From: Shaokun Zhang <zhangshaokun@hisilicon.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH -next] arm64: perf: Fix hw_event_id check in __armv8_pmuv3_map_event
Date: Mon, 7 Jun 2021 18:39:14 +0800 [thread overview]
Message-ID: <1cd71c4a-594b-8a39-b6f8-01146348a512@hisilicon.com> (raw)
In-Reply-To: <20210607083704.GA97489@C02TD0UTHF1T.local>
Hi Mark,
On 2021/6/7 16:37, Mark Rutland wrote:
> On Mon, Jun 07, 2021 at 03:19:03PM +0800, Shaokun Zhang wrote:
>> Raw event SW_INCR (0x0000) shall be included in this check, so fix it.
>>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
>
> Given that SW_INCR depends on the specific counter used (and userspace
> has no control over this), I don't think that it makes sense to expose
> to userspace, much like CHAIN, so I suspect it's better to update the
> commentary instead.
Indeed, no harm on perf use.
>
> Do you have a need for SW_INCR, or was this found by inspection?
>
By inspection, when I traced some other thing and noticed that the
event 0x0000 was exclusive in the if condition by accident.
Thanks,
Shaokun
> Thanks,
> Mark.
>
>> ---
>> arch/arm64/kernel/perf_event.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
>> index a661010308c0..fa2f60d09e15 100644
>> --- a/arch/arm64/kernel/perf_event.c
>> +++ b/arch/arm64/kernel/perf_event.c
>> @@ -1000,7 +1000,7 @@ static int __armv8_pmuv3_map_event(struct perf_event *event,
>> event->hw.flags |= ARMPMU_EVT_64BIT;
>>
>> /* Only expose micro/arch events supported by this PMU */
>> - if ((hw_event_id > 0) && (hw_event_id < ARMV8_PMUV3_MAX_COMMON_EVENTS)
>> + if ((hw_event_id >= 0) && (hw_event_id < ARMV8_PMUV3_MAX_COMMON_EVENTS)
>> && test_bit(hw_event_id, armpmu->pmceid_bitmap)) {
>> return hw_event_id;
>> }
>> --
>> 2.7.4
>>
> .
>
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prev parent reply other threads:[~2021-06-07 10:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-07 7:19 [PATCH -next] arm64: perf: Fix hw_event_id check in __armv8_pmuv3_map_event Shaokun Zhang
2021-06-07 8:37 ` Mark Rutland
2021-06-07 10:39 ` Shaokun Zhang [this message]
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