Kernel: Steer away from heap allocations for ProcFS process data

Instead, use more static patterns to acquire that sort of data.

Documentation/Kernel/ProcFSIndexing.md

@@ -0,0 +1,71 @@
+# ProcFS Indexing
+
+## Is a ProcFS index deterministic value?
+
+Short answer - yes. Long answer - because of the design pattern that was chosen,
+each `InodeIndex` actually represent a known object, so it is guaranteed to be
+the same always for global ProcFS objects. For process ID directories, once that
+process has been killed, its primary segment value is no longer valid and hence
+all sub-segments of it are not relevant anymore, but if the process is still alive,
+it is guaranteed that accessing the same `InodeIndex` in regard to a object tied to
+a process directory will provide the expected object.
+
+## The goal - zero allocations when creating new process
+
+The main goal is to have zero allocations happening in ProcFS when a new process is created.
+The old ProcFS design followed that principle, but was quite hard to edit and to extend with new
+functionality.
+The current ProcFS design doesn't follow that principle, but is easier to edit and to extend.
+A compromise is needed to ensure we get the advantages from both designs while minimizing the
+effects of the disadvantages of each design.
+
+## The segmeneted index
+
+### The layout of the segmented index
+
+Since it was decided that heap allocations for ProcFS are *mostly* bad, the new
+design layout tries to achieve most of the principle of "Don't allocate anything
+until actually needed". For that to happen, `InodeIndex` (u64 value) is splitted
+to 3 Segments:
+- The primary segment: value 0 is reserved for all non-PID inodes in the procfs.
+All values from 1 to 0xFFFFFFF are valid PID indices, which represents all PIDs from 0 to 0xFFFFFFE
+
+- The Sub-directory segment: value 0 is reserved for parent PID directory. All other values are
+available for usage of subdirectories in the PID directory.
+
+- The property segment: value 0 is reserved for parent PID directory. All other values are
+available for usage of components in the PID directory or in subdirectories of the PID directory.
+
+So, the final layout of the 64 bit index is:
+
+```
+| Primary Segment (28 bits) | Sub-directory (16 bits) | Component (20 bits) |
+```
+
+Example: To find a Thread 0 stack, for PID 1, the following encoding is applied:
+
+```
+hex(2 << 16 | 2 << (16 + 28)) == 0x200000020000
+```
+
+### Two rules for indexing
+
+We don't want to allocate anything when a process is created, but we still want
+to allocate global objects, so it's somewhat a compromise between two conflicting targets.
+To do that we need to ensure that:
+
+1. If the primary segment value equals to 0, then the sub-directory and property segmentation
+is not applied, but a sequential indexing is determined instead. This is needed so ProcFS can still
+use global components that were pre-allocated beforehand. This means that there might be up to 
+68719476735 global components (including global sub-directories objects) in the ProcFS.
+Otherwise, for every primary segment value > 0, then the sub-directory and property segmentation
+is applied. This means that there might be up to 65534 sub-directories in a PID directory, and
+up to 1048575 (1048574 for PID directory) properties (objects) in each sub-directory.
+
+2. If the primary segment value equals to 0, then value 0 in both aritificial sub-directory 
+and property segments represents the root ProcFS folder.
+Otherwise, for every primary segment value > 0, value 0 in both sub-directory and
+property segments are reserved to represent the root PID directory.
+Please note that if the sub-directory segment > 0, and property segment = 0 is a valid
+index, and represents a valid property object in that sub-directory.
+

Kernel/FileSystem/ProcFS.cpp

@@ -13,6 +13,7 @@
 #include <Kernel/FileSystem/ProcFS.h>
 #include <Kernel/FileSystem/VirtualFileSystem.h>
 #include <Kernel/Heap/kmalloc.h>
+#include <Kernel/Process.h>
 #include <Kernel/Sections.h>
 #include <LibC/errno_numbers.h>
 
@@ -36,25 +37,16 @@ UNMAP_AFTER_INIT ProcFSComponentRegistry::ProcFSComponentRegistry()
 {
 }
 
