On 8/12/20 12:10 PM, Christophe Leroy wrote:
Le 12/08/2020 à 08:33, Aneesh Kumar K.V a écrit :
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 <aneesh.kumar@xxxxxxxxxxxxx>
---
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)
Do you mean:
#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, PPC_MASK_BITS |
S390_MASK_BITS)
IIUC GENMASK(hi, low) generate a mask from hi to low bits. Since i want
to avoid bit 62, I am forcing it to generate bits from (61, 4)
-aneesh
