From ae749c7ab475de2c9c427058db19921c91846e89 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Wed, 12 Apr 2017 13:25:54 +0100 Subject: PCI: Add arch_can_pci_mmap_wc() macro Most of the almost-identical versions of pci_mmap_page_range() silently ignore the 'write_combine' argument and give uncached mappings. Yet we allow the PCIIOC_WRITE_COMBINE ioctl in /proc/bus/pci, expose the 'resourceX_wc' file in sysfs, and allow an attempted mapping to apparently succeed. To fix this, introduce a macro arch_can_pci_mmap_wc() which indicates whether the platform can do a write-combining mapping. On x86 this ends up being pat_enabled(), while the few other platforms that support it can just set it to a literal '1'. Signed-off-by: David Woodhouse Signed-off-by: Bjorn Helgaas --- drivers/pci/proc.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'drivers/pci/proc.c') diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index dc8912e2d4a1..a2aa58a8fb96 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -210,14 +210,15 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd, break; case PCIIOC_WRITE_COMBINE: - if (arg) - fpriv->write_combine = 1; - else - fpriv->write_combine = 0; - break; - + if (arch_can_pci_mmap_wc()) { + if (arg) + fpriv->write_combine = 1; + else + fpriv->write_combine = 0; + break; + } + /* If arch decided it can't, fall through... */ #endif /* HAVE_PCI_MMAP */ - default: ret = -EINVAL; break; -- cgit v1.2.3