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 struct kernel_param;
  35
  36 struct kernel_param_ops {
  37         /* Returns 0, or -errno.  arg is in kp->arg. */
  38         int (*set)(const char *val, const struct kernel_param *kp);
  39         /* Returns length written or -errno.  Buffer is 4k (ie. be short!) */
  40         int (*get)(char *buffer, const struct kernel_param *kp);
  41         /* Optional function to free kp->arg when module unloaded. */
  42         void (*free)(void *arg);
  43 };
  44
  45 /* Flag bits for kernel_param.flags */
  46 #define KPARAM_ISBOOL           2
  47
  48 struct kernel_param {
  49         const char *name;
  50         const struct kernel_param_ops *ops;
  51         u16 perm;
  52         u16 flags;
  53         union {
  54                 void *arg;
  55                 const struct kparam_string *str;
  56                 const struct kparam_array *arr;
  57         };
  58 };
  59
  60 /* Special one for strings we want to copy into */
  61 struct kparam_string {
  62         unsigned int maxlen;
  63         char *string;
  64 };
  65
  66 /* Special one for arrays */
  67 struct kparam_array
  68 {
  69         unsigned int max;
  70         unsigned int elemsize;
  71         unsigned int *num;
  72         const struct kernel_param_ops *ops;
  73         void *elem;
  74 };
  75
  76 /**
  77  * module_param - typesafe helper for a module/cmdline parameter
  78  * @value: the variable to alter, and exposed parameter name.
  79  * @type: the type of the parameter
  80  * @perm: visibility in sysfs.
  81  *
  82  * @value becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
  83  * ".") the kernel commandline parameter.  Note that - is changed to _, so
  84  * the user can use "foo-bar=1" even for variable "foo_bar".
  85  *
  86  * @perm is 0 if the the variable is not to appear in sysfs, or 0444
  87  * for world-readable, 0644 for root-writable, etc.  Note that if it
  88  * is writable, you may need to use kparam_block_sysfs_write() around
  89  * accesses (esp. charp, which can be kfreed when it changes).
  90  *
  91  * The @type is simply pasted to refer to a param_ops_##type and a
  92  * param_check_##type: for convenience many standard types are provided but
  93  * you can create your own by defining those variables.
  94  *
  95  * Standard types are:
  96  *      byte, short, ushort, int, uint, long, ulong
  97  *      charp: a character pointer
  98  *      bool: a bool, values 0/1, y/n, Y/N.
  99  *      invbool: the above, only sense-reversed (N = true).
 100  */
 101 #define module_param(name, type, perm)                          \
 102         module_param_named(name, name, type, perm)
 103
 104 /**
 105  * module_param_named - typesafe helper for a renamed module/cmdline parameter
 106  * @name: a valid C identifier which is the parameter name.
 107  * @value: the actual lvalue to alter.
 108  * @type: the type of the parameter
 109  * @perm: visibility in sysfs.
 110  *
 111  * Usually it's a good idea to have variable names and user-exposed names the
 112  * same, but that's harder if the variable must be non-static or is inside a
 113  * structure.  This allows exposure under a different name.
 114  */
 115 #define module_param_named(name, value, type, perm)                        \
 116         param_check_##type(name, &(value));                                \
 117         module_param_cb(name, &param_ops_##type, &value, perm);            \
 118         __MODULE_PARM_TYPE(name, #type)
 119
 120 /**
 121  * module_param_cb - general callback for a module/cmdline parameter
 122  * @name: a valid C identifier which is the parameter name.
 123  * @ops: the set & get operations for this parameter.
 124  * @perm: visibility in sysfs.
 125  *
 126  * The ops can have NULL set or get functions.
 127  */
 128 #define module_param_cb(name, ops, arg, perm)                                 \
 129         __module_param_call(MODULE_PARAM_PREFIX,                              \
 130                             name, ops, arg, __same_type((arg), bool *), perm)
 131
 132 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
 133    read-only sections (which is part of respective UNIX ABI on these
 134    platforms). So 'const' makes no sense and even causes compile failures
 135    with some compilers. */
 136 #if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
 137 #define __moduleparam_const
 138 #else
 139 #define __moduleparam_const const
 140 #endif
 141
 142 /* This is the fundamental function for registering boot/module
 143    parameters. */
 144 #define __module_param_call(prefix, name, ops, arg, isbool, perm)       \
 145         /* Default value instead of permissions? */                     \
 146         static int __param_perm_check_##name __attribute__((unused)) =  \
 147         BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
 148         + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
 149         static const char __param_str_##name[] = prefix #name;          \
 150         static struct kernel_param __moduleparam_const __param_##name   \
 151         __used                                                          \
 152     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
 153         = { __param_str_##name, ops, perm, isbool ? KPARAM_ISBOOL : 0,  \
 154             { arg } }
 155
 156 /* Obsolete - use module_param_cb() */
 157 #define module_param_call(name, set, get, arg, perm)                    \
 158         static struct kernel_param_ops __param_ops_##name =             \
 159                  { (void *)set, (void *)get };                          \
 160         __module_param_call(MODULE_PARAM_PREFIX,                        \
 161                             name, &__param_ops_##name, arg,             \
 162                             __same_type(arg, bool *),                   \
 163                             (perm) + sizeof(__check_old_set_param(set))*0)
 164
 165 /* We don't get oldget: it's often a new-style param_get_uint, etc. */
 166 static inline int
 167 __check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 168 {
 169         return 0;
 170 }
 171
 172 /**
 173  * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
 174  * @name: the name of the parameter
 175  *
 176  * There's no point blocking write on a paramter that isn't writable via sysfs!
