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authorLinus Torvalds <torvalds@linux-foundation.org>2008-04-25 12:48:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-25 12:48:08 -0700
commitbf16ae250999e76aff0491a362073a552db965fc (patch)
tree9b012f0f4e9cc146648fe8914346452563f999d9 /arch/x86/mm/init_64.c
parent0b79dada976198cb1a4c043068e3b44d5cab2a5a (diff)
parent1526a756fba5b1f2eb5001b8e8de2a0ea1bd2c66 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86-pat
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86-pat: generic: add ioremap_wc() interface wrapper /dev/mem: make promisc the default pat: cleanups x86: PAT use reserve free memtype in mmap of /dev/mem x86: PAT phys_mem_access_prot_allowed for dev/mem mmap x86: PAT avoid aliasing in /dev/mem read/write devmem: add range_is_allowed() check to mmap of /dev/mem x86: introduce /dev/mem restrictions with a config option
Diffstat (limited to 'arch/x86/mm/init_64.c')
-rw-r--r--arch/x86/mm/init_64.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index b798e7b92b1..0cca6266303 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -663,6 +663,26 @@ EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
#endif /* CONFIG_MEMORY_HOTPLUG */
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain address
+ * is valid. The argument is a physical page number.
+ *
+ *
+ * On x86, access has to be given to the first megabyte of ram because that area
+ * contains bios code and data regions used by X and dosemu and similar apps.
+ * Access has to be given to non-kernel-ram areas as well, these contain the PCI
+ * mmio resources as well as potential bios/acpi data regions.
+ */
+int devmem_is_allowed(unsigned long pagenr)
+{
+ if (pagenr <= 256)
+ return 1;
+ if (!page_is_ram(pagenr))
+ return 1;
+ return 0;
+}
+
+
static struct kcore_list kcore_mem, kcore_vmalloc, kcore_kernel,
kcore_modules, kcore_vsyscall;