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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 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 orc->end = 0;
25 orc->sp_reg = ORC_REG_UNDEFINED;
26 return 0;
27 }
28
29 orc->end = cfi->end;
30
31 if (cfi->cfa.base == CFI_UNDEFINED) {
32 orc->sp_reg = ORC_REG_UNDEFINED;
33 return 0;
34 }
35
36 switch (cfi->cfa.base) {
37 case CFI_SP:
38 orc->sp_reg = ORC_REG_SP;
39 break;
40 case CFI_SP_INDIRECT:
41 orc->sp_reg = ORC_REG_SP_INDIRECT;
42 break;
43 case CFI_BP:
44 orc->sp_reg = ORC_REG_BP;
45 break;
46 case CFI_BP_INDIRECT:
47 orc->sp_reg = ORC_REG_BP_INDIRECT;
48 break;
49 case CFI_R10:
50 orc->sp_reg = ORC_REG_R10;
51 break;
52 case CFI_R13:
53 orc->sp_reg = ORC_REG_R13;
54 break;
55 case CFI_DI:
56 orc->sp_reg = ORC_REG_DI;
57 break;
58 case CFI_DX:
59 orc->sp_reg = ORC_REG_DX;
60 break;
61 default:
62 WARN_FUNC("unknown CFA base reg %d",
63 insn->sec, insn->offset, cfi->cfa.base);
64 return -1;
65 }
66
67 switch (bp->base) {
68 case CFI_UNDEFINED:
69 orc->bp_reg = ORC_REG_UNDEFINED;
70 break;
71 case CFI_CFA:
72 orc->bp_reg = ORC_REG_PREV_SP;
73 break;
74 case CFI_BP:
75 orc->bp_reg = ORC_REG_BP;
76 break;
77 default:
78 WARN_FUNC("unknown BP base reg %d",
79 insn->sec, insn->offset, bp->base);
80 return -1;
81 }
82
83 orc->sp_offset = cfi->cfa.offset;
84 orc->bp_offset = bp->offset;
85 orc->type = cfi->type;
86
87 return 0;
88}
89
90static int write_orc_entry(struct elf *elf, struct section *orc_sec,
91 struct section *ip_sec, unsigned int idx,
92 struct section *insn_sec, unsigned long insn_off,
93 struct orc_entry *o)
94{
95 struct orc_entry *orc;
96
97 /* populate ORC data */
98 orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
99 memcpy(orc, o, sizeof(*orc));
100 orc->sp_offset = bswap_if_needed(elf, orc->sp_offset);
101 orc->bp_offset = bswap_if_needed(elf, orc->bp_offset);
102
103 /* populate reloc for ip */
104 if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32,
105 insn_sec, insn_off))
106 return -1;
107
108 return 0;
109}
110
111struct orc_list_entry {
112 struct list_head list;
113 struct orc_entry orc;
114 struct section *insn_sec;
115 unsigned long insn_off;
116};
117
118static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
119 struct section *sec, unsigned long offset)
120{
121 struct orc_list_entry *entry = malloc(sizeof(*entry));
122
123 if (!entry) {
124 WARN("malloc failed");
125 return -1;
126 }
127
128 entry->orc = *orc;
129 entry->insn_sec = sec;
130 entry->insn_off = offset;
131
132 list_add_tail(&entry->list, orc_list);
133 return 0;
134}
135
136static unsigned long alt_group_len(struct alt_group *alt_group)
137{
138 return alt_group->last_insn->offset +
139 alt_group->last_insn->len -
140 alt_group->first_insn->offset;
141}
142
143int orc_create(struct objtool_file *file)
144{
145 struct section *sec, *orc_sec;
146 unsigned int nr = 0, idx = 0;
147 struct orc_list_entry *entry;
148 struct list_head orc_list;
149
150 struct orc_entry null = {
151 .sp_reg = ORC_REG_UNDEFINED,
152 .bp_reg = ORC_REG_UNDEFINED,
153 .type = UNWIND_HINT_TYPE_CALL,
154 };
155
156 /* Build a deduplicated list of ORC entries: */
157 INIT_LIST_HEAD(&orc_list);
158 for_each_sec(file, sec) {
159 struct orc_entry orc, prev_orc = {0};
160 struct instruction *insn;
161 bool empty = true;
162
163 if (!sec->text)
164 continue;
165
166 sec_for_each_insn(file, sec, insn) {
167 struct alt_group *alt_group = insn->alt_group;
168 int i;
169
170 if (!alt_group) {
171 if (init_orc_entry(&orc, insn->cfi, insn))
172 return -1;
173 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
174 continue;
175 if (orc_list_add(&orc_list, &orc, sec,
176 insn->offset))
177 return -1;
178 nr++;
179 prev_orc = orc;
180 empty = false;
181 continue;
182 }
183
184 /*
185 * Alternatives can have different stack layout
186 * possibilities (but they shouldn't conflict).
