root/kernel/params.c

DEFINITIONS

1. check_kparam_locked
2. check_kparam_locked
3. kmalloc_parameter
4. maybe_kfree_parameter
5. dash2underscore
6. parameqn
7. parameq
8. param_check_unsafe
9. parse_one
10. parse_args
11. param_set_charp
12. param_get_charp
13. param_free_charp
14. param_set_bool
15. param_get_bool
16. param_set_bool_enable_only
17. param_set_invbool
18. param_get_invbool
19. param_set_bint
20. param_array
21. param_array_set
22. param_array_get
23. param_array_free
24. param_set_copystring
25. param_get_string
26. param_attr_show
27. param_attr_store
28. kernel_param_lock
29. kernel_param_unlock
30. add_sysfs_param
31. free_module_param_attrs
32. module_param_sysfs_setup
33. module_param_sysfs_remove
34. destroy_params
35. locate_module_kobject
36. kernel_add_sysfs_param
37. param_sysfs_builtin
38. __modver_version_show
39. version_sysfs_builtin
40. module_attr_show
41. module_attr_store
42. uevent_filter
43. module_kobj_release
44. param_sysfs_init

   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 #include <linux/security.h>
  16 
  17 #ifdef CONFIG_SYSFS
  18 /* Protects all built-in parameters, modules use their own param_lock */
  19 static DEFINE_MUTEX(param_lock);
  20 
  21 /* Use the module's mutex, or if built-in use the built-in mutex */
  22 #ifdef CONFIG_MODULES
  23 #define KPARAM_MUTEX(mod)       ((mod) ? &(mod)->param_lock : &param_lock)
  24 #else
  25 #define KPARAM_MUTEX(mod)       (&param_lock)
  26 #endif
  27 
  28 static inline void check_kparam_locked(struct module *mod)
  29 {
  30         BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
  31 }
  32 #else
  33 static inline void check_kparam_locked(struct module *mod)
  34 {
  35 }
  36 #endif /* !CONFIG_SYSFS */
  37 
  38 /* This just allows us to keep track of which parameters are kmalloced. */
  39 struct kmalloced_param {
  40         struct list_head list;
  41         char val[];
  42 };
  43 static LIST_HEAD(kmalloced_params);
  44 static DEFINE_SPINLOCK(kmalloced_params_lock);
  45 
  46 static void *kmalloc_parameter(unsigned int size)
  47 {
  48         struct kmalloced_param *p;
  49 
  50         p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
  51         if (!p)
  52                 return NULL;
  53 
  54         spin_lock(&kmalloced_params_lock);
  55         list_add(&p->list, &kmalloced_params);
  56         spin_unlock(&kmalloced_params_lock);
  57 
  58         return p->val;
  59 }
  60 
  61 /* Does nothing if parameter wasn't kmalloced above. */
  62 static void maybe_kfree_parameter(void *param)
  63 {
  64         struct kmalloced_param *p;
  65 
  66         spin_lock(&kmalloced_params_lock);
  67         list_for_each_entry(p, &kmalloced_params, list) {
  68                 if (p->val == param) {
  69                         list_del(&p->list);
  70                         kfree(p);
  71                         break;
  72                 }
  73         }
  74         spin_unlock(&kmalloced_params_lock);
  75 }
  76 
  77 static char dash2underscore(char c)
  78 {
  79         if (c == '-')
  80                 return '_';
  81         return c;
  82 }
  83 
  84 bool parameqn(const char *a, const char *b, size_t n)
  85 {
  86         size_t i;
  87 
  88         for (i = 0; i < n; i++) {
  89                 if (dash2underscore(a[i]) != dash2underscore(b[i]))
  90                         return false;
  91         }
  92         return true;
  93 }
  94 
  95 bool parameq(const char *a, const char *b)
  96 {
  97         return parameqn(a, b, strlen(a)+1);
  98 }
  99 
 100 static bool param_check_unsafe(const struct kernel_param *kp)
 101 {
 102         if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
 103             security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
 104                 return false;
 105 
 106         if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
 107                 pr_notice("Setting dangerous option %s - tainting kernel\n",
 108                           kp->name);
 109                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 110         }
 111 
 112         return true;
 113 }
 114 
 115 static int parse_one(char *param,
 116                      char *val,
 117                      const char *doing,
 118                      const struct kernel_param *params,
 119                      unsigned num_params,
 120                      s16 min_level,
 121                      s16 max_level,
