, tbl, tblsize, type) do { \
1270 for ((iter) = (tbl); (iter) != NULL && \
1271 (iter) < (tbl) + (tblsize) / sizeof(*(iter)); (iter)++) { \
1272 if ((symbol_type(ef, (iter)->r_info) == \
1274 elf_is_ifunc_reloc((iter)->r_info)) != ifuncs) \
1276 if (reloc(&ef->lf, (Elf_Addr)ef->address, \
1277 (iter), (type), lookup)) { \
1278 symname = symbol_name(ef, (iter)->r_info); \
1279 printf("link_elf: symbol %s undefined\n", \
1286 APPLY_RELOCS(rel, ef->rel, ef->relsize, ELF_RELOC_REL);
1287 APPLY_RELOCS(rela, ef->rela, ef->relasize, ELF_RELOC_RELA);
1288 APPLY_RELOCS(rel, ef->pltrel, ef->pltrelsize, ELF_RELOC_REL);
1289 APPLY_RELOCS(rela, ef->pltrela, ef->pltrelasize, ELF_RELOC_RELA);
1297 relocate_file(elf_file_t ef)
1301 error = relocate_file1(ef, elf_lookup, elf_reloc, false);
1303 error = relocate_file1(ef, elf_lookup, elf_reloc, true);
1308 * Hash function for symbol table lookup. Don't even think about changing
1309 * this. It is specified by the System V ABI.
1311 static unsigned long
1312 elf_hash(const char *name)
1314 const unsigned char *p = (const unsigned char *) name;
1315 unsigned long h = 0;
1318 while (*p != '\0') {
1319 h = (h << 4) + *p++;
1320 if ((g = h & 0xf0000000) != 0)
1328 link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
1330 elf_file_t ef = (elf_file_t) lf;
1331 unsigned long symnum;
1332 const Elf_Sym* symp;
1337 /* If we don't have a hash, bail. */
1338 if (ef->buckets == NULL || ef->nbuckets == 0) {
1339 printf("link_elf_lookup_symbol: missing symbol hash table\n");
1343 /* First, search hashed global symbols */
1344 hash = elf_hash(name);
1345 symnum = ef->buckets[hash % ef->nbuckets];
1347 while (symnum != STN_UNDEF) {
1348 if (symnum >= ef->nchains) {
1349 printf("%s: corrupt symbol table\n", __func__);
1353 symp = ef->symtab + symnum;
1354 if (symp->st_name == 0) {
1355 printf("%s: corrupt symbol table\n", __func__);
1359 strp = ef->strtab + symp->st_name;
1361 if (strcmp(name, strp) == 0) {
1362 if (symp->st_shndx != SHN_UNDEF ||
1363 (symp->st_value != 0 &&
1364 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1365 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC))) {
1366 *sym = (c_linker_sym_t) symp;
1372 symnum = ef->chains[symnum];
1375 /* If we have not found it, look at the full table (if loaded) */
1376 if (ef->symtab == ef->ddbsymtab)
1379 /* Exhaustive search */
1380 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1381 strp = ef->ddbstrtab + symp->st_name;
1382 if (strcmp(name, strp) == 0) {
1383 if (symp->st_shndx != SHN_UNDEF ||
1384 (symp->st_value != 0 &&
1385 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1386 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC))) {
1387 *sym = (c_linker_sym_t) symp;
1398 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
1399 linker_symval_t *symval)
1405 ef = (elf_file_t)lf;
1406 es = (const Elf_Sym *)sym;
1407 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
1408 symval->name = ef->strtab + es->st_name;
1409 val = (caddr_t)ef->address + es->st_value;
1410 if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
1411 val = ((caddr_t (*)(void))val)();
1412 symval->value = val;
1413 symval->size = es->st_size;
1416 if (ef->symtab == ef->ddbsymtab)
1418 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
1419 symval->name = ef->ddbstrtab + es->st_name;
1420 val = (caddr_t)ef->address + es->st_value;
1421 if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
1422 val = ((caddr_t (*)(void))val)();
1423 symval->value = val;
1424 symval->size = es->st_size;
1431 link_elf_search_symbol(linker_file_t lf, caddr_t value,
1432 c_linker_sym_t *sym, long *diffp)
1434 elf_file_t ef = (elf_file_t) lf;
1435 u_long off = (uintptr_t) (void *) value;
1439 const Elf_Sym* best = NULL;
1442 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
1443 if (es->st_name == 0)
1445 st_value = es->st_value + (uintptr_t) (void *) ef->address;
1446 if (off >= st_value) {
1447 if (off - st_value < diff) {
1448 diff = off - st_value;
1452 } else if (off - st_value == diff) {
1461 *sym = (c_linker_sym_t) best;
1467 * Look up a linker set on an ELF system.
