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
  39/*
  40 * Flags available for kernel_param_ops
  41 *
  42 * NOARG - the parameter allows for no argument (foo instead of foo=1)
  43 */
  44enum {
  45        KERNEL_PARAM_OPS_FL_NOARG = (1 << 0)
  46};
  47
  48struct kernel_param_ops {
  49        /* How the ops should behave */
  50        unsigned int flags;
  51        /* Returns 0, or -errno.  arg is in kp->arg. */
  52        int (*set)(const char *val, const struct kernel_param *kp);
  53        /* Returns length written or -errno.  Buffer is 4k (ie. be short!) */
  54        int (*get)(char *buffer, const struct kernel_param *kp);
  55        /* Optional function to free kp->arg when module unloaded. */
  56        void (*free)(void *arg);
  57};
  58
  59/*
  60 * Flags available for kernel_param
  61 *
  62 * UNSAFE - the parameter is dangerous and setting it will taint the kernel
  63 */
  64enum {
  65        KERNEL_PARAM_FL_UNSAFE = (1 << 0)
  66};
  67
  68struct kernel_param {
  69        const char *name;
  70        struct module *mod;
  71        const struct kernel_param_ops *ops;
  72        const u16 perm;
  73        s8 level;
  74        u8 flags;
  75        union {
  76                void *arg;
  77                const struct kparam_string *str;
  78                const struct kparam_array *arr;
  79        };
  80};
  81
  82extern const struct kernel_param __start___param[], __stop___param[];
  83
  84/* Special one for strings we want to copy into */
  85struct kparam_string {
  86        unsigned int maxlen;
  87        char *string;
  88};
  89
  90/* Special one for arrays */
  91struct kparam_array
  92{
  93        unsigned int max;
  94        unsigned int elemsize;
  95        unsigned int *num;
  96        const struct kernel_param_ops *ops;
  97        void *elem;
  98};
  99
 100/**
 101 * module_param - typesafe helper for a module/cmdline parameter
 102 * @value: the variable to alter, and exposed parameter name.
 103 * @type: the type of the parameter
 104 * @perm: visibility in sysfs.
 105 *
 106 * @value becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
 107 * ".") the kernel commandline parameter.  Note that - is changed to _, so
 108 * the user can use "foo-bar=1" even for variable "foo_bar".
 109 *
 110 * @perm is 0 if the the variable is not to appear in sysfs, or 0444
 111 * for world-readable, 0644 for root-writable, etc.  Note that if it
 112 * is writable, you may need to use kernel_param_lock() around
 113 * accesses (esp. charp, which can be kfreed when it changes).
 114 *
 115 * The @type is simply pasted to refer to a param_ops_##type and a
 116 * param_check_##type: for convenience many standard types are provided but
 117 * you can create your own by defining those variables.
 118 *
 119 * Standard types are:
 120 *      byte, short, ushort, int, uint, long, ulong
 121 *      charp: a character pointer
 122 *      bool: a bool, values 0/1, y/n, Y/N.
 123 *      invbool: the above, only sense-reversed (N = true).
 124 */
 125#define module_param(name, type, perm)                          \
 126        module_param_named(name, name, type, perm)
 127
 128/**
 129 * module_param_unsafe - same as module_param but taints kernel
 130 */
 131#define module_param_unsafe(name, type, perm)                   \
 132        module_param_named_unsafe(name, name, type, perm)
 133
 134/**
 135 * module_param_named - typesafe helper for a renamed module/cmdline parameter
 136 * @name: a valid C identifier which is the parameter name.
 137 * @value: the actual lvalue to alter.
 138 * @type: the type of the parameter
 139 * @perm: visibility in sysfs.
 140 *
 141 * Usually it's a good idea to have variable names and user-exposed names the
 142 * same, but that's harder if the variable must be non-static or is inside a
 143 * structure.  This allows exposure under a different name.
 144 */
 145#define module_param_named(name, value, type, perm)                        \
 146        param_check_##type(name, &(value));                                \
 147        module_param_cb(name, &param_ops_##type, &value, perm);            \
 148        __MODULE_PARM_TYPE(name, #type)
 149
 150/**
 151 * module_param_named_unsafe - same as module_param_named but taints kernel
 152 */
 153#define module_param_named_unsafe(name, value, type, perm)              \
 154        param_check_##type(name, &(value));                             \
 155        module_param_cb_unsafe(name, &param_ops_##type, &value, perm);  \
 156        __MODULE_PARM_TYPE(name, #type)
 157
 158/**
 159 * module_param_cb - general callback for a module/cmdline parameter
 160 * @name: a valid C identifier which is the parameter name.
