[PATCH 07/10] mm: Introduce ctor/dtor at P4D level

[Kevin Brodsky <kevin.brodsky@arm.com>]

Commit 55d2a0bd5ead ("mm: add statistics for PUD level pagetable")
added accounting for PUD-level page tables. This patch does exactly
the same thing for P4D-level page tables, introducing
pagetable_p4d_[cd]tor with the same implementation as the PUD
ctor/dtor and calling them on all alloc/free paths.

Besides the small improvement in accounting accuracy, this also
enables adding construction/destruction hooks in just one generic
place for page tables at P4D level (like lower levels).

Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
 arch/riscv/include/asm/pgalloc.h |  8 ++++++--
 arch/s390/include/asm/pgalloc.h  | 12 ++++++++----
 arch/x86/mm/pgtable.c            |  3 +++
 include/asm-generic/pgalloc.h    |  2 ++
 include/linux/mm.h               | 10 ++++++++++
 5 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
index 551d614d3369..3c364ecc3100 100644
--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -108,8 +108,12 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
 				  unsigned long addr)
 {
-	if (pgtable_l5_enabled)
-		riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(p4d));
+	if (pgtable_l5_enabled) {
+		struct ptdesc *ptdesc = virt_to_ptdesc(p4d);
+
+		pagetable_p4d_dtor(ptdesc);
+		riscv_tlb_remove_ptdesc(tlb, ptdesc);
+	}
 }
 #endif /* __PAGETABLE_PMD_FOLDED */
 
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 97db66ae06b9..85a5d07365aa 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -53,15 +53,19 @@ static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long address)
 {
 	unsigned long *table = crst_table_alloc(mm);
 
-	if (table)
-		crst_table_init(table, _REGION2_ENTRY_EMPTY);
+	if (!table)
+		return NULL;
+	crst_table_init(table, _REGION2_ENTRY_EMPTY);
+	pagetable_p4d_ctor(virt_to_ptdesc(table));
 	return (p4d_t *) table;
 }
 
 static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
 {
-	if (!mm_p4d_folded(mm))
-		crst_table_free(mm, (unsigned long *) p4d);
+	if (mm_p4d_folded(mm))
+		return;
+	pagetable_p4d_dtor(virt_to_ptdesc(p4d));
+	crst_table_free(mm, (unsigned long *) p4d);
 }
 
 static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 5745a354a241..c1bfdf7b4767 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -86,6 +86,9 @@ void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
 #if CONFIG_PGTABLE_LEVELS > 4
 void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
 {
+	struct ptdesc *ptdesc = virt_to_ptdesc(p4d);
+
+	pagetable_p4d_dtor(ptdesc);
 	paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
 	paravirt_tlb_remove_table(tlb, virt_to_page(p4d));
 }
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 59131629ac9c..bb482eeca0c3 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -230,6 +230,7 @@ static inline p4d_t *__p4d_alloc_one_noprof(struct mm_struct *mm, unsigned long
 	if (!ptdesc)
 		return NULL;
 
+	pagetable_p4d_ctor(ptdesc);
 	return ptdesc_address(ptdesc);
 }
 #define __p4d_alloc_one(...)	alloc_hooks(__p4d_alloc_one_noprof(__VA_ARGS__))
@@ -247,6 +248,7 @@ static inline void __p4d_free(struct mm_struct *mm, p4d_t *p4d)
 	struct ptdesc *ptdesc = virt_to_ptdesc(p4d);
 
 	BUG_ON((unsigned long)p4d & (PAGE_SIZE-1));
+	pagetable_p4d_dtor(ptdesc);
 	pagetable_free(ptdesc);
 }
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a5b482362792..e8b92f4bf3f1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3161,6 +3161,16 @@ static inline void pagetable_pud_dtor(struct ptdesc *ptdesc)
 	__pagetable_dtor(ptdesc);
 }
 
+static inline void pagetable_p4d_ctor(struct ptdesc *ptdesc)
+{
+	__pagetable_ctor(ptdesc);
+}
+
+static inline void pagetable_p4d_dtor(struct ptdesc *ptdesc)
+{
+	__pagetable_dtor(ptdesc);
+}
+
 extern void __init pagecache_init(void);
 extern void free_initmem(void);
 
-- 
2.47.0