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

[sashiko-bot@kernel.org]

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.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260706023444.3067660-1-dapeng1.mi@linux.intel.com?part=7