From 8878e0c8157c733f446f5a4f6653bf71253805b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Holz?= <sholz8530@gmail.com>
Date: Sun, 28 Jan 2024 13:59:52 +0100
Subject: [PATCH] Kernel/riscv64: Implement everything in PageDirectory.cpp

This code is heavily based on aarch64's PageDirectory.cpp.
---
 Kernel/Arch/riscv64/PageDirectory.cpp | 72 ++++++++++++++++++++++-----
 1 file changed, 60 insertions(+), 12 deletions(-)

diff --git a/Kernel/Arch/riscv64/PageDirectory.cpp b/Kernel/Arch/riscv64/PageDirectory.cpp
index 4e7ab2b0c75..faa14a31ae7 100644
--- a/Kernel/Arch/riscv64/PageDirectory.cpp
+++ b/Kernel/Arch/riscv64/PageDirectory.cpp
@@ -8,39 +8,84 @@
 #include <AK/Singleton.h>
 
 #include <Kernel/Arch/PageDirectory.h>
+#include <Kernel/Interrupts/InterruptDisabler.h>
 #include <Kernel/Library/LockRefPtr.h>
 #include <Kernel/Sections.h>
+#include <Kernel/Tasks/Process.h>
+#include <Kernel/Tasks/Thread.h>
 
 namespace Kernel::Memory {
 
-void PageDirectory::register_page_directory(PageDirectory*)
+struct SATPMap {
+    SpinlockProtected<IntrusiveRedBlackTree<&PageDirectory::m_tree_node>, LockRank::None> map {};
+};
+
+static Singleton<SATPMap> s_satp_map;
+
+void PageDirectory::register_page_directory(PageDirectory* page_directory)
 {
-    TODO_RISCV64();
+    s_satp_map->map.with([&](auto& map) {
+        map.insert(bit_cast<FlatPtr>(page_directory->satp()), *page_directory);
+    });
 }
 
-void PageDirectory::deregister_page_directory(PageDirectory*)
+void PageDirectory::deregister_page_directory(PageDirectory* page_directory)
 {
-    TODO_RISCV64();
+    s_satp_map->map.with([&](auto& map) {
+        map.remove(bit_cast<FlatPtr>(page_directory->satp()));
+    });
 }
 
-ErrorOr<NonnullLockRefPtr<PageDirectory>> PageDirectory::try_create_for_userspace(Process&)
+ErrorOr<NonnullLockRefPtr<PageDirectory>> PageDirectory::try_create_for_userspace(Process& process)
 {
-    TODO_RISCV64();
+    auto directory = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) PageDirectory));
+
+    directory->m_process = &process;
+
+    directory->m_directory_table = TRY(MM.allocate_physical_page());
+    auto kernel_pd_index = (kernel_mapping_base >> VPN_2_OFFSET) & PAGE_TABLE_INDEX_MASK;
+    for (size_t i = 0; i < kernel_pd_index; i++) {
+        directory->m_directory_pages[i] = TRY(MM.allocate_physical_page());
+    }
+
+    // Share the top 1 GiB of kernel-only mappings (>=kernel_mapping_base)
+    directory->m_directory_pages[kernel_pd_index] = MM.kernel_page_directory().m_directory_pages[kernel_pd_index];
+
+    {
+        InterruptDisabler disabler;
+        auto& table = *reinterpret_cast<PageDirectoryPointerTable*>(MM.quickmap_page(*directory->m_directory_table));
+        for (size_t i = 0; i < array_size(directory->m_directory_pages); i++) {
+            if (directory->m_directory_pages[i] != nullptr) {
+                table.raw[i] = ((directory->m_directory_pages[i]->paddr().get()) >> PADDR_PPN_OFFSET) << PTE_PPN_OFFSET;
+                table.raw[i] |= to_underlying(PageTableEntryBits::Valid);
+            }
+        }
+        MM.unquickmap_page();
+    }
+
+    register_page_directory(directory);
+    return directory;
 }
 
 LockRefPtr<PageDirectory> PageDirectory::find_current()
 {
-    TODO_RISCV64();
+    return s_satp_map->map.with([&](auto& map) {
+        return map.find(bit_cast<FlatPtr>(RISCV64::CSR::SATP::read()));
+    });
 }
 
-void activate_kernel_page_directory(PageDirectory const&)
+void activate_kernel_page_directory(PageDirectory const& page_directory)
 {
-    TODO_RISCV64();
+    RISCV64::CSR::SATP::write(page_directory.satp());
+    Processor::flush_entire_tlb_local();
 }
 
-void activate_page_directory(PageDirectory const&, Thread*)
+void activate_page_directory(PageDirectory const& page_directory, Thread* thread)
 {
-    TODO_RISCV64();
+    auto const satp = page_directory.satp();
+    thread->regs().satp = satp;
+    RISCV64::CSR::SATP::write(satp);
+    Processor::flush_entire_tlb_local();
 }
 
 UNMAP_AFTER_INIT NonnullLockRefPtr<PageDirectory> PageDirectory::must_create_kernel_page_directory()
@@ -52,7 +97,10 @@ PageDirectory::PageDirectory() = default;
 
 UNMAP_AFTER_INIT void PageDirectory::allocate_kernel_directory()
 {
-    TODO_RISCV64();
+    dmesgln("MM: boot_pdpt @ {}", boot_pdpt);
+    dmesgln("MM: boot_pd_kernel @ {}", boot_pd_kernel);
+    m_directory_table = PhysicalPage::create(boot_pdpt, MayReturnToFreeList::No);
+    m_directory_pages[(kernel_mapping_base >> VPN_2_OFFSET) & PAGE_TABLE_INDEX_MASK] = PhysicalPage::create(boot_pd_kernel, MayReturnToFreeList::No);
 }
 
 PageDirectory::~PageDirectory()