1 files changed, 93 insertions, 0 deletions
diff --git a/include/linux/futex.h b/include/linux/futex.h
new file mode 100644
index 000000000..b70df27d7
--- /dev/null
+++ b/include/linux/futex.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_FUTEX_H
+#define _LINUX_FUTEX_H
+
+#include <linux/sched.h>
+#include <linux/ktime.h>
+
+#include <uapi/linux/futex.h>
+
+struct inode;
+struct mm_struct;
+struct task_struct;
+
+/*
+ * Futexes are matched on equal values of this key.
+ * The key type depends on whether it's a shared or private mapping.
+ * Don't rearrange members without looking at hash_futex().
+ *
+ * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
+ * We use the two low order bits of offset to tell what is the kind of key :
+ *  00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
+ *       (no reference on an inode or mm)
+ *  01 : Shared futex (PTHREAD_PROCESS_SHARED)
+ *	mapped on a file (reference on the underlying inode)
+ *  10 : Shared futex (PTHREAD_PROCESS_SHARED)
+ *       (but private mapping on an mm, and reference taken on it)
+*/
+
+#define FUT_OFF_INODE    1 /* We set bit 0 if key has a reference on inode */
+#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
+
+union futex_key {
+	struct {
+		u64 i_seq;
+		unsigned long pgoff;
+		unsigned int offset;
+	} shared;
+	struct {
+		union {
+			struct mm_struct *mm;
+			u64 __tmp;
+		};
+		unsigned long address;
+		unsigned int offset;
+	} private;
+	struct {
+		u64 ptr;
+		unsigned long word;
+		unsigned int offset;
+	} both;
+};
+
+#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } }
+
+#ifdef CONFIG_FUTEX
+enum {
+	FUTEX_STATE_OK,
+	FUTEX_STATE_EXITING,
+	FUTEX_STATE_DEAD,
+};
+
+static inline void futex_init_task(struct task_struct *tsk)
+{
+	tsk->robust_list = NULL;
+#ifdef CONFIG_COMPAT
+	tsk->compat_robust_list = NULL;
+#endif
+	INIT_LIST_HEAD(&tsk->pi_state_list);
+	tsk->pi_state_cache = NULL;
+	tsk->futex_state = FUTEX_STATE_OK;
+	mutex_init(&tsk->futex_exit_mutex);
+}
+
+void futex_exit_recursive(struct task_struct *tsk);
+void futex_exit_release(struct task_struct *tsk);
+void futex_exec_release(struct task_struct *tsk);
+
+long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
+	      u32 __user *uaddr2, u32 val2, u32 val3);
+#else
+static inline void futex_init_task(struct task_struct *tsk) { }
+static inline void futex_exit_recursive(struct task_struct *tsk) { }
+static inline void futex_exit_release(struct task_struct *tsk) { }
+static inline void futex_exec_release(struct task_struct *tsk) { }
+static inline long do_futex(u32 __user *uaddr, int op, u32 val,
+			    ktime_t *timeout, u32 __user *uaddr2,
+			    u32 val2, u32 val3)
+{
+	return -EINVAL;
+}
+#endif
+
+#endif