1 /*
2 * ELF object format helpers - x86:amd64
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_amd64_ssyms[] = {
36 {"pltoff", ELF_SSYM_SYM_RELATIVE, R_X86_64_PLTOFF64, 64},
37 {"plt", ELF_SSYM_SYM_RELATIVE, R_X86_64_PLT32, 32},
38 {"gotplt", ELF_SSYM_SYM_RELATIVE, R_X86_64_GOTPLT64, 64},
39 {"gotoff", ELF_SSYM_SYM_RELATIVE, R_X86_64_GOTOFF64, 64},
40 {"gotpcrel", ELF_SSYM_SYM_RELATIVE, R_X86_64_GOTPCREL, 32},
41 {"tlsgd", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
42 R_X86_64_TLSGD, 32},
43 {"tlsld", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
44 R_X86_64_TLSLD, 32},
45 {"gottpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
46 R_X86_64_GOTTPOFF, 32},
47 {"tpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
48 R_X86_64_TPOFF32, 32},
49 {"dtpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
50 R_X86_64_DTPOFF32, 32},
51 {"got", ELF_SSYM_SYM_RELATIVE, R_X86_64_GOT32, 32},
52 {"tlsdesc", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
53 R_X86_64_GOTPC32_TLSDESC, 32},
54 {"tlscall", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
55 R_X86_64_TLSDESC_CALL, 32}
56 };
57
58 static int
elf_x86_amd64_accepts_reloc(size_t val,yasm_symrec * wrt)59 elf_x86_amd64_accepts_reloc(size_t val, yasm_symrec *wrt)
60 {
61 if (wrt) {
62 const elf_machine_ssym *ssym = (elf_machine_ssym *)
63 yasm_symrec_get_data(wrt, &elf_ssym_symrec_data);
64 if (!ssym || val != ssym->size)
65 return 0;
66 return 1;
67 }
68 return (val&(val-1)) ? 0 : ((val & (8|16|32|64)) != 0);
69 }
70
71 static void
elf_x86_amd64_write_symtab_entry(unsigned char * bufp,elf_symtab_entry * entry,yasm_intnum * value_intn,yasm_intnum * size_intn)72 elf_x86_amd64_write_symtab_entry(unsigned char *bufp,
73 elf_symtab_entry *entry,
74 yasm_intnum *value_intn,
75 yasm_intnum *size_intn)
76 {
77 YASM_WRITE_32_L(bufp, entry->name ? entry->name->index : 0);
78 YASM_WRITE_8(bufp, ELF64_ST_INFO(entry->bind, entry->type));
79 YASM_WRITE_8(bufp, ELF64_ST_OTHER(entry->vis));
80 if (entry->sect) {
81 elf_secthead *shead =
82 yasm_section_get_data(entry->sect, &elf_section_data);
83 if (!shead)
84 yasm_internal_error(N_("symbol references section without data"));
85 YASM_WRITE_16_L(bufp, shead->index);
86 } else {
87 YASM_WRITE_16_L(bufp, entry->index);
88 }
89 YASM_WRITE_64I_L(bufp, value_intn);
90 YASM_WRITE_64I_L(bufp, size_intn);
91 }
92
93 static void
elf_x86_amd64_write_secthead(unsigned char * bufp,elf_secthead * shead)94 elf_x86_amd64_write_secthead(unsigned char *bufp, elf_secthead *shead)
95 {
96 YASM_WRITE_32_L(bufp, shead->name ? shead->name->index : 0);
97 YASM_WRITE_32_L(bufp, shead->type);
98 YASM_WRITE_64Z_L(bufp, shead->flags);
99 YASM_WRITE_64Z_L(bufp, 0); /* vmem address */
100 YASM_WRITE_64Z_L(bufp, shead->offset);
101 YASM_WRITE_64I_L(bufp, shead->size);
102
103 YASM_WRITE_32_L(bufp, shead->link);
104 YASM_WRITE_32_L(bufp, shead->info);
105
106 YASM_WRITE_64Z_L(bufp, shead->align);
