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@xxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> arch/arm/kernel/bios32.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> index 17a26c1..b56fa2d 100644
> --- a/arch/arm/kernel/bios32.c
> +++ b/arch/arm/kernel/bios32.c
> @@ -626,21 +626,15 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
> int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
> enum pci_mmap_state mmap_state, int write_combine)
> {
> - struct pci_sys_data *root = dev->sysdata;
> - unsigned long phys;
> -
> - if (mmap_state == pci_mmap_io) {
> + if (mmap_state == pci_mmap_io)
> return -EINVAL;
> - } else {
> - phys = vma->vm_pgoff + (root->mem_offset >> PAGE_SHIFT);
> - }
>
> /*
> * Mark this as IO
> */
> vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
>
> - if (remap_pfn_range(vma, vma->vm_start, phys,
> + if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
> vma->vm_end - vma->vm_start,
> vma->vm_page_prot))
> return -EAGAIN;
> --
> 2.1.2
>
> --
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