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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * System Trace Module (STM) master/channel allocation policy management
4 * Copyright (c) 2014, Intel Corporation.
5 *
6 * A master/channel allocation policy allows mapping string identifiers to
7 * master and channel ranges, where allocation can be done.
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/types.h>
13#include <linux/module.h>
14#include <linux/device.h>
15#include <linux/configfs.h>
16#include <linux/slab.h>
17#include <linux/stm.h>
18#include "stm.h"
19
20/*
21 * STP Master/Channel allocation policy configfs layout.
22 */
23
24struct stp_policy {
25 struct config_group group;
26 struct stm_device *stm;
27};
28
29struct stp_policy_node {
30 struct config_group group;
31 struct stp_policy *policy;
32 unsigned int first_master;
33 unsigned int last_master;
34 unsigned int first_channel;
35 unsigned int last_channel;
36 /* this is the one that's exposed to the attributes */
37 unsigned char priv[];
38};
39
40void *stp_policy_node_priv(struct stp_policy_node *pn)
41{
42 if (!pn)
43 return NULL;
44
45 return pn->priv;
46}
47
48static struct configfs_subsystem stp_policy_subsys;
49
50void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
51 unsigned int *mstart, unsigned int *mend,
52 unsigned int *cstart, unsigned int *cend)
53{
54 *mstart = policy_node->first_master;
55 *mend = policy_node->last_master;
56 *cstart = policy_node->first_channel;
57 *cend = policy_node->last_channel;
58}
59
60static inline char *stp_policy_node_name(struct stp_policy_node *policy_node)
61{
62 return policy_node->group.cg_item.ci_name ? : "<none>";
63}
64
65static inline struct stp_policy *to_stp_policy(struct config_item *item)
66{
67 return item ?
68 container_of(to_config_group(item), struct stp_policy, group) :
69 NULL;
70}
71
72static inline struct stp_policy_node *
73to_stp_policy_node(struct config_item *item)
74{
75 return item ?
76 container_of(to_config_group(item), struct stp_policy_node,
77 group) :
78 NULL;
79}
80
81void *to_pdrv_policy_node(struct config_item *item)
82{
83 struct stp_policy_node *node = to_stp_policy_node(item);
84
85 return stp_policy_node_priv(node);
86}
87EXPORT_SYMBOL_GPL(to_pdrv_policy_node);
88
89static ssize_t
90stp_policy_node_masters_show(struct config_item *item, char *page)
91{
92 struct stp_policy_node *policy_node = to_stp_policy_node(item);
93 ssize_t count;
94
95 count = sprintf(page, "%u %u\n", policy_node->first_master,
96 policy_node->last_master);
97
98 return count;
99}
100
101static ssize_t
102stp_policy_node_masters_store(struct config_item *item, const char *page,
103 size_t count)
104{
105 struct stp_policy_node *policy_node = to_stp_policy_node(item);
106 unsigned int first, last;
107 struct stm_device *stm;
108 char *p = (char *)page;
109 ssize_t ret = -ENODEV;
110
111 if (sscanf(p, "%u %u", &first, &last) != 2)
112 return -EINVAL;
113
114 mutex_lock(&stp_policy_subsys.su_mutex);
115 stm = policy_node->policy->stm;
116 if (!stm)
117 goto unlock;
118
119 /* must be within [sw_start..sw_end], which is an inclusive range */
120 if (first > last || first < stm->data->sw_start ||
121 last > stm->data->sw_end) {
122 ret = -ERANGE;
123 goto unlock;
124 }
125
126 ret = count;
127 policy_node->first_master = first;
128 policy_node->last_master = last;
129
130unlock:
131 mutex_unlock(&stp_policy_subsys.su_mutex);
132
133 return ret;
134}
135
136static ssize_t
137stp_policy_node_channels_show(struct config_item *item, char *page)
138{
139 struct stp_policy_node *policy_node = to_stp_policy_node(item);
140 ssize_t count;
141
142 count = sprintf(page, "%u %u\n", policy_node->first_channel,
143 policy_node->last_channel);
144
145 return count;
146}
147
148static ssize_t
149stp_policy_node_channels_store(struct config_item *item, const char *page,
