[PATCH] sparc32: mm: srmmu: add __ro_after_init to sparc32_cachetlb_ops structures

[PATCH] sparc32: mm: srmmu: add __ro_after_init to sparc32_cachetlb_ops structures

[Bhumika Goyal]

The objects viking_ops, viking_sun4d_smp_ops and smp_cachetlb_ops of
type sparc32_cachetlb_ops are not modified anywhere after getting modified 
in the init functions. Inside init their reference is also stored in a
pointer of type const struct sparc32_cachetlb_ops *. So these structures 
are never modified after init, therefore add __ro_after to the declaration 
of these structures.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
---
Instead of using __ro_after_init for the viking_* structures, should I 
use const by making two copies of these structures with different field values? 

 arch/sparc/mm/srmmu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index c7f2a52..def82f6 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -1444,7 +1444,7 @@ static void poke_viking(void)
 	srmmu_set_mmureg(mreg);
 }
 
-static struct sparc32_cachetlb_ops viking_ops = {
+static struct sparc32_cachetlb_ops viking_ops __ro_after_init = {
 	.cache_all	= viking_flush_cache_all,
 	.cache_mm	= viking_flush_cache_mm,
 	.cache_page	= viking_flush_cache_page,
@@ -1475,7 +1475,7 @@ static void poke_viking(void)
  * flushes going at once will require SMP locking anyways so there's
  * no real value in trying any harder than this.
  */
-static struct sparc32_cachetlb_ops viking_sun4d_smp_ops = {
+static struct sparc32_cachetlb_ops viking_sun4d_smp_ops __ro_after_init = {
 	.cache_all	= viking_flush_cache_all,
 	.cache_mm	= viking_flush_cache_mm,
 	.cache_page	= viking_flush_cache_page,
@@ -1759,7 +1759,7 @@ static void smp_flush_sig_insns(struct mm_struct *mm, unsigned long insn_addr)
 	local_ops->sig_insns(mm, insn_addr);
 }
 
-static struct sparc32_cachetlb_ops smp_cachetlb_ops = {
+static struct sparc32_cachetlb_ops smp_cachetlb_ops __ro_after_init = {
 	.cache_all	= smp_flush_cache_all,
 	.cache_mm	= smp_flush_cache_mm,
 	.cache_page	= smp_flush_cache_page,
-- 
1.9.1

Re: [PATCH] sparc32: mm: srmmu: add __ro_after_init to sparc32_cachetlb_ops structures

[Kees Cook]

On Sat, Jan 14, 2017 at 4:31 AM, Bhumika Goyal <bhumirks@gmail.com> wrote:
> The objects viking_ops, viking_sun4d_smp_ops and smp_cachetlb_ops of
> type sparc32_cachetlb_ops are not modified anywhere after getting modified
> in the init functions. Inside init their reference is also stored in a
> pointer of type const struct sparc32_cachetlb_ops *. So these structures
> are never modified after init, therefore add __ro_after to the declaration
> of these structures.
>
> Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

Yay more ro_after_init! :)

-Kees

> ---
> Instead of using __ro_after_init for the viking_* structures, should I
> use const by making two copies of these structures with different field values?
>
>  arch/sparc/mm/srmmu.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
> index c7f2a52..def82f6 100644
> --- a/arch/sparc/mm/srmmu.c
> +++ b/arch/sparc/mm/srmmu.c
> @@ -1444,7 +1444,7 @@ static void poke_viking(void)
>         srmmu_set_mmureg(mreg);
>  }
>
> -static struct sparc32_cachetlb_ops viking_ops = {
> +static struct sparc32_cachetlb_ops viking_ops __ro_after_init = {
>         .cache_all      = viking_flush_cache_all,
>         .cache_mm       = viking_flush_cache_mm,
>         .cache_page     = viking_flush_cache_page,
> @@ -1475,7 +1475,7 @@ static void poke_viking(void)
>   * flushes going at once will require SMP locking anyways so there's
>   * no real value in trying any harder than this.
>   */
> -static struct sparc32_cachetlb_ops viking_sun4d_smp_ops = {
> +static struct sparc32_cachetlb_ops viking_sun4d_smp_ops __ro_after_init = {
>         .cache_all      = viking_flush_cache_all,
>         .cache_mm       = viking_flush_cache_mm,
>         .cache_page     = viking_flush_cache_page,
> @@ -1759,7 +1759,7 @@ static void smp_flush_sig_insns(struct mm_struct *mm, unsigned long insn_addr)
>         local_ops->sig_insns(mm, insn_addr);
>  }
>
> -static struct sparc32_cachetlb_ops smp_cachetlb_ops = {
> +static struct sparc32_cachetlb_ops smp_cachetlb_ops __ro_after_init = {
>         .cache_all      = smp_flush_cache_all,
>         .cache_mm       = smp_flush_cache_mm,
>         .cache_page     = smp_flush_cache_page,
> --
> 1.9.1
>



-- 
Kees Cook
Nexus Security

Re: [PATCH] sparc32: mm: srmmu: add __ro_after_init to sparc32_cachetlb_ops structures

[David Miller]

From: Bhumika Goyal <bhumirks@gmail.com>
Date: Sat, 14 Jan 2017 18:01:54 +0530

> The objects viking_ops, viking_sun4d_smp_ops and smp_cachetlb_ops of
> type sparc32_cachetlb_ops are not modified anywhere after getting modified 
> in the init functions. Inside init their reference is also stored in a
> pointer of type const struct sparc32_cachetlb_ops *. So these structures 
> are never modified after init, therefore add __ro_after to the declaration 
> of these structures.
> 
> Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>

Applied, thanks.