linux/include/linux/moduleparam.h
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   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)                                    \
  23static 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
  39struct kernel_param;
  40
  41struct 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
  50struct 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 */
  63struct kparam_string {
  64        unsigned int maxlen;
  65        char *string;
  66};
  67
  68/* Special one for arrays */
  69struct 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, -1)
 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, -1)
 196
 197/* We don't get oldget: it's often a new-style param_get_uint, etc. */
 198static 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
 249extern void __kernel_param_lock(void);
 250extern void __kernel_param_unlock(void);
 251#else
 252static inline void __kernel_param_lock(void)
 253{
 254}
 255static 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, -1)
 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, -1);   \
 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 */
 304extern 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 */
 314extern bool parameqn(const char *name1, const char *name2, size_t n);
 315
 316/* Called on module insert or kernel boot */
 317extern 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                              const char *doing));
 325
 326/* Called by module remove. */
 327#ifdef CONFIG_SYSFS
 328extern void destroy_params(const struct kernel_param *params, unsigned num);
 329#else
 330static inline void destroy_params(const struct kernel_param *params,
 331                                  unsigned num)
 332{
 333}
 334#endif /* !CONFIG_SYSFS */
 335
 336/* All the helper functions */
 337/* The macros to do compile-time type checking stolen from Jakub
 338   Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 339#define __param_check(name, p, type) \
 340        static inline type *__check_##name(void) { return(p); }
 341
 342extern struct kernel_param_ops param_ops_byte;
 343extern int param_set_byte(const char *val, const struct kernel_param *kp);
 344extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 345#define param_check_byte(name, p) __param_check(name, p, unsigned char)
 346
 347extern struct kernel_param_ops param_ops_short;
 348extern int param_set_short(const char *val, const struct kernel_param *kp);
 349extern int param_get_short(char *buffer, const struct kernel_param *kp);
 350#define param_check_short(name, p) __param_check(name, p, short)
 351
 352extern struct kernel_param_ops param_ops_ushort;
 353extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 354extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 355#define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 356
 357extern struct kernel_param_ops param_ops_int;
 358extern int param_set_int(const char *val, const struct kernel_param *kp);
 359extern int param_get_int(char *buffer, const struct kernel_param *kp);
 360#define param_check_int(name, p) __param_check(name, p, int)
 361
 362extern struct kernel_param_ops param_ops_uint;
 363extern int param_set_uint(const char *val, const struct kernel_param *kp);
 364extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 365#define param_check_uint(name, p) __param_check(name, p, unsigned int)
 366
 367extern struct kernel_param_ops param_ops_long;
 368extern int param_set_long(const char *val, const struct kernel_param *kp);
 369extern int param_get_long(char *buffer, const struct kernel_param *kp);
 370#define param_check_long(name, p) __param_check(name, p, long)
 371
 372extern struct kernel_param_ops param_ops_ulong;
 373extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 374extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 375#define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 376
 377extern struct kernel_param_ops param_ops_charp;
 378extern int param_set_charp(const char *val, const struct kernel_param *kp);
 379extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 380#define param_check_charp(name, p) __param_check(name, p, char *)
 381
 382/* We used to allow int as well as bool.  We're taking that away! */
 383extern struct kernel_param_ops param_ops_bool;
 384extern int param_set_bool(const char *val, const struct kernel_param *kp);
 385extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 386#define param_check_bool(name, p) __param_check(name, p, bool)
 387
 388extern struct kernel_param_ops param_ops_invbool;
 389extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 390extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 391#define param_check_invbool(name, p) __param_check(name, p, bool)
 392
 393/* An int, which can only be set like a bool (though it shows as an int). */
 394extern struct kernel_param_ops param_ops_bint;
 395extern int param_set_bint(const char *val, const struct kernel_param *kp);
 396#define param_get_bint param_get_int
 397#define param_check_bint param_check_int
 398
 399/**
 400 * module_param_array - a parameter which is an array of some type
 401 * @name: the name of the array variable
 402 * @type: the type, as per module_param()
 403 * @nump: optional pointer filled in with the number written
 404 * @perm: visibility in sysfs
 405 *
 406 * Input and output are as comma-separated values.  Commas inside values
 407 * don't work properly (eg. an array of charp).
 408 *
 409 * ARRAY_SIZE(@name) is used to determine the number of elements in the
 410 * array, so the definition must be visible.
 411 */
 412#define module_param_array(name, type, nump, perm)              \
 413        module_param_array_named(name, name, type, nump, perm)
 414
 415/**
 416 * module_param_array_named - renamed parameter which is an array of some type
 417 * @name: a valid C identifier which is the parameter name
 418 * @array: the name of the array variable
 419 * @type: the type, as per module_param()
 420 * @nump: optional pointer filled in with the number written
 421 * @perm: visibility in sysfs
 422 *
 423 * This exposes a different name than the actual variable name.  See
 424 * module_param_named() for why this might be necessary.
 425 */
 426#define module_param_array_named(name, array, type, nump, perm)         \
 427        param_check_##type(name, &(array)[0]);                          \
 428        static const struct kparam_array __param_arr_##name             \
 429        = { .max = ARRAY_SIZE(array), .num = nump,                      \
 430            .ops = &param_ops_##type,                                   \
 431            .elemsize = sizeof(array[0]), .elem = array };              \
 432        __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 433                            &param_array_ops,                           \
 434                            .arr = &__param_arr_##name,                 \
 435                            perm, -1);                                  \
 436        __MODULE_PARM_TYPE(name, "array of " #type)
 437
 438extern struct kernel_param_ops param_array_ops;
 439
 440extern struct kernel_param_ops param_ops_string;
 441extern int param_set_copystring(const char *val, const struct kernel_param *);
 442extern int param_get_string(char *buffer, const struct kernel_param *kp);
 443
 444/* for exporting parameters in /sys/parameters */
 445
 446struct module;
 447
 448#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 449extern int module_param_sysfs_setup(struct module *mod,
 450                                    const struct kernel_param *kparam,
 451                                    unsigned int num_params);
 452
 453extern void module_param_sysfs_remove(struct module *mod);
 454#else
 455static inline int module_param_sysfs_setup(struct module *mod,
 456                             const struct kernel_param *kparam,
 457                             unsigned int num_params)
 458{
 459        return 0;
 460}
 461
 462static inline void module_param_sysfs_remove(struct module *mod)
 463{ }
 464#endif
 465
 466#endif /* _LINUX_MODULE_PARAMS_H */
 467
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