kernel/params.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Helpers for initial module or kernel cmdline parsing
   3    Copyright (C) 2001 Rusty Russell.
   4
   5 */
   6 #include <linux/kernel.h>
   7 #include <linux/string.h>
   8 #include <linux/errno.h>
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/device.h>
  12 #include <linux/err.h>
  13 #include <linux/slab.h>
  14 #include <linux/ctype.h>
  15
  16 #ifdef CONFIG_SYSFS
  17 /* Protects all built-in parameters, modules use their own param_lock */
  18 static DEFINE_MUTEX(param_lock);
  19
  20 /* Use the module's mutex, or if built-in use the built-in mutex */
  21 #ifdef CONFIG_MODULES
  22 #define KPARAM_MUTEX(mod)       ((mod) ? &(mod)->param_lock : &param_lock)
  23 #else
  24 #define KPARAM_MUTEX(mod)       (&param_lock)
  25 #endif
  26
  27 static inline void check_kparam_locked(struct module *mod)
  28 {
  29         BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
  30 }
  31 #else
  32 static inline void check_kparam_locked(struct module *mod)
  33 {
  34 }
  35 #endif /* !CONFIG_SYSFS */
  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 static DEFINE_SPINLOCK(kmalloced_params_lock);
  44
  45 static void *kmalloc_parameter(unsigned int size)
  46 {
  47         struct kmalloced_param *p;
  48
  49         p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
  50         if (!p)
  51                 return NULL;
  52
  53         spin_lock(&kmalloced_params_lock);
  54         list_add(&p->list, &kmalloced_params);
  55         spin_unlock(&kmalloced_params_lock);
  56
  57         return p->val;
  58 }
  59
  60 /* Does nothing if parameter wasn't kmalloced above. */
  61 static void maybe_kfree_parameter(void *param)
  62 {
  63         struct kmalloced_param *p;
  64
  65         spin_lock(&kmalloced_params_lock);
  66         list_for_each_entry(p, &kmalloced_params, list) {
  67                 if (p->val == param) {
  68                         list_del(&p->list);
  69                         kfree(p);
  70                         break;
  71                 }
  72         }
  73         spin_unlock(&kmalloced_params_lock);
  74 }
  75
  76 static char dash2underscore(char c)
  77 {
  78         if (c == '-')
  79                 return '_';
  80         return c;
  81 }
  82
  83 bool parameqn(const char *a, const char *b, size_t n)
  84 {
  85         size_t i;
  86
  87         for (i = 0; i < n; i++) {
  88                 if (dash2underscore(a[i]) != dash2underscore(b[i]))
  89                         return false;
  90         }
  91         return true;
  92 }
  93
  94 bool parameq(const char *a, const char *b)
  95 {
  96         return parameqn(a, b, strlen(a)+1);
  97 }
  98
  99 static void param_check_unsafe(const struct kernel_param *kp)
 100 {
 101         if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
 102                 pr_notice("Setting dangerous option %s - tainting kernel\n",
 103                           kp->name);
 104                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 105         }
 106 }
 107
 108 static int parse_one(char *param,
 109                      char *val,
 110                      const char *doing,
 111                      const struct kernel_param *params,
 112                      unsigned num_params,
 113                      s16 min_level,
 114                      s16 max_level,
 115                      void *arg,
 116                      int (*handle_unknown)(char *param, char *val,
 117                                      const char *doing, void *arg))
 118 {
 119         unsigned int i;
 120         int err;
 121
 122         /* Find parameter */
 123         for (i = 0; i < num_params; i++) {
 124                 if (parameq(param, params[i].name)) {
 125                         if (params[i].level < min_level
 126                             || params[i].level > max_level)
 127                                 return 0;
 128                         /* No one handled NULL, so do it here. */
 129                         if (!val &&
 130                             !(params[i].ops->flags & KERNEL_PARAM_OPS_FL_NOARG))
 131                                 return -EINVAL;
