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 #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)                                    \
  23 static 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
  39 struct kernel_param;
  40
  41 struct 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
  50 /* Flag bits for kernel_param.flags */
  51 #define KPARAM_ISBOOL           2
  52
  53 struct kernel_param {
  54         const char *name;
  55         const struct kernel_param_ops *ops;
  56         u16 perm;
  57         u16 flags;
  58         union {
  59                 void *arg;
  60                 const struct kparam_string *str;
  61                 const struct kparam_array *arr;
  62         };
  63 };
  64
  65 /* Special one for strings we want to copy into */
  66 struct kparam_string {
  67         unsigned int maxlen;
  68         char *string;
  69 };
  70
  71 /* Special one for arrays */
  72 struct kparam_array
  73 {
  74         unsigned int max;
  75         unsigned int elemsize;
  76         unsigned int *num;
  77         const struct kernel_param_ops *ops;
  78         void *elem;
  79 };
  80
  81 /**
  82  * module_param - typesafe helper for a module/cmdline parameter
  83  * @value: the variable to alter, and exposed parameter name.
  84  * @type: the type of the parameter
  85  * @perm: visibility in sysfs.
  86  *
  87  * @value becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
  88  * ".") the kernel commandline parameter.  Note that - is changed to _, so
  89  * the user can use "foo-bar=1" even for variable "foo_bar".
  90  *
  91  * @perm is 0 if the the variable is not to appear in sysfs, or 0444
  92  * for world-readable, 0644 for root-writable, etc.  Note that if it
  93  * is writable, you may need to use kparam_block_sysfs_write() around
  94  * accesses (esp. charp, which can be kfreed when it changes).
  95  *
  96  * The @type is simply pasted to refer to a param_ops_##type and a
  97  * param_check_##type: for convenience many standard types are provided but
  98  * you can create your own by defining those variables.
  99  *
 100  * Standard types are:
 101  *      byte, short, ushort, int, uint, long, ulong
 102  *      charp: a character pointer
 103  *      bool: a bool, values 0/1, y/n, Y/N.
 104  *      invbool: the above, only sense-reversed (N = true).
 105  */
 106 #define module_param(name, type, perm)                          \
 107         module_param_named(name, name, type, perm)
 108
 109 /**
 110  * module_param_named - typesafe helper for a renamed module/cmdline parameter
 111  * @name: a valid C identifier which is the parameter name.
 112  * @value: the actual lvalue to alter.
 113  * @type: the type of the parameter
 114  * @perm: visibility in sysfs.
 115  *
 116  * Usually it's a good idea to have variable names and user-exposed names the
 117  * same, but that's harder if the variable must be non-static or is inside a
 118  * structure.  This allows exposure under a different name.
 119  */
 120 #define module_param_named(name, value, type, perm)                        \
 121         param_check_##type(name, &(value));                                \
 122         module_param_cb(name, &param_ops_##type, &value, perm);            \
 123         __MODULE_PARM_TYPE(name, #type)
 124
 125 /**
 126  * module_param_cb - general callback for a module/cmdline parameter
 127  * @name: a valid C identifier which is the parameter name.
 128  * @ops: the set & get operations for this parameter.
 129  * @perm: visibility in sysfs.
 130  *
 131  * The ops can have NULL set or get functions.
 132  */
 133 #define module_param_cb(name, ops, arg, perm)                                 \
 134         __module_param_call(MODULE_PARAM_PREFIX,                              \
 135                             name, ops, arg, __same_type((arg), bool *), perm)
 136
 137 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
 138    read-only sections (which is part of respective UNIX ABI on these
 139    platforms). So 'const' makes no sense and even causes compile failures
 140    with some compilers. */
 141 #if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
 142 #define __moduleparam_const
 143 #else
 144 #define __moduleparam_const const
 145 #endif
 146
 147 /* This is the fundamental function for registering boot/module
 148    parameters. */
 149 #define __module_param_call(prefix, name, ops, arg, isbool, perm)       \
 150         /* Default value instead of permissions? */                     \
 151         static int __param_perm_check_##name __attribute__((unused)) =  \
 152         BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
 153         + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
 154         static const char __param_str_##name[] = prefix #name;          \
 155         static struct kernel_param __moduleparam_const __param_##name   \
 156         __used                                                          \
 157     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
 158         = { __param_str_##name, ops, perm, isbool ? KPARAM_ISBOOL : 0,  \
 159             { arg } }
 160
 161 /* Obsolete - use module_param_cb() */
 162 #define module_param_call(name, set, get, arg, perm)                    \
 163         static struct kernel_param_ops __param_ops_##name =             \
 164                  { (void *)set, (void *)get };                          \
 165         __module_param_call(MODULE_PARAM_PREFIX,                        \
 166                             name, &__param_ops_##name, arg,             \
 167                             __same_type(arg, bool *),                   \
 168                             (perm) + sizeof(__check_old_set_param(set))*0)
 169
 170 /* We don't get oldget: it's often a new-style param_get_uint, etc. */
 171 static inline int
 172 __check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 173 {
 174         return 0;
 175 }
 176
 177 /**
 178  * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
 179  * @name: the name of the parameter
 180  *
 181  * There's no point blocking write on a paramter that isn't writable via sysfs!
