1 /*-
2 * Copyright (c) 2005-2008, Sam Leffler <sam@errno.com>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/10.3/sys/kern/subr_firmware.c 237546 2012-06-25 05:41:16Z kevlo $");
29
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/malloc.h>
33 #include <sys/queue.h>
34 #include <sys/taskqueue.h>
35 #include <sys/systm.h>
36 #include <sys/lock.h>
37 #include <sys/mutex.h>
38 #include <sys/errno.h>
39 #include <sys/linker.h>
40 #include <sys/firmware.h>
41 #include <sys/priv.h>
42 #include <sys/proc.h>
43 #include <sys/module.h>
44 #include <sys/eventhandler.h>
45
46 #include <sys/filedesc.h>
47 #include <sys/vnode.h>
48
49 /*
50 * Loadable firmware support. See sys/sys/firmware.h and firmware(9)
51 * form more details on the subsystem.
52 *
53 * 'struct firmware' is the user-visible part of the firmware table.
54 * Additional internal information is stored in a 'struct priv_fw'
55 * (currently a static array). A slot is in use if FW_INUSE is true:
56 */
57
58 #define FW_INUSE(p) ((p)->file != NULL || (p)->fw.name != NULL)
59
60 /*
61 * fw.name != NULL when an image is registered; file != NULL for
62 * autoloaded images whose handling has not been completed.
63 *
64 * The state of a slot evolves as follows:
65 * firmware_register --> fw.name = image_name
66 * (autoloaded image) --> file = module reference
67 * firmware_unregister --> fw.name = NULL
68 * (unloadentry complete) --> file = NULL
69 *
70 * In order for the above to work, the 'file' field must remain
71 * unchanged in firmware_unregister().
72 *
73 * Images residing in the same module are linked to each other
74 * through the 'parent' argument of firmware_register().
75 * One image (typically, one with the same name as the module to let
76 * the autoloading mechanism work) is considered the parent image for
77 * all other images in the same module. Children affect the refcount
78 * on the parent image preventing improper unloading of the image itself.
79 */
80
81 struct priv_fw {
82 int refcnt; /* reference count */
83
84 /*
85 * parent entry, see above. Set on firmware_register(),
86 * cleared on firmware_unregister().
87 */
88 struct priv_fw *parent;
89
90 int flags; /* record FIRMWARE_UNLOAD requests */
91 #define FW_UNLOAD 0x100
92
93 /*
94 * 'file' is private info managed by the autoload/unload code.
95 * Set at the end of firmware_get(), cleared only in the
96 * firmware_unload_task, so the latter can depend on its value even
97 * while the lock is not held.
98 */
99 linker_file_t file; /* module file, if autoloaded */
100
101 /*
102 * 'fw' is the externally visible image information.
103 * We do not make it the first field in priv_fw, to avoid the
104 * temptation of casting pointers to each other.
105 * Use PRIV_FW(fw) to get a pointer to the cointainer of fw.
106 * Beware, PRIV_FW does not work for a NULL pointer.
107 */
108 struct firmware fw; /* externally visible information */
109 };
110
111 /*
112 * PRIV_FW returns the pointer to the container of struct firmware *x.
113 * Cast to intptr_t to override the 'const' attribute of x
114 */
115 #define PRIV_FW(x) ((struct priv_fw *) \
116 ((intptr_t)(x) - offsetof(struct priv_fw, fw)) )
117
118 /*
119 * At the moment we use a static array as backing store for the registry.
120 * Should we move to a dynamic structure, keep in mind that we cannot
121 * reallocate the array because pointers are held externally.
122 * A list may work, though.
123 */
124 #define FIRMWARE_MAX 50
125 static struct priv_fw firmware_table[FIRMWARE_MAX];
126
127 /*
128 * Firmware module operations are handled in a separate task as they
129 * might sleep and they require directory context to do i/o.
130 */
131 static struct taskqueue *firmware_tq;
132 static struct task firmware_unload_task;
133
134 /*
135 * This mutex protects accesses to the firmware table.
136 */
137 static struct mtx firmware_mtx;
138 MTX_SYSINIT(firmware, &firmware_mtx, "firmware table", MTX_DEF);
139
140 /*
141 * Helper function to lookup a name.
142 * As a side effect, it sets the pointer to a free slot, if any.
143 * This way we can concentrate most of the registry scanning in
144 * this function, which makes it easier to replace the registry
145 * with some other data structure.
