1 /* vi: set sw=4 ts=4: */
2 /* i386 ELF shared library loader suppport
4 * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
5 * David Engel, Hongjiu Lu and Mitch D'Souza
6 * Copyright (C) 2001-2004 Erik Andersen
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. The name of the above contributors may not be
16 * used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 /* Program to load an ELF binary on a linux system, and run it.
35 References to symbols in sharable libraries can be resolved by either
36 an ELF sharable library or a linux style of shared library. */
38 /* Disclaimer: I have never seen any AT&T source code for SVr4, nor have
39 I ever taken any courses on internals. This program was developed using
40 information available through the book "UNIX SYSTEM V RELEASE 4,
41 Programmers guide: Ansi C and Programming Support Tools", which did
42 a more than adequate job of explaining everything required to get this
45 extern int _dl_linux_resolve(void);
48 _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
50 ELF_RELOC *this_reloc;
57 unsigned long instr_addr;
60 rel_addr = (char *)tpnt->dynamic_info[DT_JMPREL];
61 this_reloc = (ELF_RELOC *)(intptr_t)(rel_addr + reloc_entry);
62 symtab_index = ELF_R_SYM(this_reloc->r_info);
64 symtab = (ElfW(Sym) *)(intptr_t)tpnt->dynamic_info[DT_SYMTAB];
65 strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
66 symname = strtab + symtab[symtab_index].st_name;
68 /* Address of the jump instruction to fix up. */
69 instr_addr = ((unsigned long)this_reloc->r_offset +
70 (unsigned long)tpnt->loadaddr);
71 got_addr = (char **)instr_addr;
73 /* Get the address of the GOT entry. */
74 new_addr = _dl_find_hash(symname, &_dl_loaded_modules->symbol_scope, tpnt, ELF_RTYPE_CLASS_PLT, NULL);
75 if (unlikely(!new_addr)) {
76 _dl_dprintf(2, "%s: can't resolve symbol '%s' in lib '%s'.\n", _dl_progname, symname, tpnt->libname);
80 #if defined (__SUPPORT_LD_DEBUG__)
81 if ((unsigned long)got_addr < 0x40000000) {
82 if (_dl_debug_bindings) {
83 _dl_dprintf(_dl_debug_file, "\nresolve function: %s", symname);
85 _dl_dprintf(_dl_debug_file,
86 "\n\tpatched: %x ==> %x @ %x",
87 *got_addr, new_addr, got_addr);
90 if (!_dl_debug_nofixups) {
97 return (unsigned long)new_addr;
101 _dl_parse(struct elf_resolve *tpnt, struct r_scope_elem *scope,
102 unsigned long rel_addr, unsigned long rel_size,
103 int (*reloc_fnc)(struct elf_resolve *tpnt, struct r_scope_elem *scope,
104 ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab))
112 /* Parse the relocation information. */
113 rpnt = (ELF_RELOC *)(intptr_t)rel_addr;
114 rel_size /= sizeof(ELF_RELOC);
116 symtab = (ElfW(Sym) *)(intptr_t)tpnt->dynamic_info[DT_SYMTAB];
117 strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
119 for (i = 0; i < rel_size; i++, rpnt++) {
122 symtab_index = ELF_R_SYM(rpnt->r_info);
124 debug_sym(symtab, strtab, symtab_index);
125 debug_reloc(symtab, strtab, rpnt);
127 res = reloc_fnc(tpnt, scope, rpnt, symtab, strtab);
132 _dl_dprintf(2, "\n%s: ", _dl_progname);
135 _dl_dprintf(2, "symbol '%s': ",
136 strtab + symtab[symtab_index].st_name);
138 if (unlikely(res < 0)) {
139 int reloc_type = ELF_R_TYPE(rpnt->r_info);
141 #if defined (__SUPPORT_LD_DEBUG__)
142 _dl_dprintf(2, "can't handle reloc type '%s' in lib '%s'\n",
143 _dl_reltypes(reloc_type), tpnt->libname);
145 _dl_dprintf(2, "can't handle reloc type %x in lib '%s'\n",
146 reloc_type, tpnt->libname);
149 } else if (unlikely(res > 0)) {
150 _dl_dprintf(2, "can't resolve symbol in lib '%s'.\n", tpnt->libname);
159 _dl_do_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
160 ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
165 struct elf_resolve *tls_tpnt = NULL;
166 unsigned long *reloc_addr;
167 unsigned long symbol_addr;
168 #if defined (__SUPPORT_LD_DEBUG__)
169 unsigned long old_val;
171 struct symbol_ref sym_ref;
173 reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
174 reloc_type = ELF_R_TYPE(rpnt->r_info);
175 symtab_index = ELF_R_SYM(rpnt->r_info);
177 sym_ref.sym = &symtab[symtab_index];
179 symname = strtab + symtab[symtab_index].st_name;
182 symbol_addr = (unsigned long)_dl_find_hash(symname, scope, tpnt,
183 elf_machine_type_class(reloc_type), &sym_ref);
186 * We want to allow undefined references to weak symbols - this
187 * might have been intentional. We should not be linking local
188 * symbols here, so all bases should be covered.
