Re: [Patch v9 07/10] perf regs: Enable dumping of SIMD registers

["Mi, Dapeng" <dapeng1.mi@linux.intel.com>]

On 7/6/2026 10:55 AM, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] SIMD register decoding logic dynamically probes the host kernel, breaking cross-platform and offline analysis of perf.data files.
> --
>
> commit 2e9a4421bef9edf42fbc7bb3efd49ba82ff3a75d
> Author: Dapeng Mi <dapeng1.mi@linux.intel.com>
>
> perf regs: Enable dumping of SIMD registers
>
> Support dumping of SIMD registers with the new PERF_SAMPLE_REGS_ABI_SIMD
> ABI.
>
> Currently, the XMM, YMM, ZMM, OPMASK, eGPRs, and SSP registers on x86
> platforms are supported with the PERF_SAMPLE_REGS_ABI_SIMD ABI.
>
>> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
>> index 23f694c3f0c98..5768682dc95fc 100644
>> --- a/tools/perf/builtin-script.c
>> +++ b/tools/perf/builtin-script.c
> [ ... ]
>> @@ -719,23 +719,96 @@ static int perf_session__check_output_opt(struct perf_session *session)
> [ ... ]
>> +	for (reg_c = 0; reg_c < 64; reg_c++) {
>> +		if (!regs->nr_vectors)
>> +			break;
>> +		if (intr) {
>> +			perf_intr_simd_reg_class_bitmap_qwords(e_machine, reg_c,
>> +							       &qwords, /*pred=*/false);
>> +		} else {
>> +			perf_user_simd_reg_class_bitmap_qwords(e_machine, reg_c,
>> +							       &qwords, /*pred=*/false);
>> +		}
> [Severity: Medium]
> Could this break offline and cross-platform analysis of perf.data files?
>
> The perf_intr_simd_reg_class_bitmap_qwords() function dynamically probes the
> host kernel via sys_perf_event_open() to determine the SIMD register lengths.
>
> If a user analyzes a perf.data file on a different machine lacking support for
> that specific SIMD ABI (such as a non-x86 architecture or an older kernel),
> would the probe fail and return a length of 0, causing the register names to
> be printed as "unknown"?
>
> This same pattern appears in tools/perf/util/scripting-engines/trace-event-python.c
> and tools/perf/util/session.c.

It's expected. Currently SIMD register sampling doesn't support cross-arch
parsing.


>