mm: ptep_clear() page table helper

We have ptep_get_and_clear() and ptep_get_and_clear_full() helpers to
clear PTE from user page tables, but there is no variant for simple
clear of a present PTE from user page tables without using a low level
pte_clear() which can be either native or para-virtualised.

Add a new ptep_clear() that can be used in common code to clear PTEs
from page table.  We will need this call later in order to add a hook
for page table check.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Pasha Tatashin <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sami Tolvanen <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Wei Xu <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 2a2b24e87877..a7ac97c76762 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -652,7 +652,7 @@ static void __init pte_clear_tests(struct pgtable_debug_args *args)
 	set_pte_at(args->mm, args->vaddr, args->ptep, pte);
 	flush_dcache_page(page);
 	barrier();
-	pte_clear(args->mm, args->vaddr, args->ptep);
+	ptep_clear(args->mm, args->vaddr, args->ptep);
 	pte = ptep_get(args->ptep);
 	WARN_ON(!pte_none(pte));
 }