archinfo.arch_arm.is_arm_arch returns False for AArch64

[LukeSerne]

Description

The function archinfo.arch_arm.is_arm_arch returns False for archinfo.ArchAArch64:

>>> import archinfo
>>> archinfo.arch_arm.is_arm_arch(archinfo.ArchAArch64)
False

The implementation of is_arm_arch (also) checks if the name string starts with "AArch". However, archinfo.ArchAArch64.name is "AARCH64". In fact, there is no arch that has a name that starts with "AArch". As such, I assume this is a bug - either in is_arm_arch or in the definition of archinfo.ArchAArch64.name.

Possible fix

A possible fix could be to change the implementation of is_arm_arch slightly to:

def is_arm_arch(a):
    return a.name.startswith('ARM') or a.name.startswith('AARCH')

[rhelmot]

oops!!!!!

I would really rather the aarch64 arch be AArch, but it's too late for that I guess!

[rhelmot]

It looks like the above commit causes several of our tests to fail. I'm going to revert it until I have time to investigate.

[ltfish]

Hi all, I believe there is some logic in angr that relies on “AArch64 not being ARM.” I’ve been writing code with the understanding that is_arm_arch() is testing if the architecture is an ARM 32-bit architecture, because, obviously, AArch64 has a lot of differences than ARM 32.

[LukeSerne]

In that case, it might be better to just change the implementation to the below. It doesn't change functionality, so all tests should be unaffected, but it's not suggesting it returns True for AArch64.

def is_arm_arch(a):
    return a.name.startswith('ARM')

[rhelmot]

I've applied the recommended patch. Thanks!