kernel/params.c

   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/kernel.h>
  19 #include <linux/string.h>
  20 #include <linux/errno.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/device.h>
  24 #include <linux/err.h>
  25 #include <linux/slab.h>
  26 #include <linux/ctype.h>
  27
  28 #ifdef CONFIG_SYSFS
  29 /* Protects all built-in parameters, modules use their own param_lock */
  30 static DEFINE_MUTEX(param_lock);
  31
  32 /* Use the module's mutex, or if built-in use the built-in mutex */
  33 #ifdef CONFIG_MODULES
  34 #define KPARAM_MUTEX(mod)       ((mod) ? &(mod)->param_lock : &param_lock)
  35 #else
  36 #define KPARAM_MUTEX(mod)       (&param_lock)
  37 #endif
  38
  39 static inline void check_kparam_locked(struct module *mod)
  40 {
  41         BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
  42 }
  43 #else
  44 static inline void check_kparam_locked(struct module *mod)
  45 {
  46 }
  47 #endif /* !CONFIG_SYSFS */
  48
  49 /* This just allows us to keep track of which parameters are kmalloced. */
  50 struct kmalloced_param {
  51         struct list_head list;
  52         char val[];
  53 };
  54 static LIST_HEAD(kmalloced_params);
  55 static DEFINE_SPINLOCK(kmalloced_params_lock);
  56
  57 static void *kmalloc_parameter(unsigned int size)
  58 {
  59         struct kmalloced_param *p;
  60
  61         p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
  62         if (!p)
  63                 return NULL;
  64
  65         spin_lock(&kmalloced_params_lock);
  66         list_add(&p->list, &kmalloced_params);
  67         spin_unlock(&kmalloced_params_lock);
  68
  69         return p->val;
  70 }
  71
  72 /* Does nothing if parameter wasn't kmalloced above. */
  73 static void maybe_kfree_parameter(void *param)
  74 {
  75         struct kmalloced_param *p;
  76
  77         spin_lock(&kmalloced_params_lock);
  78         list_for_each_entry(p, &kmalloced_params, list) {
  79                 if (p->val == param) {
  80                         list_del(&p->list);
  81                         kfree(p);
  82                         break;
  83                 }
  84         }
  85         spin_unlock(&kmalloced_params_lock);
  86 }
  87
  88 static char dash2underscore(char c)
  89 {
  90         if (c == '-')
  91                 return '_';
  92         return c;
  93 }
  94
  95 bool parameqn(const char *a, const char *b, size_t n)
  96 {
  97         size_t i;
  98
  99         for (i = 0; i < n; i++) {
 100                 if (dash2underscore(a[i]) != dash2underscore(b[i]))
 101                         return false;
 102         }
 103         return true;
 104 }
 105
 106 bool parameq(const char *a, const char *b)
 107 {
 108         return parameqn(a, b, strlen(a)+1);
 109 }
 110
 111 static void param_check_unsafe(const struct kernel_param *kp)
 112 {
 113         if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
 114                 pr_warn("Setting dangerous option %s - tainting kernel\n",
 115                         kp->name);
 116                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 117         }
 118 }
 119
 120 static int parse_one(char *param,
 121                      char *val,
 122                      const char *doing,
 123                      const struct kernel_param *params,
 124                      unsigned num_params,
 125                      s16 min_level,
 126                      s16 max_level,
 127                      void *arg,
 128                      int (*handle_unknown)(char *param, char *val,
 129                                      const char *doing, void *arg))
 130 {
 131         unsigned int i;
 132         int err;
 133
 134         /* Find parameter */
 135         for (i = 0; i < num_params; i++) {
 136                 if (parameq(param, params[i].name)) {
 137                         if (params[i].level < min_level
 138                             || params[i].level > max_level)
 139                                 return 0;
 140                         /* No one handled NULL, so do it here. */
 141                         if (!val &&
 142                             !(params[i].ops->flags & KERNEL_PARAM_OPS_FL_NOARG))
