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

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Message-ID: <a7f46b5f-de62-4c4d-8c98-a8cf8d88ff4d@linux.intel.com>
Date: Mon, 8 Dec 2025 14:11:33 +0800
From: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>
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 12/5/2025 8:16 PM, Peter Zijlstra wrote:
> 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?

Sure.


>