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_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 struct kernel_param {
  60         const char *name;
  61         const struct kernel_param_ops *ops;
  62         u16 perm;
  63         s16 level;
  64         union {
  65                 void *arg;
  66                 const struct kparam_string *str;
  67                 const struct kparam_array *arr;
  68         };
  69 };
  70
  71 /* Special one for strings we want to copy into */
  72 struct kparam_string {
  73         unsigned int maxlen;
  74         char *string;
  75 };
  76
  77 /* Special one for arrays */
  78 struct kparam_array
  79 {
  80         unsigned int max;
  81         unsigned int elemsize;
  82         unsigned int *num;
  83         const struct kernel_param_ops *ops;
  84         void *elem;
  85 };
  86
  87 /**
  88  * module_param - typesafe helper for a module/cmdline parameter
  89  * @value: the variable to alter, and exposed parameter name.
  90  * @type: the type of the parameter
  91  * @perm: visibility in sysfs.
  92  *
  93  * @value becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
  94  * ".") the kernel commandline parameter.  Note that - is changed to _, so
  95  * the user can use "foo-bar=1" even for variable "foo_bar".
  96  *
  97  * @perm is 0 if the the variable is not to appear in sysfs, or 0444
  98  * for world-readable, 0644 for root-writable, etc.  Note that if it
  99  * is writable, you may need to use kparam_block_sysfs_write() around
 100  * accesses (esp. charp, which can be kfreed when it changes).
 101  *
 102  * The @type is simply pasted to refer to a param_ops_##type and a
 103  * param_check_##type: for convenience many standard types are provided but
 104  * you can create your own by defining those variables.
 105  *
 106  * Standard types are:
 107  *      byte, short, ushort, int, uint, long, ulong
 108  *      charp: a character pointer
 109  *      bool: a bool, values 0/1, y/n, Y/N.
 110  *      invbool: the above, only sense-reversed (N = true).
 111  */
 112 #define module_param(name, type, perm)                          \
 113         module_param_named(name, name, type, perm)
 114
 115 /**
 116  * module_param_named - typesafe helper for a renamed module/cmdline parameter
 117  * @name: a valid C identifier which is the parameter name.
 118  * @value: the actual lvalue to alter.
 119  * @type: the type of the parameter
 120  * @perm: visibility in sysfs.
 121  *
 122  * Usually it's a good idea to have variable names and user-exposed names the
 123  * same, but that's harder if the variable must be non-static or is inside a
 124  * structure.  This allows exposure under a different name.
 125  */
 126 #define module_param_named(name, value, type, perm)                        \
 127         param_check_##type(name, &(value));                                \
 128         module_param_cb(name, &param_ops_##type, &value, perm);            \
 129         __MODULE_PARM_TYPE(name, #type)
 130
 131 /**
 132  * module_param_cb - general callback for a module/cmdline parameter
 133  * @name: a valid C identifier which is the parameter name.
 134  * @ops: the set & get operations for this parameter.
 135  * @perm: visibility in sysfs.
 136  *
 137  * The ops can have NULL set or get functions.
 138  */
 139 #define module_param_cb(name, ops, arg, perm)                                 \
 140         __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1)
 141
 142 /**
 143  * <level>_param_cb - general callback for a module/cmdline parameter
 144  *                    to be evaluated before certain initcall level
 145  * @name: a valid C identifier which is the parameter name.
 146  * @ops: the set & get operations for this parameter.
 147  * @perm: visibility in sysfs.
 148  *
 149  * The ops can have NULL set or get functions.
 150  */
 151 #define __level_param_cb(name, ops, arg, perm, level)                   \
 152         __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, level)
 153
 154 #define core_param_cb(name, ops, arg, perm)             \
 155         __level_param_cb(name, ops, arg, perm, 1)
 156
 157 #define postcore_param_cb(name, ops, arg, perm)         \
 158         __level_param_cb(name, ops, arg, perm, 2)
 159
 160 #define arch_param_cb(name, ops, arg, perm)             \
 161         __level_param_cb(name, ops, arg, perm, 3)
 162
 163 #define subsys_param_cb(name, ops, arg, perm)           \
 164         __level_param_cb(name, ops, arg, perm, 4)
 165
 166 #define fs_param_cb(name, ops, arg, perm)               \
 167         __level_param_cb(name, ops, arg, perm, 5)
 168
 169 #define device_param_cb(name, ops, arg, perm)           \
 170         __level_param_cb(name, ops, arg, perm, 6)
 171
 172 #define late_param_cb(name, ops, arg, perm)             \
 173         __level_param_cb(name, ops, arg, perm, 7)
 174
 175 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
 176    read-only sections (which is part of respective UNIX ABI on these
 177    platforms). So 'const' makes no sense and even causes compile failures
 178    with some compilers. */
 179 #if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
 180 #define __moduleparam_const
 181 #else
 182 #define __moduleparam_const const
 183 #endif
 184
 185 /* This is the fundamental function for registering boot/module
 186    parameters. */
 187 #define __module_param_call(prefix, name, ops, arg, perm, level)        \
 188         /* Default value instead of permissions? */                     \
 189         static int __param_perm_check_##name __attribute__((unused)) =  \
 190         BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
 191         + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
 192         static const char __param_str_##name[] = prefix #name;          \
 193         static struct kernel_param __moduleparam_const __param_##name   \
 194         __used                                                          \
 195     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
 196         = { __param_str_##name, ops, perm, level, { arg } }
 197
 198 /* Obsolete - use module_param_cb() */
 199 #define module_param_call(name, set, get, arg, perm)                    \
 200         static struct kernel_param_ops __param_ops_##name =             \
 201                 { 0, (void *)set, (void *)get };                        \
 202         __module_param_call(MODULE_PARAM_PREFIX,                        \
 203                             name, &__param_ops_##name, arg,             \
 204                             (perm) + sizeof(__check_old_set_param(set))*0, -1)
 205
 206 /* We don't get oldget: it's often a new-style param_get_uint, etc. */
 207 static inline int
 208 __check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 209 {
 210         return 0;
 211 }
 212
 213 /**
 214  * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
 215  * @name: the name of the parameter
 216  *
 217  * There's no point blocking write on a paramter that isn't writable via sysfs!
