xref: /openbmc/linux/kernel/params.c (revision 7fe2f639)
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 			/* No one 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 	int ret;
301 
302 	/* No equals means "set"... */
303 	if (!val) val = "1";
304 
305 	/* One of =[yYnN01] */
306 	ret = strtobool(val, &v);
307 	if (ret)
308 		return ret;
309 
310 	if (kp->flags & KPARAM_ISBOOL)
311 		*(bool *)kp->arg = v;
312 	else
313 		*(int *)kp->arg = v;
314 	return 0;
315 }
316 EXPORT_SYMBOL(param_set_bool);
317 
318 int param_get_bool(char *buffer, const struct kernel_param *kp)
319 {
320 	bool val;
321 	if (kp->flags & KPARAM_ISBOOL)
322 		val = *(bool *)kp->arg;
323 	else
324 		val = *(int *)kp->arg;
325 
326 	/* Y and N chosen as being relatively non-coder friendly */
327 	return sprintf(buffer, "%c", val ? 'Y' : 'N');
328 }
329 EXPORT_SYMBOL(param_get_bool);
330 
331 struct kernel_param_ops param_ops_bool = {
332 	.set = param_set_bool,
333 	.get = param_get_bool,
334 };
335 EXPORT_SYMBOL(param_ops_bool);
336 
337 /* This one must be bool. */
338 int param_set_invbool(const char *val, const struct kernel_param *kp)
339 {
340 	int ret;
341 	bool boolval;
342 	struct kernel_param dummy;
343 
344 	dummy.arg = &boolval;
345 	dummy.flags = KPARAM_ISBOOL;
346 	ret = param_set_bool(val, &dummy);
347 	if (ret == 0)
348 		*(bool *)kp->arg = !boolval;
349 	return ret;
350 }
351 EXPORT_SYMBOL(param_set_invbool);
352 
353 int param_get_invbool(char *buffer, const struct kernel_param *kp)
354 {
355 	return sprintf(buffer, "%c", (*(bool *)kp->arg) ? 'N' : 'Y');
356 }
357 EXPORT_SYMBOL(param_get_invbool);
358 
359 struct kernel_param_ops param_ops_invbool = {
360 	.set = param_set_invbool,
361 	.get = param_get_invbool,
362 };
363 EXPORT_SYMBOL(param_ops_invbool);
364 
365 /* We break the rule and mangle the string. */
366 static int param_array(const char *name,
367 		       const char *val,
368 		       unsigned int min, unsigned int max,
369 		       void *elem, int elemsize,
370 		       int (*set)(const char *, const struct kernel_param *kp),
371 		       u16 flags,
372 		       unsigned int *num)
373 {
374 	int ret;
375 	struct kernel_param kp;
376 	char save;
377 
378 	/* Get the name right for errors. */
379 	kp.name = name;
380 	kp.arg = elem;
381 	kp.flags = flags;
382 
383 	*num = 0;
384 	/* We expect a comma-separated list of values. */
385 	do {
386 		int len;
387 
388 		if (*num == max) {
389 			printk(KERN_ERR "%s: can only take %i arguments\n",
390 			       name, max);
391 			return -EINVAL;
392 		}
393 		len = strcspn(val, ",");
394 
395 		/* nul-terminate and parse */
396 		save = val[len];
397 		((char *)val)[len] = '\0';
398 		BUG_ON(!mutex_is_locked(&param_lock));
399 		ret = set(val, &kp);
400 
401 		if (ret != 0)
402 			return ret;
403 		kp.arg += elemsize;
404 		val += len+1;
405 		(*num)++;
406 	} while (save == ',');
407 
408 	if (*num < min) {
409 		printk(KERN_ERR "%s: needs at least %i arguments\n",
410 		       name, min);
411 		return -EINVAL;
412 	}
413 	return 0;
414 }
415 
416 static int param_array_set(const char *val, const struct kernel_param *kp)
417 {
418 	const struct kparam_array *arr = kp->arr;
419 	unsigned int temp_num;
420 
421 	return param_array(kp->name, val, 1, arr->max, arr->elem,
422 			   arr->elemsize, arr->ops->set, kp->flags,
423 			   arr->num ?: &temp_num);
424 }
425 
426 static int param_array_get(char *buffer, const struct kernel_param *kp)
427 {
428 	int i, off, ret;
429 	const struct kparam_array *arr = kp->arr;
430 	struct kernel_param p;
431 
432 	p = *kp;
433 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
434 		if (i)
435 			buffer[off++] = ',';
436 		p.arg = arr->elem + arr->elemsize * i;
437 		BUG_ON(!mutex_is_locked(&param_lock));
