On Thu, 01 Dec 2022 05:51:28 PST (-0800), alexghiti@xxxxxxxxxxxx wrote:
RISC-V kernels support 3,4,5-level page tables at runtime by folding
upper levels.
In case of a 3-level page table, PGDIR is folded into P4D which in turn
is folded into PUD: PGDIR_SHIFT value is correctly set to the same value
as PUD_SHIFT, but P4D_SHIFT is not, then any use of P4D_SHIFT will access
invalid address bits (all set to 1).
Fix this by dynamically defining P4D_SHIFT value, like we already do for
PGDIR_SHIFT.
Fixes: d10efa21a937 ("riscv: mm: Control p4d's folding by pgtable_l5_enabled")
Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
---
arch/riscv/include/asm/pgtable-64.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index dc42375c2357..42a042c0e13e 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -25,7 +25,11 @@ extern bool pgtable_l5_enabled;
#define PGDIR_MASK (~(PGDIR_SIZE - 1))
/* p4d is folded into pgd in case of 4-level page table */
-#define P4D_SHIFT 39
+#define P4D_SHIFT_L3 30
+#define P4D_SHIFT_L4 39
+#define P4D_SHIFT_L5 39
+#define P4D_SHIFT (pgtable_l5_enabled ? P4D_SHIFT_L5 : \
+ (pgtable_l4_enabled ? P4D_SHIFT_L4 : P4D_SHIFT_L3))
#define P4D_SIZE (_AC(1, UL) << P4D_SHIFT)
#define P4D_MASK (~(P4D_SIZE - 1))
Reviewed-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Too late for this week, but if someone's got a concrete regression then
I'm happy to take it next week. Otherwise it'll end up on for-next,
it'll be backported anyway but this way it'll have a touch more time.
Thanks!