 143                                 return -EINVAL;
 144                         pr_debug("handling %s with %p\n", param,
 145                                 params[i].ops->set);
 146                         kernel_param_lock(params[i].mod);
 147                         param_check_unsafe(&params[i]);
 148                         err = params[i].ops->set(val, &params[i]);
 149                         kernel_param_unlock(params[i].mod);
 150                         return err;
 151                 }
 152         }
 153
 154         if (handle_unknown) {
 155                 pr_debug("doing %s: %s='%s'\n", doing, param, val);
 156                 return handle_unknown(param, val, doing, arg);
 157         }
 158
 159         pr_debug("Unknown argument '%s'\n", param);
 160         return -ENOENT;
 161 }
 162
 163 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
 164 char *parse_args(const char *doing,
 165                  char *args,
 166                  const struct kernel_param *params,
 167                  unsigned num,
 168                  s16 min_level,
 169                  s16 max_level,
 170                  void *arg,
 171                  int (*unknown)(char *param, char *val,
 172                                 const char *doing, void *arg))
 173 {
 174         char *param, *val, *err = NULL;
 175
 176         /* Chew leading spaces */
 177         args = skip_spaces(args);
 178
 179         if (*args)
 180                 pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);
 181
 182         while (*args) {
 183                 int ret;
 184                 int irq_was_disabled;
 185
 186                 args = next_arg(args, &param, &val);
 187                 /* Stop at -- */
 188                 if (!val && strcmp(param, "--") == 0)
 189                         return err ?: args;
 190                 irq_was_disabled = irqs_disabled();
 191                 ret = parse_one(param, val, doing, params, num,
 192                                 min_level, max_level, arg, unknown);
 193                 if (irq_was_disabled && !irqs_disabled())
 194                         pr_warn("%s: option '%s' enabled irq's!\n",
 195                                 doing, param);
 196
 197                 switch (ret) {
 198                 case 0:
 199                         continue;
 200                 case -ENOENT:
 201                         pr_err("%s: Unknown parameter `%s'\n", doing, param);
 202                         break;
 203                 case -ENOSPC:
 204                         pr_err("%s: `%s' too large for parameter `%s'\n",
 205                                doing, val ?: "", param);
 206                         break;
 207                 default:
 208                         pr_err("%s: `%s' invalid for parameter `%s'\n",
 209                                doing, val ?: "", param);
 210                         break;
 211                 }
 212
 213                 err = ERR_PTR(ret);
 214         }
 215
 216         return err;
 217 }
 218
 219 /* Lazy bastard, eh? */
 220 #define STANDARD_PARAM_DEF(name, type, format, strtolfn)                \
 221         int param_set_##name(const char *val, const struct kernel_param *kp) \
 222         {                                                               \
 223                 return strtolfn(val, 0, (type *)kp->arg);               \
 224         }                                                               \
 225         int param_get_##name(char *buffer, const struct kernel_param *kp) \
 226         {                                                               \
 227                 return scnprintf(buffer, PAGE_SIZE, format "\n",        \
 228                                 *((type *)kp->arg));                    \
 229         }                                                               \
 230         const struct kernel_param_ops param_ops_##name = {                      \
 231                 .set = param_set_##name,                                \
 232                 .get = param_get_##name,                                \
 233         };                                                              \
 234         EXPORT_SYMBOL(param_set_##name);                                \
