From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] ARM: decompressor: cover BSS in cache clean and reorder with MMU disable on v7
Date: Sun, 24 Jan 2021 16:18:31 +0000 [thread overview]
Message-ID: <20210124161831.GB1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAMj1kXEc3e64QweYLf=izp2HHk_aQBriSgiY-8d9Hxp3pZ02ug@mail.gmail.com>
On Sun, Jan 24, 2021 at 04:45:14PM +0100, Ard Biesheuvel wrote:
> Fair enough. I don't think we will ever be able to get to the bottom of this.
DDI0406 does say that the data accesses will have a "strongly ordered"
memory type, and that the unexpected cache hit behaviour is
implementation defined. That leaves the door open for different
behaviours at different cache levels in a SoC, especially when each
cache level is designed by a different entity.
So, without a greater understanding of how each level of cache operates
and how they interact with each other, I don't think there's much hope
of knowing definitely what is causing the observed behaviour. Hence, we
agree.
> So on the basis that this patch adds back a full cache
> clean+invalidate that was inadvertently removed by my previous patch,
> I think we should apply this patch. GIven that this change can be
> traced back to commit 401b368caaecdce1cf8f05bab448172752230cb0, we
> should probably include
>
> Fixes: 401b368caaec ("ARM: decompressor: switch to by-VA cache
> maintenance for v7 cores")
>
> Are you on board with that?
Yes, I think that's definitely the commit which introduced this bug.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2021-01-24 16:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-22 15:20 [PATCH] ARM: decompressor: cover BSS in cache clean and reorder with MMU disable on v7 Ard Biesheuvel
2021-01-22 16:13 ` Russell King - ARM Linux admin
2021-01-22 16:32 ` Ard Biesheuvel
2021-01-24 13:35 ` Ard Biesheuvel
2021-01-24 15:21 ` Russell King - ARM Linux admin
2021-01-24 15:45 ` Ard Biesheuvel
2021-01-24 16:18 ` Russell King - ARM Linux admin [this message]
2021-01-24 23:08 ` Russell King - ARM Linux admin
2021-01-25 7:51 ` Ard Biesheuvel
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