xref: /openbmc/linux/kernel/params.c (revision fcb8918f)
1 /* Helpers for initial module or kernel cmdline parsing
2    Copyright (C) 2001 Rusty Russell.
3 
4     This program is free software; you can redistribute it and/or modify
5     it under the terms of the GNU General Public License as published by
6     the Free Software Foundation; either version 2 of the License, or
7     (at your option) any later version.
8 
9     This program is distributed in the hope that it will be useful,
10     but WITHOUT ANY WARRANTY; without even the implied warranty of
11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12     GNU General Public License for more details.
13 
14     You should have received a copy of the GNU General Public License
15     along with this program; if not, write to the Free Software
16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17 */
18 #include <linux/moduleparam.h>
19 #include <linux/kernel.h>
20 #include <linux/string.h>
21 #include <linux/errno.h>
22 #include <linux/module.h>
23 #include <linux/device.h>
24 #include <linux/err.h>
25 #include <linux/slab.h>
26 #include <linux/ctype.h>
27 
28 #if 0
29 #define DEBUGP printk
30 #else
31 #define DEBUGP(fmt, a...)
32 #endif
33 
34 /* Protects all parameters, and incidentally kmalloced_param list. */
35 static DEFINE_MUTEX(param_lock);
36 
37 /* This just allows us to keep track of which parameters are kmalloced. */
38 struct kmalloced_param {
39 	struct list_head list;
40 	char val[];
41 };
42 static LIST_HEAD(kmalloced_params);
43 
44 static void *kmalloc_parameter(unsigned int size)
45 {
46 	struct kmalloced_param *p;
47 
48 	p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
49 	if (!p)
50 		return NULL;
51 
52 	list_add(&p->list, &kmalloced_params);
53 	return p->val;
54 }
55 
56 /* Does nothing if parameter wasn't kmalloced above. */
57 static void maybe_kfree_parameter(void *param)
58 {
59 	struct kmalloced_param *p;
60 
61 	list_for_each_entry(p, &kmalloced_params, list) {
62 		if (p->val == param) {
63 			list_del(&p->list);
64 			kfree(p);
65 			break;
66 		}
67 	}
68 }
69 
70 static inline char dash2underscore(char c)
71 {
72 	if (c == '-')
73 		return '_';
74 	return c;
75 }
76 
77 static inline int parameq(const char *input, const char *paramname)
78 {
79 	unsigned int i;
80 	for (i = 0; dash2underscore(input[i]) == paramname[i]; i++)
81 		if (input[i] == '\0')
82 			return 1;
83 	return 0;
84 }
85 
86 static int parse_one(char *param,
87 		     char *val,
88 		     const struct kernel_param *params,
89 		     unsigned num_params,
90 		     int (*handle_unknown)(char *param, char *val))
91 {
92 	unsigned int i;
93 	int err;
94 
95 	/* Find parameter */
96 	for (i = 0; i < num_params; i++) {
97 		if (parameq(param, params[i].name)) {
98 			/* Noone handled NULL, so do it here. */
99 			if (!val && params[i].ops->set != param_set_bool)
100 				return -EINVAL;
101 			DEBUGP("They are equal!  Calling %p\n",
102 			       params[i].ops->set);
103 			mutex_lock(&param_lock);
104 			err = params[i].ops->set(val, &params[i]);
105 			mutex_unlock(&param_lock);
106 			return err;
107 		}
108 	}
109 
110 	if (handle_unknown) {
111 		DEBUGP("Unknown argument: calling %p\n", handle_unknown);
112 		return handle_unknown(param, val);
113 	}
114 
115 	DEBUGP("Unknown argument `%s'\n", param);
116 	return -ENOENT;
117 }
118 
119 /* You can use " around spaces, but can't escape ". */
120 /* Hyphens and underscores equivalent in parameter names. */
121 static char *next_arg(char *args, char **param, char **val)
122 {
123 	unsigned int i, equals = 0;
124 	int in_quote = 0, quoted = 0;