107 YASM_WRITE_64Z_L(bufp, shead->entsize);
108 }
109
110 static void
elf_x86_amd64_write_secthead_rel(unsigned char * bufp,elf_secthead * shead,elf_section_index symtab_idx,elf_section_index sindex)111 elf_x86_amd64_write_secthead_rel(unsigned char *bufp,
112 elf_secthead *shead,
113 elf_section_index symtab_idx,
114 elf_section_index sindex)
115 {
116 yasm_intnum *nreloc;
117 yasm_intnum *relocsize;
118
119 YASM_WRITE_32_L(bufp, shead->rel_name ? shead->rel_name->index : 0);
120 YASM_WRITE_32_L(bufp, SHT_RELA);
121 YASM_WRITE_64Z_L(bufp, 0);
122 YASM_WRITE_64Z_L(bufp, 0);
123 YASM_WRITE_64Z_L(bufp, shead->rel_offset);
124
125 nreloc = yasm_intnum_create_uint(shead->nreloc);
126 relocsize = yasm_intnum_create_uint(RELOC64A_SIZE);
127 yasm_intnum_calc(relocsize, YASM_EXPR_MUL, nreloc);
128 YASM_WRITE_64I_L(bufp, relocsize); /* size */
129 yasm_intnum_destroy(nreloc);
130 yasm_intnum_destroy(relocsize);
131
132 YASM_WRITE_32_L(bufp, symtab_idx); /* link: symtab index */
133 YASM_WRITE_32_L(bufp, shead->index); /* info: relocated's index */
134 YASM_WRITE_64Z_L(bufp, RELOC64_ALIGN); /* align */
135 YASM_WRITE_64Z_L(bufp, RELOC64A_SIZE); /* entity size */
136 }
137
138 static void
elf_x86_amd64_handle_reloc_addend(yasm_intnum * intn,elf_reloc_entry * reloc,unsigned long offset)139 elf_x86_amd64_handle_reloc_addend(yasm_intnum *intn,
140 elf_reloc_entry *reloc,
141 unsigned long offset)
142 {
143 /* .rela: copy value out as addend, replace original with 0 */
144 reloc->addend = yasm_intnum_copy(intn);
145 yasm_intnum_zero(intn);
146 }
147
148 static unsigned int
elf_x86_amd64_map_reloc_info_to_type(elf_reloc_entry * reloc)149 elf_x86_amd64_map_reloc_info_to_type(elf_reloc_entry *reloc)
150 {
151 if (reloc->wrt) {
152 const elf_machine_ssym *ssym = (elf_machine_ssym *)
153 yasm_symrec_get_data(reloc->wrt, &elf_ssym_symrec_data);
154 if (!ssym || reloc->valsize != ssym->size)
155 yasm_internal_error(N_("Unsupported WRT"));
156
157 /* Force TLS type; this is required by the linker. */
158 if (ssym->sym_rel & ELF_SSYM_THREAD_LOCAL) {
159 elf_symtab_entry *esym;
160
161 esym = yasm_symrec_get_data(reloc->reloc.sym, &elf_symrec_data);
162 if (esym)
163 esym->type = STT_TLS;
164 }
165 /* Map PC-relative GOT to appropriate relocation */
166 if (reloc->rtype_rel && ssym->reloc == R_X86_64_GOT32)
167 return (unsigned char) R_X86_64_GOTPCREL;
168 return (unsigned char) ssym->reloc;
169 } else if (reloc->is_GOT_sym && reloc->valsize == 32) {
170 return (unsigned char) R_X86_64_GOTPC32;
171 } else if (reloc->is_GOT_sym && reloc->valsize == 64) {
172 return (unsigned char) R_X86_64_GOTPC64;
173 } else if (reloc->rtype_rel) {
174 switch (reloc->valsize) {
175 case 8: return (unsigned char) R_X86_64_PC8;
176 case 16: return (unsigned char) R_X86_64_PC16;
177 case 32: return (unsigned char) R_X86_64_PC32;
178 case 64: return (unsigned char) R_X86_64_PC64;
179 default: yasm_internal_error(N_("Unsupported relocation size"));
180 }
