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From: Rob Herring <robh@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
	Zachary.Leaf@arm.com, Raphael Gault <raphael.gault@arm.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Itaru Kitayama <itaru.kitayama@gmail.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7 0/9] arm64 userspace counter access support
Date: Mon, 3 May 2021 09:56:37 -0500	[thread overview]
Message-ID: <CAL_JsqJuG+rz6bfnsYAW3fQKq28d_38Qihrb72zB_20L4=gDMg@mail.gmail.com> (raw)
In-Reply-To: <YIxTfKh6/uxvd0Fu@kernel.org>

On Fri, Apr 30, 2021 at 1:59 PM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Mon, Apr 19, 2021 at 10:15:02PM -0500, Rob Herring escreveu:
> > Hi all,
> >
> > Another version of arm64 userspace counter access support. I sent out
> > the libperf bits separately and those are now applied (Thanks!), so this
> > is just the arm64 bits.
> >
> >
> > This originally resurrected Raphael's series[1] to enable userspace counter
> > access on arm64. My previous versions are here[2][3][4][5][6][7]. A git
> > branch is here[8].
>
> Rob, please don't mix kernel patches with tools patches. The kernel
> bits, if arch specific should go via the arch maintainer, core stuff to
> PeterZ/Ingo/bpetkov/tglx, and tooling stuff I'll collect.

Okay, perhaps MAINTAINERS should be updated to reflect that better.

>
> We did it on purpose to avoid any semblance of kernel/tool lockstep.
>
> The kernel changes should not prevent the tooling from working and the
> tooling changes shouldn't require the kernel changes.
>
> Preexisting kernels should work with new tools and vice versa.

The only issue I see here is the userspace access tests will fail if
enabled in libperf for an arch but run on an older kernel without
userspace access support. I could instead skip tests if cap_user_rdpmc
is not set, but then how to test that it is set when it should be? I
suppose checking sysfs 'rdpmc' is one option assuming we end up with
the same file on Arm.

Rob

WARNING: multiple messages have this Message-ID
From: Rob Herring <robh@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	 Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	 Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
	Zachary.Leaf@arm.com,  Raphael Gault <raphael.gault@arm.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	 Namhyung Kim <namhyung@kernel.org>,
	Itaru Kitayama <itaru.kitayama@gmail.com>,
	 linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7 0/9] arm64 userspace counter access support
Date: Mon, 3 May 2021 09:56:37 -0500	[thread overview]
Message-ID: <CAL_JsqJuG+rz6bfnsYAW3fQKq28d_38Qihrb72zB_20L4=gDMg@mail.gmail.com> (raw)
In-Reply-To: <YIxTfKh6/uxvd0Fu@kernel.org>

On Fri, Apr 30, 2021 at 1:59 PM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Mon, Apr 19, 2021 at 10:15:02PM -0500, Rob Herring escreveu:
> > Hi all,
> >
> > Another version of arm64 userspace counter access support. I sent out
> > the libperf bits separately and those are now applied (Thanks!), so this
> > is just the arm64 bits.
> >
> >
> > This originally resurrected Raphael's series[1] to enable userspace counter
> > access on arm64. My previous versions are here[2][3][4][5][6][7]. A git
> > branch is here[8].
>
> Rob, please don't mix kernel patches with tools patches. The kernel
> bits, if arch specific should go via the arch maintainer, core stuff to
> PeterZ/Ingo/bpetkov/tglx, and tooling stuff I'll collect.

Okay, perhaps MAINTAINERS should be updated to reflect that better.

>
> We did it on purpose to avoid any semblance of kernel/tool lockstep.
>
> The kernel changes should not prevent the tooling from working and the
> tooling changes shouldn't require the kernel changes.
>
> Preexisting kernels should work with new tools and vice versa.

The only issue I see here is the userspace access tests will fail if
enabled in libperf for an arch but run on an older kernel without
userspace access support. I could instead skip tests if cap_user_rdpmc
is not set, but then how to test that it is set when it should be? I
suppose checking sysfs 'rdpmc' is one option assuming we end up with
the same file on Arm.

Rob

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-05-03 14:56 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-20  3:15 [PATCH v7 0/9] arm64 userspace counter access support Rob Herring
2021-04-20  3:15 ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 1/9] arm64: Restrict undef hook for cpufeature registers Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 2/9] arm64: pmu: Add function implementation to update event index in userpage Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 3/9] arm64: perf: Enable PMU counter direct access for perf event Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 4/9] drivers/perf: arm_pmu: Export the per_cpu cpu_armpmu Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 5/9] arm64: perf: Add userspace counter access disable switch Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 6/9] libperf: Add arm64 support to perf_mmap__read_self() Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 7/9] perf: arm64: Add test for userspace counter access on heterogeneous systems Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-30 16:46   ` Masayoshi Mizuma
2021-04-30 16:46     ` Masayoshi Mizuma
2021-04-30 18:17     ` Rob Herring
2021-04-30 18:17       ` Rob Herring
2021-04-30 18:20       ` Rob Herring
2021-04-30 18:20         ` Rob Herring
2021-04-30 20:16         ` Masayoshi Mizuma
2021-04-30 20:16           ` Masayoshi Mizuma
2021-05-13  9:05   ` nakamura.shun
2021-05-13  9:05     ` nakamura.shun
2021-05-13 12:37     ` Rob Herring
2021-05-13 12:37       ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 8/9] perf: arm64: Add tests for 32-bit and 64-bit counter size userspace access Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-20  3:15 ` [PATCH v7 9/9] Documentation: arm64: Document PMU counters access from userspace Rob Herring
2021-04-20  3:15   ` Rob Herring
2021-04-30 18:59 ` [PATCH v7 0/9] arm64 userspace counter access support Arnaldo Carvalho de Melo
2021-04-30 18:59   ` Arnaldo Carvalho de Melo
2021-05-03 14:56   ` Rob Herring [this message]
2021-05-03 14:56     ` Rob Herring

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