Xenomai API: Utility Services


Functions
int	rtdm_mmap_to_user (rtdm_user_info_t user_info, void src_addr, size_t len, int prot, void *pptr, struct vm_operations_struct vm_ops, void *vm_private_data)
	Map a kernel memory range into the address space of the user.
int	rtdm_iomap_to_user (rtdm_user_info_t user_info, unsigned long src_addr, size_t len, int prot, void pptr, struct vm_operations_struct vm_ops, void *vm_private_data)
	Map an I/O memory range into the address space of the user.
int	rtdm_munmap (rtdm_user_info_t user_info, void ptr, size_t len)
	Unmap a user memory range.
void	rtdm_printk (const char *format,...)
	Real-time safe message printing on kernel console.
void *	rtdm_malloc (size_t size)
	Allocate memory block in real-time context.
void	rtdm_free (void *ptr)
	Release real-time memory block.
int	rtdm_read_user_ok (rtdm_user_info_t user_info, const void __user ptr, size_t size)
	Check if read access to user-space memory block is safe.
int	rtdm_rw_user_ok (rtdm_user_info_t user_info, const void __user ptr, size_t size)
	Check if read/write access to user-space memory block is safe.
int	rtdm_copy_from_user (rtdm_user_info_t user_info, void dst, const void __user *src, size_t size)
	Copy user-space memory block to specified buffer.
int	rtdm_safe_copy_from_user (rtdm_user_info_t user_info, void dst, const void __user *src, size_t size)
	Check if read access to user-space memory block and copy it to specified buffer.
int	rtdm_copy_to_user (rtdm_user_info_t user_info, void __user dst, const void *src, size_t size)
	Copy specified buffer to user-space memory block.
int	rtdm_safe_copy_to_user (rtdm_user_info_t user_info, void __user dst, const void *src, size_t size)
	Check if read/write access to user-space memory block is safe and copy specified buffer to it.
int	rtdm_strncpy_from_user (rtdm_user_info_t user_info, char dst, const char __user *src, size_t count)
	Copy user-space string to specified buffer.
int	rtdm_in_rt_context (void)
	Test if running in a real-time task.

Function Documentation

int rtdm_copy_from_user	(	rtdm_user_info_t *	user_info,
		void *	dst,
		const void __user *	src,
		size_t	size
	)

Copy user-space memory block to specified buffer.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	dst	Destination buffer address
`[in]`	src	Address of the user-space memory block
`[in]`	size	Size of the memory block

Returns:: 0 on success, otherwise:

-EFAULT is returned if an invalid memory area was accessed.

Note:: Before invoking this service, verify via rtdm_read_user_ok() that the provided user-space address can securely be accessed.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_copy_to_user	(	rtdm_user_info_t *	user_info,
		void __user *	dst,
		const void *	src,
		size_t	size
	)

Copy specified buffer to user-space memory block.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	dst	Address of the user-space memory block
`[in]`	src	Source buffer address
`[in]`	size	Size of the memory block

Returns:: 0 on success, otherwise:

-EFAULT is returned if an invalid memory area was accessed.

Note:: Before invoking this service, verify via rtdm_rw_user_ok() that the provided user-space address can securely be accessed.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

void rtdm_free ( void * ptr )

Release real-time memory block.

Parameters:

[in] ptr Pointer to memory block as returned by rtdm_malloc()

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Interrupt service routine (consider the overhead!)
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_in_rt_context ( void )

Test if running in a real-time task.

Returns:: Non-zero is returned if the caller resides in real-time context, 0 otherwise.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_iomap_to_user	(	rtdm_user_info_t *	user_info,
		unsigned long	src_addr,
		size_t	len,
		int	prot,
		void **	pptr,
		struct vm_operations_struct *	vm_ops,
		void *	vm_private_data
	)

Map an I/O memory range into the address space of the user.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	src_addr	physical I/O address to be mapped
`[in]`	len	Length of the memory range
`[in]`	prot	Protection flags for the user's memory range, typically either PROT_READ or PROT_READ\|PROT_WRITE
`[in,out]`	pptr	Address of a pointer containing the desired user address or NULL on entry and the finally assigned address on return
`[in]`	vm_ops	vm_operations to be executed on the vma_area of the user memory range or NULL
`[in]`	vm_private_data	Private data to be stored in the vma_area, primarily useful for vm_operation handlers

Returns:: 0 on success, otherwise (most common values):

-EINVAL is returned if an invalid start address, size, or destination address was passed.

-ENOMEM is returned if there is insufficient free memory or the limit of memory mapping for the user process was reached.

-EAGAIN is returned if too much memory has been already locked by the user process.

-EPERM may be returned if an illegal invocation environment is detected.

Note:: RTDM supports two models for unmapping the user memory range again. One is explicit unmapping via rtdm_munmap(), either performed when the user requests it via an IOCTL etc. or when the related device is closed. The other is automatic unmapping, triggered by the user invoking standard munmap() or by the termination of the related process. To track release of the mapping and therefore relinquishment of the referenced physical memory, the caller of rtdm_iomap_to_user() can pass a vm_operations_struct on invocation, defining a close handler for the vm_area. See Linux documentaion (e.g. Linux Device Drivers book) on virtual memory management for details.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
User-space task (non-RT)

Rescheduling: possible.

void* rtdm_malloc ( size_t size )

Allocate memory block in real-time context.

