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 */ set_notify_resume(struct task_struct * task)21 static inline void set_notify_resume(struct task_struct *task) 22 { 23 if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME)) 24 kick_process(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 */ resume_user_mode_work(struct pt_regs * regs)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