-void ProcFSComponentRegistry::register_new_process(Process& new_process)
-{
-    MutexLocker locker(m_lock);
-    m_root_directory->m_process_directories.append(ProcFSProcessDirectory::create(new_process));
-}
-
-void ProcFSComponentRegistry::unregister_process(Process& deleted_process)
-{
-    auto process_directory = m_root_directory->process_directory_for(deleted_process).release_nonnull();
-    process_directory->prepare_for_deletion();
-    process_directory->m_list_node.remove();
-    dbgln_if(PROCFS_DEBUG, "ProcFSExposedDirectory ref_count now: {}", process_directory->ref_count());
-}
-
 RefPtr<ProcFS> ProcFS::create()
 {
     return adopt_ref_if_nonnull(new (nothrow) ProcFS);
 }
 
+ProcFS::ProcFS()
+    : m_root_inode(ProcFSComponentRegistry::the().root_directory().to_inode(*this))
+{
+}
+
 ProcFS::~ProcFS()
 {
 }
@@ -69,90 +61,25 @@ Inode& ProcFS::root_inode()
     return *m_root_inode;
 }
 
-NonnullRefPtr<ProcFSInode> ProcFSInode::create(const ProcFS& fs, const ProcFSExposedComponent& component)
+ProcFSInode::ProcFSInode(const ProcFS& fs, InodeIndex index)
+    : Inode(const_cast<ProcFS&>(fs), index)
 {
-    return adopt_ref(*new (nothrow) ProcFSInode(fs, component));
-}
-
-ProcFSInode::ProcFSInode(const ProcFS& fs, const ProcFSExposedComponent& component)
-    : Inode(const_cast<ProcFS&>(fs), component.component_index())
-    , m_associated_component(component)
-{
-}
-
-KResult ProcFSInode::attach(FileDescription& description)
-{
-    return m_associated_component->refresh_data(description);
-}
-
-void ProcFSInode::did_seek(FileDescription& description, off_t new_offset)
-{
-    if (new_offset != 0)
-        return;
-    auto result = m_associated_component->refresh_data(description);
-    if (result.is_error()) {
-        // Subsequent calls to read will return EIO!
-        dbgln("ProcFS: Could not refresh contents: {}", result.error());
-    }
 }
 
 ProcFSInode::~ProcFSInode()
 {
 }
 
-ProcFS::ProcFS()
-    : m_root_inode(ProcFSComponentRegistry::the().root_directory().to_inode(*this))
-{
-}
-
-KResultOr<size_t> ProcFSInode::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, FileDescription* fd) const
-{
-    return m_associated_component->read_bytes(offset, count, buffer, fd);
-}
-
-StringView ProcFSInode::name() const
-{
-    return m_associated_component->name();
-}
-
-KResult ProcFSInode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const
-{
-    VERIFY_NOT_REACHED();
-}
-
-RefPtr<Inode> ProcFSInode::lookup(StringView)
-{
-    VERIFY_NOT_REACHED();
-}
-
-InodeMetadata ProcFSInode::metadata() const
-{
-    MutexLocker locker(m_inode_lock);
-    InodeMetadata metadata;
-    metadata.inode = { fsid(), m_associated_component->component_index() };
-    metadata.mode = S_IFREG | m_associated_component->required_mode();
-    metadata.uid = m_associated_component->owner_user();
-    metadata.gid = m_associated_component->owner_group();
-    metadata.size = m_associated_component->size();
-    metadata.mtime = m_associated_component->modified_time();
-    return metadata;
-}
-
 void ProcFSInode::flush_metadata()
 {
 }
 
-KResultOr<size_t> ProcFSInode::write_bytes(off_t offset, size_t count, const UserOrKernelBuffer& buffer, FileDescription* fd)
+KResult ProcFSInode::add_child(Inode&, const StringView&, mode_t)
-{
-    return m_associated_component->write_bytes(offset, count, buffer, fd);
-}
-
-KResultOr<NonnullRefPtr<Inode>> ProcFSInode::create_child(StringView, mode_t, dev_t, uid_t, gid_t)
 {
     return EROFS;
 }
 
-KResult ProcFSInode::add_child(Inode&, const StringView&, mode_t)
+KResultOr<NonnullRefPtr<Inode>> ProcFSInode::create_child(StringView, mode_t, dev_t, uid_t, gid_t)
 {
     return EROFS;
 }
@@ -177,13 +104,78 @@ KResult ProcFSInode::truncate(u64)
     return EPERM;
 }
 
