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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package linux
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/syserror"
)
// Membarrier implements syscall membarrier(2).
func Membarrier(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
cmd := args[0].Int()
flags := args[1].Int()
p := t.Kernel().Platform
if !p.HaveGlobalMemoryBarrier() {
// Event for applications that want membarrier on a configuration that
// doesn't support them.
t.Kernel().EmitUnimplementedEvent(t)
return 0, nil, syserror.ENOSYS
}
if flags != 0 {
return 0, nil, syserror.EINVAL
}
switch cmd {
case linux.MEMBARRIER_CMD_QUERY:
const supportedCommands = linux.MEMBARRIER_CMD_GLOBAL |
linux.MEMBARRIER_CMD_GLOBAL_EXPEDITED |
linux.MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED |
linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED |
linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED
return supportedCommands, nil, nil
case linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED:
if !t.MemoryManager().IsMembarrierPrivateEnabled() {
return 0, nil, syserror.EPERM
}
fallthrough
case linux.MEMBARRIER_CMD_GLOBAL, linux.MEMBARRIER_CMD_GLOBAL_EXPEDITED:
return 0, nil, p.GlobalMemoryBarrier()
case linux.MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED:
// no-op
return 0, nil, nil
case linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED:
t.MemoryManager().EnableMembarrierPrivate()
return 0, nil, nil
case linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE, linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE:
// We're aware of these, but they aren't implemented since no platform
// supports them yet.
t.Kernel().EmitUnimplementedEvent(t)
fallthrough
default:
return 0, nil, syserror.EINVAL
}
}
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