[PATCH 2/3] Detect instruction fetch denied and report

[Balbir Singh]

On 09/11/16 03:09, Aneesh Kumar K.V wrote:
> Balbir Singh <bsingharora at gmail.com> writes:
> 
>> ISA 3 allows for prevention of instruction fetch and execution
>> of user mode pages. If such an error occurs, SRR1 bit 35
>> reports the error. We catch and report the error in do_page_fault()
>>
>> Signed-off-by: Balbir Singh <bsingharora at gmail.com>
>> ---
>>  arch/powerpc/mm/fault.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
>> index d0b137d..835fd03 100644
>> --- a/arch/powerpc/mm/fault.c
>> +++ b/arch/powerpc/mm/fault.c
>> @@ -404,6 +404,10 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
>>  		    (cpu_has_feature(CPU_FTR_NOEXECUTE) ||
>>  		     !(vma->vm_flags & (VM_READ | VM_WRITE))))
>>  			goto bad_area;
>> +
>> +		if (radix_enabled() && (regs->msr & SRR1_ISI_N_OR_G))
>> +			goto bad_area;
> 
> Why is this within radix_enabled() ? Hash can also generate an
> interrupt with that SRR1 value right ?
> 

Yes the bits are not specific to radix. I suspect the check above took
care of instruction exceptions, so we've never needed it before. I'll
remove the check

Balbir