125 	char *next;
126 
127 	if (*args == '"') {
128 		args++;
129 		in_quote = 1;
130 		quoted = 1;
131 	}
132 
133 	for (i = 0; args[i]; i++) {
134 		if (isspace(args[i]) && !in_quote)
135 			break;
136 		if (equals == 0) {
137 			if (args[i] == '=')
138 				equals = i;
139 		}
140 		if (args[i] == '"')
141 			in_quote = !in_quote;
142 	}
143 
144 	*param = args;
145 	if (!equals)
146 		*val = NULL;
147 	else {
148 		args[equals] = '\0';
149 		*val = args + equals + 1;
150 
151 		/* Don't include quotes in value. */
152 		if (**val == '"') {
153 			(*val)++;
154 			if (args[i-1] == '"')
155 				args[i-1] = '\0';
156 		}
157 		if (quoted && args[i-1] == '"')
158 			args[i-1] = '\0';
159 	}
160 
161 	if (args[i]) {
162 		args[i] = '\0';
163 		next = args + i + 1;
164 	} else
165 		next = args + i;
166 
167 	/* Chew up trailing spaces. */
168 	return skip_spaces(next);
169 }
170 
171 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
172 int parse_args(const char *name,
173 	       char *args,
174 	       const struct kernel_param *params,
175 	       unsigned num,
176 	       int (*unknown)(char *param, char *val))
177 {
178 	char *param, *val;
179 
180 	DEBUGP("Parsing ARGS: %s\n", args);
181 
182 	/* Chew leading spaces */
183 	args = skip_spaces(args);
184 
185 	while (*args) {
186 		int ret;
187 		int irq_was_disabled;
188 
189 		args = next_arg(args, &param, &val);
190 		irq_was_disabled = irqs_disabled();
191 		ret = parse_one(param, val, params, num, unknown);
192 		if (irq_was_disabled && !irqs_disabled()) {
193 			printk(KERN_WARNING "parse_args(): option '%s' enabled "
194 					"irq's!\n", param);
195 		}
196 		switch (ret) {
197 		case -ENOENT:
198 			printk(KERN_ERR "%s: Unknown parameter `%s'\n",
199 			       name, param);
200 			return ret;
201 		case -ENOSPC:
202 			printk(KERN_ERR
203 			       "%s: `%s' too large for parameter `%s'\n",
204 			       name, val ?: "", param);
205 			return ret;
206 		case 0:
207 			break;
208 		default:
209 			printk(KERN_ERR
210 			       "%s: `%s' invalid for parameter `%s'\n",
211 			       name, val ?: "", param);
212 			return ret;
213 		}
214 	}
215 
216 	/* All parsed OK. */
217 	return 0;
218 }
219 
220 /* Lazy bastard, eh? */
221 #define STANDARD_PARAM_DEF(name, type, format, tmptype, strtolfn)      	\
222 	int param_set_##name(const char *val, const struct kernel_param *kp) \
223 	{								\
224 		tmptype l;						\
225 		int ret;						\
226 									\
227 		ret = strtolfn(val, 0, &l);				\
228 		if (ret == -EINVAL || ((type)l != l))			\
229 			return -EINVAL;					\
230 		*((type *)kp->arg) = l;					\
231 		return 0;						\
232 	}								\
233 	int param_get_##name(char *buffer, const struct kernel_param *kp) \
234 	{								\
235 		return sprintf(buffer, format, *((type *)kp->arg));	\
236 	}								\
237 	struct kernel_param_ops param_ops_##name = {			\
238 		.set = param_set_##name,				\
239 		.get = param_get_##name,				\
240 	};								\
241 	EXPORT_SYMBOL(param_set_##name);				\
242 	EXPORT_SYMBOL(param_get_##name);				\
243 	EXPORT_SYMBOL(param_ops_##name)
244 
245 
246 STANDARD_PARAM_DEF(byte, unsigned char, "%c", unsigned long, strict_strtoul);
247 STANDARD_PARAM_DEF(short, short, "%hi", long, strict_strtol);
248 STANDARD_PARAM_DEF(ushort, unsigned short, "%hu", unsigned long, strict_strtoul);
249 STANDARD_PARAM_DEF(int, int, "%i", long, strict_strtol);
250 STANDARD_PARAM_DEF(uint, unsigned int, "%u", unsigned long, strict_strtoul);
251 STANDARD_PARAM_DEF(long, long, "%li", long, strict_strtol);
252 STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, strict_strtoul);
253 
