From: David Woodhouse <[email protected]> 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 <[email protected]> --- Documentation/filesystems/sysfs-pci.txt | 4 ++++ arch/ia64/include/asm/pci.h | 2 ++ arch/powerpc/include/asm/pci.h | 5 +++-- arch/x86/include/asm/pci.h | 2 ++ drivers/pci/pci-sysfs.c | 4 ++-- drivers/pci/proc.c | 15 ++++++++------- include/linux/pci.h | 4 ++++ 7 files changed, 25 insertions(+), 11 deletions(-) diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt index 6ea1ced..25b7f1c 100644 --- a/Documentation/filesystems/sysfs-pci.txt +++ b/Documentation/filesystems/sysfs-pci.txt @@ -117,6 +117,10 @@ code must define HAVE_PCI_MMAP and provide a pci_mmap_page_range function. Platforms are free to only support subsets of the mmap functionality, but useful return codes should be provided. +Platforms which support write-combining maps of PCI resources must define +arch_can_pci_mmap_wc() which shall evaluate to non-zero at runtime when +write-combining is permitted. + Legacy resources are protected by the HAVE_PCI_LEGACY define. Platforms wishing to support legacy functionality should define it and provide pci_legacy_read, pci_legacy_write and pci_mmap_legacy_page_range functions. diff --git a/arch/ia64/include/asm/pci.h b/arch/ia64/include/asm/pci.h index c0835b0..6283758 100644 --- a/arch/ia64/include/asm/pci.h +++ b/arch/ia64/include/asm/pci.h @@ -51,6 +51,8 @@ extern unsigned long ia64_max_iommu_merge_mask; #define PCI_DMA_BUS_IS_PHYS (ia64_max_iommu_merge_mask == ~0UL) #define HAVE_PCI_MMAP +#define arch_can_pci_mmap_wc() 1 + extern int pci_mmap_page_range (struct pci_dev *dev, struct vm_area_struct *vma, enum pci_mmap_state mmap_state, int write_combine); #define HAVE_PCI_LEGACY diff --git a/arch/powerpc/include/asm/pci.h b/arch/powerpc/include/asm/pci.h index 93eded8..b5b68c6 100644 --- a/arch/powerpc/include/asm/pci.h +++ b/arch/powerpc/include/asm/pci.h @@ -81,8 +81,9 @@ struct vm_area_struct; int pci_mmap_page_range(struct pci_dev *pdev, struct vm_area_struct *vma, enum pci_mmap_state mmap_state, int write_combine); -/* Tell drivers/pci/proc.c that we have pci_mmap_page_range() */ -#define HAVE_PCI_MMAP 1 +/* Tell drivers/pci/proc.c that we have pci_mmap_page_range() and it does WC */ +#define HAVE_PCI_MMAP 1 +#define arch_can_pci_mmap_wc() 1 extern int pci_legacy_read(struct pci_bus *bus, loff_t port, u32 *val, size_t count); diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h index 1411dbe..f6e22c2 100644 --- a/arch/x86/include/asm/pci.h +++ b/arch/x86/include/asm/pci.h @@ -7,6 +7,7 @@ #include <linux/string.h> #include <linux/scatterlist.h> #include <asm/io.h> +#include <asm/pat.h> #include <asm/x86_init.h> #ifdef __KERNEL__ @@ -102,6 +103,7 @@ int pcibios_set_irq_routing(struct pci_dev *dev, int pin, int irq); #define HAVE_PCI_MMAP +#define arch_can_pci_mmap_wc() pat_enabled() extern int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma, enum pci_mmap_state mmap_state, int write_combine); diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 7ac258f..7d494bd 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1211,9 +1211,9 @@ static int pci_create_resource_files(struct pci_dev *pdev) retval = pci_create_attr(pdev, i, 0); /* for prefetchable resources, create a WC mappable file */ - if (!retval && pdev->resource[i].flags & IORESOURCE_PREFETCH) + if (!retval && arch_can_pci_mmap_wc() && + pdev->resource[i].flags & IORESOURCE_PREFETCH) retval = pci_create_attr(pdev, i, 1); - if (retval) { pci_remove_resource_files(pdev); return retval; diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index dc8912e..a2aa58a 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; diff --git a/include/linux/pci.h b/include/linux/pci.h index eb3da1a..e614fb4 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1626,6 +1626,10 @@ static inline int pci_get_new_domain_nr(void) { return -ENOSYS; } #include <asm/pci.h> +#ifndef arch_can_pci_mmap_wc +#define arch_can_pci_mmap_wc() 0 +#endif + #ifndef pci_root_bus_fwnode #define pci_root_bus_fwnode(bus) NULL #endif -- 2.9.3
