linux-kernel - [PATCH v2 4/5] powerpc/vdso: Declare constant vars as __ro_after

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Message-Id: <42bc1c04b574f4b7dff3bddc228eff704de72420.1598594308.git.christophe.leroy@csgroup.eu>
Date:   Fri, 28 Aug 2020 05:58:49 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 4/5] powerpc/vdso: Declare constant vars as __ro_after_init

To avoid any risk of modification of vital VDSO variables,
declare them __ro_after_init.

vdso32_kbase and vdso64_kbase could be made 'const', but it would
have high impact on all functions using them as the compiler doesn't
expect const property to be discarded.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/vdso.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index fb393266b9cb..4ad042995ccc 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -38,19 +38,19 @@
 #define VDSO_ALIGNMENT	(1 << 16)
 
 extern char vdso32_start, vdso32_end;
-static unsigned int vdso32_pages;
-static void *vdso32_kbase = &vdso32_start;
-unsigned long vdso32_sigtramp;
-unsigned long vdso32_rt_sigtramp;
+static unsigned int vdso32_pages __ro_after_init;
+static void *vdso32_kbase __ro_after_init = &vdso32_start;
+unsigned long vdso32_sigtramp __ro_after_init;
+unsigned long vdso32_rt_sigtramp __ro_after_init;
 
 extern char vdso64_start, vdso64_end;
-static void *vdso64_kbase = &vdso64_start;
-static unsigned int vdso64_pages;
+static void *vdso64_kbase __ro_after_init = &vdso64_start;
+static unsigned int vdso64_pages __ro_after_init;
 #ifdef CONFIG_PPC64
-unsigned long vdso64_rt_sigtramp;
+unsigned long vdso64_rt_sigtramp __ro_after_init;
 #endif /* CONFIG_PPC64 */
 
-static int vdso_ready;
+static int vdso_ready __ro_after_init;
 
 /*
  * The vdso data page (aka. systemcfg for old ppc64 fans) is here.
-- 
2.25.0