arm64: Make !dirty ptes read-only

The AArch64 Linux port relies on the mm code to wrprotect clean ptes.
This however is not the case with newly created ptes and
PAGE_SHARED(_EXEC) is writable but !dirty.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 8960239be722..937ae2064682 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -159,6 +159,8 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 {
         if (pte_present_exec_user(pte))
                 __sync_icache_dcache(pte, addr);
+        if (!pte_dirty(pte))
+                pte = pte_wrprotect(pte);
         set_pte(ptep, pte);
 }