linux-kernel - [PATCH v2] arm: apply more __ro_after

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Message-ID: <20160810214313.GA10337@www.outflux.net>
Date:	Wed, 10 Aug 2016 14:43:13 -0700
From:	Kees Cook <keescook@...omium.org>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	Russell King <linux@...linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: [PATCH v2] arm: apply more __ro_after_init

Guided by grsecurity's analogous __read_only markings in arch/arm,
this applies several uses of __ro_after_init to structures that are
only updated during __init.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
v2:
- drop vector table for now due to FIQ updates, rmk
---
 arch/arm/kernel/cpuidle.c |  2 +-
 arch/arm/kernel/setup.c   | 10 +++++-----
 arch/arm/kernel/smp.c     |  2 +-
 arch/arm/lib/delay.c      |  2 +-
 arch/arm/mm/mmu.c         |  9 ++-------
 5 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c
index a44b268e12e1..d574708ea20c 100644
--- a/arch/arm/kernel/cpuidle.c
+++ b/arch/arm/kernel/cpuidle.c
@@ -19,7 +19,7 @@ extern struct of_cpuidle_method __cpuidle_method_of_table[];
 static const struct of_cpuidle_method __cpuidle_method_of_table_sentinel
 	__used __section(__cpuidle_method_of_table_end);
 
-static struct cpuidle_ops cpuidle_ops[NR_CPUS];
+static struct cpuidle_ops cpuidle_ops[NR_CPUS] __ro_after_init;
 
 /**
  * arm_cpuidle_simple_enter() - a wrapper to cpu_do_idle()
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 7b5350060612..38196e581d0a 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -115,19 +115,19 @@ EXPORT_SYMBOL(elf_hwcap2);
 
 
 #ifdef MULTI_CPU
-struct processor processor __read_mostly;
+struct processor processor __ro_after_init;
 #endif
 #ifdef MULTI_TLB
-struct cpu_tlb_fns cpu_tlb __read_mostly;
+struct cpu_tlb_fns cpu_tlb __ro_after_init;
 #endif
 #ifdef MULTI_USER
-struct cpu_user_fns cpu_user __read_mostly;
+struct cpu_user_fns cpu_user __ro_after_init;
 #endif
 #ifdef MULTI_CACHE
-struct cpu_cache_fns cpu_cache __read_mostly;
+struct cpu_cache_fns cpu_cache __ro_after_init;
 #endif
 #ifdef CONFIG_OUTER_CACHE
-struct outer_cache_fns outer_cache __read_mostly;
+struct outer_cache_fns outer_cache __ro_after_init;
 EXPORT_SYMBOL(outer_cache);
 #endif
 
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 861521606c6d..937c8920d741 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -82,7 +82,7 @@ enum ipi_msg_type {
 
 static DECLARE_COMPLETION(cpu_running);
 
-static struct smp_operations smp_ops;
+static struct smp_operations smp_ops __ro_after_init;
 
 void __init smp_set_ops(const struct smp_operations *ops)
 {
diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c
index 8044591dca72..2cef11884857 100644
--- a/arch/arm/lib/delay.c
+++ b/arch/arm/lib/delay.c
@@ -29,7 +29,7 @@
 /*
  * Default to the loop-based delay implementation.
  */
-struct arm_delay_ops arm_delay_ops = {
+struct arm_delay_ops arm_delay_ops __ro_after_init = {
 	.delay		= __loop_delay,
 	.const_udelay	= __loop_const_udelay,
 	.udelay		= __loop_udelay,
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 62f4d01941f7..5e2acc78175e 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -243,7 +243,7 @@ __setup("noalign", noalign_setup);
 #define PROT_PTE_S2_DEVICE	PROT_PTE_DEVICE
 #define PROT_SECT_DEVICE	PMD_TYPE_SECT|PMD_SECT_AP_WRITE
 
-static struct mem_type mem_types[] = {
+static struct mem_type mem_types[] __ro_after_init = {
 	[MT_DEVICE] = {		  /* Strongly ordered / ARMv6 shared device */
 		.prot_pte	= PROT_PTE_DEVICE | L_PTE_MT_DEV_SHARED |
 				  L_PTE_SHARED,
 
-- 
2.7.4


-- 
Kees Cook
Nexus Security