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#ifdef MODULE
  20#define __MODULE_INFO(tag, name, info)                                    \
  21static 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
  37struct kernel_param;
  38
  39struct 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
  48struct 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 */
  61struct kparam_string {
  62        unsigned int maxlen;
  63        char *string;
  64};
  65
  66/* Special one for arrays */
  67struct 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. */
 196static 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
 247extern void __kernel_param_lock(void);
 248extern void __kernel_param_unlock(void);
 249#else
 250static inline void __kernel_param_lock(void)
 251{
 252}
 253static 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 */
 302extern 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 */
 312extern bool parameqn(const char *name1, const char *name2, size_t n);
 313
 314/* Called on module insert or kernel boot */
 315extern 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
 326extern void destroy_params(const struct kernel_param *params, unsigned num);
 327#else
 328static 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
 340extern struct kernel_param_ops param_ops_byte;
 341extern int param_set_byte(const char *val, const struct kernel_param *kp);
 342extern 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
 345extern struct kernel_param_ops param_ops_short;
 346extern int param_set_short(const char *val, const struct kernel_param *kp);
 347extern int param_get_short(char *buffer, const struct kernel_param *kp);
 348#define param_check_short(name, p) __param_check(name, p, short)
 349
 350extern struct kernel_param_ops param_ops_ushort;
 351extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 352extern 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
 355extern struct kernel_param_ops param_ops_int;
 356extern int param_set_int(const char *val, const struct kernel_param *kp);
 357extern int param_get_int(char *buffer, const struct kernel_param *kp);
 358#define param_check_int(name, p) __param_check(name, p, int)
 359
 360extern struct kernel_param_ops param_ops_uint;
 361extern int param_set_uint(const char *val, const struct kernel_param *kp);
 362extern 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
 365extern struct kernel_param_ops param_ops_long;
 366extern int param_set_long(const char *val, const struct kernel_param *kp);
 367extern int param_get_long(char *buffer, const struct kernel_param *kp);
 368#define param_check_long(name, p) __param_check(name, p, long)
 369
 370extern struct kernel_param_ops param_ops_ulong;
 371extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 372extern 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
 375extern struct kernel_param_ops param_ops_charp;
 376extern int param_set_charp(const char *val, const struct kernel_param *kp);
 377extern 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! */
 381extern struct kernel_param_ops param_ops_bool;
 382extern int param_set_bool(const char *val, const struct kernel_param *kp);
 383extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 384#define param_check_bool(name, p) __param_check(name, p, bool)
 385
 386extern struct kernel_param_ops param_ops_invbool;
 387extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 388extern 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). */
 392extern struct kernel_param_ops param_ops_bint;
 393extern 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
 436extern struct kernel_param_ops param_array_ops;
 437
 438extern struct kernel_param_ops param_ops_string;
 439extern int param_set_copystring(const char *val, const struct kernel_param *);
 440extern int param_get_string(char *buffer, const struct kernel_param *kp);
 441
 442/* for exporting parameters in /sys/parameters */
 443
 444struct module;
 445
 446#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 447extern int module_param_sysfs_setup(struct module *mod,
 448                                    const struct kernel_param *kparam,
 449                                    unsigned int num_params);
 450
 451extern void module_param_sysfs_remove(struct module *mod);
 452#else
 453static 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
 460static inline void module_param_sysfs_remove(struct module *mod)
 461{ }
 462#endif
 463
 464#endif /* _LINUX_MODULE_PARAMS_H */
 465
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