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_cat(a,b) __mod_ ## a ## b
  21 #define __module_cat(a,b) ___module_cat(a,b)
  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 #define __MODULE_INFO(tag, name, info)
  28 #endif
  29 #define __MODULE_PARM_TYPE(name, _type)                                   \
  30   __MODULE_INFO(parmtype, name##type, #name ":" _type)
  31
  32 struct kernel_param;
  33
  34 struct kernel_param_ops {
  35         /* Returns 0, or -errno.  arg is in kp->arg. */
  36         int (*set)(const char *val, const struct kernel_param *kp);
  37         /* Returns length written or -errno.  Buffer is 4k (ie. be short!) */
  38         int (*get)(char *buffer, const struct kernel_param *kp);
  39         /* Optional function to free kp->arg when module unloaded. */
  40         void (*free)(void *arg);
  41 };
  42
  43 /* Flag bits for kernel_param.flags */
  44 #define KPARAM_ISBOOL           2
  45
  46 struct kernel_param {
  47         const char *name;
  48         const struct kernel_param_ops *ops;
  49         u16 perm;
  50         u16 flags;
  51         union {
  52                 void *arg;
  53                 const struct kparam_string *str;
  54                 const struct kparam_array *arr;
  55         };
  56 };
  57
  58 /* Special one for strings we want to copy into */
  59 struct kparam_string {
  60         unsigned int maxlen;
  61         char *string;
  62 };
  63
  64 /* Special one for arrays */
  65 struct kparam_array
  66 {
  67         unsigned int max;
  68         unsigned int *num;
  69         const struct kernel_param_ops *ops;
  70         unsigned int elemsize;
  71         void *elem;
  72 };
  73
  74 /**
  75  * module_param - typesafe helper for a module/cmdline parameter
  76  * @value: the variable to alter, and exposed parameter name.
  77  * @type: the type of the parameter
  78  * @perm: visibility in sysfs.
  79  *
  80  * @value becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
  81  * ".") the kernel commandline parameter.  Note that - is changed to _, so
  82  * the user can use "foo-bar=1" even for variable "foo_bar".
  83  *
  84  * @perm is 0 if the the variable is not to appear in sysfs, or 0444
  85  * for world-readable, 0644 for root-writable, etc.  Note that if it
  86  * is writable, you may need to use kparam_block_sysfs_write() around
  87  * accesses (esp. charp, which can be kfreed when it changes).
  88  *
  89  * The @type is simply pasted to refer to a param_ops_##type and a
  90  * param_check_##type: for convenience many standard types are provided but
  91  * you can create your own by defining those variables.
  92  *
  93  * Standard types are:
  94  *      byte, short, ushort, int, uint, long, ulong
  95  *      charp: a character pointer
  96  *      bool: a bool, values 0/1, y/n, Y/N.
  97  *      invbool: the above, only sense-reversed (N = true).
  98  */
  99 #define module_param(name, type, perm)                          \
 100         module_param_named(name, name, type, perm)
 101
 102 /**
 103  * module_param_named - typesafe helper for a renamed module/cmdline parameter
 104  * @name: a valid C identifier which is the parameter name.
 105  * @value: the actual lvalue to alter.
 106  * @type: the type of the parameter
 107  * @perm: visibility in sysfs.
 108  *
 109  * Usually it's a good idea to have variable names and user-exposed names the
 110  * same, but that's harder if the variable must be non-static or is inside a
 111  * structure.  This allows exposure under a different name.
 112  */
 113 #define module_param_named(name, value, type, perm)                        \
 114         param_check_##type(name, &(value));                                \
 115         module_param_cb(name, &param_ops_##type, &value, perm);            \
 116         __MODULE_PARM_TYPE(name, #type)
 117
 118 /**
 119  * module_param_cb - general callback for a module/cmdline parameter
 120  * @name: a valid C identifier which is the parameter name.
 121  * @ops: the set & get operations for this parameter.
 122  * @perm: visibility in sysfs.
 123  *
 124  * The ops can have NULL set or get functions.
