kernel: add a temporary syscall dispatch system

kernel/syscall.c

@@ -0,0 +1,40 @@
+#include <mango/machine/cpu.h>
+#include <mango/printk.h>
+#include <mango/syscall.h>
+
+kern_status_t sys_exit(int status)
+{
+	printk("sys_exit(%d)", status);
+	while (1) {
+		ml_cpu_pause();
+	}
+	return KERN_UNIMPLEMENTED;
+}
+
+kern_status_t sys_vm_object_create(
+	const char *name,
+	size_t len,
+	enum vm_prot prot,
+	kern_handle_t *out_handle)
+{
+	printk("sys_vm_object_create()");
+	return KERN_UNIMPLEMENTED;
+}
+
+#define SYSCALL_TABLE_ENTRY(id, p) [SYS_##id] = (virt_addr_t)(sys_##p)
+
+static const virt_addr_t syscall_table[] = {
+	SYSCALL_TABLE_ENTRY(EXIT, exit),
+	SYSCALL_TABLE_ENTRY(VM_OBJECT_CREATE, vm_object_create),
+};
+static const size_t syscall_table_count
+	= sizeof syscall_table / sizeof syscall_table[0];
+
+virt_addr_t syscall_get_func(unsigned int sysid)
+{
+	if (sysid >= syscall_table_count) {
+		return 0;
+	}
+
+	return syscall_table[sysid];
+}