Parameters:

[in] size Requested size of the memory block

Returns:: The pointer to the allocated block is returned on success, NULL otherwise.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Interrupt service routine (consider the overhead!)
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_mmap_to_user	(	rtdm_user_info_t *	user_info,
		void *	src_addr,
		size_t	len,
		int	prot,
		void **	pptr,
		struct vm_operations_struct *	vm_ops,
		void *	vm_private_data
	)

Map a kernel memory range into the address space of the user.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	src_addr	Kernel virtual address to be mapped
`[in]`	len	Length of the memory range
`[in]`	prot	Protection flags for the user's memory range, typically either PROT_READ or PROT_READ\|PROT_WRITE
`[in,out]`	pptr	Address of a pointer containing the desired user address or NULL on entry and the finally assigned address on return
`[in]`	vm_ops	vm_operations to be executed on the vma_area of the user memory range or NULL
`[in]`	vm_private_data	Private data to be stored in the vma_area, primarily useful for vm_operation handlers

Returns:: 0 on success, otherwise (most common values):

-EINVAL is returned if an invalid start address, size, or destination address was passed.

-ENOMEM is returned if there is insufficient free memory or the limit of memory mapping for the user process was reached.

-EAGAIN is returned if too much memory has been already locked by the user process.

-EPERM may be returned if an illegal invocation environment is detected.

Note:: This service only works on memory regions allocated via kmalloc() or vmalloc(). To map physical I/O memory to user-space use rtdm_iomap_to_user() instead.
RTDM supports two models for unmapping the user memory range again. One is explicit unmapping via rtdm_munmap(), either performed when the user requests it via an IOCTL etc. or when the related device is closed. The other is automatic unmapping, triggered by the user invoking standard munmap() or by the termination of the related process. To track release of the mapping and therefore relinquishment of the referenced physical memory, the caller of rtdm_mmap_to_user() can pass a vm_operations_struct on invocation, defining a close handler for the vm_area. See Linux documentaion (e.g. Linux Device Drivers book) on virtual memory management for details.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
User-space task (non-RT)

Rescheduling: possible.

int rtdm_munmap	(	rtdm_user_info_t *	user_info,
		void *	ptr,
		size_t	len
	)

Unmap a user memory range.

Parameters:

`[in]`	user_info	User information pointer as passed to rtdm_mmap_to_user() when requesting to map the memory range
`[in]`	ptr	User address or the memory range
`[in]`	len	Length of the memory range

Returns:: 0 on success, otherwise:

-EINVAL is returned if an invalid address or size was passed.

-EPERM may be returned if an illegal invocation environment is detected.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
User-space task (non-RT)

Rescheduling: possible.

void rtdm_printk	(	const char *	format,
			...
	)

Real-time safe message printing on kernel console.

Parameters:

`[in]`	format	Format string (conforming standard `printf()`)
	...	Arguments referred by format

Returns:: On success, this service returns the number of characters printed. Otherwise, a negative error code is returned.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Interrupt service routine (consider the overhead!)
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never in real-time context, possible in non-real-time environments.

int rtdm_read_user_ok	(	rtdm_user_info_t *	user_info,
		const void __user *	ptr,
		size_t	size
	)

Check if read access to user-space memory block is safe.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	ptr	Address of the user-provided memory block
`[in]`	size	Size of the memory block

Returns:: Non-zero is return when it is safe to read from the specified memory block, 0 otherwise.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_rw_user_ok	(	rtdm_user_info_t *	user_info,
		const void __user *	ptr,
		size_t	size
	)

Check if read/write access to user-space memory block is safe.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	ptr	Address of the user-provided memory block
`[in]`	size	Size of the memory block

Returns:: Non-zero is return when it is safe to read from or write to the specified memory block, 0 otherwise.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_safe_copy_from_user	(	rtdm_user_info_t *	user_info,
		void *	dst,
		const void __user *	src,
		size_t	size
	)

Check if read access to user-space memory block and copy it to specified buffer.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	dst	Destination buffer address
`[in]`	src	Address of the user-space memory block
`[in]`	size	Size of the memory block

Returns:: 0 on success, otherwise:

-EFAULT is returned if an invalid memory area was accessed.

Note:: This service is a combination of rtdm_read_user_ok and rtdm_copy_from_user.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_safe_copy_to_user	(	rtdm_user_info_t *	user_info,
		void __user *	dst,
		const void *	src,
		size_t	size
	)

Check if read/write access to user-space memory block is safe and copy specified buffer to it.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	dst	Address of the user-space memory block
`[in]`	src	Source buffer address
`[in]`	size	Size of the memory block

Returns:: 0 on success, otherwise:

-EFAULT is returned if an invalid memory area was accessed.

Note:: This service is a combination of rtdm_rw_user_ok and rtdm_copy_to_user.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

int rtdm_strncpy_from_user	(	rtdm_user_info_t *	user_info,
		char *	dst,
		const char __user *	src,
		size_t	count
	)

Copy user-space string to specified buffer.

Parameters:

`[in]`	user_info	User information pointer as passed to the invoked device operation handler
`[in]`	dst	Destination buffer address
`[in]`	src	Address of the user-space string
`[in]`	count	Maximum number of bytes to copy, including the trailing '0'

Returns:: Length of the string on success (not including the trailing '0'), otherwise:

-EFAULT is returned if an invalid memory area was accessed.

Note:: This services already includes a check of the source address, calling rtdm_read_user_ok() for src explicitly is not required.

Environments:

This service can be called from:

Kernel module initialization/cleanup code
Kernel-based task
User-space task (RT, non-RT)

Rescheduling: never.

Utility Services [Driver Development API]

Functions

Function Documentation

Utility Services
[Driver Development API]