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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
4 */
5
6#include <stdlib.h>
7#include <string.h>
8
9#include <linux/objtool_types.h>
10#include <asm/orc_types.h>
11
12#include <objtool/check.h>
13#include <objtool/warn.h>
14#include <objtool/endianness.h>
15
16static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi,
17 struct instruction *insn)
18{
19 struct cfi_reg *bp = &cfi->regs[CFI_BP];
20
21 memset(orc, 0, sizeof(*orc));
22
23 if (!cfi) {
24 /*
25 * This is usually either unreachable nops/traps (which don't
26 * trigger unreachable instruction warnings), or
27 * STACK_FRAME_NON_STANDARD functions.
28 */
29 orc->type = ORC_TYPE_UNDEFINED;
30 return 0;
31 }
32
33 switch (cfi->type) {
34 case UNWIND_HINT_TYPE_UNDEFINED:
35 orc->type = ORC_TYPE_UNDEFINED;
36 return 0;
37 case UNWIND_HINT_TYPE_END_OF_STACK:
38 orc->type = ORC_TYPE_END_OF_STACK;
39 return 0;
40 case UNWIND_HINT_TYPE_CALL:
41 orc->type = ORC_TYPE_CALL;
42 break;
43 case UNWIND_HINT_TYPE_REGS:
44 orc->type = ORC_TYPE_REGS;
45 break;
46 case UNWIND_HINT_TYPE_REGS_PARTIAL:
47 orc->type = ORC_TYPE_REGS_PARTIAL;
48 break;
49 default:
50 WARN_INSN(insn, "unknown unwind hint type %d", cfi->type);
51 return -1;
52 }
53
54 orc->signal = cfi->signal;
55
56 switch (cfi->cfa.base) {
57 case CFI_SP:
58 orc->sp_reg = ORC_REG_SP;
59 break;
60 case CFI_SP_INDIRECT:
61 orc->sp_reg = ORC_REG_SP_INDIRECT;
62 break;
63 case CFI_BP:
64 orc->sp_reg = ORC_REG_BP;
65 break;
66 case CFI_BP_INDIRECT:
67 orc->sp_reg = ORC_REG_BP_INDIRECT;
68 break;
69 case CFI_R10:
70 orc->sp_reg = ORC_REG_R10;
71 break;
72 case CFI_R13:
73 orc->sp_reg = ORC_REG_R13;
74 break;
75 case CFI_DI:
76 orc->sp_reg = ORC_REG_DI;
77 break;
78 case CFI_DX:
79 orc->sp_reg = ORC_REG_DX;
80 break;
81 default:
82 WARN_INSN(insn, "unknown CFA base reg %d", cfi->cfa.base);
83 return -1;
84 }
85
86 switch (bp->base) {
87 case CFI_UNDEFINED:
88 orc->bp_reg = ORC_REG_UNDEFINED;
89 break;
90 case CFI_CFA:
91 orc->bp_reg = ORC_REG_PREV_SP;
92 break;
93 case CFI_BP:
94 orc->bp_reg = ORC_REG_BP;
95 break;
96 default:
97 WARN_INSN(insn, "unknown BP base reg %d", bp->base);
98 return -1;
99 }
100
101 orc->sp_offset = cfi->cfa.offset;
102 orc->bp_offset = bp->offset;
103
104 return 0;
105}
106
107static int write_orc_entry(struct elf *elf, struct section *orc_sec,
108 struct section *ip_sec, unsigned int idx,
109 struct section *insn_sec, unsigned long insn_off,
110 struct orc_entry *o)
111{
112 struct orc_entry *orc;
113
114 /* populate ORC data */
115 orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
116 memcpy(orc, o, sizeof(*orc));
117 orc->sp_offset = bswap_if_needed(elf, orc->sp_offset);
118 orc->bp_offset = bswap_if_needed(elf, orc->bp_offset);
119
120 /* populate reloc for ip */
121 if (!elf_init_reloc_text_sym(elf, ip_sec, idx * sizeof(int), idx,
122 insn_sec, insn_off))
123 return -1;
124
125 return 0;
126}
127
128struct orc_list_entry {
129 struct list_head list;
130 struct orc_entry orc;
131 struct section *insn_sec;
132 unsigned long insn_off;
133};
134
135static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
136 struct section *sec, unsigned long offset)
137{
138 struct orc_list_entry *entry = malloc(sizeof(*entry));
139
140 if (!entry) {
141 WARN("malloc failed");
142 return -1;
143 }
144
145 entry->orc = *orc;
146 entry->insn_sec = sec;
147 entry->insn_off = offset;
148
149 list_add_tail(&entry->list, orc_list);
150 return 0;
