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| author | Bjorn Helgaas <bhelgaas@google.com> | 2016-06-08 22:46:54 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-08-26 04:14:34 +0300 |
| commit | 98d0dd431123ce37f443b8504c44fdf8d0224bf5 (patch) | |
| tree | daf818810e0d4e69f528f1243aca126a9cffbce6 /drivers/pci/proc.c | |
| parent | 747b82e19c8f1ad17416166df82f63c8f205f303 (diff) | |
| download | linux-98d0dd431123ce37f443b8504c44fdf8d0224bf5.tar.xz | |
PCI: Ignore write combining when mapping I/O port space
commit 3a92c319c44a7bcee9f48dff9d97d001943b54c6 upstream.
PCI exposes files like /proc/bus/pci/00/00.0 in procfs. These files
support operations like this:
ioctl(fd, PCIIOC_MMAP_IS_IO); # request I/O port space
ioctl(fd, PCIIOC_WRITE_COMBINE, 1); # request write-combining
mmap(fd, ...)
Write combining is useful on PCI memory space, but I don't think it makes
sense on PCI I/O port space.
We *could* change proc_bus_pci_ioctl() to make it impossible to set
mmap_state == pci_mmap_io and write_combine at the same time, but that
would break the following sequence, which is currently legal:
mmap(fd, ...) # default is I/O, non-combining
ioctl(fd, PCIIOC_WRITE_COMBINE, 1); # request write-combining
ioctl(fd, PCIIOC_MMAP_IS_MEM); # request memory space
mmap(fd, ...) # get write-combining mapping
Ignore the write-combining flag when mapping I/O port space.
This patch should have no functional effect, based on this analysis of all
implementations of pci_mmap_page_range():
- ia64 mips parisc sh unicore32 x86 do not support mapping of I/O port
space at all.
- arm cris microblaze mn10300 sparc xtensa support mapping of I/O port
space, but ignore the write_combine argument to pci_mmap_page_range().
- powerpc supports mapping of I/O port space and uses write_combine, and
it disables write combining for I/O port space in
__pci_mmap_set_pgprot().
This patch makes it possible to remove __pci_mmap_set_pgprot() from
powerpc, which simplifies that path.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers/pci/proc.c')
| -rw-r--r-- | drivers/pci/proc.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index 3f155e78513f..2408abe4ee8c 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -231,7 +231,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma) { struct pci_dev *dev = PDE_DATA(file_inode(file)); struct pci_filp_private *fpriv = file->private_data; - int i, ret; + int i, ret, write_combine; if (!capable(CAP_SYS_RAWIO)) return -EPERM; @@ -245,9 +245,12 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma) if (i >= PCI_ROM_RESOURCE) return -ENODEV; + if (fpriv->mmap_state == pci_mmap_mem) + write_combine = fpriv->write_combine; + else + write_combine = 0; ret = pci_mmap_page_range(dev, vma, - fpriv->mmap_state, - fpriv->write_combine); + fpriv->mmap_state, write_combine); if (ret < 0) return ret; |