 132                         pr_debug("handling %s with %p\n", param,
 133                                 params[i].ops->set);
 134                         kernel_param_lock(params[i].mod);
 135                         param_check_unsafe(&params[i]);
 136                         err = params[i].ops->set(val, &params[i]);
 137                         kernel_param_unlock(params[i].mod);
 138                         return err;
 139                 }
 140         }
 141
 142         if (handle_unknown) {
 143                 pr_debug("doing %s: %s='%s'\n", doing, param, val);
 144                 return handle_unknown(param, val, doing, arg);
 145         }
 146
 147         pr_debug("Unknown argument '%s'\n", param);
 148         return -ENOENT;
 149 }
 150
 151 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
 152 char *parse_args(const char *doing,
 153                  char *args,
 154                  const struct kernel_param *params,
 155                  unsigned num,
 156                  s16 min_level,
 157                  s16 max_level,
 158                  void *arg,
 159                  int (*unknown)(char *param, char *val,
 160                                 const char *doing, void *arg))
 161 {
 162         char *param, *val, *err = NULL;
 163
 164         /* Chew leading spaces */
 165         args = skip_spaces(args);
 166
 167         if (*args)
 168                 pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);
 169
 170         while (*args) {
 171                 int ret;
 172                 int irq_was_disabled;
 173
 174                 args = next_arg(args, &param, &val);
 175                 /* Stop at -- */
 176                 if (!val && strcmp(param, "--") == 0)
 177                         return err ?: args;
 178                 irq_was_disabled = irqs_disabled();
 179                 ret = parse_one(param, val, doing, params, num,
 180                                 min_level, max_level, arg, unknown);
 181                 if (irq_was_disabled && !irqs_disabled())
 182                         pr_warn("%s: option '%s' enabled irq's!\n",
 183                                 doing, param);
 184
 185                 switch (ret) {
 186                 case 0:
 187                         continue;
 188                 case -ENOENT:
 189                         pr_err("%s: Unknown parameter `%s'\n", doing, param);
 190                         break;
 191                 case -ENOSPC:
 192                         pr_err("%s: `%s' too large for parameter `%s'\n",
 193                                doing, val ?: "", param);
 194                         break;
 195                 default:
 196                         pr_err("%s: `%s' invalid for parameter `%s'\n",
 197                                doing, val ?: "", param);
 198                         break;
 199                 }
 200
 201                 err = ERR_PTR(ret);
 202         }
 203
 204         return err;
 205 }
 206
 207 /* Lazy bastard, eh? */
 208 #define STANDARD_PARAM_DEF(name, type, format, strtolfn)                \
 209         int param_set_##name(const char *val, const struct kernel_param *kp) \
 210         {                                                               \
 211                 return strtolfn(val, 0, (type *)kp->arg);               \
 212         }                                                               \
 213         int param_get_##name(char *buffer, const struct kernel_param *kp) \
 214         {                                                               \
 215                 return scnprintf(buffer, PAGE_SIZE, format "\n",        \
 216                                 *((type *)kp->arg));                    \
 217         }                                                               \
 218         const struct kernel_param_ops param_ops_##name = {                      \
 219                 .set = param_set_##name,                                \
 220                 .get = param_get_##name,                                \
 221         };                                                              \
 222         EXPORT_SYMBOL(param_set_##name);                                \
