include/linux/moduleparam.h

   1 #ifndef _LINUX_MODULE_PARAMS_H
   2 #define _LINUX_MODULE_PARAMS_H
   3 /* (C) Copyright 2001, 2002 Rusty Russell IBM Corporation */
   4 #include <linux/init.h>
   5 #include <linux/stringify.h>
   6 #include <linux/kernel.h>
   7
   8 /* You can override this manually, but generally this should match the
   9    module name. */
  10 #ifdef MODULE
  11 #define MODULE_PARAM_PREFIX /* empty */
  12 #else
  13 #define MODULE_PARAM_PREFIX KBUILD_MODNAME "."
  14 #endif
  15
  16 /* Chosen so that structs with an unsigned long line up. */
  17 #define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
  18
  19 #ifdef MODULE
  20 #define __MODULE_INFO(tag, name, info)                                    \
  21 static const char __UNIQUE_ID(name)[]                                     \
  22   __used __attribute__((section(".modinfo"), unused, aligned(1)))         \
  23   = __stringify(tag) "=" info
  24 #else  /* !MODULE */
  25 /* This struct is here for syntactic coherency, it is not used */
  26 #define __MODULE_INFO(tag, name, info)                                    \
  27   struct __UNIQUE_ID(name) {}
  28 #endif
  29 #define __MODULE_PARM_TYPE(name, _type)                                   \
  30   __MODULE_INFO(parmtype, name##type, #name ":" _type)
  31
  32 /* One for each parameter, describing how to use it.  Some files do
  33    multiple of these per line, so can't just use MODULE_INFO. */
  34 #define MODULE_PARM_DESC(_parm, desc) \
  35         __MODULE_INFO(parm, _parm, #_parm ":" desc)
  36
  37 struct kernel_param;
  38
  39 struct kernel_param_ops {
  40         /* Returns 0, or -errno.  arg is in kp->arg. */
  41         int (*set)(const char *val, const struct kernel_param *kp);
  42         /* Returns length written or -errno.  Buffer is 4k (ie. be short!) */
  43         int (*get)(char *buffer, const struct kernel_param *kp);
  44         /* Optional function to free kp->arg when module unloaded. */
  45         void (*free)(void *arg);
  46 };
  47
  48 struct kernel_param {
  49         const char *name;
  50         const struct kernel_param_ops *ops;
  51         u16 perm;
  52         s16 level;
  53         union {
  54                 void *arg;
  55                 const struct kparam_string *str;
  56                 const struct kparam_array *arr;
  57         };
  58 };
  59
  60 /* Special one for strings we want to copy into */
  61 struct kparam_string {
  62         unsigned int maxlen;
  63         char *string;
  64 };
  65
  66 /* Special one for arrays */
  67 struct kparam_array
  68 {
  69         unsigned int max;
  70         unsigned int elemsize;
  71         unsigned int *num;
  72         const struct kernel_param_ops *ops;
  73         void *elem;
  74 };
  75
  76 /**
  77  * module_param - typesafe helper for a module/cmdline parameter
  78  * @value: the variable to alter, and exposed parameter name.
  79  * @type: the type of the parameter
  80  * @perm: visibility in sysfs.
  81  *
  82  * @value becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
  83  * ".") the kernel commandline parameter.  Note that - is changed to _, so
  84  * the user can use "foo-bar=1" even for variable "foo_bar".
  85  *
  86  * @perm is 0 if the the variable is not to appear in sysfs, or 0444
  87  * for world-readable, 0644 for root-writable, etc.  Note that if it
  88  * is writable, you may need to use kparam_block_sysfs_write() around
  89  * accesses (esp. charp, which can be kfreed when it changes).
  90  *
  91  * The @type is simply pasted to refer to a param_ops_##type and a
  92  * param_check_##type: for convenience many standard types are provided but
  93  * you can create your own by defining those variables.
  94  *
  95  * Standard types are:
  96  *      byte, short, ushort, int, uint, long, ulong
  97  *      charp: a character pointer
  98  *      bool: a bool, values 0/1, y/n, Y/N.
  99  *      invbool: the above, only sense-reversed (N = true).
 100  */
 101 #define module_param(name, type, perm)                          \
 102         module_param_named(name, name, type, perm)
 103
 104 /**
 105  * module_param_named - typesafe helper for a renamed module/cmdline parameter
 106  * @name: a valid C identifier which is the parameter name.
 107  * @value: the actual lvalue to alter.
