linux-kernel - [PATCH v3] ARM: VDSO: put RO and RO after init objects into proper sections

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Message-ID: <1470989538-2953-1-git-send-email-jszhang@marvell.com>
Date:	Fri, 12 Aug 2016 16:12:18 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	<linux@...linux.org.uk>, <nathan_lynch@...tor.com>,
	<keescook@...omium.org>, <arnd@...db.de>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, Jisheng Zhang <jszhang@...vell.com>
Subject: [PATCH v3] ARM: VDSO: put RO and RO after init objects into proper sections

vdso_data_mapping is never modified, so mark it as const.

vdso_total_pages, vdso_data_page, vdso_text_mapping and cntvct_ok are
initialized by vdso_init(), thereafter are read only.

The fact that they are read only after init makes them candidates for
__ro_after_init declarations.

Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
---

Since v2:
  - include <linux/cache.h> explicitly for __ro_after_init

Since v1:
  - use __ro_after_init instead of __read_mostly
  - apply __ro_after_init for vdso_total_pages and cntvct_ok as well

 arch/arm/kernel/vdso.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index 994e971..bbbffe94 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -17,6 +17,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/cache.h>
 #include <linux/elf.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
@@ -39,7 +40,7 @@
 static struct page **vdso_text_pagelist;
 
 /* Total number of pages needed for the data and text portions of the VDSO. */
-unsigned int vdso_total_pages __read_mostly;
+unsigned int vdso_total_pages __ro_after_init;
 
 /*
  * The VDSO data page.
@@ -47,13 +48,13 @@ unsigned int vdso_total_pages __read_mostly;
 static union vdso_data_store vdso_data_store __page_aligned_data;
 static struct vdso_data *vdso_data = &vdso_data_store.data;
 
-static struct page *vdso_data_page;
-static struct vm_special_mapping vdso_data_mapping = {
+static struct page *vdso_data_page __ro_after_init;
+static const struct vm_special_mapping vdso_data_mapping = {
 	.name = "[vvar]",
 	.pages = &vdso_data_page,
 };
 
-static struct vm_special_mapping vdso_text_mapping = {
+static struct vm_special_mapping vdso_text_mapping __ro_after_init = {
 	.name = "[vdso]",
 };
 
@@ -67,7 +68,7 @@ struct elfinfo {
 /* Cached result of boot-time check for whether the arch timer exists,
  * and if so, whether the virtual counter is useable.
  */
-static bool cntvct_ok __read_mostly;
+static bool cntvct_ok __ro_after_init;
 
 static bool __init cntvct_functional(void)
 {
-- 
2.8.1