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1 | /* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ |
2 | #ifndef _UAPI_LINUX_RSEQ_H | |
3 | #define _UAPI_LINUX_RSEQ_H | |
4 | ||
5 | /* | |
6 | * linux/rseq.h | |
7 | * | |
8 | * Restartable sequences system call API | |
9 | * | |
10 | * Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
11 | */ | |
12 | ||
ec9c82e0 MD |
13 | #include <linux/types.h> |
14 | #include <asm/byteorder.h> | |
d7822b1e MD |
15 | |
16 | enum rseq_cpu_id_state { | |
17 | RSEQ_CPU_ID_UNINITIALIZED = -1, | |
18 | RSEQ_CPU_ID_REGISTRATION_FAILED = -2, | |
19 | }; | |
20 | ||
21 | enum rseq_flags { | |
22 | RSEQ_FLAG_UNREGISTER = (1 << 0), | |
23 | }; | |
24 | ||
25 | enum 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 | ||
31 | enum 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 always | |
42 | * contained within a single cache-line. It is usually declared as | |
43 | * link-time constant data. | |
44 | */ | |
45 | struct rseq_cs { | |
46 | /* Version of this structure. */ | |
47 | __u32 version; | |
48 | /* enum rseq_cs_flags */ | |
49 | __u32 flags; | |
e96d7135 | 50 | __u64 start_ip; |
d7822b1e | 51 | /* Offset from start_ip. */ |
e96d7135 MD |
52 | __u64 post_commit_offset; |
53 | __u64 abort_ip; | |
d7822b1e MD |
54 | } __attribute__((aligned(4 * sizeof(__u64)))); |
55 | ||
56 | /* | |
57 | * struct rseq is aligned on 4 * 8 bytes to ensure it is always | |
58 | * contained within a single cache-line. | |
59 | * | |
60 | * A single struct rseq per thread is allowed. | |
61 | */ | |
62 | struct rseq { | |
63 | /* | |
64 | * Restartable sequences cpu_id_start field. Updated by the | |
0fb9a1ab MD |
65 | * kernel. Read by user-space with single-copy atomicity |
66 | * semantics. This field should only be read by the thread which | |
67 | * registered this data structure. Aligned on 32-bit. Always | |
68 | * contains a value in the range of possible CPUs, although the | |
69 | * value may not be the actual current CPU (e.g. if rseq is not | |
70 | * initialized). This CPU number value should always be compared | |
71 | * against the value of the cpu_id field before performing a rseq | |
72 | * commit or returning a value read from a data structure indexed | |
73 | * using the cpu_id_start value. | |
d7822b1e MD |
74 | */ |
75 | __u32 cpu_id_start; | |
76 | /* | |
0fb9a1ab MD |
77 | * Restartable sequences cpu_id field. Updated by the kernel. |
78 | * Read by user-space with single-copy atomicity semantics. This | |
79 | * field should only be read by the thread which registered this | |
80 | * data structure. Aligned on 32-bit. Values | |
81 | * RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED | |
82 | * have a special semantic: the former means "rseq uninitialized", | |
83 | * and latter means "rseq initialization failed". This value is | |
84 | * meant to be read within rseq critical sections and compared | |
85 | * with the cpu_id_start value previously read, before performing | |
86 | * the commit instruction, or read and compared with the | |
87 | * cpu_id_start value before returning a value loaded from a data | |
88 | * structure indexed using the cpu_id_start value. | |
d7822b1e MD |
89 | */ |
90 | __u32 cpu_id; | |
91 | /* | |
92 | * Restartable sequences rseq_cs field. | |
93 | * | |
94 | * Contains NULL when no critical section is active for the current | |
95 | * thread, or holds a pointer to the currently active struct rseq_cs. | |
96 | * | |
97 | * Updated by user-space, which sets the address of the currently | |
98 | * active rseq_cs at the beginning of assembly instruction sequence | |
99 | * block, and set to NULL by the kernel when it restarts an assembly | |
100 | * instruction sequence block, as well as when the kernel detects that | |
101 | * it is preempting or delivering a signal outside of the range | |
102 | * targeted by the rseq_cs. Also needs to be set to NULL by user-space | |
103 | * before reclaiming memory that contains the targeted struct rseq_cs. | |
104 | * | |
0fb9a1ab MD |
105 | * Read and set by the kernel. Set by user-space with single-copy |
106 | * atomicity semantics. This field should only be updated by the | |
107 | * thread which registered this data structure. Aligned on 64-bit. | |
bfdf4e62 MD |
108 | * |
109 | * 32-bit architectures should update the low order bits of the | |
110 | * rseq_cs field, leaving the high order bits initialized to 0. | |
d7822b1e | 111 | */ |
bfdf4e62 | 112 | __u64 rseq_cs; |
ec9c82e0 | 113 | |
d7822b1e | 114 | /* |
0fb9a1ab MD |
115 | * Restartable sequences flags field. |
116 | * | |
117 | * This field should only be updated by the thread which | |
118 | * registered this data structure. Read by the kernel. | |
119 | * Mainly used for single-stepping through rseq critical sections | |
120 | * with debuggers. | |
d7822b1e | 121 | * |
d7822b1e | 122 | * - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT |
0fb9a1ab MD |
123 | * Inhibit instruction sequence block restart on preemption |
124 | * for this thread. | |
d7822b1e | 125 | * - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL |
0fb9a1ab MD |
126 | * Inhibit instruction sequence block restart on signal |
127 | * delivery for this thread. | |
d7822b1e | 128 | * - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE |
0fb9a1ab MD |
129 | * Inhibit instruction sequence block restart on migration for |
130 | * this thread. | |
d7822b1e MD |
131 | */ |
132 | __u32 flags; | |
133 | } __attribute__((aligned(4 * sizeof(__u64)))); | |
134 | ||
135 | #endif /* _UAPI_LINUX_RSEQ_H */ |