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Thomas Gleixner1ccea772019-05-19 15:51:43 +02001// SPDX-License-Identifier: GPL-2.0-or-later
Josh Poimboeuf627fce12017-07-11 10:33:42 -05002/*
3 * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
Josh Poimboeuf627fce12017-07-11 10:33:42 -05004 */
5
6#include <stdlib.h>
7#include <string.h>
8
Josh Poimboeuf627fce12017-07-11 10:33:42 -05009#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;
Peter Zijlstrae7c02192020-03-25 14:04:45 +010018 struct cfi_reg *cfa = &insn->cfi.cfa;
19 struct cfi_reg *bp = &insn->cfi.regs[CFI_BP];
Josh Poimboeuf627fce12017-07-11 10:33:42 -050020
Peter Zijlstrae7c02192020-03-25 14:04:45 +010021 orc->end = insn->cfi.end;
Josh Poimboeufd31a5802018-05-18 08:47:12 +020022
Josh Poimboeuf627fce12017-07-11 10:33:42 -050023 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;
Peter Zijlstrae7c02192020-03-25 14:04:45 +010077 orc->type = insn->cfi.type;
Josh Poimboeuf627fce12017-07-11 10:33:42 -050078 }
79
80 return 0;
81}
82
Peter Zijlstra8b5fa6b2020-03-12 11:23:36 +010083static int create_orc_entry(struct elf *elf, struct section *u_sec, struct section *ip_relasec,
Josh Poimboeuf627fce12017-07-11 10:33:42 -050084 unsigned int idx, struct section *insn_sec,
85 unsigned long insn_off, struct orc_entry *o)
86{
87 struct orc_entry *orc;
88 struct rela *rela;
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 rela for ip */
95 rela = malloc(sizeof(*rela));
96 if (!rela) {
97 perror("malloc");
98 return -1;
99 }
100 memset(rela, 0, sizeof(*rela));
101
Josh Poimboeufe81e0722020-04-01 13:23:27 -0500102 if (insn_sec->sym) {
103 rela->sym = insn_sec->sym;
104 rela->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 rela->sym = find_symbol_containing(insn_sec, insn_off);
111 if (!rela->sym) {
112 /*
113 * Hack alert. This happens when we need to reference
114 * the NOP pad insn immediately after the function.
115 */
116 rela->sym = find_symbol_containing(insn_sec,
117 insn_off - 1);
118 }
119 if (!rela->sym) {
120 WARN("missing symbol for insn at offset 0x%lx\n",
121 insn_off);
122 return -1;
123 }
124
125 rela->addend = insn_off - rela->sym->offset;
126 }
127
Josh Poimboeuf627fce12017-07-11 10:33:42 -0500128 rela->type = R_X86_64_PC32;
129 rela->offset = idx * sizeof(int);
Peter Zijlstra8b5fa6b2020-03-12 11:23:36 +0100130 rela->sec = ip_relasec;
Josh Poimboeuf627fce12017-07-11 10:33:42 -0500131
Peter Zijlstra34f7c962020-03-12 14:29:38 +0100132 elf_add_rela(elf, rela);
Josh Poimboeuf627fce12017-07-11 10:33:42 -0500133
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_relasec;
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);
Simon Serce90aaf2017-12-30 14:43:32 -0600181 if (!sec)
182 return -1;
Josh Poimboeuf627fce12017-07-11 10:33:42 -0500183
184 ip_relasec = elf_create_rela_section(file->elf, sec);
185 if (!ip_relasec)
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
Peter Zijlstra8b5fa6b2020-03-12 11:23:36 +0100203 if (create_orc_entry(file->elf, u_sec, ip_relasec, idx,
Josh Poimboeuf627fce12017-07-11 10:33:42 -0500204 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) {
Peter Zijlstra8b5fa6b2020-03-12 11:23:36 +0100215 if (create_orc_entry(file->elf, u_sec, ip_relasec, idx,
Josh Poimboeuf627fce12017-07-11 10:33:42 -0500216 prev_insn->sec,
217 prev_insn->offset + prev_insn->len,
218 &empty))
219 return -1;
220
221 idx++;
222 }
223 }
224
Peter Zijlstra2b10be22020-04-17 23:15:00 +0200225 if (elf_rebuild_rela_section(file->elf, ip_relasec))
Josh Poimboeuf627fce12017-07-11 10:33:42 -0500226 return -1;
227
228 return 0;
229}