kernel: Rename UserVM to AddressSpace

This is a more appropriate name now that it does more stuff than allocate virtual memory.

To be fair, the name was a bit awkward anyway. Should have been UserVMAllocator I guess.

kernel/CMakeLists.txt

@@ -12,7 +12,7 @@ set(SOURCES
     src/memory/MemoryManager.cpp
     src/memory/Heap.cpp
     src/memory/KernelVM.cpp
-    src/memory/UserVM.cpp
+    src/memory/AddressSpace.cpp
     src/memory/MemoryMap.cpp
     src/boot/Init.cpp
     src/arch/Serial.cpp

kernel/src/memory/AddressSpace.cpp

@@ -1,4 +1,4 @@
-#include "memory/UserVM.h"
+#include "memory/AddressSpace.h"
 #include "Log.h"
 #include "arch/MMU.h"
 #include "memory/Heap.h"
@@ -8,17 +8,19 @@
 static constexpr u64 VM_START = ARCH_PAGE_SIZE;
 static constexpr u64 VM_END = 0x0000800000000000;
 
-Result<OwnedPtr<UserVM>> UserVM::try_create()
+Result<OwnedPtr<AddressSpace>> AddressSpace::try_create()
 {
-    OwnedPtr<UserVM> ptr = TRY(make_owned<UserVM>());
+    OwnedPtr<AddressSpace> ptr = TRY(make_owned<AddressSpace>());
 
     TRY(ptr->create_null_region());
     TRY(ptr->create_default_region());
 
+    ptr->m_directory = TRY(MMU::create_page_directory_for_userspace());
+
     return move(ptr);
 }
 
-Result<void> UserVM::create_null_region()
+Result<void> AddressSpace::create_null_region()
 {
     // Create a small region at the start of the address space to prevent anyone from mapping page 0.
     auto* region = TRY(make<VMRegion>());
@@ -31,7 +33,7 @@ Result<void> UserVM::create_null_region()
     return {};
 }
 
-Result<void> UserVM::create_default_region()
+Result<void> AddressSpace::create_default_region()
 {
     // Create a free region covering the rest of the address space.
     auto* region = TRY(make<VMRegion>());
@@ -43,9 +45,9 @@ Result<void> UserVM::create_default_region()
     return {};
 }
 
-Result<OwnedPtr<UserVM>> UserVM::clone()
+Result<OwnedPtr<AddressSpace>> AddressSpace::clone()
 {
-    OwnedPtr<UserVM> ptr = TRY(make_owned<UserVM>());
+    OwnedPtr<AddressSpace> ptr = TRY(make_owned<AddressSpace>());
 
     for (const auto* region : m_regions)
     {
@@ -54,14 +56,29 @@ Result<OwnedPtr<UserVM>> UserVM::clone()
         ptr->m_regions.append(new_region);
     }
 
+    ptr->m_directory = TRY(MMU::clone_userspace_page_directory(m_directory));
+
     return move(ptr);
 }
 
-UserVM::UserVM()
+AddressSpace::AddressSpace()
 {
 }
 
-Result<u64> UserVM::alloc_region(usize count, bool persistent)
+AddressSpace& AddressSpace::operator=(AddressSpace&& other)
+{
+    if (&other == this) return *this;
+
+    m_regions.consume([](VMRegion* region) { delete region; });
+    MMU::delete_userspace_page_directory(m_directory);
+
+    m_regions = other.m_regions;
+    m_directory = other.m_directory;
+
+    return *this;
+}
+
+Result<u64> AddressSpace::alloc_region(usize count, bool persistent)
 {
     for (auto* region = m_regions.expect_last(); region; region = m_regions.previous(region).value_or(nullptr))
     {
@@ -91,7 +108,7 @@ Result<u64> UserVM::alloc_region(usize count, bool persistent)
     return err(ENOMEM);
 }
 
-Result<bool> UserVM::set_region(u64 address, usize count, bool used, bool persistent)
+Result<bool> AddressSpace::set_region(u64 address, usize count, bool used, bool persistent)
 {
     if (address >= VM_END) return err(EINVAL);
 
@@ -154,7 +171,7 @@ Result<bool> UserVM::set_region(u64 address, usize count, bool used, bool persis
     return true;
 }
 
-void UserVM::merge_contiguous_regions(VMRegion* a, VMRegion* b)
+void AddressSpace::merge_contiguous_regions(VMRegion* a, VMRegion* b)
 {
     a->end = b->end;
     a->count += b->count;
@@ -162,7 +179,7 @@ void UserVM::merge_contiguous_regions(VMRegion* a, VMRegion* b)
     delete b;
 }
 
