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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};
37
38static struct configfs_subsystem stp_policy_subsys;
39
40void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
41 unsigned int *mstart, unsigned int *mend,
42 unsigned int *cstart, unsigned int *cend)
43{
44 *mstart = policy_node->first_master;
45 *mend = policy_node->last_master;
46 *cstart = policy_node->first_channel;
47 *cend = policy_node->last_channel;
48}
49
50static inline char *stp_policy_node_name(struct stp_policy_node *policy_node)
51{
52 return policy_node->group.cg_item.ci_name ? : "<none>";
53}
54
55static inline struct stp_policy *to_stp_policy(struct config_item *item)
56{
57 return item ?
58 container_of(to_config_group(item), struct stp_policy, group) :
59 NULL;
60}
61
62static inline struct stp_policy_node *
63to_stp_policy_node(struct config_item *item)
64{
65 return item ?
66 container_of(to_config_group(item), struct stp_policy_node,
67 group) :
68 NULL;
69}
70
71static ssize_t
72stp_policy_node_masters_show(struct config_item *item, char *page)
73{
74 struct stp_policy_node *policy_node = to_stp_policy_node(item);
75 ssize_t count;
76
77 count = sprintf(page, "%u %u\n", policy_node->first_master,
78 policy_node->last_master);
79
80 return count;
81}
82
83static ssize_t
84stp_policy_node_masters_store(struct config_item *item, const char *page,
85 size_t count)
86{
87 struct stp_policy_node *policy_node = to_stp_policy_node(item);
88 unsigned int first, last;
89 struct stm_device *stm;
90 char *p = (char *)page;
91 ssize_t ret = -ENODEV;
92
93 if (sscanf(p, "%u %u", &first, &last) != 2)
94 return -EINVAL;
95
96 mutex_lock(&stp_policy_subsys.su_mutex);
97 stm = policy_node->policy->stm;
98 if (!stm)
99 goto unlock;
100
101 /* must be within [sw_start..sw_end], which is an inclusive range */
102 if (first > last || first < stm->data->sw_start ||
103 last > stm->data->sw_end) {
104 ret = -ERANGE;
105 goto unlock;
106 }
107
108 ret = count;
109 policy_node->first_master = first;
110 policy_node->last_master = last;
111
112unlock:
113 mutex_unlock(&stp_policy_subsys.su_mutex);
114
115 return ret;
116}
117
118static ssize_t
119stp_policy_node_channels_show(struct config_item *item, char *page)
120{
121 struct stp_policy_node *policy_node = to_stp_policy_node(item);
122 ssize_t count;
123
124 count = sprintf(page, "%u %u\n", policy_node->first_channel,
125 policy_node->last_channel);
126
127 return count;
128}
129
130static ssize_t
131stp_policy_node_channels_store(struct config_item *item, const char *page,
132 size_t count)
133{
134 struct stp_policy_node *policy_node = to_stp_policy_node(item);
135 unsigned int first, last;
136 struct stm_device *stm;
137 char *p = (char *)page;
138 ssize_t ret = -ENODEV;
139
140 if (sscanf(p, "%u %u", &first, &last) != 2)
141 return -EINVAL;
142
143 mutex_lock(&stp_policy_subsys.su_mutex);
144 stm = policy_node->policy->stm;
145 if (!stm)
146 goto unlock;
147
148 if (first > INT_MAX || last > INT_MAX || first > last ||
149 last >= stm->data->sw_nchannels) {
150 ret = -ERANGE;
151 goto unlock;
152 }
153
154 ret = count;
155 policy_node->first_channel = first;
156 policy_node->last_channel = last;
157
158unlock:
159 mutex_unlock(&stp_policy_subsys.su_mutex);
160
161 return ret;
162}
163
164static void stp_policy_node_release(struct config_item *item)
165{
166 kfree(to_stp_policy_node(item));
167}
168
169static struct configfs_item_operations stp_policy_node_item_ops = {
170 .release = stp_policy_node_release,
171};
172
173CONFIGFS_ATTR(stp_policy_node_, masters);
174CONFIGFS_ATTR(stp_policy_node_, channels);
175
176static struct configfs_attribute *stp_policy_node_attrs[] = {