+NonnullRefPtr<ProcFSGlobalInode> ProcFSGlobalInode::create(const ProcFS& fs, const ProcFSExposedComponent& component)
+{
+    return adopt_ref(*new (nothrow) ProcFSGlobalInode(fs, component));
+}
+
+ProcFSGlobalInode::ProcFSGlobalInode(const ProcFS& fs, const ProcFSExposedComponent& component)
+    : ProcFSInode(fs, component.component_index())
+    , m_associated_component(component)
+{
+}
+
+void ProcFSGlobalInode::did_seek(FileDescription& description, off_t new_offset)
+{
+    if (new_offset != 0)
+        return;
+    auto result = m_associated_component->refresh_data(description);
+    if (result.is_error()) {
+        // Subsequent calls to read will return EIO!
+        dbgln("ProcFS: Could not refresh contents: {}", result.error());
+    }
+}
+
+KResult ProcFSGlobalInode::attach(FileDescription& description)
+{
+    return m_associated_component->refresh_data(description);
+}
+
+KResultOr<size_t> ProcFSGlobalInode::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, FileDescription* fd) const
+{
+    return m_associated_component->read_bytes(offset, count, buffer, fd);
+}
+
+StringView ProcFSGlobalInode::name() const
+{
+    return m_associated_component->name();
+}
+
+KResult ProcFSGlobalInode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const
+{
+    VERIFY_NOT_REACHED();
+}
+
+RefPtr<Inode> ProcFSGlobalInode::lookup(StringView)
+{
+    VERIFY_NOT_REACHED();
+}
+
+InodeMetadata ProcFSGlobalInode::metadata() const
+{
+    MutexLocker locker(m_inode_lock);
+    InodeMetadata metadata;
+    metadata.inode = { fsid(), m_associated_component->component_index() };
+    metadata.mode = S_IFREG | m_associated_component->required_mode();
+    metadata.uid = m_associated_component->owner_user();
+    metadata.gid = m_associated_component->owner_group();
+    metadata.size = m_associated_component->size();
+    metadata.mtime = m_associated_component->modified_time();
+    return metadata;
+}
+
+KResultOr<size_t> ProcFSGlobalInode::write_bytes(off_t offset, size_t count, const UserOrKernelBuffer& buffer, FileDescription* fd)
+{
+    return m_associated_component->write_bytes(offset, count, buffer, fd);
+}
+
 NonnullRefPtr<ProcFSDirectoryInode> ProcFSDirectoryInode::create(const ProcFS& procfs, const ProcFSExposedComponent& component)
 {
     return adopt_ref(*new (nothrow) ProcFSDirectoryInode(procfs, component));
 }
 
 ProcFSDirectoryInode::ProcFSDirectoryInode(const ProcFS& fs, const ProcFSExposedComponent& component)
-    : ProcFSInode(fs, component)
+    : ProcFSGlobalInode(fs, component)
 {
 }
 
@@ -204,17 +196,17 @@ InodeMetadata ProcFSDirectoryInode::metadata() const
 }
 KResult ProcFSDirectoryInode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    MutexLocker locker(fs().m_lock);
+    MutexLocker locker(procfs().m_lock);
-    return m_associated_component->traverse_as_directory(fs().fsid(), move(callback));
+    return m_associated_component->traverse_as_directory(procfs().fsid(), move(callback));
 }
 
 RefPtr<Inode> ProcFSDirectoryInode::lookup(StringView name)
 {
-    MutexLocker locker(fs().m_lock);
+    MutexLocker locker(procfs().m_lock);
     auto component = m_associated_component->lookup(name);
     if (!component)
         return {};
-    return component->to_inode(fs());
+    return component->to_inode(procfs());
 }
 
 NonnullRefPtr<ProcFSLinkInode> ProcFSLinkInode::create(const ProcFS& procfs, const ProcFSExposedComponent& component)
@@ -223,9 +215,10 @@ NonnullRefPtr<ProcFSLinkInode> ProcFSLinkInode::create(const ProcFS& procfs, con
 }
 
 ProcFSLinkInode::ProcFSLinkInode(const ProcFS& fs, const ProcFSExposedComponent& component)
-    : ProcFSInode(fs, component)
+    : ProcFSGlobalInode(fs, component)
 {
 }
+
 InodeMetadata ProcFSLinkInode::metadata() const
 {
     MutexLocker locker(m_inode_lock);
@@ -239,4 +232,364 @@ InodeMetadata ProcFSLinkInode::metadata() const
     return metadata;
 }
 