438 		ret = arr->ops->get(buffer + off, &p);
439 		if (ret < 0)
440 			return ret;
441 		off += ret;
442 	}
443 	buffer[off] = '\0';
444 	return off;
445 }
446 
447 static void param_array_free(void *arg)
448 {
449 	unsigned int i;
450 	const struct kparam_array *arr = arg;
451 
452 	if (arr->ops->free)
453 		for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
454 			arr->ops->free(arr->elem + arr->elemsize * i);
455 }
456 
457 struct kernel_param_ops param_array_ops = {
458 	.set = param_array_set,
459 	.get = param_array_get,
460 	.free = param_array_free,
461 };
462 EXPORT_SYMBOL(param_array_ops);
463 
464 int param_set_copystring(const char *val, const struct kernel_param *kp)
465 {
466 	const struct kparam_string *kps = kp->str;
467 
468 	if (strlen(val)+1 > kps->maxlen) {
469 		printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
470 		       kp->name, kps->maxlen-1);
471 		return -ENOSPC;
472 	}
473 	strcpy(kps->string, val);
474 	return 0;
475 }
476 EXPORT_SYMBOL(param_set_copystring);
477 
478 int param_get_string(char *buffer, const struct kernel_param *kp)
479 {
480 	const struct kparam_string *kps = kp->str;
481 	return strlcpy(buffer, kps->string, kps->maxlen);
482 }
483 EXPORT_SYMBOL(param_get_string);
484 
485 struct kernel_param_ops param_ops_string = {
486 	.set = param_set_copystring,
487 	.get = param_get_string,
488 };
489 EXPORT_SYMBOL(param_ops_string);
490 
491 /* sysfs output in /sys/modules/XYZ/parameters/ */
492 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
493 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
494 
495 extern struct kernel_param __start___param[], __stop___param[];
496 
497 struct param_attribute
498 {
499 	struct module_attribute mattr;
500 	const struct kernel_param *param;
501 };
502 
503 struct module_param_attrs
504 {
505 	unsigned int num;
506 	struct attribute_group grp;
507 	struct param_attribute attrs[0];
508 };
509 
510 #ifdef CONFIG_SYSFS
511 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
512 
513 static ssize_t param_attr_show(struct module_attribute *mattr,
514 			       struct module *mod, char *buf)
515 {
516 	int count;
517 	struct param_attribute *attribute = to_param_attr(mattr);
518 
519 	if (!attribute->param->ops->get)
520 		return -EPERM;
521 
522 	mutex_lock(&param_lock);
523 	count = attribute->param->ops->get(buf, attribute->param);
524 	mutex_unlock(&param_lock);
525 	if (count > 0) {
526 		strcat(buf, "\n");
527 		++count;
528 	}
529 	return count;
530 }
531 
532 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
533 static ssize_t param_attr_store(struct module_attribute *mattr,
534 				struct module *owner,
535 				const char *buf, size_t len)
536 {
537  	int err;
538 	struct param_attribute *attribute = to_param_attr(mattr);
539 
540 	if (!attribute->param->ops->set)
541 		return -EPERM;
542 
543 	mutex_lock(&param_lock);
544 	err = attribute->param->ops->set(buf, attribute->param);
545 	mutex_unlock(&param_lock);
546 	if (!err)
547 		return len;
548 	return err;
549 }
550 #endif
551 
552 #ifdef CONFIG_MODULES
553 #define __modinit
554 #else
555 #define __modinit __init
556 #endif
557 
558 #ifdef CONFIG_SYSFS
559 void __kernel_param_lock(void)
560 {
561 	mutex_lock(&param_lock);
562 }
563 EXPORT_SYMBOL(__kernel_param_lock);
564 
565 void __kernel_param_unlock(void)
566 {
567 	mutex_unlock(&param_lock);
568 }
569 EXPORT_SYMBOL(__kernel_param_unlock);
570 
571 /*
572  * add_sysfs_param - add a parameter to sysfs
573  * @mk: struct module_kobject
574  * @kparam: the actual parameter definition to add to sysfs
575  * @name: name of parameter
576  *
577  * Create a kobject if for a (per-module) parameter if mp NULL, and
578  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
579  * if there's an error.
