1 // SPDX-License-Identifier: GPL-2.0
2 #include <errno.h>
3 #include <unistd.h>
4 #include <stdio.h>
5 #include <string.h>
6 #include <sys/types.h>
7 #include <sys/stat.h>
8 #include <fcntl.h>
9 #include <stdlib.h>
10 #include <linux/kernel.h>
11 
12 #include "vdso.h"
13 #include "dso.h"
14 #include <internal/lib.h>
15 #include "map.h"
16 #include "symbol.h"
17 #include "machine.h"
18 #include "thread.h"
19 #include "linux/string.h"
20 #include <linux/zalloc.h>
21 #include "debug.h"
22 
23 /*
24  * Include definition of find_map() also used in perf-read-vdso.c for
25  * building perf-read-vdso32 and perf-read-vdsox32.
26  */
27 #include "find-map.c"
28 
29 #define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX"
30 
31 struct vdso_file {
32 	bool found;
33 	bool error;
34 	char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)];
35 	const char *dso_name;
36 	const char *read_prog;
37 };
38 
39 struct vdso_info {
40 	struct vdso_file vdso;
41 #if BITS_PER_LONG == 64
42 	struct vdso_file vdso32;
43 	struct vdso_file vdsox32;
44 #endif
45 };
46 
vdso_info__new(void)47 static struct vdso_info *vdso_info__new(void)
48 {
49 	static const struct vdso_info vdso_info_init = {
50 		.vdso    = {
51 			.temp_file_name = VDSO__TEMP_FILE_NAME,
52 			.dso_name = DSO__NAME_VDSO,
53 		},
54 #if BITS_PER_LONG == 64
55 		.vdso32  = {
56 			.temp_file_name = VDSO__TEMP_FILE_NAME,
57 			.dso_name = DSO__NAME_VDSO32,
58 			.read_prog = "perf-read-vdso32",
59 		},
60 		.vdsox32  = {
61 			.temp_file_name = VDSO__TEMP_FILE_NAME,
62 			.dso_name = DSO__NAME_VDSOX32,
63 			.read_prog = "perf-read-vdsox32",
64 		},
65 #endif
66 	};
67 
68 	return memdup(&vdso_info_init, sizeof(vdso_info_init));
69 }
70 
get_file(struct vdso_file * vdso_file)71 static char *get_file(struct vdso_file *vdso_file)
72 {
73 	char *vdso = NULL;
74 	char *buf = NULL;
75 	void *start, *end;
76 	size_t size;
77 	int fd;
78 
79 	if (vdso_file->found)
80 		return vdso_file->temp_file_name;
81 
82 	if (vdso_file->error || find_map(&start, &end, VDSO__MAP_NAME))
83 		return NULL;
84 
85 	size = end - start;
86 
87 	buf = memdup(start, size);
88 	if (!buf)
89 		return NULL;
90 
91 	fd = mkstemp(vdso_file->temp_file_name);
92 	if (fd < 0)
93 		goto out;
94 
95 	if (size == (size_t) write(fd, buf, size))
96 		vdso = vdso_file->temp_file_name;
97 
98 	close(fd);
99 
100  out:
101 	free(buf);
102 
103 	vdso_file->found = (vdso != NULL);
104 	vdso_file->error = !vdso_file->found;
105 	return vdso;
106 }
107 
machine__exit_vdso(struct machine * machine)108 void machine__exit_vdso(struct machine *machine)
109 {
110 	struct vdso_info *vdso_info = machine->vdso_info;
111 
112 	if (!vdso_info)
113 		return;
114 
115 	if (vdso_info->vdso.found)
116 		unlink(vdso_info->vdso.temp_file_name);
117 #if BITS_PER_LONG == 64
118 	if (vdso_info->vdso32.found)
119 		unlink(vdso_info->vdso32.temp_file_name);
120 	if (vdso_info->vdsox32.found)
121 		unlink(vdso_info->vdsox32.temp_file_name);
122 #endif
123 
124 	zfree(&machine->vdso_info);
125 }
126 
__machine__addnew_vdso(struct machine * machine,const char * short_name,const char * long_name)127 static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
128 					  const char *long_name)
129 {
130 	struct dso *dso;
131 
132 	dso = dso__new(short_name);
133 	if (dso != NULL) {
134 		__dsos__add(&machine->dsos, dso);
135 		dso__set_long_name(dso, long_name, false);
136 		/* Put dso here because __dsos_add already got it */
137 		dso__put(dso);
138 	}
139 
140 	return dso;
141 }
142 
machine__thread_dso_type(struct machine * machine,struct thread * thread)143 static enum dso_type machine__thread_dso_type(struct machine *machine,
144 					      struct thread *thread)
145 {
146 	enum dso_type dso_type = DSO__TYPE_UNKNOWN;
147 	struct map *map;
148 
149 	maps__for_each_entry(thread->maps, map) {
150 		struct dso *dso = map->dso;
151 		if (!dso || dso->long_name[0] != '/')
152 			continue;
153 		dso_type = dso__type(dso, machine);
154 		if (dso_type != DSO__TYPE_UNKNOWN)
155 			break;
156 	}
157 
158 	return dso_type;
159 }
160 
161 #if BITS_PER_LONG == 64
162 
vdso__do_copy_compat(FILE * f,int fd)163 static int vdso__do_copy_compat(FILE *f, int fd)
164 {
165 	char buf[4096];
166 	size_t count;
167 
168 	while (1) {
169 		count = fread(buf, 1, sizeof(buf), f);
170 		if (ferror(f))
171 			return -errno;
172 		if (feof(f))
173 			break;
174 		if (count && writen(fd, buf, count) != (ssize_t)count)
175 			return -errno;
176 	}
177 
178 	return 0;
179 }
180 
vdso__copy_compat(const char * prog,int fd)181 static int vdso__copy_compat(const char *prog, int fd)
182 {
183 	FILE *f;
184 	int err;
185 
186 	f = popen(prog, "r");
187 	if (!f)
188 		return -errno;
189 
