feat: implement SV39 page table interface and operations for RISC-V architecture

1 files changed, 42 insertions, 0 deletions

diff --git a/na/arch/riscv/include/arch/pmap.h b/na/arch/riscv/include/arch/pmap.h
new file mode 100644
index 0000000..3f0b142
--- /dev/null
+++ b/na/arch/riscv/include/arch/pmap.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+#pragma once
+
+/*
+ * pmap — SV39 page table interface (MD layer)
+ *
+ * Namespace functions, zero runtime overhead.
+ * Implementation: arch/riscv/mm/pmap.cc
+ *
+ * Reference: docs/specs/vmm.md §3.2
+ */
+
+#include <lume/types.h>
+
+namespace pmap {
+
+/* PTE permission bits */
+inline constexpr uint64 PTE_V = 1ULL << 0;
+inline constexpr uint64 PTE_R = 1ULL << 1;
+inline constexpr uint64 PTE_W = 1ULL << 2;
+inline constexpr uint64 PTE_X = 1ULL << 3;
+inline constexpr uint64 PTE_U = 1ULL << 4;
+inline constexpr uint64 PTE_G = 1ULL << 5;
+inline constexpr uint64 PTE_A = 1ULL << 6;
+inline constexpr uint64 PTE_D = 1ULL << 7;
+
+uint64 create();
+void destroy(uint64 root_pa);
+int map(uint64 root_pa, uint64 va, uint64 pa, uint64 perm);
+void unmap(uint64 root_pa, uint64 va);
+bool lookup(uint64 root_pa, uint64 va, uint64* pa_out);
+void activate(uint64 root_pa);
+
+/*
+ * Translate MI-layer VM_* permission flags to hardware PTE bits.
+ * Called by vma.cc when faulting in a page.
+ */
+uint64 vm_perm_to_pte(uint64 vm_perm);
+
+} // namespace pmap