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 1.20 2010/12/25 08:51:20 kib Exp $
29 * Dynamic linker for ELF.
31 * John Polstra <jdp@polstra.com>.
34 #include <sys/param.h>
38 #include <machine/sysarch.h>
39 #include <machine/tls.h>
55 * Process the special R_X86_64_COPY relocations in the main program. These
56 * copy data from a shared object into a region in the main program's BSS
59 * Returns 0 on success, -1 on failure.
62 do_copy_relocations(Obj_Entry *dstobj)
64 const Elf_Rela *relalim;
67 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */
69 relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize);
70 for (rela = dstobj->rela; rela < relalim; rela++) {
71 if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) {
73 const Elf_Sym *dstsym;
78 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;
87 ve = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info));
89 for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next)
90 if ((srcsym = symlook_obj(name, hash, srcobj, ve, 0)) != NULL)
94 _rtld_error("Undefined symbol \"%s\" referenced from COPY"
95 " relocation in %s", name, dstobj->path);
99 srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value);
100 memcpy(dstaddr, srcaddr, size);
107 /* Initialize the special GOT entries. */
109 init_pltgot(Obj_Entry *obj)
111 if (obj->pltgot != NULL) {
112 obj->pltgot[1] = (Elf_Addr) obj;
113 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
117 /* Process the non-PLT relocations. */
119 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
121 const Elf_Rela *relalim;
122 const Elf_Rela *rela;
127 * The dynamic loader may be called from a thread, we have
128 * limited amounts of stack available so we cannot use alloca().
130 if (obj != obj_rtld) {
131 cache = calloc(obj->nchains, sizeof(SymCache));
132 /* No need to check for NULL here */
136 relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
137 for (rela = obj->rela; rela < relalim; rela++) {
138 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
139 Elf32_Addr *where32 = (Elf32_Addr *)where;
141 switch (ELF_R_TYPE(rela->r_info)) {
149 const Obj_Entry *defobj;
151 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
156 *where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend);
162 * I don't think the dynamic linker should ever see this
163 * type of relocation. But the binutils-2.6 tools sometimes
168 const Obj_Entry *defobj;
170 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
175 *where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase +
176 def->st_value + rela->r_addend - (Elf_Addr) where);
179 /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */
183 * These are deferred until all other relocations have
184 * been done. All we do here is make sure that the COPY
185 * relocation is not in a shared library. They are allowed
186 * only in executable files.
188 if (!obj->mainprog) {
189 _rtld_error("%s: Unexpected R_X86_64_COPY relocation"
190 " in shared library", obj->path);
195 case R_X86_64_GLOB_DAT:
198 const Obj_Entry *defobj;
200 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
205 *where = (Elf_Addr) (defobj->relocbase + def->st_value);
209 case R_X86_64_TPOFF64:
212 const Obj_Entry *defobj;
214 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
220 * We lazily allocate offsets for static TLS as we
221 * see the first relocation that references the
222 * TLS block. This allows us to support (small
223 * amounts of) static TLS in dynamically loaded
224 * modules. If we run out of space, we generate an
227 if (!defobj->tls_done) {
228 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
229 _rtld_error("%s: No space available for static "
230 "Thread Local Storage", obj->path);
235 *where = (Elf_Addr) (def->st_value - defobj->tlsoffset +
240 case R_X86_64_TPOFF32:
243 const Obj_Entry *defobj;
245 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
251 * We lazily allocate offsets for static TLS as we
252 * see the first relocation that references the
253 * TLS block. This allows us to support (small
254 * amounts of) static TLS in dynamically loaded
255 * modules. If we run out of space, we generate an
258 if (!defobj->tls_done) {
259 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
260 _rtld_error("%s: No space available for static "
261 "Thread Local Storage", obj->path);
266 *where32 = (Elf32_Addr) (def->st_value -
272 case R_X86_64_DTPMOD64:
275 const Obj_Entry *defobj;
277 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
282 *where += (Elf_Addr) defobj->tlsindex;
286 case R_X86_64_DTPOFF64:
289 const Obj_Entry *defobj;
291 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
296 *where += (Elf_Addr) (def->st_value + rela->r_addend);
300 case R_X86_64_DTPOFF32:
303 const Obj_Entry *defobj;
305 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
310 *where32 += (Elf32_Addr) (def->st_value + rela->r_addend);
314 case R_X86_64_RELATIVE:
315 *where = (Elf_Addr)(obj->relocbase + rela->r_addend);
318 /* 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 */
321 _rtld_error("%s: Unsupported relocation type %u"
322 " in non-PLT relocations\n", obj->path,
323 (unsigned int)ELF_R_TYPE(rela->r_info));
334 /* Process the PLT relocations. */
336 reloc_plt(Obj_Entry *obj)
338 const Elf_Rela *relalim;
339 const Elf_Rela *rela;
341 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
342 for (rela = obj->pltrela; rela < relalim; rela++) {
345 switch(ELF_R_TYPE(rela->r_info)) {
346 case R_X86_64_JMP_SLOT:
347 /* Relocate the GOT slot pointing into the PLT. */
348 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
349 *where += (Elf_Addr)obj->relocbase;
353 _rtld_error("Unknown relocation type %x in PLT",
354 (unsigned int)ELF_R_TYPE(rela->r_info));
361 /* Relocate the jump slots in an object. */
363 reloc_jmpslots(Obj_Entry *obj)
365 const Elf_Rela *relalim;
366 const Elf_Rela *rela;
368 if (obj->jmpslots_done)
370 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
371 for (rela = obj->pltrela; rela < relalim; rela++) {
372 Elf_Addr *where, target;
374 const Obj_Entry *defobj;
376 switch (ELF_R_TYPE(rela->r_info)) {
377 case R_X86_64_JMP_SLOT:
378 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
379 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL);
382 target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend);
383 reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela);
387 _rtld_error("Unknown relocation type %x in PLT",
388 (unsigned int)ELF_R_TYPE(rela->r_info));
392 obj->jmpslots_done = true;
396 void *__tls_get_addr(tls_index *ti)
401 return tls_get_addr_common((Elf_Addr **)&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);
405 __tls_get_addr_tcb(struct tls_tcb *tcb, tls_index *ti)
407 return tls_get_addr_common((Elf_Addr **)&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);