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authorNicolas Pitre <nico@fluxnic.net>2010-09-23 00:34:36 +0200
committerNicolas Pitre <nicolas.pitre@linaro.org>2010-10-02 04:31:34 +0200
commit087aaffcdf9c91667c93923fbc05fa8fb6bc7d3a (patch)
treeec94d9fd07baa4802ff0a3a2811ef3c3e1c7f3f3 /arch/arm/mm/mmap.c
parentARM: do not define VMALLOC_END relative to PAGE_OFFSET (diff)
downloadlinux-087aaffcdf9c91667c93923fbc05fa8fb6bc7d3a.tar.xz
linux-087aaffcdf9c91667c93923fbc05fa8fb6bc7d3a.zip
ARM: implement CONFIG_STRICT_DEVMEM by disabling access to RAM via /dev/mem
There are very few legitimate use cases, if any, for directly accessing system RAM through /dev/mem. So let's mimic what they do on x86 and forbid it when CONFIG_STRICT_DEVMEM is turned on. Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Diffstat (limited to 'arch/arm/mm/mmap.c')
-rw-r--r--arch/arm/mm/mmap.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 4f5b39687df5..b0a98305055c 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -144,3 +144,25 @@ int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
return !(pfn + (size >> PAGE_SHIFT) > 0x00100000);
}
+
+#ifdef CONFIG_STRICT_DEVMEM
+
+#include <linux/ioport.h>
+
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain
+ * address is valid. The argument is a physical page number.
+ * We mimic x86 here by disallowing access to system RAM as well as
+ * device-exclusive MMIO regions. This effectively disable read()/write()
+ * on /dev/mem.
+ */
+int devmem_is_allowed(unsigned long pfn)
+{
+ if (iomem_is_exclusive(pfn << PAGE_SHIFT))
+ return 0;
+ if (!page_is_ram(pfn))
+ return 1;
+ return 0;
+}
+
+#endif