 223         EXPORT_SYMBOL(param_get_##name);                                \
 224         EXPORT_SYMBOL(param_ops_##name)
 225
 226
 227 STANDARD_PARAM_DEF(byte,        unsigned char,          "%hhu", kstrtou8);
 228 STANDARD_PARAM_DEF(short,       short,                  "%hi",  kstrtos16);
 229 STANDARD_PARAM_DEF(ushort,      unsigned short,         "%hu",  kstrtou16);
 230 STANDARD_PARAM_DEF(int,         int,                    "%i",   kstrtoint);
 231 STANDARD_PARAM_DEF(uint,        unsigned int,           "%u",   kstrtouint);
 232 STANDARD_PARAM_DEF(long,        long,                   "%li",  kstrtol);
 233 STANDARD_PARAM_DEF(ulong,       unsigned long,          "%lu",  kstrtoul);
 234 STANDARD_PARAM_DEF(ullong,      unsigned long long,     "%llu", kstrtoull);
 235
 236 int param_set_charp(const char *val, const struct kernel_param *kp)
 237 {
 238         if (strlen(val) > 1024) {
 239                 pr_err("%s: string parameter too long\n", kp->name);
 240                 return -ENOSPC;
 241         }
 242
 243         maybe_kfree_parameter(*(char **)kp->arg);
 244
 245         /* This is a hack.  We can't kmalloc in early boot, and we
 246          * don't need to; this mangled commandline is preserved. */
 247         if (slab_is_available()) {
 248                 *(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
 249                 if (!*(char **)kp->arg)
 250                         return -ENOMEM;
 251                 strcpy(*(char **)kp->arg, val);
 252         } else
 253                 *(const char **)kp->arg = val;
 254
 255         return 0;
 256 }
 257 EXPORT_SYMBOL(param_set_charp);
 258
 259 int param_get_charp(char *buffer, const struct kernel_param *kp)
 260 {
 261         return scnprintf(buffer, PAGE_SIZE, "%s\n", *((char **)kp->arg));
 262 }
 263 EXPORT_SYMBOL(param_get_charp);
 264
 265 void param_free_charp(void *arg)
 266 {
 267         maybe_kfree_parameter(*((char **)arg));
 268 }
 269 EXPORT_SYMBOL(param_free_charp);
 270
 271 const struct kernel_param_ops param_ops_charp = {
 272         .set = param_set_charp,
 273         .get = param_get_charp,
 274         .free = param_free_charp,
 275 };
 276 EXPORT_SYMBOL(param_ops_charp);
 277
 278 /* Actually could be a bool or an int, for historical reasons. */
 279 int param_set_bool(const char *val, const struct kernel_param *kp)
 280 {
 281         /* No equals means "set"... */
 282         if (!val) val = "1";
 283
 284         /* One of =[yYnN01] */
 285         return strtobool(val, kp->arg);
 286 }
 287 EXPORT_SYMBOL(param_set_bool);
 288
 289 int param_get_bool(char *buffer, const struct kernel_param *kp)
 290 {
 291         /* Y and N chosen as being relatively non-coder friendly */
 292         return sprintf(buffer, "%c\n", *(bool *)kp->arg ? 'Y' : 'N');
 293 }
 294 EXPORT_SYMBOL(param_get_bool);
 295
 296 const struct kernel_param_ops param_ops_bool = {
 297         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 298         .set = param_set_bool,
 299         .get = param_get_bool,
 300 };
 301 EXPORT_SYMBOL(param_ops_bool);
 302
 303 int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
 304 {
 305         int err = 0;
 306         bool new_value;
 307         bool orig_value = *(bool *)kp->arg;
 308         struct kernel_param dummy_kp = *kp;
 309
 310         dummy_kp.arg = &new_value;
 311
 312         err = param_set_bool(val, &dummy_kp);
 313         if (err)
 314                 return err;
 315
 316         /* Don't let them unset it once it's set! */
 317         if (!new_value && orig_value)
 318                 return -EROFS;
 319
 320         if (new_value)
 321                 err = param_set_bool(val, kp);
 322
 323         return err;
 324 }
 325 EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
 326
 327 const struct kernel_param_ops param_ops_bool_enable_only = {
 328         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 329         .set = param_set_bool_enable_only,
 330         .get = param_get_bool,
 331 };
 332 EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
 333
 334 /* This one must be bool. */
 335 int param_set_invbool(const char *val, const struct kernel_param *kp)
 336 {
 337         int ret;
 338         bool boolval;
