genode/repos/base-pistachio/src/lib/base/ipc.cc

/*
 * \brief  IPC implementation for Pistachio
 * \author Julian Stecklina
 * \author Norman Feske
 * \date   2008-01-28
 */

/*
 * Copyright (C) 2008-2017 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU Affero General Public License version 3.
 */

/* Genode includes */
#include <base/log.h>
#include <base/ipc.h>
#include <base/blocking.h>
#include <base/sleep.h>

/* base-internal includes */
#include <base/internal/ipc_server.h>
#include <base/internal/capability_space_tpl.h>

/* Pistachio includes */
namespace Pistachio {
#include <l4/types.h>
#include <l4/ipc.h>
}

using namespace Genode;
using namespace Pistachio;


/**
 * Assert that we got 1 untyped word and 2 typed words
 */
static inline void check_ipc_result(L4_MsgTag_t result, L4_Word_t error_code)
{
	/*
	 * Test for IPC cancellation via Core's cancel-blocking mechanism
	 */
	enum { ERROR_MASK = 0xe, ERROR_CANCELED = 3 << 1 };
	if (L4_IpcFailed(result) &&
	    ((L4_ErrorCode() & ERROR_MASK) == ERROR_CANCELED))
		throw Genode::Blocking_canceled();

	/*
	 * Provide diagnostic information on unexpected conditions
	 */
	if (L4_IpcFailed(result)) {
		raw("Error in thread ", Hex(L4_Myself().raw), ". IPC failed.");
		throw Genode::Ipc_error();
	}

	if (L4_UntypedWords(result) < 2) {
		raw("Error in thread ", Hex(L4_Myself().raw), ". "
		    "Expected at leat two untyped words, but got ", L4_UntypedWords(result), ".\n");
		throw Genode::Ipc_error();
	}
}


/**
 * Configure L4 receive buffer according to Genode receive buffer
 */
static void extract_caps(L4_Msg_t &msg, Msgbuf_base &rcv_msg)
{
	using namespace Pistachio;

	L4_Word_t const num_caps = min((unsigned)Msgbuf_base::MAX_CAPS_PER_MSG,
	                               L4_Get(&msg, 1));
	for (unsigned i = 0; i < num_caps; i++) {

		L4_ThreadId_t tid;
		tid.raw = L4_Get(&msg, 2 + i*2);

		Rpc_obj_key const rpc_obj_key(L4_Get(&msg, 2 + i*2 + 1));

		bool const cap_valid = tid.raw != 0UL;

		Native_capability cap;

		if (cap_valid) {

			cap = Capability_space::lookup(rpc_obj_key);

			if (!cap.valid())
				cap = Capability_space::import(tid, rpc_obj_key);
		}

		rcv_msg.insert(cap);
	}
}


/**
 * Configure L4 message descriptor according to Genode send buffer
 */
static void prepare_send(L4_Word_t protocol_value, L4_Msg_t &msg,
                         Msgbuf_base &snd_msg)
{
	L4_Clear(&msg);
	L4_Append(&msg, protocol_value);

	L4_Append(&msg, (L4_Word_t)snd_msg.used_caps());

	for (unsigned i = 0; i < snd_msg.used_caps(); i++) {

		Native_capability cap = snd_msg.cap(i);

		if (cap.valid()) {
			Capability_space::Ipc_cap_data const cap_data =
				Capability_space::ipc_cap_data(snd_msg.cap(i));

			L4_Append(&msg, (L4_Word_t)cap_data.dst.raw);
			L4_Append(&msg, (L4_Word_t)cap_data.rpc_obj_key.value());
		} else {
			L4_Append(&msg, (L4_Word_t)0UL);
			L4_Append(&msg, (L4_Word_t)0UL);
		}
	}

