include/linux/moduleparam.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_MODULE_PARAMS_H
   3 #define _LINUX_MODULE_PARAMS_H
   4 /* (C) Copyright 2001, 2002 Rusty Russell IBM Corporation */
   5 #include <linux/init.h>
   6 #include <linux/stringify.h>
   7 #include <linux/kernel.h>
   8
   9 /* You can override this manually, but generally this should match the
  10    module name. */
  11 #ifdef MODULE
  12 #define MODULE_PARAM_PREFIX /* empty */
  13 #define __MODULE_INFO_PREFIX /* empty */
  14 #else
  15 #define MODULE_PARAM_PREFIX KBUILD_MODNAME "."
  16 /* We cannot use MODULE_PARAM_PREFIX because some modules override it. */
  17 #define __MODULE_INFO_PREFIX KBUILD_MODNAME "."
  18 #endif
  19
  20 /* Chosen so that structs with an unsigned long line up. */
  21 #define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
  22
  23 #define __MODULE_INFO(tag, name, info)                                    \
  24 static const char __UNIQUE_ID(name)[]                                     \
  25   __used __attribute__((section(".modinfo"), unused, aligned(1)))         \
  26   = __MODULE_INFO_PREFIX __stringify(tag) "=" info
  27
  28 #define __MODULE_PARM_TYPE(name, _type)                                   \
  29   __MODULE_INFO(parmtype, name##type, #name ":" _type)
  30
  31 /* One for each parameter, describing how to use it.  Some files do
  32    multiple of these per line, so can't just use MODULE_INFO. */
  33 #define MODULE_PARM_DESC(_parm, desc) \
  34         __MODULE_INFO(parm, _parm, #_parm ":" desc)
  35
  36 struct kernel_param;
  37
  38 /*
  39  * Flags available for kernel_param_ops
  40  *
  41  * NOARG - the parameter allows for no argument (foo instead of foo=1)
  42  */
  43 enum {
  44         KERNEL_PARAM_OPS_FL_NOARG = (1 << 0)
  45 };
  46
  47 struct kernel_param_ops {
  48         /* How the ops should behave */
  49         unsigned int flags;
  50         /* Returns 0, or -errno.  arg is in kp->arg. */
  51         int (*set)(const char *val, const struct kernel_param *kp);
  52         /* Returns length written or -errno.  Buffer is 4k (ie. be short!) */
  53         int (*get)(char *buffer, const struct kernel_param *kp);
  54         /* Optional function to free kp->arg when module unloaded. */
  55         void (*free)(void *arg);
  56 };
  57
  58 /*
  59  * Flags available for kernel_param
  60  *
  61  * UNSAFE - the parameter is dangerous and setting it will taint the kernel
  62  * HWPARAM - Hardware param not permitted in lockdown mode
  63  */
  64 enum {
  65         KERNEL_PARAM_FL_UNSAFE  = (1 << 0),
  66         KERNEL_PARAM_FL_HWPARAM = (1 << 1),
  67 };
  68
  69 struct kernel_param {
  70         const char *name;
  71         struct module *mod;
  72         const struct kernel_param_ops *ops;
  73         const u16 perm;
  74         s8 level;
  75         u8 flags;
  76         union {
  77                 void *arg;
  78                 const struct kparam_string *str;
  79                 const struct kparam_array *arr;
  80         };
  81 };
  82
  83 extern const struct kernel_param __start___param[], __stop___param[];
  84
  85 /* Special one for strings we want to copy into */
  86 struct kparam_string {
  87         unsigned int maxlen;
  88         char *string;
  89 };
  90
  91 /* Special one for arrays */
  92 struct kparam_array
  93 {
  94         unsigned int max;
  95         unsigned int elemsize;
  96         unsigned int *num;
  97         const struct kernel_param_ops *ops;
  98         void *elem;
  99 };
 100
 101 /**
 102  * module_param - typesafe helper for a module/cmdline parameter
 103  * @value: the variable to alter, and exposed parameter name.
