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                                                                  \
  25   __attribute__((section(".modinfo"),unused)) = __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 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
  75    read-only sections (which is part of respective UNIX ABI on these
  76    platforms). So 'const' makes no sense and even causes compile failures
  77    with some compilers. */
  78 #if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
  79 #define __moduleparam_const
  80 #else
  81 #define __moduleparam_const const
  82 #endif
  83
  84 /* This is the fundamental function for registering boot/module
  85    parameters.  perm sets the visibility in sysfs: 000 means it's
  86    not there, read bits mean it's readable, write bits mean it's
  87    writable. */
  88 #define __module_param_call(prefix, name, ops, arg, isbool, perm)       \
  89         /* Default value instead of permissions? */                     \
  90         static int __param_perm_check_##name __attribute__((unused)) =  \
  91         BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
  92         + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
  93         static const char __param_str_##name[] = prefix #name;          \
  94         static struct kernel_param __moduleparam_const __param_##name   \
  95         __used                                                          \
  96     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
  97         = { __param_str_##name, ops, perm, isbool ? KPARAM_ISBOOL : 0,  \
  98             { arg } }
  99
 100 /* Obsolete - use module_param_cb() */
 101 #define module_param_call(name, set, get, arg, perm)                    \
 102         static struct kernel_param_ops __param_ops_##name =             \
 103                  { (void *)set, (void *)get };                          \
 104         __module_param_call(MODULE_PARAM_PREFIX,                        \
 105                             name, &__param_ops_##name, arg,             \
 106                             __same_type(*(arg), bool),                  \
 107                             (perm) + sizeof(__check_old_set_param(set))*0)
 108
 109 /* We don't get oldget: it's often a new-style param_get_uint, etc. */
 110 static inline int
 111 __check_old_set_param(int (*oldset)(const char *, struct kernel_param *))
 112 {
 113         return 0;
 114 }
 115
 116 #define module_param_cb(name, ops, arg, perm)                                 \
 117         __module_param_call(MODULE_PARAM_PREFIX,                              \
 118                             name, ops, arg, __same_type(*(arg), bool), perm)
 119
 120 /*
 121  * Helper functions: type is byte, short, ushort, int, uint, long,
 122  * ulong, charp, bool or invbool, or XXX if you define param_ops_XXX
 123  * and param_check_XXX.
 124  */
 125 #define module_param_named(name, value, type, perm)                        \
 126         param_check_##type(name, &(value));                                \
 127         module_param_cb(name, &param_ops_##type, &value, perm);            \
 128         __MODULE_PARM_TYPE(name, #type)
 129
 130 #define module_param(name, type, perm)                          \
 131         module_param_named(name, name, type, perm)
 132
 133 /**
 134  * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
 135  * @name: the name of the parameter
 136  *
 137  * There's no point blocking write on a paramter that isn't writable via sysfs!
 138  */
 139 #define kparam_block_sysfs_write(name)                  \
 140         do {                                            \
 141                 BUG_ON(!(__param_##name.perm & 0222));  \
 142                 __kernel_param_lock();                  \
 143         } while (0)
 144
 145 /**
 146  * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
 147  * @name: the name of the parameter
 148  */
 149 #define kparam_unblock_sysfs_write(name)                \
 150         do {                                            \
 151                 BUG_ON(!(__param_##name.perm & 0222));  \
 152                 __kernel_param_unlock();                \
 153         } while (0)
 154
 155 /**
 156  * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
 157  * @name: the name of the parameter
 158  *
 159  * This also blocks sysfs writes.
 160  */
 161 #define kparam_block_sysfs_read(name)                   \
 162         do {                                            \
 163                 BUG_ON(!(__param_##name.perm & 0444));  \
 164                 __kernel_param_lock();                  \
 165         } while (0)
 166
 167 /**
 168  * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
 169  * @name: the name of the parameter
 170  */
 171 #define kparam_unblock_sysfs_read(name)                 \
 172         do {                                            \
 173                 BUG_ON(!(__param_##name.perm & 0444));  \
 174                 __kernel_param_unlock();                \
 175         } while (0)
 176
 177 #ifdef CONFIG_SYSFS
 178 extern void __kernel_param_lock(void);
 179 extern void __kernel_param_unlock(void);
 180 #else
 181 static inline void __kernel_param_lock(void)
 182 {
 183 }
 184 static inline void __kernel_param_unlock(void)
 185 {
 186 }
 187 #endif
 188
 189 #ifndef MODULE
 190 /**
 191  * core_param - define a historical core kernel parameter.
 192  * @name: the name of the cmdline and sysfs parameter (often the same as var)
 193  * @var: the variable
 194  * @type: the type (for param_set_##type and param_get_##type)
 195  * @perm: visibility in sysfs
 196  *
 197  * core_param is just like module_param(), but cannot be modular and
 198  * doesn't add a prefix (such as "printk.").  This is for compatibility
 199  * with __setup(), and it makes sense as truly core parameters aren't
 200  * tied to the particular file they're in.