+ProcFSProcessAssociatedInode::ProcFSProcessAssociatedInode(const ProcFS& fs, ProcessID associated_pid, InodeIndex determined_index)
+    : ProcFSInode(fs, determined_index)
+    , m_pid(associated_pid)
+{
+}
+
+KResultOr<size_t> ProcFSProcessAssociatedInode::write_bytes(off_t, size_t, const UserOrKernelBuffer&, FileDescription*)
+{
+    VERIFY_NOT_REACHED();
+}
+
+NonnullRefPtr<ProcFSProcessDirectoryInode> ProcFSProcessDirectoryInode::create(const ProcFS& procfs, ProcessID pid)
+{
+    return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessDirectoryInode(procfs, pid)).release_nonnull();
+}
+
+ProcFSProcessDirectoryInode::ProcFSProcessDirectoryInode(const ProcFS& procfs, ProcessID pid)
+    : ProcFSProcessAssociatedInode(procfs, pid, SegmentedProcFSIndex::build_segmented_index_for_pid_directory(pid))
+{
+}
+
+KResult ProcFSProcessDirectoryInode::attach(FileDescription&)
+{
+    return KSuccess;
+}
+
+InodeMetadata ProcFSProcessDirectoryInode::metadata() const
+{
+    MutexLocker locker(m_inode_lock);
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return {};
+    InodeMetadata metadata;
+    metadata.inode = { fsid(), process->component_index() };
+    metadata.mode = S_IFDIR | process->required_mode();
+    metadata.uid = process->owner_user();
+    metadata.gid = process->owner_group();
+    metadata.size = 0;
+    metadata.mtime = process->modified_time();
+    return metadata;
+}
+
+KResultOr<size_t> ProcFSProcessDirectoryInode::read_bytes(off_t, size_t, UserOrKernelBuffer&, FileDescription*) const
+{
+    VERIFY_NOT_REACHED();
+}
+
+KResult ProcFSProcessDirectoryInode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
+{
+    MutexLocker locker(procfs().m_lock);
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return EINVAL;
+    return process->traverse_as_directory(procfs().fsid(), move(callback));
+}
+
+RefPtr<Inode> ProcFSProcessDirectoryInode::lookup(StringView name)
+{
+    MutexLocker locker(procfs().m_lock);
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return nullptr;
+    if (name == "fd")
+        return ProcFSProcessSubDirectoryInode::create(procfs(), SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions, associated_pid());
+    if (name == "stacks")
+        return ProcFSProcessSubDirectoryInode::create(procfs(), SegmentedProcFSIndex::ProcessSubDirectory::Stacks, associated_pid());
+    if (name == "unveil")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::Unveil, associated_pid());
+    if (name == "pledge")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::Pledge, associated_pid());
+    if (name == "fds")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::FileDescriptions, associated_pid());
+    if (name == "exe")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::BinaryLink, associated_pid());
+    if (name == "cwd")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::CurrentWorkDirectoryLink, associated_pid());
+    if (name == "perf_events")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::PerformanceEvents, associated_pid());
+    if (name == "vm")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::VirtualMemoryStats, associated_pid());
+    if (name == "root")
+        return ProcFSProcessPropertyInode::create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::RootLink, associated_pid());
+    return nullptr;
+}
+
+NonnullRefPtr<ProcFSProcessSubDirectoryInode> ProcFSProcessSubDirectoryInode::create(const ProcFS& procfs, SegmentedProcFSIndex::ProcessSubDirectory sub_directory_type, ProcessID pid)
+{
+    return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessSubDirectoryInode(procfs, sub_directory_type, pid)).release_nonnull();
+}
+
+ProcFSProcessSubDirectoryInode::ProcFSProcessSubDirectoryInode(const ProcFS& procfs, SegmentedProcFSIndex::ProcessSubDirectory sub_directory_type, ProcessID pid)
+    : ProcFSProcessAssociatedInode(procfs, pid, SegmentedProcFSIndex::build_segmented_index_for_sub_directory(pid, sub_directory_type))
+    , m_sub_directory_type(sub_directory_type)
+{
+}
+
+KResultOr<size_t> ProcFSProcessSubDirectoryInode::read_bytes(off_t, size_t, UserOrKernelBuffer&, FileDescription*) const
+{
+    VERIFY_NOT_REACHED();
+}
+
+KResult ProcFSProcessSubDirectoryInode::attach(FileDescription&)
+{
+    return KSuccess;
+}
+
+void ProcFSProcessSubDirectoryInode::did_seek(FileDescription&, off_t)
+{
+    VERIFY_NOT_REACHED();
+}
+
+InodeMetadata ProcFSProcessSubDirectoryInode::metadata() const
+{
+    MutexLocker locker(m_inode_lock);
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return {};
+    InodeMetadata metadata;
+    metadata.inode = { fsid(), process->component_index() };
+    metadata.mode = S_IFDIR | process->required_mode();
+    metadata.uid = process->owner_user();
+    metadata.gid = process->owner_group();
+    metadata.size = 0;
+    metadata.mtime = process->modified_time();
+    return metadata;
+}
+
+KResult ProcFSProcessSubDirectoryInode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
+{
+    MutexLocker locker(procfs().m_lock);
