linux-kernel - Re: [PATCH v4 03/36] arm64/gcs: Document the ABI for Guarded Control Stacks

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Message-ID: <3985b0d8-e35e-4cd5-a2bd-6a16d7c7e559@sirena.org.uk>
Date:   Tue, 3 Oct 2023 14:38:02 +0100
From:   Mark Brown <broonie@...nel.org>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
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Subject: Re: [PATCH v4 03/36] arm64/gcs: Document the ABI for Guarded Control
 Stacks

On Mon, Oct 02, 2023 at 09:43:25PM +0000, Edgecombe, Rick P wrote:

> If ARM is thinking of doing things differently than x86, you might
> think about how you weight those tradeoffs. Like, it might be silly to
> worry about clone() support if something else ends up breaking
> compatibility majorly. But, it might be worthwhile it you end up going
> to the proposed extremes around signal alt stacks, to maximize
> compatibility

Yeah, I think Catalin's thinking here was that we're quite a way out
from actual hardware so it's much more tractable to fix up callers than
it is for x86 where the hardware is widely available.

> Also then maybe x86 could copy the ARM ABI some day, if it ends up
> chasing the tradeoff people prefer. It probably goes without saying
> that the closer these features behave from the app developer
> perspective, the better. So a different ABI than x86 that also targets
> a mix would be a bit unfortunate. (not the end of the world though)

If nothing else even if we end up being stricter about things it would
be extremely disappointing if we ended up with something where code for
arm64 won't run when built for x86.

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