xref: /openbmc/linux/tools/perf/util/vdso.c (revision ee84a303)
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_rb_node *rb_node;
148 
149 	maps__for_each_entry(thread__maps(thread), rb_node) {
150 		struct dso *dso = map__dso(rb_node->map);
151 
152 		if (!dso || dso->long_name[0] != '/')
153 			continue;
154 		dso_type = dso__type(dso, machine);
155 		if (dso_type != DSO__TYPE_UNKNOWN)
156 			break;
157 	}
158 
159 	return dso_type;
160 }
161 
162 #if BITS_PER_LONG == 64
163 
vdso__do_copy_compat(FILE * f,int fd)164 static int vdso__do_copy_compat(FILE *f, int fd)
165 {
166 	char buf[4096];
167 	size_t count;
168 
169 	while (1) {
170 		count = fread(buf, 1, sizeof(buf), f);
171 		if (ferror(f))
172 			return -errno;
173 		if (feof(f))
174 			break;
175 		if (count && writen(fd, buf, count) != (ssize_t)count)
176 			return -errno;
177 	}
178 
179 	return 0;
180 }
181 
vdso__copy_compat(const char * prog,int fd)182 static int vdso__copy_compat(const char *prog, int fd)
183 {
184 	FILE *f;
185 	int err;
186 
187 	f = popen(prog, "r");
188 	if (!f)
189 		return -errno;
190 
191 	err = vdso__do_copy_compat(f, fd);
192 
193 	if (pclose(f) == -1)
194 		return -errno;
195 
196 	return err;
197 }
198 
vdso__create_compat_file(const char * prog,char * temp_name)199 static int vdso__create_compat_file(const char *prog, char *temp_name)
200 {
201 	int fd, err;
202 
203 	fd = mkstemp(temp_name);
204 	if (fd < 0)
205 		return -errno;
206 
207 	err = vdso__copy_compat(prog, fd);
208 
209 	if (close(fd) == -1)
210 		return -errno;
211 
212 	return err;
213 }
214 
vdso__get_compat_file(struct vdso_file * vdso_file)215 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
216 {
217 	int err;
218 
219 	if (vdso_file->found)
220 		return vdso_file->temp_file_name;
221 
222 	if (vdso_file->error)
223 		return NULL;
224 
225 	err = vdso__create_compat_file(vdso_file->read_prog,
226 				       vdso_file->temp_file_name);
227 	if (err) {
228 		pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
229 		vdso_file->error = true;
230 		return NULL;
231 	}
232 
233 	vdso_file->found = true;
234 
235 	return vdso_file->temp_file_name;
236 }
237 
__machine__findnew_compat(struct machine * machine,struct vdso_file * vdso_file)238 static struct dso *__machine__findnew_compat(struct machine *machine,
239 					     struct vdso_file *vdso_file)
240 {
241 	const char *file_name;
242 	struct dso *dso;
243 
244 	dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
245 	if (dso)
246 		goto out;
247 
248 	file_name = vdso__get_compat_file(vdso_file);
249 	if (!file_name)
250 		goto out;
251 
252 	dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
253 out:
254 	return dso;
255 }
256 
__machine__findnew_vdso_compat(struct machine * machine,struct thread * thread,struct vdso_info * vdso_info,struct dso ** dso)257 static int __machine__findnew_vdso_compat(struct machine *machine,
258 					  struct thread *thread,
259 					  struct vdso_info *vdso_info,
260 					  struct dso **dso)
261 {
262 	enum dso_type dso_type;
263 
264 	dso_type = machine__thread_dso_type(machine, thread);
265 
266 #ifndef HAVE_PERF_READ_VDSO32
267 	if (dso_type == DSO__TYPE_32BIT)
268 		return 0;
269 #endif
270 #ifndef HAVE_PERF_READ_VDSOX32
271 	if (dso_type == DSO__TYPE_X32BIT)
272 		return 0;
273 #endif
274 
275 	switch (dso_type) {
276 	case DSO__TYPE_32BIT:
277 		*dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
278 		return 1;
279 	case DSO__TYPE_X32BIT:
280 		*dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
281 		return 1;
282 	case DSO__TYPE_UNKNOWN:
283 	case DSO__TYPE_64BIT:
284 	default:
285 		return 0;
286 	}
287 }
288 
289 #endif
290 
machine__find_vdso(struct machine * machine,struct thread * thread)291 static struct dso *machine__find_vdso(struct machine *machine,
292 				      struct thread *thread)
293 {
294 	struct dso *dso = NULL;
295 	enum dso_type dso_type;
296 
297 	dso_type = machine__thread_dso_type(machine, thread);
298 	switch (dso_type) {
299 	case DSO__TYPE_32BIT:
300 		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
301 		if (!dso) {
302 			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
303 					   true);
304 			if (dso && dso_type != dso__type(dso, machine))
305 				dso = NULL;
306 		}
307 		break;
308 	case DSO__TYPE_X32BIT:
309 		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
310 		break;
311 	case DSO__TYPE_64BIT:
312 	case DSO__TYPE_UNKNOWN:
313 	default:
314 		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
315 		break;
316 	}
317 
318 	return dso;
319 }
320 
machine__findnew_vdso(struct machine * machine,struct thread * thread)321 struct dso *machine__findnew_vdso(struct machine *machine,
322 				  struct thread *thread)
323 {
324 	struct vdso_info *vdso_info;
325 	struct dso *dso = NULL;
326 
327 	down_write(&machine->dsos.lock);
328 	if (!machine->vdso_info)
329 		machine->vdso_info = vdso_info__new();
330 
331 	vdso_info = machine->vdso_info;
332 	if (!vdso_info)
333 		goto out_unlock;
334 
335 	dso = machine__find_vdso(machine, thread);
336 	if (dso)
337 		goto out_unlock;
338 
339 #if BITS_PER_LONG == 64
340 	if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
341 		goto out_unlock;
342 #endif
343 
344 	dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
345 	if (!dso) {
346 		char *file;
347 
348 		file = get_file(&vdso_info->vdso);
349 		if (file)
350 			dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
351 	}
352 
353 out_unlock:
354 	dso__get(dso);
355 	up_write(&machine->dsos.lock);
356 	return dso;
357 }
358 
dso__is_vdso(struct dso * dso)359 bool dso__is_vdso(struct dso *dso)
360 {
361 	return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
362 	       !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
363 	       !strcmp(dso->short_name, DSO__NAME_VDSOX32);
364 }
365