linux-kernel - Re: [PATCH 3/3] x86/perf: Assert all platform event flags are within PERF_EVENT_FLAG

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Date:   Tue, 30 Aug 2022 11:00:41 +0100
From:   James Clark <james.clark@....com>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        peterz@...radead.org
Subject: Re: [PATCH 3/3] x86/perf: Assert all platform event flags are within
 PERF_EVENT_FLAG_ARCH



On 29/08/2022 07:55, Anshuman Khandual wrote:
> Ensure all platform specific event flags are within PERF_EVENT_FLAG_ARCH.
> 
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: x86@...nel.org
> Cc: linux-perf-users@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
>  arch/x86/events/amd/core.c |  2 ++
>  arch/x86/events/core.c     | 16 ++++++++++++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
> index 9ac3718410ce..7aee514285ba 100644
> --- a/arch/x86/events/amd/core.c
> +++ b/arch/x86/events/amd/core.c
> @@ -1469,6 +1469,8 @@ __init int amd_pmu_init(void)
>  	else
>  		memcpy(hw_cache_event_ids, amd_hw_cache_event_ids, sizeof(hw_cache_event_ids));
>  
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PAIR);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_AMD_BRS);
>  	return 0;
>  }
>  
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index f969410d0c90..98fe13f50632 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -2083,6 +2083,22 @@ static int __init init_hw_perf_events(void)
>  
>  	pr_info("Performance Events: ");
>  
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_LDLAT);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_ST);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_ST_HSW);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_LD_HSW);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_NA_HSW);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_EXCL);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_DYNAMIC);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_EXCL_ACCT);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_AUTO_RELOAD);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_LARGE_PEBS);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_VIA_PT);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_LBR_SELECT);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_TOPDOWN);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_STLAT);
> +	BUILD_BUG_ON(~PERF_EVENT_FLAG_ARCH & PERF_X86_EVENT_PEBS_LAT_HYBRID);
> +

Hi Anshuman,

You can use static_assert() and then put them in the global scope. If
they're next to the definition of these it will be clearer and easier to
maintain.

Also, I'm assuming that this now causes a build failure, so I would
include the change to expand PERF_EVENT_FLAG_ARCH as the first commit in
the set. That way we can see at least one proposed solution.

Thanks
James

>  	switch (boot_cpu_data.x86_vendor) {
>  	case X86_VENDOR_INTEL:
>  		err = intel_pmu_init();