1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
*/
#include <stdlib.h>
#include <string.h>
#include <linux/objtool.h>
#include <asm/orc_types.h>
#include <objtool/check.h>
#include <objtool/warn.h>
#include <objtool/endianness.h>
static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi)
{
struct instruction *insn = container_of(cfi, struct instruction, cfi);
struct cfi_reg *bp = &cfi->regs[CFI_BP];
memset(orc, 0, sizeof(*orc));
orc->end = cfi->end;
if (cfi->cfa.base == CFI_UNDEFINED) {
orc->sp_reg = ORC_REG_UNDEFINED;
return 0;
}
switch (cfi->cfa.base) {
case CFI_SP:
orc->sp_reg = ORC_REG_SP;
break;
case CFI_SP_INDIRECT:
orc->sp_reg = ORC_REG_SP_INDIRECT;
break;
case CFI_BP:
orc->sp_reg = ORC_REG_BP;
break;
case CFI_BP_INDIRECT:
orc->sp_reg = ORC_REG_BP_INDIRECT;
break;
case CFI_R10:
orc->sp_reg = ORC_REG_R10;
break;
case CFI_R13:
orc->sp_reg = ORC_REG_R13;
break;
case CFI_DI:
orc->sp_reg = ORC_REG_DI;
break;
case CFI_DX:
orc->sp_reg = ORC_REG_DX;
break;
default:
WARN_FUNC("unknown CFA base reg %d",
insn->sec, insn->offset, cfi->cfa.base);
return -1;
}
switch (bp->base) {
case CFI_UNDEFINED:
orc->bp_reg = ORC_REG_UNDEFINED;
break;
case CFI_CFA:
orc->bp_reg = ORC_REG_PREV_SP;
break;
case CFI_BP:
orc->bp_reg = ORC_REG_BP;
break;
default:
WARN_FUNC("unknown BP base reg %d",
insn->sec, insn->offset, bp->base);
return -1;
}
orc->sp_offset = cfi->cfa.offset;
orc->bp_offset = bp->offset;
orc->type = cfi->type;
return 0;
}
static int write_orc_entry(struct elf *elf, struct section *orc_sec,
struct section *ip_rsec, unsigned int idx,
struct section *insn_sec, unsigned long insn_off,
struct orc_entry *o)
{
struct orc_entry *orc;
struct reloc *reloc;
/* populate ORC data */
orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
memcpy(orc, o, sizeof(*orc));
orc->sp_offset = bswap_if_needed(orc->sp_offset);
orc->bp_offset = bswap_if_needed(orc->bp_offset);
/* populate reloc for ip */
reloc = malloc(sizeof(*reloc));
if (!reloc) {
perror("malloc");
return -1;
}
memset(reloc, 0, sizeof(*reloc));
insn_to_reloc_sym_addend(insn_sec, insn_off, reloc);
if (!reloc->sym) {
WARN("missing symbol for insn at offset 0x%lx",
insn_off);
return -1;
}
reloc->type = R_X86_64_PC32;
reloc->offset = idx * sizeof(int);
reloc->sec = ip_rsec;
elf_add_reloc(elf, reloc);
return 0;
}
struct orc_list_entry {
struct list_head list;
struct orc_entry orc;
struct section *insn_sec;
unsigned long insn_off;
};
static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
struct section *sec, unsigned long offset)
{
struct orc_list_entry *entry = malloc(sizeof(*entry));
if (!entry) {
WARN("malloc failed");
return -1;
}
entry->orc = *orc;
entry->insn_sec = sec;
entry->insn_off = offset;
list_add_tail(&entry->list, orc_list);
return 0;
}
static unsigned long alt_group_len(struct alt_group *alt_group)
{
return alt_group->last_insn->offset +
alt_group->last_insn->len -
alt_group->first_insn->offset;
}
int orc_create(struct objtool_file *file)
{
struct section *sec, *ip_rsec, *orc_sec;
unsigned int nr = 0, idx = 0;
struct orc_list_entry *entry;
struct list_head orc_list;
struct orc_entry null = {
.sp_reg = ORC_REG_UNDEFINED,
.bp_reg = ORC_REG_UNDEFINED,
.type = UNWIND_HINT_TYPE_CALL,
};
/* Build a deduplicated list of ORC entries: */
INIT_LIST_HEAD(&orc_list);
for_each_sec(file, sec) {
struct orc_entry orc, prev_orc = {0};
struct instruction *insn;
bool empty = true;
if (!sec->text)
continue;
sec_for_each_insn(file, sec, insn) {
struct alt_group *alt_group = insn->alt_group;
int i;
if (!alt_group) {
if (init_orc_entry(&orc, &insn->cfi))
return -1;
if (!memcmp(&prev_orc, &orc, sizeof(orc)))
continue;
if (orc_list_add(&orc_list, &orc, sec,
insn->offset))
return -1;
nr++;
prev_orc = orc;
empty = false;
continue;
}
/*
* Alternatives can have different stack layout
* possibilities (but they shouldn't conflict).
* Instead of traversing the instructions, use the
* alt_group's flattened byte-offset-addressed CFI
* array.
*/
for (i = 0; i < alt_group_len(alt_group); i++) {
struct cfi_state *cfi = alt_group->cfi[i];
if (!cfi)
continue;
if (init_orc_entry(&orc, cfi))
return -1;
if (!memcmp(&prev_orc, &orc, sizeof(orc)))
continue;
if (orc_list_add(&orc_list, &orc, insn->sec,
insn->offset + i))
return -1;
nr++;
prev_orc = orc;
empty = false;
}
/* Skip to the end of the alt_group */
insn = alt_group->last_insn;
}
/* Add a section terminator */
if (!empty) {
orc_list_add(&orc_list, &null, sec, sec->len);
nr++;
}
}
if (!nr)
return 0;
/* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
sec = find_section_by_name(file->elf, ".orc_unwind");
if (sec) {
WARN("file already has .orc_unwind section, skipping");
return -1;
}
orc_sec = elf_create_section(file->elf, ".orc_unwind", 0,
sizeof(struct orc_entry), nr);
if (!orc_sec)
return -1;
sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr);
if (!sec)
return -1;
ip_rsec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
if (!ip_rsec)
return -1;
/* Write ORC entries to sections: */
list_for_each_entry(entry, &orc_list, list) {
if (write_orc_entry(file->elf, orc_sec, ip_rsec, idx++,
entry->insn_sec, entry->insn_off,
&entry->orc))
return -1;
}
if (elf_rebuild_reloc_section(file->elf, ip_rsec))
return -1;
return 0;
}
|
