1 /*
2 * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
16 */
17
18 #include <stdlib.h>
19 #include <string.h>
20
21 #include "orc.h"
22 #include "check.h"
23 #include "warn.h"
24
25 int create_orc(struct objtool_file *file)
26 {
27 struct instruction *insn;
28
29 for_each_insn(file, insn) {
30 struct orc_entry *orc = &insn->orc;
31 struct cfi_reg *cfa = &insn->state.cfa;
32 struct cfi_reg *bp = &insn->state.regs[CFI_BP];
33
34 orc->end = insn->state.end;
35
36 if (cfa->base == CFI_UNDEFINED) {
37 orc->sp_reg = ORC_REG_UNDEFINED;
38 continue;
39 }
40
41 switch (cfa->base) {
42 case CFI_SP:
43 orc->sp_reg = ORC_REG_SP;
44 break;
45 case CFI_SP_INDIRECT:
46 orc->sp_reg = ORC_REG_SP_INDIRECT;
47 break;
48 case CFI_BP:
49 orc->sp_reg = ORC_REG_BP;
50 break;
51 case CFI_BP_INDIRECT:
52 orc->sp_reg = ORC_REG_BP_INDIRECT;
53 break;
54 case CFI_R10:
55 orc->sp_reg = ORC_REG_R10;
56 break;
57 case CFI_R13:
58 orc->sp_reg = ORC_REG_R13;
59 break;
60 case CFI_DI:
61 orc->sp_reg = ORC_REG_DI;
62 break;
63 case CFI_DX:
64 orc->sp_reg = ORC_REG_DX;
65 break;
66 default:
67 WARN_FUNC("unknown CFA base reg %d",
68 insn->sec, insn->offset, cfa->base);
69 return -1;
70 }
71
72 switch(bp->base) {
73 case CFI_UNDEFINED:
74 orc->bp_reg = ORC_REG_UNDEFINED;
75 break;
76 case CFI_CFA:
77 orc->bp_reg = ORC_REG_PREV_SP;
78 break;
79 case CFI_BP:
80 orc->bp_reg = ORC_REG_BP;
81 break;
82 default:
83 WARN_FUNC("unknown BP base reg %d",
84 insn->sec, insn->offset, bp->base);
85 return -1;
86 }
87
88 orc->sp_offset = cfa->offset;
89 orc->bp_offset = bp->offset;
90 orc->type = insn->state.type;
91 }
92
93 return 0;
94 }
95
96 static int create_orc_entry(struct section *u_sec, struct section *ip_relasec,
97 unsigned int idx, struct section *insn_sec,
98 unsigned long insn_off, struct orc_entry *o)
99 {
100 struct orc_entry *orc;
101 struct rela *rela;
102
103 if (!insn_sec->sym) {
104 WARN("missing symbol for section %s", insn_sec->name);
105 return -1;
106 }
107
108 /* populate ORC data */
109 orc = (struct orc_entry *)u_sec->data->d_buf + idx;
110 memcpy(orc, o, sizeof(*orc));
111
112 /* populate rela for ip */
113 rela = malloc(sizeof(*rela));
114 if (!rela) {
115 perror("malloc");
116 return -1;
117 }
118 memset(rela, 0, sizeof(*rela));
119
120 rela->sym = insn_sec->sym;
121 rela->addend = insn_off;
122 rela->type = R_X86_64_PC32;
123 rela->offset = idx * sizeof(int);
124
125 list_add_tail(&rela->list, &ip_relasec->rela_list);
126 hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset);
127
128 return 0;
129 }
130
131 int create_orc_sections(struct objtool_file *file)
132 {
133 struct instruction *insn, *prev_insn;
134 struct section *sec, *u_sec, *ip_relasec;
135 unsigned int idx;
136
137 struct orc_entry empty = {
138 .sp_reg = ORC_REG_UNDEFINED,
139 .bp_reg = ORC_REG_UNDEFINED,
140 .type = ORC_TYPE_CALL,
141 };
142
143 sec = find_section_by_name(file->elf, ".orc_unwind");
144 if (sec) {
145 WARN("file already has .orc_unwind section, skipping");
146 return -1;
147 }
148
149 /* count the number of needed orcs */
150 idx = 0;
151 for_each_sec(file, sec) {
152 if (!sec->text)
153 continue;
154
155 prev_insn = NULL;
156 sec_for_each_insn(file, sec, insn) {
157 if (!prev_insn ||
158 memcmp(&insn->orc, &prev_insn->orc,
159 sizeof(struct orc_entry))) {
160 idx++;
161 }
162 prev_insn = insn;
163 }
164
165 /* section terminator */
166 if (prev_insn)
167 idx++;
168 }
169 if (!idx)
170 return -1;
171
172
173 /* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
174 sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
175 if (!sec)
176 return -1;
177
178 ip_relasec = elf_create_rela_section(file->elf, sec);
179 if (!ip_relasec)
180 return -1;
181
182 /* create .orc_unwind section */
183 u_sec = elf_create_section(file->elf, ".orc_unwind",
184 sizeof(struct orc_entry), idx);
185
186 /* populate sections */
187 idx = 0;
188 for_each_sec(file, sec) {
189 if (!sec->text)
190 continue;
191
192 prev_insn = NULL;
193 sec_for_each_insn(file, sec, insn) {
194 if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
195 sizeof(struct orc_entry))) {
196
197 if (create_orc_entry(u_sec, ip_relasec, idx,
198 insn->sec, insn->offset,
199 &insn->orc))
200 return -1;
201
202 idx++;
203 }
204 prev_insn = insn;
205 }
206
207 /* section terminator */
208 if (prev_insn) {
209 if (create_orc_entry(u_sec, ip_relasec, idx,
210 prev_insn->sec,
211 prev_insn->offset + prev_insn->len,
212 &empty))
213 return -1;
214
215 idx++;
216 }
217 }
218
219 if (elf_rebuild_rela_section(ip_relasec))
220 return -1;
221
222 return 0;
223 }
224
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