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
16struct orc_list_entry {
17 struct list_head list;
18 struct orc_entry orc;
19 struct section *insn_sec;
20 unsigned long insn_off;
21};
22
23static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
24 struct section *sec, unsigned long offset)
25{
26 struct orc_list_entry *entry = malloc(size: sizeof(*entry));
27
28 if (!entry) {
29 WARN("malloc failed");
30 return -1;
31 }
32
33 entry->orc = *orc;
34 entry->insn_sec = sec;
35 entry->insn_off = offset;
36
37 list_add_tail(new: &entry->list, head: orc_list);
38 return 0;
39}
40
41static unsigned long alt_group_len(struct alt_group *alt_group)
42{
43 return alt_group->last_insn->offset +
44 alt_group->last_insn->len -
45 alt_group->first_insn->offset;
46}
47
48int orc_create(struct objtool_file *file)
49{
50 struct section *sec, *orc_sec;
51 unsigned int nr = 0, idx = 0;
52 struct orc_list_entry *entry;
53 struct list_head orc_list;
54
55 struct orc_entry null = { .type = ORC_TYPE_UNDEFINED };
56
57 /* Build a deduplicated list of ORC entries: */
58 INIT_LIST_HEAD(list: &orc_list);
59 for_each_sec(file->elf, sec) {
60 struct orc_entry orc, prev_orc = {0};
61 struct instruction *insn;
62 bool empty = true;
63
64 if (!sec->text)
65 continue;
66
67 sec_for_each_insn(file, sec, insn) {
68 struct alt_group *alt_group = insn->alt_group;
69 int i;
70
71 if (!alt_group) {
72 if (init_orc_entry(orc: &orc, cfi: insn->cfi, insn))
73 return -1;
74 if (!memcmp(s1: &prev_orc, s2: &orc, n: sizeof(orc)))
75 continue;
76 if (orc_list_add(orc_list: &orc_list, orc: &orc, sec,
77 offset: insn->offset))
78 return -1;
79 nr++;
80 prev_orc = orc;
81 empty = false;
82 continue;
83 }
84
85 /*
86 * Alternatives can have different stack layout
87 * possibilities (but they shouldn't conflict).
88 * Instead of traversing the instructions, use the
89 * alt_group's flattened byte-offset-addressed CFI
90 * array.
91 */
92 for (i = 0; i < alt_group_len(alt_group); i++) {
93 struct cfi_state *cfi = alt_group->cfi[i];
94 if (!cfi)
95 continue;
96 /* errors are reported on the original insn */
97 if (init_orc_entry(orc: &orc, cfi, insn))
98 return -1;
99 if (!memcmp(s1: &prev_orc, s2: &orc, n: sizeof(orc)))
100 continue;
101 if (orc_list_add(orc_list: &orc_list, orc: &orc, sec: insn->sec,
102 offset: insn->offset + i))
103 return -1;
104 nr++;
105 prev_orc = orc;
106 empty = false;
107 }
108
109 /* Skip to the end of the alt_group */
110 insn = alt_group->last_insn;
111 }
112
113 /* Add a section terminator */
114 if (!empty) {
115 orc_list_add(orc_list: &orc_list, orc: &null, sec, offset: sec->sh.sh_size);
116 nr++;
117 }
118 }
119 if (!nr)
120 return 0;
121
122 /* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
123 sec = find_section_by_name(elf: file->elf, name: ".orc_unwind");
124 if (sec) {
125 WARN("file already has .orc_unwind section, skipping");
126 return -1;
127 }
128 orc_sec = elf_create_section(elf: file->elf, name: ".orc_unwind",
129 size: nr * sizeof(struct orc_entry),
130 entsize: sizeof(struct orc_entry),
131 SHT_PROGBITS,
132 align: 1,
133 SHF_ALLOC);
134 if (!orc_sec)
135 return -1;
136
137 sec = elf_create_section_pair(elf: file->elf, name: ".orc_unwind_ip", entsize: sizeof(int), nr, reloc_nr: nr);
138 if (!sec)
139 return -1;
140
141 /* Write ORC entries to sections: */
142 list_for_each_entry(entry, &orc_list, list) {
143 if (write_orc_entry(elf: file->elf, orc_sec, ip_sec: sec, idx: idx++,
144 insn_sec: entry->insn_sec, insn_off: entry->insn_off,
145 o: &entry->orc))
146 return -1;
147 }
148
149 return 0;
150}
151

source code of linux/tools/objtool/orc_gen.c