From: Mark Rutland <mark.rutland@arm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Rob Clark <robdclark@chromium.org>,
Rob Clark <robdclark@gmail.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <maxime.ripard@bootlin.com>,
Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>,
Daniel Vetter <daniel@ffwll.ch>,
Allison Randal <allison@lohutok.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arm-kernel@lists.infradead.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] drm: add cache support for arm64
Date: Thu, 8 Aug 2019 11:24:10 +0100 [thread overview]
Message-ID: <20190808102410.GB46901@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <20190808102053.GA46901@lakrids.cambridge.arm.com>
On Thu, Aug 08, 2019 at 11:20:53AM +0100, Mark Rutland wrote:
> On Thu, Aug 08, 2019 at 09:58:27AM +0200, Christoph Hellwig wrote:
> > On Wed, Aug 07, 2019 at 05:49:59PM +0100, Mark Rutland wrote:
> > > For arm64, we can tear down portions of the linear map, but that has to
> > > be done explicitly, and this is only possible when using rodata_full. If
> > > not using rodata_full, it is not possible to dynamically tear down the
> > > cacheable alias.
> >
> > Interesting. For this or next merge window I plan to add support to the
> > generic DMA code to remap pages as uncachable in place based on the
> > openrisc code. Aѕ far as I can tell the requirement for that is
> > basically just that the kernel direct mapping doesn't use PMD or bigger
> > mapping so that it supports changing protection bits on a per-PTE basis.
> > Is that the case with arm64 + rodata_full?
>
> Yes, with the added case that on arm64 we can also have contiguous
> entries at the PTE level, which we also have to disable.
>
> Our kernel page table creation code does that for rodata_full or
> DEBUG_PAGEALLOC. See arch/arm64/mmu.c, in map_mem(), where we pass
> NO_{BLOCK,CONT}_MAPPINGS down to our pagetable creation code.
Whoops, that should be: arch/arm64/mm/mmu.c.
Mark.
next prev parent reply other threads:[~2019-08-08 10:24 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 21:14 [PATCH 1/2] drm: add cache support for arm64 Rob Clark
2019-08-05 21:14 ` [PATCH 2/2] drm/msm: use drm_cache when available Rob Clark
2019-08-06 8:48 ` [PATCH 1/2] drm: add cache support for arm64 Christoph Hellwig
2019-08-06 9:38 ` Daniel Vetter
2019-08-06 11:38 ` Christoph Hellwig
2019-08-06 14:11 ` Rob Clark
2019-08-06 14:34 ` Mark Rutland
2019-08-06 16:31 ` Rob Clark
2019-08-07 12:38 ` Mark Rutland
2019-08-07 16:15 ` Rob Clark
2019-08-07 16:49 ` Mark Rutland
2019-08-07 17:30 ` Rob Clark
2019-08-08 7:59 ` Christoph Hellwig
2019-08-08 16:44 ` Rob Clark
2019-08-09 8:18 ` Christoph Hellwig
2019-08-08 7:58 ` Christoph Hellwig
2019-08-08 10:20 ` Mark Rutland
2019-08-08 10:24 ` Mark Rutland [this message]
2019-08-08 10:32 ` Will Deacon
2019-08-08 7:53 ` Christoph Hellwig
2019-08-06 15:50 ` Christoph Hellwig
2019-08-06 16:23 ` Rob Clark
2019-08-06 16:26 ` Rob Clark
2019-08-07 6:25 ` Christoph Hellwig
2019-08-07 8:48 ` Daniel Vetter
2019-08-08 9:55 ` Christoph Hellwig
2019-08-08 11:58 ` Daniel Vetter
2019-08-09 8:14 ` Christoph Hellwig
2019-08-07 16:09 ` Rob Clark
2019-08-08 10:00 ` Christoph Hellwig
2019-08-08 16:32 ` Rob Clark
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