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 /*
  40  * Flags available for kernel_param_ops
  41  *
  42  * NOARG - the parameter allows for no argument (foo instead of foo=1)
  43  */
  44 enum {
  45         KERNEL_PARAM_OPS_FL_NOARG = (1 << 0)
  46 };
  47
  48 struct 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  */
  64 enum {
  65         KERNEL_PARAM_FL_UNSAFE = (1 << 0)
  66 };
  67
  68 struct 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
  82 extern const struct kernel_param __start___param[], __stop___param[];
  83
  84 /* Special one for strings we want to copy into */
  85 struct kparam_string {
  86         unsigned int maxlen;
  87         char *string;
  88 };
  89
  90 /* Special one for arrays */
  91 struct 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. */
 236 static inline int
 237 __check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 238 {
 239         return 0;
 240 }
 241
 242 #ifdef CONFIG_SYSFS
 243 extern void kernel_param_lock(struct module *mod);
 244 extern void kernel_param_unlock(struct module *mod);
 245 #else
 246 static inline void kernel_param_lock(struct module *mod)
 247 {
 248 }
 249 static 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  */
 307 extern 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  */
 317 extern bool parameqn(const char *name1, const char *name2, size_t n);
 318
 319 /* Called on module insert or kernel boot */
 320 extern 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
 332 extern void destroy_params(const struct kernel_param *params, unsigned num);
 333 #else
 334 static 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
 346 extern const struct kernel_param_ops param_ops_byte;
 347 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 348 extern 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
 351 extern const struct kernel_param_ops param_ops_short;
 352 extern int param_set_short(const char *val, const struct kernel_param *kp);
 353 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 354 #define param_check_short(name, p) __param_check(name, p, short)
 355
 356 extern const struct kernel_param_ops param_ops_ushort;
 357 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 358 extern 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
 361 extern const struct kernel_param_ops param_ops_int;
 362 extern int param_set_int(const char *val, const struct kernel_param *kp);
 363 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 364 #define param_check_int(name, p) __param_check(name, p, int)
 365
 366 extern const struct kernel_param_ops param_ops_uint;
 367 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 368 extern 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
 371 extern const struct kernel_param_ops param_ops_long;
 372 extern int param_set_long(const char *val, const struct kernel_param *kp);
 373 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 374 #define param_check_long(name, p) __param_check(name, p, long)
 375
 376 extern const struct kernel_param_ops param_ops_ulong;
 377 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 378 extern 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
 381 extern const struct kernel_param_ops param_ops_ullong;
 382 extern int param_set_ullong(const char *val, const struct kernel_param *kp);
 383 extern 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
 386 extern const struct kernel_param_ops param_ops_charp;
 387 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 388 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 389 extern 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! */
 393 extern const struct kernel_param_ops param_ops_bool;
 394 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 395 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 396 #define param_check_bool(name, p) __param_check(name, p, bool)
 397
 398 extern const struct kernel_param_ops param_ops_bool_enable_only;
 399 extern 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
 404 extern const struct kernel_param_ops param_ops_invbool;
 405 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 406 extern 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). */
 410 extern const struct kernel_param_ops param_ops_bint;
 411 extern 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
 454 extern const struct kernel_param_ops param_array_ops;
 455
 456 extern const struct kernel_param_ops param_ops_string;
 457 extern int param_set_copystring(const char *val, const struct kernel_param *);
 458 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 459
 460 /* for exporting parameters in /sys/module/.../parameters */
 461
 462 struct module;
 463
 464 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 465 extern int module_param_sysfs_setup(struct module *mod,
 466                                     const struct kernel_param *kparam,
 467                                     unsigned int num_params);
 468
 469 extern void module_param_sysfs_remove(struct module *mod);
 470 #else
 471 static 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
 478 static inline void module_param_sysfs_remove(struct module *mod)
 479 { }
 480 #endif
 481
 482 #endif /* _LINUX_MODULE_PARAMS_H */