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/orc.h>
14 #include <objtool/warn.h>
15 #include <objtool/endianness.h>
16
17 struct orc_list_entry {
18 struct list_head list;
19 struct orc_entry orc;
20 struct section *insn_sec;
21 unsigned long insn_off;
22 };
23
24 static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
25 struct section *sec, unsigned long offset)
26 {
27 struct orc_list_entry *entry = malloc(sizeof(*entry));
28
29 if (!entry) {
30 WARN("malloc failed");
31 return -1;
32 }
33
34 entry->orc = *orc;
35 entry->insn_sec = sec;
36 entry->insn_off = offset;
37
38 list_add_tail(&entry->list, orc_list);
39 return 0;
40 }
41
42 static unsigned long alt_group_len(struct alt_group *alt_group)
43 {
44 return alt_group->last_insn->offset +
45 alt_group->last_insn->len -
46 alt_group->first_insn->offset;
47 }
48
49 int orc_create(struct objtool_file *file)
50 {
51 struct section *sec, *orc_sec;
52 unsigned int nr = 0, idx = 0;
53 struct orc_list_entry *entry;
54 struct list_head orc_list;
55
56 struct orc_entry null = { .type = ORC_TYPE_UNDEFINED };
57
58 /* Build a deduplicated list of ORC entries: */
59 INIT_LIST_HEAD(&orc_list);
60 for_each_sec(file, sec) {
61 struct orc_entry orc, prev_orc = {0};
62 struct instruction *insn;
63 bool empty = true;
64
65 if (!sec->text)
66 continue;
67
68 sec_for_each_insn(file, sec, insn) {
69 struct alt_group *alt_group = insn->alt_group;
70 int i;
71
72 if (!alt_group) {
73 if (init_orc_entry(&orc, insn->cfi, insn))
74 return -1;
75 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
76 continue;
77 if (orc_list_add(&orc_list, &orc, sec,
78 insn->offset))
79 return -1;
80 nr++;
81 prev_orc = orc;
82 empty = false;
83 continue;
84 }
85
86 /*
87 * Alternatives can have different stack layout
88 * possibilities (but they shouldn't conflict).
89 * Instead of traversing the instructions, use the
90 * alt_group's flattened byte-offset-addressed CFI
91 * array.
92 */
93 for (i = 0; i < alt_group_len(alt_group); i++) {
94 struct cfi_state *cfi = alt_group->cfi[i];
95 if (!cfi)
96 continue;
97 /* errors are reported on the original insn */
98 if (init_orc_entry(&orc, cfi, insn))
99 return -1;
100 if (!memcmp(&prev_orc, &orc, sizeof(orc)))
101 continue;
102 if (orc_list_add(&orc_list, &orc, insn->sec,
103 insn->offset + i))
104 return -1;
105 nr++;
106 prev_orc = orc;
107 empty = false;
108 }
109
110 /* Skip to the end of the alt_group */
111 insn = alt_group->last_insn;
112 }
113
114 /* Add a section terminator */
115 if (!empty) {
116 orc_list_add(&orc_list, &null, sec, sec->sh.sh_size);
117 nr++;
118 }
119 }
120 if (!nr)
121 return 0;
122
123 /* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
124 sec = find_section_by_name(file->elf, ".orc_unwind");
125 if (sec) {
126 WARN("file already has .orc_unwind section, skipping");
127 return -1;
128 }
129 orc_sec = elf_create_section(file->elf, ".orc_unwind",
130 sizeof(struct orc_entry), nr);
131 if (!orc_sec)
132 return -1;
133
134 sec = elf_create_section_pair(file->elf, ".orc_unwind_ip", sizeof(int), nr, nr);
135 if (!sec)
136 return -1;
137
138 /* Write ORC entries to sections: */
139 list_for_each_entry(entry, &orc_list, list) {
140 if (write_orc_entry(file->elf, orc_sec, sec, idx++,
141 entry->insn_sec, entry->insn_off,
142 &entry->orc))
143 return -1;
144 }
145
146 return 0;
147 }
148
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