[PATCH v8 01/10] ARM: use _install_special_mapping for sigpage

[Nathan_Lynch@mentor.com (Nathan Lynch)]

On 08/04/2014 07:46 AM, Will Deacon wrote:
> On Sat, Aug 02, 2014 at 07:16:38PM +0100, Nathan Lynch wrote:
>> _install_special_mapping allows the VMA to be identifed in
>> /proc/pid/maps without the use of arch_vma_name, providing a
>> slight net reduction in object size:
>>
>>   text    data     bss     dec     hex filename
>>   2996      96     144    3236     ca4 arch/arm/kernel/process.o (before)
>>   2956     104     144    3204     c84 arch/arm/kernel/process.o (after)
>>
>> Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
>> Reviewed-by: Kees Cook <keescook@chromium.org>
>> ---
>>  arch/arm/kernel/process.c | 24 ++++++++++++++++--------
>>  1 file changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
>> index 81ef686a91ca..46fbbb3701a0 100644
>> --- a/arch/arm/kernel/process.c
>> +++ b/arch/arm/kernel/process.c
>> @@ -472,19 +472,23 @@ int in_gate_area_no_mm(unsigned long addr)
>>  
>>  const char *arch_vma_name(struct vm_area_struct *vma)
>>  {
>> -	return is_gate_vma(vma) ? "[vectors]" :
>> -		(vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage) ?
>> -		 "[sigpage]" : NULL;
>> +	return is_gate_vma(vma) ? "[vectors]" : NULL;
>>  }
> 
> Why do you need this function? I just removed it for arm64 and I think x86
> has done the same.

I think arch_vma_name is still needed for arm as long as the vectors
page is not installed using _install_special_mapping.  I'm honestly not
sure whether moving the vectors page to that API would be appropriate,
but it would be a larger undertaking.