Tests+Userland: Implement AARCH64 support for some inline assembly blobs

Author: https://github.com/gunnarbeutner
Commit: https://github.com/SerenityOS/serenity/commit/808c43312d
Pull-request: https://github.com/SerenityOS/serenity/pull/15558
Reviewed-by: https://github.com/BertalanD
Reviewed-by: https://github.com/FireFox317
Reviewed-by: https://github.com/awesomekling ✅
Reviewed-by: https://github.com/linusg

Tests/Kernel/elf-symbolication-kernel-read-exploit.cpp

@@ -11,9 +11,17 @@
 #include <string.h>
 #include <unistd.h>
 
+#if ARCH(I386) || ARCH(X86_64)
 asm("haxcode:\n"
     "1: jmp 1b\n"
     "haxcode_end:\n");
+#elif ARCH(AARCH64)
+asm("haxcode:\n"
+    "1: b 1b\n"
+    "haxcode_end:\n");
+#else
+#    error Unknown architecture
+#endif
 
 extern "C" void haxcode();
 extern "C" void haxcode_end();

Userland/DynamicLoader/main.cpp

@@ -62,9 +62,14 @@ void _entry(int, char**, char**) __attribute__((used));
 
 NAKED void _start(int, char**, char**)
 {
+#ifdef AK_ARCH_AARCH64
+    asm(
+        "bl _entry\n");
+#else
     asm(
         "push $0\n"
         "jmp _entry@plt\n");
+#endif
 }
 
 void _entry(int argc, char** argv, char** envp)

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

@@ -17,3 +17,10 @@ _longjmp:
 longjmp:
     # FIXME: Possibly incomplete.
     ret
+
+.global _sigsetjmp
+.global sigsetjmp
+_sigsetjmp:
+sigsetjmp:
+    # FIXME: Possibly incomplete.
+    ret

Userland/Libraries/LibC/crt0.cpp

@@ -25,9 +25,14 @@ void _start(int, char**, char**) __attribute__((used));
 
 NAKED void _start(int, char**, char**)
 {
+#    ifdef AK_ARCH_AARCH64
+    asm(
+        "bl _entry\n");
+#    else
     asm(
         "push $0\n"
         "jmp _entry@plt\n");
+#    endif
 }
 
 int _entry(int argc, char** argv, char** env)