 339         struct kernel_param dummy;
 340
 341         dummy.arg = &boolval;
 342         ret = param_set_bool(val, &dummy);
 343         if (ret == 0)
 344                 *(bool *)kp->arg = !boolval;
 345         return ret;
 346 }
 347 EXPORT_SYMBOL(param_set_invbool);
 348
 349 int param_get_invbool(char *buffer, const struct kernel_param *kp)
 350 {
 351         return sprintf(buffer, "%c\n", (*(bool *)kp->arg) ? 'N' : 'Y');
 352 }
 353 EXPORT_SYMBOL(param_get_invbool);
 354
 355 const struct kernel_param_ops param_ops_invbool = {
 356         .set = param_set_invbool,
 357         .get = param_get_invbool,
 358 };
 359 EXPORT_SYMBOL(param_ops_invbool);
 360
 361 int param_set_bint(const char *val, const struct kernel_param *kp)
 362 {
 363         /* Match bool exactly, by re-using it. */
 364         struct kernel_param boolkp = *kp;
 365         bool v;
 366         int ret;
 367
 368         boolkp.arg = &v;
 369
 370         ret = param_set_bool(val, &boolkp);
 371         if (ret == 0)
 372                 *(int *)kp->arg = v;
 373         return ret;
 374 }
 375 EXPORT_SYMBOL(param_set_bint);
 376
 377 const struct kernel_param_ops param_ops_bint = {
 378         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 379         .set = param_set_bint,
 380         .get = param_get_int,
 381 };
 382 EXPORT_SYMBOL(param_ops_bint);
 383
 384 /* We break the rule and mangle the string. */
 385 static int param_array(struct module *mod,
 386                        const char *name,
 387                        const char *val,
 388                        unsigned int min, unsigned int max,
 389                        void *elem, int elemsize,
 390                        int (*set)(const char *, const struct kernel_param *kp),
 391                        s16 level,
 392                        unsigned int *num)
 393 {
 394         int ret;
 395         struct kernel_param kp;
 396         char save;
 397
 398         /* Get the name right for errors. */
 399         kp.name = name;
 400         kp.arg = elem;
 401         kp.level = level;
 402
 403         *num = 0;
 404         /* We expect a comma-separated list of values. */
 405         do {
 406                 int len;
 407
 408                 if (*num == max) {
 409                         pr_err("%s: can only take %i arguments\n", name, max);
 410                         return -EINVAL;
 411                 }
 412                 len = strcspn(val, ",");
 413
 414                 /* nul-terminate and parse */
 415                 save = val[len];
 416                 ((char *)val)[len] = '\0';
 417                 check_kparam_locked(mod);
 418                 ret = set(val, &kp);
 419
 420                 if (ret != 0)
 421                         return ret;
 422                 kp.arg += elemsize;
 423                 val += len+1;
 424                 (*num)++;
 425         } while (save == ',');
 426
 427         if (*num < min) {
 428                 pr_err("%s: needs at least %i arguments\n", name, min);
 429                 return -EINVAL;
 430         }
 431         return 0;
 432 }
 433
 434 static int param_array_set(const char *val, const struct kernel_param *kp)
 435 {
 436         const struct kparam_array *arr = kp->arr;
 437         unsigned int temp_num;
 438
 439         return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
 440                            arr->elemsize, arr->ops->set, kp->level,
 441                            arr->num ?: &temp_num);
 442 }
 443
 444 static int param_array_get(char *buffer, const struct kernel_param *kp)
 445 {
 446         int i, off, ret;
 447         const struct kparam_array *arr = kp->arr;
 448         struct kernel_param p = *kp;
 449
 450         for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
 451                 /* Replace \n with comma */
 452                 if (i)
 453                         buffer[off - 1] = ',';
 454                 p.arg = arr->elem + arr->elemsize * i;
 455                 check_kparam_locked(p.mod);
 456                 ret = arr->ops->get(buffer + off, &p);
 457                 if (ret < 0)
 458                         return ret;
 459                 off += ret;