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return EINVAL;
+    switch (m_sub_directory_type) {
+    case SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions:
+        return process->traverse_file_descriptions_directory(procfs().fsid(), move(callback));
+    case SegmentedProcFSIndex::ProcessSubDirectory::Stacks:
+        return process->traverse_stacks_directory(procfs().fsid(), move(callback));
+    default:
+        VERIFY_NOT_REACHED();
+    }
+    VERIFY_NOT_REACHED();
+}
+
+RefPtr<Inode> ProcFSProcessSubDirectoryInode::lookup(StringView name)
+{
+    MutexLocker locker(procfs().m_lock);
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return {};
+    switch (m_sub_directory_type) {
+    case SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions:
+        return process->lookup_file_descriptions_directory(procfs(), name);
+    case SegmentedProcFSIndex::ProcessSubDirectory::Stacks:
+        return process->lookup_stacks_directory(procfs(), name);
+    default:
+        VERIFY_NOT_REACHED();
+    }
+    VERIFY_NOT_REACHED();
+}
+
+NonnullRefPtr<ProcFSProcessPropertyInode> ProcFSProcessPropertyInode::create_for_file_description_link(const ProcFS& procfs, unsigned file_description_index, ProcessID pid)
+{
+    return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessPropertyInode(procfs, file_description_index, pid)).release_nonnull();
+}
+NonnullRefPtr<ProcFSProcessPropertyInode> ProcFSProcessPropertyInode::create_for_thread_stack(const ProcFS& procfs, ThreadID stack_thread_index, ProcessID pid)
+{
+    return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessPropertyInode(procfs, stack_thread_index, pid)).release_nonnull();
+}
+NonnullRefPtr<ProcFSProcessPropertyInode> ProcFSProcessPropertyInode::create_for_pid_property(const ProcFS& procfs, SegmentedProcFSIndex::MainProcessProperty main_property_type, ProcessID pid)
+{
+    return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessPropertyInode(procfs, main_property_type, pid)).release_nonnull();
+}
+
+ProcFSProcessPropertyInode::ProcFSProcessPropertyInode(const ProcFS& procfs, SegmentedProcFSIndex::MainProcessProperty main_property_type, ProcessID pid)
+    : ProcFSProcessAssociatedInode(procfs, pid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid, main_property_type))
+    , m_parent_sub_directory_type(SegmentedProcFSIndex::ProcessSubDirectory::Reserved)
+{
+    m_possible_data.property_type = main_property_type;
+}
+
+ProcFSProcessPropertyInode::ProcFSProcessPropertyInode(const ProcFS& procfs, unsigned file_description_index, ProcessID pid)
+    : ProcFSProcessAssociatedInode(procfs, pid, SegmentedProcFSIndex::build_segmented_index_for_file_description(pid, file_description_index))
+    , m_parent_sub_directory_type(SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions)
+{
+    m_possible_data.property_index = file_description_index;
+}
+
+ProcFSProcessPropertyInode::ProcFSProcessPropertyInode(const ProcFS& procfs, ThreadID thread_stack_index, ProcessID pid)
+    : ProcFSProcessAssociatedInode(procfs, pid, SegmentedProcFSIndex::build_segmented_index_for_thread_stack(pid, thread_stack_index))
+    , m_parent_sub_directory_type(SegmentedProcFSIndex::ProcessSubDirectory::Stacks)
+{
+    m_possible_data.property_index = thread_stack_index.value();
+}
+
+KResult ProcFSProcessPropertyInode::attach(FileDescription& description)
+{
+    return refresh_data(description);
+}
+void ProcFSProcessPropertyInode::did_seek(FileDescription& description, off_t offset)
+{
+    if (offset != 0)
+        return;
+    (void)refresh_data(description);
+}
+
+static mode_t determine_procfs_process_inode_mode(SegmentedProcFSIndex::ProcessSubDirectory parent_sub_directory_type, SegmentedProcFSIndex::MainProcessProperty main_property)
+{
+    if (parent_sub_directory_type == SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions)
+        return S_IFLNK | 0400;
+    if (parent_sub_directory_type == SegmentedProcFSIndex::ProcessSubDirectory::Stacks)
+        return S_IFREG | 0400;
+    VERIFY(parent_sub_directory_type == SegmentedProcFSIndex::ProcessSubDirectory::Reserved);
+    if (main_property == SegmentedProcFSIndex::MainProcessProperty::BinaryLink)
+        return S_IFLNK | 0777;
+    if (main_property == SegmentedProcFSIndex::MainProcessProperty::CurrentWorkDirectoryLink)
+        return S_IFLNK | 0777;
+    if (main_property == SegmentedProcFSIndex::MainProcessProperty::RootLink)
+        return S_IFLNK | 0777;
+    return S_IFREG | 0400;
+}
+
+InodeMetadata ProcFSProcessPropertyInode::metadata() const
+{
+    MutexLocker locker(m_inode_lock);
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return {};
+    InodeMetadata metadata;
+    metadata.inode = { fsid(), process->component_index() };
+    metadata.mode = determine_procfs_process_inode_mode(m_parent_sub_directory_type, m_possible_data.property_type);
+    metadata.uid = process->owner_user();
+    metadata.gid = process->owner_group();
+    metadata.size = 0;
+    metadata.mtime = process->modified_time();
+    return metadata;
+}
