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>

1 files changed, 15 insertions, 15 deletions

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 10ad8abe7ec5..6225612f2464 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -18,12 +18,13 @@
  * Author: Will Deacon <will.deacon@arm.com>
  */
 
-#include <linux/kernel.h>
+#include <linux/cache.h>
 #include <linux/clocksource.h>
 #include <linux/elf.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/gfp.h>
+#include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/signal.h>
@@ -37,8 +38,7 @@
 #include <asm/vdso_datapage.h>
 
 extern char vdso_start, vdso_end;
-static unsigned long vdso_pages;
-static struct page **vdso_pagelist;
+static unsigned long vdso_pages __ro_after_init;
 
 /*
  * The vDSO data page.
@@ -53,7 +53,7 @@ struct vdso_data *vdso_data = &vdso_data_store.data;
 /*
  * Create and map the vectors page for AArch32 tasks.
  */
-static struct page *vectors_page[1];
+static struct page *vectors_page[1] __ro_after_init;
 
 static int __init alloc_vectors_page(void)
 {
@@ -110,11 +110,19 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 }
 #endif /* CONFIG_COMPAT */
 
-static struct vm_special_mapping vdso_spec[2];
+static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
+	{
+		.name	= "[vvar]",
+	},
+	{
+		.name	= "[vdso]",
+	},
+};
 
 static int __init vdso_init(void)
 {
 	int i;
+	struct page **vdso_pagelist;
 
 	if (memcmp(&vdso_start, "\177ELF", 4)) {
 		pr_err("vDSO is not a valid ELF object!\n");
@@ -138,16 +146,8 @@ static int __init vdso_init(void)
 	for (i = 0; i < vdso_pages; i++)
 		vdso_pagelist[i + 1] = pfn_to_page(PHYS_PFN(__pa(&vdso_start)) + i);
 
-	/* Populate the special mapping structures */
-	vdso_spec[0] = (struct vm_special_mapping) {
-		.name	= "[vvar]",
-		.pages	= vdso_pagelist,
-	};
-
-	vdso_spec[1] = (struct vm_special_mapping) {
-		.name	= "[vdso]",
-		.pages	= &vdso_pagelist[1],
-	};
+	vdso_spec[0].pages = &vdso_pagelist[0];
+	vdso_spec[1].pages = &vdso_pagelist[1];
 
 	return 0;
 }