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From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Russell King <linux@arm.linux.org.uk>,
	LAKML <linux-arm-kernel@lists.infradead.org>,
	Linux PCI <linux-pci@vger.kernel.org>
Subject: Re: [RFC PATCH v3 2/2] arm: kernel: fix pci_mmap_page_range() offset calculation
Date: Mon, 26 Jan 2015 09:57:57 +0000	[thread overview]
Message-ID: <20150126095757.GB23384@e102568-lin.cambridge.arm.com> (raw)
In-Reply-To: <20150123235911.GG13072@google.com>

On Fri, Jan 23, 2015 at 11:59:11PM +0000, Bjorn Helgaas wrote:
> On Thu, Nov 13, 2014 at 11:19:16AM +0000, Lorenzo Pieralisi wrote:
> > The pci_mmap_page_range() API should be written to expect offset
> > values representing PCI memory resource addresses as seen by user
> > space, through the pci_resource_to_user() API.
> > 
> > ARM relies on the standard implementation of pci_resource_to_user()
> > which actually is an identity map and exports to user space
> > PCI memory resources as they are stored in PCI devices resources
> > structures, which represent CPU physical addresses (fixed-up using
> > BUS to CPU address conversions) not PCI bus addresses.
> > 
> > Therefore, on ARM platforms where the mapping between CPU and BUS
> > address is not a 1:1 the current pci_mmap_page_range() implementation is
> > erroneous, in that an additional shift is applied to an already fixed-up
> > offset passed from userspace.
> > 
> > Hence, this patch removes the mem_offset from the pgoff calculation
> > since the offset as passed from user space already represents the CPU
> > physical address corresponding to the resource to be mapped, ie no
> > additional offset should be applied.
> > 
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Russell King <linux@arm.linux.org.uk>
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> 
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>

Thank you, I will ask Russell to merge it.

Lorenzo


  reply	other threads:[~2015-01-26  9:58 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-13 11:19 [RFC PATCH v3 0/2] Fix procfs PCI resources mmap Lorenzo Pieralisi
2014-11-13 11:19 ` [RFC PATCH v3 1/2] drivers: pci: fix pci_mmap_fits() implementation for procfs mmap Lorenzo Pieralisi
2014-11-21 17:51   ` Bjorn Helgaas
2014-11-25 10:03     ` Lorenzo Pieralisi
2014-11-25 23:10     ` Benjamin Herrenschmidt
2015-01-21 18:44     ` Lorenzo Pieralisi
2015-01-23 23:58       ` Bjorn Helgaas
2014-11-13 11:19 ` [RFC PATCH v3 2/2] arm: kernel: fix pci_mmap_page_range() offset calculation Lorenzo Pieralisi
2015-01-23 23:59   ` Bjorn Helgaas
2015-01-26  9:57     ` Lorenzo Pieralisi [this message]
2014-11-19  9:57 ` [RFC PATCH v3 0/2] Fix procfs PCI resources mmap Lorenzo Pieralisi

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