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authorArjan van de Ven <arjan@linux.intel.com>2008-10-23 02:55:31 (GMT)
committerJesse Barnes <jbarnes@virtuousgeek.org>2009-01-07 19:12:32 (GMT)
commite8de1481fd7126ee9e93d6889da6f00c05e1e019 (patch)
tree3e0e564f6aff2f8f0f66bdf37dc2eb87d6e17cde /arch/x86
parent23616941914917cf25b94789856b5326b68d8ee8 (diff)
downloadlinux-e8de1481fd7126ee9e93d6889da6f00c05e1e019.tar.xz
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')
-rw-r--r--arch/x86/mm/init_32.c2
-rw-r--r--arch/x86/mm/init_64.c2
2 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 544d724..88f1b10 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -328,6 +328,8 @@ int devmem_is_allowed(unsigned long pagenr)
{
if (pagenr <= 256)
return 1;
+ if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
+ return 0;
if (!page_is_ram(pagenr))
return 1;
return 0;
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 54c437e..23f68e7 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)
{
if (pagenr <= 256)
return 1;
+ if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
+ return 0;
if (!page_is_ram(pagenr))
return 1;
return 0;