 460         }
 461         buffer[off] = '\0';
 462         return off;
 463 }
 464
 465 static void param_array_free(void *arg)
 466 {
 467         unsigned int i;
 468         const struct kparam_array *arr = arg;
 469
 470         if (arr->ops->free)
 471                 for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
 472                         arr->ops->free(arr->elem + arr->elemsize * i);
 473 }
 474
 475 const struct kernel_param_ops param_array_ops = {
 476         .set = param_array_set,
 477         .get = param_array_get,
 478         .free = param_array_free,
 479 };
 480 EXPORT_SYMBOL(param_array_ops);
 481
 482 int param_set_copystring(const char *val, const struct kernel_param *kp)
 483 {
 484         const struct kparam_string *kps = kp->str;
 485
 486         if (strlen(val)+1 > kps->maxlen) {
 487                 pr_err("%s: string doesn't fit in %u chars.\n",
 488                        kp->name, kps->maxlen-1);
 489                 return -ENOSPC;
 490         }
 491         strcpy(kps->string, val);
 492         return 0;
 493 }
 494 EXPORT_SYMBOL(param_set_copystring);
 495
 496 int param_get_string(char *buffer, const struct kernel_param *kp)
 497 {
 498         const struct kparam_string *kps = kp->str;
 499         return scnprintf(buffer, PAGE_SIZE, "%s\n", kps->string);
 500 }
 501 EXPORT_SYMBOL(param_get_string);
 502
 503 const struct kernel_param_ops param_ops_string = {
 504         .set = param_set_copystring,
 505         .get = param_get_string,
 506 };
 507 EXPORT_SYMBOL(param_ops_string);
 508
 509 /* sysfs output in /sys/modules/XYZ/parameters/ */
 510 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
 511 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
 512
 513 struct param_attribute
 514 {
 515         struct module_attribute mattr;
 516         const struct kernel_param *param;
 517 };
 518
 519 struct module_param_attrs
 520 {
 521         unsigned int num;
 522         struct attribute_group grp;
 523         struct param_attribute attrs[0];
 524 };
 525
 526 #ifdef CONFIG_SYSFS
 527 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
 528
 529 static ssize_t param_attr_show(struct module_attribute *mattr,
 530                                struct module_kobject *mk, char *buf)
 531 {
 532         int count;
 533         struct param_attribute *attribute = to_param_attr(mattr);
 534
 535         if (!attribute->param->ops->get)
 536                 return -EPERM;
 537
 538         kernel_param_lock(mk->mod);
 539         count = attribute->param->ops->get(buf, attribute->param);
 540         kernel_param_unlock(mk->mod);
 541         return count;
 542 }
 543
 544 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 545 static ssize_t param_attr_store(struct module_attribute *mattr,
 546                                 struct module_kobject *mk,
 547                                 const char *buf, size_t len)
 548 {
 549         int err;
 550         struct param_attribute *attribute = to_param_attr(mattr);
 551
 552         if (!attribute->param->ops->set)
 553                 return -EPERM;
 554
 555         kernel_param_lock(mk->mod);
 556         param_check_unsafe(attribute->param);
 557         err = attribute->param->ops->set(buf, attribute->param);
 558         kernel_param_unlock(mk->mod);
 559         if (!err)
 560                 return len;
 561         return err;
 562 }
 563 #endif
 564
 565 #ifdef CONFIG_MODULES
 566 #define __modinit
 567 #else
 568 #define __modinit __init
 569 #endif
 570
 571 #ifdef CONFIG_SYSFS
 572 void kernel_param_lock(struct module *mod)
 573 {
 574         mutex_lock(KPARAM_MUTEX(mod));
 575 }
 576
 577 void kernel_param_unlock(struct module *mod)
 578 {
 579         mutex_unlock(KPARAM_MUTEX(mod));
 580 }
 581
 582 EXPORT_SYMBOL(kernel_param_lock);
 583 EXPORT_SYMBOL(kernel_param_unlock);
 584
 585 /*
 586  * add_sysfs_param - add a parameter to sysfs
 587  * @mk: struct module_kobject
 588  * @kp: the actual parameter definition to add to sysfs
 589  * @name: name of parameter
 590  *
 591  * Create a kobject if for a (per-module) parameter if mp NULL, and
 592  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
 593  * if there's an error.
