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104 lines
2.7 KiB
C++
104 lines
2.7 KiB
C++
/*
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* \brief NOVA-specific signal-source client interface
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* \author Norman Feske
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* \date 2010-02-03
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*
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* On NOVA, the signal source server does not provide a blocking
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* 'wait_for_signal' function because this kernel does no support
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* out-of-order IPC replies. Instead, we use a shared semaphore
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* to let the client block until a signal is present at the
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* server. The shared semaphore gets initialized with the first
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* call of 'wait_for_signal()'.
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*/
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/*
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* Copyright (C) 2010-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _INCLUDE__SIGNAL_SOURCE__CLIENT_H_
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#define _INCLUDE__SIGNAL_SOURCE__CLIENT_H_
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/* Genode includes */
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#include <base/rpc_client.h>
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#include <signal_source/nova_signal_source.h>
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/* base-internal includes */
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#include <base/internal/native_thread.h>
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/* NOVA includes */
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#include <nova/syscalls.h>
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#include <nova/util.h>
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#include <nova/capability_space.h>
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namespace Genode {
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class Signal_source_client : public Rpc_client<Nova_signal_source>
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{
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private:
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/**
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* Capability referring to a NOVA semaphore
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*/
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Native_capability _sem { };
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public:
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/**
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* Constructor
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*/
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Signal_source_client(Capability<Signal_source> cap)
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: Rpc_client<Nova_signal_source>(static_cap_cast<Nova_signal_source>(cap))
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{
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/* request mapping of semaphore capability selector */
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Thread * myself = Thread::myself();
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auto const &exc_base = myself->native_thread().exc_pt_sel;
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request_signal_sm_cap(exc_base + Nova::PT_SEL_PAGE_FAULT,
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exc_base + Nova::SM_SEL_SIGNAL);
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_sem = Capability_space::import(exc_base + Nova::SM_SEL_SIGNAL);
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call<Rpc_register_semaphore>(_sem);
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}
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~Signal_source_client()
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{
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Nova::revoke(Nova::Obj_crd(_sem.local_name(), 0));
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}
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/*****************************
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** Signal source interface **
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*****************************/
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Signal wait_for_signal() override
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{
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using namespace Nova;
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mword_t imprint, count;
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do {
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/*
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* We set an invalid imprint (0) to detect a spurious
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* unblock. In this case, NOVA does not block
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* SEMAPHORE_DOWN nor touch our input values if the
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* deblocking (chained) semaphore was dequeued before we
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* intend to block.
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*/
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imprint = 0;
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count = 0;
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/* block on semaphore until signal context was submitted */
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if (uint8_t res = si_ctrl(_sem.local_name(), SEMAPHORE_DOWN,
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imprint, count))
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warning("signal reception failed - error ", res);
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} while (imprint == 0);
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return Signal(imprint, count);
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}
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};
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}
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#endif /* _INCLUDE__SIGNAL_SOURCE__CLIENT_H_ */
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