1 /*
2 * ELF object format helpers - x86:x86
3 *
4 * Copyright (C) 2004-2007 Michael Urman
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND OTHER CONTRIBUTORS ``AS IS''
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR OTHER CONTRIBUTORS BE
19 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
25 * POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <util.h>
29
30 #include <libyasm.h>
31 #define YASM_OBJFMT_ELF_INTERNAL
32 #include "elf.h"
33 #include "elf-machine.h"
34
35 static elf_machine_ssym elf_x86_x86_ssyms[] = {
36 {"plt", ELF_SSYM_SYM_RELATIVE, R_386_PLT32, 32},
37 {"gotoff", 0, R_386_GOTOFF, 32},
38 /* special one for NASM */
39 {"gotpc", ELF_SSYM_CURPOS_ADJUST, R_386_GOTPC, 32},
40 {"tlsgd", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
41 R_386_TLS_GD, 32},
42 {"tlsldm", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
43 R_386_TLS_LDM, 32},
44 {"gottpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
45 R_386_TLS_IE_32, 32},
46 {"tpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
47 R_386_TLS_LE_32, 32},
48 {"ntpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
49 R_386_TLS_LE, 32},
50 {"dtpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
51 R_386_TLS_LDO_32, 32},
52 {"gotntpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
53 R_386_TLS_GOTIE, 32},
54 {"indntpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
55 R_386_TLS_IE, 32},
56 {"got", ELF_SSYM_SYM_RELATIVE, R_386_GOT32, 32},
57 {"tlsdesc", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
58 R_386_TLS_GOTDESC, 32},
59 {"tlscall", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
60 R_386_TLS_DESC_CALL, 32}
61 };
62
63 static int
elf_x86_x86_accepts_reloc(size_t val,yasm_symrec * wrt)64 elf_x86_x86_accepts_reloc(size_t val, yasm_symrec *wrt)
65 {
66 if (wrt) {
67 const elf_machine_ssym *ssym = (elf_machine_ssym *)
68 yasm_symrec_get_data(wrt, &elf_ssym_symrec_data);
69 if (!ssym || val != ssym->size)
70 return 0;
71 return 1;
72 }
73 return (val&(val-1)) ? 0 : ((val & (8|16|32)) != 0);
74 }
75
76 static void
elf_x86_x86_write_symtab_entry(unsigned char * bufp,elf_symtab_entry * entry,yasm_intnum * value_intn,yasm_intnum * size_intn)77 elf_x86_x86_write_symtab_entry(unsigned char *bufp,
78 elf_symtab_entry *entry,
79 yasm_intnum *value_intn,
80 yasm_intnum *size_intn)
81 {
82 YASM_WRITE_32_L(bufp, entry->name ? entry->name->index : 0);
83 YASM_WRITE_32I_L(bufp, value_intn);
84 YASM_WRITE_32I_L(bufp, size_intn);
85
86 YASM_WRITE_8(bufp, ELF32_ST_INFO(entry->bind, entry->type));
87 YASM_WRITE_8(bufp, ELF32_ST_OTHER(entry->vis));
88 if (entry->sect) {
89 elf_secthead *shead =
90 yasm_section_get_data(entry->sect, &elf_section_data);
91 if (!shead)
92 yasm_internal_error(N_("symbol references section without data"));
93 YASM_WRITE_16_L(bufp, shead->index);
94 } else {
95 YASM_WRITE_16_L(bufp, entry->index);
96 }
97 }
98
99 static void
elf_x86_x86_write_secthead(unsigned char * bufp,elf_secthead * shead)100 elf_x86_x86_write_secthead(unsigned char *bufp, elf_secthead *shead)
101 {
102 YASM_WRITE_32_L(bufp, shead->name ? shead->name->index : 0);
103 YASM_WRITE_32_L(bufp, shead->type);
104 YASM_WRITE_32_L(bufp, shead->flags);
105 YASM_WRITE_32_L(bufp, 0); /* vmem address */
106
107 YASM_WRITE_32_L(bufp, shead->offset);
108 YASM_WRITE_32I_L(bufp, shead->size);
109 YASM_WRITE_32_L(bufp, shead->link);
110 YASM_WRITE_32_L(bufp, shead->info);
111
112 YASM_WRITE_32_L(bufp, shead->align);
113 YASM_WRITE_32_L(bufp, shead->entsize);
114
115 }
116
117 static void
elf_x86_x86_write_secthead_rel(unsigned char * bufp,elf_secthead * shead,elf_section_index symtab_idx,elf_section_index sindex)118 elf_x86_x86_write_secthead_rel(unsigned char *bufp,
119 elf_secthead *shead,
120 elf_section_index symtab_idx,
121 elf_section_index sindex)
122 {
123 YASM_WRITE_32_L(bufp, shead->rel_name ? shead->rel_name->index : 0);
124 YASM_WRITE_32_L(bufp, SHT_REL);
125 YASM_WRITE_32_L(bufp, 0);
126 YASM_WRITE_32_L(bufp, 0);
127
128 YASM_WRITE_32_L(bufp, shead->rel_offset);
129 YASM_WRITE_32_L(bufp, RELOC32_SIZE * shead->nreloc);/* size */
130 YASM_WRITE_32_L(bufp, symtab_idx); /* link: symtab index */
131 YASM_WRITE_32_L(bufp, shead->index); /* info: relocated's index */
132
133 YASM_WRITE_32_L(bufp, RELOC32_ALIGN); /* align */