 594  */
 595 static __modinit int add_sysfs_param(struct module_kobject *mk,
 596                                      const struct kernel_param *kp,
 597                                      const char *name)
 598 {
 599         struct module_param_attrs *new_mp;
 600         struct attribute **new_attrs;
 601         unsigned int i;
 602
 603         /* We don't bother calling this with invisible parameters. */
 604         BUG_ON(!kp->perm);
 605
 606         if (!mk->mp) {
 607                 /* First allocation. */
 608                 mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
 609                 if (!mk->mp)
 610                         return -ENOMEM;
 611                 mk->mp->grp.name = "parameters";
 612                 /* NULL-terminated attribute array. */
 613                 mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
 614                                             GFP_KERNEL);
 615                 /* Caller will cleanup via free_module_param_attrs */
 616                 if (!mk->mp->grp.attrs)
 617                         return -ENOMEM;
 618         }
 619
 620         /* Enlarge allocations. */
 621         new_mp = krealloc(mk->mp,
 622                           sizeof(*mk->mp) +
 623                           sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
 624                           GFP_KERNEL);
 625         if (!new_mp)
 626                 return -ENOMEM;
 627         mk->mp = new_mp;
 628
 629         /* Extra pointer for NULL terminator */
 630         new_attrs = krealloc(mk->mp->grp.attrs,
 631                              sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
 632                              GFP_KERNEL);
 633         if (!new_attrs)
 634                 return -ENOMEM;
 635         mk->mp->grp.attrs = new_attrs;
 636
 637         /* Tack new one on the end. */
 638         memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
 639         sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
 640         mk->mp->attrs[mk->mp->num].param = kp;
 641         mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
 642         /* Do not allow runtime DAC changes to make param writable. */
 643         if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
 644                 mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
 645         else
 646                 mk->mp->attrs[mk->mp->num].mattr.store = NULL;
 647         mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
 648         mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
 649         mk->mp->num++;
 650
 651         /* Fix up all the pointers, since krealloc can move us */
 652         for (i = 0; i < mk->mp->num; i++)
 653                 mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
 654         mk->mp->grp.attrs[mk->mp->num] = NULL;
 655         return 0;
 656 }
 657
 658 #ifdef CONFIG_MODULES
 659 static void free_module_param_attrs(struct module_kobject *mk)
 660 {
 661         if (mk->mp)
 662                 kfree(mk->mp->grp.attrs);
 663         kfree(mk->mp);
 664         mk->mp = NULL;
 665 }
 666
 667 /*
 668  * module_param_sysfs_setup - setup sysfs support for one module
 669  * @mod: module
 670  * @kparam: module parameters (array)
 671  * @num_params: number of module parameters
 672  *
 673  * Adds sysfs entries for module parameters under
 674  * /sys/module/[mod->name]/parameters/
 675  */
 676 int module_param_sysfs_setup(struct module *mod,
 677                              const struct kernel_param *kparam,
 678                              unsigned int num_params)
 679 {
 680         int i, err;
 681         bool params = false;
 682
 683         for (i = 0; i < num_params; i++) {
 684                 if (kparam[i].perm == 0)
 685                         continue;
 686                 err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
 687                 if (err) {
 688                         free_module_param_attrs(&mod->mkobj);
 689                         return err;
 690                 }
 691                 params = true;
 692         }
 693
 694         if (!params)
 695                 return 0;
 696
 697         /* Create the param group. */
 698         err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 699         if (err)
 700                 free_module_param_attrs(&mod->mkobj);
 701         return err;
 702 }
 703
 704 /*
 705  * module_param_sysfs_remove - remove sysfs support for one module
 706  * @mod: module
 707  *
 708  * Remove sysfs entries for module parameters and the corresponding
 709  * kobject.
