1/*
  2 * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
  3 *
  4 * This program is free software; you can redistribute it and/or
  5 * modify it under the terms of the GNU General Public License
  6 * as published by the Free Software Foundation; either version 2
  7 * of the License, or (at your option) any later version.
  8 *
  9 * This program is distributed in the hope that it will be useful,
 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12 * GNU General Public License for more details.
 13 *
 14 * You should have received a copy of the GNU General Public License
 15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 16 */
 17
 18#include <stdlib.h>
 19#include <string.h>
 20
 21#include "orc.h"
 22#include "check.h"
 23#include "warn.h"
 24
 25int create_orc(struct objtool_file *file)
 26{
 27	struct instruction *insn;
 28
 29	for_each_insn(file, insn) {
 30		struct orc_entry *orc = &insn->orc;
 31		struct cfi_reg *cfa = &insn->state.cfa;
 32		struct cfi_reg *bp = &insn->state.regs[CFI_BP];
 33
 34		if (cfa->base == CFI_UNDEFINED) {
 35			orc->sp_reg = ORC_REG_UNDEFINED;
 36			continue;
 37		}
 38
 39		switch (cfa->base) {
 40		case CFI_SP:
 41			orc->sp_reg = ORC_REG_SP;
 42			break;
 43		case CFI_SP_INDIRECT:
 44			orc->sp_reg = ORC_REG_SP_INDIRECT;
 45			break;
 46		case CFI_BP:
 47			orc->sp_reg = ORC_REG_BP;
 48			break;
 49		case CFI_BP_INDIRECT:
 50			orc->sp_reg = ORC_REG_BP_INDIRECT;
 51			break;
 52		case CFI_R10:
 53			orc->sp_reg = ORC_REG_R10;
 54			break;
 55		case CFI_R13:
 56			orc->sp_reg = ORC_REG_R13;
 57			break;
 58		case CFI_DI:
 59			orc->sp_reg = ORC_REG_DI;
 60			break;
 61		case CFI_DX:
 62			orc->sp_reg = ORC_REG_DX;
 63			break;
 64		default:
 65			WARN_FUNC("unknown CFA base reg %d",
 66				  insn->sec, insn->offset, cfa->base);
 67			return -1;
 68		}
 69
 70		switch(bp->base) {
 71		case CFI_UNDEFINED:
 72			orc->bp_reg = ORC_REG_UNDEFINED;
 73			break;
 74		case CFI_CFA:
 75			orc->bp_reg = ORC_REG_PREV_SP;
 76			break;
 77		case CFI_BP:
 78			orc->bp_reg = ORC_REG_BP;
 79			break;
 80		default:
 81			WARN_FUNC("unknown BP base reg %d",
 82				  insn->sec, insn->offset, bp->base);
 83			return -1;
 84		}
 85
 86		orc->sp_offset = cfa->offset;
 87		orc->bp_offset = bp->offset;
 88		orc->type = insn->state.type;
 89	}
 90
 91	return 0;
 92}
 93
 94static int create_orc_entry(struct section *u_sec, struct section *ip_relasec,
 95				unsigned int idx, struct section *insn_sec,
 96				unsigned long insn_off, struct orc_entry *o)
 97{
 98	struct orc_entry *orc;
 99	struct rela *rela;
100
101	if (!insn_sec->sym) {
102		WARN("missing symbol for section %s", insn_sec->name);
103		return -1;
104	}
105
106	/* populate ORC data */
107	orc = (struct orc_entry *)u_sec->data->d_buf + idx;
108	memcpy(orc, o, sizeof(*orc));
109
110	/* populate rela for ip */
111	rela = malloc(sizeof(*rela));
112	if (!rela) {
113		perror("malloc");
114		return -1;
115	}
116	memset(rela, 0, sizeof(*rela));
117
118	rela->sym = insn_sec->sym;
119	rela->addend = insn_off;
120	rela->type = R_X86_64_PC32;
121	rela->offset = idx * sizeof(int);
122
123	list_add_tail(&rela->list, &ip_relasec->rela_list);
124	hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset);
125
126	return 0;
127}
128
129int create_orc_sections(struct objtool_file *file)
130{
131	struct instruction *insn, *prev_insn;
132	struct section *sec, *u_sec, *ip_relasec;
133	unsigned int idx;
134
135	struct orc_entry empty = {
136		.sp_reg = ORC_REG_UNDEFINED,
137		.bp_reg  = ORC_REG_UNDEFINED,
138		.type    = ORC_TYPE_CALL,
139	};
140
141	sec = find_section_by_name(file->elf, ".orc_unwind");
142	if (sec) {
143		WARN("file already has .orc_unwind section, skipping");
144		return -1;
145	}
146
147	/* count the number of needed orcs */
148	idx = 0;
149	for_each_sec(file, sec) {
150		if (!sec->text)
151			continue;
152
153		prev_insn = NULL;
154		sec_for_each_insn(file, sec, insn) {
155			if (!prev_insn ||
156			    memcmp(&insn->orc, &prev_insn->orc,
157				   sizeof(struct orc_entry))) {
158				idx++;
159			}
160			prev_insn = insn;
161		}
162
163		/* section terminator */
164		if (prev_insn)
165			idx++;
166	}
167	if (!idx)
168		return -1;
169
170
171	/* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
172	sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
173	if (!sec)
174		return -1;
175
176	ip_relasec = elf_create_rela_section(file->elf, sec);
177	if (!ip_relasec)
178		return -1;
179
180	/* create .orc_unwind section */
181	u_sec = elf_create_section(file->elf, ".orc_unwind",
182				   sizeof(struct orc_entry), idx);
183
184	/* populate sections */
185	idx = 0;
186	for_each_sec(file, sec) {
187		if (!sec->text)
188			continue;
189
190		prev_insn = NULL;
191		sec_for_each_insn(file, sec, insn) {
192			if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
193						 sizeof(struct orc_entry))) {
194
195				if (create_orc_entry(u_sec, ip_relasec, idx,
196						     insn->sec, insn->offset,
197						     &insn->orc))
198					return -1;
199
200				idx++;
201			}
202			prev_insn = insn;
203		}
204
205		/* section terminator */
206		if (prev_insn) {
207			if (create_orc_entry(u_sec, ip_relasec, idx,
208					     prev_insn->sec,
209					     prev_insn->offset + prev_insn->len,
210					     &empty))
211				return -1;
212
213			idx++;
214		}
215	}
216
217	if (elf_rebuild_rela_section(ip_relasec))
218		return -1;
219
220	return 0;
221}