 108  * @type: the type of the parameter
 109  * @perm: visibility in sysfs.
 110  *
 111  * Usually it's a good idea to have variable names and user-exposed names the
 112  * same, but that's harder if the variable must be non-static or is inside a
 113  * structure.  This allows exposure under a different name.
 114  */
 115 #define module_param_named(name, value, type, perm)                        \
 116         param_check_##type(name, &(value));                                \
 117         module_param_cb(name, &param_ops_##type, &value, perm);            \
 118         __MODULE_PARM_TYPE(name, #type)
 119
 120 /**
 121  * module_param_cb - general callback for a module/cmdline parameter
 122  * @name: a valid C identifier which is the parameter name.
 123  * @ops: the set & get operations for this parameter.
 124  * @perm: visibility in sysfs.
 125  *
 126  * The ops can have NULL set or get functions.
 127  */
 128 #define module_param_cb(name, ops, arg, perm)                                 \
 129         __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1)
 130
 131 /**
 132  * <level>_param_cb - general callback for a module/cmdline parameter
 133  *                    to be evaluated before certain initcall level
 134  * @name: a valid C identifier which is the parameter name.
 135  * @ops: the set & get operations for this parameter.
 136  * @perm: visibility in sysfs.
 137  *
 138  * The ops can have NULL set or get functions.
 139  */
 140 #define __level_param_cb(name, ops, arg, perm, level)                   \
 141         __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, level)
 142
 143 #define core_param_cb(name, ops, arg, perm)             \
 144         __level_param_cb(name, ops, arg, perm, 1)
 145
 146 #define postcore_param_cb(name, ops, arg, perm)         \
 147         __level_param_cb(name, ops, arg, perm, 2)
 148
 149 #define arch_param_cb(name, ops, arg, perm)             \
 150         __level_param_cb(name, ops, arg, perm, 3)
 151
 152 #define subsys_param_cb(name, ops, arg, perm)           \
 153         __level_param_cb(name, ops, arg, perm, 4)
 154
 155 #define fs_param_cb(name, ops, arg, perm)               \
 156         __level_param_cb(name, ops, arg, perm, 5)
 157
 158 #define device_param_cb(name, ops, arg, perm)           \
 159         __level_param_cb(name, ops, arg, perm, 6)
 160
 161 #define late_param_cb(name, ops, arg, perm)             \
 162         __level_param_cb(name, ops, arg, perm, 7)
 163
 164 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
 165    read-only sections (which is part of respective UNIX ABI on these
 166    platforms). So 'const' makes no sense and even causes compile failures
 167    with some compilers. */
 168 #if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
 169 #define __moduleparam_const
 170 #else
 171 #define __moduleparam_const const
 172 #endif
 173
 174 /* This is the fundamental function for registering boot/module
 175    parameters. */
 176 #define __module_param_call(prefix, name, ops, arg, perm, level)        \
 177         /* Default value instead of permissions? */                     \
 178         static int __param_perm_check_##name __attribute__((unused)) =  \
 179         BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
 180         + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
 181         static const char __param_str_##name[] = prefix #name;          \
 182         static struct kernel_param __moduleparam_const __param_##name   \
 183         __used                                                          \
 184     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
 185         = { __param_str_##name, ops, perm, level, { arg } }
 186
 187 /* Obsolete - use module_param_cb() */
 188 #define module_param_call(name, set, get, arg, perm)                    \
 189         static struct kernel_param_ops __param_ops_##name =             \
 190                  { (void *)set, (void *)get };                          \
 191         __module_param_call(MODULE_PARAM_PREFIX,                        \
 192                             name, &__param_ops_##name, arg,             \
 193                             (perm) + sizeof(__check_old_set_param(set))*0, -1)
 194
 195 /* We don't get oldget: it's often a new-style param_get_uint, etc. */
 196 static inline int
 197 __check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 198 {
 199         return 0;
 200 }
 201
 202 /**
 203  * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
 204  * @name: the name of the parameter
 205  *
 206  * There's no point blocking write on a paramter that isn't writable via sysfs!
 207  */
 208 #define kparam_block_sysfs_write(name)                  \
 209         do {                                            \
 210                 BUG_ON(!(__param_##name.perm & 0222));  \
 211                 __kernel_param_lock();                  \
 212         } while (0)
 213
 214 /**
 215  * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
 216  * @name: the name of the parameter
 217  */
 218 #define kparam_unblock_sysfs_write(name)                \
 219         do {                                            \
 220                 BUG_ON(!(__param_##name.perm & 0222));  \
 221                 __kernel_param_unlock();                \
 222         } while (0)
 223
 224 /**
 225  * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
 226  * @name: the name of the parameter
 227  *
 228  * This also blocks sysfs writes.