 710  */
 711 void module_param_sysfs_remove(struct module *mod)
 712 {
 713         if (mod->mkobj.mp) {
 714                 sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 715                 /* We are positive that no one is using any param
 716                  * attrs at this point.  Deallocate immediately. */
 717                 free_module_param_attrs(&mod->mkobj);
 718         }
 719 }
 720 #endif
 721
 722 void destroy_params(const struct kernel_param *params, unsigned num)
 723 {
 724         unsigned int i;
 725
 726         for (i = 0; i < num; i++)
 727                 if (params[i].ops->free)
 728                         params[i].ops->free(params[i].arg);
 729 }
 730
 731 static struct module_kobject * __init locate_module_kobject(const char *name)
 732 {
 733         struct module_kobject *mk;
 734         struct kobject *kobj;
 735         int err;
 736
 737         kobj = kset_find_obj(module_kset, name);
 738         if (kobj) {
 739                 mk = to_module_kobject(kobj);
 740         } else {
 741                 mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
 742                 BUG_ON(!mk);
 743
 744                 mk->mod = THIS_MODULE;
 745                 mk->kobj.kset = module_kset;
 746                 err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
 747                                            "%s", name);
 748 #ifdef CONFIG_MODULES
 749                 if (!err)
 750                         err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
 751 #endif
 752                 if (err) {
 753                         kobject_put(&mk->kobj);
 754                         pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
 755                                 name, err);
 756                         return NULL;
 757                 }
 758
 759                 /* So that we hold reference in both cases. */
 760                 kobject_get(&mk->kobj);
 761         }
 762
 763         return mk;
 764 }
 765
 766 static void __init kernel_add_sysfs_param(const char *name,
 767                                           const struct kernel_param *kparam,
 768                                           unsigned int name_skip)
 769 {
 770         struct module_kobject *mk;
 771         int err;
 772
 773         mk = locate_module_kobject(name);
 774         if (!mk)
 775                 return;
 776
 777         /* We need to remove old parameters before adding more. */
 778         if (mk->mp)
 779                 sysfs_remove_group(&mk->kobj, &mk->mp->grp);
 780
 781         /* These should not fail at boot. */
 782         err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
 783         BUG_ON(err);
 784         err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
 785         BUG_ON(err);
 786         kobject_uevent(&mk->kobj, KOBJ_ADD);
 787         kobject_put(&mk->kobj);
 788 }
 789
 790 /*
 791  * param_sysfs_builtin - add sysfs parameters for built-in modules
 792  *
 793  * Add module_parameters to sysfs for "modules" built into the kernel.
 794  *
 795  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
 796  * "parameter" name is stored behind a dot in kernel_param->name. So,
 797  * extract the "module" name for all built-in kernel_param-eters,
 798  * and for all who have the same, call kernel_add_sysfs_param.
