arm64/mm: new ptep layer to manage contig bit

Create a new layer for the in-table PTE manipulation APIs.  For now, The
existing API is prefixed with double underscore to become the arch-private
API and the public API is just a simple wrapper that calls the private
API.

The public API implementation will subsequently be used to transparently
manipulate the contiguous bit where appropriate.  But since there are
already some contig-aware users (e.g.  hugetlb, kernel mapper), we must
first ensure those users use the private API directly so that the future
contig-bit manipulations in the public API do not interfere with those
existing uses.

The following APIs are treated this way:

 - ptep_get
 - set_pte
 - set_ptes
 - pte_clear
 - ptep_get_and_clear
 - ptep_test_and_clear_young
 - ptep_clear_flush_young
 - ptep_set_wrprotect
 - ptep_set_access_flags

Link: https://lkml.kernel.org/r/20240215103205.2607016-11-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Tested-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 3235e23309ec..9a1c66183d16 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -191,7 +191,7 @@ static void show_pte(unsigned long addr)
 		if (!ptep)
 			break;
 
-		pte = ptep_get(ptep);
+		pte = __ptep_get(ptep);
 		pr_cont(", pte=%016llx", pte_val(pte));
 		pte_unmap(ptep);
 	} while(0);
@@ -205,16 +205,16 @@ static void show_pte(unsigned long addr)
  *
  * It needs to cope with hardware update of the accessed/dirty state by other
  * agents in the system and can safely skip the __sync_icache_dcache() call as,
- * like set_ptes(), the PTE is never changed from no-exec to exec here.
+ * like __set_ptes(), the PTE is never changed from no-exec to exec here.
  *
  * Returns whether or not the PTE actually changed.
  */
-int ptep_set_access_flags(struct vm_area_struct *vma,
-			  unsigned long address, pte_t *ptep,
-			  pte_t entry, int dirty)
+int __ptep_set_access_flags(struct vm_area_struct *vma,
+			    unsigned long address, pte_t *ptep,
+			    pte_t entry, int dirty)
 {
 	pteval_t old_pteval, pteval;
-	pte_t pte = ptep_get(ptep);
+	pte_t pte = __ptep_get(ptep);
 
 	if (pte_same(pte, entry))
 		return 0;