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Linux/tools/perf/util/vdso.c

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

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