 229  */
 230 #define kparam_block_sysfs_read(name)                   \
 231         do {                                            \
 232                 BUG_ON(!(__param_##name.perm & 0444));  \
 233                 __kernel_param_lock();                  \
 234         } while (0)
 235
 236 /**
 237  * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
 238  * @name: the name of the parameter
 239  */
 240 #define kparam_unblock_sysfs_read(name)                 \
 241         do {                                            \
 242                 BUG_ON(!(__param_##name.perm & 0444));  \
 243                 __kernel_param_unlock();                \
 244         } while (0)
 245
 246 #ifdef CONFIG_SYSFS
 247 extern void __kernel_param_lock(void);
 248 extern void __kernel_param_unlock(void);
 249 #else
 250 static inline void __kernel_param_lock(void)
 251 {
 252 }
 253 static inline void __kernel_param_unlock(void)
 254 {
 255 }
 256 #endif
 257
 258 #ifndef MODULE
 259 /**
 260  * core_param - define a historical core kernel parameter.
 261  * @name: the name of the cmdline and sysfs parameter (often the same as var)
 262  * @var: the variable
 263  * @type: the type of the parameter
 264  * @perm: visibility in sysfs
 265  *
 266  * core_param is just like module_param(), but cannot be modular and
 267  * doesn't add a prefix (such as "printk.").  This is for compatibility
 268  * with __setup(), and it makes sense as truly core parameters aren't
 269  * tied to the particular file they're in.
 270  */
 271 #define core_param(name, var, type, perm)                               \
 272         param_check_##type(name, &(var));                               \
 273         __module_param_call("", name, &param_ops_##type, &var, perm, -1)
 274 #endif /* !MODULE */
 275
 276 /**
 277  * module_param_string - a char array parameter
 278  * @name: the name of the parameter
 279  * @string: the string variable
 280  * @len: the maximum length of the string, incl. terminator
 281  * @perm: visibility in sysfs.
 282  *
 283  * This actually copies the string when it's set (unlike type charp).
 284  * @len is usually just sizeof(string).
 285  */
 286 #define module_param_string(name, string, len, perm)                    \
 287         static const struct kparam_string __param_string_##name         \
 288                 = { len, string };                                      \
 289         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 290                             &param_ops_string,                          \
 291                             .str = &__param_string_##name, perm, -1);   \
 292         __MODULE_PARM_TYPE(name, "string")
 293
 294 /**
 295  * parameq - checks if two parameter names match
 296  * @name1: parameter name 1
 297  * @name2: parameter name 2
 298  *
 299  * Returns true if the two parameter names are equal.
 300  * Dashes (-) are considered equal to underscores (_).
 301  */
 302 extern bool parameq(const char *name1, const char *name2);
 303
 304 /**
 305  * parameqn - checks if two parameter names match
 306  * @name1: parameter name 1
 307  * @name2: parameter name 2
 308  * @n: the length to compare
 309  *
 310  * Similar to parameq(), except it compares @n characters.