-void UserVM::try_merge_region_with_neighbors(VMRegion* region)
+void AddressSpace::try_merge_region_with_neighbors(VMRegion* region)
 {
     auto prev = m_regions.previous(region);
     if (prev.has_value() && (*prev)->used == region->used && (*prev)->persistent == region->persistent)
@@ -178,7 +195,7 @@ void UserVM::try_merge_region_with_neighbors(VMRegion* region)
     }
 }
 
-Result<VMRegion*> UserVM::split_region(VMRegion* parent, u64 boundary)
+Result<VMRegion*> AddressSpace::split_region(VMRegion* parent, u64 boundary)
 {
     auto* region = TRY(make<VMRegion>());
 
@@ -195,7 +212,8 @@ Result<VMRegion*> UserVM::split_region(VMRegion* parent, u64 boundary)
     return region;
 }
 
-UserVM::~UserVM()
+AddressSpace::~AddressSpace()
 {
     m_regions.consume([](VMRegion* region) { delete region; });
+    MMU::delete_userspace_page_directory(m_directory);
 }

kernel/src/memory/AddressSpace.h

@@ -1,4 +1,5 @@
 #pragma once
+#include "arch/MMU.h"
 #include <luna/LinkedList.h>
 #include <luna/OwnedPtr.h>
 #include <luna/Result.h>
@@ -13,11 +14,13 @@ class VMRegion : LinkedListNode<VMRegion>
     bool persistent { false };
 };
 
-class UserVM
+class AddressSpace
 {
   public:
-    UserVM();
+    AddressSpace();
-    ~UserVM();
+    ~AddressSpace();
+
+    AddressSpace& operator=(AddressSpace&& other);
 
     Result<u64> alloc_region(usize count, bool persistent = false);
 
@@ -31,9 +34,14 @@ class UserVM
         return set_region(address, count, false, false);
     }
 
-    static Result<OwnedPtr<UserVM>> try_create();
+    static Result<OwnedPtr<AddressSpace>> try_create();
 
-    Result<OwnedPtr<UserVM>> clone();
+    Result<OwnedPtr<AddressSpace>> clone();
+
+    PageDirectory* page_directory() const
+    {
+        return m_directory;
+    }
 
   private:
     Result<bool> set_region(u64 address, usize count, bool used, bool persistent);
@@ -42,5 +50,7 @@ class UserVM
     void try_merge_region_with_neighbors(VMRegion* region);
     void merge_contiguous_regions(VMRegion* a, VMRegion* b);
     Result<VMRegion*> split_region(VMRegion* parent, u64 boundary);
+
     LinkedList<VMRegion> m_regions;
+    PageDirectory* m_directory;
 };

kernel/src/sys/exec.cpp

@@ -70,7 +70,7 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
     kdbgln("exec: attempting to replace current image with %s", path.chars());
 #endif
 
-    auto guard = make_scope_guard([current] { MMU::switch_page_directory(current->self_directory); });
+    auto guard = make_scope_guard([current] { MMU::switch_page_directory(current->self_directory()); });
 
     auto image = TRY(ThreadImage::try_load_from_elf(inode));
 
@@ -99,8 +99,6 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
         }
     }
 
-    MMU::delete_userspace_page_directory(current->self_directory);
-
     if (VFS::is_setuid(inode)) current->auth.euid = current->auth.suid = inode->uid();
     if (VFS::is_setgid(inode)) current->auth.egid = current->auth.sgid = inode->gid();
 
@@ -108,7 +106,7 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
 
     image->apply(current);
 
-    MMU::switch_page_directory(current->self_directory);
+    MMU::switch_page_directory(current->self_directory());
 
     current->set_arguments(user_argc, user_argv, user_envc, user_envp);
 
@@ -123,7 +121,7 @@ Result<u64> sys_fork(Registers* regs, SyscallArgs)
 {
     auto current = Scheduler::current();
 
-    auto guard = make_scope_guard([current] { MMU::switch_page_directory(current->self_directory); });
+    auto guard = make_scope_guard([current] { MMU::switch_page_directory(current->self_directory()); });
 
     memcpy(&current->regs, regs, sizeof(*regs));
 

kernel/src/sys/mmap.cpp

@@ -37,12 +37,12 @@ Result<u64> sys_mmap(Registers*, SyscallArgs args)
     Thread* current = Scheduler::current();
 
     u64 address;
-    if (!addr) address = TRY(current->vm_allocator->alloc_region(get_blocks_from_size(len, ARCH_PAGE_SIZE)));
+    if (!addr) address = TRY(current->address_space->alloc_region(get_blocks_from_size(len, ARCH_PAGE_SIZE)));
     else
     {
         // FIXME: We should be more flexible if MAP_FIXED was not specified.
         address = align_down<ARCH_PAGE_SIZE>((u64)addr);
-        if (!TRY(current->vm_allocator->test_and_alloc_region(address, get_blocks_from_size(len, ARCH_PAGE_SIZE))))
+        if (!TRY(current->address_space->test_and_alloc_region(address, get_blocks_from_size(len, ARCH_PAGE_SIZE))))
             return err(ENOMEM);
     }
 
