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)
51 ELF_RELOC *this_reloc;
58 unsigned long instr_addr;
61 rel_addr = (char *)tpnt->dynamic_info[DT_JMPREL];
62 this_reloc = (ELF_RELOC *)(intptr_t)(rel_addr + reloc_entry);
63 reloc_type = ELF32_R_TYPE(this_reloc->r_info);
64 symtab_index = ELF32_R_SYM(this_reloc->r_info);
66 symtab = (Elf32_Sym *)(intptr_t)tpnt->dynamic_info[DT_SYMTAB];
67 strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
68 symname = strtab + symtab[symtab_index].st_name;
70 if (unlikely(reloc_type != R_386_JMP_SLOT)) {
71 _dl_dprintf(2, "%s: Incorrect relocation type in jump relocations\n",
76 /* Address of the jump instruction to fix up. */
77 instr_addr = ((unsigned long)this_reloc->r_offset +
78 (unsigned long)tpnt->loadaddr);
79 got_addr = (char **)instr_addr;
81 /* Get the address of the GOT entry. */
82 new_addr = _dl_find_hash(symname, tpnt->symbol_scope, tpnt, ELF_RTYPE_CLASS_PLT);
83 if (unlikely(!new_addr)) {
84 _dl_dprintf(2, "%s: can't resolve symbol '%s' in lib '%s'.\n", _dl_progname, symname, tpnt->libname);
88 #if defined (__SUPPORT_LD_DEBUG__)
89 if ((unsigned long)got_addr < 0x40000000) {
90 if (_dl_debug_bindings) {
91 _dl_dprintf(_dl_debug_file, "\nresolve function: %s", symname);
93 _dl_dprintf(_dl_debug_file,
94 "\n\tpatched: %x ==> %x @ %x",
95 *got_addr, new_addr, got_addr);
98 if (!_dl_debug_nofixups) {
102 *got_addr = new_addr;
105 return (unsigned long)new_addr;
109 _dl_parse(struct elf_resolve *tpnt, struct dyn_elf *scope,
110 unsigned long rel_addr, unsigned long rel_size,
111 int (*reloc_fnc)(struct elf_resolve *tpnt, struct dyn_elf *scope,
112 ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab))
120 /* Parse the relocation information. */
121 rpnt = (ELF_RELOC *)(intptr_t)rel_addr;
122 rel_size /= sizeof(ELF_RELOC);
124 symtab = (Elf32_Sym *)(intptr_t)tpnt->dynamic_info[DT_SYMTAB];
125 strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
127 for (i = 0; i < rel_size; i++, rpnt++) {
130 symtab_index = ELF32_R_SYM(rpnt->r_info);
132 debug_sym(symtab, strtab, symtab_index);
133 debug_reloc(symtab, strtab, rpnt);
135 res = reloc_fnc(tpnt, scope, rpnt, symtab, strtab);
140 _dl_dprintf(2, "\n%s: ", _dl_progname);
143 _dl_dprintf(2, "symbol '%s': ",
144 strtab + symtab[symtab_index].st_name);
146 if (unlikely(res < 0)) {
147 int reloc_type = ELF32_R_TYPE(rpnt->r_info);
149 #if defined (__SUPPORT_LD_DEBUG__)
150 _dl_dprintf(2, "can't handle reloc type '%s' in lib '%s'\n",
151 _dl_reltypes(reloc_type), tpnt->libname);
153 _dl_dprintf(2, "can't handle reloc type %x in lib '%s'\n",
154 reloc_type, tpnt->libname);
157 } else if (unlikely(res > 0)) {
158 _dl_dprintf(2, "can't resolve symbol in lib '%s'.\n", tpnt->libname);
167 _dl_do_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
168 ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
173 unsigned long *reloc_addr;
174 unsigned long symbol_addr;
175 #if defined (__SUPPORT_LD_DEBUG__)
176 unsigned long old_val;
179 reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
180 reloc_type = ELF32_R_TYPE(rpnt->r_info);
181 symtab_index = ELF32_R_SYM(rpnt->r_info);
183 symname = strtab + symtab[symtab_index].st_name;
186 symbol_addr = (unsigned long)_dl_find_hash(symname, scope, tpnt,
187 elf_machine_type_class(reloc_type));
190 * We want to allow undefined references to weak symbols - this
191 * might have been intentional. We should not be linking local
192 * symbols here, so all bases should be covered.
194 if (unlikely(!symbol_addr && ELF32_ST_BIND(symtab[symtab_index].st_info) != STB_WEAK))
198 #if defined (__SUPPORT_LD_DEBUG__)
199 old_val = *reloc_addr;
202 switch (reloc_type) {
206 *reloc_addr += symbol_addr;
209 *reloc_addr += symbol_addr - (unsigned long)reloc_addr;
213 *reloc_addr = symbol_addr;
216 *reloc_addr += (unsigned long)tpnt->loadaddr;
220 #if defined (__SUPPORT_LD_DEBUG__)
222 _dl_dprintf(_dl_debug_file,
223 "\n%s move %d bytes from %x to %x",
224 symname, symtab[symtab_index].st_size,
225 symbol_addr, reloc_addr);
228 _dl_memcpy((char *)reloc_addr,
230 symtab[symtab_index].st_size);
237 #if defined (__SUPPORT_LD_DEBUG__)
238 if (_dl_debug_reloc && _dl_debug_detail)
239 _dl_dprintf(_dl_debug_file, "\n\tpatched: %x ==> %x @ %x",
240 old_val, *reloc_addr, reloc_addr);
247 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
248 ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
251 unsigned long *reloc_addr;
252 #if defined (__SUPPORT_LD_DEBUG__)
253 unsigned long old_val;
260 reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
261 reloc_type = ELF32_R_TYPE(rpnt->r_info);
263 #if defined (__SUPPORT_LD_DEBUG__)
264 old_val = *reloc_addr;
267 switch (reloc_type) {
271 *reloc_addr += (unsigned long)tpnt->loadaddr;
277 #if defined (__SUPPORT_LD_DEBUG__)
278 if (_dl_debug_reloc && _dl_debug_detail)
279 _dl_dprintf(_dl_debug_file, "\n\tpatched: %x ==> %x @ %x",
280 old_val, *reloc_addr, reloc_addr);
287 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
288 unsigned long rel_addr,
289 unsigned long rel_size)
291 (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
295 _dl_parse_relocation_information(struct dyn_elf *rpnt,
296 unsigned long rel_addr,
297 unsigned long rel_size)
299 return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size, _dl_do_reloc);