 235         EXPORT_SYMBOL(param_get_##name);                                \
 236         EXPORT_SYMBOL(param_ops_##name)
 237
 238
 239 STANDARD_PARAM_DEF(byte,        unsigned char,          "%hhu", kstrtou8);
 240 STANDARD_PARAM_DEF(short,       short,                  "%hi",  kstrtos16);
 241 STANDARD_PARAM_DEF(ushort,      unsigned short,         "%hu",  kstrtou16);
 242 STANDARD_PARAM_DEF(int,         int,                    "%i",   kstrtoint);
 243 STANDARD_PARAM_DEF(uint,        unsigned int,           "%u",   kstrtouint);
 244 STANDARD_PARAM_DEF(long,        long,                   "%li",  kstrtol);
 245 STANDARD_PARAM_DEF(ulong,       unsigned long,          "%lu",  kstrtoul);
 246 STANDARD_PARAM_DEF(ullong,      unsigned long long,     "%llu", kstrtoull);
 247
 248 int param_set_charp(const char *val, const struct kernel_param *kp)
 249 {
 250         if (strlen(val) > 1024) {
 251                 pr_err("%s: string parameter too long\n", kp->name);
 252                 return -ENOSPC;
 253         }
 254
 255         maybe_kfree_parameter(*(char **)kp->arg);
 256
 257         /* This is a hack.  We can't kmalloc in early boot, and we
 258          * don't need to; this mangled commandline is preserved. */
 259         if (slab_is_available()) {
 260                 *(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
 261                 if (!*(char **)kp->arg)
 262                         return -ENOMEM;
 263                 strcpy(*(char **)kp->arg, val);
 264         } else
 265                 *(const char **)kp->arg = val;
 266
 267         return 0;
 268 }
 269 EXPORT_SYMBOL(param_set_charp);
 270
 271 int param_get_charp(char *buffer, const struct kernel_param *kp)
 272 {
 273         return scnprintf(buffer, PAGE_SIZE, "%s\n", *((char **)kp->arg));
 274 }
 275 EXPORT_SYMBOL(param_get_charp);
 276
 277 void param_free_charp(void *arg)
 278 {
 279         maybe_kfree_parameter(*((char **)arg));
 280 }
 281 EXPORT_SYMBOL(param_free_charp);
 282
 283 const struct kernel_param_ops param_ops_charp = {
 284         .set = param_set_charp,
 285         .get = param_get_charp,
 286         .free = param_free_charp,
 287 };
 288 EXPORT_SYMBOL(param_ops_charp);
 289
 290 /* Actually could be a bool or an int, for historical reasons. */
 291 int param_set_bool(const char *val, const struct kernel_param *kp)
 292 {
 293         /* No equals means "set"... */
 294         if (!val) val = "1";
 295
 296         /* One of =[yYnN01] */
 297         return strtobool(val, kp->arg);
 298 }
 299 EXPORT_SYMBOL(param_set_bool);
 300
 301 int param_get_bool(char *buffer, const struct kernel_param *kp)
 302 {
 303         /* Y and N chosen as being relatively non-coder friendly */
 304         return sprintf(buffer, "%c\n", *(bool *)kp->arg ? 'Y' : 'N');
 305 }
 306 EXPORT_SYMBOL(param_get_bool);
 307
 308 const struct kernel_param_ops param_ops_bool = {
 309         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 310         .set = param_set_bool,
 311         .get = param_get_bool,
 312 };
 313 EXPORT_SYMBOL(param_ops_bool);
 314
 315 int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
 316 {
 317         int err = 0;
 318         bool new_value;
 319         bool orig_value = *(bool *)kp->arg;
 320         struct kernel_param dummy_kp = *kp;
 321
 322         dummy_kp.arg = &new_value;
 323
 324         err = param_set_bool(val, &dummy_kp);
 325         if (err)
 326                 return err;
 327
 328         /* Don't let them unset it once it's set! */
 329         if (!new_value && orig_value)
 330                 return -EROFS;
 331
 332         if (new_value)
 333                 err = param_set_bool(val, kp);
 334
 335         return err;
 336 }
 337 EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
 338
 339 const struct kernel_param_ops param_ops_bool_enable_only = {
 340         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 341         .set = param_set_bool_enable_only,
 342         .get = param_get_bool,
 343 };
 344 EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
 345
 346 /* This one must be bool. */
 347 int param_set_invbool(const char *val, const struct kernel_param *kp)
 348 {
 349         int ret;
