* [PATCH] ARM: VDSO: put read only/mostly objects into proper sections
@ 2016-08-10 9:09 Jisheng Zhang
2016-08-10 9:59 ` Jisheng Zhang
0 siblings, 1 reply; 4+ messages in thread
From: Jisheng Zhang @ 2016-08-10 9:09 UTC (permalink / raw)
To: linux-arm-kernel
vdso_data_mapping is never modified, so mark it as const.
vdso_data_page and vdso_text_mapping are initialized by vdso_init(),
thereafter are mostly read during vdso special mapping handling.
The fact that they are mostly read and not written to makes them
candidates for __read_mostly declarations.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
arch/arm/kernel/vdso.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index 994e971..c946092 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -47,13 +47,13 @@ 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 __read_mostly;
+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 __read_mostly = {
.name = "[vdso]",
};
--
2.8.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] ARM: VDSO: put read only/mostly objects into proper sections
2016-08-10 9:09 [PATCH] ARM: VDSO: put read only/mostly objects into proper sections Jisheng Zhang
@ 2016-08-10 9:59 ` Jisheng Zhang
2016-08-10 18:47 ` Kees Cook
0 siblings, 1 reply; 4+ messages in thread
From: Jisheng Zhang @ 2016-08-10 9:59 UTC (permalink / raw)
To: linux-arm-kernel
+ Kees
On Wed, 10 Aug 2016 17:09:47 +0800 wrote:
> vdso_data_mapping is never modified, so mark it as const.
>
> vdso_data_page and vdso_text_mapping are initialized by vdso_init(),
> thereafter are mostly read during vdso special mapping handling.
>
> The fact that they are mostly read and not written to makes them
> candidates for __read_mostly declarations.
Inspired by Kees's "arm: apply more __ro_after_init", is it better
to mark these vars as __ro_after_init?
Thanks,
Jisheng
>
> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---
> arch/arm/kernel/vdso.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
> index 994e971..c946092 100644
> --- a/arch/arm/kernel/vdso.c
> +++ b/arch/arm/kernel/vdso.c
> @@ -47,13 +47,13 @@ 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 __read_mostly;
> +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 __read_mostly = {
> .name = "[vdso]",
> };
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] ARM: VDSO: put read only/mostly objects into proper sections
2016-08-10 9:59 ` Jisheng Zhang
@ 2016-08-10 18:47 ` Kees Cook
2016-08-10 19:04 ` Nathan Lynch
0 siblings, 1 reply; 4+ messages in thread
From: Kees Cook @ 2016-08-10 18:47 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Aug 10, 2016 at 2:59 AM, Jisheng Zhang <jszhang@marvell.com> wrote:
> + Kees
>
> On Wed, 10 Aug 2016 17:09:47 +0800 wrote:
>
>> vdso_data_mapping is never modified, so mark it as const.
>>
>> vdso_data_page and vdso_text_mapping are initialized by vdso_init(),
>> thereafter are mostly read during vdso special mapping handling.
>>
>> The fact that they are mostly read and not written to makes them
>> candidates for __read_mostly declarations.
>
> Inspired by Kees's "arm: apply more __ro_after_init", is it better
> to mark these vars as __ro_after_init?
Yeah, if they're not written outside of __init, please do. It would be
a nice complement to commit 11bf9b865898 ("ARM/vdso: Mark the vDSO
code read-only after init").
-Kees
>
> Thanks,
> Jisheng
>
>>
>> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
>> ---
>> arch/arm/kernel/vdso.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
>> index 994e971..c946092 100644
>> --- a/arch/arm/kernel/vdso.c
>> +++ b/arch/arm/kernel/vdso.c
>> @@ -47,13 +47,13 @@ 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 __read_mostly;
>> +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 __read_mostly = {
>> .name = "[vdso]",
>> };
>>
>
--
Kees Cook
Nexus Security
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] ARM: VDSO: put read only/mostly objects into proper sections
2016-08-10 18:47 ` Kees Cook
@ 2016-08-10 19:04 ` Nathan Lynch
0 siblings, 0 replies; 4+ messages in thread
From: Nathan Lynch @ 2016-08-10 19:04 UTC (permalink / raw)
To: linux-arm-kernel
On 08/10/2016 01:47 PM, Kees Cook wrote:
> On Wed, Aug 10, 2016 at 2:59 AM, Jisheng Zhang <jszhang@marvell.com> wrote:
>> + Kees
>>
>> On Wed, 10 Aug 2016 17:09:47 +0800 wrote:
>>
>>> vdso_data_mapping is never modified, so mark it as const.
>>>
>>> vdso_data_page and vdso_text_mapping are initialized by vdso_init(),
>>> thereafter are mostly read during vdso special mapping handling.
>>>
>>> The fact that they are mostly read and not written to makes them
>>> candidates for __read_mostly declarations.
>>
>> Inspired by Kees's "arm: apply more __ro_after_init", is it better
>> to mark these vars as __ro_after_init?
>
> Yeah, if they're not written outside of __init, please do. It would be
> a nice complement to commit 11bf9b865898 ("ARM/vdso: Mark the vDSO
> code read-only after init").
I agree.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-08-10 9:59 ` Jisheng Zhang
2016-08-10 18:47 ` Kees Cook
2016-08-10 19:04 ` Nathan Lynch
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