arm64: apply __ro_after_init to some objects

These objects are set during initialization, thereafter are read only.

Previously I only want to mark vdso_pages, vdso_spec, vectors_page and
cpu_ops as __read_mostly from performance point of view. Then inspired
by Kees's patch[1] to apply more __ro_after_init for arm, I think it's
better to mark them as __ro_after_init. What's more, I find some more
objects are also read only after init. So apply __ro_after_init to all
of them.

This patch also removes global vdso_pagelist and tries to clean up
vdso_spec[] assignment code.

[1] http://www.spinics.net/lists/arm-kernel/msg523188.html

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

3 files changed, 7 insertions, 4 deletions

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index f3953decb171..bdacead5b802 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -20,6 +20,7 @@
 #include <linux/gfp.h>
 #include <linux/acpi.h>
 #include <linux/bootmem.h>
+#include <linux/cache.h>
 #include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/genalloc.h>
@@ -30,7 +31,7 @@
 
 #include <asm/cacheflush.h>
 
-static int swiotlb __read_mostly;
+static int swiotlb __ro_after_init;
 
 static pgprot_t __get_dma_pgprot(unsigned long attrs, pgprot_t prot,
                                  bool coherent)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index bbb7ee76e319..251e0824cd82 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -23,6 +23,7 @@
 #include <linux/swap.h>
 #include <linux/init.h>
 #include <linux/bootmem.h>
+#include <linux/cache.h>
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/initrd.h>
@@ -55,8 +56,8 @@
  * executes, which assigns it its actual value. So use a default value
  * that cannot be mistaken for a real physical address.
  */
-s64 memstart_addr __read_mostly = -1;
-phys_addr_t arm64_dma_phys_limit __read_mostly;
+s64 memstart_addr __ro_after_init = -1;
+phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
 #ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 4989948d1feb..e634a0f6d62b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -17,6 +17,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/cache.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
@@ -46,7 +47,7 @@
 
 u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
 
-u64 kimage_voffset __read_mostly;
+u64 kimage_voffset __ro_after_init;
 EXPORT_SYMBOL(kimage_voffset);
 
 /*