254 int param_set_charp(const char *val, const struct kernel_param *kp)
255 {
256 	if (strlen(val) > 1024) {
257 		printk(KERN_ERR "%s: string parameter too long\n",
258 		       kp->name);
259 		return -ENOSPC;
260 	}
261 
262 	maybe_kfree_parameter(*(char **)kp->arg);
263 
264 	/* This is a hack.  We can't kmalloc in early boot, and we
265 	 * don't need to; this mangled commandline is preserved. */
266 	if (slab_is_available()) {
267 		*(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
268 		if (!*(char **)kp->arg)
269 			return -ENOMEM;
270 		strcpy(*(char **)kp->arg, val);
271 	} else
272 		*(const char **)kp->arg = val;
273 
274 	return 0;
275 }
276 EXPORT_SYMBOL(param_set_charp);
277 
278 int param_get_charp(char *buffer, const struct kernel_param *kp)
279 {
280 	return sprintf(buffer, "%s", *((char **)kp->arg));
281 }
282 EXPORT_SYMBOL(param_get_charp);
283 
284 static void param_free_charp(void *arg)
285 {
286 	maybe_kfree_parameter(*((char **)arg));
287 }
288 
289 struct kernel_param_ops param_ops_charp = {
290 	.set = param_set_charp,
291 	.get = param_get_charp,
292 	.free = param_free_charp,
293 };
294 EXPORT_SYMBOL(param_ops_charp);
295 
296 /* Actually could be a bool or an int, for historical reasons. */
297 int param_set_bool(const char *val, const struct kernel_param *kp)
298 {
299 	bool v;
300 
301 	/* No equals means "set"... */
302 	if (!val) val = "1";
303 
304 	/* One of =[yYnN01] */
305 	switch (val[0]) {
306 	case 'y': case 'Y': case '1':
307 		v = true;
308 		break;
309 	case 'n': case 'N': case '0':
310 		v = false;
311 		break;
312 	default:
313 		return -EINVAL;
314 	}
315 
316 	if (kp->flags & KPARAM_ISBOOL)
317 		*(bool *)kp->arg = v;
318 	else
319 		*(int *)kp->arg = v;
320 	return 0;
321 }
322 EXPORT_SYMBOL(param_set_bool);
323 
324 int param_get_bool(char *buffer, const struct kernel_param *kp)
325 {
326 	bool val;
327 	if (kp->flags & KPARAM_ISBOOL)
328 		val = *(bool *)kp->arg;
329 	else
330 		val = *(int *)kp->arg;
331 
332 	/* Y and N chosen as being relatively non-coder friendly */
333 	return sprintf(buffer, "%c", val ? 'Y' : 'N');
334 }
335 EXPORT_SYMBOL(param_get_bool);
336 
337 struct kernel_param_ops param_ops_bool = {
338 	.set = param_set_bool,
339 	.get = param_get_bool,
340 };
341 EXPORT_SYMBOL(param_ops_bool);
342 
343 /* This one must be bool. */
344 int param_set_invbool(const char *val, const struct kernel_param *kp)
345 {
346 	int ret;
347 	bool boolval;
348 	struct kernel_param dummy;
349 
350 	dummy.arg = &boolval;
351 	dummy.flags = KPARAM_ISBOOL;
352 	ret = param_set_bool(val, &dummy);
353 	if (ret == 0)
354 		*(bool *)kp->arg = !boolval;
355 	return ret;
356 }
357 EXPORT_SYMBOL(param_set_invbool);
358 
359 int param_get_invbool(char *buffer, const struct kernel_param *kp)
360 {
361 	return sprintf(buffer, "%c", (*(bool *)kp->arg) ? 'N' : 'Y');
362 }
363 EXPORT_SYMBOL(param_get_invbool);
364 
365 struct kernel_param_ops param_ops_invbool = {
366 	.set = param_set_invbool,
367 	.get = param_get_invbool,
368 };
369 EXPORT_SYMBOL(param_ops_invbool);
370 
371 /* We break the rule and mangle the string. */
372 static int param_array(const char *name,
373 		       const char *val,
374 		       unsigned int min, unsigned int max,
375 		       void *elem, int elemsize,
376 		       int (*set)(const char *, const struct kernel_param *kp),
377 		       u16 flags,
378 		       unsigned int *num)
379 {
380 	int ret;
381 	struct kernel_param kp;
382 	char save;
383 
384 	/* Get the name right for errors. */
385 	kp.name = name;
386 	kp.arg = elem;
387 	kp.flags = flags;
388 
389 	*num = 0;
390 	/* We expect a comma-separated list of values. */
