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1/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */2#ifndef _UAPI_LINUX_RSEQ_H3#define _UAPI_LINUX_RSEQ_H4 5/*6 * linux/rseq.h7 *8 * Restartable sequences system call API9 *10 * Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>11 */12 13#include <linux/types.h>14#include <asm/byteorder.h>15 16enum rseq_cpu_id_state {17 RSEQ_CPU_ID_UNINITIALIZED = -1,18 RSEQ_CPU_ID_REGISTRATION_FAILED = -2,19};20 21enum rseq_flags {22 RSEQ_FLAG_UNREGISTER = (1 << 0),23};24 25enum rseq_cs_flags_bit {26 RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,27 RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,28 RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,29};30 31enum rseq_cs_flags {32 RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT =33 (1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),34 RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL =35 (1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),36 RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE =37 (1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),38};39 40/*41 * struct rseq_cs is aligned on 4 * 8 bytes to ensure it is always42 * contained within a single cache-line. It is usually declared as43 * link-time constant data.44 */45struct rseq_cs {46 /* Version of this structure. */47 __u32 version;48 /* enum rseq_cs_flags */49 __u32 flags;50 __u64 start_ip;51 /* Offset from start_ip. */52 __u64 post_commit_offset;53 __u64 abort_ip;54} __attribute__((aligned(4 * sizeof(__u64))));55 56/*57 * struct rseq is aligned on 4 * 8 bytes to ensure it is always58 * contained within a single cache-line.59 *60 * A single struct rseq per thread is allowed.61 */62struct rseq {63 /*64 * Restartable sequences cpu_id_start field. Updated by the65 * kernel. Read by user-space with single-copy atomicity66 * semantics. This field should only be read by the thread which67 * registered this data structure. Aligned on 32-bit. Always68 * contains a value in the range of possible CPUs, although the69 * value may not be the actual current CPU (e.g. if rseq is not70 * initialized). This CPU number value should always be compared71 * against the value of the cpu_id field before performing a rseq72 * commit or returning a value read from a data structure indexed73 * using the cpu_id_start value.74 */75 __u32 cpu_id_start;76 /*77 * Restartable sequences cpu_id field. Updated by the kernel.78 * Read by user-space with single-copy atomicity semantics. This79 * field should only be read by the thread which registered this80 * data structure. Aligned on 32-bit. Values81 * RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED82 * have a special semantic: the former means "rseq uninitialized",83 * and latter means "rseq initialization failed". This value is84 * meant to be read within rseq critical sections and compared85 * with the cpu_id_start value previously read, before performing86 * the commit instruction, or read and compared with the87 * cpu_id_start value before returning a value loaded from a data88 * structure indexed using the cpu_id_start value.89 */90 __u32 cpu_id;91 /*92 * Restartable sequences rseq_cs field.93 *94 * Contains NULL when no critical section is active for the current95 * thread, or holds a pointer to the currently active struct rseq_cs.96 *97 * Updated by user-space, which sets the address of the currently98 * active rseq_cs at the beginning of assembly instruction sequence99 * block, and set to NULL by the kernel when it restarts an assembly100 * instruction sequence block, as well as when the kernel detects that101 * it is preempting or delivering a signal outside of the range102 * targeted by the rseq_cs. Also needs to be set to NULL by user-space103 * before reclaiming memory that contains the targeted struct rseq_cs.104 *105 * Read and set by the kernel. Set by user-space with single-copy106 * atomicity semantics. This field should only be updated by the107 * thread which registered this data structure. Aligned on 64-bit.108 *109 * 32-bit architectures should update the low order bits of the110 * rseq_cs field, leaving the high order bits initialized to 0.111 */112 __u64 rseq_cs;113 114 /*115 * Restartable sequences flags field.116 *117 * This field should only be updated by the thread which118 * registered this data structure. Read by the kernel.119 * Mainly used for single-stepping through rseq critical sections120 * with debuggers.121 *122 * - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT123 * Inhibit instruction sequence block restart on preemption124 * for this thread.125 * - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL126 * Inhibit instruction sequence block restart on signal127 * delivery for this thread.128 * - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE129 * Inhibit instruction sequence block restart on migration for130 * this thread.131 */132 __u32 flags;133 134 /*135 * Restartable sequences node_id field. Updated by the kernel. Read by136 * user-space with single-copy atomicity semantics. This field should137 * only be read by the thread which registered this data structure.138 * Aligned on 32-bit. Contains the current NUMA node ID.139 */140 __u32 node_id;141 142 /*143 * Restartable sequences mm_cid field. Updated by the kernel. Read by144 * user-space with single-copy atomicity semantics. This field should145 * only be read by the thread which registered this data structure.146 * Aligned on 32-bit. Contains the current thread's concurrency ID147 * (allocated uniquely within a memory map).148 */149 __u32 mm_cid;150 151 /*152 * Flexible array member at end of structure, after last feature field.153 */154 char end[];155} __attribute__((aligned(4 * sizeof(__u64))));156 157#endif /* _UAPI_LINUX_RSEQ_H */158