@@ -69,7 +69,7 @@ Result<u64> sys_munmap(Registers*, SyscallArgs args)
 
     Thread* current = Scheduler::current();
 
-    bool ok = TRY(current->vm_allocator->free_region(address, get_blocks_from_size(size, ARCH_PAGE_SIZE)));
+    bool ok = TRY(current->address_space->free_region(address, get_blocks_from_size(size, ARCH_PAGE_SIZE)));
 
     // POSIX says munmap should silently do nothing if the memory was not already mapped.
     if (!ok) return 0;

kernel/src/thread/ELF.cpp

@@ -25,7 +25,7 @@ static bool can_write_segment(u32 flags)
 
 namespace ELFLoader
 {
-    Result<ELFData> load(SharedPtr<VFS::Inode> inode, UserVM* vm)
+    Result<ELFData> load(SharedPtr<VFS::Inode> inode, AddressSpace* space)
     {
         Elf64_Ehdr elf_header;
         usize nread = TRY(inode->read((u8*)&elf_header, 0, sizeof elf_header));
@@ -102,7 +102,7 @@ namespace ELFLoader
                 if (can_write_segment(program_header.p_flags)) flags |= MMU::ReadWrite;
                 if (can_execute_segment(program_header.p_flags)) flags &= ~MMU::NoExecute;
 
-                if (!TRY(vm->test_and_alloc_region(
+                if (!TRY(space->test_and_alloc_region(
                         base_vaddr, get_blocks_from_size(program_header.p_memsz + vaddr_diff, ARCH_PAGE_SIZE), true)))
                     return err(ENOMEM);
 

kernel/src/thread/ELF.h

@@ -1,6 +1,6 @@
 #pragma once
 #include "fs/VFS.h"
-#include "memory/UserVM.h"
+#include "memory/AddressSpace.h"
 #include <luna/Types.h>
 
 #define ELFMAG "\177ELF"
@@ -54,5 +54,5 @@ struct ELFData
 
 namespace ELFLoader
 {
-    Result<ELFData> load(SharedPtr<VFS::Inode> inode, UserVM* vm);
+    Result<ELFData> load(SharedPtr<VFS::Inode> inode, AddressSpace* space);
 };

kernel/src/thread/Scheduler.cpp

@@ -191,8 +191,6 @@ namespace Scheduler
             }
         }
 
-        if (!thread->is_kernel) MMU::delete_userspace_page_directory(thread->self_directory);
-
         delete thread;
 
         CPU::enable_interrupts();

kernel/src/thread/Thread.h

@@ -2,7 +2,7 @@
 
 #include "arch/MMU.h"
 #include "fs/VFS.h"
-#include "memory/UserVM.h"
+#include "memory/AddressSpace.h"
 #include <luna/LinkedList.h>
 #include <luna/OwnedPtr.h>
 #include <luna/Result.h>
@@ -70,7 +70,7 @@ struct Thread : public LinkedListNode<Thread>
     Stack stack;
     Stack kernel_stack;
 
-    OwnedPtr<UserVM> vm_allocator;
+    OwnedPtr<AddressSpace> address_space;
     Option<FileDescriptor> fd_table[FD_MAX] = {};
 
     Result<int> allocate_fd(int min);
@@ -97,7 +97,11 @@ struct Thread : public LinkedListNode<Thread>
     Thread* parent { nullptr };
     Option<pid_t> child_being_waited_for = {};
 
-    PageDirectory* self_directory;
+    PageDirectory* self_directory() const
+    {
+        return address_space->page_directory();
+    }
+
     PageDirectory* active_directory { nullptr };
 
     [[noreturn]] void exit_and_signal_parent(u8 status);

kernel/src/thread/ThreadImage.cpp

@@ -7,11 +7,11 @@
 static constexpr usize DEFAULT_USER_STACK_PAGES = 6;
 static constexpr usize DEFAULT_USER_STACK_SIZE = DEFAULT_USER_STACK_PAGES * ARCH_PAGE_SIZE;
 
-static Result<void> create_stacks(Stack& user_stack, Stack& kernel_stack, UserVM* vm)
+static Result<void> create_stacks(Stack& user_stack, Stack& kernel_stack, AddressSpace* space)
 {
     const u64 THREAD_STACK_BASE = 0x10000;
 