146 */
147 static struct priv_fw *
148 lookup(const char *name, struct priv_fw **empty_slot)
149 {
150 struct priv_fw *fp = NULL;
151 struct priv_fw *dummy;
152 int i;
153
154 if (empty_slot == NULL)
155 empty_slot = &dummy;
156 *empty_slot = NULL;
157 for (i = 0; i < FIRMWARE_MAX; i++) {
158 fp = &firmware_table[i];
159 if (fp->fw.name != NULL && strcasecmp(name, fp->fw.name) == 0)
160 break;
161 else if (!FW_INUSE(fp))
162 *empty_slot = fp;
163 }
164 return (i < FIRMWARE_MAX ) ? fp : NULL;
165 }
166
167 /*
168 * Register a firmware image with the specified name. The
169 * image name must not already be registered. If this is a
170 * subimage then parent refers to a previously registered
171 * image that this should be associated with.
172 */
173 const struct firmware *
174 firmware_register(const char *imagename, const void *data, size_t datasize,
175 unsigned int version, const struct firmware *parent)
176 {
177 struct priv_fw *match, *frp;
178 char *str;
179
180 str = strdup(imagename, M_TEMP);
181
182 mtx_lock(&firmware_mtx);
183 /*
184 * Do a lookup to make sure the name is unique or find a free slot.
185 */
186 match = lookup(imagename, &frp);
187 if (match != NULL) {
188 mtx_unlock(&firmware_mtx);
189 printf("%s: image %s already registered!\n",
190 __func__, imagename);
191 free(str, M_TEMP);
192 return NULL;
193 }
194 if (frp == NULL) {
195 mtx_unlock(&firmware_mtx);
196 printf("%s: cannot register image %s, firmware table full!\n",
197 __func__, imagename);
198 free(str, M_TEMP);
199 return NULL;
200 }
201 bzero(frp, sizeof(*frp)); /* start from a clean record */
202 frp->fw.name = str;
203 frp->fw.data = data;
204 frp->fw.datasize = datasize;
205 frp->fw.version = version;
206 if (parent != NULL)
207 frp->parent = PRIV_FW(parent);
208 mtx_unlock(&firmware_mtx);
209 if (bootverbose)
210 printf("firmware: '%s' version %u: %zu bytes loaded at %p\n",
211 imagename, version, datasize, data);
212 return &frp->fw;
213 }
214
215 /*
216 * Unregister/remove a firmware image. If there are outstanding
217 * references an error is returned and the image is not removed
218 * from the registry.
219 */
220 int
221 firmware_unregister(const char *imagename)
222 {
223 struct priv_fw *fp;
224 int err;
225
226 mtx_lock(&firmware_mtx);
227 fp = lookup(imagename, NULL);
228 if (fp == NULL) {
229 /*
230 * It is ok for the lookup to fail; this can happen
231 * when a module is unloaded on last reference and the
232 * module unload handler unregister's each of it's
233 * firmware images.
234 */
235 err = 0;
236 } else if (fp->refcnt != 0) { /* cannot unregister */
237 err = EBUSY;
238 } else {
239 linker_file_t x = fp->file; /* save value */
240
241 /*
242 * Clear the whole entry with bzero to make sure we
243 * do not forget anything. Then restore 'file' which is
244 * non-null for autoloaded images.
245 */
246 free((void *) (uintptr_t) fp->fw.name, M_TEMP);
247 bzero(fp, sizeof(struct priv_fw));
248 fp->file = x;
249 err = 0;
250 }
251 mtx_unlock(&firmware_mtx);
252 return err;
253 }
254
255 static void
256 loadimage(void *arg, int npending)
257 {
258 struct thread *td = curthread;
259 char *imagename = arg;
260 struct priv_fw *fp;
261 linker_file_t result;
262 int error;
263
264 /* synchronize with the thread that dispatched us */
265 mtx_lock(&firmware_mtx);
266 mtx_unlock(&firmware_mtx);
267
268 if (td->td_proc->p_fd->fd_rdir == NULL) {
269 printf("%s: root not mounted yet, no way to load image\n",
270 imagename);
271 goto done;
272 }
273 error = linker_reference_module(imagename, NULL, &result);
274 if (error != 0) {
275 printf("%s: could not load firmware image, error %d\n",
276 imagename, error);
277 goto done;
278 }
279
280 mtx_lock(&firmware_mtx);
281 fp = lookup(imagename, NULL);
282 if (fp == NULL || fp->file != NULL) {
283 mtx_unlock(&firmware_mtx);
284 if (fp == NULL)
285 printf("%s: firmware image loaded, "
286 "but did not register\n", imagename);
287 (void) linker_release_module(imagename, NULL, NULL);
288 goto done;
289 }
290 fp->file = result; /* record the module identity */
291 mtx_unlock(&firmware_mtx);
292 done:
293 wakeup_one(imagename); /* we're done */
294 }
295
296 /*
297 * Lookup and potentially load the specified firmware image.
