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
17struct 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
24static 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
42static 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
49int 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