 311  */
 312 extern bool parameqn(const char *name1, const char *name2, size_t n);
 313
 314 /* Called on module insert or kernel boot */
 315 extern int parse_args(const char *name,
 316                       char *args,
 317                       const struct kernel_param *params,
 318                       unsigned num,
 319                       s16 level_min,
 320                       s16 level_max,
 321                       int (*unknown)(char *param, char *val,
 322                               const char *doing));
 323
 324 /* Called by module remove. */
 325 #ifdef CONFIG_SYSFS
 326 extern void destroy_params(const struct kernel_param *params, unsigned num);
 327 #else
 328 static inline void destroy_params(const struct kernel_param *params,
 329                                   unsigned num)
 330 {
 331 }
 332 #endif /* !CONFIG_SYSFS */
 333
 334 /* All the helper functions */
 335 /* The macros to do compile-time type checking stolen from Jakub
 336    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 337 #define __param_check(name, p, type) \
 338         static inline type *__check_##name(void) { return(p); }
 339
 340 extern struct kernel_param_ops param_ops_byte;
 341 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 342 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 343 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 344
 345 extern struct kernel_param_ops param_ops_short;
 346 extern int param_set_short(const char *val, const struct kernel_param *kp);
 347 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 348 #define param_check_short(name, p) __param_check(name, p, short)
 349
 350 extern struct kernel_param_ops param_ops_ushort;
 351 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 352 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 353 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 354
 355 extern struct kernel_param_ops param_ops_int;
 356 extern int param_set_int(const char *val, const struct kernel_param *kp);
 357 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 358 #define param_check_int(name, p) __param_check(name, p, int)
 359
 360 extern struct kernel_param_ops param_ops_uint;
 361 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 362 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 363 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 364
 365 extern struct kernel_param_ops param_ops_long;
 366 extern int param_set_long(const char *val, const struct kernel_param *kp);
 367 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 368 #define param_check_long(name, p) __param_check(name, p, long)
 369
 370 extern struct kernel_param_ops param_ops_ulong;
 371 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 372 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 373 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 374
 375 extern struct kernel_param_ops param_ops_charp;
 376 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 377 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 378 #define param_check_charp(name, p) __param_check(name, p, char *)
 379
 380 /* We used to allow int as well as bool.  We're taking that away! */
 381 extern struct kernel_param_ops param_ops_bool;
 382 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 383 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 384 #define param_check_bool(name, p) __param_check(name, p, bool)
 385
 386 extern struct kernel_param_ops param_ops_invbool;
 387 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 388 extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 389 #define param_check_invbool(name, p) __param_check(name, p, bool)
 390
 391 /* An int, which can only be set like a bool (though it shows as an int). */
 392 extern struct kernel_param_ops param_ops_bint;
 393 extern int param_set_bint(const char *val, const struct kernel_param *kp);
 394 #define param_get_bint param_get_int
 395 #define param_check_bint param_check_int
 396
 397 /**
 398  * module_param_array - a parameter which is an array of some type
 399  * @name: the name of the array variable
 400  * @type: the type, as per module_param()
 401  * @nump: optional pointer filled in with the number written
 402  * @perm: visibility in sysfs
 403  *
 404  * Input and output are as comma-separated values.  Commas inside values
 405  * don't work properly (eg. an array of charp).
 406  *
 407  * ARRAY_SIZE(@name) is used to determine the number of elements in the
 408  * array, so the definition must be visible.
 409  */
 410 #define module_param_array(name, type, nump, perm)              \
 411         module_param_array_named(name, name, type, nump, perm)
 412
 413 /**
 414  * module_param_array_named - renamed parameter which is an array of some type
 415  * @name: a valid C identifier which is the parameter name
 416  * @array: the name of the array variable
 417  * @type: the type, as per module_param()
 418  * @nump: optional pointer filled in with the number written
 419  * @perm: visibility in sysfs
 420  *
 421  * This exposes a different name than the actual variable name.  See
 422  * module_param_named() for why this might be necessary.
 423  */
 424 #define module_param_array_named(name, array, type, nump, perm)         \
 425         param_check_##type(name, &(array)[0]);                          \
 426         static const struct kparam_array __param_arr_##name             \
 427         = { .max = ARRAY_SIZE(array), .num = nump,                      \
 428             .ops = &param_ops_##type,                                   \
 429             .elemsize = sizeof(array[0]), .elem = array };              \
 430         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 431                             &param_array_ops,                           \
 432                             .arr = &__param_arr_##name,                 \
 433                             perm, -1);                                  \
 434         __MODULE_PARM_TYPE(name, "array of " #type)
 435
 436 extern struct kernel_param_ops param_array_ops;
 437
 438 extern struct kernel_param_ops param_ops_string;
 439 extern int param_set_copystring(const char *val, const struct kernel_param *);
 440 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 441
 442 /* for exporting parameters in /sys/parameters */
 443
 444 struct module;
 445
 446 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 447 extern int module_param_sysfs_setup(struct module *mod,
 448                                     const struct kernel_param *kparam,
 449                                     unsigned int num_params);
 450
 451 extern void module_param_sysfs_remove(struct module *mod);
 452 #else
 453 static inline int module_param_sysfs_setup(struct module *mod,
 454                              const struct kernel_param *kparam,
 455                              unsigned int num_params)
 456 {
 457         return 0;
 458 }
 459
 460 static inline void module_param_sysfs_remove(struct module *mod)
 461 { }
 462 #endif
 463
 464 #endif /* _LINUX_MODULE_PARAMS_H */