 350         bool boolval;
 351         struct kernel_param dummy;
 352
 353         dummy.arg = &boolval;
 354         ret = param_set_bool(val, &dummy);
 355         if (ret == 0)
 356                 *(bool *)kp->arg = !boolval;
 357         return ret;
 358 }
 359 EXPORT_SYMBOL(param_set_invbool);
 360
 361 int param_get_invbool(char *buffer, const struct kernel_param *kp)
 362 {
 363         return sprintf(buffer, "%c\n", (*(bool *)kp->arg) ? 'N' : 'Y');
 364 }
 365 EXPORT_SYMBOL(param_get_invbool);
 366
 367 const struct kernel_param_ops param_ops_invbool = {
 368         .set = param_set_invbool,
 369         .get = param_get_invbool,
 370 };
 371 EXPORT_SYMBOL(param_ops_invbool);
 372
 373 int param_set_bint(const char *val, const struct kernel_param *kp)
 374 {
 375         /* Match bool exactly, by re-using it. */
 376         struct kernel_param boolkp = *kp;
 377         bool v;
 378         int ret;
 379
 380         boolkp.arg = &v;
 381
 382         ret = param_set_bool(val, &boolkp);
 383         if (ret == 0)
 384                 *(int *)kp->arg = v;
 385         return ret;
 386 }
 387 EXPORT_SYMBOL(param_set_bint);
 388
 389 const struct kernel_param_ops param_ops_bint = {
 390         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 391         .set = param_set_bint,
 392         .get = param_get_int,
 393 };
 394 EXPORT_SYMBOL(param_ops_bint);
 395
 396 /* We break the rule and mangle the string. */
 397 static int param_array(struct module *mod,
 398                        const char *name,
 399                        const char *val,
 400                        unsigned int min, unsigned int max,
 401                        void *elem, int elemsize,
 402                        int (*set)(const char *, const struct kernel_param *kp),
 403                        s16 level,
 404                        unsigned int *num)
 405 {
 406         int ret;
 407         struct kernel_param kp;
 408         char save;
 409
 410         /* Get the name right for errors. */
 411         kp.name = name;
 412         kp.arg = elem;
 413         kp.level = level;
 414
 415         *num = 0;
 416         /* We expect a comma-separated list of values. */
 417         do {
 418                 int len;
 419
 420                 if (*num == max) {
 421                         pr_err("%s: can only take %i arguments\n", name, max);
 422                         return -EINVAL;
 423                 }
 424                 len = strcspn(val, ",");
 425
 426                 /* nul-terminate and parse */
 427                 save = val[len];
 428                 ((char *)val)[len] = '\0';
 429                 check_kparam_locked(mod);
 430                 ret = set(val, &kp);
 431
 432                 if (ret != 0)
 433                         return ret;
 434                 kp.arg += elemsize;
 435                 val += len+1;
 436                 (*num)++;
 437         } while (save == ',');
 438
 439         if (*num < min) {
 440                 pr_err("%s: needs at least %i arguments\n", name, min);
 441                 return -EINVAL;
 442         }
 443         return 0;
 444 }
 445
 446 static int param_array_set(const char *val, const struct kernel_param *kp)
 447 {
 448         const struct kparam_array *arr = kp->arr;
 449         unsigned int temp_num;
 450
 451         return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
 452                            arr->elemsize, arr->ops->set, kp->level,
 453                            arr->num ?: &temp_num);
 454 }
 455
 456 static int param_array_get(char *buffer, const struct kernel_param *kp)
 457 {
 458         int i, off, ret;
 459         const struct kparam_array *arr = kp->arr;
 460         struct kernel_param p = *kp;
 461
 462         for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
 463                 /* Replace \n with comma */
 464                 if (i)
 465                         buffer[off - 1] = ',';
 466                 p.arg = arr->elem + arr->elemsize * i;
 467                 check_kparam_locked(p.mod);
 468                 ret = arr->ops->get(buffer + off, &p);
 469                 if (ret < 0)
 470                         return ret;
 471                 off += ret;
