Re: [Patch v6 10/22] perf/x86: Enable XMM Register Sampling for Non-PEBS Events

[Chang S. Bae]

On 2/8/2026 11:20 PM, Dapeng Mi wrote:
> This patch supports XMM sampling for non-PEBS events in the `REGS_INTR`

Please avoid "This patch".

...

> +static inline void __x86_pmu_sample_ext_regs(u64 mask)
> +{
> +	struct xregs_state *xsave = per_cpu(ext_regs_buf, smp_processor_id());
> +
> +	if (WARN_ON_ONCE(!xsave))
> +		return;
> +
> +	xsaves_nmi(xsave, mask);
> +}
> +
> +static inline void x86_pmu_update_ext_regs(struct x86_perf_regs *perf_regs,
> +					   struct xregs_state *xsave, u64 bitmap)
> +{
> +	u64 mask;
> +
> +	if (!xsave)
> +		return;
> +
> +	/* Filtered by what XSAVE really gives */
> +	mask = bitmap & xsave->header.xfeatures;
> +
> +	if (mask & XFEATURE_MASK_SSE)
> +		perf_regs->xmm_space = xsave->i387.xmm_space;
> +}
> +
> +static void x86_pmu_sample_extended_regs(struct perf_event *event,
> +					 struct perf_sample_data *data,
> +					 struct pt_regs *regs,
> +					 u64 ignore_mask)
> +{

...

> +
> +	if (intr_mask) {
> +		__x86_pmu_sample_ext_regs(intr_mask);
> +		xsave = per_cpu(ext_regs_buf, smp_processor_id());
> +		x86_pmu_update_ext_regs(perf_regs, xsave, intr_mask);

These three lines appear to just update xcomponent's _pointers_ to an 
xsave storage:

  * Retrieve a per-cpu XSAVE buffer if valid
  * Ensure the component's presence against XSTATE_BV
  * Then, update pointers in pref_regs.

which could be done in a function with more descriptive name. Given 
that, I don't think__x86_pmu_sample_ext_regs() has any point. I don't 
understand x86_pmu_sample_extended_regs() naming, either.