No key assignment section in pauthabielf64

[zxombie]

In the arm64e document from Apple there is a description of the keys are assignments [1].

I would be useful if the pauthabielf64 document could do the same so various parts of the system know what to expect from a key, e.g. is it per-thread, shared within a process, or global across all processes.

[1] https://github.com/apple/llvm-project/blob/a63a81bd9911f87a0b5dcd5bdd7ccdda7124af87/clang/docs/PointerAuthentication.rst#key-assignments

[smithp35]

You've managed to catch most of us on holiday (me included). I'll bring this up when I get back in a couple of weeks.

As a general principle the PAuthABI is intended to be a low-level ELF ABI that is suitable for several platforms. There will be higher-level PAuth ABIs that will describe the language mapping (signing schema) for a particular platform. For example one might expect different OS Platforms to make their own choices for that. So I'd expect that we'd have that information but in different (yet to be written) documents.