[PATCH v4 3/5] arm64: mm: support batch clearing of the young flag for large folios

[Baolin Wang]

Currently, contpte_ptep_test_and_clear_young() and contpte_ptep_clear_flush_young()
only clear the young flag and flush TLBs for PTEs within the contiguous range.
To support batch PTE operations for other sized large folios in the following
patches, adding a new parameter to specify the number of PTEs that map consecutive
pages of the same large folio in a single VMA and a single page table.

While we are at it, rename the functions to maintain consistency with other
contpte_*() functions.

Signed-off-by: Baolin Wang <baolin.wang at linux.alibaba.com>
---
 arch/arm64/include/asm/pgtable.h | 12 ++++++------
 arch/arm64/mm/contpte.c          | 33 ++++++++++++++++++--------------
 2 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 445e18e92221..d5fbe72e820a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1648,10 +1648,10 @@ extern void contpte_clear_full_ptes(struct mm_struct *mm, unsigned long addr,
 extern pte_t contpte_get_and_clear_full_ptes(struct mm_struct *mm,
 				unsigned long addr, pte_t *ptep,
 				unsigned int nr, int full);
-extern int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma,
-				unsigned long addr, pte_t *ptep);
-extern int contpte_ptep_clear_flush_young(struct vm_area_struct *vma,
-				unsigned long addr, pte_t *ptep);
+int contpte_test_and_clear_young_ptes(struct vm_area_struct *vma,
+				unsigned long addr, pte_t *ptep, unsigned int nr);
+int contpte_clear_flush_young_ptes(struct vm_area_struct *vma,
+				unsigned long addr, pte_t *ptep, unsigned int nr);
 extern void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
 				pte_t *ptep, unsigned int nr);
 extern int contpte_ptep_set_access_flags(struct vm_area_struct *vma,
@@ -1823,7 +1823,7 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
 	if (likely(!pte_valid_cont(orig_pte)))
 		return __ptep_test_and_clear_young(vma, addr, ptep);
 
-	return contpte_ptep_test_and_clear_young(vma, addr, ptep);
+	return contpte_test_and_clear_young_ptes(vma, addr, ptep, CONT_PTES);
 }
 
 #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
@@ -1835,7 +1835,7 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 	if (likely(!pte_valid_cont(orig_pte)))
 		return __ptep_clear_flush_young(vma, addr, ptep);
 
-	return contpte_ptep_clear_flush_young(vma, addr, ptep);
+	return contpte_clear_flush_young_ptes(vma, addr, ptep, CONT_PTES);
 }
 
 #define wrprotect_ptes wrprotect_ptes
diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
index e4ddeb46f25d..b929a455103f 100644
--- a/arch/arm64/mm/contpte.c
+++ b/arch/arm64/mm/contpte.c
@@ -508,8 +508,9 @@ pte_t contpte_get_and_clear_full_ptes(struct mm_struct *mm,
 }
 EXPORT_SYMBOL_GPL(contpte_get_and_clear_full_ptes);
 
-int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma,
-					unsigned long addr, pte_t *ptep)
+int contpte_test_and_clear_young_ptes(struct vm_area_struct *vma,
+					unsigned long addr, pte_t *ptep,
+					unsigned int nr)
 {
 	/*
 	 * ptep_clear_flush_young() technically requires us to clear the access
@@ -518,41 +519,45 @@ int contpte_ptep_test_and_clear_young(struct vm_area_struct *vma,
 	 * contig range when the range is covered by a single folio, we can get
 	 * away with clearing young for the whole contig range here, so we avoid
 	 * having to unfold.
+	 *
+	 * The 'nr' means consecutive (present) PTEs that map consecutive pages
+	 * of the same large folio in a single VMA and a single page table.
 	 */
 
+	unsigned long end = addr + nr * PAGE_SIZE;
 	int young = 0;
-	int i;
 
-	ptep = contpte_align_down(ptep);
-	addr = ALIGN_DOWN(addr, CONT_PTE_SIZE);
-
-	for (i = 0; i < CONT_PTES; i++, ptep++, addr += PAGE_SIZE)
+	ptep = contpte_align_addr_ptep(&addr, &end, ptep, nr);
+	for (; addr != end; ptep++, addr += PAGE_SIZE)
 		young |= __ptep_test_and_clear_young(vma, addr, ptep);
 
 	return young;
 }
-EXPORT_SYMBOL_GPL(contpte_ptep_test_and_clear_young);
+EXPORT_SYMBOL_GPL(contpte_test_and_clear_young_ptes);
 
-int contpte_ptep_clear_flush_young(struct vm_area_struct *vma,
-					unsigned long addr, pte_t *ptep)
+int contpte_clear_flush_young_ptes(struct vm_area_struct *vma,
+				unsigned long addr, pte_t *ptep,
+				unsigned int nr)
 {
 	int young;
 
-	young = contpte_ptep_test_and_clear_young(vma, addr, ptep);
+	young = contpte_test_and_clear_young_ptes(vma, addr, ptep, nr);
 
 	if (young) {
+		unsigned long end = addr + nr * PAGE_SIZE;
+
+		contpte_align_addr_ptep(&addr, &end, ptep, nr);
 		/*
 		 * See comment in __ptep_clear_flush_young(); same rationale for
 		 * eliding the trailing DSB applies here.
 		 */
-		addr = ALIGN_DOWN(addr, CONT_PTE_SIZE);
-		__flush_tlb_range_nosync(vma->vm_mm, addr, addr + CONT_PTE_SIZE,
+		__flush_tlb_range_nosync(vma->vm_mm, addr, end,
 					 PAGE_SIZE, true, 3);
 	}
 
 	return young;
 }
-EXPORT_SYMBOL_GPL(contpte_ptep_clear_flush_young);
+EXPORT_SYMBOL_GPL(contpte_clear_flush_young_ptes);
 
 void contpte_wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
 					pte_t *ptep, unsigned int nr)
-- 
2.47.3