391 	do {
392 		int len;
393 
394 		if (*num == max) {
395 			printk(KERN_ERR "%s: can only take %i arguments\n",
396 			       name, max);
397 			return -EINVAL;
398 		}
399 		len = strcspn(val, ",");
400 
401 		/* nul-terminate and parse */
402 		save = val[len];
403 		((char *)val)[len] = '\0';
404 		BUG_ON(!mutex_is_locked(&param_lock));
405 		ret = set(val, &kp);
406 
407 		if (ret != 0)
408 			return ret;
409 		kp.arg += elemsize;
410 		val += len+1;
411 		(*num)++;
412 	} while (save == ',');
413 
414 	if (*num < min) {
415 		printk(KERN_ERR "%s: needs at least %i arguments\n",
416 		       name, min);
417 		return -EINVAL;
418 	}
419 	return 0;
420 }
421 
422 static int param_array_set(const char *val, const struct kernel_param *kp)
423 {
424 	const struct kparam_array *arr = kp->arr;
425 	unsigned int temp_num;
426 
427 	return param_array(kp->name, val, 1, arr->max, arr->elem,
428 			   arr->elemsize, arr->ops->set, kp->flags,
429 			   arr->num ?: &temp_num);
430 }
431 
432 static int param_array_get(char *buffer, const struct kernel_param *kp)
433 {
434 	int i, off, ret;
435 	const struct kparam_array *arr = kp->arr;
436 	struct kernel_param p;
437 
438 	p = *kp;
439 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
440 		if (i)
441 			buffer[off++] = ',';
442 		p.arg = arr->elem + arr->elemsize * i;
443 		BUG_ON(!mutex_is_locked(&param_lock));
444 		ret = arr->ops->get(buffer + off, &p);
445 		if (ret < 0)
446 			return ret;
447 		off += ret;
448 	}
449 	buffer[off] = '\0';
450 	return off;
451 }
452 
453 static void param_array_free(void *arg)
454 {
455 	unsigned int i;
456 	const struct kparam_array *arr = arg;
457 
458 	if (arr->ops->free)
459 		for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
460 			arr->ops->free(arr->elem + arr->elemsize * i);
461 }
462 
463 struct kernel_param_ops param_array_ops = {
464 	.set = param_array_set,
465 	.get = param_array_get,
466 	.free = param_array_free,
467 };
468 EXPORT_SYMBOL(param_array_ops);
469 
470 int param_set_copystring(const char *val, const struct kernel_param *kp)
471 {
472 	const struct kparam_string *kps = kp->str;
473 
474 	if (strlen(val)+1 > kps->maxlen) {
475 		printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
476 		       kp->name, kps->maxlen-1);
477 		return -ENOSPC;
478 	}
479 	strcpy(kps->string, val);
480 	return 0;
481 }
482 EXPORT_SYMBOL(param_set_copystring);
483 
484 int param_get_string(char *buffer, const struct kernel_param *kp)
485 {
486 	const struct kparam_string *kps = kp->str;
487 	return strlcpy(buffer, kps->string, kps->maxlen);
488 }
489 EXPORT_SYMBOL(param_get_string);
490 
491 struct kernel_param_ops param_ops_string = {
492 	.set = param_set_copystring,
493 	.get = param_get_string,
494 };
495 EXPORT_SYMBOL(param_ops_string);
496 
497 /* sysfs output in /sys/modules/XYZ/parameters/ */
498 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
499 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
500 
501 extern struct kernel_param __start___param[], __stop___param[];
502 
503 struct param_attribute
504 {
505 	struct module_attribute mattr;
506 	const struct kernel_param *param;
507 };
508 
509 struct module_param_attrs
510 {
511 	unsigned int num;
512 	struct attribute_group grp;
513 	struct param_attribute attrs[0];
514 };
515 
516 #ifdef CONFIG_SYSFS
517 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
518 
519 static ssize_t param_attr_show(struct module_attribute *mattr,
520 			       struct module *mod, char *buf)
521 {
522 	int count;
523 	struct param_attribute *attribute = to_param_attr(mattr);
524 
