From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Linux IOMMU <iommu@lists.linux-foundation.org>,
Michal Simek <monstr@monstr.eu>,
ashutosh.dixit@intel.com, alpha <linux-alpha@vger.kernel.org>,
arcml <linux-snps-arc@lists.infradead.org>,
linux-c6x-dev@linux-c6x.org,
linux-m68k <linux-m68k@lists.linux-m68k.org>,
Openrisc <openrisc@lists.librecores.org>,
Parisc List <linux-parisc@vger.kernel.org>,
linux-s390 <linux-s390@vger.kernel.org>,
sparclinux <sparclinux@vger.kernel.org>,
linux-xtensa@linux-xtensa.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] dma-mapping: zero memory returned from dma_alloc_*
Date: Fri, 14 Dec 2018 10:55:27 +0100 [thread overview]
Message-ID: <CAMuHMdXzuS3sEZ1LNxhCiNtvzUneGsfPjMNWSh8UfbGEEnPTRA@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdWOr0EsgFQF8tjJYLxKVXx+Jwn73N8SVKt8AQGLKQ8V-A@mail.gmail.com>
On Fri, Dec 14, 2018 at 10:54 AM Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> On Fri, Dec 14, 2018 at 9:26 AM Christoph Hellwig <hch@lst.de> wrote:
> > If we want to map memory from the DMA allocator to userspace it must be
> > zeroed at allocation time to prevent stale data leaks. We already do
> > this on most common architectures, but some architectures don't do this
> > yet, fix them up, either by passing GFP_ZERO when we use the normal page
> > allocator or doing a manual memset otherwise.
> >
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
>
> Thanks for your patch!
>
> > --- a/arch/m68k/kernel/dma.c
> > +++ b/arch/m68k/kernel/dma.c
> > @@ -32,7 +32,7 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
> > size = PAGE_ALIGN(size);
> > order = get_order(size);
> >
> > - page = alloc_pages(flag, order);
> > + page = alloc_pages(flag | GFP_ZERO, order);
> > if (!page)
> > return NULL;
>
> There's second implementation below, which calls __get_free_pages() and
> does an explicit memset(). As __get_free_pages() calls alloc_pages(), perhaps
> it makes sense to replace the memset() by GFP_ZERO, to increase consistency?
Regardless, for m68k:
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2018-12-14 9:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 8:25 ensure dma_alloc_coherent always returns zeroed memory Christoph Hellwig
2018-12-14 8:25 ` [PATCH 1/2] dma-mapping: zero memory returned from dma_alloc_* Christoph Hellwig
2018-12-14 9:54 ` Geert Uytterhoeven
2018-12-14 9:55 ` Geert Uytterhoeven [this message]
2018-12-14 11:47 ` Christoph Hellwig
2018-12-14 12:36 ` Geert Uytterhoeven
2018-12-14 14:14 ` Greg Ungerer
2018-12-17 11:59 ` Christoph Hellwig
2018-12-14 12:12 ` Eugeniy Paltsev
2018-12-14 12:21 ` hch
2018-12-14 18:10 ` Sam Ravnborg
2018-12-14 18:35 ` Christoph Hellwig
2018-12-14 8:25 ` [PATCH 2/2] dma-mapping: deprecate dma_zalloc_coherent Christoph Hellwig
2018-12-14 13:33 ` ensure dma_alloc_coherent always returns zeroed memory Christoph Hellwig
2018-12-19 16:59 ` Christoph Hellwig
2018-12-20 14:32 ` Eugeniy Paltsev
2018-12-20 14:34 ` hch
2018-12-20 14:39 ` Eugeniy Paltsev
2018-12-20 14:46 ` hch
2018-12-20 17:37 ` hch
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