drsym_lookup_address should not return Arm mapping symbols

Created by: algr

Arm and AArch64 ABIs extend ELF with code mapping symbols to disambiguate code and data (and in the case of AArch32, they disambiguate Arm and Thumb). Symbols are generally $a, $t, $x and $d possibly extended with a suffix .xxxx.

What we are seeing is that diagnostics that call drsym_lookup_address() to find the function containing some address of interest, are (on Arm/Arm64) sometimes finding mapping symbols. This function should ignore mapping symbols. This would give consistent behavior across Arm and non-Arm architectures.

The mapping symbols might be useful for a query like "is this address Arm, Thumb, Arm64 or a literal pool?" but that's a different sort of query.

Basically, the mapping symbols aren't proper symbols, they are just there for technical reasons because that was a way to mark places in ELF - they could equally well have been relocations.

Seen on 9.0.