151}
152
153static unsigned long alt_group_len(struct alt_group *alt_group)
154{
155 return alt_group->last_insn->offset +
156 alt_group->last_insn->len -
157 alt_group->first_insn->offset;
158}
159
160int orc_create(struct objtool_file *file)
161{
162 struct section *sec, *orc_sec;
163 unsigned int nr = 0, idx = 0;
164 struct orc_list_entry *entry;
165 struct list_head orc_list;
166
167 struct orc_entry null = { .type = ORC_TYPE_UNDEFINED };
168
169 /* Build a deduplicated list of ORC entries: */
170 INIT_LIST_HEAD(&orc_list);
171 for_each_sec(file, sec) {
172 struct orc_entry orc, prev_orc = {0};
173 struct instruction *insn;
174 bool empty = true;
175
176 if (!sec->text)
177 continue;
178
179 sec_for_each_insn(file, sec, insn) {
180 struct alt_group *alt_group = insn->alt_group;
181 int i;
182
183 if (!alt_group) {
184 if (init_orc_entry(&orc, insn->cfi, insn))
185 return -1;
186 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
187 continue;
188 if (orc_list_add(&orc_list, &orc, sec,
189 insn->offset))
190 return -1;
191 nr++;
192 prev_orc = orc;
193 empty = false;
194 continue;
195 }
196
197 /*
198 * Alternatives can have different stack layout
199 * possibilities (but they shouldn't conflict).
200 * Instead of traversing the instructions, use the
201 * alt_group's flattened byte-offset-addressed CFI
202 * array.
203 */
204 for (i = 0; i < alt_group_len(alt_group); i++) {
205 struct cfi_state *cfi = alt_group->cfi[i];
206 if (!cfi)
207 continue;
208 /* errors are reported on the original insn */
209 if (init_orc_entry(&orc, cfi, insn))
210 return -1;
211 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
212 continue;
213 if (orc_list_add(&orc_list, &orc, insn->sec,
214 insn->offset + i))
215 return -1;
216 nr++;
217 prev_orc = orc;
218 empty = false;
219 }
220
221 /* Skip to the end of the alt_group */
222 insn = alt_group->last_insn;
223 }
224
225 /* Add a section terminator */
226 if (!empty) {
227 orc_list_add(&orc_list, &null, sec, sec->sh.sh_size);
228 nr++;
229 }
230 }
231 if (!nr)
232 return 0;
233
234 /* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
235 sec = find_section_by_name(file->elf, ".orc_unwind");
236 if (sec) {
237 WARN("file already has .orc_unwind section, skipping");
238 return -1;
239 }
240 orc_sec = elf_create_section(file->elf, ".orc_unwind",
241 sizeof(struct orc_entry), nr);
242 if (!orc_sec)
243 return -1;
244
245 sec = elf_create_section_pair(file->elf, ".orc_unwind_ip", sizeof(int), nr, nr);
246 if (!sec)
247 return -1;
248
249 /* Write ORC entries to sections: */
250 list_for_each_entry(entry, &orc_list, list) {
251 if (write_orc_entry(file->elf, orc_sec, sec, idx++,
252 entry->insn_sec, entry->insn_off,
253 &entry->orc))
254 return -1;
255 }
256
257 return 0;
258}
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
25int 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 if (cfa->base == CFI_UNDEFINED) {
35 orc->sp_reg = ORC_REG_UNDEFINED;
36 continue;
37 }
38
39 switch (cfa->base) {
40 case CFI_SP:
41 orc->sp_reg = ORC_REG_SP;
42 break;
43 case CFI_SP_INDIRECT:
44 orc->sp_reg = ORC_REG_SP_INDIRECT;
45 break;
46 case CFI_BP:
47 orc->sp_reg = ORC_REG_BP;
48 break;
49 case CFI_BP_INDIRECT:
50 orc->sp_reg = ORC_REG_BP_INDIRECT;
51 break;
52 case CFI_R10:
53 orc->sp_reg = ORC_REG_R10;
54 break;
55 case CFI_R13:
56 orc->sp_reg = ORC_REG_R13;
57 break;
58 case CFI_DI:
59 orc->sp_reg = ORC_REG_DI;
60 break;
61 case CFI_DX:
62 orc->sp_reg = ORC_REG_DX;
63 break;