187 * Instead of traversing the instructions, use the
188 * alt_group's flattened byte-offset-addressed CFI
189 * array.
190 */
191 for (i = 0; i < alt_group_len(alt_group); i++) {
192 struct cfi_state *cfi = alt_group->cfi[i];
193 if (!cfi)
194 continue;
195 /* errors are reported on the original insn */
196 if (init_orc_entry(&orc, cfi, insn))
197 return -1;
198 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
199 continue;
200 if (orc_list_add(&orc_list, &orc, insn->sec,
201 insn->offset + i))
202 return -1;
203 nr++;
204 prev_orc = orc;
205 empty = false;
206 }
207
208 /* Skip to the end of the alt_group */
209 insn = alt_group->last_insn;
210 }
211
212 /* Add a section terminator */
213 if (!empty) {
214 orc_list_add(&orc_list, &null, sec, sec->sh.sh_size);
215 nr++;
216 }
217 }
218 if (!nr)
219 return 0;
220
221 /* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
222 sec = find_section_by_name(file->elf, ".orc_unwind");
223 if (sec) {
224 WARN("file already has .orc_unwind section, skipping");
225 return -1;
226 }
227 orc_sec = elf_create_section(file->elf, ".orc_unwind", 0,
228 sizeof(struct orc_entry), nr);
229 if (!orc_sec)
230 return -1;
231
232 sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr);
233 if (!sec)
234 return -1;
235
236 /* Write ORC entries to sections: */
237 list_for_each_entry(entry, &orc_list, list) {
238 if (write_orc_entry(file->elf, orc_sec, sec, idx++,
239 entry->insn_sec, entry->insn_off,
240 &entry->orc))
241 return -1;
242 }
243
244 return 0;
245}
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 "check.h"
10#include "warn.h"
11
12int create_orc(struct objtool_file *file)
13{
14 struct instruction *insn;
15
16 for_each_insn(file, insn) {
17 struct orc_entry *orc = &insn->orc;
18 struct cfi_reg *cfa = &insn->cfi.cfa;
19 struct cfi_reg *bp = &insn->cfi.regs[CFI_BP];
20
21 orc->end = insn->cfi.end;
22
23 if (cfa->base == CFI_UNDEFINED) {
24 orc->sp_reg = ORC_REG_UNDEFINED;
25 continue;
26 }
27
28 switch (cfa->base) {
29 case CFI_SP:
30 orc->sp_reg = ORC_REG_SP;
31 break;
32 case CFI_SP_INDIRECT:
33 orc->sp_reg = ORC_REG_SP_INDIRECT;
34 break;
35 case CFI_BP:
36 orc->sp_reg = ORC_REG_BP;
37 break;
38 case CFI_BP_INDIRECT:
39 orc->sp_reg = ORC_REG_BP_INDIRECT;
40 break;
41 case CFI_R10:
42 orc->sp_reg = ORC_REG_R10;
43 break;
44 case CFI_R13:
45 orc->sp_reg = ORC_REG_R13;
46 break;
47 case CFI_DI:
48 orc->sp_reg = ORC_REG_DI;
49 break;
50 case CFI_DX:
51 orc->sp_reg = ORC_REG_DX;
52 break;
53 default:
54 WARN_FUNC("unknown CFA base reg %d",
55 insn->sec, insn->offset, cfa->base);
56 return -1;
57 }
58
59 switch(bp->base) {
60 case CFI_UNDEFINED:
61 orc->bp_reg = ORC_REG_UNDEFINED;
62 break;
63 case CFI_CFA:
64 orc->bp_reg = ORC_REG_PREV_SP;
65 break;
66 case CFI_BP:
67 orc->bp_reg = ORC_REG_BP;
68 break;
69 default:
70 WARN_FUNC("unknown BP base reg %d",
71 insn->sec, insn->offset, bp->base);
72 return -1;
73 }
74
75 orc->sp_offset = cfa->offset;
76 orc->bp_offset = bp->offset;
77 orc->type = insn->cfi.type;
78 }
79
80 return 0;
81}
82
83static int create_orc_entry(struct elf *elf, struct section *u_sec, struct section *ip_relocsec,
84 unsigned int idx, struct section *insn_sec,
85 unsigned long insn_off, struct orc_entry *o)
86{