 122                      void *arg,
 123                      int (*handle_unknown)(char *param, char *val,
 124                                      const char *doing, void *arg))
 125 {
 126         unsigned int i;
 127         int err;
 128 
 129         /* Find parameter */
 130         for (i = 0; i < num_params; i++) {
 131                 if (parameq(param, params[i].name)) {
 132                         if (params[i].level < min_level
 133                             || params[i].level > max_level)
 134                                 return 0;
 135                         /* No one handled NULL, so do it here. */
 136                         if (!val &&
 137                             !(params[i].ops->flags & KERNEL_PARAM_OPS_FL_NOARG))
 138                                 return -EINVAL;
 139                         pr_debug("handling %s with %p\n", param,
 140                                 params[i].ops->set);
 141                         kernel_param_lock(params[i].mod);
 142                         if (param_check_unsafe(&params[i]))
 143                                 err = params[i].ops->set(val, &params[i]);
 144                         else
 145                                 err = -EPERM;
 146                         kernel_param_unlock(params[i].mod);
 147                         return err;
 148                 }
 149         }
 150 
 151         if (handle_unknown) {
 152                 pr_debug("doing %s: %s='%s'\n", doing, param, val);
 153                 return handle_unknown(param, val, doing, arg);
 154         }
 155 
 156         pr_debug("Unknown argument '%s'\n", param);
 157         return -ENOENT;
 158 }
 159 
 160 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
 161 char *parse_args(const char *doing,
 162                  char *args,
 163                  const struct kernel_param *params,
 164                  unsigned num,
 165                  s16 min_level,
 166                  s16 max_level,
 167                  void *arg,
 168                  int (*unknown)(char *param, char *val,
 169                                 const char *doing, void *arg))
 170 {
 171         char *param, *val, *err = NULL;
 172 
 173         /* Chew leading spaces */
 174         args = skip_spaces(args);
 175 
 176         if (*args)
 177                 pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);
 178 
 179         while (*args) {
 180                 int ret;
 181                 int irq_was_disabled;
 182 
 183                 args = next_arg(args, &param, &val);
 184                 /* Stop at -- */
 185                 if (!val && strcmp(param, "--") == 0)
 186                         return err ?: args;
 187                 irq_was_disabled = irqs_disabled();
 188                 ret = parse_one(param, val, doing, params, num,
 189                                 min_level, max_level, arg, unknown);
 190                 if (irq_was_disabled && !irqs_disabled())
 191                         pr_warn("%s: option '%s' enabled irq's!\n",
 192                                 doing, param);
 193 
 194                 switch (ret) {
 195                 case 0:
 196                         continue;
 197                 case -ENOENT:
 198                         pr_err("%s: Unknown parameter `%s'\n", doing, param);
 199                         break;
 200                 case -ENOSPC:
 201                         pr_err("%s: `%s' too large for parameter `%s'\n",
 202                                doing, val ?: "", param);
 203                         break;
 204                 default:
 205                         pr_err("%s: `%s' invalid for parameter `%s'\n",
 206                                doing, val ?: "", param);
 207                         break;
 208                 }
 209 
 210                 err = ERR_PTR(ret);
 211         }
 212 
 213         return err;
 214 }
 215 
 216 /* Lazy bastard, eh? */
 217 #define STANDARD_PARAM_DEF(name, type, format, strtolfn)                \
 218         int param_set_##name(const char *val, const struct kernel_param *kp) \
 219         {                                                               \
 220                 return strtolfn(val, 0, (type *)kp->arg);               \
 221         }                                                               \
 222         int param_get_##name(char *buffer, const struct kernel_param *kp) \
 223         {                                                               \
