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 = ELF32_R_SYM(this_reloc->r_info);
64 symtab = (Elf32_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, tpnt->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 dyn_elf *scope,
102 unsigned long rel_addr, unsigned long rel_size,
103 int (*reloc_fnc)(struct elf_resolve *tpnt, struct dyn_elf *scope,
104 ELF_RELOC *rpnt, Elf32_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 = (Elf32_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 = ELF32_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 = ELF32_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 dyn_elf *scope,
160 ELF_RELOC *rpnt, Elf32_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 = ELF32_R_TYPE(rpnt->r_info);
175 symtab_index = ELF32_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 && ELF32_ST_BIND(symtab[symtab_index].st_info) != STB_WEAK))
193 tls_tpnt = sym_ref.tpnt;
195 symbol_addr = symtab[symtab_index].st_value;
200 #if defined (__SUPPORT_LD_DEBUG__)
201 /* Start: aw11: fixed pagefualt with empty relocations */
202 if (reloc_type != R_386_NONE) old_val = *reloc_addr; else old_val = 0;
206 switch (reloc_type) {
210 *reloc_addr += symbol_addr;
213 *reloc_addr += symbol_addr - (unsigned long)reloc_addr;
217 *reloc_addr = symbol_addr;
220 *reloc_addr += (unsigned long)tpnt->loadaddr;
224 #if defined (__SUPPORT_LD_DEBUG__)
226 _dl_dprintf(_dl_debug_file,
227 "\n%s move %d bytes from %x to %x",
228 symname, symtab[symtab_index].st_size,
229 symbol_addr, reloc_addr);
232 _dl_memcpy((char *)reloc_addr,
234 symtab[symtab_index].st_size);
237 #if defined USE_TLS && USE_TLS
238 case R_386_TLS_DTPMOD32:
239 *reloc_addr = tls_tpnt->l_tls_modid;
241 case R_386_TLS_DTPOFF32:
242 /* During relocation all TLS symbols are defined and used.
243 * Therefore the offset is already correct. */
244 *reloc_addr = symbol_addr;
246 case R_386_TLS_TPOFF32:
247 /* The offset is positive, backward from the thread pointer. */
248 CHECK_STATIC_TLS((struct link_map*) tls_tpnt);
249 *reloc_addr += tls_tpnt->l_tls_offset - symbol_addr;
251 case R_386_TLS_TPOFF:
252 /* The offset is negative, forward from the thread pointer. */
253 CHECK_STATIC_TLS((struct link_map*) tls_tpnt);
254 *reloc_addr += symbol_addr - tls_tpnt->l_tls_offset;
261 #if defined (__SUPPORT_LD_DEBUG__)
262 if (_dl_debug_reloc && _dl_debug_detail)
263 _dl_dprintf(_dl_debug_file, "\n\tpatched: %x ==> %x @ %x\n",
264 old_val, *reloc_addr, reloc_addr);
271 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
272 ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
275 unsigned long *reloc_addr;
276 #if defined (__SUPPORT_LD_DEBUG__)
277 unsigned long old_val;
284 reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
285 reloc_type = ELF32_R_TYPE(rpnt->r_info);
287 #if defined (__SUPPORT_LD_DEBUG__)
288 old_val = *reloc_addr;
291 switch (reloc_type) {
295 *reloc_addr += (unsigned long)tpnt->loadaddr;
301 #if defined (__SUPPORT_LD_DEBUG__)
302 if (_dl_debug_reloc && _dl_debug_detail)
303 _dl_dprintf(_dl_debug_file, "\n\tpatched: %x ==> %x @ %x\n",
304 old_val, *reloc_addr, reloc_addr);
311 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
312 unsigned long rel_addr,
313 unsigned long rel_size)
315 (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
319 _dl_parse_relocation_information(struct dyn_elf *rpnt,
320 unsigned long rel_addr,
321 unsigned long rel_size)
323 return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size, _dl_do_reloc);