[PATCH v1 02/14] arm64/mm: set_ptes()/set_pte_at(): New layer to manage contig bit

[Ryan Roberts <ryan.roberts@arm.com>]

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.

set_pte_at() is a core macro that forwards to set_ptes() (with nr=1).
Instead of creating a __set_pte_at() internal macro, convert all arch
users to use set_ptes()/__set_ptes() directly, as appropriate. Callers
in hugetlb may benefit from calling __set_ptes() once for their whole
range rather than managing their own loop. This is left for future
improvement.

No behavioural changes intended.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 arch/arm64/include/asm/pgtable.h | 12 +++++++++---
 arch/arm64/kernel/mte.c          |  2 +-
 arch/arm64/kvm/guest.c           |  2 +-
 arch/arm64/mm/fault.c            |  2 +-
 arch/arm64/mm/hugetlbpage.c      | 10 +++++-----
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7f5ce5687466..84919a3c558e 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -356,7 +356,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 	__set_pte(ptep, pte);
 }
 
-static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
+static inline void __set_ptes(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep, pte_t pte, unsigned int nr)
 {
 	page_table_check_ptes_set(mm, addr, ptep, pte, nr);
@@ -370,7 +370,6 @@ static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
 		pte_val(pte) += PAGE_SIZE;
 	}
 }
-#define set_ptes set_ptes
 
 /*
  * Huge pte definitions.
@@ -1067,7 +1066,7 @@ static inline void arch_swap_restore(swp_entry_t entry, struct folio *folio)
 #endif /* CONFIG_ARM64_MTE */
 
 /*
- * On AArch64, the cache coherency is handled via the set_pte_at() function.
+ * On AArch64, the cache coherency is handled via the __set_ptes() function.
  */
 static inline void update_mmu_cache_range(struct vm_area_struct *vma,
 		unsigned long addr, pte_t *ptep, unsigned int nr)
@@ -1134,6 +1133,13 @@ static inline void set_pte(pte_t *ptep, pte_t pte)
 	__set_pte(ptep, pte);
 }
 
+#define set_ptes set_ptes
+static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
+				pte_t *ptep, pte_t pte, unsigned int nr)
+{
+	__set_ptes(mm, addr, ptep, pte, nr);
+}
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_PGTABLE_H */
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 7e89968bd282..9b248549a020 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -90,7 +90,7 @@ int memcmp_pages(struct page *page1, struct page *page2)
 	/*
 	 * If the page content is identical but at least one of the pages is
 	 * tagged, return non-zero to avoid KSM merging. If only one of the
-	 * pages is tagged, set_pte_at() may zero or change the tags of the
+	 * pages is tagged, __set_ptes() may zero or change the tags of the
 	 * other page via mte_sync_tags().
 	 */
 	if (page_mte_tagged(page1) || page_mte_tagged(page2))
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 20280a5233f6..478df2edcf99 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -1087,7 +1087,7 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
 		} else {
 			/*
 			 * Only locking to serialise with a concurrent
-			 * set_pte_at() in the VMM but still overriding the
+			 * __set_ptes() in the VMM but still overriding the
 			 * tags, hence ignoring the return value.
 			 */
 			try_page_mte_tagging(page);
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 6045a5117ac1..d3a64624ed88 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -191,7 +191,7 @@ 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_pte_at(), 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.
  */
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 95364e8bdc19..31a1da655bf1 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -264,12 +264,12 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 		ncontig = num_contig_ptes(folio_size(folio), &pgsize);
 
 		for (i = 0; i < ncontig; i++, ptep++)
-			set_pte_at(mm, addr, ptep, pte);
+			__set_ptes(mm, addr, ptep, pte, 1);
 		return;
 	}
 
 	if (!pte_cont(pte)) {
-		set_pte_at(mm, addr, ptep, pte);
+		__set_ptes(mm, addr, ptep, pte, 1);
 		return;
 	}
 
@@ -281,7 +281,7 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 	clear_flush(mm, addr, ptep, pgsize, ncontig);
 
 	for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
-		set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
+		__set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
 }
 
 pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -496,7 +496,7 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 
 	hugeprot = pte_pgprot(pte);
 	for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
-		set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
+		__set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
 
 	return 1;
 }
@@ -525,7 +525,7 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
 	pfn = pte_pfn(pte);
 
 	for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
-		set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
+		__set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
 }
 
 pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
-- 
2.25.1