	L4_Append(&msg, L4_StringItem(snd_msg.data_size(), snd_msg.data()));
	L4_Load(&msg);
}


static void prepare_receive(L4_MsgBuffer_t &l4_msgbuf, Msgbuf_base &rcv_msg)
{
	L4_Clear(&l4_msgbuf);
	L4_Append(&l4_msgbuf, L4_StringItem(rcv_msg.capacity(), rcv_msg.data()));
	L4_Accept(L4_UntypedWordsAcceptor);
	L4_Accept(L4_StringItemsAcceptor, &l4_msgbuf);
}


/****************
 ** IPC client **
 ****************/

Rpc_exception_code Genode::ipc_call(Native_capability dst,
                                    Msgbuf_base &snd_msg, Msgbuf_base &rcv_msg,
                                    size_t)
{
	/* prepare receive message buffer */
	L4_MsgBuffer_t msgbuf;
	prepare_receive(msgbuf, rcv_msg);

	Capability_space::Ipc_cap_data const dst_data =
		Capability_space::ipc_cap_data(dst);

	/* prepare sending parameters */
	L4_Msg_t msg;
	prepare_send(dst_data.rpc_obj_key.value(), msg, snd_msg);

	L4_MsgTag_t result = L4_Call(dst_data.dst);

	L4_Clear(&msg);
	L4_Store(result, &msg);

	check_ipc_result(result, L4_ErrorCode());

	extract_caps(msg, rcv_msg);

	return Rpc_exception_code(L4_Get(&msg, 0));
}


/****************
 ** IPC server **
 ****************/

void Genode::ipc_reply(Native_capability caller, Rpc_exception_code exc,
                       Msgbuf_base &snd_msg)
{
	L4_Msg_t msg;
	prepare_send(exc.value, msg, snd_msg);

	L4_MsgTag_t result = L4_Reply(Capability_space::ipc_cap_data(caller).dst);
	if (L4_IpcFailed(result))
		raw("ipc error in _reply, ignored");

	snd_msg.reset();
}


Genode::Rpc_request Genode::ipc_reply_wait(Reply_capability const         &last_caller,
                                           Rpc_exception_code              exc,
                                           Msgbuf_base                    &reply_msg,
                                           Msgbuf_base                    &request_msg,
                                           Rpc_entrypoint::Native_context &)
{
	bool need_to_wait = true;

	L4_MsgTag_t request_tag;

	request_msg.reset();

	/* prepare receive buffer for request */
	L4_MsgBuffer_t request_msgbuf;
	prepare_receive(request_msgbuf, request_msg);

	L4_ThreadId_t caller = L4_nilthread;

	if (last_caller.valid() && exc.value != Rpc_exception_code::INVALID_OBJECT) {

		/* prepare reply massage */
		L4_Msg_t reply_l4_msg;
		prepare_send(exc.value, reply_l4_msg, reply_msg);

		/* send reply and wait for new request message */
		request_tag = L4_Ipc(Capability_space::ipc_cap_data(last_caller).dst,
		                     L4_anythread,
		                     L4_Timeouts(L4_ZeroTime, L4_Never), &caller);

		if (!L4_IpcFailed(request_tag))
			need_to_wait = false;
	}

	while (need_to_wait) {

		/* wait for new request message */
		request_tag = L4_Wait(&caller);

		if (!L4_IpcFailed(request_tag))
			need_to_wait = false;
	}

	/* extract request parameters */
	L4_Msg_t msg;
	L4_Clear(&msg);
	L4_Store(request_tag, &msg);
	extract_caps(msg, request_msg);

	unsigned long const badge = L4_Get(&msg, 0);
	return Rpc_request(Capability_space::import(caller, Rpc_obj_key()), badge);
}


Ipc_server::Ipc_server(Rpc_entrypoint::Native_context& _native_context)
:
	Native_capability(Capability_space::import(Pistachio::L4_Myself(), Rpc_obj_key())),
	_native_context(_native_context)
{ }


Ipc_server::~Ipc_server() { }