From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
commit ab3f285f227fec62868037e9b1b1fd18294a83b8 upstream.
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>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
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 de8cbc30dcd1..5664be4a3680 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -788,11 +788,21 @@ 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;
+ }
new = old = pgste_get_lock(ptep);
pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
--
2.1.1
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