1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
#ifndef _UAPI_LINUX_RSEQ_H
#define _UAPI_LINUX_RSEQ_H
/*
* linux/rseq.h
*
* Restartable sequences system call API
*
* Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*/
#include <linux/types.h>
#include <asm/byteorder.h>
enum rseq_cpu_id_state {
RSEQ_CPU_ID_UNINITIALIZED = -1,
RSEQ_CPU_ID_REGISTRATION_FAILED = -2,
};
enum rseq_flags {
RSEQ_FLAG_UNREGISTER = (1 << 0),
};
enum rseq_cs_flags_bit {
RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,
RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,
};
enum rseq_cs_flags {
RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT =
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL =
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE =
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
};
/*
* struct rseq_cs is aligned on 4 * 8 bytes to ensure it is always
* contained within a single cache-line. It is usually declared as
* link-time constant data.
*/
struct rseq_cs {
/* Version of this structure. */
__u32 version;
/* enum rseq_cs_flags */
__u32 flags;
__u64 start_ip;
/* Offset from start_ip. */
__u64 post_commit_offset;
__u64 abort_ip;
} __attribute__((aligned(4 * sizeof(__u64))));
/*
* struct rseq is aligned on 4 * 8 bytes to ensure it is always
* contained within a single cache-line.
*
* A single struct rseq per thread is allowed.
*/
struct rseq {
/*
* Restartable sequences cpu_id_start field. Updated by the
* kernel. Read by user-space with single-copy atomicity
* semantics. This field should only be read by the thread which
* registered this data structure. Aligned on 32-bit. Always
* contains a value in the range of possible CPUs, although the
* value may not be the actual current CPU (e.g. if rseq is not
* initialized). This CPU number value should always be compared
* against the value of the cpu_id field before performing a rseq
* commit or returning a value read from a data structure indexed
* using the cpu_id_start value.
*/
__u32 cpu_id_start;
/*
* Restartable sequences cpu_id field. Updated by the kernel.
* Read by user-space with single-copy atomicity semantics. This
* field should only be read by the thread which registered this
* data structure. Aligned on 32-bit. Values
* RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED
* have a special semantic: the former means "rseq uninitialized",
* and latter means "rseq initialization failed". This value is
* meant to be read within rseq critical sections and compared
* with the cpu_id_start value previously read, before performing
* the commit instruction, or read and compared with the
* cpu_id_start value before returning a value loaded from a data
* structure indexed using the cpu_id_start value.
*/
__u32 cpu_id;
/*
* Restartable sequences rseq_cs field.
*
* Contains NULL when no critical section is active for the current
* thread, or holds a pointer to the currently active struct rseq_cs.
*
* Updated by user-space, which sets the address of the currently
* active rseq_cs at the beginning of assembly instruction sequence
* block, and set to NULL by the kernel when it restarts an assembly
* instruction sequence block, as well as when the kernel detects that
* it is preempting or delivering a signal outside of the range
* targeted by the rseq_cs. Also needs to be set to NULL by user-space
* before reclaiming memory that contains the targeted struct rseq_cs.
*
* Read and set by the kernel. Set by user-space with single-copy
* atomicity semantics. This field should only be updated by the
* thread which registered this data structure. Aligned on 64-bit.
*
* 32-bit architectures should update the low order bits of the
* rseq_cs field, leaving the high order bits initialized to 0.
*/
__u64 rseq_cs;
/*
* Restartable sequences flags field.
*
* This field should only be updated by the thread which
* registered this data structure. Read by the kernel.
* Mainly used for single-stepping through rseq critical sections
* with debuggers.
*
* - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
* Inhibit instruction sequence block restart on preemption
* for this thread.
* - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
* Inhibit instruction sequence block restart on signal
* delivery for this thread.
* - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
* Inhibit instruction sequence block restart on migration for
* this thread.
*/
__u32 flags;
} __attribute__((aligned(4 * sizeof(__u64))));
#endif /* _UAPI_LINUX_RSEQ_H */
|
