On 27/08/14 05:06, Ben Hutchings wrote:
> On Mon, 2014-08-25 at 15:10 +0200, Christian Borntraeger wrote:
>> The PFMF instruction handler blindly wrote the storage key even if
>> the page was mapped R/O in the host. Lets try a COW before continuing
>> and bail out in case of errors.
>>
>> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>> Reviewed-by: Dominik Dingel <dingel@xxxxxxxxxxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
>> ---
>> arch/s390/mm/pgtable.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
>> index 19daa53..5404a62 100644
>> --- a/arch/s390/mm/pgtable.c
>> +++ b/arch/s390/mm/pgtable.c
>> @@ -986,11 +986,21 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
>> pte_t *ptep;
>>
>> down_read(&mm->mmap_sem);
>> +retry:
>> ptep = get_locked_pte(current->mm, addr, &ptl);
>> if (unlikely(!ptep)) {
>> up_read(&mm->mmap_sem);
>> return -EFAULT;
>> }
>> + if (!(pte_val(*ptep) & _PAGE_INVALID) &&
>> + (pte_val(*ptep) & _PAGE_PROTECT)) {
>> + pte_unmap_unlock(*ptep, ptl);
>> + if (fixup_user_fault(current, mm, addr, FAULT_FLAG_WRITE)) {
>> + up_read(&mm->mmap_sem);
>> + return -EFAULT;
>> + }
>> + goto retry;
>> + }
>
> Every line below the first 'if' is indented one tab stop too far.
>
> Ben.
>
>> new = old = pgste_get_lock(ptep);
>> pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
>
Hmm, indeed. Drat. Paolo, do you want a revert, resend?
Christian
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