177 &stp_policy_node_attr_masters,
178 &stp_policy_node_attr_channels,
179 NULL,
180};
181
182static const struct config_item_type stp_policy_type;
183static const struct config_item_type stp_policy_node_type;
184
185static struct config_group *
186stp_policy_node_make(struct config_group *group, const char *name)
187{
188 struct stp_policy_node *policy_node, *parent_node;
189 struct stp_policy *policy;
190
191 if (group->cg_item.ci_type == &stp_policy_type) {
192 policy = container_of(group, struct stp_policy, group);
193 } else {
194 parent_node = container_of(group, struct stp_policy_node,
195 group);
196 policy = parent_node->policy;
197 }
198
199 if (!policy->stm)
200 return ERR_PTR(-ENODEV);
201
202 policy_node = kzalloc(sizeof(struct stp_policy_node), GFP_KERNEL);
203 if (!policy_node)
204 return ERR_PTR(-ENOMEM);
205
206 config_group_init_type_name(&policy_node->group, name,
207 &stp_policy_node_type);
208
209 policy_node->policy = policy;
210
211 /* default values for the attributes */
212 policy_node->first_master = policy->stm->data->sw_start;
213 policy_node->last_master = policy->stm->data->sw_end;
214 policy_node->first_channel = 0;
215 policy_node->last_channel = policy->stm->data->sw_nchannels - 1;
216
217 return &policy_node->group;
218}
219
220static void
221stp_policy_node_drop(struct config_group *group, struct config_item *item)
222{
223 config_item_put(item);
224}
225
226static struct configfs_group_operations stp_policy_node_group_ops = {
227 .make_group = stp_policy_node_make,
228 .drop_item = stp_policy_node_drop,
229};
230
231static const struct config_item_type stp_policy_node_type = {
232 .ct_item_ops = &stp_policy_node_item_ops,
233 .ct_group_ops = &stp_policy_node_group_ops,
234 .ct_attrs = stp_policy_node_attrs,
235 .ct_owner = THIS_MODULE,
236};
237
238/*
239 * Root group: policies.
240 */
241static ssize_t stp_policy_device_show(struct config_item *item,
242 char *page)
243{
244 struct stp_policy *policy = to_stp_policy(item);
245 ssize_t count;
246
247 count = sprintf(page, "%s\n",
248 (policy && policy->stm) ?
249 policy->stm->data->name :
250 "<none>");
251
252 return count;
253}
254
255CONFIGFS_ATTR_RO(stp_policy_, device);
256
257static struct configfs_attribute *stp_policy_attrs[] = {
258 &stp_policy_attr_device,
259 NULL,
260};
261
262void stp_policy_unbind(struct stp_policy *policy)
263{
264 struct stm_device *stm = policy->stm;
265
266 /*
267 * stp_policy_release() will not call here if the policy is already
268 * unbound; other users should not either, as no link exists between
269 * this policy and anything else in that case
270 */
271 if (WARN_ON_ONCE(!policy->stm))
272 return;
273
274 lockdep_assert_held(&stm->policy_mutex);
275
276 stm->policy = NULL;
277 policy->stm = NULL;
278
279 stm_put_device(stm);
280}
281
282static void stp_policy_release(struct config_item *item)
283{
284 struct stp_policy *policy = to_stp_policy(item);
285 struct stm_device *stm = policy->stm;
286
287 /* a policy *can* be unbound and still exist in configfs tree */
288 if (!stm)
289 return;
290
291 mutex_lock(&stm->policy_mutex);
292 stp_policy_unbind(policy);
293 mutex_unlock(&stm->policy_mutex);
294
295 kfree(policy);
296}
297
298static struct configfs_item_operations stp_policy_item_ops = {
299 .release = stp_policy_release,
300};
301
302static struct configfs_group_operations stp_policy_group_ops = {
303 .make_group = stp_policy_node_make,
304};
305
306static const struct config_item_type stp_policy_type = {
307 .ct_item_ops = &stp_policy_item_ops,
308 .ct_group_ops = &stp_policy_group_ops,
309 .ct_attrs = stp_policy_attrs,
310 .ct_owner = THIS_MODULE,
311};
312
313static struct config_group *
