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1/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */2#ifndef _RSEQ_ABI_H3#define _RSEQ_ABI_H4 5/*6 * rseq-abi.h7 *8 * Restartable sequences system call API9 *10 * Copyright (c) 2015-2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>11 */12 13#include <linux/types.h>14#include <asm/byteorder.h>15 16enum rseq_abi_cpu_id_state {17 RSEQ_ABI_CPU_ID_UNINITIALIZED = -1,18 RSEQ_ABI_CPU_ID_REGISTRATION_FAILED = -2,19};20 21enum rseq_abi_flags {22 RSEQ_ABI_FLAG_UNREGISTER = (1 << 0),23};24 25enum rseq_abi_cs_flags_bit {26 RSEQ_ABI_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,27 RSEQ_ABI_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,28 RSEQ_ABI_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,29};30 31enum rseq_abi_cs_flags {32 RSEQ_ABI_CS_FLAG_NO_RESTART_ON_PREEMPT =33 (1U << RSEQ_ABI_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),34 RSEQ_ABI_CS_FLAG_NO_RESTART_ON_SIGNAL =35 (1U << RSEQ_ABI_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),36 RSEQ_ABI_CS_FLAG_NO_RESTART_ON_MIGRATE =37 (1U << RSEQ_ABI_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),38};39 40/*41 * struct rseq_abi_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_abi_cs {46 /* Version of this structure. */47 __u32 version;48 /* enum rseq_abi_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_abi is aligned on 4 * 8 bytes to ensure it is always58 * contained within a single cache-line.59 *60 * A single struct rseq_abi per thread is allowed.61 */62struct rseq_abi {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 union {110 __u64 ptr64;111 112 /*113 * The "arch" field provides architecture accessor for114 * the ptr field based on architecture pointer size and115 * endianness.116 */117 struct {118#ifdef __LP64__119 __u64 ptr;120#elif defined(__BYTE_ORDER) ? (__BYTE_ORDER == __BIG_ENDIAN) : defined(__BIG_ENDIAN)121 __u32 padding; /* Initialized to zero. */122 __u32 ptr;123#else124 __u32 ptr;125 __u32 padding; /* Initialized to zero. */126#endif127 } arch;128 } rseq_cs;129 130 /*131 * Restartable sequences flags field.132 *133 * This field should only be updated by the thread which134 * registered this data structure. Read by the kernel.135 * Mainly used for single-stepping through rseq critical sections136 * with debuggers.137 *138 * - RSEQ_ABI_CS_FLAG_NO_RESTART_ON_PREEMPT139 * Inhibit instruction sequence block restart on preemption140 * for this thread.141 * - RSEQ_ABI_CS_FLAG_NO_RESTART_ON_SIGNAL142 * Inhibit instruction sequence block restart on signal143 * delivery for this thread.144 * - RSEQ_ABI_CS_FLAG_NO_RESTART_ON_MIGRATE145 * Inhibit instruction sequence block restart on migration for146 * this thread.147 */148 __u32 flags;149 150 /*151 * Restartable sequences node_id field. Updated by the kernel. Read by152 * user-space with single-copy atomicity semantics. This field should153 * only be read by the thread which registered this data structure.154 * Aligned on 32-bit. Contains the current NUMA node ID.155 */156 __u32 node_id;157 158 /*159 * Restartable sequences mm_cid field. Updated by the kernel. Read by160 * user-space with single-copy atomicity semantics. This field should161 * only be read by the thread which registered this data structure.162 * Aligned on 32-bit. Contains the current thread's concurrency ID163 * (allocated uniquely within a memory map).164 */165 __u32 mm_cid;166 167 /*168 * Flexible array member at end of structure, after last feature field.169 */170 char end[];171} __attribute__((aligned(4 * sizeof(__u64))));172 173#endif /* _RSEQ_ABI_H */174