7f8bbe01be
The previous incarnation of this support used faults to make the CPU reexecute the system call instruction again and again to prevent emulating/passing through blocking system calls from blocking gem5 as a whole. That support was accidentally removed a while ago. This new version suspends the thread context executing the system call, and periodically wakes it up to retry using a periodically scheduled event. Jira Issue: https://gem5.atlassian.net/browse/GEM5-1123 Change-Id: I155fa8205d7ea45e3d102216aeca6ee1979a522f Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54205 Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com> Tested-by: kokoro <noreply+kokoro@google.com>
105 lines
3.4 KiB
C++
105 lines
3.4 KiB
C++
/*
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* Copyright (c) 2016 Advanced Micro Devices, Inc.
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* Copyright (c) 2003-2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "sim/syscall_desc.hh"
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#include "base/types.hh"
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#include "sim/eventq.hh"
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#include "sim/syscall_debug_macros.hh"
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namespace gem5
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{
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class ThreadContext;
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void
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SyscallDesc::doSyscall(ThreadContext *tc)
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{
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DPRINTF_SYSCALL(Base, "Calling %s...\n", dumper(name(), tc));
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SyscallReturn retval = executor(this, tc);
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if (retval.needsRetry()) {
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// Suspend this ThreadContext while the syscall is pending.
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tc->suspend();
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DPRINTF_SYSCALL(Base, "%s needs retry.\n", name());
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setupRetry(tc);
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return;
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}
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handleReturn(tc, retval);
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}
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void
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SyscallDesc::retrySyscall(ThreadContext *tc)
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{
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DPRINTF_SYSCALL(Base, "Retrying %s...\n", dumper(name(), tc));
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SyscallReturn retval = executor(this, tc);
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if (retval.needsRetry()) {
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DPRINTF_SYSCALL(Base, "%s still needs retry.\n", name());
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setupRetry(tc);
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return;
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}
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// We're done retrying, so reactivate this ThreadContext.
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tc->activate();
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handleReturn(tc, retval);
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}
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void
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SyscallDesc::setupRetry(ThreadContext *tc)
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{
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// Create an event which will retry the system call later.
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auto retry = [this, tc]() { retrySyscall(tc); };
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auto *event = new EventFunctionWrapper(retry, name(), true);
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// Schedule it in about 100 CPU cycles. That will give other contexts
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// a chance to execute a bit of code before trying again.
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auto *cpu = tc->getCpuPtr();
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curEventQueue()->schedule(event,
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curTick() + cpu->cyclesToTicks(Cycles(100)));
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}
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void
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SyscallDesc::handleReturn(ThreadContext *tc, const SyscallReturn &ret)
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{
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if (ret.suppressed()) {
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DPRINTF_SYSCALL(Base, "No return value.\n", name());
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} else {
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returnInto(tc, ret);
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DPRINTF_SYSCALL(Base, "Returned %d.\n", ret.encodedValue());
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}
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}
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} // namespace gem5
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