Kernel: We can create basic userspace processes

These are still allocated on the kernel memory

kernel/include/kernel/Process.h

@@ -23,9 +23,10 @@ namespace Kernel
 
 	public:
 		static BAN::ErrorOr<BAN::RefPtr<Process>> create_kernel(entry_t, void*);
+		static BAN::ErrorOr<BAN::RefPtr<Process>> create_userspace(void(*)());
 		~Process();
 
-		void exit();
+		[[noreturn]] void exit();
 
 		BAN::ErrorOr<Thread*> add_thread(entry_t, void*);
 		void on_thread_exit(Thread&);

kernel/include/kernel/Syscall.h

@@ -1,4 +1,20 @@
 #pragma once
 
-#define SYS_TEST 0
-#define SYS_PUTC 1
+#define SYS_EXIT 1
+#define SYS_READ 2
+#define SYS_WRITE 3
+
+#include <stdint.h>
+
+namespace Kernel
+{
+
+	template<typename T1 = void*, typename T2 = void*, typename T3 = void*>
+	inline int syscall(int syscall, T1 arg1 = nullptr, T2 arg2 = nullptr, T3 arg3 = nullptr)
+	{
+		int ret;
+		asm volatile("int $0x80" : "=a"(ret) : "a"(syscall), "b"((uintptr_t)arg1), "c"((uintptr_t)arg2), "d"((uintptr_t)arg3) : "memory");
+		return ret;
+	}
+
+}

kernel/include/kernel/Thread.h

@@ -29,6 +29,8 @@ namespace Kernel
 		static BAN::ErrorOr<Thread*> create(entry_t, void* = nullptr, BAN::RefPtr<Process> = nullptr);
 		~Thread();
 
+		void jump_userspace(uintptr_t rip);
+
 		pid_t tid() const { return m_tid; }
 
 		void set_rsp(uintptr_t rsp) { m_rsp = rsp; }