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From: Will Deacon <will@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, cai@redhat.com,
	catalin.marinas@arm.com, elver@google.com, james.morse@arm.com
Subject: Re: [PATCHv3] arm64: initialize per-cpu offsets earlier
Date: Thu, 4 Mar 2021 12:45:11 +0000	[thread overview]
Message-ID: <20210304124510.GA20956@willie-the-truck> (raw)
In-Reply-To: <20210302115335.42135-1-mark.rutland@arm.com>

On Tue, Mar 02, 2021 at 11:53:35AM +0000, Mark Rutland wrote:
> The current initialization of the per-cpu offset register is difficult
> to follow and this initialization is not always early enough for
> upcoming instrumentation with KCSAN, where the instrumentation callbacks
> use the per-cpu offset.
> 
> To make it possible to support KCSAN, and to simplify reasoning about
> early bringup code, let's initialize the per-cpu offset earlier, before
> we run any C code that may consume it. To do so, this patch adds a new
> init_this_cpu_offset() helper that's called before the usual
> primary/secondary start functions. For consistency, this is also used to
> re-initialize the per-cpu offset after the runtime per-cpu areas have
> been allocated (which can change CPU0's offset).

Is this still early enough now that we have the idreg overrides on the
command-line, which are parsed from C code?

Will

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  reply	other threads:[~2021-03-04 12:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-02 11:53 [PATCHv3] arm64: initialize per-cpu offsets earlier Mark Rutland
2021-03-04 12:45 ` Will Deacon [this message]
2021-03-04 13:08   ` Mark Rutland
2021-03-04 13:30     ` Will Deacon
2021-03-04 15:01       ` Mark Rutland

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