 104  * @type: the type of the parameter
 105  * @perm: visibility in sysfs.
 106  *
 107  * @value becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
 108  * ".") the kernel commandline parameter.  Note that - is changed to _, so
 109  * the user can use "foo-bar=1" even for variable "foo_bar".
 110  *
 111  * @perm is 0 if the the variable is not to appear in sysfs, or 0444
 112  * for world-readable, 0644 for root-writable, etc.  Note that if it
 113  * is writable, you may need to use kernel_param_lock() around
 114  * accesses (esp. charp, which can be kfreed when it changes).
 115  *
 116  * The @type is simply pasted to refer to a param_ops_##type and a
 117  * param_check_##type: for convenience many standard types are provided but
 118  * you can create your own by defining those variables.
 119  *
 120  * Standard types are:
 121  *      byte, short, ushort, int, uint, long, ulong
 122  *      charp: a character pointer
 123  *      bool: a bool, values 0/1, y/n, Y/N.
 124  *      invbool: the above, only sense-reversed (N = true).
 125  */
 126 #define module_param(name, type, perm)                          \
 127         module_param_named(name, name, type, perm)
 128
 129 /**
 130  * module_param_unsafe - same as module_param but taints kernel
 131  */
 132 #define module_param_unsafe(name, type, perm)                   \
 133         module_param_named_unsafe(name, name, type, perm)
 134
 135 /**
 136  * module_param_named - typesafe helper for a renamed module/cmdline parameter
 137  * @name: a valid C identifier which is the parameter name.
 138  * @value: the actual lvalue to alter.
 139  * @type: the type of the parameter
 140  * @perm: visibility in sysfs.
 141  *
 142  * Usually it's a good idea to have variable names and user-exposed names the
 143  * same, but that's harder if the variable must be non-static or is inside a
 144  * structure.  This allows exposure under a different name.
 145  */
 146 #define module_param_named(name, value, type, perm)                        \
 147         param_check_##type(name, &(value));                                \
 148         module_param_cb(name, &param_ops_##type, &value, perm);            \
 149         __MODULE_PARM_TYPE(name, #type)
 150
 151 /**
 152  * module_param_named_unsafe - same as module_param_named but taints kernel
 153  */
 154 #define module_param_named_unsafe(name, value, type, perm)              \
 155         param_check_##type(name, &(value));                             \
 156         module_param_cb_unsafe(name, &param_ops_##type, &value, perm);  \
 157         __MODULE_PARM_TYPE(name, #type)
 158
 159 /**
 160  * module_param_cb - general callback for a module/cmdline parameter
 161  * @name: a valid C identifier which is the parameter name.
 162  * @ops: the set & get operations for this parameter.
 163  * @perm: visibility in sysfs.
 164  *
 165  * The ops can have NULL set or get functions.
 166  */
 167 #define module_param_cb(name, ops, arg, perm)                                 \
 168         __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1, 0)
 169
 170 #define module_param_cb_unsafe(name, ops, arg, perm)                          \
 171         __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1,    \
 172                             KERNEL_PARAM_FL_UNSAFE)
 173
 174 /**
 175  * <level>_param_cb - general callback for a module/cmdline parameter
 176  *                    to be evaluated before certain initcall level
 177  * @name: a valid C identifier which is the parameter name.
 178  * @ops: the set & get operations for this parameter.
 179  * @perm: visibility in sysfs.
 180  *
 181  * The ops can have NULL set or get functions.
