1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
---|---|
2 | |
3 | #ifndef LINUX_RESUME_USER_MODE_H |
4 | #define LINUX_RESUME_USER_MODE_H |
5 | |
6 | #include <linux/sched.h> |
7 | #include <linux/task_work.h> |
8 | #include <linux/memcontrol.h> |
9 | #include <linux/rseq.h> |
10 | #include <linux/blk-cgroup.h> |
11 | |
12 | /** |
13 | * set_notify_resume - cause resume_user_mode_work() to be called |
14 | * @task: task that will call resume_user_mode_work() |
15 | * |
16 | * Calling this arranges that @task will call resume_user_mode_work() |
17 | * before returning to user mode. If it's already running in user mode, |
18 | * it will enter the kernel and call resume_user_mode_work() soon. |
19 | * If it's blocked, it will not be woken. |
20 | */ |
21 | static inline void set_notify_resume(struct task_struct *task) |
22 | { |
23 | if (!test_and_set_tsk_thread_flag(tsk: task, TIF_NOTIFY_RESUME)) |
24 | kick_process(tsk: task); |
25 | } |
26 | |
27 | |
28 | /** |
29 | * resume_user_mode_work - Perform work before returning to user mode |
30 | * @regs: user-mode registers of @current task |
31 | * |
32 | * This is called when %TIF_NOTIFY_RESUME has been set. Now we are |
33 | * about to return to user mode, and the user state in @regs can be |
34 | * inspected or adjusted. The caller in arch code has cleared |
35 | * %TIF_NOTIFY_RESUME before the call. If the flag gets set again |
36 | * asynchronously, this will be called again before we return to |
37 | * user mode. |
38 | * |
39 | * Called without locks. |
40 | */ |
41 | static inline void resume_user_mode_work(struct pt_regs *regs) |
42 | { |
43 | clear_thread_flag(TIF_NOTIFY_RESUME); |
44 | /* |
45 | * This barrier pairs with task_work_add()->set_notify_resume() after |
46 | * hlist_add_head(task->task_works); |
47 | */ |
48 | smp_mb__after_atomic(); |
49 | if (unlikely(task_work_pending(current))) |
50 | task_work_run(); |
51 | |
52 | #ifdef CONFIG_KEYS_REQUEST_CACHE |
53 | if (unlikely(current->cached_requested_key)) { |
54 | key_put(current->cached_requested_key); |
55 | current->cached_requested_key = NULL; |
56 | } |
57 | #endif |
58 | |
59 | mem_cgroup_handle_over_high(GFP_KERNEL); |
60 | blkcg_maybe_throttle_current(); |
61 | |
62 | rseq_handle_notify_resume(NULL, regs); |
63 | } |
64 | |
65 | #endif /* LINUX_RESUME_USER_MODE_H */ |
66 |