 161 * @ops: the set & get operations for this parameter.
 162 * @perm: visibility in sysfs.
 163 *
 164 * The ops can have NULL set or get functions.
 165 */
 166#define module_param_cb(name, ops, arg, perm)                                 \
 167        __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1, 0)
 168
 169#define module_param_cb_unsafe(name, ops, arg, perm)                          \
 170        __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1,    \
 171                            KERNEL_PARAM_FL_UNSAFE)
 172
 173/**
 174 * <level>_param_cb - general callback for a module/cmdline parameter
 175 *                    to be evaluated before certain initcall level
 176 * @name: a valid C identifier which is the parameter name.
 177 * @ops: the set & get operations for this parameter.
 178 * @perm: visibility in sysfs.
 179 *
 180 * The ops can have NULL set or get functions.
 181 */
 182#define __level_param_cb(name, ops, arg, perm, level)                   \
 183        __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, level, 0)
 184
 185#define core_param_cb(name, ops, arg, perm)             \
 186        __level_param_cb(name, ops, arg, perm, 1)
 187
 188#define postcore_param_cb(name, ops, arg, perm)         \
 189        __level_param_cb(name, ops, arg, perm, 2)
 190
 191#define arch_param_cb(name, ops, arg, perm)             \
 192        __level_param_cb(name, ops, arg, perm, 3)
 193
 194#define subsys_param_cb(name, ops, arg, perm)           \
 195        __level_param_cb(name, ops, arg, perm, 4)
 196
 197#define fs_param_cb(name, ops, arg, perm)               \
 198        __level_param_cb(name, ops, arg, perm, 5)
 199
 200#define device_param_cb(name, ops, arg, perm)           \
 201        __level_param_cb(name, ops, arg, perm, 6)
 202
 203#define late_param_cb(name, ops, arg, perm)             \
 204        __level_param_cb(name, ops, arg, perm, 7)
 205
 206/* On alpha, ia64 and ppc64 relocations to global data cannot go into
 207   read-only sections (which is part of respective UNIX ABI on these
 208   platforms). So 'const' makes no sense and even causes compile failures
 209   with some compilers. */
 210#if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
 211#define __moduleparam_const
 212#else
 213#define __moduleparam_const const
 214#endif
 215
 216/* This is the fundamental function for registering boot/module
 217   parameters. */
 218#define __module_param_call(prefix, name, ops, arg, perm, level, flags) \
 219        /* Default value instead of permissions? */                     \
 220        static const char __param_str_##name[] = prefix #name;          \
 221        static struct kernel_param __moduleparam_const __param_##name   \
 222        __used                                                          \
 223    __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
 224        = { __param_str_##name, THIS_MODULE, ops,                       \
 225            VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } }
 226
 227/* Obsolete - use module_param_cb() */
 228#define module_param_call(name, set, get, arg, perm)                    \
 229        static const struct kernel_param_ops __param_ops_##name =               \
 230                { .flags = 0, (void *)set, (void *)get };               \
 231        __module_param_call(MODULE_PARAM_PREFIX,                        \
 232                            name, &__param_ops_##name, arg,             \
 233                            (perm) + sizeof(__check_old_set_param(set))*0, -1, 0)
 234
 235/* We don't get oldget: it's often a new-style param_get_uint, etc. */
 236static inline int
 237__check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 238{
 239        return 0;
 240}
 241
 242#ifdef CONFIG_SYSFS
 243extern void kernel_param_lock(struct module *mod);
 244extern void kernel_param_unlock(struct module *mod);
 245#else
 246static inline void kernel_param_lock(struct module *mod)
 247{
 248}
 249static inline void kernel_param_unlock(struct module *mod)
 250{
 251}
 252#endif
 253
 254#ifndef MODULE
 255/**
 256 * core_param - define a historical core kernel parameter.
 257 * @name: the name of the cmdline and sysfs parameter (often the same as var)
 258 * @var: the variable
 259 * @type: the type of the parameter
 260 * @perm: visibility in sysfs
 261 *
 262 * core_param is just like module_param(), but cannot be modular and
 263 * doesn't add a prefix (such as "printk.").  This is for compatibility
 264 * with __setup(), and it makes sense as truly core parameters aren't
 265 * tied to the particular file they're in.