 224                 return scnprintf(buffer, PAGE_SIZE, format "\n",        \
 225                                 *((type *)kp->arg));                    \
 226         }                                                               \
 227         const struct kernel_param_ops param_ops_##name = {                      \
 228                 .set = param_set_##name,                                \
 229                 .get = param_get_##name,                                \
 230         };                                                              \
 231         EXPORT_SYMBOL(param_set_##name);                                \
 232         EXPORT_SYMBOL(param_get_##name);                                \
 233         EXPORT_SYMBOL(param_ops_##name)
 234 
 235 
 236 STANDARD_PARAM_DEF(byte,        unsigned char,          "%hhu", kstrtou8);
 237 STANDARD_PARAM_DEF(short,       short,                  "%hi",  kstrtos16);
 238 STANDARD_PARAM_DEF(ushort,      unsigned short,         "%hu",  kstrtou16);
 239 STANDARD_PARAM_DEF(int,         int,                    "%i",   kstrtoint);
 240 STANDARD_PARAM_DEF(uint,        unsigned int,           "%u",   kstrtouint);
 241 STANDARD_PARAM_DEF(long,        long,                   "%li",  kstrtol);
 242 STANDARD_PARAM_DEF(ulong,       unsigned long,          "%lu",  kstrtoul);
 243 STANDARD_PARAM_DEF(ullong,      unsigned long long,     "%llu", kstrtoull);
 244 
 245 int param_set_charp(const char *val, const struct kernel_param *kp)
 246 {
 247         if (strlen(val) > 1024) {
 248                 pr_err("%s: string parameter too long\n", kp->name);
 249                 return -ENOSPC;
 250         }
 251 
 252         maybe_kfree_parameter(*(char **)kp->arg);
 253 
 254         /* This is a hack.  We can't kmalloc in early boot, and we
 255          * don't need to; this mangled commandline is preserved. */
 256         if (slab_is_available()) {
 257                 *(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
 258                 if (!*(char **)kp->arg)
 259                         return -ENOMEM;
 260                 strcpy(*(char **)kp->arg, val);
 261         } else
 262                 *(const char **)kp->arg = val;
 263 
 264         return 0;
 265 }
 266 EXPORT_SYMBOL(param_set_charp);
 267 
 268 int param_get_charp(char *buffer, const struct kernel_param *kp)
 269 {
 270         return scnprintf(buffer, PAGE_SIZE, "%s\n", *((char **)kp->arg));
 271 }
 272 EXPORT_SYMBOL(param_get_charp);
 273 
 274 void param_free_charp(void *arg)
 275 {
 276         maybe_kfree_parameter(*((char **)arg));
 277 }
 278 EXPORT_SYMBOL(param_free_charp);
 279 
 280 const struct kernel_param_ops param_ops_charp = {
 281         .set = param_set_charp,
 282         .get = param_get_charp,
 283         .free = param_free_charp,
 284 };
 285 EXPORT_SYMBOL(param_ops_charp);
 286 
 287 /* Actually could be a bool or an int, for historical reasons. */
 288 int param_set_bool(const char *val, const struct kernel_param *kp)
 289 {
 290         /* No equals means "set"... */
 291         if (!val) val = "1";
 292 
 293         /* One of =[yYnN01] */
 294         return strtobool(val, kp->arg);
 295 }
 296 EXPORT_SYMBOL(param_set_bool);
 297 
 298 int param_get_bool(char *buffer, const struct kernel_param *kp)
 299 {
 300         /* Y and N chosen as being relatively non-coder friendly */
 301         return sprintf(buffer, "%c\n", *(bool *)kp->arg ? 'Y' : 'N');
 302 }
 303 EXPORT_SYMBOL(param_get_bool);
 304 
 305 const struct kernel_param_ops param_ops_bool = {
 306         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 307         .set = param_set_bool,
 308         .get = param_get_bool,
 309 };
 310 EXPORT_SYMBOL(param_ops_bool);
 311 
 312 int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
 313 {
 314         int err = 0;
 315         bool new_value;
 316         bool orig_value = *(bool *)kp->arg;
 317         struct kernel_param dummy_kp = *kp;
 318 
 319         dummy_kp.arg = &new_value;
 320 
 321         err = param_set_bool(val, &dummy_kp);
 322         if (err)
 323                 return err;
 324 
 325         /* Don't let them unset it once it's set! */
 326         if (!new_value && orig_value)
 327                 return -EROFS;
 328 
 329         if (new_value)
 330                 err = param_set_bool(val, kp);
 331 
 332         return err;
 333 }
 334 EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
 335 