 177  */
 178 #define kparam_block_sysfs_write(name)                  \
 179         do {                                            \
 180                 BUG_ON(!(__param_##name.perm & 0222));  \
 181                 __kernel_param_lock();                  \
 182         } while (0)
 183
 184 /**
 185  * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
 186  * @name: the name of the parameter
 187  */
 188 #define kparam_unblock_sysfs_write(name)                \
 189         do {                                            \
 190                 BUG_ON(!(__param_##name.perm & 0222));  \
 191                 __kernel_param_unlock();                \
 192         } while (0)
 193
 194 /**
 195  * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
 196  * @name: the name of the parameter
 197  *
 198  * This also blocks sysfs writes.
 199  */
 200 #define kparam_block_sysfs_read(name)                   \
 201         do {                                            \
 202                 BUG_ON(!(__param_##name.perm & 0444));  \
 203                 __kernel_param_lock();                  \
 204         } while (0)
 205
 206 /**
 207  * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
 208  * @name: the name of the parameter
 209  */
 210 #define kparam_unblock_sysfs_read(name)                 \
 211         do {                                            \
 212                 BUG_ON(!(__param_##name.perm & 0444));  \
 213                 __kernel_param_unlock();                \
 214         } while (0)
 215
 216 #ifdef CONFIG_SYSFS
 217 extern void __kernel_param_lock(void);
 218 extern void __kernel_param_unlock(void);
 219 #else
 220 static inline void __kernel_param_lock(void)
 221 {
 222 }
 223 static inline void __kernel_param_unlock(void)
 224 {
 225 }
 226 #endif
 227
 228 #ifndef MODULE
 229 /**
 230  * core_param - define a historical core kernel parameter.
 231  * @name: the name of the cmdline and sysfs parameter (often the same as var)
 232  * @var: the variable
 233  * @type: the type of the parameter
 234  * @perm: visibility in sysfs
 235  *
 236  * core_param is just like module_param(), but cannot be modular and
 237  * doesn't add a prefix (such as "printk.").  This is for compatibility
 238  * with __setup(), and it makes sense as truly core parameters aren't
 239  * tied to the particular file they're in.
 240  */
 241 #define core_param(name, var, type, perm)                               \
 242         param_check_##type(name, &(var));                               \
 243         __module_param_call("", name, &param_ops_##type,                \
 244                             &var, __same_type(var, bool), perm)
 245 #endif /* !MODULE */
 246
 247 /**
 248  * module_param_string - a char array parameter
 249  * @name: the name of the parameter
 250  * @string: the string variable
 251  * @len: the maximum length of the string, incl. terminator
 252  * @perm: visibility in sysfs.
 253  *
 254  * This actually copies the string when it's set (unlike type charp).
 255  * @len is usually just sizeof(string).