580  */
581 static __modinit int add_sysfs_param(struct module_kobject *mk,
582 				     const struct kernel_param *kp,
583 				     const char *name)
584 {
585 	struct module_param_attrs *new;
586 	struct attribute **attrs;
587 	int err, num;
588 
589 	/* We don't bother calling this with invisible parameters. */
590 	BUG_ON(!kp->perm);
591 
592 	if (!mk->mp) {
593 		num = 0;
594 		attrs = NULL;
595 	} else {
596 		num = mk->mp->num;
597 		attrs = mk->mp->grp.attrs;
598 	}
599 
600 	/* Enlarge. */
601 	new = krealloc(mk->mp,
602 		       sizeof(*mk->mp) + sizeof(mk->mp->attrs[0]) * (num+1),
603 		       GFP_KERNEL);
604 	if (!new) {
605 		kfree(mk->mp);
606 		err = -ENOMEM;
607 		goto fail;
608 	}
609 	attrs = krealloc(attrs, sizeof(new->grp.attrs[0])*(num+2), GFP_KERNEL);
610 	if (!attrs) {
611 		err = -ENOMEM;
612 		goto fail_free_new;
613 	}
614 
615 	/* Sysfs wants everything zeroed. */
616 	memset(new, 0, sizeof(*new));
617 	memset(&new->attrs[num], 0, sizeof(new->attrs[num]));
618 	memset(&attrs[num], 0, sizeof(attrs[num]));
619 	new->grp.name = "parameters";
620 	new->grp.attrs = attrs;
621 
622 	/* Tack new one on the end. */
623 	sysfs_attr_init(&new->attrs[num].mattr.attr);
624 	new->attrs[num].param = kp;
625 	new->attrs[num].mattr.show = param_attr_show;
626 	new->attrs[num].mattr.store = param_attr_store;
627 	new->attrs[num].mattr.attr.name = (char *)name;
628 	new->attrs[num].mattr.attr.mode = kp->perm;
629 	new->num = num+1;
630 
631 	/* Fix up all the pointers, since krealloc can move us */
632 	for (num = 0; num < new->num; num++)
633 		new->grp.attrs[num] = &new->attrs[num].mattr.attr;
634 	new->grp.attrs[num] = NULL;
635 
636 	mk->mp = new;
637 	return 0;
638 
639 fail_free_new:
640 	kfree(new);
641 fail:
642 	mk->mp = NULL;
643 	return err;
644 }
645 
646 #ifdef CONFIG_MODULES
647 static void free_module_param_attrs(struct module_kobject *mk)
648 {
649 	kfree(mk->mp->grp.attrs);
650 	kfree(mk->mp);
651 	mk->mp = NULL;
652 }
653 
654 /*
655  * module_param_sysfs_setup - setup sysfs support for one module
656  * @mod: module
657  * @kparam: module parameters (array)
658  * @num_params: number of module parameters
659  *
660  * Adds sysfs entries for module parameters under
661  * /sys/module/[mod->name]/parameters/
662  */
663 int module_param_sysfs_setup(struct module *mod,
664 			     const struct kernel_param *kparam,
665 			     unsigned int num_params)
666 {
667 	int i, err;
668 	bool params = false;
669 
670 	for (i = 0; i < num_params; i++) {
671 		if (kparam[i].perm == 0)
672 			continue;
673 		err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
674 		if (err)
675 			return err;
676 		params = true;
677 	}
678 
679 	if (!params)
680 		return 0;
681 
682 	/* Create the param group. */
683 	err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
684 	if (err)
685 		free_module_param_attrs(&mod->mkobj);
686 	return err;
687 }
688 
689 /*
690  * module_param_sysfs_remove - remove sysfs support for one module
691  * @mod: module
692  *
693  * Remove sysfs entries for module parameters and the corresponding
694  * kobject.
