linux-kernel - Re: [Patch v5 12/19] perf/x86: Enable eGPRs sampling using sample_regs

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Message-ID: <20251205121651.GW2528459@noisy.programming.kicks-ass.net>
Date: Fri, 5 Dec 2025 13:16:51 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Eranian Stephane <eranian@...gle.com>,
	Mark Rutland <mark.rutland@....com>, broonie@...nel.org,
	Ravi Bangoria <ravi.bangoria@....com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, Zide Chen <zide.chen@...el.com>,
	Falcon Thomas <thomas.falcon@...el.com>,
	Dapeng Mi <dapeng1.mi@...el.com>, Xudong Hao <xudong.hao@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [Patch v5 12/19] perf/x86: Enable eGPRs sampling using
 sample_regs_* fields

On Wed, Dec 03, 2025 at 02:54:53PM +0800, Dapeng Mi wrote:
> From: Kan Liang <kan.liang@...ux.intel.com>
> 
> This patch enables sampling of APX eGPRs (R16 ~ R31) via the
> sample_regs_* fields.
> 
> To sample eGPRs, the sample_simd_regs_enabled field must be set. This
> allows the spare space (reclaimed from the original XMM space) in the
> sample_regs_* fields to be used for representing eGPRs.
> 
> The perf_reg_value() function needs to check if the
> PERF_SAMPLE_REGS_ABI_SIMD flag is set first, and then determine whether
> to output eGPRs or legacy XMM registers to userspace.
> 
> The perf_reg_validate() function is enhanced to validate the eGPRs bitmap
> by adding a new argument, "simd_enabled".
> 
> Currently, eGPRs sampling is only supported on the x86_64 architecture, as
> APX is only available on x86_64 platforms.
> 
> Suggested-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> Co-developed-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> ---
>  arch/arm/kernel/perf_regs.c           |  2 +-
>  arch/arm64/kernel/perf_regs.c         |  2 +-
>  arch/csky/kernel/perf_regs.c          |  2 +-
>  arch/loongarch/kernel/perf_regs.c     |  2 +-
>  arch/mips/kernel/perf_regs.c          |  2 +-
>  arch/parisc/kernel/perf_regs.c        |  2 +-
>  arch/powerpc/perf/perf_regs.c         |  2 +-
>  arch/riscv/kernel/perf_regs.c         |  2 +-
>  arch/s390/kernel/perf_regs.c          |  2 +-

Perhaps split out the part where you modify the arch function interface?