 799  */
 800 static void __init param_sysfs_builtin(void)
 801 {
 802         const struct kernel_param *kp;
 803         unsigned int name_len;
 804         char modname[MODULE_NAME_LEN];
 805
 806         for (kp = __start___param; kp < __stop___param; kp++) {
 807                 char *dot;
 808
 809                 if (kp->perm == 0)
 810                         continue;
 811
 812                 dot = strchr(kp->name, '.');
 813                 if (!dot) {
 814                         /* This happens for core_param() */
 815                         strcpy(modname, "kernel");
 816                         name_len = 0;
 817                 } else {
 818                         name_len = dot - kp->name + 1;
 819                         strlcpy(modname, kp->name, name_len);
 820                 }
 821                 kernel_add_sysfs_param(modname, kp, name_len);
 822         }
 823 }
 824
 825 ssize_t __modver_version_show(struct module_attribute *mattr,
 826                               struct module_kobject *mk, char *buf)
 827 {
 828         struct module_version_attribute *vattr =
 829                 container_of(mattr, struct module_version_attribute, mattr);
 830
 831         return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
 832 }
 833
 834 extern const struct module_version_attribute *__start___modver[];
 835 extern const struct module_version_attribute *__stop___modver[];
 836
 837 static void __init version_sysfs_builtin(void)
 838 {
 839         const struct module_version_attribute **p;
 840         struct module_kobject *mk;
 841         int err;
 842
 843         for (p = __start___modver; p < __stop___modver; p++) {
 844                 const struct module_version_attribute *vattr = *p;
 845
 846                 mk = locate_module_kobject(vattr->module_name);
 847                 if (mk) {
 848                         err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
 849                         WARN_ON_ONCE(err);
 850                         kobject_uevent(&mk->kobj, KOBJ_ADD);
 851                         kobject_put(&mk->kobj);
 852                 }
 853         }
 854 }
 855
 856 /* module-related sysfs stuff */
 857
 858 static ssize_t module_attr_show(struct kobject *kobj,
 859                                 struct attribute *attr,
 860                                 char *buf)
 861 {
 862         struct module_attribute *attribute;
 863         struct module_kobject *mk;
 864         int ret;
 865
 866         attribute = to_module_attr(attr);
 867         mk = to_module_kobject(kobj);
 868
 869         if (!attribute->show)
 870                 return -EIO;
 871
 872         ret = attribute->show(attribute, mk, buf);
 873
 874         return ret;
 875 }
 876
 877 static ssize_t module_attr_store(struct kobject *kobj,
 878                                 struct attribute *attr,
 879                                 const char *buf, size_t len)
 880 {
 881         struct module_attribute *attribute;
 882         struct module_kobject *mk;
 883         int ret;
 884
 885         attribute = to_module_attr(attr);
 886         mk = to_module_kobject(kobj);
 887
 888         if (!attribute->store)
 889                 return -EIO;
 890
 891         ret = attribute->store(attribute, mk, buf, len);
 892
 893         return ret;
 894 }
 895
 896 static const struct sysfs_ops module_sysfs_ops = {
 897         .show = module_attr_show,
 898         .store = module_attr_store,
 899 };
 900
 901 static int uevent_filter(struct kset *kset, struct kobject *kobj)
 902 {
 903         struct kobj_type *ktype = get_ktype(kobj);
 904
 905         if (ktype == &module_ktype)
 906                 return 1;
 907         return 0;
 908 }
 909
 910 static const struct kset_uevent_ops module_uevent_ops = {
 911         .filter = uevent_filter,
 912 };
 913
 914 struct kset *module_kset;
 915 int module_sysfs_initialized;
 916
 917 static void module_kobj_release(struct kobject *kobj)
 918 {
 919         struct module_kobject *mk = to_module_kobject(kobj);
 920         complete(mk->kobj_completion);
 921 }
 922
 923 struct kobj_type module_ktype = {
 924         .release   =    module_kobj_release,
 925         .sysfs_ops =    &module_sysfs_ops,
 926 };
 927
 928 /*
 929  * param_sysfs_init - wrapper for built-in params support
 930  */
 931 static int __init param_sysfs_init(void)
 932 {
 933         module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
 934         if (!module_kset) {
 935                 printk(KERN_WARNING "%s (%d): error creating kset\n",
 936                         __FILE__, __LINE__);
 937                 return -ENOMEM;
 938         }
 939         module_sysfs_initialized = 1;
 940
 941         version_sysfs_builtin();
 942         param_sysfs_builtin();
 943
 944         return 0;
 945 }
 946 subsys_initcall(param_sysfs_init);
 947
 948 #endif /* CONFIG_SYSFS */