ARM: idmap: add identity mapping usage note

Add a note about the usage of the identity mapping; we do not support accesses outside of the identity map region and kernel image while a CPU is using the identity map. This is because the identity mapping may overwrite vmalloc space, IO mappings, the vectors pages, etc. Acked-by: Will Deacon <[email protected]> Signed-off-by: Russell King <[email protected]>
chewitt · Aug 2, 2014 · c5cc87f · c5cc87f
1 parent 811a240
commit c5cc87f
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
@@ -9,6 +9,11 @@
 #include <asm/sections.h>
 #include <asm/system_info.h>
 
+/*
+ * Note: accesses outside of the kernel image and the identity map area
+ * are not supported on any CPU using the idmap tables as its current
+ * page tables.
+ */
 pgd_t *idmap_pgd;
 phys_addr_t (*arch_virt_to_idmap) (unsigned long x);