181 } else {
182 switch (reloc->valsize) {
183 case 8: return (unsigned char) R_X86_64_8;
184 case 16: return (unsigned char) R_X86_64_16;
185 case 32: return (unsigned char) R_X86_64_32;
186 case 64: return (unsigned char) R_X86_64_64;
187 default: yasm_internal_error(N_("Unsupported relocation size"));
188 }
189 }
190 return 0;
191 }
192
193 static void
elf_x86_amd64_write_reloc(unsigned char * bufp,elf_reloc_entry * reloc,unsigned int r_type,unsigned int r_sym)194 elf_x86_amd64_write_reloc(unsigned char *bufp, elf_reloc_entry *reloc,
195 unsigned int r_type, unsigned int r_sym)
196 {
197 YASM_WRITE_64I_L(bufp, reloc->reloc.addr);
198 /*YASM_WRITE_64_L(bufp, ELF64_R_INFO(r_sym, r_type));*/
199 YASM_WRITE_64C_L(bufp, r_sym, r_type);
200 if (reloc->addend)
201 YASM_WRITE_64I_L(bufp, reloc->addend);
202 else {
203 YASM_WRITE_32_L(bufp, 0);
204 YASM_WRITE_32_L(bufp, 0);
205 }
206 }
207
208 static void
elf_x86_amd64_write_proghead(unsigned char ** bufpp,elf_offset secthead_addr,unsigned long secthead_count,elf_section_index shstrtab_index)209 elf_x86_amd64_write_proghead(unsigned char **bufpp,
210 elf_offset secthead_addr,
211 unsigned long secthead_count,
212 elf_section_index shstrtab_index)
213 {
214 unsigned char *bufp = *bufpp;
215 unsigned char *buf = bufp-4;
216 YASM_WRITE_8(bufp, ELFCLASS64); /* elf class */
217 YASM_WRITE_8(bufp, ELFDATA2LSB); /* data encoding :: MSB? */
218 YASM_WRITE_8(bufp, EV_CURRENT); /* elf version */
219 YASM_WRITE_8(bufp, ELFOSABI_SYSV); /* os/abi */
220 YASM_WRITE_8(bufp, 0); /* SYSV v3 ABI=0 */
221 while (bufp-buf < EI_NIDENT) /* e_ident padding */
222 YASM_WRITE_8(bufp, 0);
223
224 YASM_WRITE_16_L(bufp, ET_REL); /* e_type - object file */
225 YASM_WRITE_16_L(bufp, EM_X86_64); /* e_machine - or others */
226 YASM_WRITE_32_L(bufp, EV_CURRENT); /* elf version */
227 YASM_WRITE_64Z_L(bufp, 0); /* e_entry */
228 YASM_WRITE_64Z_L(bufp, 0); /* e_phoff */
229 YASM_WRITE_64Z_L(bufp, secthead_addr); /* e_shoff secthead off */
230
231 YASM_WRITE_32_L(bufp, 0); /* e_flags */
232 YASM_WRITE_16_L(bufp, EHDR64_SIZE); /* e_ehsize */
233 YASM_WRITE_16_L(bufp, 0); /* e_phentsize */
234 YASM_WRITE_16_L(bufp, 0); /* e_phnum */
235 YASM_WRITE_16_L(bufp, SHDR64_SIZE); /* e_shentsize */
236 YASM_WRITE_16_L(bufp, secthead_count); /* e_shnum */
237 YASM_WRITE_16_L(bufp, shstrtab_index); /* e_shstrndx */
238 *bufpp = bufp;
239 }
240
241 const elf_machine_handler
242 elf_machine_handler_x86_amd64 = {
243 "x86", "amd64", ".rela",
244 SYMTAB64_SIZE, SYMTAB64_ALIGN, RELOC64A_SIZE, SHDR64_SIZE, EHDR64_SIZE,
245 elf_x86_amd64_accepts_reloc,
246 elf_x86_amd64_write_symtab_entry,
247 elf_x86_amd64_write_secthead,
248 elf_x86_amd64_write_secthead_rel,
249 elf_x86_amd64_handle_reloc_addend,
250 elf_x86_amd64_map_reloc_info_to_type,
251 elf_x86_amd64_write_reloc,
252 elf_x86_amd64_write_proghead,
253 elf_x86_amd64_ssyms,
254 sizeof(elf_x86_amd64_ssyms)/sizeof(elf_x86_amd64_ssyms[0]),
255 64
256 };
257