150 size_t count)
151{
152 struct stp_policy_node *policy_node = to_stp_policy_node(item);
153 unsigned int first, last;
154 struct stm_device *stm;
155 char *p = (char *)page;
156 ssize_t ret = -ENODEV;
157
158 if (sscanf(p, "%u %u", &first, &last) != 2)
159 return -EINVAL;
160
161 mutex_lock(&stp_policy_subsys.su_mutex);
162 stm = policy_node->policy->stm;
163 if (!stm)
164 goto unlock;
165
166 if (first > INT_MAX || last > INT_MAX || first > last ||
167 last >= stm->data->sw_nchannels) {
168 ret = -ERANGE;
169 goto unlock;
170 }
171
172 ret = count;
173 policy_node->first_channel = first;
174 policy_node->last_channel = last;
175
176unlock:
177 mutex_unlock(&stp_policy_subsys.su_mutex);
178
179 return ret;
180}
181
182static void stp_policy_node_release(struct config_item *item)
183{
184 struct stp_policy_node *node = to_stp_policy_node(item);
185
186 kfree(node);
187}
188
189static struct configfs_item_operations stp_policy_node_item_ops = {
190 .release = stp_policy_node_release,
191};
192
193CONFIGFS_ATTR(stp_policy_node_, masters);
194CONFIGFS_ATTR(stp_policy_node_, channels);
195
196static struct configfs_attribute *stp_policy_node_attrs[] = {
197 &stp_policy_node_attr_masters,
198 &stp_policy_node_attr_channels,
199 NULL,
200};
201
202static const struct config_item_type stp_policy_type;
203static const struct config_item_type stp_policy_node_type;
204
205const struct config_item_type *
206get_policy_node_type(struct configfs_attribute **attrs)
207{
208 struct config_item_type *type;
209 struct configfs_attribute **merged;
210
211 type = kmemdup(&stp_policy_node_type, sizeof(stp_policy_node_type),
212 GFP_KERNEL);
213 if (!type)
214 return NULL;
215
216 merged = memcat_p(stp_policy_node_attrs, attrs);
217 if (!merged) {
218 kfree(type);
219 return NULL;
220 }
221
222 type->ct_attrs = merged;
223
224 return type;
225}
226
227static struct config_group *
228stp_policy_node_make(struct config_group *group, const char *name)
229{
230 const struct config_item_type *type = &stp_policy_node_type;
231 struct stp_policy_node *policy_node, *parent_node;
232 const struct stm_protocol_driver *pdrv;
233 struct stp_policy *policy;
234
235 if (group->cg_item.ci_type == &stp_policy_type) {
236 policy = container_of(group, struct stp_policy, group);
237 } else {
238 parent_node = container_of(group, struct stp_policy_node,
239 group);
240 policy = parent_node->policy;
241 }
242
243 if (!policy->stm)
244 return ERR_PTR(-ENODEV);
245
246 pdrv = policy->stm->pdrv;
247 policy_node =
248 kzalloc(offsetof(struct stp_policy_node, priv[pdrv->priv_sz]),
249 GFP_KERNEL);
250 if (!policy_node)
251 return ERR_PTR(-ENOMEM);
252
253 if (pdrv->policy_node_init)
254 pdrv->policy_node_init((void *)policy_node->priv);
255
256 if (policy->stm->pdrv_node_type)
257 type = policy->stm->pdrv_node_type;
258
259 config_group_init_type_name(&policy_node->group, name, type);
260
261 policy_node->policy = policy;
262
263 /* default values for the attributes */
264 policy_node->first_master = policy->stm->data->sw_start;
265 policy_node->last_master = policy->stm->data->sw_end;
266 policy_node->first_channel = 0;
267 policy_node->last_channel = policy->stm->data->sw_nchannels - 1;
268
269 return &policy_node->group;
270}
271
272static void
273stp_policy_node_drop(struct config_group *group, struct config_item *item)
274{
275 config_item_put(item);
276}
277
278static struct configfs_group_operations stp_policy_node_group_ops = {
279 .make_group = stp_policy_node_make,
280 .drop_item = stp_policy_node_drop,
281};
282
283static const struct config_item_type stp_policy_node_type = {
284 .ct_item_ops = &stp_policy_node_item_ops,
285 .ct_group_ops = &stp_policy_node_group_ops,
286 .ct_attrs = stp_policy_node_attrs,
287 .ct_owner = THIS_MODULE,
288};
289
290/*
291 * Root group: policies.