298 * If the firmware is not found in the registry, try to load a kernel
299 * module named as the image name.
300 * If the firmware is located, a reference is returned. The caller must
301 * release this reference for the image to be eligible for removal/unload.
302 */
303 const struct firmware *
304 firmware_get(const char *imagename)
305 {
306 struct task fwload_task;
307 struct thread *td;
308 struct priv_fw *fp;
309
310 mtx_lock(&firmware_mtx);
311 fp = lookup(imagename, NULL);
312 if (fp != NULL)
313 goto found;
314 /*
315 * Image not present, try to load the module holding it.
316 */
317 td = curthread;
318 if (priv_check(td, PRIV_FIRMWARE_LOAD) != 0 ||
319 securelevel_gt(td->td_ucred, 0) != 0) {
320 mtx_unlock(&firmware_mtx);
321 printf("%s: insufficient privileges to "
322 "load firmware image %s\n", __func__, imagename);
323 return NULL;
324 }
325 /*
326 * Defer load to a thread with known context. linker_reference_module
327 * may do filesystem i/o which requires root & current dirs, etc.
328 * Also we must not hold any mtx's over this call which is problematic.
329 */
330 if (!cold) {
331 TASK_INIT(&fwload_task, 0, loadimage, __DECONST(void *,
332 imagename));
333 taskqueue_enqueue(firmware_tq, &fwload_task);
334 msleep(__DECONST(void *, imagename), &firmware_mtx, 0,
335 "fwload", 0);
336 }
337 /*
338 * After attempting to load the module, see if the image is registered.
339 */
340 fp = lookup(imagename, NULL);
341 if (fp == NULL) {
342 mtx_unlock(&firmware_mtx);
343 return NULL;
344 }
345 found: /* common exit point on success */
346 if (fp->refcnt == 0 && fp->parent != NULL)
347 fp->parent->refcnt++;
348 fp->refcnt++;
349 mtx_unlock(&firmware_mtx);
350 return &fp->fw;
351 }
352
353 /*
354 * Release a reference to a firmware image returned by firmware_get.
355 * The caller may specify, with the FIRMWARE_UNLOAD flag, its desire
356 * to release the resource, but the flag is only advisory.
357 *
358 * If this is the last reference to the firmware image, and this is an
359 * autoloaded module, wake up the firmware_unload_task to figure out
360 * what to do with the associated module.
361 */
362 void
363 firmware_put(const struct firmware *p, int flags)
364 {
365 struct priv_fw *fp = PRIV_FW(p);
366
367 mtx_lock(&firmware_mtx);
368 fp->refcnt--;
369 if (fp->refcnt == 0) {
370 if (fp->parent != NULL)
371 fp->parent->refcnt--;
372 if (flags & FIRMWARE_UNLOAD)
373 fp->flags |= FW_UNLOAD;
374 if (fp->file)
375 taskqueue_enqueue(firmware_tq, &firmware_unload_task);
376 }
377 mtx_unlock(&firmware_mtx);
378 }
379
380 /*
381 * Setup directory state for the firmware_tq thread so we can do i/o.
382 */
383 static void
384 set_rootvnode(void *arg, int npending)
385 {
386 struct thread *td = curthread;
387 struct proc *p = td->td_proc;
388
389 FILEDESC_XLOCK(p->p_fd);
390 if (p->p_fd->fd_cdir == NULL) {
391 p->p_fd->fd_cdir = rootvnode;
392 VREF(rootvnode);
393 }
394 if (p->p_fd->fd_rdir == NULL) {
395 p->p_fd->fd_rdir = rootvnode;
396 VREF(rootvnode);
397 }
398 FILEDESC_XUNLOCK(p->p_fd);
399
400 free(arg, M_TEMP);
401 }
402
403 /*
404 * Event handler called on mounting of /; bounce a task
405 * into the task queue thread to setup it's directories.