87 struct orc_entry *orc;
88 struct reloc *reloc;
89
90 /* populate ORC data */
91 orc = (struct orc_entry *)u_sec->data->d_buf + idx;
92 memcpy(orc, o, sizeof(*orc));
93
94 /* populate reloc for ip */
95 reloc = malloc(sizeof(*reloc));
96 if (!reloc) {
97 perror("malloc");
98 return -1;
99 }
100 memset(reloc, 0, sizeof(*reloc));
101
102 if (insn_sec->sym) {
103 reloc->sym = insn_sec->sym;
104 reloc->addend = insn_off;
105 } else {
106 /*
107 * The Clang assembler doesn't produce section symbols, so we
108 * have to reference the function symbol instead:
109 */
110 reloc->sym = find_symbol_containing(insn_sec, insn_off);
111 if (!reloc->sym) {
112 /*
113 * Hack alert. This happens when we need to reference
114 * the NOP pad insn immediately after the function.
115 */
116 reloc->sym = find_symbol_containing(insn_sec,
117 insn_off - 1);
118 }
119 if (!reloc->sym) {
120 WARN("missing symbol for insn at offset 0x%lx\n",
121 insn_off);
122 return -1;
123 }
124
125 reloc->addend = insn_off - reloc->sym->offset;
126 }
127
128 reloc->type = R_X86_64_PC32;
129 reloc->offset = idx * sizeof(int);
130 reloc->sec = ip_relocsec;
131
132 elf_add_reloc(elf, reloc);
133
134 return 0;
135}
136
137int create_orc_sections(struct objtool_file *file)
138{
139 struct instruction *insn, *prev_insn;
140 struct section *sec, *u_sec, *ip_relocsec;
141 unsigned int idx;
142
143 struct orc_entry empty = {
144 .sp_reg = ORC_REG_UNDEFINED,
145 .bp_reg = ORC_REG_UNDEFINED,
146 .type = ORC_TYPE_CALL,
147 };
148
149 sec = find_section_by_name(file->elf, ".orc_unwind");
150 if (sec) {
151 WARN("file already has .orc_unwind section, skipping");
152 return -1;
153 }
154
155 /* count the number of needed orcs */
156 idx = 0;
157 for_each_sec(file, sec) {
158 if (!sec->text)
159 continue;
160
161 prev_insn = NULL;
162 sec_for_each_insn(file, sec, insn) {
163 if (!prev_insn ||
164 memcmp(&insn->orc, &prev_insn->orc,
165 sizeof(struct orc_entry))) {
166 idx++;
167 }
168 prev_insn = insn;
169 }
170
171 /* section terminator */
172 if (prev_insn)
173 idx++;
174 }
175 if (!idx)
176 return -1;
177
178
179 /* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
180 sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
181 if (!sec)
182 return -1;
183
184 ip_relocsec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
185 if (!ip_relocsec)
186 return -1;
187
188 /* create .orc_unwind section */
189 u_sec = elf_create_section(file->elf, ".orc_unwind",
190 sizeof(struct orc_entry), idx);
191
192 /* populate sections */
193 idx = 0;
194 for_each_sec(file, sec) {
195 if (!sec->text)
196 continue;
197
198 prev_insn = NULL;
199 sec_for_each_insn(file, sec, insn) {
200 if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
201 sizeof(struct orc_entry))) {
202
203 if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx,
204 insn->sec, insn->offset,
205 &insn->orc))
206 return -1;
207
208 idx++;
209 }
210 prev_insn = insn;
211 }
212
213 /* section terminator */
214 if (prev_insn) {
215 if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx,
216 prev_insn->sec,
217 prev_insn->offset + prev_insn->len,
218 &empty))
219 return -1;
220
221 idx++;
222 }
223 }
224
225 if (elf_rebuild_reloc_section(file->elf, ip_relocsec))
226 return -1;
227
228 return 0;
229}