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 "orc.h"
 10#include "check.h"
 11#include "warn.h"
 12
 13int create_orc(struct objtool_file *file)
 14{
 15	struct instruction *insn;
 16
 17	for_each_insn(file, insn) {
 18		struct orc_entry *orc = &insn->orc;
 19		struct cfi_reg *cfa = &insn->state.cfa;
 20		struct cfi_reg *bp = &insn->state.regs[CFI_BP];
 21
 22		orc->end = insn->state.end;
 23
 24		if (cfa->base == CFI_UNDEFINED) {
 25			orc->sp_reg = ORC_REG_UNDEFINED;
 26			continue;
 27		}
 28
 29		switch (cfa->base) {
 30		case CFI_SP:
 31			orc->sp_reg = ORC_REG_SP;
 32			break;
 33		case CFI_SP_INDIRECT:
 34			orc->sp_reg = ORC_REG_SP_INDIRECT;
 35			break;
 36		case CFI_BP:
 37			orc->sp_reg = ORC_REG_BP;
 38			break;
 39		case CFI_BP_INDIRECT:
 40			orc->sp_reg = ORC_REG_BP_INDIRECT;
 41			break;
 42		case CFI_R10:
 43			orc->sp_reg = ORC_REG_R10;
 44			break;
 45		case CFI_R13:
 46			orc->sp_reg = ORC_REG_R13;
 47			break;
 48		case CFI_DI:
 49			orc->sp_reg = ORC_REG_DI;
 50			break;
 51		case CFI_DX:
 52			orc->sp_reg = ORC_REG_DX;
 53			break;
 54		default:
 55			WARN_FUNC("unknown CFA base reg %d",
 56				  insn->sec, insn->offset, cfa->base);
 57			return -1;
 58		}
 59
 60		switch(bp->base) {
 61		case CFI_UNDEFINED:
 62			orc->bp_reg = ORC_REG_UNDEFINED;
 63			break;
 64		case CFI_CFA:
 65			orc->bp_reg = ORC_REG_PREV_SP;
 66			break;
 67		case CFI_BP:
 68			orc->bp_reg = ORC_REG_BP;
 69			break;
 70		default:
 71			WARN_FUNC("unknown BP base reg %d",
 72				  insn->sec, insn->offset, bp->base);
 73			return -1;
 74		}
 75
 76		orc->sp_offset = cfa->offset;
 77		orc->bp_offset = bp->offset;
 78		orc->type = insn->state.type;
 79	}
 80
 81	return 0;
 82}
 83
 84static int create_orc_entry(struct section *u_sec, struct section *ip_relasec,
 85				unsigned int idx, struct section *insn_sec,
 86				unsigned long insn_off, struct orc_entry *o)
 87{
 88	struct orc_entry *orc;
 89	struct rela *rela;
 90
 91	if (!insn_sec->sym) {
 92		WARN("missing symbol for section %s", insn_sec->name);
 93		return -1;
 94	}
 95
 96	/* populate ORC data */
 97	orc = (struct orc_entry *)u_sec->data->d_buf + idx;
 98	memcpy(orc, o, sizeof(*orc));
 99
100	/* populate rela for ip */
101	rela = malloc(sizeof(*rela));
102	if (!rela) {
103		perror("malloc");
104		return -1;
105	}
106	memset(rela, 0, sizeof(*rela));
107
108	rela->sym = insn_sec->sym;
109	rela->addend = insn_off;
110	rela->type = R_X86_64_PC32;
111	rela->offset = idx * sizeof(int);
112
113	list_add_tail(&rela->list, &ip_relasec->rela_list);
114	hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset);
115
116	return 0;
117}
118
119int create_orc_sections(struct objtool_file *file)
120{
121	struct instruction *insn, *prev_insn;
122	struct section *sec, *u_sec, *ip_relasec;
123	unsigned int idx;
124
125	struct orc_entry empty = {
126		.sp_reg = ORC_REG_UNDEFINED,
127		.bp_reg  = ORC_REG_UNDEFINED,
128		.type    = ORC_TYPE_CALL,
129	};
130
131	sec = find_section_by_name(file->elf, ".orc_unwind");
132	if (sec) {
133		WARN("file already has .orc_unwind section, skipping");
134		return -1;
135	}
136
137	/* count the number of needed orcs */
138	idx = 0;
139	for_each_sec(file, sec) {
140		if (!sec->text)
141			continue;
142
143		prev_insn = NULL;
144		sec_for_each_insn(file, sec, insn) {
145			if (!prev_insn ||
146			    memcmp(&insn->orc, &prev_insn->orc,
147				   sizeof(struct orc_entry))) {
148				idx++;
149			}
150			prev_insn = insn;
151		}
152
153		/* section terminator */
154		if (prev_insn)
155			idx++;
156	}
157	if (!idx)
158		return -1;
159
160
161	/* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
162	sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
163	if (!sec)
164		return -1;
165
166	ip_relasec = elf_create_rela_section(file->elf, sec);
167	if (!ip_relasec)
168		return -1;
169
170	/* create .orc_unwind section */
171	u_sec = elf_create_section(file->elf, ".orc_unwind",
172				   sizeof(struct orc_entry), idx);
173
174	/* populate sections */
175	idx = 0;
176	for_each_sec(file, sec) {
177		if (!sec->text)
178			continue;
179
180		prev_insn = NULL;
181		sec_for_each_insn(file, sec, insn) {
182			if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
183						 sizeof(struct orc_entry))) {
184
185				if (create_orc_entry(u_sec, ip_relasec, idx,
186						     insn->sec, insn->offset,
187						     &insn->orc))
188					return -1;
189
190				idx++;
191			}
192			prev_insn = insn;
193		}
194
195		/* section terminator */
196		if (prev_insn) {
197			if (create_orc_entry(u_sec, ip_relasec, idx,
198					     prev_insn->sec,
199					     prev_insn->offset + prev_insn->len,
200					     &empty))
201				return -1;
202
203			idx++;
204		}
205	}
206
207	if (elf_rebuild_rela_section(ip_relasec))
208		return -1;
209
210	return 0;
211}