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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.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{
18 struct instruction *insn = container_of(cfi, struct instruction, cfi);
19 struct cfi_reg *bp = &cfi->regs[CFI_BP];
20
21 memset(orc, 0, sizeof(*orc));
22
23 orc->end = cfi->end;
24
25 if (cfi->cfa.base == CFI_UNDEFINED) {
26 orc->sp_reg = ORC_REG_UNDEFINED;
27 return 0;
28 }
29
30 switch (cfi->cfa.base) {
31 case CFI_SP:
32 orc->sp_reg = ORC_REG_SP;
33 break;
34 case CFI_SP_INDIRECT:
35 orc->sp_reg = ORC_REG_SP_INDIRECT;
36 break;
37 case CFI_BP:
38 orc->sp_reg = ORC_REG_BP;
39 break;
40 case CFI_BP_INDIRECT:
41 orc->sp_reg = ORC_REG_BP_INDIRECT;
42 break;
43 case CFI_R10:
44 orc->sp_reg = ORC_REG_R10;
45 break;
46 case CFI_R13:
47 orc->sp_reg = ORC_REG_R13;
48 break;
49 case CFI_DI:
50 orc->sp_reg = ORC_REG_DI;
51 break;
52 case CFI_DX:
53 orc->sp_reg = ORC_REG_DX;
54 break;
55 default:
56 WARN_FUNC("unknown CFA base reg %d",
57 insn->sec, insn->offset, cfi->cfa.base);
58 return -1;
59 }
60
61 switch (bp->base) {
62 case CFI_UNDEFINED:
63 orc->bp_reg = ORC_REG_UNDEFINED;
64 break;
65 case CFI_CFA:
66 orc->bp_reg = ORC_REG_PREV_SP;
67 break;
68 case CFI_BP:
69 orc->bp_reg = ORC_REG_BP;
70 break;
71 default:
72 WARN_FUNC("unknown BP base reg %d",
73 insn->sec, insn->offset, bp->base);
74 return -1;
75 }
76
77 orc->sp_offset = cfi->cfa.offset;
78 orc->bp_offset = bp->offset;
79 orc->type = cfi->type;
80
81 return 0;
82}
83
84static int write_orc_entry(struct elf *elf, struct section *orc_sec,
85 struct section *ip_sec, unsigned int idx,
86 struct section *insn_sec, unsigned long insn_off,
87 struct orc_entry *o)
88{
89 struct orc_entry *orc;
90
91 /* populate ORC data */
92 orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
93 memcpy(orc, o, sizeof(*orc));
94 orc->sp_offset = bswap_if_needed(orc->sp_offset);
95 orc->bp_offset = bswap_if_needed(orc->bp_offset);
96
97 /* populate reloc for ip */
98 if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32,
99 insn_sec, insn_off))
100 return -1;
101
102 return 0;
103}
104
105struct orc_list_entry {
106 struct list_head list;
107 struct orc_entry orc;
108 struct section *insn_sec;
109 unsigned long insn_off;
110};
111
112static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
113 struct section *sec, unsigned long offset)
114{
115 struct orc_list_entry *entry = malloc(sizeof(*entry));
116
117 if (!entry) {
118 WARN("malloc failed");
119 return -1;
120 }
121
122 entry->orc = *orc;
123 entry->insn_sec = sec;
124 entry->insn_off = offset;
125
126 list_add_tail(&entry->list, orc_list);
127 return 0;
128}
129
130static unsigned long alt_group_len(struct alt_group *alt_group)
131{
132 return alt_group->last_insn->offset +
133 alt_group->last_insn->len -
134 alt_group->first_insn->offset;
135}
136
137int orc_create(struct objtool_file *file)
138{
139 struct section *sec, *orc_sec;
140 unsigned int nr = 0, idx = 0;
141 struct orc_list_entry *entry;
142 struct list_head orc_list;
143
144 struct orc_entry null = {
145 .sp_reg = ORC_REG_UNDEFINED,
146 .bp_reg = ORC_REG_UNDEFINED,
147 .type = UNWIND_HINT_TYPE_CALL,
148 };
149
150 /* Build a deduplicated list of ORC entries: */
151 INIT_LIST_HEAD(&orc_list);
152 for_each_sec(file, sec) {
153 struct orc_entry orc, prev_orc = {0};
154 struct instruction *insn;
155 bool empty = true;
156
157 if (!sec->text)
158 continue;
159
160 sec_for_each_insn(file, sec, insn) {
161 struct alt_group *alt_group = insn->alt_group;
162 int i;
163
164 if (!alt_group) {
165 if (init_orc_entry(&orc, &insn->cfi))
166 return -1;
167 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
168 continue;
169 if (orc_list_add(&orc_list, &orc, sec,
170 insn->offset))
171 return -1;
172 nr++;
173 prev_orc = orc;
174 empty = false;
175 continue;
176 }
177
178 /*
179 * Alternatives can have different stack layout
180 * possibilities (but they shouldn't conflict).
181 * Instead of traversing the instructions, use the
182 * alt_group's flattened byte-offset-addressed CFI
183 * array.
184 */
185 for (i = 0; i < alt_group_len(alt_group); i++) {
186 struct cfi_state *cfi = alt_group->cfi[i];
187 if (!cfi)
188 continue;
189 if (init_orc_entry(&orc, cfi))
190 return -1;
191 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
192 continue;
193 if (orc_list_add(&orc_list, &orc, insn->sec,
194 insn->offset + i))
195 return -1;
196 nr++;
197 prev_orc = orc;
198 empty = false;
199 }
200
201 /* Skip to the end of the alt_group */
202 insn = alt_group->last_insn;
203 }
204
205 /* Add a section terminator */
206 if (!empty) {
207 orc_list_add(&orc_list, &null, sec, sec->len);
208 nr++;
209 }
210 }
211 if (!nr)
212 return 0;
213
214 /* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
215 sec = find_section_by_name(file->elf, ".orc_unwind");
216 if (sec) {
217 WARN("file already has .orc_unwind section, skipping");
218 return -1;
219 }
220 orc_sec = elf_create_section(file->elf, ".orc_unwind", 0,
221 sizeof(struct orc_entry), nr);
222 if (!orc_sec)
223 return -1;
224
225 sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr);
226 if (!sec)
227 return -1;
228
229 /* Write ORC entries to sections: */
230 list_for_each_entry(entry, &orc_list, list) {
231 if (write_orc_entry(file->elf, orc_sec, sec, idx++,
232 entry->insn_sec, entry->insn_off,
233 &entry->orc))
234 return -1;
235 }
236
237 return 0;
238}
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}