 182  */
 183 #define kparam_block_sysfs_write(name)                  \
 184         do {                                            \
 185                 BUG_ON(!(__param_##name.perm & 0222));  \
 186                 __kernel_param_lock();                  \
 187         } while (0)
 188
 189 /**
 190  * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
 191  * @name: the name of the parameter
 192  */
 193 #define kparam_unblock_sysfs_write(name)                \
 194         do {                                            \
 195                 BUG_ON(!(__param_##name.perm & 0222));  \
 196                 __kernel_param_unlock();                \
 197         } while (0)
 198
 199 /**
 200  * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
 201  * @name: the name of the parameter
 202  *
 203  * This also blocks sysfs writes.
 204  */
 205 #define kparam_block_sysfs_read(name)                   \
 206         do {                                            \
 207                 BUG_ON(!(__param_##name.perm & 0444));  \
 208                 __kernel_param_lock();                  \
 209         } while (0)
 210
 211 /**
 212  * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
 213  * @name: the name of the parameter
 214  */
 215 #define kparam_unblock_sysfs_read(name)                 \
 216         do {                                            \
 217                 BUG_ON(!(__param_##name.perm & 0444));  \
 218                 __kernel_param_unlock();                \
 219         } while (0)
 220
 221 #ifdef CONFIG_SYSFS
 222 extern void __kernel_param_lock(void);
 223 extern void __kernel_param_unlock(void);
 224 #else
 225 static inline void __kernel_param_lock(void)
 226 {
 227 }
 228 static inline void __kernel_param_unlock(void)
 229 {
 230 }
 231 #endif
 232
 233 #ifndef MODULE
 234 /**
 235  * core_param - define a historical core kernel parameter.
 236  * @name: the name of the cmdline and sysfs parameter (often the same as var)
 237  * @var: the variable
 238  * @type: the type of the parameter
 239  * @perm: visibility in sysfs
 240  *
 241  * core_param is just like module_param(), but cannot be modular and
 242  * doesn't add a prefix (such as "printk.").  This is for compatibility
 243  * with __setup(), and it makes sense as truly core parameters aren't
 244  * tied to the particular file they're in.
 245  */
 246 #define core_param(name, var, type, perm)                               \
 247         param_check_##type(name, &(var));                               \
 248         __module_param_call("", name, &param_ops_##type,                \
 249                             &var, __same_type(var, bool), perm)
 250 #endif /* !MODULE */
 251
 252 /**
 253  * module_param_string - a char array parameter
 254  * @name: the name of the parameter
 255  * @string: the string variable
 256  * @len: the maximum length of the string, incl. terminator
 257  * @perm: visibility in sysfs.
 258  *
 259  * This actually copies the string when it's set (unlike type charp).
 260  * @len is usually just sizeof(string).
 261  */
 262 #define module_param_string(name, string, len, perm)                    \
 263         static const struct kparam_string __param_string_##name         \
 264                 = { len, string };                                      \
 265         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 266                             &param_ops_string,                          \
 267                             .str = &__param_string_##name, 0, perm);    \
 268         __MODULE_PARM_TYPE(name, "string")
 269
 270 /**
 271  * parameq - checks if two parameter names match
 272  * @name1: parameter name 1
 273  * @name2: parameter name 2
 274  *
 275  * Returns true if the two parameter names are equal.
 276  * Dashes (-) are considered equal to underscores (_).
 277  */
 278 extern bool parameq(const char *name1, const char *name2);
 279
 280 /**
 281  * parameqn - checks if two parameter names match
 282  * @name1: parameter name 1
 283  * @name2: parameter name 2
 284  * @n: the length to compare
 285  *
 286  * Similar to parameq(), except it compares @n characters.
