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Andrei VaginandgVisor bot
a12c3a3f23
The systrap platform like the ptrace platform uses stub processes to manage the user address space. The difference is how they intercept system calls and other events like memory faults, exceptions, etc. In case of systrap, all events that have to be handled by the Sentry trigger signals that are handled by a custom signal handler installed on stub processes. The signal handler switches control to the Sentry. Here are a few other optimizations: * On x86, system calls can be replaced with a function call to remove overhead of signals. * For fast interactions of sentry and stub processes, futex wait/wake can be a bottle neck, so we use a polling mode. The platform is launched for the purpose of testing and gathering initial feedback. It is not yet ready for use in production. PiperOrigin-RevId: 511650064
40 lines
1.2 KiB
Go
40 lines
1.2 KiB
Go
// Copyright 2021 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package systrap
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import (
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"gvisor.dev/gvisor/pkg/hostarch"
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)
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const syscallStubMessageOffset = hostarch.PageSize
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// syscallSentryMessage is a shared message that can be changed only from the
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// Sentry and a stub process can only read it.
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type syscallSentryMessage struct {
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state uint32
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unused uint32
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sysno uint64
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args [6]uint64
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}
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// syscallStubMessage is a shared message that can be changed from a stub
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// process. It is used to notify the Sentry that a requested system call has
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// been executed.
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//
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// Attention: It can be compromised by user threads.
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type syscallStubMessage struct {
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ret uint64
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}
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