[PATCH v8 1/3] arm64: mte: make the per-task SCTLR_EL1 field usable elsewhere

[Peter Collingbourne]

On Wed, Apr 14, 2021 at 3:10 AM Catalin Marinas <catalin.marinas at arm.com> wrote:
>
> On Thu, 18 Mar 2021 20:10:52 -0700, Peter Collingbourne wrote:
> > In an upcoming change we are going to introduce per-task SCTLR_EL1
> > bits for PAC. Move the existing per-task SCTLR_EL1 field out of the
> > MTE-specific code so that we will be able to use it from both the
> > PAC and MTE code paths and make the task switching code more efficient.
>
> Applied to arm64 (for-next/pac-set-get-enabled-keys).
>
> Peter, can you please have a look and give it a try as part of the arm64
> for-next/core branch? I rebased your patches on top of the
> for-next/mte-async-kernel-mode branch as this was adding more code to
> mte_thread_switch(), so I kept the function for now.
>
> Thanks.
>
> [1/3] arm64: mte: make the per-task SCTLR_EL1 field usable elsewhere
>       https://git.kernel.org/arm64/c/2f79d2fc391e
> [2/3] arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS)
>       https://git.kernel.org/arm64/c/201698626fbc
> [3/3] arm64: pac: Optimize kernel entry/exit key installation code paths
>       https://git.kernel.org/arm64/c/b90e483938ce

Hi Catalin,

I tested the rebased patch series on an Apple M1 under a hypervisor
with my Android forward-edge PAC prototype and it seems to work.

I think it should be possible to get rid of at least one of the ISBs
that are now on the task switch path, but let's leave that to a later
patch. The patch series looks good otherwise.

Peter