292 */
293static ssize_t stp_policy_device_show(struct config_item *item,
294 char *page)
295{
296 struct stp_policy *policy = to_stp_policy(item);
297 ssize_t count;
298
299 count = sprintf(page, "%s\n",
300 (policy && policy->stm) ?
301 policy->stm->data->name :
302 "<none>");
303
304 return count;
305}
306
307CONFIGFS_ATTR_RO(stp_policy_, device);
308
309static ssize_t stp_policy_protocol_show(struct config_item *item,
310 char *page)
311{
312 struct stp_policy *policy = to_stp_policy(item);
313 ssize_t count;
314
315 count = sprintf(page, "%s\n",
316 (policy && policy->stm) ?
317 policy->stm->pdrv->name :
318 "<none>");
319
320 return count;
321}
322
323CONFIGFS_ATTR_RO(stp_policy_, protocol);
324
325static struct configfs_attribute *stp_policy_attrs[] = {
326 &stp_policy_attr_device,
327 &stp_policy_attr_protocol,
328 NULL,
329};
330
331void stp_policy_unbind(struct stp_policy *policy)
332{
333 struct stm_device *stm = policy->stm;
334
335 /*
336 * stp_policy_release() will not call here if the policy is already
337 * unbound; other users should not either, as no link exists between
338 * this policy and anything else in that case
339 */
340 if (WARN_ON_ONCE(!policy->stm))
341 return;
342
343 lockdep_assert_held(&stm->policy_mutex);
344
345 stm->policy = NULL;
346 policy->stm = NULL;
347
348 /*
349 * Drop the reference on the protocol driver and lose the link.
350 */
351 stm_put_protocol(stm->pdrv);
352 stm->pdrv = NULL;
353 stm_put_device(stm);
354}
355
356static void stp_policy_release(struct config_item *item)
357{
358 struct stp_policy *policy = to_stp_policy(item);
359 struct stm_device *stm = policy->stm;
360
361 /* a policy *can* be unbound and still exist in configfs tree */
362 if (!stm)
363 return;
364
365 mutex_lock(&stm->policy_mutex);
366 stp_policy_unbind(policy);
367 mutex_unlock(&stm->policy_mutex);
368
369 kfree(policy);
370}
371
372static struct configfs_item_operations stp_policy_item_ops = {
373 .release = stp_policy_release,
374};
375
376static struct configfs_group_operations stp_policy_group_ops = {
377 .make_group = stp_policy_node_make,
378};
379
380static const struct config_item_type stp_policy_type = {
381 .ct_item_ops = &stp_policy_item_ops,
382 .ct_group_ops = &stp_policy_group_ops,
383 .ct_attrs = stp_policy_attrs,
384 .ct_owner = THIS_MODULE,
385};
386
387static struct config_group *
388stp_policy_make(struct config_group *group, const char *name)
389{
390 const struct config_item_type *pdrv_node_type;
391 const struct stm_protocol_driver *pdrv;
392 char *devname, *proto, *p;
393 struct config_group *ret;
394 struct stm_device *stm;
395 int err;
396
397 devname = kasprintf(GFP_KERNEL, "%s", name);
398 if (!devname)
399 return ERR_PTR(-ENOMEM);
400
401 /*
402 * node must look like <device_name>.<policy_name>, where
403 * <device_name> is the name of an existing stm device; may
404 * contain dots;
405 * <policy_name> is an arbitrary string; may not contain dots
406 * <device_name>:<protocol_name>.<policy_name>
407 */
408 p = strrchr(devname, '.');
409 if (!p) {
410 kfree(devname);
411 return ERR_PTR(-EINVAL);
412 }
413
414 *p = '\0';
415
416 /*
417 * look for ":<protocol_name>":
418 * + no protocol suffix: fall back to whatever is available;
419 * + unknown protocol: fail the whole thing
420 */
421 proto = strrchr(devname, ':');
422 if (proto)
423 *proto++ = '\0';
424
425 stm = stm_find_device(devname);
