CEEOPC

C library interface: pthread_create()

CEEOPC creates a new thread in the caller's enclave and in the context of the current enclave with the specified attribute, attr. The new thread starts executing the routine at the entry point referred to by routine_addr with arg as its sole argument. When the routine returns, thread is implicitly terminated using the return value of the program as the termination status. The thread is detached according to the detachstate setting of the thread attribute specified at thread creation.

Upon successful completion of this function, the thread identifier of the newly created thread is returned in the location referred to by thread_id. Other threading functions may use thread_id as a token in their parameter lists to refer to the new thread.

Syntax

void CEEOPC (routine_addr, [arg], [attr], thread_id, [fc]

CEE_ENTRY   *routine_addr;
CEE_TOKEN   *arg;
CEE_PTAT    *attr;
CEE_THDID   *thread_id;
FEED_BACK   *fc;

CEEOPC

Call this CWI interface as follows:

L     R15,CEECAALEOV-CEECAA(,R12)     CAA address is in R12
L     R15,0048(,R15)
BALR  R14,R15

routine_addr (input)

The entry point of an external routine (not a nested procedure) that the new thread starts executing.

arg (input/optional)

An argument to be passed to the routine at its entry point. Its type is determined by the requirements of the routine called. This is the R1 value that is inbound to the target routine.

attr (input/optional)

The thread attributes object to be used for the new thread. When attr is omitted, the default attributes are used.

thread_id (output)

The unique thread identifier generated by Language Environment. It is used to refer to the new thread in other services. The thread identifier occupies a double word. The exact content of the thread identifier is not externalized.

fc (output/optional)

The feedback code returned by the service. It indicates the degree of success in creating the new thread.

The following message identifiers and associated severities can be returned by the service in the feedback code fc.

Condition
CEE000	Severity	0
	Msg_No	0000
	Message	The service completed successfully.
CEE5F1	Severity	3
	Msg_No	5601
	Message	The attributes object parameter did not contain a valid initialized attributes object (POSIX PTAT).
CEE5F4	Severity	3
	Msg_No	5604
	Message	A new thread could not be created due to some system-detected error with error code <err_code> and reason code <rsn_code>.
CEE5F5	Severity	3
	Msg_No	5605
	Message	There was not enough storage available to create the new thread.

Usage Notes:

It is assumed that routine_addr is currently available and does not require an explicit LOAD performed.
The new thread starts execution at the external procedure given in routine_addr and shares the context of the current enclave.
The thread shares all resources of the enclave.
The new thread has access to a new, independent stack. In particular, a new stack frame zero is provided.
The new thread inherits the execution priority from its creator. The size of the stack is determined by the stack size thread attribute.
The user must serialize use of shared resources, for instance, external data or arguments.
Arguments can be passed to the routine to be executed if the routine is declared to accept them. Output arguments and in/out arguments can be passed. Since the thread runs asynchronously with the creating thread, arguments passed by reference become shared variables and their use should be serialized, if necessary. Since the thread doesn't return to its creator, output arguments returned by value could be lost if the storage referred to by the arguments no longer exists. This might occur if the caller provided automatic storage for the arguments to the new thread.
POSIX provides a per-process signal vector and a per-thread signal mask.
The thread_id is used to refer to the thread as input to other services. No other use of thread_id is allowed.
Success of thread creation is reported by the fc. This does not report on success of Language Environment initialization in the new thread nor the successful execution of the code on the thread. If the fc is nonzero, thread_id is not valid. If the fc is zero, the thread_id is valid and can be used in functions that require thread identifiers.
The new thread's state is runnable.