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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// 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}