Kernel: Move common aarch64 asm functions into kernel folder and NS

Kernel/Arch/aarch64/Aarch64Asm.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2021, James Mintram <me@jamesrm.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <Kernel/Arch/aarch64/Aarch64Registers.h>
+
+namespace Kernel {
+
+[[noreturn]] inline void halt()
+{
+    for (;;) {
+        asm volatile("wfi");
+    }
+}
+
+enum class ExceptionLevel : u8 {
+    EL0 = 0,
+    EL1 = 1,
+    EL2 = 2,
+    EL3 = 3,
+};
+
+inline ExceptionLevel get_current_exception_level()
+{
+    u64 current_exception_level;
+
+    asm("mrs  %[value], CurrentEL"
+        : [value] "=r"(current_exception_level));
+
+    current_exception_level = (current_exception_level >> 2) & 0x3;
+    return static_cast<ExceptionLevel>(current_exception_level);
+}
+
+}

Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.S

@@ -5,14 +5,6 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-.global get_current_exception_level
-.type get_current_exception_level, @function
-get_current_exception_level:
-  mrs x0, CurrentEL
-  lsr x0, x0, #2
-  and x0, x0, #0x3
-  ret
-
 .global wait_cycles
 .type wait_cycles, @function
 wait_cycles:

Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.h

@@ -6,14 +6,6 @@
 
 #pragma once
 
-enum class ExceptionLevel : u8 {
-    EL0 = 0,
-    EL1 = 1,
-    EL2 = 2,
-    EL3 = 3,
-};
-
-extern "C" ExceptionLevel get_current_exception_level();
 extern "C" void wait_cycles(int n);
 
 // CPU initialization functions

Kernel/Prekernel/Arch/aarch64/PrekernelExceptions.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <Kernel/Arch/aarch64/Aarch64Asm.h>
 #include <Kernel/Arch/aarch64/Aarch64Registers.h>
 #include <Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.h>
 #include <Kernel/Prekernel/Arch/aarch64/Prekernel.h>
@@ -81,7 +82,7 @@ static void set_up_el1()
 
 void drop_to_exception_level_1()
 {
-    switch (get_current_exception_level()) {
+    switch (Kernel::get_current_exception_level()) {
     case ExceptionLevel::EL3:
         drop_to_el2();
         [[fallthrough]];

Kernel/Prekernel/Arch/aarch64/init.cpp

@@ -7,6 +7,7 @@
 
 #include <AK/Types.h>
 
+#include <Kernel/Arch/aarch64/Aarch64Asm.h>
 #include <Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.h>
 #include <Kernel/Prekernel/Arch/aarch64/BootPPMParser.h>
 #include <Kernel/Prekernel/Arch/aarch64/Framebuffer.h>
@@ -36,7 +37,7 @@ extern "C" [[noreturn]] void init()
     uart.print_str("\r\n");
 
     uart.print_str("CPU started in: EL");
-    uart.print_num(static_cast<u64>(get_current_exception_level()));
+    uart.print_num(static_cast<u64>(Kernel::get_current_exception_level()));
     uart.print_str("\r\n");
 
     uart.print_str("Drop CPU to EL1\r\n");

Kernel/Prekernel/CMakeLists.txt

@@ -23,6 +23,9 @@ if ("${SERENITY_ARCH}" STREQUAL "aarch64")
         # Assembly
         Arch/aarch64/boot.S
         Arch/aarch64/Aarch64_asm_utils.S
+
+        # Shared with kernel
+        ../Arch/aarch64/Aarch64Asm.cpp
     )
 else()
     set(SOURCES