426 if (!stm) {
427 kfree(devname);
428 return ERR_PTR(-ENODEV);
429 }
430
431 err = stm_lookup_protocol(proto, &pdrv, &pdrv_node_type);
432 kfree(devname);
433
434 if (err) {
435 stm_put_device(stm);
436 return ERR_PTR(-ENODEV);
437 }
438
439 mutex_lock(&stm->policy_mutex);
440 if (stm->policy) {
441 ret = ERR_PTR(-EBUSY);
442 goto unlock_policy;
443 }
444
445 stm->policy = kzalloc(sizeof(*stm->policy), GFP_KERNEL);
446 if (!stm->policy) {
447 ret = ERR_PTR(-ENOMEM);
448 goto unlock_policy;
449 }
450
451 config_group_init_type_name(&stm->policy->group, name,
452 &stp_policy_type);
453
454 stm->pdrv = pdrv;
455 stm->pdrv_node_type = pdrv_node_type;
456 stm->policy->stm = stm;
457 ret = &stm->policy->group;
458
459unlock_policy:
460 mutex_unlock(&stm->policy_mutex);
461
462 if (IS_ERR(ret)) {
463 /*
464 * pdrv and stm->pdrv at this point can be quite different,
465 * and only one of them needs to be 'put'
466 */
467 stm_put_protocol(pdrv);
468 stm_put_device(stm);
469 }
470
471 return ret;
472}
473
474static struct configfs_group_operations stp_policy_root_group_ops = {
475 .make_group = stp_policy_make,
476};
477
478static const struct config_item_type stp_policy_root_type = {
479 .ct_group_ops = &stp_policy_root_group_ops,
480 .ct_owner = THIS_MODULE,
481};
482
483static struct configfs_subsystem stp_policy_subsys = {
484 .su_group = {
485 .cg_item = {
486 .ci_namebuf = "stp-policy",
487 .ci_type = &stp_policy_root_type,
488 },
489 },
490};
491
492/*
493 * Lock the policy mutex from the outside
494 */
495static struct stp_policy_node *
496__stp_policy_node_lookup(struct stp_policy *policy, char *s)
497{
498 struct stp_policy_node *policy_node, *ret = NULL;
499 struct list_head *head = &policy->group.cg_children;
500 struct config_item *item;
501 char *start, *end = s;
502
503 if (list_empty(head))
504 return NULL;
505
506next:
507 for (;;) {
508 start = strsep(&end, "/");
509 if (!start)
510 break;
511
512 if (!*start)
513 continue;
514
515 list_for_each_entry(item, head, ci_entry) {
516 policy_node = to_stp_policy_node(item);
517
518 if (!strcmp(start,
519 policy_node->group.cg_item.ci_name)) {
520 ret = policy_node;
521
522 if (!end)
523 goto out;
524
525 head = &policy_node->group.cg_children;
526 goto next;
527 }
528 }
529 break;
530 }
531
532out:
533 return ret;
534}
535
536
537struct stp_policy_node *
538stp_policy_node_lookup(struct stm_device *stm, char *s)
539{
540 struct stp_policy_node *policy_node = NULL;
541
542 mutex_lock(&stp_policy_subsys.su_mutex);
543
544 mutex_lock(&stm->policy_mutex);
545 if (stm->policy)
546 policy_node = __stp_policy_node_lookup(stm->policy, s);
547 mutex_unlock(&stm->policy_mutex);
548
549 if (policy_node)
550 config_item_get(&policy_node->group.cg_item);
551 else
552 mutex_unlock(&stp_policy_subsys.su_mutex);
553
554 return policy_node;
555}
556
557void stp_policy_node_put(struct stp_policy_node *policy_node)
558{
559 lockdep_assert_held(&stp_policy_subsys.su_mutex);
560
561 mutex_unlock(&stp_policy_subsys.su_mutex);
562 config_item_put(&policy_node->group.cg_item);
563}
564
565int __init stp_configfs_init(void)
566{
567 config_group_init(&stp_policy_subsys.su_group);
568 mutex_init(&stp_policy_subsys.su_mutex);
569 return configfs_register_subsystem(&stp_policy_subsys);
570}
571
572void __exit stp_configfs_exit(void)
573{
574 configfs_unregister_subsystem(&stp_policy_subsys);
575}