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-rw-r--r--include/linux/resume_user_mode.h64
1 files changed, 64 insertions, 0 deletions
diff --git a/include/linux/resume_user_mode.h b/include/linux/resume_user_mode.h
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+++ b/include/linux/resume_user_mode.h
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+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef LINUX_RESUME_USER_MODE_H
+#define LINUX_RESUME_USER_MODE_H
+
+#include <linux/sched.h>
+#include <linux/task_work.h>
+#include <linux/memcontrol.h>
+#include <linux/blk-cgroup.h>
+
+/**
+ * set_notify_resume - cause resume_user_mode_work() to be called
+ * @task: task that will call resume_user_mode_work()
+ *
+ * Calling this arranges that @task will call resume_user_mode_work()
+ * before returning to user mode. If it's already running in user mode,
+ * it will enter the kernel and call resume_user_mode_work() soon.
+ * If it's blocked, it will not be woken.
+ */
+static inline void set_notify_resume(struct task_struct *task)
+{
+ if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME))
+ kick_process(task);
+}
+
+
+/**
+ * resume_user_mode_work - Perform work before returning to user mode
+ * @regs: user-mode registers of @current task
+ *
+ * This is called when %TIF_NOTIFY_RESUME has been set. Now we are
+ * about to return to user mode, and the user state in @regs can be
+ * inspected or adjusted. The caller in arch code has cleared
+ * %TIF_NOTIFY_RESUME before the call. If the flag gets set again
+ * asynchronously, this will be called again before we return to
+ * user mode.
+ *
+ * Called without locks.
+ */
+static inline void resume_user_mode_work(struct pt_regs *regs)
+{
+ clear_thread_flag(TIF_NOTIFY_RESUME);
+ /*
+ * This barrier pairs with task_work_add()->set_notify_resume() after
+ * hlist_add_head(task->task_works);
+ */
+ smp_mb__after_atomic();
+ if (unlikely(task_work_pending(current)))
+ task_work_run();
+
+#ifdef CONFIG_KEYS_REQUEST_CACHE
+ if (unlikely(current->cached_requested_key)) {
+ key_put(current->cached_requested_key);
+ current->cached_requested_key = NULL;
+ }
+#endif
+
+ mem_cgroup_handle_over_high();
+ blkcg_maybe_throttle_current();
+
+ rseq_handle_notify_resume(NULL, regs);
+}
+
+#endif /* LINUX_RESUME_USER_MODE_H */