695  */
696 void module_param_sysfs_remove(struct module *mod)
697 {
698 	if (mod->mkobj.mp) {
699 		sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
700 		/* We are positive that no one is using any param
701 		 * attrs at this point.  Deallocate immediately. */
702 		free_module_param_attrs(&mod->mkobj);
703 	}
704 }
705 #endif
706 
707 void destroy_params(const struct kernel_param *params, unsigned num)
708 {
709 	unsigned int i;
710 
711 	for (i = 0; i < num; i++)
712 		if (params[i].ops->free)
713 			params[i].ops->free(params[i].arg);
714 }
715 
716 static struct module_kobject * __init locate_module_kobject(const char *name)
717 {
718 	struct module_kobject *mk;
719 	struct kobject *kobj;
720 	int err;
721 
722 	kobj = kset_find_obj(module_kset, name);
723 	if (kobj) {
724 		mk = to_module_kobject(kobj);
725 	} else {
726 		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
727 		BUG_ON(!mk);
728 
729 		mk->mod = THIS_MODULE;
730 		mk->kobj.kset = module_kset;
731 		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
732 					   "%s", name);
733 		if (err) {
734 			kobject_put(&mk->kobj);
735 			printk(KERN_ERR
736 				"Module '%s' failed add to sysfs, error number %d\n",
737 				name, err);
738 			printk(KERN_ERR
739 				"The system will be unstable now.\n");
740 			return NULL;
741 		}
742 
743 		/* So that we hold reference in both cases. */
744 		kobject_get(&mk->kobj);
745 	}
746 
747 	return mk;
748 }
749 
750 static void __init kernel_add_sysfs_param(const char *name,
751 					  struct kernel_param *kparam,
752 					  unsigned int name_skip)
753 {
754 	struct module_kobject *mk;
755 	int err;
756 
757 	mk = locate_module_kobject(name);
758 	if (!mk)
759 		return;
760 
761 	/* We need to remove old parameters before adding more. */
762 	if (mk->mp)
763 		sysfs_remove_group(&mk->kobj, &mk->mp->grp);
764 
765 	/* These should not fail at boot. */
766 	err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
767 	BUG_ON(err);
768 	err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
769 	BUG_ON(err);
770 	kobject_uevent(&mk->kobj, KOBJ_ADD);
771 	kobject_put(&mk->kobj);
772 }
773 
774 /*
775  * param_sysfs_builtin - add contents in /sys/parameters for built-in modules
776  *
777  * Add module_parameters to sysfs for "modules" built into the kernel.
778  *
779  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
780  * "parameter" name is stored behind a dot in kernel_param->name. So,
781  * extract the "module" name for all built-in kernel_param-eters,
782  * and for all who have the same, call kernel_add_sysfs_param.