 182  */
 183 #define __level_param_cb(name, ops, arg, perm, level)                   \
 184         __module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, level, 0)
 185
 186 #define core_param_cb(name, ops, arg, perm)             \
 187         __level_param_cb(name, ops, arg, perm, 1)
 188
 189 #define postcore_param_cb(name, ops, arg, perm)         \
 190         __level_param_cb(name, ops, arg, perm, 2)
 191
 192 #define arch_param_cb(name, ops, arg, perm)             \
 193         __level_param_cb(name, ops, arg, perm, 3)
 194
 195 #define subsys_param_cb(name, ops, arg, perm)           \
 196         __level_param_cb(name, ops, arg, perm, 4)
 197
 198 #define fs_param_cb(name, ops, arg, perm)               \
 199         __level_param_cb(name, ops, arg, perm, 5)
 200
 201 #define device_param_cb(name, ops, arg, perm)           \
 202         __level_param_cb(name, ops, arg, perm, 6)
 203
 204 #define late_param_cb(name, ops, arg, perm)             \
 205         __level_param_cb(name, ops, arg, perm, 7)
 206
 207 /* On alpha, ia64 and ppc64 relocations to global data cannot go into
 208    read-only sections (which is part of respective UNIX ABI on these
 209    platforms). So 'const' makes no sense and even causes compile failures
 210    with some compilers. */
 211 #if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
 212 #define __moduleparam_const
 213 #else
 214 #define __moduleparam_const const
 215 #endif
 216
 217 /* This is the fundamental function for registering boot/module
 218    parameters. */
 219 #define __module_param_call(prefix, name, ops, arg, perm, level, flags) \
 220         /* Default value instead of permissions? */                     \
 221         static const char __param_str_##name[] = prefix #name;          \
 222         static struct kernel_param __moduleparam_const __param_##name   \
 223         __used                                                          \
 224     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
 225         = { __param_str_##name, THIS_MODULE, ops,                       \
 226             VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } }
 227
 228 /* Obsolete - use module_param_cb() */
 229 #define module_param_call(name, _set, _get, arg, perm)                  \
 230         static const struct kernel_param_ops __param_ops_##name =       \
 231                 { .flags = 0, .set = _set, .get = _get };               \
 232         __module_param_call(MODULE_PARAM_PREFIX,                        \
 233                             name, &__param_ops_##name, arg, perm, -1, 0)
 234
 235 #ifdef CONFIG_SYSFS
 236 extern void kernel_param_lock(struct module *mod);
 237 extern void kernel_param_unlock(struct module *mod);
 238 #else
 239 static inline void kernel_param_lock(struct module *mod)
 240 {
 241 }
 242 static inline void kernel_param_unlock(struct module *mod)
 243 {
 244 }
 245 #endif
 246
 247 #ifndef MODULE
 248 /**
 249  * core_param - define a historical core kernel parameter.
 250  * @name: the name of the cmdline and sysfs parameter (often the same as var)
 251  * @var: the variable
 252  * @type: the type of the parameter
 253  * @perm: visibility in sysfs
 254  *
 255  * core_param is just like module_param(), but cannot be modular and
 256  * doesn't add a prefix (such as "printk.").  This is for compatibility
 257  * with __setup(), and it makes sense as truly core parameters aren't
 258  * tied to the particular file they're in.
 259  */
 260 #define core_param(name, var, type, perm)                               \
 261         param_check_##type(name, &(var));                               \
 262         __module_param_call("", name, &param_ops_##type, &var, perm, -1, 0)
 263
 264 /**
 265  * core_param_unsafe - same as core_param but taints kernel
 266  */
 267 #define core_param_unsafe(name, var, type, perm)                \
 268         param_check_##type(name, &(var));                               \
 269         __module_param_call("", name, &param_ops_##type, &var, perm,    \
 270                             -1, KERNEL_PARAM_FL_UNSAFE)
 271
 272 #endif /* !MODULE */
 273
 274 /**
 275  * module_param_string - a char array parameter
 276  * @name: the name of the parameter
 277  * @string: the string variable
 278  * @len: the maximum length of the string, incl. terminator
 279  * @perm: visibility in sysfs.
 280  *
 281  * This actually copies the string when it's set (unlike type charp).
 282  * @len is usually just sizeof(string).
 283  */
 284 #define module_param_string(name, string, len, perm)                    \
 285         static const struct kparam_string __param_string_##name         \
 286                 = { len, string };                                      \
 287         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 288                             &param_ops_string,                          \
 289                             .str = &__param_string_##name, perm, -1, 0);\
 290         __MODULE_PARM_TYPE(name, "string")
 291
 292 /**
 293  * parameq - checks if two parameter names match
 294  * @name1: parameter name 1
 295  * @name2: parameter name 2
 296  *
 297  * Returns true if the two parameter names are equal.