525 	if (!attribute->param->ops->get)
526 		return -EPERM;
527 
528 	mutex_lock(&param_lock);
529 	count = attribute->param->ops->get(buf, attribute->param);
530 	mutex_unlock(&param_lock);
531 	if (count > 0) {
532 		strcat(buf, "\n");
533 		++count;
534 	}
535 	return count;
536 }
537 
538 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
539 static ssize_t param_attr_store(struct module_attribute *mattr,
540 				struct module *owner,
541 				const char *buf, size_t len)
542 {
543  	int err;
544 	struct param_attribute *attribute = to_param_attr(mattr);
545 
546 	if (!attribute->param->ops->set)
547 		return -EPERM;
548 
549 	mutex_lock(&param_lock);
550 	err = attribute->param->ops->set(buf, attribute->param);
551 	mutex_unlock(&param_lock);
552 	if (!err)
553 		return len;
554 	return err;
555 }
556 #endif
557 
558 #ifdef CONFIG_MODULES
559 #define __modinit
560 #else
561 #define __modinit __init
562 #endif
563 
564 #ifdef CONFIG_SYSFS
565 void __kernel_param_lock(void)
566 {
567 	mutex_lock(&param_lock);
568 }
569 EXPORT_SYMBOL(__kernel_param_lock);
570 
571 void __kernel_param_unlock(void)
572 {
573 	mutex_unlock(&param_lock);
574 }
575 EXPORT_SYMBOL(__kernel_param_unlock);
576 
577 /*
578  * add_sysfs_param - add a parameter to sysfs
579  * @mk: struct module_kobject
580  * @kparam: the actual parameter definition to add to sysfs
581  * @name: name of parameter
582  *
583  * Create a kobject if for a (per-module) parameter if mp NULL, and
584  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
585  * if there's an error.
586  */
587 static __modinit int add_sysfs_param(struct module_kobject *mk,
588 				     const struct kernel_param *kp,
589 				     const char *name)
590 {
591 	struct module_param_attrs *new;
592 	struct attribute **attrs;
593 	int err, num;
594 
595 	/* We don't bother calling this with invisible parameters. */
596 	BUG_ON(!kp->perm);
597 
598 	if (!mk->mp) {
599 		num = 0;
600 		attrs = NULL;
601 	} else {
602 		num = mk->mp->num;
603 		attrs = mk->mp->grp.attrs;
604 	}
605 
606 	/* Enlarge. */
607 	new = krealloc(mk->mp,
608 		       sizeof(*mk->mp) + sizeof(mk->mp->attrs[0]) * (num+1),
609 		       GFP_KERNEL);
610 	if (!new) {
611 		kfree(mk->mp);
612 		err = -ENOMEM;
613 		goto fail;
614 	}
615 	attrs = krealloc(attrs, sizeof(new->grp.attrs[0])*(num+2), GFP_KERNEL);
616 	if (!attrs) {
617 		err = -ENOMEM;
618 		goto fail_free_new;
619 	}
620 
621 	/* Sysfs wants everything zeroed. */
622 	memset(new, 0, sizeof(*new));
623 	memset(&new->attrs[num], 0, sizeof(new->attrs[num]));
624 	memset(&attrs[num], 0, sizeof(attrs[num]));
625 	new->grp.name = "parameters";
626 	new->grp.attrs = attrs;
627 
628 	/* Tack new one on the end. */
629 	sysfs_attr_init(&new->attrs[num].mattr.attr);
630 	new->attrs[num].param = kp;
631 	new->attrs[num].mattr.show = param_attr_show;
632 	new->attrs[num].mattr.store = param_attr_store;
633 	new->attrs[num].mattr.attr.name = (char *)name;
634 	new->attrs[num].mattr.attr.mode = kp->perm;
635 	new->num = num+1;
636 
637 	/* Fix up all the pointers, since krealloc can move us */
638 	for (num = 0; num < new->num; num++)
639 		new->grp.attrs[num] = &new->attrs[num].mattr.attr;
640 	new->grp.attrs[num] = NULL;
641 
642 	mk->mp = new;
643 	return 0;
644 
645 fail_free_new:
646 	kfree(new);
647 fail:
648 	mk->mp = NULL;
649 	return err;
650 }
651 
652 #ifdef CONFIG_MODULES
653 static void free_module_param_attrs(struct module_kobject *mk)
654 {
655 	kfree(mk->mp->grp.attrs);
656 	kfree(mk->mp);
657 	mk->mp = NULL;
658 }
659 
660 /*
661  * module_param_sysfs_setup - setup sysfs support for one module
662  * @mod: module
