include/linux/moduleparam.h

Source file repositories/reference/linux-study-clean/include/linux/moduleparam.h

File Facts

System
Linux kernel
Corpus path
include/linux/moduleparam.h
Extension
.h
Size
23655 bytes
Lines
643
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct kernel_param_ops {
	/* How the ops should behave */
	unsigned int flags;
	/* Returns 0, or -errno.  arg is in kp->arg. */
	int (*set)(const char *val, const struct kernel_param *kp);
	/* Returns length written or -errno.  Buffer is 4k (ie. be short!) */
	int (*get)(char *buffer, const struct kernel_param *kp);
	/* Optional function to free kp->arg when module unloaded. */
	void (*free)(void *arg);
};

/*
 * Flags available for kernel_param
 *
 * UNSAFE - the parameter is dangerous and setting it will taint the kernel
 * HWPARAM - Hardware param not permitted in lockdown mode
 */
enum {
	KERNEL_PARAM_FL_UNSAFE	= (1 << 0),
	KERNEL_PARAM_FL_HWPARAM	= (1 << 1),
};

struct kernel_param {
	const char *name;
	struct module *mod;
	const struct kernel_param_ops *ops;
	const u16 perm;
	s8 level;
	u8 flags;
	union {
		void *arg;
		const struct kparam_string *str;
		const struct kparam_array *arr;
	};
};

extern const struct kernel_param __start___param[], __stop___param[];

/* Special one for strings we want to copy into */
struct kparam_string {
	unsigned int maxlen;
	char *string;
};

/* Special one for arrays */
struct kparam_array
{
	unsigned int max;
	unsigned int elemsize;
	unsigned int *num;
	const struct kernel_param_ops *ops;
	void *elem;
};

/**
 * module_param - typesafe helper for a module/cmdline parameter
 * @name: the variable to alter, and exposed parameter name.
 * @type: the type of the parameter
 * @perm: visibility in sysfs.
 *
 * @name becomes the module parameter, or (prefixed by KBUILD_MODNAME and a
 * ".") the kernel commandline parameter.  Note that - is changed to _, so
 * the user can use "foo-bar=1" even for variable "foo_bar".
 *
 * @perm is 0 if the variable is not to appear in sysfs, or 0444
 * for world-readable, 0644 for root-writable, etc.  Note that if it
 * is writable, you may need to use kernel_param_lock() around
 * accesses (esp. charp, which can be kfreed when it changes).
 *
 * The @type is simply pasted to refer to a param_ops_##type and a
 * param_check_##type: for convenience many standard types are provided but
 * you can create your own by defining those variables.
 *
 * Standard types are:
 *	byte, hexint, short, ushort, int, uint, long, ulong
 *	charp: a character pointer
 *	bool: a bool, values 0/1, y/n, Y/N.
 *	invbool: the above, only sense-reversed (N = true).
 */
#define module_param(name, type, perm)				\
	module_param_named(name, name, type, perm)

/**
 * module_param_unsafe - same as module_param but taints kernel
 * @name: the variable to alter, and exposed parameter name.
 * @type: the type of the parameter
 * @perm: visibility in sysfs.
 */
#define module_param_unsafe(name, type, perm)			\
	module_param_named_unsafe(name, name, type, perm)

Annotation

Implementation Notes