+KResult ProcFSProcessPropertyInode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const
+{
+    VERIFY_NOT_REACHED();
+}
+KResultOr<size_t> ProcFSProcessPropertyInode::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, FileDescription* description) const
+{
+    dbgln_if(PROCFS_DEBUG, "ProcFS ProcessInformation: read_bytes offset: {} count: {}", offset, count);
+
+    VERIFY(offset >= 0);
+    VERIFY(buffer.user_or_kernel_ptr());
+
+    if (!description) {
+        KBufferBuilder builder;
+        auto process = Process::from_pid(associated_pid());
+        if (!process)
+            return KResult(ESRCH);
+        if (auto result = try_to_acquire_data(*process, builder); result.is_error())
+            return result.error();
+        auto data_buffer = builder.build();
+        if (!data_buffer)
+            return KResult(EFAULT);
+        ssize_t nread = min(static_cast<off_t>(data_buffer->size() - offset), static_cast<off_t>(count));
+        if (!buffer.write(data_buffer->data() + offset, nread))
+            return KResult(EFAULT);
+        return nread;
+    }
+    if (!description->data()) {
+        dbgln("ProcFS Process Information: Do not have cached data!");
+        return KResult(EIO);
+    }
+
+    MutexLocker locker(m_refresh_lock);
+
+    auto& typed_cached_data = static_cast<ProcFSInodeData&>(*description->data());
+    auto& data_buffer = typed_cached_data.buffer;
+
+    if (!data_buffer || (size_t)offset >= data_buffer->size())
+        return 0;
+
+    ssize_t nread = min(static_cast<off_t>(data_buffer->size() - offset), static_cast<off_t>(count));
+    if (!buffer.write(data_buffer->data() + offset, nread))
+        return KResult(EFAULT);
+
+    return nread;
+}
+RefPtr<Inode> ProcFSProcessPropertyInode::lookup(StringView)
+{
+    VERIFY_NOT_REACHED();
+}
+
+static KResult build_from_cached_data(KBufferBuilder& builder, ProcFSInodeData& cached_data)
+{
+    cached_data.buffer = builder.build();
+    if (!cached_data.buffer)
+        return ENOMEM;
+    return KSuccess;
+}
+
+KResult ProcFSProcessPropertyInode::try_to_acquire_data(Process& process, KBufferBuilder& builder) const
+{
+    // FIXME: Verify process is already ref-counted
+    if (m_parent_sub_directory_type == SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions) {
+        if (auto result = process.procfs_get_file_description_link(m_possible_data.property_index, builder); result.is_error())
+            return result.error();
+        return KSuccess;
+    }
+    if (m_parent_sub_directory_type == SegmentedProcFSIndex::ProcessSubDirectory::Stacks) {
+        if (auto result = process.procfs_get_thread_stack(m_possible_data.property_index, builder); result.is_error())
+            return result.error();
+        return KSuccess;
+    }
+
+    VERIFY(m_parent_sub_directory_type == SegmentedProcFSIndex::ProcessSubDirectory::Reserved);
+    switch (m_possible_data.property_type) {
+    case SegmentedProcFSIndex::MainProcessProperty::Unveil:
+        return process.procfs_get_fds_stats(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::Pledge:
+        return process.procfs_get_pledge_stats(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::FileDescriptions:
+        return process.procfs_get_fds_stats(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::BinaryLink:
+        return process.procfs_get_binary_link(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::CurrentWorkDirectoryLink:
+        return process.procfs_get_current_work_directory_link(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::PerformanceEvents:
+        return process.procfs_get_perf_events(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::VirtualMemoryStats:
+        return process.procfs_get_virtual_memory_stats(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::RootLink:
+        return process.procfs_get_root_link(builder);
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+KResult ProcFSProcessPropertyInode::refresh_data(FileDescription& description)
+{
+    // For process-specific inodes, hold the process's ptrace lock across refresh
+    // and refuse to load data if the process is not dumpable.
+    // Without this, files opened before a process went non-dumpable could still be used for dumping.
+    auto process = Process::from_pid(associated_pid());
+    if (!process)
+        return KResult(ESRCH);
+    process->ptrace_lock().lock();
+    if (!process->is_dumpable()) {
+        process->ptrace_lock().unlock();
+        return EPERM;
+    }
+    ScopeGuard guard = [&] {
+        process->ptrace_lock().unlock();
+    };
+    MutexLocker locker(m_refresh_lock);
+    auto& cached_data = description.data();
+    if (!cached_data) {
+        cached_data = adopt_own_if_nonnull(new (nothrow) ProcFSInodeData);
+        if (!cached_data)
+            return ENOMEM;
+    }
+    KBufferBuilder builder;
+    if (auto result = try_to_acquire_data(*process, builder); result.is_error())
+        return result;
+    return build_from_cached_data(builder, static_cast<ProcFSInodeData&>(*cached_data));
+}
 }