 256  */
 257 #define module_param_string(name, string, len, perm)                    \
 258         static const struct kparam_string __param_string_##name         \
 259                 = { len, string };                                      \
 260         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 261                             &param_ops_string,                          \
 262                             .str = &__param_string_##name, 0, perm);    \
 263         __MODULE_PARM_TYPE(name, "string")
 264
 265 /* Called on module insert or kernel boot */
 266 extern int parse_args(const char *name,
 267                       char *args,
 268                       const struct kernel_param *params,
 269                       unsigned num,
 270                       int (*unknown)(char *param, char *val));
 271
 272 /* Called by module remove. */
 273 #ifdef CONFIG_SYSFS
 274 extern void destroy_params(const struct kernel_param *params, unsigned num);
 275 #else
 276 static inline void destroy_params(const struct kernel_param *params,
 277                                   unsigned num)
 278 {
 279 }
 280 #endif /* !CONFIG_SYSFS */
 281
 282 /* All the helper functions */
 283 /* The macros to do compile-time type checking stolen from Jakub
 284    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 285 #define __param_check(name, p, type) \
 286         static inline type *__check_##name(void) { return(p); }
 287
 288 extern struct kernel_param_ops param_ops_byte;
 289 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 290 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 291 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 292
 293 extern struct kernel_param_ops param_ops_short;
 294 extern int param_set_short(const char *val, const struct kernel_param *kp);
 295 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 296 #define param_check_short(name, p) __param_check(name, p, short)
 297
 298 extern struct kernel_param_ops param_ops_ushort;
 299 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 300 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 301 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 302
 303 extern struct kernel_param_ops param_ops_int;
 304 extern int param_set_int(const char *val, const struct kernel_param *kp);
 305 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 306 #define param_check_int(name, p) __param_check(name, p, int)
 307
 308 extern struct kernel_param_ops param_ops_uint;
 309 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 310 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 311 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 312
 313 extern struct kernel_param_ops param_ops_long;
 314 extern int param_set_long(const char *val, const struct kernel_param *kp);
 315 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 316 #define param_check_long(name, p) __param_check(name, p, long)
 317
 318 extern struct kernel_param_ops param_ops_ulong;
 319 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 320 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 321 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 322
 323 extern struct kernel_param_ops param_ops_charp;
 324 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 325 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 326 #define param_check_charp(name, p) __param_check(name, p, char *)
 327
 328 /* For historical reasons "bool" parameters can be (unsigned) "int". */
 329 extern struct kernel_param_ops param_ops_bool;
 330 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 331 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 332 #define param_check_bool(name, p)                                       \
 333         static inline void __check_##name(void)                         \
 334         {                                                               \
 335                 BUILD_BUG_ON(!__same_type((p), bool *) &&               \
 336                              !__same_type((p), unsigned int *) &&       \
 337                              !__same_type((p), int *));                 \
 338         }
 339
 340 extern struct kernel_param_ops param_ops_invbool;
 341 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 342 extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 343 #define param_check_invbool(name, p) __param_check(name, p, bool)
 344
 345 /**
 346  * module_param_array - a parameter which is an array of some type
 347  * @name: the name of the array variable
 348  * @type: the type, as per module_param()
 349  * @nump: optional pointer filled in with the number written
 350  * @perm: visibility in sysfs
 351  *
 352  * Input and output are as comma-separated values.  Commas inside values
 353  * don't work properly (eg. an array of charp).
 354  *
 355  * ARRAY_SIZE(@name) is used to determine the number of elements in the
 356  * array, so the definition must be visible.
 357  */
 358 #define module_param_array(name, type, nump, perm)              \
 359         module_param_array_named(name, name, type, nump, perm)
 360
 361 /**
 362  * module_param_array_named - renamed parameter which is an array of some type
 363  * @name: a valid C identifier which is the parameter name
 364  * @array: the name of the array variable
 365  * @type: the type, as per module_param()
 366  * @nump: optional pointer filled in with the number written
 367  * @perm: visibility in sysfs
 368  *
 369  * This exposes a different name than the actual variable name.  See
 370  * module_param_named() for why this might be necessary.
 371  */
 372 #define module_param_array_named(name, array, type, nump, perm)         \
 373         static const struct kparam_array __param_arr_##name             \
 374         = { .max = ARRAY_SIZE(array), .num = nump,                      \
 375             .ops = &param_ops_##type,                                   \
 376             .elemsize = sizeof(array[0]), .elem = array };              \
 377         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 378                             &param_array_ops,                           \
 379                             .arr = &__param_arr_##name,                 \
 380                             __same_type(array[0], bool), perm);         \
 381         __MODULE_PARM_TYPE(name, "array of " #type)
 382
 383 extern struct kernel_param_ops param_array_ops;
 384
 385 extern struct kernel_param_ops param_ops_string;
 386 extern int param_set_copystring(const char *val, const struct kernel_param *);
 387 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 388
 389 /* for exporting parameters in /sys/parameters */
 390
 391 struct module;
 392
 393 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 394 extern int module_param_sysfs_setup(struct module *mod,
 395                                     const struct kernel_param *kparam,
 396                                     unsigned int num_params);
 397
 398 extern void module_param_sysfs_remove(struct module *mod);
 399 #else
 400 static inline int module_param_sysfs_setup(struct module *mod,
 401                              const struct kernel_param *kparam,
 402                              unsigned int num_params)
 403 {
 404         return 0;
 405 }
 406
 407 static inline void module_param_sysfs_remove(struct module *mod)
 408 { }
 409 #endif
 410
 411 #endif /* _LINUX_MODULE_PARAMS_H */