ARM: implement support for read-mostly sections

As our SMP implementation uses MESI protocols.  Grouping together data
which is mostly only read together means that we avoid unnecessary
cache line bouncing when this code shares a cache line with other data.

In other words, cache lines associated with read-mostly data are
expected to spend most of their time in shared state.

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/cache.h b/arch/arm/include/asm/cache.h
index 9d6122096fbe..75fe66bc02b4 100644
--- a/arch/arm/include/asm/cache.h
+++ b/arch/arm/include/asm/cache.h
@@ -23,4 +23,6 @@
 #define ARCH_SLAB_MINALIGN 8
 #endif
 
+#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+
 #endif
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index cead8893b46b..1581f6d18cca 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -167,6 +167,7 @@ SECTIONS
 
                 NOSAVE_DATA
                 CACHELINE_ALIGNED_DATA(32)
+                READ_MOSTLY_DATA(32)
 
                 /*
                  * The exception fixup table (might need resorting at runtime)