1470 link_elf_lookup_set(linker_file_t lf, const char *name,
1471 void ***startp, void ***stopp, int *countp)
1474 linker_symval_t symval;
1476 void **start, **stop;
1477 int len, error = 0, count;
1479 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */
1480 setsym = malloc(len, M_LINKER, M_WAITOK);
1482 /* get address of first entry */
1483 snprintf(setsym, len, "%s%s", "__start_set_", name);
1484 error = link_elf_lookup_symbol(lf, setsym, &sym);
1487 link_elf_symbol_values(lf, sym, &symval);
1488 if (symval.value == 0) {
1492 start = (void **)symval.value;
1494 /* get address of last entry */
1495 snprintf(setsym, len, "%s%s", "__stop_set_", name);
1496 error = link_elf_lookup_symbol(lf, setsym, &sym);
1499 link_elf_symbol_values(lf, sym, &symval);
1500 if (symval.value == 0) {
1504 stop = (void **)symval.value;
1506 /* and the number of entries */
1507 count = stop - start;
1518 free(setsym, M_LINKER);
1523 link_elf_each_function_name(linker_file_t file,
1524 int (*callback)(const char *, void *), void *opaque)
1526 elf_file_t ef = (elf_file_t)file;
1527 const Elf_Sym *symp;
1530 /* Exhaustive search */
1531 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1532 if (symp->st_value != 0 &&
1533 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1534 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
1535 error = callback(ef->ddbstrtab + symp->st_name, opaque);
1544 link_elf_each_function_nameval(linker_file_t file,
1545 linker_function_nameval_callback_t callback, void *opaque)
1547 linker_symval_t symval;
1548 elf_file_t ef = (elf_file_t)file;
1549 const Elf_Sym* symp;
1552 /* Exhaustive search */
1553 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
1554 if (symp->st_value != 0 &&
1555 (ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
1556 ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
1557 error = link_elf_symbol_values(file,
1558 (c_linker_sym_t) symp, &symval);
1561 error = callback(file, i, &symval, opaque);
1570 elf_get_sym(linker_file_t lf, Elf_Size symidx)
1572 elf_file_t ef = (elf_file_t)lf;
1574 if (symidx >= ef->nchains)
1576 return (ef->symtab + symidx);
1580 elf_get_symname(linker_file_t lf, Elf_Size symidx)
1582 elf_file_t ef = (elf_file_t)lf;
1585 if (symidx >= ef->nchains)
1587 sym = ef->symtab + symidx;
1588 return (ef->strtab + sym->st_name);
1592 * Symbol lookup function that can be used when the symbol index is known (ie
1593 * in relocations). It uses the symbol index instead of doing a fully fledged
1594 * hash table based lookup when such is valid. For example for local symbols.
1595 * This is not only more efficient, it's also more correct. It's not always
1596 * the case that the symbol can be found through the hash table.
1599 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *res)
1601 elf_file_t ef = (elf_file_t)lf;
1604 Elf_Addr addr, start, base;
1606 /* Don't even try to lookup the symbol if the index is bogus. */
1607 if (symidx >= ef->nchains) {
1612 sym = ef->symtab + symidx;
1615 * Don't do a full lookup when the symbol is local. It may even
1616 * fail because it may not be found through the hash table.
1618 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
1619 /* Force lookup failure when we have an insanity. */
1620 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) {
1624 *res = ((Elf_Addr)ef->address + sym->st_value);
1629 * XXX we can avoid doing a hash table based lookup for global
1630 * symbols as well. This however is not always valid, so we'll
1631 * just do it the hard way for now. Performance tweaks can
1635 symbol = ef->strtab + sym->st_name;
1637 /* Force a lookup failure if the symbol name is bogus. */
1643 addr = ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps));
1644 if (addr == 0 && ELF_ST_BIND(sym->st_info) != STB_WEAK) {
1649 if (elf_set_find(&set_pcpu_list, addr, &start, &base))
1650 addr = addr - start + base;
1652 else if (elf_set_find(&set_vnet_list, addr, &start, &base))
1653 addr = addr - start + base;
1660 link_elf_reloc_local(linker_file_t lf)
1662 const Elf_Rel *rellim;
1664 const Elf_Rela *relalim;
1665 const Elf_Rela *rela;
1666 elf_file_t ef = (elf_file_t)lf;
1668 /* Perform relocations without addend if there are any: */
1669 if ((rel = ef->rel) != NULL) {
1670 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize);
1671 while (rel < rellim) {
1672 elf_reloc_local(lf, (Elf_Addr)ef->address, rel,
1673 ELF_RELOC_REL, elf_lookup);
1678 /* Perform relocations with addend if there are any: */
1679 if ((rela = ef->rela) != NULL) {
1680 relalim = (const Elf_Rela *)
1681 ((const char *)ef->rela + ef->relasize);
1682 while (rela < relalim) {
1683 elf_reloc_local(lf, (Elf_Addr)ef->address, rela,
1684 ELF_RELOC_RELA, elf_lookup);
1691 link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
1693 elf_file_t ef = (elf_file_t)lf;
1695 *symtab = ef->ddbsymtab;
1697 if (*symtab == NULL)
1700 return (ef->ddbsymcnt);
1704 link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
1706 elf_file_t ef = (elf_file_t)lf;
1708 *strtab = ef->ddbstrtab;
1710 if (*strtab == NULL)
1713 return (ef->ddbstrcnt);
1716 #if defined(__i386__) || defined(__amd64__) || defined(__aarch64__)
1718 * Use this lookup routine when performing relocations early during boot.
1719 * The generic lookup routine depends on kobj, which is not initialized
1723 elf_lookup_ifunc(linker_file_t lf, Elf_Size symidx, int deps __unused,
1727 const Elf_Sym *symp;
1730 ef = (elf_file_t)lf;
1731 symp = ef->symtab + symidx;
1732 if (ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC) {
1733 val = (caddr_t)ef->address + symp->st_value;
1734 *res = ((Elf_Addr (*)(void))val)();
1741 link_elf_ireloc(caddr_t kmdp)
1743 struct elf_file eff;
1748 bzero_early(ef, sizeof(*ef));
1751 ef->dynamic = (Elf_Dyn *)&_DYNAMIC;
1754 link_elf_preload_parse_symbols(ef);
1755 relocate_file1(ef, elf_lookup_ifunc, elf_reloc, true);