ARM: 7169/1: topdown mmap support

Similar to other architectures, this adds topdown mmap support in user
process address space allocation policy. This allows mmap sizes greater
than 2GB. This support is largely copied from MIPS and the generic
implementations.

The address space randomization is moved into arch_pick_mmap_layout.

Tested on V-Express with ubuntu and a mmap test from here:
https://bugs.launchpad.net/bugs/861296

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 3 insertions, 0 deletions

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 9451dce3a553..2f659e239727 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -336,6 +336,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
  * We provide our own arch_get_unmapped_area to cope with VIPT caches.
  */
 #define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
 
 /*
  * remap a physical page `pfn' of size `size' with page protection `prot'
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index b2d9df5667af..ce280b8d613c 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -123,6 +123,8 @@ static inline void prefetch(const void *ptr)
 
 #endif
 
+#define HAVE_ARCH_PICK_MMAP_LAYOUT
+
 #endif
 
 #endif /* __ASM_ARM_PROCESSOR_H */