 472         }
 473         buffer[off] = '\0';
 474         return off;
 475 }
 476
 477 static void param_array_free(void *arg)
 478 {
 479         unsigned int i;
 480         const struct kparam_array *arr = arg;
 481
 482         if (arr->ops->free)
 483                 for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
 484                         arr->ops->free(arr->elem + arr->elemsize * i);
 485 }
 486
 487 const struct kernel_param_ops param_array_ops = {
 488         .set = param_array_set,
 489         .get = param_array_get,
 490         .free = param_array_free,
 491 };
 492 EXPORT_SYMBOL(param_array_ops);
 493
 494 int param_set_copystring(const char *val, const struct kernel_param *kp)
 495 {
 496         const struct kparam_string *kps = kp->str;
 497
 498         if (strlen(val)+1 > kps->maxlen) {
 499                 pr_err("%s: string doesn't fit in %u chars.\n",
 500                        kp->name, kps->maxlen-1);
 501                 return -ENOSPC;
 502         }
 503         strcpy(kps->string, val);
 504         return 0;
 505 }
 506 EXPORT_SYMBOL(param_set_copystring);
 507
 508 int param_get_string(char *buffer, const struct kernel_param *kp)
 509 {
 510         const struct kparam_string *kps = kp->str;
 511         return scnprintf(buffer, PAGE_SIZE, "%s\n", kps->string);
 512 }
 513 EXPORT_SYMBOL(param_get_string);
 514
 515 const struct kernel_param_ops param_ops_string = {
 516         .set = param_set_copystring,
 517         .get = param_get_string,
 518 };
 519 EXPORT_SYMBOL(param_ops_string);
 520
 521 /* sysfs output in /sys/modules/XYZ/parameters/ */
 522 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
 523 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
 524
 525 struct param_attribute
 526 {
 527         struct module_attribute mattr;
 528         const struct kernel_param *param;
 529 };
 530
 531 struct module_param_attrs
 532 {
 533         unsigned int num;
 534         struct attribute_group grp;
 535         struct param_attribute attrs[0];
 536 };
 537
 538 #ifdef CONFIG_SYSFS
 539 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
 540
 541 static ssize_t param_attr_show(struct module_attribute *mattr,
 542                                struct module_kobject *mk, char *buf)
 543 {
 544         int count;
 545         struct param_attribute *attribute = to_param_attr(mattr);
 546
 547         if (!attribute->param->ops->get)
 548                 return -EPERM;
 549
 550         kernel_param_lock(mk->mod);
 551         count = attribute->param->ops->get(buf, attribute->param);
 552         kernel_param_unlock(mk->mod);
 553         return count;
 554 }
 555
 556 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 557 static ssize_t param_attr_store(struct module_attribute *mattr,
 558                                 struct module_kobject *mk,
 559                                 const char *buf, size_t len)
 560 {
 561         int err;
 562         struct param_attribute *attribute = to_param_attr(mattr);
 563
 564         if (!attribute->param->ops->set)
 565                 return -EPERM;
 566
 567         kernel_param_lock(mk->mod);
 568         param_check_unsafe(attribute->param);
 569         err = attribute->param->ops->set(buf, attribute->param);
 570         kernel_param_unlock(mk->mod);
 571         if (!err)
 572                 return len;
 573         return err;
 574 }
 575 #endif
 576
 577 #ifdef CONFIG_MODULES
 578 #define __modinit
 579 #else
 580 #define __modinit __init
 581 #endif
 582
 583 #ifdef CONFIG_SYSFS
 584 void kernel_param_lock(struct module *mod)
 585 {
 586         mutex_lock(KPARAM_MUTEX(mod));
 587 }
 588
 589 void kernel_param_unlock(struct module *mod)
 590 {
 591         mutex_unlock(KPARAM_MUTEX(mod));
 592 }
 593
 594 EXPORT_SYMBOL(kernel_param_lock);
 595 EXPORT_SYMBOL(kernel_param_unlock);
 596
 597 /*
 598  * add_sysfs_param - add a parameter to sysfs
 599  * @mk: struct module_kobject
 600  * @kp: the actual parameter definition to add to sysfs
 601  * @name: name of parameter
 602  *
 603  * Create a kobject if for a (per-module) parameter if mp NULL, and
 604  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
 605  * if there's an error.