 218  */
 219 #define kparam_block_sysfs_write(name)                  \
 220         do {                                            \
 221                 BUG_ON(!(__param_##name.perm & 0222));  \
 222                 __kernel_param_lock();                  \
 223         } while (0)
 224
 225 /**
 226  * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
 227  * @name: the name of the parameter
 228  */
 229 #define kparam_unblock_sysfs_write(name)                \
 230         do {                                            \
 231                 BUG_ON(!(__param_##name.perm & 0222));  \
 232                 __kernel_param_unlock();                \
 233         } while (0)
 234
 235 /**
 236  * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
 237  * @name: the name of the parameter
 238  *
 239  * This also blocks sysfs writes.
 240  */
 241 #define kparam_block_sysfs_read(name)                   \
 242         do {                                            \
 243                 BUG_ON(!(__param_##name.perm & 0444));  \
 244                 __kernel_param_lock();                  \
 245         } while (0)
 246
 247 /**
 248  * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
 249  * @name: the name of the parameter
 250  */
 251 #define kparam_unblock_sysfs_read(name)                 \
 252         do {                                            \
 253                 BUG_ON(!(__param_##name.perm & 0444));  \
 254                 __kernel_param_unlock();                \
 255         } while (0)
 256
 257 #ifdef CONFIG_SYSFS
 258 extern void __kernel_param_lock(void);
 259 extern void __kernel_param_unlock(void);
 260 #else
 261 static inline void __kernel_param_lock(void)
 262 {
 263 }
 264 static inline void __kernel_param_unlock(void)
 265 {
 266 }
 267 #endif
 268
 269 #ifndef MODULE
 270 /**
 271  * core_param - define a historical core kernel parameter.
 272  * @name: the name of the cmdline and sysfs parameter (often the same as var)
 273  * @var: the variable
 274  * @type: the type of the parameter
 275  * @perm: visibility in sysfs
 276  *
 277  * core_param is just like module_param(), but cannot be modular and
 278  * doesn't add a prefix (such as "printk.").  This is for compatibility
 279  * with __setup(), and it makes sense as truly core parameters aren't
 280  * tied to the particular file they're in.
 281  */
 282 #define core_param(name, var, type, perm)                               \
 283         param_check_##type(name, &(var));                               \
 284         __module_param_call("", name, &param_ops_##type, &var, perm, -1)
 285 #endif /* !MODULE */
 286
 287 /**
 288  * module_param_string - a char array parameter
 289  * @name: the name of the parameter
 290  * @string: the string variable
 291  * @len: the maximum length of the string, incl. terminator
 292  * @perm: visibility in sysfs.
 293  *
 294  * This actually copies the string when it's set (unlike type charp).
 295  * @len is usually just sizeof(string).
 296  */
 297 #define module_param_string(name, string, len, perm)                    \
 298         static const struct kparam_string __param_string_##name         \
 299                 = { len, string };                                      \
 300         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 301                             &param_ops_string,                          \
 302                             .str = &__param_string_##name, perm, -1);   \
 303         __MODULE_PARM_TYPE(name, "string")
 304
 305 /**
 306  * parameq - checks if two parameter names match
 307  * @name1: parameter name 1
 308  * @name2: parameter name 2
 309  *
 310  * Returns true if the two parameter names are equal.
 311  * Dashes (-) are considered equal to underscores (_).
 312  */
 313 extern bool parameq(const char *name1, const char *name2);
 314
 315 /**
 316  * parameqn - checks if two parameter names match
 317  * @name1: parameter name 1
 318  * @name2: parameter name 2
 319  * @n: the length to compare
 320  *
 321  * Similar to parameq(), except it compares @n characters.