 266 */
 267#define core_param(name, var, type, perm)                               \
 268        param_check_##type(name, &(var));                               \
 269        __module_param_call("", name, &param_ops_##type, &var, perm, -1, 0)
 270
 271/**
 272 * core_param_unsafe - same as core_param but taints kernel
 273 */
 274#define core_param_unsafe(name, var, type, perm)                \
 275        param_check_##type(name, &(var));                               \
 276        __module_param_call("", name, &param_ops_##type, &var, perm,    \
 277                            -1, KERNEL_PARAM_FL_UNSAFE)
 278
 279#endif /* !MODULE */
 280
 281/**
 282 * module_param_string - a char array parameter
 283 * @name: the name of the parameter
 284 * @string: the string variable
 285 * @len: the maximum length of the string, incl. terminator
 286 * @perm: visibility in sysfs.
 287 *
 288 * This actually copies the string when it's set (unlike type charp).
 289 * @len is usually just sizeof(string).
 290 */
 291#define module_param_string(name, string, len, perm)                    \
 292        static const struct kparam_string __param_string_##name         \
 293                = { len, string };                                      \
 294        __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 295                            &param_ops_string,                          \
 296                            .str = &__param_string_##name, perm, -1, 0);\
 297        __MODULE_PARM_TYPE(name, "string")
 298
 299/**
 300 * parameq - checks if two parameter names match
 301 * @name1: parameter name 1
 302 * @name2: parameter name 2
 303 *
 304 * Returns true if the two parameter names are equal.
 305 * Dashes (-) are considered equal to underscores (_).
 306 */
 307extern bool parameq(const char *name1, const char *name2);
 308
 309/**
 310 * parameqn - checks if two parameter names match
 311 * @name1: parameter name 1
 312 * @name2: parameter name 2
 313 * @n: the length to compare
 314 *
 315 * Similar to parameq(), except it compares @n characters.
 316 */
 317extern bool parameqn(const char *name1, const char *name2, size_t n);
 318
 319/* Called on module insert or kernel boot */
 320extern char *parse_args(const char *name,
 321                      char *args,
 322                      const struct kernel_param *params,
 323                      unsigned num,
 324                      s16 level_min,
 325                      s16 level_max,
 326                      void *arg,
 327                      int (*unknown)(char *param, char *val,
 328                                     const char *doing, void *arg));
 329
 330/* Called by module remove. */
 331#ifdef CONFIG_SYSFS
 332extern void destroy_params(const struct kernel_param *params, unsigned num);
 333#else
 334static inline void destroy_params(const struct kernel_param *params,
 335                                  unsigned num)
 336{
 337}
 338#endif /* !CONFIG_SYSFS */
 339
 340/* All the helper functions */
 341/* The macros to do compile-time type checking stolen from Jakub
 342   Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 343#define __param_check(name, p, type) \
 344        static inline type __always_unused *__check_##name(void) { return(p); }
 345
 346extern const struct kernel_param_ops param_ops_byte;
 347extern int param_set_byte(const char *val, const struct kernel_param *kp);
 348extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 349#define param_check_byte(name, p) __param_check(name, p, unsigned char)
 350
 351extern const struct kernel_param_ops param_ops_short;
 352extern int param_set_short(const char *val, const struct kernel_param *kp);
 353extern int param_get_short(char *buffer, const struct kernel_param *kp);
 354#define param_check_short(name, p) __param_check(name, p, short)
 355
 356extern const struct kernel_param_ops param_ops_ushort;
 357extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 358extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 359#define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 360
 361extern const struct kernel_param_ops param_ops_int;
 362extern int param_set_int(const char *val, const struct kernel_param *kp);
 363extern int param_get_int(char *buffer, const struct kernel_param *kp);
 364#define param_check_int(name, p) __param_check(name, p, int)
 365
 366extern const struct kernel_param_ops param_ops_uint;
 367extern int param_set_uint(const char *val, const struct kernel_param *kp);
 368extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 369#define param_check_uint(name, p) __param_check(name, p, unsigned int)
 370
 371extern const struct kernel_param_ops param_ops_long;
 372extern int param_set_long(const char *val, const struct kernel_param *kp);
 373extern int param_get_long(char *buffer, const struct kernel_param *kp);
 374#define param_check_long(name, p) __param_check(name, p, long)
 375
 376extern const struct kernel_param_ops param_ops_ulong;
