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authorArjan van de Ven <arjan@linux.intel.com>2008-10-22 22:55:31 -0400
committerJesse Barnes <jbarnes@virtuousgeek.org>2009-01-07 14:12:32 -0500
commite8de1481fd7126ee9e93d6889da6f00c05e1e019 (patch)
tree3e0e564f6aff2f8f0f66bdf37dc2eb87d6e17cde /arch/x86/mm/init_64.c
parent23616941914917cf25b94789856b5326b68d8ee8 (diff)
resource: allow MMIO exclusivity for device drivers
Device drivers that use pci_request_regions() (and similar APIs) have a reasonable expectation that they are the only ones accessing their device. As part of the e1000e hunt, we were afraid that some userland (X or some bootsplash stuff) was mapping the MMIO region that the driver thought it had exclusively via /dev/mem or via various sysfs resource mappings. This patch adds the option for device drivers to cause their reserved regions to the "banned from /dev/mem use" list, so now both kernel memory and device-exclusive MMIO regions are banned. NOTE: This is only active when CONFIG_STRICT_DEVMEM is set. In addition to the config option, a kernel parameter iomem=relaxed is provided for the cases where developers want to diagnose, in the field, drivers issues from userspace. Reviewed-by: Matthew Wilcox <willy@linux.intel.com> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'arch/x86/mm/init_64.c')
-rw-r--r--arch/x86/mm/init_64.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 54c437e96541..23f68e77ad1f 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -888,6 +888,8 @@ int devmem_is_allowed(unsigned long pagenr)
888{ 888{
889 if (pagenr <= 256) 889 if (pagenr <= 256)
890 return 1; 890 return 1;
891 if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
892 return 0;
891 if (!page_is_ram(pagenr)) 893 if (!page_is_ram(pagenr))
892 return 1; 894 return 1;
893 return 0; 895 return 0;