linux-kernel - Re: [PATCH 13/20] perf/x86/intel: Add SSP register support for arch-PEBS

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Message-ID: <4b66b490-3931-4e3d-9968-cd9de04a6b1a@linux.intel.com>
Date: Mon, 27 Jan 2025 10:38:19 -0500
From: "Liang, Kan" <kan.liang@...ux.intel.com>
To: Andi Kleen <ak@...ux.intel.com>, Dapeng Mi <dapeng1.mi@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Eranian Stephane <eranian@...gle.com>, linux-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org, Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [PATCH 13/20] perf/x86/intel: Add SSP register support for
 arch-PEBS



On 2025-01-24 12:16 a.m., Andi Kleen wrote:
>> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
>> index f40b03adb5c7..7ed80f01f15d 100644
>> --- a/arch/x86/events/core.c
>> +++ b/arch/x86/events/core.c
>> @@ -646,6 +646,16 @@ int x86_pmu_hw_config(struct perf_event *event)
>>  			return -EINVAL;
>>  	}
>>  
>> +	/* sample_regs_user never support SSP register. */
>> +	if (unlikely(event->attr.sample_regs_user & BIT_ULL(PERF_REG_X86_SSP)))
>> +		return -EINVAL;
> 
> Why not? It's somewhere.

The current REGS_USER only returns the registers in the struct pt_regs.
The ssp is not part of it. So it is only supported in the REGS_INTR. Is
it enough?

If we want to support ssp with REGS_USER, I think a arch-specific
function should be required early to avoid the perf_sample_regs_user().

Thanks,
Kan