 606  */
 607 static __modinit int add_sysfs_param(struct module_kobject *mk,
 608                                      const struct kernel_param *kp,
 609                                      const char *name)
 610 {
 611         struct module_param_attrs *new_mp;
 612         struct attribute **new_attrs;
 613         unsigned int i;
 614
 615         /* We don't bother calling this with invisible parameters. */
 616         BUG_ON(!kp->perm);
 617
 618         if (!mk->mp) {
 619                 /* First allocation. */
 620                 mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
 621                 if (!mk->mp)
 622                         return -ENOMEM;
 623                 mk->mp->grp.name = "parameters";
 624                 /* NULL-terminated attribute array. */
 625                 mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
 626                                             GFP_KERNEL);
 627                 /* Caller will cleanup via free_module_param_attrs */
 628                 if (!mk->mp->grp.attrs)
 629                         return -ENOMEM;
 630         }
 631
 632         /* Enlarge allocations. */
 633         new_mp = krealloc(mk->mp,
 634                           sizeof(*mk->mp) +
 635                           sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
 636                           GFP_KERNEL);
 637         if (!new_mp)
 638                 return -ENOMEM;
 639         mk->mp = new_mp;
 640
 641         /* Extra pointer for NULL terminator */
 642         new_attrs = krealloc(mk->mp->grp.attrs,
 643                              sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
 644                              GFP_KERNEL);
 645         if (!new_attrs)
 646                 return -ENOMEM;
 647         mk->mp->grp.attrs = new_attrs;
 648
 649         /* Tack new one on the end. */
 650         memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
 651         sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
 652         mk->mp->attrs[mk->mp->num].param = kp;
 653         mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
 654         /* Do not allow runtime DAC changes to make param writable. */
 655         if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
 656                 mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
 657         else
 658                 mk->mp->attrs[mk->mp->num].mattr.store = NULL;
 659         mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
 660         mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
 661         mk->mp->num++;
 662
 663         /* Fix up all the pointers, since krealloc can move us */
 664         for (i = 0; i < mk->mp->num; i++)
 665                 mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
 666         mk->mp->grp.attrs[mk->mp->num] = NULL;
 667         return 0;
 668 }
 669
 670 #ifdef CONFIG_MODULES
 671 static void free_module_param_attrs(struct module_kobject *mk)
 672 {
 673         if (mk->mp)
 674                 kfree(mk->mp->grp.attrs);
 675         kfree(mk->mp);
 676         mk->mp = NULL;
 677 }
 678
 679 /*
 680  * module_param_sysfs_setup - setup sysfs support for one module
 681  * @mod: module
 682  * @kparam: module parameters (array)
 683  * @num_params: number of module parameters
 684  *
 685  * Adds sysfs entries for module parameters under
 686  * /sys/module/[mod->name]/parameters/
 687  */
 688 int module_param_sysfs_setup(struct module *mod,
 689                              const struct kernel_param *kparam,
 690                              unsigned int num_params)
 691 {
 692         int i, err;
 693         bool params = false;
 694
 695         for (i = 0; i < num_params; i++) {
 696                 if (kparam[i].perm == 0)
 697                         continue;
 698                 err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
 699                 if (err) {
 700                         free_module_param_attrs(&mod->mkobj);
 701                         return err;
 702                 }
 703                 params = true;
 704         }
 705
 706         if (!params)
 707                 return 0;
 708
 709         /* Create the param group. */
 710         err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 711         if (err)
 712                 free_module_param_attrs(&mod->mkobj);
 713         return err;
 714 }
 715
 716 /*
 717  * module_param_sysfs_remove - remove sysfs support for one module
 718  * @mod: module
 719  *
 720  * Remove sysfs entries for module parameters and the corresponding
 721  * kobject.