 377extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 378extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 379#define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 380
 381extern const struct kernel_param_ops param_ops_ullong;
 382extern int param_set_ullong(const char *val, const struct kernel_param *kp);
 383extern int param_get_ullong(char *buffer, const struct kernel_param *kp);
 384#define param_check_ullong(name, p) __param_check(name, p, unsigned long long)
 385
 386extern const struct kernel_param_ops param_ops_charp;
 387extern int param_set_charp(const char *val, const struct kernel_param *kp);
 388extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 389extern void param_free_charp(void *arg);
 390#define param_check_charp(name, p) __param_check(name, p, char *)
 391
 392/* We used to allow int as well as bool.  We're taking that away! */
 393extern const struct kernel_param_ops param_ops_bool;
 394extern int param_set_bool(const char *val, const struct kernel_param *kp);
 395extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 396#define param_check_bool(name, p) __param_check(name, p, bool)
 397
 398extern const struct kernel_param_ops param_ops_bool_enable_only;
 399extern int param_set_bool_enable_only(const char *val,
 400                                      const struct kernel_param *kp);
 401/* getter is the same as for the regular bool */
 402#define param_check_bool_enable_only param_check_bool
 403
 404extern const struct kernel_param_ops param_ops_invbool;
 405extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 406extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 407#define param_check_invbool(name, p) __param_check(name, p, bool)
 408
 409/* An int, which can only be set like a bool (though it shows as an int). */
 410extern const struct kernel_param_ops param_ops_bint;
 411extern int param_set_bint(const char *val, const struct kernel_param *kp);
 412#define param_get_bint param_get_int
 413#define param_check_bint param_check_int
 414
 415/**
 416 * module_param_array - a parameter which is an array of some type
 417 * @name: 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 * Input and output are as comma-separated values.  Commas inside values
 423 * don't work properly (eg. an array of charp).
 424 *
 425 * ARRAY_SIZE(@name) is used to determine the number of elements in the
 426 * array, so the definition must be visible.
 427 */
 428#define module_param_array(name, type, nump, perm)              \
 429        module_param_array_named(name, name, type, nump, perm)
 430
 431/**
 432 * module_param_array_named - renamed parameter which is an array of some type
 433 * @name: a valid C identifier which is the parameter name
 434 * @array: the name of the array variable
 435 * @type: the type, as per module_param()
 436 * @nump: optional pointer filled in with the number written
 437 * @perm: visibility in sysfs
 438 *
 439 * This exposes a different name than the actual variable name.  See
 440 * module_param_named() for why this might be necessary.
 441 */
 442#define module_param_array_named(name, array, type, nump, perm)         \
 443        param_check_##type(name, &(array)[0]);                          \
 444        static const struct kparam_array __param_arr_##name             \
 445        = { .max = ARRAY_SIZE(array), .num = nump,                      \
 446            .ops = &param_ops_##type,                                   \
 447            .elemsize = sizeof(array[0]), .elem = array };              \
 448        __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 449                            &param_array_ops,                           \
 450                            .arr = &__param_arr_##name,                 \
 451                            perm, -1, 0);                               \
 452        __MODULE_PARM_TYPE(name, "array of " #type)
 453
 454extern const struct kernel_param_ops param_array_ops;
 455
 456extern const struct kernel_param_ops param_ops_string;
 457extern int param_set_copystring(const char *val, const struct kernel_param *);
 458extern int param_get_string(char *buffer, const struct kernel_param *kp);
 459
 460/* for exporting parameters in /sys/module/.../parameters */
 461
 462struct module;
 463
 464#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 465extern int module_param_sysfs_setup(struct module *mod,
 466                                    const struct kernel_param *kparam,
 467                                    unsigned int num_params);
 468
 469extern void module_param_sysfs_remove(struct module *mod);
 470#else
 471static inline int module_param_sysfs_setup(struct module *mod,
 472                             const struct kernel_param *kparam,
 473                             unsigned int num_params)
 474{
 475        return 0;
 476}
 477
 478static inline void module_param_sysfs_remove(struct module *mod)
 479{ }
 480#endif
 481
 482#endif /* _LINUX_MODULE_PARAMS_H */
 483