Re: [PATCH v1 0/4] coresight: etm: Correct (virtual) contextID tracing for namespace

[Suzuki K Poulose]

Hi Leo


On 31/10/2021 14:42, Leo Yan wrote:
> If a profiling program runs in a non-root PID namespace, if CoreSight
> driver enables contextID tracing, it can lead to mismatching issue
> between the context ID in hardware trace data and the allocated PID in
> the non-root namespace.
>
> CoreSight driver has tried to address this issue for the contextID
> related interfaces under sysfs, but it misses other parts: it doesn't
> prevent user to set VMID (virtual contextID) for kernel runs in EL2 with
> VHE, and furthermore, it misses to handle the perf mode when the
> profiling tool (e.g. perf) doesn't run in root PID namespace.
>
> For this reason, this patch series is to correct contextID tracing for
> non-root namespace.
>
> Patch 01 is to use spinlock to protect reading virtual context ID
> comparator.
>
> Patch 02 corrects the virtual contextID tracing for non-root PID
> namespace.
>
> Patch 03/04 are used to fix the contextID tracing for perf mode.
>
> I only verified this patch series on Juno board in the root PID
> namespace and confirmed the patches don't introduce any regression for
> root PID namespace.

I have finished reviewing the set.

Suzuki