 336 const struct kernel_param_ops param_ops_bool_enable_only = {
 337         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 338         .set = param_set_bool_enable_only,
 339         .get = param_get_bool,
 340 };
 341 EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
 342 
 343 /* This one must be bool. */
 344 int param_set_invbool(const char *val, const struct kernel_param *kp)
 345 {
 346         int ret;
 347         bool boolval;
 348         struct kernel_param dummy;
 349 
 350         dummy.arg = &boolval;
 351         ret = param_set_bool(val, &dummy);
 352         if (ret == 0)
 353                 *(bool *)kp->arg = !boolval;
 354         return ret;
 355 }
 356 EXPORT_SYMBOL(param_set_invbool);
 357 
 358 int param_get_invbool(char *buffer, const struct kernel_param *kp)
 359 {
 360         return sprintf(buffer, "%c\n", (*(bool *)kp->arg) ? 'N' : 'Y');
 361 }
 362 EXPORT_SYMBOL(param_get_invbool);
 363 
 364 const struct kernel_param_ops param_ops_invbool = {
 365         .set = param_set_invbool,
 366         .get = param_get_invbool,
 367 };
 368 EXPORT_SYMBOL(param_ops_invbool);
 369 
 370 int param_set_bint(const char *val, const struct kernel_param *kp)
 371 {
 372         /* Match bool exactly, by re-using it. */
 373         struct kernel_param boolkp = *kp;
 374         bool v;
 375         int ret;
 376 
 377         boolkp.arg = &v;
 378 
 379         ret = param_set_bool(val, &boolkp);
 380         if (ret == 0)
 381                 *(int *)kp->arg = v;
 382         return ret;
 383 }
 384 EXPORT_SYMBOL(param_set_bint);
 385 
 386 const struct kernel_param_ops param_ops_bint = {
 387         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 388         .set = param_set_bint,
 389         .get = param_get_int,
 390 };
 391 EXPORT_SYMBOL(param_ops_bint);
 392 
 393 /* We break the rule and mangle the string. */
 394 static int param_array(struct module *mod,
 395                        const char *name,
 396                        const char *val,
 397                        unsigned int min, unsigned int max,
 398                        void *elem, int elemsize,
 399                        int (*set)(const char *, const struct kernel_param *kp),
 400                        s16 level,
 401                        unsigned int *num)
 402 {
 403         int ret;
 404         struct kernel_param kp;
 405         char save;
 406 
 407         /* Get the name right for errors. */
 408         kp.name = name;
 409         kp.arg = elem;
 410         kp.level = level;
 411 
 412         *num = 0;
 413         /* We expect a comma-separated list of values. */
 414         do {
 415                 int len;
 416 
 417                 if (*num == max) {
 418                         pr_err("%s: can only take %i arguments\n", name, max);
 419                         return -EINVAL;
 420                 }
 421                 len = strcspn(val, ",");
 422 
 423                 /* nul-terminate and parse */
 424                 save = val[len];
 425                 ((char *)val)[len] = '\0';
 426                 check_kparam_locked(mod);
 427                 ret = set(val, &kp);
 428 
 429                 if (ret != 0)
 430                         return ret;
 431                 kp.arg += elemsize;
 432                 val += len+1;
 433                 (*num)++;
 434         } while (save == ',');
 435 
 436         if (*num < min) {
 437                 pr_err("%s: needs at least %i arguments\n", name, min);
 438                 return -EINVAL;
 439         }
 440         return 0;
 441 }
 442 
 443 static int param_array_set(const char *val, const struct kernel_param *kp)
 444 {
 445         const struct kparam_array *arr = kp->arr;
 446         unsigned int temp_num;
 447 
 448         return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
 449                            arr->elemsize, arr->ops->set, kp->level,
 450                            arr->num ?: &temp_num);
 451 }
 452 
 453 static int param_array_get(char *buffer, const struct kernel_param *kp)
 454 {
 455         int i, off, ret;
 456         const struct kparam_array *arr = kp->arr;
 457         struct kernel_param p = *kp;
 458 
 459         for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
 460                 /* Replace \n with comma */
 461                 if (i)
 462                         buffer[off - 1] = ',';
 463                 p.arg = arr->elem + arr->elemsize * i;
 464                 check_kparam_locked(p.mod);
