System calls

Portable parts of system call machinery. More...

Detailed Description

Portable parts of system call machinery.

Kernel contains mechanism of using kernel services.

This mechanism (commonly known as system calls, or syscalls) can be used to call system services only from userspace code running in thread context. It is not possible to call these services from within ISR context.

Macro Definition Documentation

___SVC

#define ___SVC

(

no

)

Value:

    asm volatile(\
            "SVC %[immediate]\n\t"\
                  "BX LR\n\t" : : [immediate] "I" (no) : "r0")

__SVC

#define __SVC	(		no,
			...
	)		___SVC(no)

Perform syscall.

Parameters

no	number of syscall.

Note

ARM port will throw arguments to SVC call, they are already where they should be.

__SYSCALL

#define __SYSCALL   __attribute__((naked)) __attribute__((noinline))

Mark function as syscall entrypoint in userspace.

This gives the function some common attributes. Currently syscall entrypoint are short functions which never get inlined and don't construct stack frame. This is the most efficient method of calling syscalls right now.

SYSCALL_DEFINITION

#define SYSCALL_DEFINITION   __attribute__((section(".syscall"), used)) const

Attribute used to publish syscall definitions in a way that os_syscall can process them.

Typedef Documentation

Syscall_Handler_t

typedef int(* Syscall_Handler_t) (unsigned long, unsigned long, unsigned long, unsigned long)

Enumeration Type Documentation

eSysCalls

enum eSysCalls

List of known syscall IDs.

These syscall IDs are known and can be used to call services.

Enumerator
SYSCALL_GET_TID
SYSCALL_SCHED_YIELD
SYSCALL_THREAD_CREATE
SYSCALL_MUTEX_INIT
SYSCALL_MUTEX_DESTROY
SYSCALL_MUTEX_UNLOCK
SYSCALL_MUTEX_TRYLOCK
SYSCALL_RPC_CALL
SYSCALL_RPC_RETURN
SYSCALL_THREAD_JOIN
SYSCALL_THREAD_EXIT
SYSCALL_SETITIMER
SYSCALL_USLEEP
SYSCALL_SIGNAL
SYSCALL_KILL
SYSCALL_SETPRIORITY
SYSCALL_RESET
SYSCALL_INIT_WAITABLE_OBJECT
SYSCALL_NOTIFY_OBJECT
SYSCALL_WAIT_FOR_OBJECT
SYSCALL_ENABLE_IRQ
SYSCALL_DISABLE_IRQ
SYSCALL_CPUFREQ_GET
SYSCALL_GET_MICROTIME
SYSCALL_SHUTDOWN
SYSCALL_NOTIFY_OBJECT2
SYSCALL_WAIT_FOR_OBJECT_VALUE
_SYSCALL_COUNT

Function Documentation

os_system_call()

int os_system_call	(	unsigned long	arg0,
		unsigned long	arg1,
		unsigned long	arg2,
		unsigned long	arg3,
		uint8_t	syscall_id
	)

Find and execute a system call.

Execution of system call is a portable action. It translates into calling a function determined by checking the syscall table. This function will call the syscall and return the return value it provided.

Parameters

arg0	1st argument to the syscall routine
arg1	2nd argument to the syscall routine
arg2	3rd argument to the syscall routine
arg3	4th argument to the syscall routine
syscall_id	the ID of system call routine that has to be called

Returns

value provided by the system call routine, if routine with given syscall_id exists. Otherwise returns E_NOTAVAIL.