406 */
407 static void
408 firmware_mountroot(void *arg)
409 {
410 struct task *setroot_task;
411
412 setroot_task = malloc(sizeof(struct task), M_TEMP, M_NOWAIT);
413 if (setroot_task != NULL) {
414 TASK_INIT(setroot_task, 0, set_rootvnode, setroot_task);
415 taskqueue_enqueue(firmware_tq, setroot_task);
416 } else
417 printf("%s: no memory for task!\n", __func__);
418 }
419 EVENTHANDLER_DEFINE(mountroot, firmware_mountroot, NULL, 0);
420
421 /*
422 * The body of the task in charge of unloading autoloaded modules
423 * that are not needed anymore.
424 * Images can be cross-linked so we may need to make multiple passes,
425 * but the time we spend in the loop is bounded because we clear entries
426 * as we touch them.
427 */
428 static void
429 unloadentry(void *unused1, int unused2)
430 {
431 int limit = FIRMWARE_MAX;
432 int i; /* current cycle */
433
434 mtx_lock(&firmware_mtx);
435 /*
436 * Scan the table. limit is set to make sure we make another
437 * full sweep after matching an entry that requires unloading.
438 */
439 for (i = 0; i < limit; i++) {
440 struct priv_fw *fp;
441 int err;
442
443 fp = &firmware_table[i % FIRMWARE_MAX];
444 if (fp->fw.name == NULL || fp->file == NULL ||
445 fp->refcnt != 0 || (fp->flags & FW_UNLOAD) == 0)
446 continue;
447
448 /*
449 * Found an entry. Now:
450 * 1. bump up limit to make sure we make another full round;
451 * 2. clear FW_UNLOAD so we don't try this entry again.
452 * 3. release the lock while trying to unload the module.
453 * 'file' remains set so that the entry cannot be reused
454 * in the meantime (it also means that fp->file will
455 * not change while we release the lock).
456 */
457 limit = i + FIRMWARE_MAX; /* make another full round */
458 fp->flags &= ~FW_UNLOAD; /* do not try again */
459
460 mtx_unlock(&firmware_mtx);
461 err = linker_release_module(NULL, NULL, fp->file);
462 mtx_lock(&firmware_mtx);
463
464 /*
465 * We rely on the module to call firmware_unregister()
466 * on unload to actually release the entry.
467 * If err = 0 we can drop our reference as the system
468 * accepted it. Otherwise unloading failed (e.g. the
469 * module itself gave an error) so our reference is
470 * still valid.
471 */
472 if (err == 0)
473 fp->file = NULL;
474 }
475 mtx_unlock(&firmware_mtx);
476 }
477
478 /*
479 * Module glue.
480 */
481 static int
482 firmware_modevent(module_t mod, int type, void *unused)
483 {
484 struct priv_fw *fp;
485 int i, err;
486
487 switch (type) {
488 case MOD_LOAD:
489 TASK_INIT(&firmware_unload_task, 0, unloadentry, NULL);
490 firmware_tq = taskqueue_create("taskqueue_firmware", M_WAITOK,
491 taskqueue_thread_enqueue, &firmware_tq);
492 /* NB: use our own loop routine that sets up context */
493 (void) taskqueue_start_threads(&firmware_tq, 1, PWAIT,
494 "firmware taskq");
495 if (rootvnode != NULL) {
496 /*
497 * Root is already mounted so we won't get an event;
498 * simulate one here.
499 */
500 firmware_mountroot(NULL);
501 }
502 return 0;
503
504 case MOD_UNLOAD:
505 /* request all autoloaded modules to be released */
506 mtx_lock(&firmware_mtx);
507 for (i = 0; i < FIRMWARE_MAX; i++) {
508 fp = &firmware_table[i];
509 fp->flags |= FW_UNLOAD;
510 }
511 mtx_unlock(&firmware_mtx);
512 taskqueue_enqueue(firmware_tq, &firmware_unload_task);
513 taskqueue_drain(firmware_tq, &firmware_unload_task);
514 err = 0;
515 for (i = 0; i < FIRMWARE_MAX; i++) {
516 fp = &firmware_table[i];
517 if (fp->fw.name != NULL) {
518 printf("%s: image %p ref %d still active slot %d\n",
519 __func__, fp->fw.name,
520 fp->refcnt, i);
521 err = EINVAL;
522 }
523 }
524 if (err == 0)
525 taskqueue_free(firmware_tq);
526 return err;
527 }
528 return EINVAL;
529 }
530
531 static moduledata_t firmware_mod = {
532 "firmware",
533 firmware_modevent,
534 NULL
535 };
536 DECLARE_MODULE(firmware, firmware_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
537 MODULE_VERSION(firmware, 1);
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