Re: [PATCH v4 1/2] arm64: mte: make the per-task SCTLR_EL1 field usable elsewhere

On Mon, Nov 30, 2020 at 4:51 AM Catalin Marinas [off-list ref] wrote:

Hi Peter,

On Fri, Nov 27, 2020 at 07:13:43PM +0000, Catalin Marinas wrote:

quoted

On Thu, 19 Nov 2020 19:29:46 -0800, Peter Collingbourne wrote:

quoted

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-keys-ctrl), thanks!

[1/2] arm64: mte: make the per-task SCTLR_EL1 field usable elsewhere
      https://git.kernel.org/arm64/c/e710c29e0177
[2/2] arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS)
      https://git.kernel.org/arm64/c/284c64e9eba3

If Dave has any other comments next week, we can apply them on top.

I'm dropping these patches from the arm64 tree as they conflict
(and not in a trivial way) with the MTE patches queued in the mm tree.

So we either wait until 5.12 or we try to merge them via Andrew on top
of the mm tree. Given the interaction with MTE, I'm slightly inclined
towards the former.

Okay, I don't mind waiting until 5.12.

In the process of resolving the conflict I happened to notice a couple
of minor bugs (one in your original MTE patch series and one in this
patch). I sent a patch to fix the former and v5 of this series to
resolve the conflicts and fix the latter.

I also took the opportunity to do some perf measurements with the real
instruction sequences now that I have access to capable hardware, and
I included the results in the commit message.

Peter