 722  */
 723 void module_param_sysfs_remove(struct module *mod)
 724 {
 725         if (mod->mkobj.mp) {
 726                 sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 727                 /* We are positive that no one is using any param
 728                  * attrs at this point.  Deallocate immediately. */
 729                 free_module_param_attrs(&mod->mkobj);
 730         }
 731 }
 732 #endif
 733
 734 void destroy_params(const struct kernel_param *params, unsigned num)
 735 {
 736         unsigned int i;
 737
 738         for (i = 0; i < num; i++)
 739                 if (params[i].ops->free)
 740                         params[i].ops->free(params[i].arg);
 741 }
 742
 743 static struct module_kobject * __init locate_module_kobject(const char *name)
 744 {
 745         struct module_kobject *mk;
 746         struct kobject *kobj;
 747         int err;
 748
 749         kobj = kset_find_obj(module_kset, name);
 750         if (kobj) {
 751                 mk = to_module_kobject(kobj);
 752         } else {
 753                 mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
 754                 BUG_ON(!mk);
 755
 756                 mk->mod = THIS_MODULE;
 757                 mk->kobj.kset = module_kset;
 758                 err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
 759                                            "%s", name);
 760 #ifdef CONFIG_MODULES
 761                 if (!err)
 762                         err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
 763 #endif
 764                 if (err) {
 765                         kobject_put(&mk->kobj);
 766                         pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
 767                                 name, err);
 768                         return NULL;
 769                 }
 770
 771                 /* So that we hold reference in both cases. */
 772                 kobject_get(&mk->kobj);
 773         }
 774
 775         return mk;
 776 }
 777
 778 static void __init kernel_add_sysfs_param(const char *name,
 779                                           const struct kernel_param *kparam,
 780                                           unsigned int name_skip)
 781 {
 782         struct module_kobject *mk;
 783         int err;
 784
 785         mk = locate_module_kobject(name);
 786         if (!mk)
 787                 return;
 788
 789         /* We need to remove old parameters before adding more. */
 790         if (mk->mp)
 791                 sysfs_remove_group(&mk->kobj, &mk->mp->grp);
 792
 793         /* These should not fail at boot. */
 794         err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
 795         BUG_ON(err);
 796         err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
 797         BUG_ON(err);
 798         kobject_uevent(&mk->kobj, KOBJ_ADD);
 799         kobject_put(&mk->kobj);
 800 }
 801
 802 /*
 803  * param_sysfs_builtin - add sysfs parameters for built-in modules
 804  *
 805  * Add module_parameters to sysfs for "modules" built into the kernel.
 806  *
 807  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
 808  * "parameter" name is stored behind a dot in kernel_param->name. So,
 809  * extract the "module" name for all built-in kernel_param-eters,
 810  * and for all who have the same, call kernel_add_sysfs_param.