 465                 ret = arr->ops->get(buffer + off, &p);
 466                 if (ret < 0)
 467                         return ret;
 468                 off += ret;
 469         }
 470         buffer[off] = '\0';
 471         return off;
 472 }
 473 
 474 static void param_array_free(void *arg)
 475 {
 476         unsigned int i;
 477         const struct kparam_array *arr = arg;
 478 
 479         if (arr->ops->free)
 480                 for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
 481                         arr->ops->free(arr->elem + arr->elemsize * i);
 482 }
 483 
 484 const struct kernel_param_ops param_array_ops = {
 485         .set = param_array_set,
 486         .get = param_array_get,
 487         .free = param_array_free,
 488 };
 489 EXPORT_SYMBOL(param_array_ops);
 490 
 491 int param_set_copystring(const char *val, const struct kernel_param *kp)
 492 {
 493         const struct kparam_string *kps = kp->str;
 494 
 495         if (strlen(val)+1 > kps->maxlen) {
 496                 pr_err("%s: string doesn't fit in %u chars.\n",
 497                        kp->name, kps->maxlen-1);
 498                 return -ENOSPC;
 499         }
 500         strcpy(kps->string, val);
 501         return 0;
 502 }
 503 EXPORT_SYMBOL(param_set_copystring);
 504 
 505 int param_get_string(char *buffer, const struct kernel_param *kp)
 506 {
 507         const struct kparam_string *kps = kp->str;
 508         return scnprintf(buffer, PAGE_SIZE, "%s\n", kps->string);
 509 }
 510 EXPORT_SYMBOL(param_get_string);
 511 
 512 const struct kernel_param_ops param_ops_string = {
 513         .set = param_set_copystring,
 514         .get = param_get_string,
 515 };
 516 EXPORT_SYMBOL(param_ops_string);
 517 
 518 /* sysfs output in /sys/modules/XYZ/parameters/ */
 519 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
 520 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
 521 
 522 struct param_attribute
 523 {
 524         struct module_attribute mattr;
 525         const struct kernel_param *param;
 526 };
 527 
 528 struct module_param_attrs
 529 {
 530         unsigned int num;
 531         struct attribute_group grp;
 532         struct param_attribute attrs[0];
 533 };
 534 
 535 #ifdef CONFIG_SYSFS
 536 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
 537 
 538 static ssize_t param_attr_show(struct module_attribute *mattr,
 539                                struct module_kobject *mk, char *buf)
 540 {
 541         int count;
 542         struct param_attribute *attribute = to_param_attr(mattr);
 543 
 544         if (!attribute->param->ops->get)
 545                 return -EPERM;
 546 
 547         kernel_param_lock(mk->mod);
 548         count = attribute->param->ops->get(buf, attribute->param);
 549         kernel_param_unlock(mk->mod);
 550         return count;
 551 }
 552 
 553 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 554 static ssize_t param_attr_store(struct module_attribute *mattr,
 555                                 struct module_kobject *mk,
 556                                 const char *buf, size_t len)
 557 {
 558         int err;
 559         struct param_attribute *attribute = to_param_attr(mattr);
 560 
 561         if (!attribute->param->ops->set)
 562                 return -EPERM;
 563 
 564         kernel_param_lock(mk->mod);
 565         if (param_check_unsafe(attribute->param))
 566                 err = attribute->param->ops->set(buf, attribute->param);
 567         else
 568                 err = -EPERM;
 569         kernel_param_unlock(mk->mod);
 570         if (!err)
 571                 return len;
 572         return err;
 573 }
 574 #endif
 575 
 576 #ifdef CONFIG_MODULES
 577 #define __modinit
 578 #else
 579 #define __modinit __init
 580 #endif
 581 
 582 #ifdef CONFIG_SYSFS
 583 void kernel_param_lock(struct module *mod)
 584 {
 585         mutex_lock(KPARAM_MUTEX(mod));
 586 }
 587 
 588 void kernel_param_unlock(struct module *mod)
 589 {
 590         mutex_unlock(KPARAM_MUTEX(mod));
 591 }
 592 
 593 EXPORT_SYMBOL(kernel_param_lock);
 594 EXPORT_SYMBOL(kernel_param_unlock);
 595 
 596 /*
 597  * add_sysfs_param - add a parameter to sysfs
 598  * @mk: struct module_kobject
 599  * @kp: the actual parameter definition to add to sysfs
 600  * @name: name of parameter
 601  *
 602  * Create a kobject if for a (per-module) parameter if mp NULL, and
 603  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
 604  * if there's an error.