314stp_policies_make(struct config_group *group, const char *name)
315{
316 struct config_group *ret;
317 struct stm_device *stm;
318 char *devname, *p;
319
320 devname = kasprintf(GFP_KERNEL, "%s", name);
321 if (!devname)
322 return ERR_PTR(-ENOMEM);
323
324 /*
325 * node must look like <device_name>.<policy_name>, where
326 * <device_name> is the name of an existing stm device; may
327 * contain dots;
328 * <policy_name> is an arbitrary string; may not contain dots
329 */
330 p = strrchr(devname, '.');
331 if (!p) {
332 kfree(devname);
333 return ERR_PTR(-EINVAL);
334 }
335
336 *p = '\0';
337
338 stm = stm_find_device(devname);
339 kfree(devname);
340
341 if (!stm)
342 return ERR_PTR(-ENODEV);
343
344 mutex_lock(&stm->policy_mutex);
345 if (stm->policy) {
346 ret = ERR_PTR(-EBUSY);
347 goto unlock_policy;
348 }
349
350 stm->policy = kzalloc(sizeof(*stm->policy), GFP_KERNEL);
351 if (!stm->policy) {
352 ret = ERR_PTR(-ENOMEM);
353 goto unlock_policy;
354 }
355
356 config_group_init_type_name(&stm->policy->group, name,
357 &stp_policy_type);
358 stm->policy->stm = stm;
359
360 ret = &stm->policy->group;
361
362unlock_policy:
363 mutex_unlock(&stm->policy_mutex);
364
365 if (IS_ERR(ret))
366 stm_put_device(stm);
367
368 return ret;
369}
370
371static struct configfs_group_operations stp_policies_group_ops = {
372 .make_group = stp_policies_make,
373};
374
375static const struct config_item_type stp_policies_type = {
376 .ct_group_ops = &stp_policies_group_ops,
377 .ct_owner = THIS_MODULE,
378};
379
380static struct configfs_subsystem stp_policy_subsys = {
381 .su_group = {
382 .cg_item = {
383 .ci_namebuf = "stp-policy",
384 .ci_type = &stp_policies_type,
385 },
386 },
387};
388
389/*
390 * Lock the policy mutex from the outside
391 */
392static struct stp_policy_node *
393__stp_policy_node_lookup(struct stp_policy *policy, char *s)
394{
395 struct stp_policy_node *policy_node, *ret;
396 struct list_head *head = &policy->group.cg_children;
397 struct config_item *item;
398 char *start, *end = s;
399
400 if (list_empty(head))
401 return NULL;
402
403 /* return the first entry if everything else fails */
404 item = list_entry(head->next, struct config_item, ci_entry);
405 ret = to_stp_policy_node(item);
406
407next:
408 for (;;) {
409 start = strsep(&end, "/");
410 if (!start)
411 break;
412
413 if (!*start)
414 continue;
415
416 list_for_each_entry(item, head, ci_entry) {
417 policy_node = to_stp_policy_node(item);
418
419 if (!strcmp(start,
420 policy_node->group.cg_item.ci_name)) {
421 ret = policy_node;
422
423 if (!end)
424 goto out;
425
426 head = &policy_node->group.cg_children;
427 goto next;
428 }
429 }
430 break;
431 }
432
433out:
434 return ret;
435}
436
437
438struct stp_policy_node *
439stp_policy_node_lookup(struct stm_device *stm, char *s)
440{
441 struct stp_policy_node *policy_node = NULL;
442
443 mutex_lock(&stp_policy_subsys.su_mutex);
444
445 mutex_lock(&stm->policy_mutex);
446 if (stm->policy)
447 policy_node = __stp_policy_node_lookup(stm->policy, s);
448 mutex_unlock(&stm->policy_mutex);
449
450 if (policy_node)
451 config_item_get(&policy_node->group.cg_item);
452 mutex_unlock(&stp_policy_subsys.su_mutex);
453
454 return policy_node;
455}
456
457void stp_policy_node_put(struct stp_policy_node *policy_node)
458{
459 config_item_put(&policy_node->group.cg_item);
460}
461
462int __init stp_configfs_init(void)
463{
464 int err;
465
466 config_group_init(&stp_policy_subsys.su_group);
467 mutex_init(&stp_policy_subsys.su_mutex);
468 err = configfs_register_subsystem(&stp_policy_subsys);
469
470 return err;
471}
472
473void __exit stp_configfs_exit(void)
474{
475 configfs_unregister_subsystem(&stp_policy_subsys);
476}