How to compile and run "hello world" program for ARM architectures on Gem5?

Question

I have compile the "hello.c" file (in directory: tests/test-progs/hello/src) like this:

aarch64-linux-gun-gcc hello.c -o hello -static

and run gem5:

./build/ARM/gem5.debug configs/example/se.py -c tests/test-progs/hello/src/hello

then, I found this error:

panic: Attempted to execute unimplemented instructions 'mrs' (inst 0x4d5380000)

It shows that the mrs inst is not implemented in gem5.

Totally, I have three questions as follows:

Question 1: In order to run hello program for ARM architecture, how to compile the hello source file to avoid "mrs" insts ?

Question 2: How can I know whether the instruction A has been implemented in gem5 or not for ARM architecture ?

Question 3: If I choose armclang compiler, the error is:

    panic: Attempted to execute unimplemented instructions 'hlt' (inst 0x4d45e0000)

        So how to compile hello to avoid generating "hlt" ?