 605  */
 606 static __modinit int add_sysfs_param(struct module_kobject *mk,
 607                                      const struct kernel_param *kp,
 608                                      const char *name)
 609 {
 610         struct module_param_attrs *new_mp;
 611         struct attribute **new_attrs;
 612         unsigned int i;
 613 
 614         /* We don't bother calling this with invisible parameters. */
 615         BUG_ON(!kp->perm);
 616 
 617         if (!mk->mp) {
 618                 /* First allocation. */
 619                 mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
 620                 if (!mk->mp)
 621                         return -ENOMEM;
 622                 mk->mp->grp.name = "parameters";
 623                 /* NULL-terminated attribute array. */
 624                 mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
 625                                             GFP_KERNEL);
 626                 /* Caller will cleanup via free_module_param_attrs */
 627                 if (!mk->mp->grp.attrs)
 628                         return -ENOMEM;
 629         }
 630 
 631         /* Enlarge allocations. */
 632         new_mp = krealloc(mk->mp,
 633                           sizeof(*mk->mp) +
 634                           sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
 635                           GFP_KERNEL);
 636         if (!new_mp)
 637                 return -ENOMEM;
 638         mk->mp = new_mp;
 639 
 640         /* Extra pointer for NULL terminator */
 641         new_attrs = krealloc(mk->mp->grp.attrs,
 642                              sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
 643                              GFP_KERNEL);
 644         if (!new_attrs)
 645                 return -ENOMEM;
 646         mk->mp->grp.attrs = new_attrs;
 647 
 648         /* Tack new one on the end. */
 649         memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
 650         sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
 651         mk->mp->attrs[mk->mp->num].param = kp;
 652         mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
 653         /* Do not allow runtime DAC changes to make param writable. */
 654         if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
 655                 mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
 656         else
 657                 mk->mp->attrs[mk->mp->num].mattr.store = NULL;
 658         mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
 659         mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
 660         mk->mp->num++;
 661 
 662         /* Fix up all the pointers, since krealloc can move us */
 663         for (i = 0; i < mk->mp->num; i++)
 664                 mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
 665         mk->mp->grp.attrs[mk->mp->num] = NULL;
 666         return 0;
 667 }
 668 
 669 #ifdef CONFIG_MODULES
 670 static void free_module_param_attrs(struct module_kobject *mk)
 671 {
 672         if (mk->mp)
 673                 kfree(mk->mp->grp.attrs);
 674         kfree(mk->mp);
 675         mk->mp = NULL;
 676 }
 677 
 678 /*
 679  * module_param_sysfs_setup - setup sysfs support for one module
 680  * @mod: module
 681  * @kparam: module parameters (array)
 682  * @num_params: number of module parameters
 683  *
 684  * Adds sysfs entries for module parameters under
 685  * /sys/module/[mod->name]/parameters/
 686  */
 687 int module_param_sysfs_setup(struct module *mod,
 688                              const struct kernel_param *kparam,
 689                              unsigned int num_params)
 690 {
 691         int i, err;
 692         bool params = false;
 693 
 694         for (i = 0; i < num_params; i++) {
 695                 if (kparam[i].perm == 0)
 696                         continue;
 697                 err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
 698                 if (err) {
 699                         free_module_param_attrs(&mod->mkobj);
 700                         return err;
 701                 }
 702                 params = true;
 703         }
 704 
 705         if (!params)
 706                 return 0;
 707 
 708         /* Create the param group. */
 709         err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 710         if (err)
 711                 free_module_param_attrs(&mod->mkobj);
 712         return err;
 713 }
 714 
 715 /*
 716  * module_param_sysfs_remove - remove sysfs support for one module
 717  * @mod: module
 718  *
 719  * Remove sysfs entries for module parameters and the corresponding
 720  * kobject.
