linux-kernel - Re: [PATCH RESEND v7 00/21] drivers/perf: apple

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAP-5=fVjJyV2eA1aDnk6cqAhJGc9FZVyHhP7-f=1OyWmzxjN8w@mail.gmail.com>
Date: Mon, 16 Jun 2025 03:44:49 -0700
From: Ian Rogers <irogers@...gle.com>
To: Will Deacon <will@...nel.org>
Cc: Nick Chan <towinchenmi@...il.com>, Mark Rutland <mark.rutland@....com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Catalin Marinas <catalin.marinas@....com>, Janne Grunau <j@...nau.net>, 
	Alyssa Rosenzweig <alyssa@...enzweig.io>, Neal Gompa <neal@...pa.dev>, Sven Peter <sven@...nel.org>, 
	Marc Zyngier <maz@...nel.org>, linux-arm-kernel@...ts.infradead.org, 
	linux-perf-users@...r.kernel.org, devicetree@...r.kernel.org, 
	asahi@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH RESEND v7 00/21] drivers/perf: apple_m1: Add Apple A7-A11,
 T2 SoC support

On Mon, Jun 16, 2025 at 3:29 AM Will Deacon <will@...nel.org> wrote:
>
> On Mon, Jun 16, 2025 at 02:36:18AM -0700, Ian Rogers wrote:
> > On Sun, Jun 15, 2025 at 6:32 PM Nick Chan <towinchenmi@...il.com> wrote:
> > >
> > > This series adds support for the CPU PMU in the older Apple A7-A11, T2
> > > SoCs. These PMUs may have a different event layout, less counters, or
> > > deliver their interrupts via IRQ instead of a FIQ. Since some of those
> > > older SoCs support 32-bit EL0, counting for 32-bit EL0 also need to
> > > be enabled by the driver where applicable.
> > >
> > > Patch 1 adds the DT bindings.
> > > Patch 2-7 prepares the driver to allow adding support for those
> > > older SoCs.
> > > Patch 8-12 adds support for the older SoCs.
> > > Patch 13-21 are the DT changes.
> > >
> > > Signed-off-by: Nick Chan <towinchenmi@...il.com>
> >
> > Hi Nick,
> >
> > This is substantial work and it looks good to me. Do you know why
> > there's been little progress on landing these patches? Buggy Apple ARM
> > PMU support in the kernel has led to reworking the perf tool. It seems
> > best that we can have the best drivers possible.
>
> You reworked the perf tool to support these things? Why? These changes
> are targetting chips in old iPhones afaict (as opposed to "Apple Silicon").
> I think that (a) most people don't particularly care about them and (b)
> they're not fully supported _anyway_ because of crazy stuff like [1].

I was meaning that we reworked the perf tool to work around the Apple
ARM PMU driver expecting to work as if it were an uncore rather than a
core PMU driver. More context here:
"[REGRESSION] Perf (userspace) broken on big.LITTLE systems since v6.5"
https://lore.kernel.org/lkml/08f1f185-e259-4014-9ca4-6411d5c1bc65@marcan.st/
But in general it would be nice Apple ARM PMU support were well loved.
I think we went 2 or 3 minor releases with the perf tool not working,
threats of substantial reverts to avoid the PMU driver bug being
exposed, etc.
As for which Apple ARM devices should have perf support, it seems the
more the merrier.

Thanks,
Ian

> Will
>
> [1] https://lore.kernel.org/r/20240909091425.16258-1-towinchenmi@gmail.com