[zion] Add a port create syscall

zion/include/zcall.h

@@ -90,6 +90,7 @@ void ZThreadExit();
                                    uint64_t* actual_bytes,
                                    uint64_t* actual_caps);
 
+[[nodiscard]] z_err_t ZPortCreate(uint64_t* port_cap);
 [[nodiscard]] z_err_t ZPortRecv(uint64_t port_cap, uint64_t num_bytes,
                                 uint8_t* bytes, uint64_t num_caps,
                                 uint64_t* caps, uint64_t* type,

zion/syscall/syscall.cpp

@@ -198,6 +198,12 @@ z_err_t ChannelRecv(ZChannelRecvReq* req) {
   return chan->Read(req->message);
 }
 
+z_err_t PortCreate(ZPortCreateResp* resp) {
+  auto& proc = gScheduler->CurrentProcess();
+  auto port = MakeRefCounted<Port>();
+  return proc.AddNewCapability(port, ZC_WRITE | ZC_READ);
+}
+
 z_err_t PortRecv(ZPortRecvReq* req) {
   auto& proc = gScheduler->CurrentProcess();
   auto port_cap = proc.GetCapability(req->port_cap);
@@ -275,6 +281,8 @@ extern "C" z_err_t SyscallHandler(uint64_t call_id, void* req, void* resp) {
       return ChannelSend(reinterpret_cast<ZChannelSendReq*>(req));
     case Z_CHANNEL_RECV:
       return ChannelRecv(reinterpret_cast<ZChannelRecvReq*>(req));
+    case Z_PORT_CREATE:
+      return PortCreate(reinterpret_cast<ZPortCreateResp*>(resp));
     case Z_PORT_RECV:
       return PortRecv(reinterpret_cast<ZPortRecvReq*>(req));
     case Z_PORT_POLL:

zion/usr/zcall.cpp

@@ -163,6 +163,13 @@ z_err_t ZChannelRecv(uint64_t chan_cap, uint64_t num_bytes, uint8_t* bytes,
   return ret;
 }
 
+z_err_t ZPortCreate(uint64_t* port_cap) {
+  ZPortCreateResp resp;
+  z_err_t ret = SysCall2(Z_PORT_CREATE, 0, &resp);
+  *port_cap = resp.port_cap;
+  return ret;
+}
+
 z_err_t ZPortRecv(uint64_t port_cap, uint64_t num_bytes, uint8_t* bytes,
                   uint64_t num_caps, uint64_t* caps, uint64_t* type,
                   uint64_t* actual_bytes, uint64_t* actual_caps) {

zion/usr/zcall_internal.h

@@ -86,6 +86,10 @@ struct ZChannelRecvReq {
   ZMessage message;
 };
 
+struct ZPortCreateResp {
+  uint64_t port_cap;
+};
+
 struct ZPortRecvReq {
   uint64_t port_cap;
   ZMessage message;