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.
29 * Dynamic linker for ELF.
31 * John Polstra <jdp@polstra.com>.
34 #include <sys/param.h>
36 #include <machine/segments.h>
37 #include <machine/sysarch.h>
53 * Process the special R_386_COPY relocations in the main program. These
54 * copy data from a shared object into a region in the main program's BSS
57 * Returns 0 on success, -1 on failure.
60 do_copy_relocations(Obj_Entry *dstobj)
62 const Elf_Rel *rellim;
65 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */
67 rellim = (const Elf_Rel *) ((caddr_t) dstobj->rel + dstobj->relsize);
68 for (rel = dstobj->rel; rel < rellim; rel++) {
69 if (ELF_R_TYPE(rel->r_info) == R_386_COPY) {
71 const Elf_Sym *dstsym;
76 const Elf_Sym *srcsym;
80 dstaddr = (void *) (dstobj->relocbase + rel->r_offset);
81 dstsym = dstobj->symtab + ELF_R_SYM(rel->r_info);
82 name = dstobj->strtab + dstsym->st_name;
83 hash = elf_hash(name);
84 size = dstsym->st_size;
85 ve = fetch_ventry(dstobj, ELF_R_SYM(rel->r_info));
87 for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next)
88 if ((srcsym = symlook_obj(name, hash, srcobj, ve, 0)) != NULL)
92 _rtld_error("Undefined symbol \"%s\" referenced from COPY"
93 " relocation in %s", name, dstobj->path);
97 srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value);
98 memcpy(dstaddr, srcaddr, size);
105 /* Initialize the special GOT entries. */
107 init_pltgot(Obj_Entry *obj)
109 if (obj->pltgot != NULL) {
110 obj->pltgot[1] = (Elf_Addr) obj;
111 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
115 /* Process the non-PLT relocations. */
117 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
119 const Elf_Rel *rellim;
122 int bytes = obj->nchains * sizeof(SymCache);
126 * The dynamic loader may be called from a thread, we have
127 * limited amounts of stack available so we cannot use alloca().
129 cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
130 if (cache == MAP_FAILED)
133 rellim = (const Elf_Rel *) ((caddr_t) obj->rel + obj->relsize);
134 for (rel = obj->rel; rel < rellim; rel++) {
135 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
137 switch (ELF_R_TYPE(rel->r_info)) {
145 const Obj_Entry *defobj;
147 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
152 *where += (Elf_Addr) (defobj->relocbase + def->st_value);
158 * I don't think the dynamic linker should ever see this
159 * type of relocation. But the binutils-2.6 tools sometimes
164 const Obj_Entry *defobj;
166 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
172 (Elf_Addr) (defobj->relocbase + def->st_value) -
179 * These are deferred until all other relocations have
180 * been done. All we do here is make sure that the COPY
181 * relocation is not in a shared library. They are allowed
182 * only in executable files.
184 if (!obj->mainprog) {
185 _rtld_error("%s: Unexpected R_386_COPY relocation"
186 " in shared library", obj->path);
194 const Obj_Entry *defobj;
196 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
201 *where = (Elf_Addr) (defobj->relocbase + def->st_value);
206 *where += (Elf_Addr) obj->relocbase;
209 case R_386_TLS_TPOFF:
212 const Obj_Entry *defobj;
214 def = find_symdef(ELF_R_SYM(rel->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);
239 case R_386_TLS_DTPMOD32:
242 const Obj_Entry *defobj;
244 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
249 *where += (Elf_Addr) defobj->tlsindex;
253 case R_386_TLS_DTPOFF32:
256 const Obj_Entry *defobj;
258 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
263 *where += (Elf_Addr) def->st_value;
268 _rtld_error("%s: Unsupported relocation type %d"
269 " in non-PLT relocations\n", obj->path,
270 ELF_R_TYPE(rel->r_info));
277 munmap(cache, bytes);
281 /* Process the PLT relocations. */
283 reloc_plt(Obj_Entry *obj)
285 const Elf_Rel *rellim;
288 rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
289 for (rel = obj->pltrel; rel < rellim; rel++) {
292 assert(ELF_R_TYPE(rel->r_info) == R_386_JMP_SLOT);
294 /* Relocate the GOT slot pointing into the PLT. */
295 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
296 *where += (Elf_Addr)obj->relocbase;
301 /* Relocate the jump slots in an object. */
303 reloc_jmpslots(Obj_Entry *obj)
305 const Elf_Rel *rellim;
308 if (obj->jmpslots_done)
310 rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
311 for (rel = obj->pltrel; rel < rellim; rel++) {
312 Elf_Addr *where, target;
314 const Obj_Entry *defobj;
316 assert(ELF_R_TYPE(rel->r_info) == R_386_JMP_SLOT);
317 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
318 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
321 target = (Elf_Addr)(defobj->relocbase + def->st_value);
322 reloc_jmpslot(where, target, defobj, obj, rel);
324 obj->jmpslots_done = true;
329 allocate_initial_tls(Obj_Entry *objs)
334 * Fix the size of the static TLS block by using the maximum
335 * offset allocated so far and adding a bit for dynamic modules to
338 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
339 tls = allocate_tls(objs, NULL, 3*sizeof(Elf_Addr), sizeof(Elf_Addr));
340 i386_set_gsbase(tls);
344 __attribute__((__regparm__(1)))
345 void *___tls_get_addr(tls_index *ti)
350 __asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
353 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);
357 void *__tls_get_addr(tls_index *ti)
362 __asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
365 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);