190 	err = vdso__do_copy_compat(f, fd);
191 
192 	if (pclose(f) == -1)
193 		return -errno;
194 
195 	return err;
196 }
197 
vdso__create_compat_file(const char * prog,char * temp_name)198 static int vdso__create_compat_file(const char *prog, char *temp_name)
199 {
200 	int fd, err;
201 
202 	fd = mkstemp(temp_name);
203 	if (fd < 0)
204 		return -errno;
205 
206 	err = vdso__copy_compat(prog, fd);
207 
208 	if (close(fd) == -1)
209 		return -errno;
210 
211 	return err;
212 }
213 
vdso__get_compat_file(struct vdso_file * vdso_file)214 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
215 {
216 	int err;
217 
218 	if (vdso_file->found)
219 		return vdso_file->temp_file_name;
220 
221 	if (vdso_file->error)
222 		return NULL;
223 
224 	err = vdso__create_compat_file(vdso_file->read_prog,
225 				       vdso_file->temp_file_name);
226 	if (err) {
227 		pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
228 		vdso_file->error = true;
229 		return NULL;
230 	}
231 
232 	vdso_file->found = true;
233 
234 	return vdso_file->temp_file_name;
235 }
236 
__machine__findnew_compat(struct machine * machine,struct vdso_file * vdso_file)237 static struct dso *__machine__findnew_compat(struct machine *machine,
238 					     struct vdso_file *vdso_file)
239 {
240 	const char *file_name;
241 	struct dso *dso;
242 
243 	dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
244 	if (dso)
245 		goto out;
246 
247 	file_name = vdso__get_compat_file(vdso_file);
248 	if (!file_name)
249 		goto out;
250 
251 	dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
252 out:
253 	return dso;
254 }
255 
__machine__findnew_vdso_compat(struct machine * machine,struct thread * thread,struct vdso_info * vdso_info,struct dso ** dso)256 static int __machine__findnew_vdso_compat(struct machine *machine,
257 					  struct thread *thread,
258 					  struct vdso_info *vdso_info,
259 					  struct dso **dso)
260 {
261 	enum dso_type dso_type;
262 
263 	dso_type = machine__thread_dso_type(machine, thread);
264 
265 #ifndef HAVE_PERF_READ_VDSO32
266 	if (dso_type == DSO__TYPE_32BIT)
267 		return 0;
268 #endif
269 #ifndef HAVE_PERF_READ_VDSOX32
270 	if (dso_type == DSO__TYPE_X32BIT)
271 		return 0;
272 #endif
273 
274 	switch (dso_type) {
275 	case DSO__TYPE_32BIT:
276 		*dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
277 		return 1;
278 	case DSO__TYPE_X32BIT:
279 		*dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
280 		return 1;
281 	case DSO__TYPE_UNKNOWN:
282 	case DSO__TYPE_64BIT:
283 	default:
284 		return 0;
285 	}
286 }
287 
288 #endif
289 
machine__find_vdso(struct machine * machine,struct thread * thread)290 static struct dso *machine__find_vdso(struct machine *machine,
291 				      struct thread *thread)
292 {
293 	struct dso *dso = NULL;
294 	enum dso_type dso_type;
295 
296 	dso_type = machine__thread_dso_type(machine, thread);
297 	switch (dso_type) {
298 	case DSO__TYPE_32BIT:
299 		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
300 		if (!dso) {
301 			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
302 					   true);
303 			if (dso && dso_type != dso__type(dso, machine))
304 				dso = NULL;
305 		}
306 		break;
307 	case DSO__TYPE_X32BIT:
308 		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
309 		break;
310 	case DSO__TYPE_64BIT:
311 	case DSO__TYPE_UNKNOWN:
312 	default:
313 		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
314 		break;
315 	}
316 
317 	return dso;
318 }
319 
machine__findnew_vdso(struct machine * machine,struct thread * thread)320 struct dso *machine__findnew_vdso(struct machine *machine,
321 				  struct thread *thread)
322 {
323 	struct vdso_info *vdso_info;
324 	struct dso *dso = NULL;
325 
326 	down_write(&machine->dsos.lock);
327 	if (!machine->vdso_info)
328 		machine->vdso_info = vdso_info__new();
329 
330 	vdso_info = machine->vdso_info;
331 	if (!vdso_info)
332 		goto out_unlock;
333 
334 	dso = machine__find_vdso(machine, thread);
335 	if (dso)
336 		goto out_unlock;
337 
338 #if BITS_PER_LONG == 64
339 	if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
340 		goto out_unlock;
341 #endif
342 
343 	dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
344 	if (!dso) {
345 		char *file;
346 
347 		file = get_file(&vdso_info->vdso);
348 		if (file)
349 			dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
350 	}
351 
352 out_unlock:
353 	dso__get(dso);
354 	up_write(&machine->dsos.lock);
355 	return dso;
356 }
357 
dso__is_vdso(struct dso * dso)358 bool dso__is_vdso(struct dso *dso)
359 {
360 	return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
361 	       !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
362 	       !strcmp(dso->short_name, DSO__NAME_VDSOX32);
363 }
364