From: Thomas Gleixner <tglx@linutronix.de>
To: Max Filippov <jcmvbkbc@gmail.com>, linux-xtensa@linux-xtensa.org
Cc: Chris Zankel <chris@zankel.net>,
linux-kernel@vger.kernel.org, Max Filippov <jcmvbkbc@gmail.com>
Subject: Re: [PATCH v2] xtensa/mm/highmem: Make generic kmap_atomic() work correctly
Date: Mon, 16 Nov 2020 21:16:34 +0100 [thread overview]
Message-ID: <87pn4dxdjx.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201116193253.23875-1-jcmvbkbc@gmail.com>
On Mon, Nov 16 2020 at 11:32, Max Filippov wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> The conversion to the generic kmap_atomic() implementation missed the fact
> that xtensa's fixmap works bottom up while all other implementations work
> top down. There is no real reason why xtensa needs to work that way.
>
> Cure it by:
>
> - Using the generic fix_to_virt()/virt_to_fix() functions which work top
> down
> - Adjusting the mapping defines
> - Using the generic index calculation for the non cache aliasing case
> - Making the cache colour offset reverse so the effective index is correct
>
> While at it, remove the outdated and misleading comment above the fixmap
> enum which originates from the initial copy&pasta of this code from i386.
>
> Reported-by: Max Filippov <jcmvbkbc@gmail.com>
> Fixes: 629ed3f7dad2 ("xtensa/mm/highmem: Switch to generic kmap atomic")
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
> Tested-by: Max Filippov <jcmvbkbc@gmail.com>
> ---
> Changes v1->v2:
> - fix off-by-one error in kmap_idx calculation
Duh. Indeed.
Thanks for following up and helping with this. Much appreciated!
tglx
next prev parent reply other threads:[~2020-11-16 20:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 19:32 [PATCH v2] xtensa/mm/highmem: Make generic kmap_atomic() work correctly Max Filippov
2020-11-16 20:16 ` Thomas Gleixner [this message]
2020-11-16 20:24 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
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