2 * Copyright 1996, 1997, 1998, 1999 John D. Polstra.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 * $FreeBSD: src/libexec/rtld-elf/amd64/reloc.c,v 1.18 2006/03/28 06:09:24 davidxu Exp $
26 * $DragonFly: src/libexec/rtld-elf/amd64/reloc.c,v 1.1 2006/07/27 00:40:35 corecode Exp $
30 * Dynamic linker for ELF.
32 * John Polstra <jdp@polstra.com>.
35 #include <sys/param.h>
39 #include <machine/sysarch.h>
40 #include <machine/tls.h>
56 * Process the special R_X86_64_COPY relocations in the main program. These
57 * copy data from a shared object into a region in the main program's BSS
60 * Returns 0 on success, -1 on failure.
63 do_copy_relocations(Obj_Entry *dstobj)
65 const Elf_Rela *relalim;
68 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */
70 relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize);
71 for (rela = dstobj->rela; rela < relalim; rela++) {
72 if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) {
74 const Elf_Sym *dstsym;
79 const Elf_Sym *srcsym;
82 dstaddr = (void *) (dstobj->relocbase + rela->r_offset);
83 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
84 name = dstobj->strtab + dstsym->st_name;
85 hash = elf_hash(name);
86 size = dstsym->st_size;
88 for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next)
89 if ((srcsym = symlook_obj(name, hash, srcobj, false)) != NULL)
93 _rtld_error("Undefined symbol \"%s\" referenced from COPY"
94 " relocation in %s", name, dstobj->path);
98 srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value);
99 memcpy(dstaddr, srcaddr, size);
106 /* Initialize the special GOT entries. */
108 init_pltgot(Obj_Entry *obj)
110 if (obj->pltgot != NULL) {
111 obj->pltgot[1] = (Elf_Addr) obj;
112 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
116 /* Process the non-PLT relocations. */
118 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
120 const Elf_Rela *relalim;
121 const Elf_Rela *rela;
123 int bytes = obj->nchains * sizeof(SymCache);
127 * The dynamic loader may be called from a thread, we have
128 * limited amounts of stack available so we cannot use alloca().
130 cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
131 if (cache == MAP_FAILED)
134 relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
135 for (rela = obj->rela; rela < relalim; rela++) {
136 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
137 Elf32_Addr *where32 = (Elf32_Addr *)where;
139 switch (ELF_R_TYPE(rela->r_info)) {
147 const Obj_Entry *defobj;
149 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
154 *where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend);
160 * I don't think the dynamic linker should ever see this
161 * type of relocation. But the binutils-2.6 tools sometimes
166 const Obj_Entry *defobj;
168 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
173 *where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase +
174 def->st_value + rela->r_addend - (Elf_Addr) where);
177 /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */
181 * These are deferred until all other relocations have
182 * been done. All we do here is make sure that the COPY
183 * relocation is not in a shared library. They are allowed
184 * only in executable files.
186 if (!obj->mainprog) {
187 _rtld_error("%s: Unexpected R_X86_64_COPY relocation"
188 " in shared library", obj->path);
193 case R_X86_64_GLOB_DAT:
196 const Obj_Entry *defobj;
198 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
203 *where = (Elf_Addr) (defobj->relocbase + def->st_value);
207 case R_X86_64_TPOFF64:
210 const Obj_Entry *defobj;
212 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
218 * We lazily allocate offsets for static TLS as we
219 * see the first relocation that references the
220 * TLS block. This allows us to support (small
221 * amounts of) static TLS in dynamically loaded
222 * modules. If we run out of space, we generate an
225 if (!defobj->tls_done) {
226 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
227 _rtld_error("%s: No space available for static "
228 "Thread Local Storage", obj->path);
233 *where = (Elf_Addr) (def->st_value - defobj->tlsoffset +
238 case R_X86_64_TPOFF32:
241 const Obj_Entry *defobj;
243 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
249 * We lazily allocate offsets for static TLS as we
250 * see the first relocation that references the
251 * TLS block. This allows us to support (small
252 * amounts of) static TLS in dynamically loaded
253 * modules. If we run out of space, we generate an
256 if (!defobj->tls_done) {
257 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
258 _rtld_error("%s: No space available for static "
259 "Thread Local Storage", obj->path);
264 *where32 = (Elf32_Addr) (def->st_value -
270 case R_X86_64_DTPMOD64:
273 const Obj_Entry *defobj;
275 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
280 *where += (Elf_Addr) defobj->tlsindex;
284 case R_X86_64_DTPOFF64:
287 const Obj_Entry *defobj;
289 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
294 *where += (Elf_Addr) (def->st_value + rela->r_addend);
298 case R_X86_64_DTPOFF32:
301 const Obj_Entry *defobj;
303 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
308 *where32 += (Elf32_Addr) (def->st_value + rela->r_addend);
312 case R_X86_64_RELATIVE:
313 *where = (Elf_Addr)(obj->relocbase + rela->r_addend);
316 /* missing: R_X86_64_GOTPCREL, R_X86_64_32, R_X86_64_32S, R_X86_64_16, R_X86_64_PC16, R_X86_64_8, R_X86_64_PC8 */
319 _rtld_error("%s: Unsupported relocation type %u"
320 " in non-PLT relocations\n", obj->path,
321 (unsigned int)ELF_R_TYPE(rela->r_info));
328 munmap(cache, bytes);
332 /* Process the PLT relocations. */
334 reloc_plt(Obj_Entry *obj)
336 const Elf_Rela *relalim;
337 const Elf_Rela *rela;
339 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
340 for (rela = obj->pltrela; rela < relalim; rela++) {
343 assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
345 /* Relocate the GOT slot pointing into the PLT. */
346 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
347 *where += (Elf_Addr)obj->relocbase;
352 /* Relocate the jump slots in an object. */
354 reloc_jmpslots(Obj_Entry *obj)
356 const Elf_Rela *relalim;
357 const Elf_Rela *rela;
359 if (obj->jmpslots_done)
361 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
362 for (rela = obj->pltrela; rela < relalim; rela++) {
363 Elf_Addr *where, target;
365 const Obj_Entry *defobj;
367 assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
368 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
369 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL);
372 target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend);
373 reloc_jmpslot(where, target);
375 obj->jmpslots_done = true;
379 void *__tls_get_addr(tls_index *ti)
384 return tls_get_addr_common(&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);
388 __tls_get_addr_tcb(struct tls_tcb *tcb, tls_index *ti)
390 return tls_get_addr_common(&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);