 811  */
 812 static void __init param_sysfs_builtin(void)
 813 {
 814         const struct kernel_param *kp;
 815         unsigned int name_len;
 816         char modname[MODULE_NAME_LEN];
 817
 818         for (kp = __start___param; kp < __stop___param; kp++) {
 819                 char *dot;
 820
 821                 if (kp->perm == 0)
 822                         continue;
 823
 824                 dot = strchr(kp->name, '.');
 825                 if (!dot) {
 826                         /* This happens for core_param() */
 827                         strcpy(modname, "kernel");
 828                         name_len = 0;
 829                 } else {
 830                         name_len = dot - kp->name + 1;
 831                         strlcpy(modname, kp->name, name_len);
 832                 }
 833                 kernel_add_sysfs_param(modname, kp, name_len);
 834         }
 835 }
 836
 837 ssize_t __modver_version_show(struct module_attribute *mattr,
 838                               struct module_kobject *mk, char *buf)
 839 {
 840         struct module_version_attribute *vattr =
 841                 container_of(mattr, struct module_version_attribute, mattr);
 842
 843         return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
 844 }
 845
 846 extern const struct module_version_attribute *__start___modver[];
 847 extern const struct module_version_attribute *__stop___modver[];
 848
 849 static void __init version_sysfs_builtin(void)
 850 {
 851         const struct module_version_attribute **p;
 852         struct module_kobject *mk;
 853         int err;
 854
 855         for (p = __start___modver; p < __stop___modver; p++) {
 856                 const struct module_version_attribute *vattr = *p;
 857
 858                 mk = locate_module_kobject(vattr->module_name);
 859                 if (mk) {
 860                         err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
 861                         WARN_ON_ONCE(err);
 862                         kobject_uevent(&mk->kobj, KOBJ_ADD);
 863                         kobject_put(&mk->kobj);
 864                 }
 865         }
 866 }
 867
 868 /* module-related sysfs stuff */
 869
 870 static ssize_t module_attr_show(struct kobject *kobj,
 871                                 struct attribute *attr,
 872                                 char *buf)
 873 {
 874         struct module_attribute *attribute;
 875         struct module_kobject *mk;
 876         int ret;
 877
 878         attribute = to_module_attr(attr);
 879         mk = to_module_kobject(kobj);
 880
 881         if (!attribute->show)
 882                 return -EIO;
 883
 884         ret = attribute->show(attribute, mk, buf);
 885
 886         return ret;
 887 }
 888
 889 static ssize_t module_attr_store(struct kobject *kobj,
 890                                 struct attribute *attr,
 891                                 const char *buf, size_t len)
 892 {
 893         struct module_attribute *attribute;
 894         struct module_kobject *mk;
 895         int ret;
 896
 897         attribute = to_module_attr(attr);
 898         mk = to_module_kobject(kobj);
 899
 900         if (!attribute->store)
 901                 return -EIO;
 902
 903         ret = attribute->store(attribute, mk, buf, len);
 904
 905         return ret;
 906 }
 907
 908 static const struct sysfs_ops module_sysfs_ops = {
 909         .show = module_attr_show,
 910         .store = module_attr_store,
 911 };
 912
 913 static int uevent_filter(struct kset *kset, struct kobject *kobj)
 914 {
 915         struct kobj_type *ktype = get_ktype(kobj);
 916
 917         if (ktype == &module_ktype)
 918                 return 1;
 919         return 0;
 920 }
 921
 922 static const struct kset_uevent_ops module_uevent_ops = {
 923         .filter = uevent_filter,
 924 };
 925
 926 struct kset *module_kset;
 927 int module_sysfs_initialized;
 928
 929 static void module_kobj_release(struct kobject *kobj)
 930 {
 931         struct module_kobject *mk = to_module_kobject(kobj);
 932         complete(mk->kobj_completion);
 933 }
 934
 935 struct kobj_type module_ktype = {
 936         .release   =    module_kobj_release,
 937         .sysfs_ops =    &module_sysfs_ops,
 938 };
 939
 940 /*
 941  * param_sysfs_init - wrapper for built-in params support
 942  */
 943 static int __init param_sysfs_init(void)
 944 {
 945         module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
 946         if (!module_kset) {
 947                 printk(KERN_WARNING "%s (%d): error creating kset\n",
 948                         __FILE__, __LINE__);
 949                 return -ENOMEM;
 950         }
 951         module_sysfs_initialized = 1;
 952
 953         version_sysfs_builtin();
 954         param_sysfs_builtin();
 955
 956         return 0;
 957 }
 958 subsys_initcall(param_sysfs_init);
 959
 960 #endif /* CONFIG_SYSFS */