783  */
784 static void __init param_sysfs_builtin(void)
785 {
786 	struct kernel_param *kp;
787 	unsigned int name_len;
788 	char modname[MODULE_NAME_LEN];
789 
790 	for (kp = __start___param; kp < __stop___param; kp++) {
791 		char *dot;
792 
793 		if (kp->perm == 0)
794 			continue;
795 
796 		dot = strchr(kp->name, '.');
797 		if (!dot) {
798 			/* This happens for core_param() */
799 			strcpy(modname, "kernel");
800 			name_len = 0;
801 		} else {
802 			name_len = dot - kp->name + 1;
803 			strlcpy(modname, kp->name, name_len);
804 		}
805 		kernel_add_sysfs_param(modname, kp, name_len);
806 	}
807 }
808 
809 ssize_t __modver_version_show(struct module_attribute *mattr,
810 			      struct module *mod, char *buf)
811 {
812 	struct module_version_attribute *vattr =
813 		container_of(mattr, struct module_version_attribute, mattr);
814 
815 	return sprintf(buf, "%s\n", vattr->version);
816 }
817 
818 extern const struct module_version_attribute *__start___modver[];
819 extern const struct module_version_attribute *__stop___modver[];
820 
821 static void __init version_sysfs_builtin(void)
822 {
823 	const struct module_version_attribute **p;
824 	struct module_kobject *mk;
825 	int err;
826 
827 	for (p = __start___modver; p < __stop___modver; p++) {
828 		const struct module_version_attribute *vattr = *p;
829 
830 		mk = locate_module_kobject(vattr->module_name);
831 		if (mk) {
832 			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
833 			kobject_uevent(&mk->kobj, KOBJ_ADD);
834 			kobject_put(&mk->kobj);
835 		}
836 	}
837 }
838 
839 /* module-related sysfs stuff */
840 
841 static ssize_t module_attr_show(struct kobject *kobj,
842 				struct attribute *attr,
843 				char *buf)
844 {
845 	struct module_attribute *attribute;
846 	struct module_kobject *mk;
847 	int ret;
848 
849 	attribute = to_module_attr(attr);
850 	mk = to_module_kobject(kobj);
851 
852 	if (!attribute->show)
853 		return -EIO;
854 
855 	ret = attribute->show(attribute, mk->mod, buf);
856 
857 	return ret;
858 }
859 
860 static ssize_t module_attr_store(struct kobject *kobj,
861 				struct attribute *attr,
862 				const char *buf, size_t len)
863 {
864 	struct module_attribute *attribute;
865 	struct module_kobject *mk;
866 	int ret;
867 
868 	attribute = to_module_attr(attr);
869 	mk = to_module_kobject(kobj);
870 
871 	if (!attribute->store)
872 		return -EIO;
873 
874 	ret = attribute->store(attribute, mk->mod, buf, len);
875 
876 	return ret;
877 }
878 
879 static const struct sysfs_ops module_sysfs_ops = {
880 	.show = module_attr_show,
881 	.store = module_attr_store,
882 };
883 
884 static int uevent_filter(struct kset *kset, struct kobject *kobj)
885 {
886 	struct kobj_type *ktype = get_ktype(kobj);
887 
888 	if (ktype == &module_ktype)
889 		return 1;
890 	return 0;
891 }
892 
893 static const struct kset_uevent_ops module_uevent_ops = {
894 	.filter = uevent_filter,
895 };
896 
897 struct kset *module_kset;
898 int module_sysfs_initialized;
899 
900 struct kobj_type module_ktype = {
901 	.sysfs_ops =	&module_sysfs_ops,
902 };
903 
904 /*
905  * param_sysfs_init - wrapper for built-in params support
906  */
907 static int __init param_sysfs_init(void)
908 {
909 	module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
910 	if (!module_kset) {
911 		printk(KERN_WARNING "%s (%d): error creating kset\n",
912 			__FILE__, __LINE__);
913 		return -ENOMEM;
914 	}
915 	module_sysfs_initialized = 1;
916 
917 	version_sysfs_builtin();
918 	param_sysfs_builtin();
919 
920 	return 0;
921 }
922 subsys_initcall(param_sysfs_init);
923 
924 #endif /* CONFIG_SYSFS */
925