linux-kernel - [PATCH v2 3/7] mm: Add batched versions of ptep_modify_prot

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Message-Id: <20250429052336.18912-4-dev.jain@arm.com>
Date: Tue, 29 Apr 2025 10:53:32 +0530
From: Dev Jain <dev.jain@....com>
To: akpm@...ux-foundation.org
Cc: ryan.roberts@....com,
	david@...hat.com,
	willy@...radead.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	catalin.marinas@....com,
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	Liam.Howlett@...cle.com,
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	Dev Jain <dev.jain@....com>
Subject: [PATCH v2 3/7] mm: Add batched versions of ptep_modify_prot_start/commit

Batch ptep_modify_prot_start/commit in preparation for optimizing mprotect.
Architecture can override these helpers.

Signed-off-by: Dev Jain <dev.jain@....com>
---
 include/linux/pgtable.h | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index b50447ef1c92..ed287289335f 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -891,6 +891,44 @@ static inline void wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
 }
 #endif
 
+/* See the comment for ptep_modify_prot_start */
+#ifndef modify_prot_start_ptes
+static inline pte_t modify_prot_start_ptes(struct vm_area_struct *vma,
+		unsigned long addr, pte_t *ptep, unsigned int nr)
+{
+	pte_t pte, tmp_pte;
+
+	pte = ptep_modify_prot_start(vma, addr, ptep);
+	while (--nr) {
+		ptep++;
+		addr += PAGE_SIZE;
+		tmp_pte = ptep_modify_prot_start(vma, addr, ptep);
+		if (pte_dirty(tmp_pte))
+			pte = pte_mkdirty(pte);
+		if (pte_young(tmp_pte))
+			pte = pte_mkyoung(pte);
+	}
+	return pte;
+}
+#endif
+
+/* See the comment for ptep_modify_prot_commit */
+#ifndef modify_prot_commit_ptes
+static inline void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr,
+		pte_t *ptep, pte_t old_pte, pte_t pte, unsigned int nr)
+{
+	for (;;) {
+		ptep_modify_prot_commit(vma, addr, ptep, old_pte, pte);
+		if (--nr == 0)
+			break;
+		ptep++;
+		addr += PAGE_SIZE;
+		old_pte = pte_next_pfn(old_pte);
+		pte = pte_next_pfn(pte);
+	}
+}
+#endif
+
 /*
  * On some architectures hardware does not set page access bit when accessing
  * memory page, it is responsibility of software setting this bit. It brings
-- 
2.30.2