 287  */
 288 extern bool parameqn(const char *name1, const char *name2, size_t n);
 289
 290 /* Called on module insert or kernel boot */
 291 extern int parse_args(const char *name,
 292                       char *args,
 293                       const struct kernel_param *params,
 294                       unsigned num,
 295                       int (*unknown)(char *param, char *val));
 296
 297 /* Called by module remove. */
 298 #ifdef CONFIG_SYSFS
 299 extern void destroy_params(const struct kernel_param *params, unsigned num);
 300 #else
 301 static inline void destroy_params(const struct kernel_param *params,
 302                                   unsigned num)
 303 {
 304 }
 305 #endif /* !CONFIG_SYSFS */
 306
 307 /* All the helper functions */
 308 /* The macros to do compile-time type checking stolen from Jakub
 309    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 310 #define __param_check(name, p, type) \
 311         static inline type *__check_##name(void) { return(p); }
 312
 313 extern struct kernel_param_ops param_ops_byte;
 314 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 315 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 316 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 317
 318 extern struct kernel_param_ops param_ops_short;
 319 extern int param_set_short(const char *val, const struct kernel_param *kp);
 320 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 321 #define param_check_short(name, p) __param_check(name, p, short)
 322
 323 extern struct kernel_param_ops param_ops_ushort;
 324 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 325 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 326 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 327
 328 extern struct kernel_param_ops param_ops_int;
 329 extern int param_set_int(const char *val, const struct kernel_param *kp);
 330 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 331 #define param_check_int(name, p) __param_check(name, p, int)
 332
 333 extern struct kernel_param_ops param_ops_uint;
 334 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 335 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 336 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 337
 338 extern struct kernel_param_ops param_ops_long;
 339 extern int param_set_long(const char *val, const struct kernel_param *kp);
 340 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 341 #define param_check_long(name, p) __param_check(name, p, long)
 342
 343 extern struct kernel_param_ops param_ops_ulong;
 344 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 345 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 346 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 347
 348 extern struct kernel_param_ops param_ops_charp;
 349 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 350 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 351 #define param_check_charp(name, p) __param_check(name, p, char *)
 352
 353 /* For historical reasons "bool" parameters can be (unsigned) "int". */
 354 extern struct kernel_param_ops param_ops_bool;
 355 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 356 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 357 #define param_check_bool(name, p)                                       \
 358         static inline void __check_##name(void)                         \
 359         {                                                               \
 360                 BUILD_BUG_ON(!__same_type((p), bool *) &&               \
 361                              !__same_type((p), unsigned int *) &&       \
 362                              !__same_type((p), int *));                 \
 363         }
 364
 365 extern struct kernel_param_ops param_ops_invbool;
 366 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 367 extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 368 #define param_check_invbool(name, p) __param_check(name, p, bool)
 369
 370 /**
 371  * module_param_array - a parameter which is an array of some type
 372  * @name: the name of the array variable
 373  * @type: the type, as per module_param()
 374  * @nump: optional pointer filled in with the number written
 375  * @perm: visibility in sysfs
 376  *
 377  * Input and output are as comma-separated values.  Commas inside values
 378  * don't work properly (eg. an array of charp).
 379  *
 380  * ARRAY_SIZE(@name) is used to determine the number of elements in the
 381  * array, so the definition must be visible.
 382  */
 383 #define module_param_array(name, type, nump, perm)              \
 384         module_param_array_named(name, name, type, nump, perm)
 385
 386 /**
 387  * module_param_array_named - renamed parameter which is an array of some type
 388  * @name: a valid C identifier which is the parameter name
 389  * @array: the name of the array variable
 390  * @type: the type, as per module_param()
 391  * @nump: optional pointer filled in with the number written
 392  * @perm: visibility in sysfs
 393  *
 394  * This exposes a different name than the actual variable name.  See
 395  * module_param_named() for why this might be necessary.
 396  */
 397 #define module_param_array_named(name, array, type, nump, perm)         \
 398         static const struct kparam_array __param_arr_##name             \
 399         = { .max = ARRAY_SIZE(array), .num = nump,                      \
 400             .ops = &param_ops_##type,                                   \
 401             .elemsize = sizeof(array[0]), .elem = array };              \
 402         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 403                             &param_array_ops,                           \
 404                             .arr = &__param_arr_##name,                 \
 405                             __same_type(array[0], bool), perm);         \
 406         __MODULE_PARM_TYPE(name, "array of " #type)
 407
 408 extern struct kernel_param_ops param_array_ops;
 409
 410 extern struct kernel_param_ops param_ops_string;
 411 extern int param_set_copystring(const char *val, const struct kernel_param *);
 412 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 413
 414 /* for exporting parameters in /sys/parameters */
 415
 416 struct module;
 417
 418 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 419 extern int module_param_sysfs_setup(struct module *mod,
 420                                     const struct kernel_param *kparam,
 421                                     unsigned int num_params);
 422
 423 extern void module_param_sysfs_remove(struct module *mod);
 424 #else
 425 static inline int module_param_sysfs_setup(struct module *mod,
 426                              const struct kernel_param *kparam,
 427                              unsigned int num_params)
 428 {
 429         return 0;
 430 }
 431
 432 static inline void module_param_sysfs_remove(struct module *mod)
 433 { }
 434 #endif
 435
 436 #endif /* _LINUX_MODULE_PARAMS_H */