linux-kernel - Re: [PATCH v3] arm64/arm: arm_pmuv3: perf: Don't truncate 64-bit registers

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Message-ID: <7da3bc32-416f-dc21-85c1-4bd3cc82b1@os.amperecomputing.com>
Date:   Sun, 5 Nov 2023 21:55:31 -0800 (PST)
From:   Ilkka Koskinen <ilkka@...amperecomputing.com>
To:     Marc Zyngier <maz@...nel.org>
cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Ilkka Koskinen <ilkka@...amperecomputing.com>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Zaid Al-Bassam <zalbassam@...gle.com>,
        Reiji Watanabe <reijiw@...gle.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] arm64/arm: arm_pmuv3: perf: Don't truncate 64-bit
 registers



On Fri, 3 Nov 2023, Marc Zyngier wrote:
> On Fri, 03 Nov 2023 06:09:36 +0000,
> Anshuman Khandual <anshuman.khandual@....com> wrote:
>>
>>
>>
>> On 11/3/23 00:00, Ilkka Koskinen wrote:
>>> The driver used to truncate several 64-bit registers such as PMCEID[n]
>>> registers used to describe whether architectural and microarchitectural
>>> events in range 0x4000-0x401f exist. Due to discarding the bits, the
>>> driver made the events invisible, even if they existed.
>>>
>>> Moreover, PMCCFILTR and PMCR registers have additional bits in the upper
>>> 32 bits. This patch makes them available although they aren't currently
>>> used. Finally, functions handling PMXEVCNTR and PMXEVTYPER registers are
>>> removed as they not being used at all.
>>>
>>> Fixes: df29ddf4f04b ("arm64: perf: Abstract system register accesses away")
>>> Reported-by: Carl Worth <carl@...amperecomputing.com>
>>
>> This needs an URL for the original bug report in the following format.
>>
>>     Reported-by: Carl Worth <carl@...amperecomputing.com>
>>     Closes: https://lore.kernel.org/..
>
> A report is not necessarily done in a public list. And yet there is *a
> lot* of value in recognising the reporter of the bug.

Thanks, Marc. That's exactly the case here. Carl reported the bug to me 
internally and, therefore, I can't provide an URL to the bug report.

Cheers, Ilkka

>
>>
>> Otherwise, the following checkpatch warning shows up.
>>
>> WARNING: Reported-by: should be immediately followed by Closes: with a URL to the report
>> #17:
>> Reported-by: Carl Worth <carl@...amperecomputing.com>
>> Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
>
> Checkpatch can say what it wants, but that doesn't make it true.
>
> 	M.
>
> -- 
> Without deviation from the norm, progress is not possible.
>