-    if (!TRY(vm->test_and_alloc_region(THREAD_STACK_BASE, DEFAULT_USER_STACK_PAGES, true))) return err(ENOMEM);
+    if (!TRY(space->test_and_alloc_region(THREAD_STACK_BASE, DEFAULT_USER_STACK_PAGES, true))) return err(ENOMEM);
 
     TRY(MemoryManager::alloc_at_zeroed(THREAD_STACK_BASE, DEFAULT_USER_STACK_PAGES,
                                        MMU::ReadWrite | MMU::NoExecute | MMU::User));
@@ -32,32 +32,26 @@ Result<OwnedPtr<ThreadImage>> ThreadImage::try_load_from_elf(SharedPtr<VFS::Inod
 {
     auto image = TRY(make_owned<ThreadImage>());
 
-    auto vm_allocator = TRY(UserVM::try_create());
+    auto address_space = TRY(AddressSpace::try_create());
 
     auto old_directory = MMU::get_page_directory();
 
-    auto new_directory = TRY(MMU::create_page_directory_for_userspace());
+    MMU::switch_page_directory(address_space->page_directory());
 
-    MMU::switch_page_directory(new_directory);
+    auto guard = make_scope_guard([=] { MMU::switch_page_directory(old_directory); });
 
-    auto guard = make_scope_guard([=] {
+    const ELFData data = TRY(ELFLoader::load(inode, address_space.ptr()));
-        MMU::delete_userspace_page_directory(new_directory);
-        MMU::switch_page_directory(old_directory);
-    });
-
-    const ELFData data = TRY(ELFLoader::load(inode, vm_allocator.ptr()));
 
     Stack user_stack;
     Stack kernel_stack;
-    TRY(create_stacks(user_stack, kernel_stack, vm_allocator.ptr()));
+    TRY(create_stacks(user_stack, kernel_stack, address_space.ptr()));
 
     guard.deactivate();
 
-    image->m_directory = new_directory;
     image->m_kernel_stack = kernel_stack;
     image->m_user_stack = user_stack;
     image->m_loaded_image_data = data;
-    image->m_vm_allocator = move(vm_allocator);
+    image->m_address_space = move(address_space);
     image->m_sp = user_stack.top();
 
     return image;
@@ -67,20 +61,17 @@ Result<OwnedPtr<ThreadImage>> ThreadImage::clone_from_thread(Thread* parent)
 {
     auto image = TRY(make_owned<ThreadImage>());
 
-    auto vm_allocator = TRY(parent->vm_allocator->clone());
+    auto address_space = TRY(parent->address_space->clone());
-
-    auto new_directory = TRY(MMU::clone_userspace_page_directory(parent->self_directory));
 
     const ELFData data = { .entry = parent->ip() };
 
     const u64 kernel_stack_base = TRY(MemoryManager::alloc_for_kernel(4, MMU::ReadWrite | MMU::NoExecute));
     Stack kernel_stack { kernel_stack_base, 4 * ARCH_PAGE_SIZE };
 
-    image->m_directory = new_directory;
     image->m_kernel_stack = kernel_stack;
     image->m_user_stack = parent->stack;
     image->m_loaded_image_data = data;
-    image->m_vm_allocator = move(vm_allocator);
+    image->m_address_space = move(address_space);
     image->m_sp = parent->sp();
 
     return image;
@@ -124,8 +115,7 @@ void ThreadImage::apply(Thread* thread)
     thread->stack = m_user_stack;
     thread->set_sp(align_down<16>(m_sp));
 
-    thread->self_directory = m_directory;
+    thread->active_directory = m_address_space->page_directory();
-    thread->active_directory = m_directory;
 
-    thread->vm_allocator = move(m_vm_allocator);
+    thread->address_space = move(m_address_space);
 }

kernel/src/thread/ThreadImage.h

@@ -4,7 +4,7 @@
 #include "arch/CPU.h"
 #include "arch/MMU.h"
 #include "fs/VFS.h"
-#include "memory/UserVM.h"
+#include "memory/AddressSpace.h"
 #include "thread/Thread.h"
 #include <luna/LinkedList.h>
 #include <luna/OwnedPtr.h>
@@ -28,8 +28,7 @@ class ThreadImage
     void apply(Thread* thread);
 
   private:
-    OwnedPtr<UserVM> m_vm_allocator;
+    OwnedPtr<AddressSpace> m_address_space;
-    PageDirectory* m_directory { nullptr };
     Stack m_user_stack;
     Stack m_kernel_stack;
     ELFData m_loaded_image_data;