663  * @kparam: module parameters (array)
664  * @num_params: number of module parameters
665  *
666  * Adds sysfs entries for module parameters under
667  * /sys/module/[mod->name]/parameters/
668  */
669 int module_param_sysfs_setup(struct module *mod,
670 			     const struct kernel_param *kparam,
671 			     unsigned int num_params)
672 {
673 	int i, err;
674 	bool params = false;
675 
676 	for (i = 0; i < num_params; i++) {
677 		if (kparam[i].perm == 0)
678 			continue;
679 		err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
680 		if (err)
681 			return err;
682 		params = true;
683 	}
684 
685 	if (!params)
686 		return 0;
687 
688 	/* Create the param group. */
689 	err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
690 	if (err)
691 		free_module_param_attrs(&mod->mkobj);
692 	return err;
693 }
694 
695 /*
696  * module_param_sysfs_remove - remove sysfs support for one module
697  * @mod: module
698  *
699  * Remove sysfs entries for module parameters and the corresponding
700  * kobject.
701  */
702 void module_param_sysfs_remove(struct module *mod)
703 {
704 	if (mod->mkobj.mp) {
705 		sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
706 		/* We are positive that no one is using any param
707 		 * attrs at this point.  Deallocate immediately. */
708 		free_module_param_attrs(&mod->mkobj);
709 	}
710 }
711 #endif
712 
713 void destroy_params(const struct kernel_param *params, unsigned num)
714 {
715 	unsigned int i;
716 
717 	for (i = 0; i < num; i++)
718 		if (params[i].ops->free)
719 			params[i].ops->free(params[i].arg);
720 }
721 
722 static struct module_kobject * __init locate_module_kobject(const char *name)
723 {
724 	struct module_kobject *mk;
725 	struct kobject *kobj;
726 	int err;
727 
728 	kobj = kset_find_obj(module_kset, name);
729 	if (kobj) {
730 		mk = to_module_kobject(kobj);
731 	} else {
732 		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
733 		BUG_ON(!mk);
734 
735 		mk->mod = THIS_MODULE;
736 		mk->kobj.kset = module_kset;
737 		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
738 					   "%s", name);
739 		if (err) {
740 			kobject_put(&mk->kobj);
741 			printk(KERN_ERR
742 				"Module '%s' failed add to sysfs, error number %d\n",
743 				name, err);
744 			printk(KERN_ERR
745 				"The system will be unstable now.\n");
746 			return NULL;
747 		}
748 
749 		/* So that we hold reference in both cases. */
750 		kobject_get(&mk->kobj);
751 	}
752 
753 	return mk;
754 }
755 
756 static void __init kernel_add_sysfs_param(const char *name,
757 					  struct kernel_param *kparam,
758 					  unsigned int name_skip)
759 {
760 	struct module_kobject *mk;
761 	int err;
762 
763 	mk = locate_module_kobject(name);
764 	if (!mk)
765 		return;
766 
767 	/* We need to remove old parameters before adding more. */
768 	if (mk->mp)
769 		sysfs_remove_group(&mk->kobj, &mk->mp->grp);
770 
771 	/* These should not fail at boot. */
772 	err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
773 	BUG_ON(err);
774 	err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
775 	BUG_ON(err);
776 	kobject_uevent(&mk->kobj, KOBJ_ADD);
777 	kobject_put(&mk->kobj);
778 }
779 
780 /*
781  * param_sysfs_builtin - add contents in /sys/parameters for built-in modules
782  *
783  * Add module_parameters to sysfs for "modules" built into the kernel.
784  *
785  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
786  * "parameter" name is stored behind a dot in kernel_param->name. So,
787  * extract the "module" name for all built-in kernel_param-eters,
788  * and for all who have the same, call kernel_add_sysfs_param.