 322  */
 323 extern bool parameqn(const char *name1, const char *name2, size_t n);
 324
 325 /* Called on module insert or kernel boot */
 326 extern int parse_args(const char *name,
 327                       char *args,
 328                       const struct kernel_param *params,
 329                       unsigned num,
 330                       s16 level_min,
 331                       s16 level_max,
 332                       int (*unknown)(char *param, char *val,
 333                               const char *doing));
 334
 335 /* Called by module remove. */
 336 #ifdef CONFIG_SYSFS
 337 extern void destroy_params(const struct kernel_param *params, unsigned num);
 338 #else
 339 static inline void destroy_params(const struct kernel_param *params,
 340                                   unsigned num)
 341 {
 342 }
 343 #endif /* !CONFIG_SYSFS */
 344
 345 /* All the helper functions */
 346 /* The macros to do compile-time type checking stolen from Jakub
 347    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 348 #define __param_check(name, p, type) \
 349         static inline type *__check_##name(void) { return(p); }
 350
 351 extern struct kernel_param_ops param_ops_byte;
 352 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 353 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 354 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 355
 356 extern struct kernel_param_ops param_ops_short;
 357 extern int param_set_short(const char *val, const struct kernel_param *kp);
 358 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 359 #define param_check_short(name, p) __param_check(name, p, short)
 360
 361 extern struct kernel_param_ops param_ops_ushort;
 362 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 363 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 364 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 365
 366 extern struct kernel_param_ops param_ops_int;
 367 extern int param_set_int(const char *val, const struct kernel_param *kp);
 368 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 369 #define param_check_int(name, p) __param_check(name, p, int)
 370
 371 extern struct kernel_param_ops param_ops_uint;
 372 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 373 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 374 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 375
 376 extern struct kernel_param_ops param_ops_long;
 377 extern int param_set_long(const char *val, const struct kernel_param *kp);
 378 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 379 #define param_check_long(name, p) __param_check(name, p, long)
 380
 381 extern struct kernel_param_ops param_ops_ulong;
 382 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 383 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 384 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 385
 386 extern 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 #define param_check_charp(name, p) __param_check(name, p, char *)
 390
 391 /* We used to allow int as well as bool.  We're taking that away! */
 392 extern struct kernel_param_ops param_ops_bool;
 393 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 394 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 395 #define param_check_bool(name, p) __param_check(name, p, bool)
 396
 397 extern struct kernel_param_ops param_ops_invbool;
 398 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 399 extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 400 #define param_check_invbool(name, p) __param_check(name, p, bool)
 401
 402 /* An int, which can only be set like a bool (though it shows as an int). */
 403 extern struct kernel_param_ops param_ops_bint;
 404 extern int param_set_bint(const char *val, const struct kernel_param *kp);
 405 #define param_get_bint param_get_int
 406 #define param_check_bint param_check_int
 407
 408 /**
 409  * module_param_array - a parameter which is an array of some type
 410  * @name: the name of the array variable
 411  * @type: the type, as per module_param()
 412  * @nump: optional pointer filled in with the number written
 413  * @perm: visibility in sysfs
 414  *
 415  * Input and output are as comma-separated values.  Commas inside values
 416  * don't work properly (eg. an array of charp).
 417  *
 418  * ARRAY_SIZE(@name) is used to determine the number of elements in the
 419  * array, so the definition must be visible.
 420  */
 421 #define module_param_array(name, type, nump, perm)              \
 422         module_param_array_named(name, name, type, nump, perm)
 423
 424 /**
 425  * module_param_array_named - renamed parameter which is an array of some type
 426  * @name: a valid C identifier which is the parameter name
 427  * @array: the name of the array variable
 428  * @type: the type, as per module_param()
 429  * @nump: optional pointer filled in with the number written
 430  * @perm: visibility in sysfs
 431  *
 432  * This exposes a different name than the actual variable name.  See
 433  * module_param_named() for why this might be necessary.
 434  */
 435 #define module_param_array_named(name, array, type, nump, perm)         \
 436         param_check_##type(name, &(array)[0]);                          \
 437         static const struct kparam_array __param_arr_##name             \
 438         = { .max = ARRAY_SIZE(array), .num = nump,                      \
 439             .ops = &param_ops_##type,                                   \
 440             .elemsize = sizeof(array[0]), .elem = array };              \
 441         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 442                             &param_array_ops,                           \
 443                             .arr = &__param_arr_##name,                 \
 444                             perm, -1);                                  \
 445         __MODULE_PARM_TYPE(name, "array of " #type)
 446
 447 extern struct kernel_param_ops param_array_ops;
 448
 449 extern struct kernel_param_ops param_ops_string;
 450 extern int param_set_copystring(const char *val, const struct kernel_param *);
 451 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 452
 453 /* for exporting parameters in /sys/module/.../parameters */
 454
 455 struct module;
 456
 457 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 458 extern int module_param_sysfs_setup(struct module *mod,
 459                                     const struct kernel_param *kparam,
 460                                     unsigned int num_params);
 461
 462 extern void module_param_sysfs_remove(struct module *mod);
 463 #else
 464 static inline int module_param_sysfs_setup(struct module *mod,
 465                              const struct kernel_param *kparam,
 466                              unsigned int num_params)
 467 {
 468         return 0;
 469 }
 470
 471 static inline void module_param_sysfs_remove(struct module *mod)
 472 { }
 473 #endif
 474
 475 #endif /* _LINUX_MODULE_PARAMS_H */