136 lines
4.6 KiB
C
136 lines
4.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_RSEQ_H
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#define _UAPI_LINUX_RSEQ_H
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/*
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* linux/rseq.h
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*
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* Restartable sequences system call API
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*
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* Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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*/
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#include <linux/types.h>
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#include <asm/byteorder.h>
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enum rseq_cpu_id_state {
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RSEQ_CPU_ID_UNINITIALIZED = -1,
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RSEQ_CPU_ID_REGISTRATION_FAILED = -2,
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};
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enum rseq_flags {
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RSEQ_FLAG_UNREGISTER = (1 << 0),
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};
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enum rseq_cs_flags_bit {
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RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,
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RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,
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RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,
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};
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enum rseq_cs_flags {
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RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT =
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(1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
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RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL =
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(1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
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RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE =
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(1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
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};
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/*
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* struct rseq_cs is aligned on 4 * 8 bytes to ensure it is always
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* contained within a single cache-line. It is usually declared as
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* link-time constant data.
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*/
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struct rseq_cs {
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/* Version of this structure. */
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__u32 version;
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/* enum rseq_cs_flags */
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__u32 flags;
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__u64 start_ip;
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/* Offset from start_ip. */
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__u64 post_commit_offset;
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__u64 abort_ip;
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} __attribute__((aligned(4 * sizeof(__u64))));
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/*
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* struct rseq is aligned on 4 * 8 bytes to ensure it is always
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* contained within a single cache-line.
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*
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* A single struct rseq per thread is allowed.
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*/
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struct rseq {
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/*
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* Restartable sequences cpu_id_start field. Updated by the
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* kernel. Read by user-space with single-copy atomicity
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* semantics. This field should only be read by the thread which
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* registered this data structure. Aligned on 32-bit. Always
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* contains a value in the range of possible CPUs, although the
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* value may not be the actual current CPU (e.g. if rseq is not
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* initialized). This CPU number value should always be compared
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* against the value of the cpu_id field before performing a rseq
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* commit or returning a value read from a data structure indexed
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* using the cpu_id_start value.
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*/
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__u32 cpu_id_start;
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/*
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* Restartable sequences cpu_id field. Updated by the kernel.
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* Read by user-space with single-copy atomicity semantics. This
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* field should only be read by the thread which registered this
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* data structure. Aligned on 32-bit. Values
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* RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED
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* have a special semantic: the former means "rseq uninitialized",
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* and latter means "rseq initialization failed". This value is
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* meant to be read within rseq critical sections and compared
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* with the cpu_id_start value previously read, before performing
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* the commit instruction, or read and compared with the
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* cpu_id_start value before returning a value loaded from a data
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* structure indexed using the cpu_id_start value.
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*/
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__u32 cpu_id;
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/*
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* Restartable sequences rseq_cs field.
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*
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* Contains NULL when no critical section is active for the current
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* thread, or holds a pointer to the currently active struct rseq_cs.
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*
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* Updated by user-space, which sets the address of the currently
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* active rseq_cs at the beginning of assembly instruction sequence
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* block, and set to NULL by the kernel when it restarts an assembly
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* instruction sequence block, as well as when the kernel detects that
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* it is preempting or delivering a signal outside of the range
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* targeted by the rseq_cs. Also needs to be set to NULL by user-space
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* before reclaiming memory that contains the targeted struct rseq_cs.
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*
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* Read and set by the kernel. Set by user-space with single-copy
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* atomicity semantics. This field should only be updated by the
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* thread which registered this data structure. Aligned on 64-bit.
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*
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* 32-bit architectures should update the low order bits of the
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* rseq_cs field, leaving the high order bits initialized to 0.
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*/
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__u64 rseq_cs;
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/*
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* Restartable sequences flags field.
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*
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* This field should only be updated by the thread which
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* registered this data structure. Read by the kernel.
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* Mainly used for single-stepping through rseq critical sections
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* with debuggers.
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*
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* - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
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* Inhibit instruction sequence block restart on preemption
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* for this thread.
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* - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
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* Inhibit instruction sequence block restart on signal
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* delivery for this thread.
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* - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
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* Inhibit instruction sequence block restart on migration for
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* this thread.
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*/
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__u32 flags;
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} __attribute__((aligned(4 * sizeof(__u64))));
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#endif /* _UAPI_LINUX_RSEQ_H */
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