1/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
2#ifndef _LINUX_RSEQ_H
3#define _LINUX_RSEQ_H
4
5#ifdef CONFIG_RSEQ
6
7#include <linux/preempt.h>
8#include <linux/sched.h>
9
10/*
11 * Map the event mask on the user-space ABI enum rseq_cs_flags
12 * for direct mask checks.
13 */
14enum rseq_event_mask_bits {
15	RSEQ_EVENT_PREEMPT_BIT	= RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT,
16	RSEQ_EVENT_SIGNAL_BIT	= RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT,
17	RSEQ_EVENT_MIGRATE_BIT	= RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT,
18};
19
20enum rseq_event_mask {
21	RSEQ_EVENT_PREEMPT	= (1U << RSEQ_EVENT_PREEMPT_BIT),
22	RSEQ_EVENT_SIGNAL	= (1U << RSEQ_EVENT_SIGNAL_BIT),
23	RSEQ_EVENT_MIGRATE	= (1U << RSEQ_EVENT_MIGRATE_BIT),
24};
25
26static inline void rseq_set_notify_resume(struct task_struct *t)
27{
28	if (t->rseq)
29		set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
30}
31
32void __rseq_handle_notify_resume(struct ksignal *sig, struct pt_regs *regs);
33
34static inline void rseq_handle_notify_resume(struct ksignal *ksig,
35					     struct pt_regs *regs)
36{
37	if (current->rseq)
38		__rseq_handle_notify_resume(ksig, regs);
39}
40
41static inline void rseq_signal_deliver(struct ksignal *ksig,
42				       struct pt_regs *regs)
43{
44	preempt_disable();
45	__set_bit(RSEQ_EVENT_SIGNAL_BIT, &current->rseq_event_mask);
46	preempt_enable();
47	rseq_handle_notify_resume(ksig, regs);
48}
49
50/* rseq_preempt() requires preemption to be disabled. */
51static inline void rseq_preempt(struct task_struct *t)
52{
53	__set_bit(RSEQ_EVENT_PREEMPT_BIT, &t->rseq_event_mask);
54	rseq_set_notify_resume(t);
55}
56
57/* rseq_migrate() requires preemption to be disabled. */
58static inline void rseq_migrate(struct task_struct *t)
59{
60	__set_bit(RSEQ_EVENT_MIGRATE_BIT, &t->rseq_event_mask);
61	rseq_set_notify_resume(t);
62}
63
64/*
65 * If parent process has a registered restartable sequences area, the
66 * child inherits. Unregister rseq for a clone with CLONE_VM set.
67 */
68static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
69{
70	if (clone_flags & CLONE_VM) {
71		t->rseq = NULL;
72		t->rseq_len = 0;
73		t->rseq_sig = 0;
74		t->rseq_event_mask = 0;
75	} else {
76		t->rseq = current->rseq;
77		t->rseq_len = current->rseq_len;
78		t->rseq_sig = current->rseq_sig;
79		t->rseq_event_mask = current->rseq_event_mask;
80	}
81}
82
83static inline void rseq_execve(struct task_struct *t)
84{
85	t->rseq = NULL;
86	t->rseq_len = 0;
87	t->rseq_sig = 0;
88	t->rseq_event_mask = 0;
89}
90
91#else
92
93static inline void rseq_set_notify_resume(struct task_struct *t)
94{
95}
96static inline void rseq_handle_notify_resume(struct ksignal *ksig,
97					     struct pt_regs *regs)
98{
99}
100static inline void rseq_signal_deliver(struct ksignal *ksig,
101				       struct pt_regs *regs)
102{
103}
104static inline void rseq_preempt(struct task_struct *t)
105{
106}
107static inline void rseq_migrate(struct task_struct *t)
108{
109}
110static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
111{
112}
113static inline void rseq_execve(struct task_struct *t)
114{
115}
116
117#endif
118
119#ifdef CONFIG_DEBUG_RSEQ
120
121void rseq_syscall(struct pt_regs *regs);
122
123#else
124
125static inline void rseq_syscall(struct pt_regs *regs)
126{
127}
128
129#endif
130
131#endif /* _LINUX_RSEQ_H */
132