134 lines
4.4 KiB
C
134 lines
4.4 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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#ifdef __KERNEL__
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# include <linux/types.h>
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#else
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# include <stdint.h>
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#endif
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#include <linux/types_32_64.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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LINUX_FIELD_u32_u64(start_ip);
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/* Offset from start_ip. */
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LINUX_FIELD_u32_u64(post_commit_offset);
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LINUX_FIELD_u32_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, and read by user-space with single-copy atomicity
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* semantics. Aligned on 32-bit. Always contains a value in the
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* range of possible CPUs, although the value may not be the
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* actual current CPU (e.g. if rseq is not initialized). This
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* CPU number value should always be compared against the value
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* of the cpu_id field before performing a rseq commit or
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* returning a value read from a data structure indexed using
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* 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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* and read by user-space with single-copy atomicity semantics.
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* Aligned on 32-bit. Values RSEQ_CPU_ID_UNINITIALIZED and
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* RSEQ_CPU_ID_REGISTRATION_FAILED have a special semantic: the
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* former means "rseq uninitialized", and latter means "rseq
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* initialization failed". This value is meant to be read within
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* rseq critical sections and compared with the cpu_id_start
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* value previously read, before performing the commit instruction,
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* or read and compared with the cpu_id_start value before returning
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* a value loaded from a data structure indexed using the
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* 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 with single-copy atomicity semantics.
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* Set by user-space with single-copy atomicity semantics. Aligned
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* on 64-bit.
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*/
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LINUX_FIELD_u32_u64(rseq_cs);
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/*
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* - RSEQ_DISABLE flag:
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*
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* Fallback fast-track flag for single-stepping.
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* Set by user-space if lack of progress is detected.
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* Cleared by user-space after rseq finish.
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* Read by the kernel.
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* - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
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* Inhibit instruction sequence block restart and event
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* counter increment on preemption for this thread.
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* - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
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* Inhibit instruction sequence block restart and event
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* counter increment on signal delivery for this thread.
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* - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
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* Inhibit instruction sequence block restart and event
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* counter increment on migration for 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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