From: Will Deacon <will@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org,
Shawn Anastasio <shawn@anastas.io>,
Michael Ellerman <mpe@ellerman.id.au>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dma-mapping: fix page attributes for dma_mmap_*
Date: Thu, 1 Aug 2019 17:23:06 +0100 [thread overview]
Message-ID: <20190801162305.3m32chycsdjmdejk@willie-the-truck> (raw)
In-Reply-To: <20190801142118.21225-2-hch@lst.de>
On Thu, Aug 01, 2019 at 05:21:18PM +0300, Christoph Hellwig wrote:
> All the way back to introducing dma_common_mmap we've defaulyed to mark
> the pages as uncached. But this is wrong for DMA coherent devices or
> if using DMA_ATTR_NON_CONSISTENT. Later on DMA_ATTR_WRITE_COMBINE
> also got incorrect treatment as that flag is only treated special on
> the alloc side for non-coherent devices.
>
> Introduce a new dma_mmap_pgprot helper that deals with the check
> for coherent devices and DMA_ATTR_NON_CONSISTENT so that only the
> remapping cases even reach arch_dma_mmap_pgprot and we thus ensure
> no aliasing of page attributes happens.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> arch/arm/mm/dma-mapping.c | 4 +---
> arch/arm64/mm/dma-mapping.c | 4 +---
> arch/powerpc/kernel/Makefile | 3 +--
> arch/powerpc/kernel/dma-common.c | 17 -----------------
> drivers/iommu/dma-iommu.c | 6 +++---
> include/linux/dma-mapping.h | 1 +
> include/linux/dma-noncoherent.h | 5 -----
> kernel/dma/mapping.c | 11 ++++++++++-
> kernel/dma/remap.c | 2 +-
> 9 files changed, 18 insertions(+), 35 deletions(-)
> delete mode 100644 arch/powerpc/kernel/dma-common.c
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 9c9a23e5600d..cfe44df169c5 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -2397,9 +2397,7 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
> pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
> unsigned long attrs)
> {
> - if (!dev_is_dma_coherent(dev))
> - return __get_dma_pgprot(attrs, prot);
> - return prot;
> + return __get_dma_pgprot(attrs, prot);
> }
>
> void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index 1d3f0b5a9940..bd2b039f43a6 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -14,9 +14,7 @@
> pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
> unsigned long attrs)
> {
> - if (!dev_is_dma_coherent(dev) || (attrs & DMA_ATTR_WRITE_COMBINE))
> - return pgprot_writecombine(prot);
> - return prot;
> + return pgprot_writecombine(prot);
> }
Seems like a sensible cleanup to me:
Acked-by: Will Deacon <will@kernel.org>
Although arch_dma_mmap_pgprot() is a bit of a misnomer now that it only
gets involved in the non-coherent case.
Will
next prev parent reply other threads:[~2019-08-01 16:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 14:21 fix default dma_mmap_* pgprot Christoph Hellwig
2019-08-01 14:21 ` [PATCH] dma-mapping: fix page attributes for dma_mmap_* Christoph Hellwig
2019-08-01 16:23 ` Will Deacon [this message]
2019-08-01 16:34 ` Christoph Hellwig
2019-08-01 16:44 ` Will Deacon
2019-08-02 8:14 ` Christoph Hellwig
2019-08-02 10:38 ` Will Deacon
2019-08-03 6:48 ` Christoph Hellwig
2019-08-06 16:08 ` Will Deacon
2019-08-06 16:45 ` Russell King - ARM Linux admin
2019-08-06 16:48 ` Russell King - ARM Linux admin
2019-08-07 6:14 ` Christoph Hellwig
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