initial implementation of swap

+ Slightly unsure if it should be a syscall, or if assign would be
  enough. Also, which thread should run in a fork/spawn? For now, old
  thread, though this might increase latency. Or add swap flag to these
  calls?

3 files changed, 15 insertions, 6 deletions

diff --git a/common/proc.c b/common/proc.c
index 6a3bedf..946078b 100644
--- a/common/proc.c
+++ b/common/proc.c
@@ -37,9 +37,7 @@ stat_t init_proc(void *fdt)
 		return ERR_OOMEM;
 
 	/* set current tcb */
-	cpu_assign(t);
 	use_tcb(t);
-	use_vmem(t->proc.vmem);
 
 	/* allocate stacks after ELF file to make sure nothing of importance
 	 * clashes */
diff --git a/common/tcb.c b/common/tcb.c
index f618cd6..42e634d 100644
--- a/common/tcb.c
+++ b/common/tcb.c
@@ -305,9 +305,13 @@ struct tcb *cur_proc()
 
 void use_tcb(struct tcb *t)
 {
+	cpu_assign(t);
+
 	id_t cpu = cpu_id();
 	t->cpu_id = cpu;
 	cpu_tcb[cpu] = t;
+
+	use_vmem(t->proc.vmem);
 }
 
 struct tcb *get_tcb(id_t tid)
diff --git a/common/uapi/proc.c b/common/uapi/proc.c
index a668246..a9a3dce 100644
--- a/common/uapi/proc.c
+++ b/common/uapi/proc.c
@@ -12,6 +12,8 @@
 #include <apos/bits.h>
 #include <apos/mem_regions.h>
 
+#include <arch/proc.h>
+
 /**
  * Create syscall handler.
  *
@@ -122,10 +124,15 @@ SYSCALL_DEFINE1(kill)(sys_arg_t tid)
  * @return \ref OK and 0.
  */
 SYSCALL_DEFINE1(swap)(sys_arg_t tid){
-	/** \todo switch to process */
-	/** \todo should switch return the registers of the new thread that would
-	 * be used for message passing? */
-	return (struct sys_ret){ OK, 0, 0, 0, 0, 0 };
+	struct tcb *t = get_tcb(tid);
+	if (!t)
+		/** @todo add error sys_ret macro? */
+		return (struct sys_ret){ERR_INVAL, 0, 0, 0, 0, 0};
+
+	/* switch over to new thread */
+	use_tcb(t);
+	
+	return get_args(t);
 }
 
 /**