Subject: [PATCH 02/16] debug_vm_pgtable/ppc64: Avoid setting top bits in radom value

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Wed, 12 Aug 2020 12:03:44 +0530

ppc64 use bit 62 to indicate a pte entry (_PAGE_PTE). Avoid setting that bit in
random value.

Signed-off-by: Aneesh Kumar K.V <[email-masked]>
---
 mm/debug_vm_pgtable.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 086309fb9b6f..4c32063a8acf 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -45,9 +45,12 @@
  * pxx_clear() because of how dynamic page table folding works on s390. So
  * while loading up the entries do not change the lower 4 bits. It does not
  * have affect any other platform.
+ *
+ * Also avoid the 62nd bit on ppc64 that is used to mark a pte entry.
  */
 #define S390_MASK_BITS	4
-#define RANDOM_ORVALUE	GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS)
+#define PPC_MASK_BITS	2
+#define RANDOM_ORVALUE	GENMASK(BITS_PER_LONG - 1 - PPC_MASK_BITS, S390_MASK_BITS)
 #define RANDOM_NZVALUE	GENMASK(7, 0)
 
 static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
-- 
2.26.2