64 default:
65 WARN_FUNC("unknown CFA base reg %d",
66 insn->sec, insn->offset, cfa->base);
67 return -1;
68 }
69
70 switch(bp->base) {
71 case CFI_UNDEFINED:
72 orc->bp_reg = ORC_REG_UNDEFINED;
73 break;
74 case CFI_CFA:
75 orc->bp_reg = ORC_REG_PREV_SP;
76 break;
77 case CFI_BP:
78 orc->bp_reg = ORC_REG_BP;
79 break;
80 default:
81 WARN_FUNC("unknown BP base reg %d",
82 insn->sec, insn->offset, bp->base);
83 return -1;
84 }
85
86 orc->sp_offset = cfa->offset;
87 orc->bp_offset = bp->offset;
88 orc->type = insn->state.type;
89 }
90
91 return 0;
92}
93
94static int create_orc_entry(struct section *u_sec, struct section *ip_relasec,
95 unsigned int idx, struct section *insn_sec,
96 unsigned long insn_off, struct orc_entry *o)
97{
98 struct orc_entry *orc;
99 struct rela *rela;
100
101 if (!insn_sec->sym) {
102 WARN("missing symbol for section %s", insn_sec->name);
103 return -1;
104 }
105
106 /* populate ORC data */
107 orc = (struct orc_entry *)u_sec->data->d_buf + idx;
108 memcpy(orc, o, sizeof(*orc));
109
110 /* populate rela for ip */
111 rela = malloc(sizeof(*rela));
112 if (!rela) {
113 perror("malloc");
114 return -1;
115 }
116 memset(rela, 0, sizeof(*rela));
117
118 rela->sym = insn_sec->sym;
119 rela->addend = insn_off;
120 rela->type = R_X86_64_PC32;
121 rela->offset = idx * sizeof(int);
122
123 list_add_tail(&rela->list, &ip_relasec->rela_list);
124 hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset);
125
126 return 0;
127}
128
129int create_orc_sections(struct objtool_file *file)
130{
131 struct instruction *insn, *prev_insn;
132 struct section *sec, *u_sec, *ip_relasec;
133 unsigned int idx;
134
135 struct orc_entry empty = {
136 .sp_reg = ORC_REG_UNDEFINED,
137 .bp_reg = ORC_REG_UNDEFINED,
138 .type = ORC_TYPE_CALL,
139 };
140
141 sec = find_section_by_name(file->elf, ".orc_unwind");
142 if (sec) {
143 WARN("file already has .orc_unwind section, skipping");
144 return -1;
145 }
146
147 /* count the number of needed orcs */
148 idx = 0;
149 for_each_sec(file, sec) {
150 if (!sec->text)
151 continue;
152
153 prev_insn = NULL;
154 sec_for_each_insn(file, sec, insn) {
155 if (!prev_insn ||
156 memcmp(&insn->orc, &prev_insn->orc,
157 sizeof(struct orc_entry))) {
158 idx++;
159 }
160 prev_insn = insn;
161 }
162
163 /* section terminator */
164 if (prev_insn)
165 idx++;
166 }
167 if (!idx)
168 return -1;
169
170
171 /* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
172 sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
173 if (!sec)
174 return -1;
175
176 ip_relasec = elf_create_rela_section(file->elf, sec);
177 if (!ip_relasec)
178 return -1;
179
180 /* create .orc_unwind section */
181 u_sec = elf_create_section(file->elf, ".orc_unwind",
182 sizeof(struct orc_entry), idx);
183
184 /* populate sections */
185 idx = 0;
186 for_each_sec(file, sec) {
187 if (!sec->text)
188 continue;
189
190 prev_insn = NULL;
191 sec_for_each_insn(file, sec, insn) {
192 if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
193 sizeof(struct orc_entry))) {
194
195 if (create_orc_entry(u_sec, ip_relasec, idx,
196 insn->sec, insn->offset,
197 &insn->orc))
198 return -1;
199
200 idx++;
201 }
202 prev_insn = insn;
203 }
204
205 /* section terminator */
206 if (prev_insn) {
207 if (create_orc_entry(u_sec, ip_relasec, idx,
208 prev_insn->sec,
209 prev_insn->offset + prev_insn->len,
210 &empty))
211 return -1;
212
213 idx++;
214 }
215 }
216
217 if (elf_rebuild_rela_section(ip_relasec))
218 return -1;
219
220 return 0;
221}