linux-kernel - [PATCH] riscv: Implement pte

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Message-Id: <20240128115953.25085-1-alexghiti@rivosinc.com>
Date: Sun, 28 Jan 2024 12:59:53 +0100
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Alexandre Ghiti <alexghiti@...osinc.com>
Subject: [PATCH] riscv: Implement pte_accessible()

Like other architectures, a pte is accessible if it is present or if
there is a pending tlb flush and the pte is protnone (which could be the
case when a pte is downgraded to protnone before a flush tlb is
executed).

Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/include/asm/pgtable.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 0c94260b5d0c..3b46677827f6 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -353,6 +353,19 @@ static inline int pte_present(pte_t pte)
 	return (pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROT_NONE));
 }
 
+#define pte_accessible pte_accessible
+static inline unsigned long pte_accessible(struct mm_struct *mm, pte_t a)
+{
+	if (pte_val(a) & _PAGE_PRESENT)
+		return true;
+
+	if ((pte_val(a) & _PAGE_PROT_NONE) &&
+	    atomic_read(&mm->tlb_flush_pending))
+		return true;
+
+	return false;
+}
+
 static inline int pte_none(pte_t pte)
 {
 	return (pte_val(pte) == 0);
-- 
2.39.2