Re: [PATCH V2] AArch64 pauth: Indicate unmasked addresses in backtrace

Tom Tromey
2019-08-08T16:58:53Z

>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:

Pedro> Hmm, I had suggested considering MI in the previous iteration, but
Pedro> I was just thinking of including the "[PAC]" text in the
Pedro> "addr" field. If we're adding a new field, then a few extra
Pedro> things need to be considered:

Pedro> #1 - documentation, both manual and NEWS should mention this new MI field.

Oops, I forgot about this. Sorry about that.

I don't think putting this information into the "addr" field is a good
idea. It's better, IMO, to let MI field names provide the structure,
rather than requiring clients to also parse the values of fields.

I realize MI isn't 100% clean on this topic, but we can still not make
it worse.

Pedro> #2 - calling the attribute "pac" makes it architecture specific.

I don't think this is such a big deal but at the same time any
reasonable name is fine by me.

Pedro> #3 - The MI attribute is called "pac", and its content is
Pedro> literally " [PAC]". I'd find that odd if I were a frontend author:
Pedro> the content is right aligned with a space, making doing anything with
Pedro> it other than appending it to the address text probably look odd,
Pedro> unless you bake in awareness of the attribute's text... If I saw
Pedro> an attribute named "pac", I'd expect it to be a boolean? At the
Pedro> least, the left space should not be part of the field, I think?

I think part of the pain here is an internal constraint, namely that the
CLI ui-out wouldn't know to rewrite the boolean value to something else
here. But perhaps that's something that could just be addressed
directly.

Tom