134 YASM_WRITE_32_L(bufp, RELOC32_SIZE); /* entity size */
135 }
136
137 static void
elf_x86_x86_handle_reloc_addend(yasm_intnum * intn,elf_reloc_entry * reloc,unsigned long offset)138 elf_x86_x86_handle_reloc_addend(yasm_intnum *intn,
139 elf_reloc_entry *reloc,
140 unsigned long offset)
141 {
142 if (!reloc->wrt && reloc->is_GOT_sym && reloc->valsize == 32 && offset != 0)
143 {
144 yasm_intnum *off_intn = yasm_intnum_create_uint(offset);
145 yasm_intnum_calc(intn, YASM_EXPR_ADD, off_intn);
146 yasm_intnum_destroy(off_intn);
147 }
148 return; /* .rel: Leave addend in intn */
149 }
150
151 static unsigned int
elf_x86_x86_map_reloc_info_to_type(elf_reloc_entry * reloc)152 elf_x86_x86_map_reloc_info_to_type(elf_reloc_entry *reloc)
153 {
154 if (reloc->wrt) {
155 const elf_machine_ssym *ssym = (elf_machine_ssym *)
156 yasm_symrec_get_data(reloc->wrt, &elf_ssym_symrec_data);
157 if (!ssym || reloc->valsize != ssym->size)
158 yasm_internal_error(N_("Unsupported WRT"));
159
160 /* Force TLS type; this is required by the linker. */
161 if (ssym->sym_rel & ELF_SSYM_THREAD_LOCAL) {
162 elf_symtab_entry *esym;
163
164 esym = yasm_symrec_get_data(reloc->reloc.sym, &elf_symrec_data);
165 if (esym)
166 esym->type = STT_TLS;
167 }
168 return (unsigned char) ssym->reloc;
169 } else if (reloc->is_GOT_sym && reloc->valsize == 32) {
170 return (unsigned char) R_386_GOTPC;
171 } else if (reloc->rtype_rel) {
172 switch (reloc->valsize) {
173 case 8: return (unsigned char) R_386_PC8;
174 case 16: return (unsigned char) R_386_PC16;
175 case 32: return (unsigned char) R_386_PC32;
176 default: yasm_internal_error(N_("Unsupported relocation size"));
177 }
178 } else {
179 switch (reloc->valsize) {
180 case 8: return (unsigned char) R_386_8;
181 case 16: return (unsigned char) R_386_16;
182 case 32: return (unsigned char) R_386_32;
183 default: yasm_internal_error(N_("Unsupported relocation size"));
184 }
185 }
186 return 0;
187 }
188
189 static void
elf_x86_x86_write_reloc(unsigned char * bufp,elf_reloc_entry * reloc,unsigned int r_type,unsigned int r_sym)190 elf_x86_x86_write_reloc(unsigned char *bufp, elf_reloc_entry *reloc,
191 unsigned int r_type, unsigned int r_sym)
192 {
193 YASM_WRITE_32I_L(bufp, reloc->reloc.addr);
194 YASM_WRITE_32_L(bufp, ELF32_R_INFO((unsigned long)r_sym, (unsigned char)r_type));
195 }
196
197 static void
elf_x86_x86_write_proghead(unsigned char ** bufpp,elf_offset secthead_addr,unsigned long secthead_count,elf_section_index shstrtab_index)198 elf_x86_x86_write_proghead(unsigned char **bufpp,
199 elf_offset secthead_addr,
200 unsigned long secthead_count,
201 elf_section_index shstrtab_index)
202 {
203 unsigned char *bufp = *bufpp;
204 unsigned char *buf = bufp-4;
205 YASM_WRITE_8(bufp, ELFCLASS32); /* elf class */
206 YASM_WRITE_8(bufp, ELFDATA2LSB); /* data encoding :: MSB? */
207 YASM_WRITE_8(bufp, EV_CURRENT); /* elf version */
208 while (bufp-buf < EI_NIDENT) /* e_ident padding */
209 YASM_WRITE_8(bufp, 0);
210
211 YASM_WRITE_16_L(bufp, ET_REL); /* e_type - object file */
212 YASM_WRITE_16_L(bufp, EM_386); /* e_machine - or others */
213 YASM_WRITE_32_L(bufp, EV_CURRENT); /* elf version */
214 YASM_WRITE_32_L(bufp, 0); /* e_entry exection startaddr */
215 YASM_WRITE_32_L(bufp, 0); /* e_phoff program header off */
216 YASM_WRITE_32_L(bufp, secthead_addr); /* e_shoff section header off */
217 YASM_WRITE_32_L(bufp, 0); /* e_flags also by arch */
218 YASM_WRITE_16_L(bufp, EHDR32_SIZE); /* e_ehsize */
219 YASM_WRITE_16_L(bufp, 0); /* e_phentsize */
220 YASM_WRITE_16_L(bufp, 0); /* e_phnum */
221 YASM_WRITE_16_L(bufp, SHDR32_SIZE); /* e_shentsize */
222 YASM_WRITE_16_L(bufp, secthead_count); /* e_shnum */
223 YASM_WRITE_16_L(bufp, shstrtab_index); /* e_shstrndx */
224 *bufpp = bufp;
225 }
226
227 const elf_machine_handler
228 elf_machine_handler_x86_x86 = {
229 "x86", "x86", ".rel",
230 SYMTAB32_SIZE, SYMTAB32_ALIGN, RELOC32_SIZE, SHDR32_SIZE, EHDR32_SIZE,
231 elf_x86_x86_accepts_reloc,
232 elf_x86_x86_write_symtab_entry,
233 elf_x86_x86_write_secthead,
234 elf_x86_x86_write_secthead_rel,
235 elf_x86_x86_handle_reloc_addend,
236 elf_x86_x86_map_reloc_info_to_type,
237 elf_x86_x86_write_reloc,
238 elf_x86_x86_write_proghead,
239 elf_x86_x86_ssyms,
240 sizeof(elf_x86_x86_ssyms)/sizeof(elf_x86_x86_ssyms[0]),
241 32
242 };
243