 125  */
 126 #define module_param_cb(name, ops, arg, perm)                                 \
 127         __module_param_call(MODULE_PARAM_PREFIX,                              \
 128                             name, ops, arg, __same_type((arg), bool *), perm)
 129
 130 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
 131    read-only sections (which is part of respective UNIX ABI on these
 132    platforms). So 'const' makes no sense and even causes compile failures
 133    with some compilers. */
 134 #if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
 135 #define __moduleparam_const
 136 #else
 137 #define __moduleparam_const const
 138 #endif
 139
 140 /* This is the fundamental function for registering boot/module
 141    parameters. */
 142 #define __module_param_call(prefix, name, ops, arg, isbool, perm)       \
 143         /* Default value instead of permissions? */                     \
 144         static int __param_perm_check_##name __attribute__((unused)) =  \
 145         BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
 146         + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
 147         static const char __param_str_##name[] = prefix #name;          \
 148         static struct kernel_param __moduleparam_const __param_##name   \
 149         __used                                                          \
 150     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
 151         = { __param_str_##name, ops, perm, isbool ? KPARAM_ISBOOL : 0,  \
 152             { arg } }
 153
 154 /* Obsolete - use module_param_cb() */
 155 #define module_param_call(name, set, get, arg, perm)                    \
 156         static struct kernel_param_ops __param_ops_##name =             \
 157                  { (void *)set, (void *)get };                          \
 158         __module_param_call(MODULE_PARAM_PREFIX,                        \
 159                             name, &__param_ops_##name, arg,             \
 160                             __same_type(arg, bool *),                   \
 161                             (perm) + sizeof(__check_old_set_param(set))*0)
 162
 163 /* We don't get oldget: it's often a new-style param_get_uint, etc. */
 164 static inline int
 165 __check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 166 {
 167         return 0;
 168 }
 169
 170 /**
 171  * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
 172  * @name: the name of the parameter
 173  *
 174  * There's no point blocking write on a paramter that isn't writable via sysfs!
 175  */
 176 #define kparam_block_sysfs_write(name)                  \
 177         do {                                            \
 178                 BUG_ON(!(__param_##name.perm & 0222));  \
 179                 __kernel_param_lock();                  \
 180         } while (0)
 181
 182 /**
 183  * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
 184  * @name: the name of the parameter
 185  */
 186 #define kparam_unblock_sysfs_write(name)                \
 187         do {                                            \
 188                 BUG_ON(!(__param_##name.perm & 0222));  \
 189                 __kernel_param_unlock();                \
 190         } while (0)
 191
 192 /**
 193  * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
 194  * @name: the name of the parameter
 195  *
 196  * This also blocks sysfs writes.
 197  */
 198 #define kparam_block_sysfs_read(name)                   \
 199         do {                                            \
 200                 BUG_ON(!(__param_##name.perm & 0444));  \
 201                 __kernel_param_lock();                  \
 202         } while (0)
 203
 204 /**
 205  * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
 206  * @name: the name of the parameter
 207  */
 208 #define kparam_unblock_sysfs_read(name)                 \
 209         do {                                            \
 210                 BUG_ON(!(__param_##name.perm & 0444));  \
 211                 __kernel_param_unlock();                \
 212         } while (0)
 213
 214 #ifdef CONFIG_SYSFS
 215 extern void __kernel_param_lock(void);
 216 extern void __kernel_param_unlock(void);
 217 #else
 218 static inline void __kernel_param_lock(void)
 219 {
 220 }
 221 static inline void __kernel_param_unlock(void)
 222 {
 223 }
 224 #endif
 225
 226 #ifndef MODULE
 227 /**
 228  * core_param - define a historical core kernel parameter.
 229  * @name: the name of the cmdline and sysfs parameter (often the same as var)
 230  * @var: the variable
 231  * @type: the type of the parameter
 232  * @perm: visibility in sysfs
 233  *
 234  * core_param is just like module_param(), but cannot be modular and
 235  * doesn't add a prefix (such as "printk.").  This is for compatibility
 236  * with __setup(), and it makes sense as truly core parameters aren't
 237  * tied to the particular file they're in.
 238  */
 239 #define core_param(name, var, type, perm)                               \
 240         param_check_##type(name, &(var));                               \
 241         __module_param_call("", name, &param_ops_##type,                \
 242                             &var, __same_type(var, bool), perm)
 243 #endif /* !MODULE */
 244
 245 /**
 246  * module_param_string - a char array parameter
 247  * @name: the name of the parameter
 248  * @string: the string variable
 249  * @len: the maximum length of the string, incl. terminator
 250  * @perm: visibility in sysfs.
 251  *
 252  * This actually copies the string when it's set (unlike type charp).
 253  * @len is usually just sizeof(string).
