1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
  4 */
  5
  6/*
  7 * objtool:
  8 *
  9 * The 'check' subcmd analyzes every .o file and ensures the validity of its
 10 * stack trace metadata.  It enforces a set of rules on asm code and C inline
 11 * assembly code so that stack traces can be reliable.
 12 *
 13 * For more information, see tools/objtool/Documentation/stack-validation.txt.
 14 */
 15
 16#include <stdio.h>
 17#include <stdbool.h>
 18#include <string.h>
 19#include <stdlib.h>
 20#include <unistd.h>
 21#include <subcmd/exec-cmd.h>
 22#include <subcmd/pager.h>
 23#include <linux/kernel.h>
 24
 25#include <objtool/builtin.h>
 26#include <objtool/objtool.h>
 27#include <objtool/warn.h>
 28
 29struct cmd_struct {
 30	const char *name;
 31	int (*fn)(int, const char **);
 32	const char *help;
 33};
 34
 35static const char objtool_usage_string[] =
 36	"objtool COMMAND [ARGS]";
 37
 38static struct cmd_struct objtool_cmds[] = {
 39	{"check",	cmd_check,	"Perform stack metadata validation on an object file" },
 40	{"orc",		cmd_orc,	"Generate in-place ORC unwind tables for an object file" },
 41};
 42
 43bool help;
 44
 45const char *objname;
 46static struct objtool_file file;
 47
 48static bool objtool_create_backup(const char *_objname)
 49{
 50	int len = strlen(_objname);
 51	char *buf, *base, *name = malloc(len+6);
 52	int s, d, l, t;
 53
 54	if (!name) {
 55		perror("failed backup name malloc");
 56		return false;
 57	}
 58
 59	strcpy(name, _objname);
 60	strcpy(name + len, ".orig");
 61
 62	d = open(name, O_CREAT|O_WRONLY|O_TRUNC, 0644);
 63	if (d < 0) {
 64		perror("failed to create backup file");
 65		return false;
 66	}
 67
 68	s = open(_objname, O_RDONLY);
 69	if (s < 0) {
 70		perror("failed to open orig file");
 71		return false;
 72	}
 73
 74	buf = malloc(4096);
 75	if (!buf) {
 76		perror("failed backup data malloc");
 77		return false;
 78	}
 79
 80	while ((l = read(s, buf, 4096)) > 0) {
 81		base = buf;
 82		do {
 83			t = write(d, base, l);
 84			if (t < 0) {
 85				perror("failed backup write");
 86				return false;
 87			}
 88			base += t;
 89			l -= t;
 90		} while (l);
 91	}
 92
 93	if (l < 0) {
 94		perror("failed backup read");
 95		return false;
 96	}
 97
 98	free(name);
 99	free(buf);
100	close(d);
101	close(s);
102
103	return true;
104}
105
106struct objtool_file *objtool_open_read(const char *_objname)
107{
108	if (objname) {
109		if (strcmp(objname, _objname)) {
110			WARN("won't handle more than one file at a time");
111			return NULL;
112		}
113		return &file;
114	}
115	objname = _objname;
116
117	file.elf = elf_open_read(objname, O_RDWR);
118	if (!file.elf)
119		return NULL;
120
121	if (backup && !objtool_create_backup(objname)) {
122		WARN("can't create backup file");
123		return NULL;
124	}
125
126	INIT_LIST_HEAD(&file.insn_list);
127	hash_init(file.insn_hash);
128	INIT_LIST_HEAD(&file.retpoline_call_list);
129	INIT_LIST_HEAD(&file.static_call_list);
130	INIT_LIST_HEAD(&file.mcount_loc_list);
131	file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
132	file.ignore_unreachables = no_unreachable;
133	file.hints = false;
134
135	return &file;
136}
137
138static void cmd_usage(void)
139{
140	unsigned int i, longest = 0;
141
142	printf("\n usage: %s\n\n", objtool_usage_string);
143
144	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
145		if (longest < strlen(objtool_cmds[i].name))
146			longest = strlen(objtool_cmds[i].name);
147	}
148
149	puts(" Commands:");
150	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
151		printf("   %-*s   ", longest, objtool_cmds[i].name);
152		puts(objtool_cmds[i].help);
153	}
154
155	printf("\n");
156
157	if (!help)
158		exit(129);
159	exit(0);
160}
161
162static void handle_options(int *argc, const char ***argv)
163{
164	while (*argc > 0) {
165		const char *cmd = (*argv)[0];
166
167		if (cmd[0] != '-')
168			break;
169
170		if (!strcmp(cmd, "--help") || !strcmp(cmd, "-h")) {
171			help = true;
172			break;
173		} else {
174			fprintf(stderr, "Unknown option: %s\n", cmd);
175			cmd_usage();
176		}
177
178		(*argv)++;
179		(*argc)--;
180	}
181}
182
183static void handle_internal_command(int argc, const char **argv)
184{
185	const char *cmd = argv[0];
186	unsigned int i, ret;
187
188	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
189		struct cmd_struct *p = objtool_cmds+i;
190
191		if (strcmp(p->name, cmd))
192			continue;
193
194		ret = p->fn(argc, argv);
195
196		exit(ret);
197	}
198
199	cmd_usage();
200}
201
202int main(int argc, const char **argv)
203{
204	static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED";
205
206	/* libsubcmd init */
207	exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);
208	pager_init(UNUSED);
209
210	argv++;
211	argc--;
212	handle_options(&argc, &argv);
213
214	if (!argc || help)
215		cmd_usage();
216
217	handle_internal_command(argc, argv);
218
219	return 0;
220}