From: Will Deacon <will@kernel.org>
To: Tuan Phan <tuanphan@amperemail.onmicrosoft.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Tuan Phan <tuanphan@os.amperecomputing.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] driver/perf: Add PMU driver for the ARM DMC-620 memory controller.
Date: Fri, 20 Mar 2020 07:59:04 +0000 [thread overview]
Message-ID: <20200320075904.GA2549@willie-the-truck> (raw)
In-Reply-To: <23AD5E45-15E3-4487-9B0D-0D9554DD9DE8@amperemail.onmicrosoft.com>
On Thu, Mar 19, 2020 at 12:03:43PM -0700, Tuan Phan wrote:
> Please find my comments below.
>
> On Mar 19, 2020, at 8:16 AM, Mark Rutland <[1]mark.rutland@arm.com>
> wrote:
> Hi Tuan,
>
> On Tue, Mar 17, 2020 at 05:29:38PM -0700, Tuan Phan wrote:
>
> DMC-620 PMU supports total 10 counters which each is
> independently programmable to different events and can
> be started and stopped individually.
>
> Looking at the TRM for DMC-620, the PMU registers are not in a separate
> frame from the other DMC control registers, and start at offset 0xA00
> (AKA 2560). I would generally expect that access to the DMC control
> registers was restricted to the secure world; is that not the case on
> your platform?
>
> I ask because if those are not restricted, the Normal world could
> potentially undermine the Secure world through this (e.g. playing with
> training settings, messing with the physical memory map, injecting RAS
> errors). Have you considered this?
>
> => Only PMU registers can be accessed within normal world. I only pass
> PMU registers (offset 0xA00) to kernel so shouldn’t be problem.
Just a stylistic thing since there's been a bit of back-and-forth on this
patch, but please can you fix your email client configuration so that the
replies are threaded properly? '=>' is non-standard and it's pretty
hard to spot in a mass of C code. You can look at
Documentation/process/email-clients.rst for some information about
configuring common clients.
Apologies if this comes across as pedantic, but it makes a surprising
difference in how easy it is to keep up with the thread (at least to me).
Will
next prev parent reply other threads:[~2020-03-20 7:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 0:29 [PATCH] driver/perf: Add PMU driver for the ARM DMC-620 memory controller Tuan Phan
2020-03-18 16:02 ` Jonathan Cameron
2020-03-18 20:23 ` Will Deacon
2020-03-19 1:34 ` Shaokun Zhang
2020-03-19 3:01 ` Tuan Phan
2020-03-19 15:16 ` Mark Rutland
[not found] ` <23AD5E45-15E3-4487-9B0D-0D9554DD9DE8@amperemail.onmicrosoft.com>
2020-03-20 7:59 ` Will Deacon [this message]
2020-03-20 11:25 ` Mark Rutland
[not found] ` <A50AA800-3F65-4761-9BCF-F86A028E107D@amperemail.onmicrosoft.com>
2020-04-01 8:11 ` Will Deacon
2020-04-01 9:52 ` Mark Rutland
2020-04-01 10:27 ` Will Deacon
2020-04-01 11:12 ` Robin Murphy
2020-04-01 11:27 ` Mark Rutland
2020-04-01 11:57 ` Robin Murphy
2020-04-01 11:19 ` Mark Rutland
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