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Diffstat (limited to 'pkg/abi/linux/rseq.go')
| -rw-r--r-- | pkg/abi/linux/rseq.go | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/pkg/abi/linux/rseq.go b/pkg/abi/linux/rseq.go new file mode 100644 index 000000000..76253ba30 --- /dev/null +++ b/pkg/abi/linux/rseq.go @@ -0,0 +1,130 @@ +// 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 +) |