diff mbox

[2/3] x86:add missing CONFIG_STRICT_KERNEL_RWX for mark_rodata_ro

Message ID 20180529133622.26982-1-nixiaoming@huawei.com (mailing list archive)
State New, archived
Headers show

Commit Message

Xiaoming Ni May 29, 2018, 1:36 p.m. UTC
mark_rodata_ro is only called by the function mark_readonly
when CONFIG_STRICT_KERNEL_RWX=y

if CONFIG_STRICT_KERNEL_RWX is not set
a compile warning may be triggered: unused function

Signed-off-by: nixiaoming <nixiaoming@huawei.com>
---
 arch/x86/mm/init_32.c | 2 ++
 arch/x86/mm/init_64.c | 2 ++
 2 files changed, 4 insertions(+)

Comments

Ingo Molnar May 30, 2018, 5:58 a.m. UTC | #1
* nixiaoming <nixiaoming@huawei.com> wrote:

> mark_rodata_ro is only called by the function mark_readonly
> when CONFIG_STRICT_KERNEL_RWX=y
> 
> if CONFIG_STRICT_KERNEL_RWX is not set
> a compile warning may be triggered: unused function
> 
> Signed-off-by: nixiaoming <nixiaoming@huawei.com>
> ---
>  arch/x86/mm/init_32.c | 2 ++
>  arch/x86/mm/init_64.c | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
> index c893c6a..121c567 100644
> --- a/arch/x86/mm/init_32.c
> +++ b/arch/x86/mm/init_32.c
> @@ -920,6 +920,7 @@ static void mark_nxdata_nx(void)
>  	set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
>  }
>  
> +#ifdef CONFIG_STRICT_KERNEL_RWX
>  void mark_rodata_ro(void)
>  {
>  	unsigned long start = PFN_ALIGN(_text);
> @@ -957,3 +958,4 @@ void mark_rodata_ro(void)
>  	if (__supported_pte_mask & _PAGE_NX)
>  		debug_checkwx();
>  }
> +#endif /*end of CONFIG_STRICT_KERNEL_RWX*/
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 0a40060..1b7a1a7 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1245,6 +1245,7 @@ void set_kernel_text_ro(void)
>  	set_memory_ro(start, (end - start) >> PAGE_SHIFT);
>  }
>  
> +#ifdef CONFIG_STRICT_KERNEL_RWX
>  void mark_rodata_ro(void)
>  {
>  	unsigned long start = PFN_ALIGN(_text);
> @@ -1298,6 +1299,7 @@ void mark_rodata_ro(void)
>  	 */
>  	pti_clone_kernel_text();
>  }
> +#endif

NAK, this is very ugly and the changelog doesn't appear to be true: the build 
warning does not trigger in the default build, correct?

Thanks,

	Ingo
Ard Biesheuvel May 30, 2018, 6:07 a.m. UTC | #2
On 30 May 2018 at 07:58, Ingo Molnar <mingo@kernel.org> wrote:
>
> * nixiaoming <nixiaoming@huawei.com> wrote:
>
>> mark_rodata_ro is only called by the function mark_readonly
>> when CONFIG_STRICT_KERNEL_RWX=y
>>
>> if CONFIG_STRICT_KERNEL_RWX is not set
>> a compile warning may be triggered: unused function
>>
>> Signed-off-by: nixiaoming <nixiaoming@huawei.com>
>> ---
>>  arch/x86/mm/init_32.c | 2 ++
>>  arch/x86/mm/init_64.c | 2 ++
>>  2 files changed, 4 insertions(+)
>>
>> diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
>> index c893c6a..121c567 100644
>> --- a/arch/x86/mm/init_32.c
>> +++ b/arch/x86/mm/init_32.c
>> @@ -920,6 +920,7 @@ static void mark_nxdata_nx(void)
>>       set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
>>  }
>>
>> +#ifdef CONFIG_STRICT_KERNEL_RWX
>>  void mark_rodata_ro(void)
>>  {
>>       unsigned long start = PFN_ALIGN(_text);
>> @@ -957,3 +958,4 @@ void mark_rodata_ro(void)
>>       if (__supported_pte_mask & _PAGE_NX)
>>               debug_checkwx();
>>  }
>> +#endif /*end of CONFIG_STRICT_KERNEL_RWX*/
>> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
>> index 0a40060..1b7a1a7 100644
>> --- a/arch/x86/mm/init_64.c
>> +++ b/arch/x86/mm/init_64.c
>> @@ -1245,6 +1245,7 @@ void set_kernel_text_ro(void)
>>       set_memory_ro(start, (end - start) >> PAGE_SHIFT);
>>  }
>>
>> +#ifdef CONFIG_STRICT_KERNEL_RWX
>>  void mark_rodata_ro(void)
>>  {
>>       unsigned long start = PFN_ALIGN(_text);
>> @@ -1298,6 +1299,7 @@ void mark_rodata_ro(void)
>>        */
>>       pti_clone_kernel_text();
>>  }
>> +#endif
>
> NAK, this is very ugly and the changelog doesn't appear to be true: the build
> warning does not trigger in the default build, correct?
>

I don't see how the build warning could trigger at all, given that
mark_rodata_ro() has external linkage.
Xiaoming Ni May 30, 2018, 6:51 a.m. UTC | #3
On 30 May 2018 at 2:07PM Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org] wrote:

>On 30 May 2018 at 07:58, Ingo Molnar <mingo@kernel.org> wrote:
>>
>> * nixiaoming <nixiaoming@huawei.com> wrote:
>>
>>> mark_rodata_ro is only called by the function mark_readonly
>>> when CONFIG_STRICT_KERNEL_RWX=y
>>>
>>> if CONFIG_STRICT_KERNEL_RWX is not set
>>> a compile warning may be triggered: unused function
>....
>>
>> NAK, this is very ugly and the changelog doesn't appear to be true: the build
>> warning does not trigger in the default build, correct?
>>
>
>I don't see how the build warning could trigger at all, given that
>mark_rodata_ro() has external linkage.
>

Unable to set CONFIG_STRICT_KERNEL_RWX=n by make menuconfig ARCH=x86_64
the build warning does not trigger in the default build, 
but it should be more appropriate to add CONFIG control to the code.
diff mbox

Patch

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index c893c6a..121c567 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -920,6 +920,7 @@  static void mark_nxdata_nx(void)
 	set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
 }
 
+#ifdef CONFIG_STRICT_KERNEL_RWX
 void mark_rodata_ro(void)
 {
 	unsigned long start = PFN_ALIGN(_text);
@@ -957,3 +958,4 @@  void mark_rodata_ro(void)
 	if (__supported_pte_mask & _PAGE_NX)
 		debug_checkwx();
 }
+#endif /*end of CONFIG_STRICT_KERNEL_RWX*/
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 0a40060..1b7a1a7 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1245,6 +1245,7 @@  void set_kernel_text_ro(void)
 	set_memory_ro(start, (end - start) >> PAGE_SHIFT);
 }
 
+#ifdef CONFIG_STRICT_KERNEL_RWX
 void mark_rodata_ro(void)
 {
 	unsigned long start = PFN_ALIGN(_text);
@@ -1298,6 +1299,7 @@  void mark_rodata_ro(void)
 	 */
 	pti_clone_kernel_text();
 }
+#endif
 
 int kern_addr_valid(unsigned long addr)
 {