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// Copyright 2019 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
// Flags passed to rseq(2).
//
// Defined in include/uapi/linux/rseq.h.
const (
// RSEQ_FLAG_UNREGISTER unregisters the current thread.
RSEQ_FLAG_UNREGISTER = 1 << 0
)
// Critical section flags used in RSeqCriticalSection.Flags and RSeq.Flags.
//
// Defined in include/uapi/linux/rseq.h.
const (
// RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT inhibits restart on preemption.
RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT = 1 << 0
// RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL inhibits restart on signal
// delivery.
RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL = 1 << 1
// RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE inhibits restart on CPU
// migration.
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE = 1 << 2
)
// RSeqCriticalSection describes a restartable sequences critical section. It
// is equivalent to struct rseq_cs, defined in include/uapi/linux/rseq.h.
//
// In userspace, this structure is always aligned to 32 bytes.
//
// +marshal
type RSeqCriticalSection struct {
// Version is the version of this structure. Version 0 is defined here.
Version uint32
// Flags are the critical section flags, defined above.
Flags uint32
// Start is the start address of the critical section.
Start uint64
// PostCommitOffset is the offset from Start of the first instruction
// outside of the critical section.
PostCommitOffset uint64
// Abort is the abort address. It must be outside the critical section,
// and the 4 bytes prior must match the abort signature.
Abort uint64
}
const (
// SizeOfRSeqCriticalSection is the size of RSeqCriticalSection.
SizeOfRSeqCriticalSection = 32
// SizeOfRSeqSignature is the size of the signature immediately
// preceding RSeqCriticalSection.Abort.
SizeOfRSeqSignature = 4
)
// Special values for RSeq.CPUID, defined in include/uapi/linux/rseq.h.
const (
// RSEQ_CPU_ID_UNINITIALIZED indicates that this thread has not
// performed rseq initialization.
RSEQ_CPU_ID_UNINITIALIZED = ^uint32(0) // -1
// RSEQ_CPU_ID_REGISTRATION_FAILED indicates that rseq initialization
// failed.
RSEQ_CPU_ID_REGISTRATION_FAILED = ^uint32(1) // -2
)
// RSeq is the thread-local restartable sequences config/status. It
// is equivalent to struct rseq, defined in include/uapi/linux/rseq.h.
//
// In userspace, this structure is always aligned to 32 bytes.
type RSeq struct {
// CPUIDStart contains the current CPU ID if rseq is initialized.
//
// This field should only be read by the thread which registered this
// structure, and must be read atomically.
CPUIDStart uint32
// CPUID contains the current CPU ID or one of the CPU ID special
// values defined above.
//
// This field should only be read by the thread which registered this
// structure, and must be read atomically.
CPUID uint32
// RSeqCriticalSection is a pointer to the current RSeqCriticalSection
// block, or NULL. It is reset to NULL by the kernel on restart or
// non-restarting preempt/signal.
//
// This field should only be written by the thread which registered
// this structure, and must be written atomically.
RSeqCriticalSection uint64
// Flags are the critical section flags that apply to all critical
// sections on this thread, defined above.
Flags uint32
}
const (
// SizeOfRSeq is the size of RSeq.
//
// Note that RSeq is naively 24 bytes. However, it has 32-byte
// alignment, which in C increases sizeof to 32. That is the size that
// the Linux kernel uses.
SizeOfRSeq = 32
// AlignOfRSeq is the standard alignment of RSeq.
AlignOfRSeq = 32
// OffsetOfRSeqCriticalSection is the offset of RSeqCriticalSection in RSeq.
OffsetOfRSeqCriticalSection = 8
)
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