CMake: Let `Meta/serenity.sh run aarch64` make it past cmake

This adds just enough scaffolding to make cmake succeed.
The build falls over immediately.

CMakeLists.txt

@@ -289,7 +289,7 @@ add_link_options(LINKER:-z,text)
 
 if("${SERENITY_ARCH}" STREQUAL "i686")
     add_compile_options(-march=i686)
-else()
+elseif("${SERENITY_ARCH}" STREQUAL "x86_64")
     add_compile_options(-march=x86-64)
 endif()
 

Kernel/CMakeLists.txt

@@ -5,7 +5,9 @@ else()
     add_compile_options(-Os)
 endif()
 
-if ("${SERENITY_ARCH}" STREQUAL "i686")
+if ("${SERENITY_ARCH}" STREQUAL "aarch64")
+    set(KERNEL_ARCH aarch64)
+elseif ("${SERENITY_ARCH}" STREQUAL "i686")
     set(KERNEL_ARCH i386)
 elseif("${SERENITY_ARCH}" STREQUAL "x86_64")
     set(KERNEL_ARCH x86_64)
@@ -283,24 +285,26 @@ set(KERNEL_SOURCES
     kprintf.cpp
 )
 
-set(KERNEL_SOURCES
-    ${KERNEL_SOURCES}
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/ASM_wrapper.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/Boot/ap_setup.S
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/InterruptEntry.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/Processor.cpp
-)
+if ("${SERENITY_ARCH}" STREQUAL "i686" OR "${SERENITY_ARCH}" STREQUAL "x86_64")
+    set(KERNEL_SOURCES
+        ${KERNEL_SOURCES}
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/ASM_wrapper.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/Boot/ap_setup.S
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/InterruptEntry.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/Processor.cpp
+    )
 
-set(KERNEL_SOURCES
-    ${KERNEL_SOURCES}
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/ASM_wrapper.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/CPU.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/Interrupts.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/Processor.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/ProcessorInfo.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/SafeMem.cpp
-    ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/TrapFrame.cpp
-)
+    set(KERNEL_SOURCES
+        ${KERNEL_SOURCES}
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/ASM_wrapper.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/CPU.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/Interrupts.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/Processor.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/ProcessorInfo.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/SafeMem.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/TrapFrame.cpp
+    )
+endif()
 
 set(AK_SOURCES
     ../AK/FlyString.cpp
@@ -351,7 +355,11 @@ set(SOURCES
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unknown-warning-option -Wvla -Wnull-dereference")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-rtti -ffreestanding -fbuiltin")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mno-80387 -mno-mmx -mno-sse -mno-sse2")
+
+if ("${SERENITY_ARCH}" STREQUAL "i686" OR "${SERENITY_ARCH}" STREQUAL "x86_64")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mno-80387 -mno-mmx -mno-sse -mno-sse2")
+endif()
+
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-asynchronous-unwind-tables")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fstack-protector-strong")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions")
@@ -508,5 +516,7 @@ install(FILES "${CMAKE_CURRENT_BINARY_DIR}/kernel.map" DESTINATION res)
 serenity_install_headers(Kernel)
 serenity_install_sources(Kernel)
 
-add_subdirectory(Prekernel)
+if (NOT "${SERENITY_ARCH}" STREQUAL "aarch64")
+    add_subdirectory(Prekernel)
+endif()
 add_subdirectory(Modules)

Userland/DynamicLoader/CMakeLists.txt

@@ -8,7 +8,10 @@ file(GLOB ELF_SOURCES "../Libraries/LibELF/*.cpp")
 file(GLOB LIBC_SOURCES1 "../Libraries/LibC/*.cpp")
 file(GLOB LIBC_SOURCES2 "../Libraries/LibC/*/*.cpp")
 
-if ("${SERENITY_ARCH}" STREQUAL "i686")
+if ("${SERENITY_ARCH}" STREQUAL "aarch64")
+    file(GLOB LIBC_SOURCES3 "../Libraries/LibC/arch/aarch64/*.S")
+    set(ELF_SOURCES ${ELF_SOURCES} ../Libraries/LibELF/Arch/aarch64/entry.S ../Libraries/LibELF/Arch/aarch64/plt_trampoline.S)
+elseif ("${SERENITY_ARCH}" STREQUAL "i686")
     file(GLOB LIBC_SOURCES3 "../Libraries/LibC/arch/i386/*.S")
     set(ELF_SOURCES ${ELF_SOURCES} ../Libraries/LibELF/Arch/i386/entry.S ../Libraries/LibELF/Arch/i386/plt_trampoline.S)
 elseif ("${SERENITY_ARCH}" STREQUAL "x86_64")

Userland/Libraries/LibC/CMakeLists.txt

@@ -67,7 +67,12 @@ set(LIBC_SOURCES
 file(GLOB AK_SOURCES CONFIGURE_DEPENDS "../../../AK/*.cpp")
 file(GLOB ELF_SOURCES CONFIGURE_DEPENDS "../LibELF/*.cpp")
 
-if ("${SERENITY_ARCH}" STREQUAL "i686")
+if ("${SERENITY_ARCH}" STREQUAL "aarch64")
+    set(ASM_SOURCES "arch/aarch64/setjmp.S")
+    set(ELF_SOURCES ${ELF_SOURCES} ../LibELF/Arch/aarch64/entry.S ../LibELF/Arch/aarch64/plt_trampoline.S)
+    set(CRTI_SOURCE "arch/aarch64/crti.S")
+    set(CRTN_SOURCE "arch/aarch64/crtn.S")
+elseif ("${SERENITY_ARCH}" STREQUAL "i686")
     set(ASM_SOURCES "arch/i386/setjmp.S")
     set(ELF_SOURCES ${ELF_SOURCES} ../LibELF/Arch/i386/entry.S ../LibELF/Arch/i386/plt_trampoline.S)
     set(CRTI_SOURCE "arch/i386/crti.S")

Userland/Libraries/LibC/arch/aarch64/crti.S

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.section .init, "ax", @progbits
+.p2align 2
+.global _init
+.type _init, @function
+_init:
+    # FIXME: Possibly incomplete.
+    ret
+
+.section .fini, "ax", @progbits
+.p2align 4
+.global _fini
+.type _fini, @function
+_fini:
+    # FIXME: Possibly incomplete.
+    ret

Userland/Libraries/LibC/arch/aarch64/crtn.S

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.section .init, "ax", @progbits
+    # FIXME: Possibly incomplete.
+    ret
+
+.section .fini, "ax", @progbits
+    # FIXME: Possibly incomplete.
+    ret

Userland/Libraries/LibC/arch/aarch64/setjmp.S

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.global setjmp
+setjmp:
+    # FIXME: Possibly incomplete.
+    ret
+
+.global longjmp
+longjmp:
+    # FIXME: Possibly incomplete.
+    ret

Userland/Libraries/LibELF/Arch/aarch64/entry.S

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.globl _invoke_entry
+.hidden _invoke_entry
+.type _invoke_entry,@function
+_invoke_entry: # (argc, argv, envp, entry)
+    # FIXME: Possibly incomplete.
+    ret

Userland/Libraries/LibELF/Arch/aarch64/plt_trampoline.S

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.p2align 4
+.globl _plt_trampoline
+.hidden _plt_trampoline
+.type _plt_trampoline,@function
+_plt_trampoline: # (object, relocation_index)
+    # FIXME: Possibly incomplete.
+    ret