[PATCH v2 2/4] arm64/signal: Include TPIDR2 in the signal context

[Mark Brown]

On Fri, Nov 18, 2022 at 07:10:16PM +0000, Catalin Marinas wrote:
> On Fri, Nov 18, 2022 at 01:55:53PM +0000, Will Deacon wrote:

> > So I'd vote for removing the checks from restore_fpsimd_context() which
> > raises the same question we were discussing initially: should the check
> > in parse_user_sigframe() require an exact size match or instead truncate
> > the structure on the stack by only copying a prefix into the kernel?

> > I'm actually warming more towards an exact check now that we've spoken
> > about it a bit... What do you think?

> I'd go for an exact match as well. I don't think we can expand these
> structures in the future safely without an additional magic number.

> I tend to agree with Mark here that parse_user_sigframe() should only
> check the magic numbers and set the corresponding user_ctxs members. We
> leave the exact size check to the restore_fpsimd_context() etc. (can
> skip the magic check here). Well, not a strong view either way but we
> should definitely remove the duplicate checks.

I'm working on this, should have something out in the next day or so,
but it's getting a bit more involved than just a simple fix (the main
thing is that the various frame type parsers aren't consistent in how
they're called which makes things a bit more invasive than they should
be).
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