Kernel/FileSystem/ProcFS.h

@@ -14,12 +14,17 @@
 #include <Kernel/KBufferBuilder.h>
 #include <Kernel/Locking/Mutex.h>
 #include <Kernel/ProcessExposed.h>
+#include <Kernel/UnixTypes.h>
 
 namespace Kernel {
 
 class ProcFS final : public FileSystem {
     friend class ProcFSInode;
     friend class ProcFSDirectoryInode;
+    friend class ProcFSProcessDirectoryInode;
+    friend class ProcFSGlobalInode;
+    friend class ProcFSAssociatedProcessInode;
+    friend class ProcFSProcessSubDirectoryInode;
 
 public:
     virtual ~ProcFS() override;
@@ -40,33 +45,50 @@ class ProcFSInode : public Inode {
     friend class ProcFS;
 
 public:
-    static NonnullRefPtr<ProcFSInode> create(const ProcFS&, const ProcFSExposedComponent&);
     virtual ~ProcFSInode() override;
+
+protected:
+    ProcFSInode(const ProcFS&, InodeIndex);
+
+    ProcFS& procfs() { return static_cast<ProcFS&>(Inode::fs()); }
+    ProcFS const& procfs() const { return static_cast<ProcFS const&>(Inode::fs()); }
+
+    // ^Inode
+    virtual KResult attach(FileDescription& description) = 0;
+    virtual void did_seek(FileDescription&, off_t) = 0;
+    virtual void flush_metadata() override final;
+    virtual KResultOr<NonnullRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, uid_t, gid_t) override final;
+    virtual KResult add_child(Inode&, const StringView& name, mode_t) override final;
+    virtual KResult remove_child(const StringView& name) override final;
+    virtual KResult chmod(mode_t) override final;
+    virtual KResult chown(uid_t, gid_t) override final;
+    virtual KResult truncate(u64) override final;
+};
+
+class ProcFSGlobalInode : public ProcFSInode {
+    friend class ProcFS;
+
+public:
+    static NonnullRefPtr<ProcFSGlobalInode> create(const ProcFS&, const ProcFSExposedComponent&);
+    virtual ~ProcFSGlobalInode() override {};
     StringView name() const;
 
 protected:
-    ProcFSInode(const ProcFS&, const ProcFSExposedComponent&);
+    ProcFSGlobalInode(const ProcFS&, const ProcFSExposedComponent&);
 
