clone() call working. Tested exit(), clone() and fork() mixture running about 22 threads, processes.

tasks/libposix/fork.c

@@ -65,8 +65,8 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
 	l4_set_tag(L4_IPC_TAG_CLONE);
 
 	/* Write the args as in usual ipc */
-	write_mr(L4SYS_ARG0, flags);
+	write_mr(L4SYS_ARG0, (unsigned long)child_stack);
-	write_mr(L4SYS_ARG1, (unsigned long)child_stack);
+	write_mr(L4SYS_ARG1, flags);
 
 	/* Perform an ipc but with different return logic. See implementation. */
 	if ((ret = arch_clone(PAGER_TID, PAGER_TID)) < 0) {

tasks/mm0/include/syscalls.h

@@ -32,6 +32,7 @@ int sys_shmdt(struct tcb *requester, const void *shmaddr);
 int sys_shmget(key_t key, int size, int shmflg);
 
 int sys_fork(struct tcb *parent);
+int sys_clone(struct tcb *parent, void *child_stack, unsigned int clone_flags);
 void sys_exit(struct tcb *task, int status);
 
 #endif /* __MM0_SYSARGS_H__ */

tasks/mm0/main.c

@@ -126,6 +126,10 @@ void handle_requests(void)
 		ret = sys_fork(sender);
 		break;
 	}
+	case L4_IPC_TAG_CLONE: {
+		ret = sys_clone(sender, (void *)mr[0], (unsigned int)mr[1]);
+		break;
+	}
 	case L4_IPC_TAG_EXIT: {
 		/* An exiting task has no receive phase */
 		sys_exit(sender, (int)mr[0]);

tasks/mm0/src/clone.c

@@ -122,10 +122,14 @@ int do_clone(struct tcb *parent, unsigned long child_stack, unsigned int flags)
 	child->stack_end = child_stack;
 	child->stack_start = 0;
 
-	/* Set child's stack pointer */
 	memset(&exregs, 0, sizeof(exregs));
+
+	/* Set child's stack pointer */
 	exregs_set_stack(&exregs, child_stack);
 
+	/* Set child's clone return value to 0 */
+	exregs_set_mr(&exregs, MR_RETURN, 0);
+
 	/* Do the actual exregs call to c0 */
 	if ((err = l4_exchange_registers(&exregs, child->tid)) < 0)
 		BUG();

tasks/mm0/src/task.c

@@ -61,13 +61,9 @@ struct tcb *find_task(int tid)
 {
 	struct tcb *t;
 
-	list_for_each_entry(t, &global_tasks.list, list) {
+	list_for_each_entry(t, &global_tasks.list, list)
-		/* A temporary precaution */
+		if (t->tid == tid)
-		BUG_ON(t->tid != t->spid);
-		if (t->tid == tid) {
 			return t;
-		}
-	}
 	return 0;
 }
 

tasks/test0/main.c

@@ -63,7 +63,11 @@ void main(void)
 	}
 
 	printf("Testing clone syscall...\n");
-	clonetest();
+	if ((pid = fork()) < 0)
+		printf("Error forking...\n");
+	/* Child does the clonetest(). All of them will exit */
+	if (pid == 0)
+		clonetest();
 
 	while (1)
 		wait_pager(0);

tasks/test0/src/clone.c

@@ -1,42 +0,0 @@
-/*
- * Clone test.
- */
-
-#include <stdio.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include <sys/mman.h>
-#include <sched.h>
-#include <errno.h>
-
-int my_thread_func(void *arg)
-{
-	printf("Cloned child running...\n");
-	printf("PID: %d\n", getpid());
-	_exit(0);
-}
-
-int clonetest(void)
-{
-	pid_t childid;
-	void *child_stack;
-
-	if ((child_stack = mmap(0, 0x1000, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_GROWSDOWN, 0, 0)) == MAP_FAILED) {
-		printf("MMAP failed.\n");
-		_exit(1);
-	} else {
-		printf("Mapped area starting at %p\n", child_stack);
-	}
-	((int *)child_stack)[-1] = 5; /* Test mapped area */
-
-	printf("Cloning...\n");
-
-	if ((childid = clone(my_thread_func, child_stack,
-			     CLONE_PARENT | CLONE_FS | CLONE_VM | CLONE_THREAD | CLONE_SIGHAND, 0)) < 0) {
-		perror("CLONE failed.\n");
-	} else {
-		printf("Cloned a new thread with child pid %d\n", childid);
-	}
-	return 0;
-}
-

tasks/test0/src/clonetest.c

@@ -0,0 +1,49 @@
+/*
+ * Clone test.
+ */
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sched.h>
+#include <errno.h>
+
+int clone_global = 0;
+
+int my_thread_func(void *arg)
+{
+	printf("Cloned child %d running...\n", getpid());
+	for (int i = 0; i < 25; i++)
+		clone_global++;
+	printf("Cloned child exiting with global increased to: %d. (Should be just about 100 at final)\n", clone_global);
+	_exit(0);
+}
+
+int clonetest(void)
+{
+	pid_t childid;
+	void *child_stack;
+
+	/* Parent loops and calls clone() to clone new threads. Children don't come back from the clone() call */
+	for (int i = 0; i < 4; i++) {
+		if ((child_stack = mmap(0, 0x1000, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_GROWSDOWN, 0, 0)) == MAP_FAILED) {
+			printf("MMAP failed.\n");
+			_exit(1);
+		} else {
+			printf("Mapped area starting at %p\n", child_stack);
+		}
+		((int *)child_stack)[-1] = 5; /* Test mapped area */
+
+		printf("Cloning...\n");
+
+		if ((childid = clone(my_thread_func, child_stack,
+		     CLONE_PARENT | CLONE_FS | CLONE_VM | CLONE_THREAD | CLONE_SIGHAND, 0)) < 0) {
+			perror("CLONE failed.\n");
+		} else {
+			printf("Cloned a new thread with child pid %d\n", childid);
+		}
+	}
+	_exit(0);
+	return 0;
+}
+