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
29 struct cmd_struct {
30 const char *name;
31 int (*fn)(int, const char **);
32 const char *help;
33 };
34
35 static const char objtool_usage_string[] =
36 "objtool COMMAND [ARGS]";
37
38 static 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
43 bool help;
44
45 const char *objname;
46 static struct objtool_file file;
47
objtool_create_backup(const char * _objname)48 static 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
objtool_open_read(const char * _objname)106 struct 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
objtool_pv_add(struct objtool_file * f,int idx,struct symbol * func)138 void objtool_pv_add(struct objtool_file *f, int idx, struct symbol *func)
139 {
140 if (!noinstr)
141 return;
142
143 if (!f->pv_ops) {
144 WARN("paravirt confusion");
145 return;
146 }
147
148 /*
149 * These functions will be patched into native code,
150 * see paravirt_patch().
151 */
152 if (!strcmp(func->name, "_paravirt_nop") ||
153 !strcmp(func->name, "_paravirt_ident_64"))
154 return;
155
156 /* already added this function */
157 if (!list_empty(&func->pv_target))
158 return;
159
160 list_add(&func->pv_target, &f->pv_ops[idx].targets);
161 f->pv_ops[idx].clean = false;
162 }
163
cmd_usage(void)164 static void cmd_usage(void)
165 {
166 unsigned int i, longest = 0;
167
168 printf("\n usage: %s\n\n", objtool_usage_string);
169
170 for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
171 if (longest < strlen(objtool_cmds[i].name))
172 longest = strlen(objtool_cmds[i].name);
173 }
174
175 puts(" Commands:");
176 for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
177 printf(" %-*s ", longest, objtool_cmds[i].name);
178 puts(objtool_cmds[i].help);
179 }
180
181 printf("\n");
182
183 if (!help)
184 exit(129);
185 exit(0);
186 }
187
handle_options(int * argc,const char *** argv)188 static void handle_options(int *argc, const char ***argv)
189 {
190 while (*argc > 0) {
191 const char *cmd = (*argv)[0];
192
193 if (cmd[0] != '-')
194 break;
195
196 if (!strcmp(cmd, "--help") || !strcmp(cmd, "-h")) {
197 help = true;
198 break;
199 } else {
200 fprintf(stderr, "Unknown option: %s\n", cmd);
201 cmd_usage();
202 }
203
204 (*argv)++;
205 (*argc)--;
206 }
207 }
208
handle_internal_command(int argc,const char ** argv)209 static void handle_internal_command(int argc, const char **argv)
210 {
211 const char *cmd = argv[0];
212 unsigned int i, ret;
213
214 for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
215 struct cmd_struct *p = objtool_cmds+i;
216
217 if (strcmp(p->name, cmd))
218 continue;
219
220 ret = p->fn(argc, argv);
221
222 exit(ret);
223 }
224
225 cmd_usage();
226 }
227
main(int argc,const char ** argv)228 int main(int argc, const char **argv)
229 {
230 static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED";
231
232 /* libsubcmd init */
233 exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);
234 pager_init(UNUSED);
235
236 argv++;
237 argc--;
238 handle_options(&argc, &argv);
239
240 if (!argc || help)
241 cmd_usage();
242
243 handle_internal_command(argc, argv);
244
245 return 0;
246 }
247