Add protection key to calc_vm_prot_bits() if building under kernel >= 4.5.0

kernel/ashmem/ashmem.c

@@ -33,6 +33,7 @@
 #include <linux/bitops.h>
 #include <linux/mutex.h>
 #include <linux/shmem_fs.h>
+#include <linux/version.h>
 #include "ashmem.h"
 
 #define ASHMEM_NAME_PREFIX "dev/ashmem/"
@@ -373,8 +374,13 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
 	}
 
 	/* requested protection bits must match our allowed protection mask */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0)
+	if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
+		     calc_vm_prot_bits(PROT_MASK, 0))) {
+#else
 	if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) &
 		     calc_vm_prot_bits(PROT_MASK))) {
+#endif
 		ret = -EPERM;
 		goto out;
 	}