To clone page table of PMD-mapped pages, pti_clone_pgtable() requires PMD
aligned start address. [1] adds warning for unaligned addresses. However,
there is still no warning for unaligned address to valid huge pmd [2].
Add alignment check in valid pmd_large() case. If the address is
unaligned, round it down to the nearest PMD aligned address and show
warning.
[1] commit 825d0b73cd75 ("x86/mm/pti: Handle unaligned address gracefully
in pti_clone_pagetable()")
[2]
https://lore.kernel.org/lkml/156864062019.3407.14798418565580024723.t...@nanos.tec.linutronix.de/
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Signed-off-by: Song Liu <[email protected]>
---
arch/x86/mm/pti.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 7f2140414440..d224115c350d 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -343,6 +343,10 @@ pti_clone_pgtable(unsigned long start, unsigned long end,
}
if (pmd_large(*pmd) || level == PTI_CLONE_PMD) {
+ /* warn and round_down() unaligned addr */
+ if (WARN_ON_ONCE(addr & ~PMD_MASK))
+ addr &= PMD_MASK;
+
target_pmd = pti_user_pagetable_walk_pmd(addr);
if (WARN_ON(!target_pmd))
return;
--
2.17.1