 721  */
 722 void module_param_sysfs_remove(struct module *mod)
 723 {
 724         if (mod->mkobj.mp) {
 725                 sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 726                 /* We are positive that no one is using any param
 727                  * attrs at this point.  Deallocate immediately. */
 728                 free_module_param_attrs(&mod->mkobj);
 729         }
 730 }
 731 #endif
 732 
 733 void destroy_params(const struct kernel_param *params, unsigned num)
 734 {
 735         unsigned int i;
 736 
 737         for (i = 0; i < num; i++)
 738                 if (params[i].ops->free)
 739                         params[i].ops->free(params[i].arg);
 740 }
 741 
 742 static struct module_kobject * __init locate_module_kobject(const char *name)
 743 {
 744         struct module_kobject *mk;
 745         struct kobject *kobj;
 746         int err;
 747 
 748         kobj = kset_find_obj(module_kset, name);
 749         if (kobj) {
 750                 mk = to_module_kobject(kobj);
 751         } else {
 752                 mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
 753                 BUG_ON(!mk);
 754 
 755                 mk->mod = THIS_MODULE;
 756                 mk->kobj.kset = module_kset;
 757                 err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
 758                                            "%s", name);
 759 #ifdef CONFIG_MODULES
 760                 if (!err)
 761                         err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
 762 #endif
 763                 if (err) {
 764                         kobject_put(&mk->kobj);
 765                         pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
 766                                 name, err);
 767                         return NULL;
 768                 }
 769 
 770                 /* So that we hold reference in both cases. */
 771                 kobject_get(&mk->kobj);
 772         }
 773 
 774         return mk;
 775 }
 776 
 777 static void __init kernel_add_sysfs_param(const char *name,
 778                                           const struct kernel_param *kparam,
 779                                           unsigned int name_skip)
 780 {
 781         struct module_kobject *mk;
 782         int err;
 783 
 784         mk = locate_module_kobject(name);
 785         if (!mk)
 786                 return;
 787 
 788         /* We need to remove old parameters before adding more. */
 789         if (mk->mp)
 790                 sysfs_remove_group(&mk->kobj, &mk->mp->grp);
 791 
 792         /* These should not fail at boot. */
 793         err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
 794         BUG_ON(err);
 795         err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
 796         BUG_ON(err);
 797         kobject_uevent(&mk->kobj, KOBJ_ADD);
 798         kobject_put(&mk->kobj);
 799 }
 800 
 801 /*
 802  * param_sysfs_builtin - add sysfs parameters for built-in modules
 803  *
 804  * Add module_parameters to sysfs for "modules" built into the kernel.
 805  *
 806  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
 807  * "parameter" name is stored behind a dot in kernel_param->name. So,
 808  * extract the "module" name for all built-in kernel_param-eters,
 809  * and for all who have the same, call kernel_add_sysfs_param.
