Implement syscalls, hello world from userspace

kernel/syscall/syscall.h

@@ -0,0 +1,81 @@
+#ifndef SYSCALL_SYSCALL_H_
+#define SYSCALL_SYSCALL_H_
+
+#include <stdint.h>
+#include "compiler/attr.h"
+
+#define SYSCALLS_MAX 0xff
+
+#define SYSCALL0(name) \
+  name(UNUSED uint64_t _1, \
+       UNUSED uint64_t _2, \
+       UNUSED uint64_t _3, \
+       UNUSED uint64_t _4, \
+       UNUSED uint64_t _5, \
+       UNUSED uint64_t _6 \
+      )
+
+#define SYSCALL1(name, arg1) \
+  name(uint64_t arg1, \
+       UNUSED uint64_t _2, \
+       UNUSED uint64_t _3, \
+       UNUSED uint64_t _4, \
+       UNUSED uint64_t _5, \
+       UNUSED uint64_t _6 \
+      )
+
+#define SYSCALL2(name, arg1, arg2) \
+  name(uint64_t arg1, \
+       uint64_t arg2, \
+       UNUSED uint64_t _3, \
+       UNUSED uint64_t _4, \
+       UNUSED uint64_t _5, \
+       UNUSED uint64_t _6 \
+      )
+
+#define SYSCALL3(name, arg1, arg2, arg3) \
+  name(uint64_t arg1, \
+       uint64_t arg2, \
+       uint64_t arg3, \
+       UNUSED uint64_t _4, \
+       UNUSED uint64_t _5, \
+       UNUSED uint64_t _6 \
+      )
+
+#define SYSCALL4(name, arg1, arg2, arg3, arg4) \
+  name(uint64_t arg1, \
+       uint64_t arg2, \
+       uint64_t arg3, \
+       uint64_t arg4, \
+       UNUSED uint64_t _5, \
+       UNUSED uint64_t _6 \
+      )
+
+#define SYSCALL5(name, arg1, arg2, arg3, arg4, arg5) \
+  name(uint64_t arg1, \
+       uint64_t arg2, \
+       uint64_t arg3, \
+       uint64_t arg4, \
+       uint64_t arg5, \
+       UNUSED uint64_t _6 \
+      )
+
+#define SYSCALL6(name, arg1, arg2, arg3, arg4, arg5, arg6) \
+  name(uint64_t arg1, \
+       uint64_t arg2, \
+       uint64_t arg3, \
+       uint64_t arg4, \
+       uint64_t arg5, \
+       uint64_t arg6 \
+      )
+
+enum {
+  SYS_DEBUGPRINT  = 1,
+  SYS_QUITPROC    = 2,
+};
+
+typedef int32_t (*SyscallFn)(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t, uint64_t);
+
+extern SyscallFn SYSCALL_TABLE[SYSCALLS_MAX];
+
+#endif // SYSCALL_SYSCALL_H_