mm/x86: implement arch_check_zapped_pud()

Introduce arch_check_zapped_pud() to sanity check shadow stack on PUD
zaps.  It has the same logic as the PMD helper.

One thing to mention is, it might be a good idea to use page_table_check
in the future for trapping wrong setups of shadow stack pgtable entries
[1].  That is left for the future as a separate effort.

[1] https://lore.kernel.org/all/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: "Edgecombe, Rick P" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index f5931499c2d6..36e7139a61d9 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -926,3 +926,9 @@ void arch_check_zapped_pmd(struct vm_area_struct *vma, pmd_t pmd)
 	VM_WARN_ON_ONCE(!(vma->vm_flags & VM_SHADOW_STACK) &&
 			pmd_shstk(pmd));
 }
+
+void arch_check_zapped_pud(struct vm_area_struct *vma, pud_t pud)
+{
+	/* See note in arch_check_zapped_pte() */
+	VM_WARN_ON_ONCE(!(vma->vm_flags & VM_SHADOW_STACK) && pud_shstk(pud));
+}