user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/options/internal/loongarch64-include/mlibc/arch-defs.hpp

@@ -0,0 +1,12 @@
+#ifndef MLIBC_ARCH_DEFS_HPP
+#define MLIBC_ARCH_DEFS_HPP
+
+#include <stddef.h>
+
+namespace mlibc {
+
+inline constexpr size_t page_size = 0x1000;
+
+} // namespace mlibc
+
+#endif // MLIBC_ARCH_DEFS_HPP

user/include/mlibc/options/internal/loongarch64-include/mlibc/thread.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <stdint.h>
+#include <mlibc/tcb.hpp>
+#include <bits/ensure.h>
+
+namespace mlibc {
+
+inline Tcb *get_current_tcb() {
+	// On LoongArch, the TCB is below the thread pointer.
+	uintptr_t tp = (uintptr_t)__builtin_thread_pointer();
+	auto tcb = reinterpret_cast<Tcb *>(tp - sizeof(Tcb));
+	__ensure(tcb == tcb->selfPointer);
+	return tcb;
+}
+
+inline uintptr_t get_sp() {
+	uintptr_t sp;
+	asm volatile ("move %0, $sp" : "=r"(sp));
+	return sp;
+}
+
+} // namespace mlibc