Kernel: Fix all linker errors for Aarch64 build

Author: https://github.com/jamesmintram
Commit: https://github.com/SerenityOS/serenity/commit/ceb33288776
Pull-request: https://github.com/SerenityOS/serenity/pull/10453
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/linusg ✅

Kernel/Arch/aarch64/Processor.h

@@ -61,6 +61,11 @@ public:
     ALWAYS_INLINE static Processor& current() { return *((Processor*)0); }
 
     static void deferred_call_queue(Function<void()> /* callback */) { }
+
+    [[noreturn]] static void halt()
+    {
+        for (;;) { }
+    }
 };
 
 }

Kernel/Arch/aarch64/dummy.cpp

@@ -4,7 +4,79 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/Types.h>
+#include <Kernel/KSyms.h>
+#include <Kernel/Sections.h>
+
+// init.cpp
+extern size_t __stack_chk_guard;
+READONLY_AFTER_INIT size_t __stack_chk_guard;
+
 // This is a temporary file to get a non-empty Kernel binary on aarch64.
 // The prekernel currently never jumps to the kernel. This is dead code.
 void dummy();
 void dummy() { }
+
+// Assertions.h
+[[noreturn]] void __assertion_failed(const char*, const char*, unsigned, const char*);
+
+[[noreturn]] void __assertion_failed(const char*, const char*, unsigned, const char*)
+{
+    for (;;) { }
+}
+
+// kmalloc.h
+size_t kmalloc_good_size(size_t);
+size_t kmalloc_good_size(size_t) { return 0; }
+
+void kfree_sized(void*, size_t);
+void kfree_sized(void*, size_t) { }
+
+void* kmalloc(size_t);
+void* kmalloc(size_t) { return nullptr; }
+
+void* operator new(size_t size) { return kmalloc(size); }
+void* operator new(size_t size, std::align_val_t) { return kmalloc(size); }
+
+namespace Kernel {
+void dump_backtrace(PrintToScreen) { }
+}
+
+extern "C" {
+
+// StdLib.cpp
+[[noreturn]] void __stack_chk_fail();
+[[noreturn]] void __stack_chk_fail()
+{
+    for (;;) { }
+}
+
+int memcmp(const void*, const void*, size_t);
+int memcmp(const void*, const void*, size_t) { return 0; }
+
+int strcmp(char const*, const char*);
+int strcmp(char const*, const char*) { return 0; }
+
+// kstdio.h
+void kernelputstr(const char*, size_t);
+void kernelputstr(const char*, size_t) { }
+
+void kernelcriticalputstr(const char*, size_t);
+void kernelcriticalputstr(const char*, size_t) { }
+
+void kernelearlyputstr(const char*, size_t);
+void kernelearlyputstr(const char*, size_t) { }
+
+// MiniStdLib.cpp
+void* memcpy(void*, const void*, size_t);
+void* memcpy(void*, const void*, size_t) { return nullptr; }
+
+void* memmove(void*, const void*, size_t);
+void* memmove(void*, const void*, size_t) { return nullptr; }
+
+void* memset(void*, int, size_t);
+void* memset(void*, int, size_t) { return nullptr; }
+
+size_t strlen(const char*);
+size_t strlen(const char*) { return 0; }
+}

Kernel/CMakeLists.txt

@@ -361,6 +361,9 @@ else()
         Arch/aarch64/dummy.cpp
         ${AK_SOURCES}
     )
+
+    # Otherwise linker errors e.g undefined reference to `__aarch64_cas8_acq_rel'
+    add_compile_options(-mno-outline-atomics)
 endif()
 
 add_compile_options(-fsigned-char)