190 if (unlikely(!symbol_addr && (ELF_ST_TYPE(symtab[symtab_index].st_info) != STT_TLS)
191 && ELF_ST_BIND(symtab[symtab_index].st_info) != STB_WEAK))
193 if (_dl_trace_prelink) {
194 _dl_debug_lookup (symname, tpnt, &symtab[symtab_index],
195 &sym_ref, elf_machine_type_class(reloc_type));
197 tls_tpnt = sym_ref.tpnt;
199 symbol_addr = symtab[symtab_index].st_value;
203 #if defined (__SUPPORT_LD_DEBUG__)
204 /* Start: aw11: fixed pagefault with empty relocations */
205 if (reloc_type != R_386_NONE) old_val = *reloc_addr; else old_val = 0;
209 switch (reloc_type) {
213 *reloc_addr += symbol_addr;
216 *reloc_addr += symbol_addr - (unsigned long)reloc_addr;
220 *reloc_addr = symbol_addr;
223 *reloc_addr += (unsigned long)tpnt->loadaddr;
227 #if defined (__SUPPORT_LD_DEBUG__)
229 _dl_dprintf(_dl_debug_file,
230 "\n%s move %d bytes from %x to %x",
231 symname, symtab[symtab_index].st_size,
232 symbol_addr, reloc_addr);
235 _dl_memcpy((char *)reloc_addr,
237 symtab[symtab_index].st_size);
240 #if defined USE_TLS && USE_TLS
241 case R_386_TLS_DTPMOD32:
242 *reloc_addr = tls_tpnt->l_tls_modid;
244 case R_386_TLS_DTPOFF32:
245 /* During relocation all TLS symbols are defined and used.
246 * Therefore the offset is already correct. */
247 *reloc_addr = symbol_addr;
249 case R_386_TLS_TPOFF32:
250 /* The offset is positive, backward from the thread pointer. */
251 CHECK_STATIC_TLS((struct link_map*) tls_tpnt);
252 *reloc_addr += tls_tpnt->l_tls_offset - symbol_addr;
254 case R_386_TLS_TPOFF:
255 /* The offset is negative, forward from the thread pointer. */
256 CHECK_STATIC_TLS((struct link_map*) tls_tpnt);
257 *reloc_addr += symbol_addr - tls_tpnt->l_tls_offset;
264 #if defined (__SUPPORT_LD_DEBUG__)
265 if (_dl_debug_reloc && _dl_debug_detail)
266 _dl_dprintf(_dl_debug_file, "\n\tpatched: %x ==> %x @ %x\n",
267 old_val, *reloc_addr, reloc_addr);
274 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
275 ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
278 unsigned long *reloc_addr;
279 #if defined (__SUPPORT_LD_DEBUG__)
280 unsigned long old_val;
287 reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
288 reloc_type = ELF_R_TYPE(rpnt->r_info);
290 #if defined (__SUPPORT_LD_DEBUG__)
291 old_val = *reloc_addr;
294 switch (reloc_type) {
298 *reloc_addr += (unsigned long)tpnt->loadaddr;
304 #if defined (__SUPPORT_LD_DEBUG__)
305 if (_dl_debug_reloc && _dl_debug_detail)
306 _dl_dprintf(_dl_debug_file, "\n\tpatched: %x ==> %x @ %x\n",
307 old_val, *reloc_addr, reloc_addr);
314 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
315 unsigned long rel_addr,
316 unsigned long rel_size)
318 (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
322 _dl_parse_relocation_information(struct dyn_elf *rpnt,
323 struct r_scope_elem *scope,
324 unsigned long rel_addr,
325 unsigned long rel_size)
327 return _dl_parse(rpnt->dyn, scope, rel_addr, rel_size, _dl_do_reloc);