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}