kernel: add futex definitions

kernel/futex.c

@@ -0,0 +1,70 @@
+#include <kernel/address-space.h>
+#include <kernel/futex.h>
+#include <mango/status.h>
+
+enum futex_flags {
+	FUTEX_CREATE = 0x01u,
+};
+
+static struct btree futex_list = {0};
+static spin_lock_t futex_list_lock = SPIN_LOCK_INIT;
+
+static struct vm_cache futex_cache = {
+	.c_name = "futex",
+	.c_obj_size = sizeof(struct futex),
+};
+
+BTREE_DEFINE_SIMPLE_INSERT(struct futex, f_node, f_key, put_futex)
+BTREE_DEFINE_SIMPLE_GET(struct futex, futex_key_t, f_node, f_key, get_futex)
+
+kern_status_t futex_init(void)
+{
+	vm_cache_init(&futex_cache);
+	return KERN_OK;
+}
+
+static struct futex *get_data(futex_key_t key, enum futex_flags flags)
+{
+	spin_lock(&futex_list_lock);
+	struct futex *futex = get_futex(&futex_list, key);
+	spin_unlock(&futex_list_lock);
+
+	if (!futex && !(flags & FUTEX_CREATE)) {
+		return NULL;
+	}
+
+	futex = vm_cache_alloc(&futex_cache, VM_NORMAL);
+	futex->f_key = key;
+
+	spin_lock(&futex_list_lock);
+	put_futex(&futex_list, futex);
+	spin_unlock(&futex_list_lock);
+
+	return futex;
+}
+
+kern_status_t futex_get(
+	struct address_space *space,
+	kern_futex_t *futex,
+	futex_key_t *out)
+{
+	unsigned long flags;
+	address_space_lock_irqsave(space, &flags);
+	kern_status_t status = address_space_translate(
+		space,
+		(virt_addr_t)futex,
+		out,
+		&flags);
+	address_space_unlock_irqrestore(space, flags);
+	return status;
+}
+
+kern_status_t futex_wait(futex_key_t futex, kern_futex_t new_val)
+{
+	return KERN_UNIMPLEMENTED;
+}
+
+kern_status_t futex_wake(futex_key_t futex, size_t nwaiters)
+{
+	return KERN_UNIMPLEMENTED;
+}