 254  */
 255 #define module_param_string(name, string, len, perm)                    \
 256         static const struct kparam_string __param_string_##name         \
 257                 = { len, string };                                      \
 258         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 259                             &param_ops_string,                          \
 260                             .str = &__param_string_##name, 0, perm);    \
 261         __MODULE_PARM_TYPE(name, "string")
 262
 263 /* Called on module insert or kernel boot */
 264 extern int parse_args(const char *name,
 265                       char *args,
 266                       const struct kernel_param *params,
 267                       unsigned num,
 268                       int (*unknown)(char *param, char *val));
 269
 270 /* Called by module remove. */
 271 #ifdef CONFIG_SYSFS
 272 extern void destroy_params(const struct kernel_param *params, unsigned num);
 273 #else
 274 static inline void destroy_params(const struct kernel_param *params,
 275                                   unsigned num)
 276 {
 277 }
 278 #endif /* !CONFIG_SYSFS */
 279
 280 /* All the helper functions */
 281 /* The macros to do compile-time type checking stolen from Jakub
 282    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 283 #define __param_check(name, p, type) \
 284         static inline type *__check_##name(void) { return(p); }
 285
 286 extern struct kernel_param_ops param_ops_byte;
 287 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 288 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 289 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 290
 291 extern struct kernel_param_ops param_ops_short;
 292 extern int param_set_short(const char *val, const struct kernel_param *kp);
 293 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 294 #define param_check_short(name, p) __param_check(name, p, short)
 295
 296 extern struct kernel_param_ops param_ops_ushort;
 297 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 298 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 299 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 300
 301 extern struct kernel_param_ops param_ops_int;
 302 extern int param_set_int(const char *val, const struct kernel_param *kp);
 303 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 304 #define param_check_int(name, p) __param_check(name, p, int)
 305
 306 extern struct kernel_param_ops param_ops_uint;
 307 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 308 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 309 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 310
 311 extern struct kernel_param_ops param_ops_long;
 312 extern int param_set_long(const char *val, const struct kernel_param *kp);
 313 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 314 #define param_check_long(name, p) __param_check(name, p, long)
 315
 316 extern struct kernel_param_ops param_ops_ulong;
 317 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 318 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 319 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 320
 321 extern struct kernel_param_ops param_ops_charp;
 322 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 323 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 324 #define param_check_charp(name, p) __param_check(name, p, char *)
 325
 326 /* For historical reasons "bool" parameters can be (unsigned) "int". */
 327 extern struct kernel_param_ops param_ops_bool;
 328 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 329 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 330 #define param_check_bool(name, p)                                       \
 331         static inline void __check_##name(void)                         \
 332         {                                                               \
 333                 BUILD_BUG_ON(!__same_type((p), bool *) &&               \
 334                              !__same_type((p), unsigned int *) &&       \
 335                              !__same_type((p), int *));                 \
 336         }
 337
 338 extern struct kernel_param_ops param_ops_invbool;
 339 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 340 extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 341 #define param_check_invbool(name, p) __param_check(name, p, bool)
 342
 343 /**
 344  * module_param_array - a parameter which is an array of some type
 345  * @name: the name of the array variable
 346  * @type: the type, as per module_param()
 347  * @nump: optional pointer filled in with the number written
 348  * @perm: visibility in sysfs
 349  *
 350  * Input and output are as comma-separated values.  Commas inside values
 351  * don't work properly (eg. an array of charp).
 352  *
 353  * ARRAY_SIZE(@name) is used to determine the number of elements in the
 354  * array, so the definition must be visible.
 355  */
 356 #define module_param_array(name, type, nump, perm)              \
 357         module_param_array_named(name, name, type, nump, perm)
 358
 359 /**
 360  * module_param_array_named - renamed parameter which is an array of some type
 361  * @name: a valid C identifier which is the parameter name
 362  * @array: the name of the array variable
 363  * @type: the type, as per module_param()
 364  * @nump: optional pointer filled in with the number written
 365  * @perm: visibility in sysfs
 366  *
 367  * This exposes a different name than the actual variable name.  See
 368  * module_param_named() for why this might be necessary.
 369  */
 370 #define module_param_array_named(name, array, type, nump, perm)         \
 371         static const struct kparam_array __param_arr_##name             \
 372         = { ARRAY_SIZE(array), nump, &param_ops_##type,                 \
 373             sizeof(array[0]), array };                                  \
 374         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 375                             &param_array_ops,                           \
 376                             .arr = &__param_arr_##name,                 \
 377                             __same_type(array[0], bool), perm);         \
 378         __MODULE_PARM_TYPE(name, "array of " #type)
 379
 380 extern struct kernel_param_ops param_array_ops;
 381
 382 extern struct kernel_param_ops param_ops_string;
 383 extern int param_set_copystring(const char *val, const struct kernel_param *);
 384 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 385
 386 /* for exporting parameters in /sys/parameters */
 387
 388 struct module;
 389
 390 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 391 extern int module_param_sysfs_setup(struct module *mod,
 392                                     const struct kernel_param *kparam,
 393                                     unsigned int num_params);
 394
 395 extern void module_param_sysfs_remove(struct module *mod);
 396 #else
 397 static inline int module_param_sysfs_setup(struct module *mod,
 398                              const struct kernel_param *kparam,
 399                              unsigned int num_params)
 400 {
 401         return 0;
 402 }
 403
 404 static inline void module_param_sysfs_remove(struct module *mod)
 405 { }
 406 #endif
 407
 408 #endif /* _LINUX_MODULE_PARAMS_H */