 298  * Dashes (-) are considered equal to underscores (_).
 299  */
 300 extern bool parameq(const char *name1, const char *name2);
 301
 302 /**
 303  * parameqn - checks if two parameter names match
 304  * @name1: parameter name 1
 305  * @name2: parameter name 2
 306  * @n: the length to compare
 307  *
 308  * Similar to parameq(), except it compares @n characters.
 309  */
 310 extern bool parameqn(const char *name1, const char *name2, size_t n);
 311
 312 /* Called on module insert or kernel boot */
 313 extern char *parse_args(const char *name,
 314                       char *args,
 315                       const struct kernel_param *params,
 316                       unsigned num,
 317                       s16 level_min,
 318                       s16 level_max,
 319                       void *arg,
 320                       int (*unknown)(char *param, char *val,
 321                                      const char *doing, void *arg));
 322
 323 /* Called by module remove. */
 324 #ifdef CONFIG_SYSFS
 325 extern void destroy_params(const struct kernel_param *params, unsigned num);
 326 #else
 327 static inline void destroy_params(const struct kernel_param *params,
 328                                   unsigned num)
 329 {
 330 }
 331 #endif /* !CONFIG_SYSFS */
 332
 333 /* All the helper functions */
 334 /* The macros to do compile-time type checking stolen from Jakub
 335    Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
 336 #define __param_check(name, p, type) \
 337         static inline type __always_unused *__check_##name(void) { return(p); }
 338
 339 extern const struct kernel_param_ops param_ops_byte;
 340 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 341 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 342 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 343
 344 extern const struct kernel_param_ops param_ops_short;
 345 extern int param_set_short(const char *val, const struct kernel_param *kp);
 346 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 347 #define param_check_short(name, p) __param_check(name, p, short)
 348
 349 extern const struct kernel_param_ops param_ops_ushort;
 350 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 351 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 352 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 353
 354 extern const struct kernel_param_ops param_ops_int;
 355 extern int param_set_int(const char *val, const struct kernel_param *kp);
 356 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 357 #define param_check_int(name, p) __param_check(name, p, int)
 358
 359 extern const struct kernel_param_ops param_ops_uint;
 360 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 361 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 362 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 363
 364 extern const struct kernel_param_ops param_ops_long;
 365 extern int param_set_long(const char *val, const struct kernel_param *kp);
 366 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 367 #define param_check_long(name, p) __param_check(name, p, long)
 368
 369 extern const struct kernel_param_ops param_ops_ulong;
 370 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 371 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 372 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 373
 374 extern const struct kernel_param_ops param_ops_ullong;
 375 extern int param_set_ullong(const char *val, const struct kernel_param *kp);
 376 extern int param_get_ullong(char *buffer, const struct kernel_param *kp);
 377 #define param_check_ullong(name, p) __param_check(name, p, unsigned long long)
 378
 379 extern const struct kernel_param_ops param_ops_charp;
 380 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 381 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 382 extern void param_free_charp(void *arg);
 383 #define param_check_charp(name, p) __param_check(name, p, char *)
 384
 385 /* We used to allow int as well as bool.  We're taking that away! */
 386 extern const struct kernel_param_ops param_ops_bool;
 387 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 388 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 389 #define param_check_bool(name, p) __param_check(name, p, bool)
 390
 391 extern const struct kernel_param_ops param_ops_bool_enable_only;
 392 extern int param_set_bool_enable_only(const char *val,
 393                                       const struct kernel_param *kp);
 394 /* getter is the same as for the regular bool */
 395 #define param_check_bool_enable_only param_check_bool
 396
 397 extern const 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 const 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, 0);                               \
 445         __MODULE_PARM_TYPE(name, "array of " #type)
 446
 447 enum hwparam_type {
 448         hwparam_ioport,         /* Module parameter configures an I/O port */
 449         hwparam_iomem,          /* Module parameter configures an I/O mem address */
 450         hwparam_ioport_or_iomem, /* Module parameter could be either, depending on other option */
 451         hwparam_irq,            /* Module parameter configures an IRQ */
 452         hwparam_dma,            /* Module parameter configures a DMA channel */
 453         hwparam_dma_addr,       /* Module parameter configures a DMA buffer address */
 454         hwparam_other,          /* Module parameter configures some other value */
 455 };
 456
 457 /**
 458  * module_param_hw_named - A parameter representing a hw parameters
 459  * @name: a valid C identifier which is the parameter name.
