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