 201  */
 202 #define core_param(name, var, type, perm)                               \
 203         param_check_##type(name, &(var));                               \
 204         __module_param_call("", name, &param_ops_##type,                \
 205                             &var, __same_type(var, bool), perm)
 206 #endif /* !MODULE */
 207
 208 /* Actually copy string: maxlen param is usually sizeof(string). */
 209 #define module_param_string(name, string, len, perm)                    \
 210         static const struct kparam_string __param_string_##name         \
 211                 = { len, string };                                      \
 212         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 213                             &param_ops_string,                          \
 214                             .str = &__param_string_##name, 0, perm);    \
 215         __MODULE_PARM_TYPE(name, "string")
 216
 217 /* Called on module insert or kernel boot */
 218 extern int parse_args(const char *name,
 219                       char *args,
 220                       const struct kernel_param *params,
 221                       unsigned num,
 222                       int (*unknown)(char *param, char *val));
 223
 224 /* Called by module remove. */
 225 #ifdef CONFIG_SYSFS
 226 extern void destroy_params(const struct kernel_param *params, unsigned num);
 227 #else
 228 static inline void destroy_params(const struct kernel_param *params,
 229                                   unsigned num)
 230 {
 231 }
 232 #endif /* !CONFIG_SYSFS */
 233
 234 /* All the helper functions */
 235 /* The macros to do compile-time type checking stolen from Jakub
 236    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 237 #define __param_check(name, p, type) \
 238         static inline type *__check_##name(void) { return(p); }
 239
 240 extern struct kernel_param_ops param_ops_byte;
 241 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 242 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 243 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 244
 245 extern struct kernel_param_ops param_ops_short;
 246 extern int param_set_short(const char *val, const struct kernel_param *kp);
 247 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 248 #define param_check_short(name, p) __param_check(name, p, short)
 249
 250 extern struct kernel_param_ops param_ops_ushort;
 251 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 252 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 253 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 254
 255 extern struct kernel_param_ops param_ops_int;
 256 extern int param_set_int(const char *val, const struct kernel_param *kp);
 257 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 258 #define param_check_int(name, p) __param_check(name, p, int)
 259
 260 extern struct kernel_param_ops param_ops_uint;
 261 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 262 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 263 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 264
 265 extern struct kernel_param_ops param_ops_long;
 266 extern int param_set_long(const char *val, const struct kernel_param *kp);
 267 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 268 #define param_check_long(name, p) __param_check(name, p, long)
 269
 270 extern struct kernel_param_ops param_ops_ulong;
 271 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 272 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 273 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 274
 275 extern struct kernel_param_ops param_ops_charp;
 276 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 277 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 278 #define param_check_charp(name, p) __param_check(name, p, char *)
 279
 280 /* For historical reasons "bool" parameters can be (unsigned) "int". */
 281 extern struct kernel_param_ops param_ops_bool;
 282 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 283 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 284 #define param_check_bool(name, p)                                       \
 285         static inline void __check_##name(void)                         \
 286         {                                                               \
 287                 BUILD_BUG_ON(!__same_type(*(p), bool) &&                \
 288                              !__same_type(*(p), unsigned int) &&        \
 289                              !__same_type(*(p), int));                  \
 290         }
 291
 292 extern struct kernel_param_ops param_ops_invbool;
 293 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 294 extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 295 #define param_check_invbool(name, p) __param_check(name, p, bool)
 296
 297 /* Comma-separated array: *nump is set to number they actually specified. */
 298 #define module_param_array_named(name, array, type, nump, perm)         \
 299         static const struct kparam_array __param_arr_##name             \
 300         = { ARRAY_SIZE(array), nump, &param_ops_##type,                 \
 301             sizeof(array[0]), array };                                  \
 302         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 303                             &param_array_ops,                           \
 304                             .arr = &__param_arr_##name,                 \
 305                             __same_type(array[0], bool), perm);         \
 306         __MODULE_PARM_TYPE(name, "array of " #type)
 307
 308 #define module_param_array(name, type, nump, perm)              \
 309         module_param_array_named(name, name, type, nump, perm)
 310
 311 extern struct kernel_param_ops param_array_ops;
 312
 313 extern struct kernel_param_ops param_ops_string;
 314 extern int param_set_copystring(const char *val, const struct kernel_param *);
 315 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 316
 317 /* for exporting parameters in /sys/parameters */
 318
 319 struct module;
 320
 321 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 322 extern int module_param_sysfs_setup(struct module *mod,
 323                                     const struct kernel_param *kparam,
 324                                     unsigned int num_params);
 325
 326 extern void module_param_sysfs_remove(struct module *mod);
 327 #else
 328 static inline int module_param_sysfs_setup(struct module *mod,
 329                              const struct kernel_param *kparam,
 330                              unsigned int num_params)
 331 {
 332         return 0;
 333 }
 334
 335 static inline void module_param_sysfs_remove(struct module *mod)
 336 { }
 337 #endif
 338
 339 #endif /* _LINUX_MODULE_PARAMS_H */