 460  * @value: the actual lvalue to alter.
 461  * @type: the type of the parameter
 462  * @hwtype: what the value represents (enum hwparam_type)
 463  * @perm: visibility in sysfs.
 464  *
 465  * Usually it's a good idea to have variable names and user-exposed names the
 466  * same, but that's harder if the variable must be non-static or is inside a
 467  * structure.  This allows exposure under a different name.
 468  */
 469 #define module_param_hw_named(name, value, type, hwtype, perm)          \
 470         param_check_##type(name, &(value));                             \
 471         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 472                             &param_ops_##type, &value,                  \
 473                             perm, -1,                                   \
 474                             KERNEL_PARAM_FL_HWPARAM | (hwparam_##hwtype & 0));  \
 475         __MODULE_PARM_TYPE(name, #type)
 476
 477 #define module_param_hw(name, type, hwtype, perm)               \
 478         module_param_hw_named(name, name, type, hwtype, perm)
 479
 480 /**
 481  * module_param_hw_array - A parameter representing an array of hw parameters
 482  * @name: the name of the array variable
 483  * @type: the type, as per module_param()
 484  * @hwtype: what the value represents (enum hwparam_type)
 485  * @nump: optional pointer filled in with the number written
 486  * @perm: visibility in sysfs
 487  *
 488  * Input and output are as comma-separated values.  Commas inside values
 489  * don't work properly (eg. an array of charp).
 490  *
 491  * ARRAY_SIZE(@name) is used to determine the number of elements in the
 492  * array, so the definition must be visible.
 493  */
 494 #define module_param_hw_array(name, type, hwtype, nump, perm)           \
 495         param_check_##type(name, &(name)[0]);                           \
 496         static const struct kparam_array __param_arr_##name             \
 497         = { .max = ARRAY_SIZE(name), .num = nump,                       \
 498             .ops = &param_ops_##type,                                   \
 499             .elemsize = sizeof(name[0]), .elem = name };                \
 500         __module_param_call(MODULE_PARAM_PREFIX, name,                  \
 501                             &param_array_ops,                           \
 502                             .arr = &__param_arr_##name,                 \
 503                             perm, -1,                                   \
 504                             KERNEL_PARAM_FL_HWPARAM | (hwparam_##hwtype & 0));  \
 505         __MODULE_PARM_TYPE(name, "array of " #type)
 506
 507
 508 extern const struct kernel_param_ops param_array_ops;
 509
 510 extern const struct kernel_param_ops param_ops_string;
 511 extern int param_set_copystring(const char *val, const struct kernel_param *);
 512 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 513
 514 /* for exporting parameters in /sys/module/.../parameters */
 515
 516 struct module;
 517
 518 #if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
 519 extern int module_param_sysfs_setup(struct module *mod,
 520                                     const struct kernel_param *kparam,
 521                                     unsigned int num_params);
 522
 523 extern void module_param_sysfs_remove(struct module *mod);
 524 #else
 525 static inline int module_param_sysfs_setup(struct module *mod,
 526                              const struct kernel_param *kparam,
 527                              unsigned int num_params)
 528 {
 529         return 0;
 530 }
 531
 532 static inline void module_param_sysfs_remove(struct module *mod)
 533 { }
 534 #endif
 535
 536 #endif /* _LINUX_MODULE_PARAMS_H */