 810  */
 811 static void __init param_sysfs_builtin(void)
 812 {
 813         const struct kernel_param *kp;
 814         unsigned int name_len;
 815         char modname[MODULE_NAME_LEN];
 816 
 817         for (kp = __start___param; kp < __stop___param; kp++) {
 818                 char *dot;
 819 
 820                 if (kp->perm == 0)
 821                         continue;
 822 
 823                 dot = strchr(kp->name, '.');
 824                 if (!dot) {
 825                         /* This happens for core_param() */
 826                         strcpy(modname, "kernel");
 827                         name_len = 0;
 828                 } else {
 829                         name_len = dot - kp->name + 1;
 830                         strlcpy(modname, kp->name, name_len);
 831                 }
 832                 kernel_add_sysfs_param(modname, kp, name_len);
 833         }
 834 }
 835 
 836 ssize_t __modver_version_show(struct module_attribute *mattr,
 837                               struct module_kobject *mk, char *buf)
 838 {
 839         struct module_version_attribute *vattr =
 840                 container_of(mattr, struct module_version_attribute, mattr);
 841 
 842         return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
 843 }
 844 
 845 extern const struct module_version_attribute *__start___modver[];
 846 extern const struct module_version_attribute *__stop___modver[];
 847 
 848 static void __init version_sysfs_builtin(void)
 849 {
 850         const struct module_version_attribute **p;
 851         struct module_kobject *mk;
 852         int err;
 853 
 854         for (p = __start___modver; p < __stop___modver; p++) {
 855                 const struct module_version_attribute *vattr = *p;
 856 
 857                 mk = locate_module_kobject(vattr->module_name);
 858                 if (mk) {
 859                         err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
 860                         WARN_ON_ONCE(err);
 861                         kobject_uevent(&mk->kobj, KOBJ_ADD);
 862                         kobject_put(&mk->kobj);
 863                 }
 864         }
 865 }
 866 
 867 /* module-related sysfs stuff */
 868 
 869 static ssize_t module_attr_show(struct kobject *kobj,
 870                                 struct attribute *attr,
 871                                 char *buf)
 872 {
 873         struct module_attribute *attribute;
 874         struct module_kobject *mk;
 875         int ret;
 876 
 877         attribute = to_module_attr(attr);
 878         mk = to_module_kobject(kobj);
 879 
 880         if (!attribute->show)
 881                 return -EIO;
 882 
 883         ret = attribute->show(attribute, mk, buf);
 884 
 885         return ret;
 886 }
 887 
 888 static ssize_t module_attr_store(struct kobject *kobj,
 889                                 struct attribute *attr,
 890                                 const char *buf, size_t len)
 891 {
 892         struct module_attribute *attribute;
 893         struct module_kobject *mk;
 894         int ret;
 895 
 896         attribute = to_module_attr(attr);
 897         mk = to_module_kobject(kobj);
 898 
 899         if (!attribute->store)
 900                 return -EIO;
 901 
 902         ret = attribute->store(attribute, mk, buf, len);
 903 
 904         return ret;
 905 }
 906 
 907 static const struct sysfs_ops module_sysfs_ops = {
 908         .show = module_attr_show,
 909         .store = module_attr_store,
 910 };
 911 
 912 static int uevent_filter(struct kset *kset, struct kobject *kobj)
 913 {
 914         struct kobj_type *ktype = get_ktype(kobj);
 915 
 916         if (ktype == &module_ktype)
 917                 return 1;
 918         return 0;
 919 }
 920 
 921 static const struct kset_uevent_ops module_uevent_ops = {
 922         .filter = uevent_filter,
 923 };
 924 
 925 struct kset *module_kset;
 926 int module_sysfs_initialized;
 927 
 928 static void module_kobj_release(struct kobject *kobj)
 929 {
 930         struct module_kobject *mk = to_module_kobject(kobj);
 931         complete(mk->kobj_completion);
 932 }
 933 
 934 struct kobj_type module_ktype = {
 935         .release   =    module_kobj_release,
 936         .sysfs_ops =    &module_sysfs_ops,
 937 };
 938 
 939 /*
 940  * param_sysfs_init - wrapper for built-in params support
 941  */
 942 static int __init param_sysfs_init(void)
 943 {
 944         module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
 945         if (!module_kset) {
 946                 printk(KERN_WARNING "%s (%d): error creating kset\n",
 947                         __FILE__, __LINE__);
 948                 return -ENOMEM;
 949         }
 950         module_sysfs_initialized = 1;
 951 
 952         version_sysfs_builtin();
 953         param_sysfs_builtin();
 954 
 955         return 0;
 956 }
 957 subsys_initcall(param_sysfs_init);
 958 
 959 #endif /* CONFIG_SYSFS */