789  */
790 static void __init param_sysfs_builtin(void)
791 {
792 	struct kernel_param *kp;
793 	unsigned int name_len;
794 	char modname[MODULE_NAME_LEN];
795 
796 	for (kp = __start___param; kp < __stop___param; kp++) {
797 		char *dot;
798 
799 		if (kp->perm == 0)
800 			continue;
801 
802 		dot = strchr(kp->name, '.');
803 		if (!dot) {
804 			/* This happens for core_param() */
805 			strcpy(modname, "kernel");
806 			name_len = 0;
807 		} else {
808 			name_len = dot - kp->name + 1;
809 			strlcpy(modname, kp->name, name_len);
810 		}
811 		kernel_add_sysfs_param(modname, kp, name_len);
812 	}
813 }
814 
815 ssize_t __modver_version_show(struct module_attribute *mattr,
816 			      struct module *mod, char *buf)
817 {
818 	struct module_version_attribute *vattr =
819 		container_of(mattr, struct module_version_attribute, mattr);
820 
821 	return sprintf(buf, "%s\n", vattr->version);
822 }
823 
824 extern struct module_version_attribute __start___modver[], __stop___modver[];
825 
826 static void __init version_sysfs_builtin(void)
827 {
828 	const struct module_version_attribute *vattr;
829 	struct module_kobject *mk;
830 	int err;
831 
832 	for (vattr = __start___modver; vattr < __stop___modver; vattr++) {
833 		mk = locate_module_kobject(vattr->module_name);
834 		if (mk) {
835 			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
836 			kobject_uevent(&mk->kobj, KOBJ_ADD);
837 			kobject_put(&mk->kobj);
838 		}
839 	}
840 }
841 
842 /* module-related sysfs stuff */
843 
844 static ssize_t module_attr_show(struct kobject *kobj,
845 				struct attribute *attr,
846 				char *buf)
847 {
848 	struct module_attribute *attribute;
849 	struct module_kobject *mk;
850 	int ret;
851 
852 	attribute = to_module_attr(attr);
853 	mk = to_module_kobject(kobj);
854 
855 	if (!attribute->show)
856 		return -EIO;
857 
858 	ret = attribute->show(attribute, mk->mod, buf);
859 
860 	return ret;
861 }
862 
863 static ssize_t module_attr_store(struct kobject *kobj,
864 				struct attribute *attr,
865 				const char *buf, size_t len)
866 {
867 	struct module_attribute *attribute;
868 	struct module_kobject *mk;
869 	int ret;
870 
871 	attribute = to_module_attr(attr);
872 	mk = to_module_kobject(kobj);
873 
874 	if (!attribute->store)
875 		return -EIO;
876 
877 	ret = attribute->store(attribute, mk->mod, buf, len);
878 
879 	return ret;
880 }
881 
882 static const struct sysfs_ops module_sysfs_ops = {
883 	.show = module_attr_show,
884 	.store = module_attr_store,
885 };
886 
887 static int uevent_filter(struct kset *kset, struct kobject *kobj)
888 {
889 	struct kobj_type *ktype = get_ktype(kobj);
890 
891 	if (ktype == &module_ktype)
892 		return 1;
893 	return 0;
894 }
895 
896 static const struct kset_uevent_ops module_uevent_ops = {
897 	.filter = uevent_filter,
898 };
899 
900 struct kset *module_kset;
901 int module_sysfs_initialized;
902 
903 struct kobj_type module_ktype = {
904 	.sysfs_ops =	&module_sysfs_ops,
905 };
906 
907 /*
908  * param_sysfs_init - wrapper for built-in params support
909  */
910 static int __init param_sysfs_init(void)
911 {
912 	module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
913 	if (!module_kset) {
914 		printk(KERN_WARNING "%s (%d): error creating kset\n",
915 			__FILE__, __LINE__);
916 		return -ENOMEM;
917 	}
918 	module_sysfs_initialized = 1;
919 
920 	version_sysfs_builtin();
921 	param_sysfs_builtin();
922 
923 	return 0;
924 }
925 subsys_initcall(param_sysfs_init);
926 
927 #endif /* CONFIG_SYSFS */
928