     // ^Inode
-    virtual KResult attach(FileDescription& description) override;
+    virtual KResult attach(FileDescription& description) override final;
-    virtual KResultOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer& buffer, FileDescription*) const override;
+    virtual KResultOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer& buffer, FileDescription*) const override final;
-    virtual KResult traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
+    virtual KResultOr<size_t> write_bytes(off_t, size_t, const UserOrKernelBuffer& buffer, FileDescription*) override final;
-    virtual RefPtr<Inode> lookup(StringView name) override;
+    virtual void did_seek(FileDescription&, off_t) override final;
-    virtual void flush_metadata() override;
     virtual InodeMetadata metadata() const override;
-    virtual KResultOr<size_t> write_bytes(off_t, size_t, const UserOrKernelBuffer& buffer, FileDescription*) override;
+    virtual KResult traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
-    virtual KResultOr<NonnullRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, uid_t, gid_t) override;
+    virtual RefPtr<Inode> lookup(StringView) override;
-    virtual KResult add_child(Inode&, const StringView& name, mode_t) override;
-    virtual KResult remove_child(const StringView& name) override;
-    virtual void did_seek(FileDescription&, off_t) override;
-    virtual KResult chmod(mode_t) override;
-    virtual KResult chown(uid_t, gid_t) override;
-    virtual KResult truncate(u64) override;
 
     NonnullRefPtr<ProcFSExposedComponent> m_associated_component;
 };
 
-class ProcFSLinkInode : public ProcFSInode {
+class ProcFSLinkInode : public ProcFSGlobalInode {
     friend class ProcFS;
 
 public:
@@ -77,16 +99,13 @@ protected:
     virtual InodeMetadata metadata() const override;
 };
 
-class ProcFSDirectoryInode : public ProcFSInode {
+class ProcFSDirectoryInode final : public ProcFSGlobalInode {
     friend class ProcFS;
 
 public:
     static NonnullRefPtr<ProcFSDirectoryInode> create(const ProcFS&, const ProcFSExposedComponent&);
     virtual ~ProcFSDirectoryInode() override;
 
-    ProcFS& fs() { return static_cast<ProcFS&>(Inode::fs()); }
-    ProcFS const& fs() const { return static_cast<ProcFS const&>(Inode::fs()); }
-
 protected:
     ProcFSDirectoryInode(const ProcFS&, const ProcFSExposedComponent&);
     // ^Inode
@@ -95,4 +114,84 @@ protected:
     virtual RefPtr<Inode> lookup(StringView name) override;
 };
 
+class ProcFSProcessAssociatedInode : public ProcFSInode {
+    friend class ProcFS;
+
+protected:
+    ProcFSProcessAssociatedInode(const ProcFS&, ProcessID, InodeIndex);
+    ProcessID associated_pid() const { return m_pid; }
+
+    // ^Inode
+    virtual KResultOr<size_t> write_bytes(off_t, size_t, const UserOrKernelBuffer& buffer, FileDescription*) override final;
+
+private:
+    const ProcessID m_pid;
+};
+
+class ProcFSProcessDirectoryInode final : public ProcFSProcessAssociatedInode {
+    friend class ProcFS;
+
+public:
+    static NonnullRefPtr<ProcFSProcessDirectoryInode> create(const ProcFS&, ProcessID);
+
+private:
+    ProcFSProcessDirectoryInode(const ProcFS&, ProcessID);
+    // ^Inode
+    virtual KResult attach(FileDescription& description) override;
+    virtual void did_seek(FileDescription&, off_t) override { }
+    virtual InodeMetadata metadata() const override;
+    virtual KResult traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
+    virtual KResultOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer& buffer, FileDescription*) const override final;
+    virtual RefPtr<Inode> lookup(StringView name) override;
+};
+
+class ProcFSProcessSubDirectoryInode final : public ProcFSProcessAssociatedInode {
+    friend class ProcFS;
+
+public:
+    static NonnullRefPtr<ProcFSProcessSubDirectoryInode> create(const ProcFS&, SegmentedProcFSIndex::ProcessSubDirectory, ProcessID);
+
+private:
+    ProcFSProcessSubDirectoryInode(const ProcFS&, SegmentedProcFSIndex::ProcessSubDirectory, ProcessID);
+    // ^Inode
+    virtual KResult attach(FileDescription& description) override;
+    virtual void did_seek(FileDescription&, off_t) override;
+    virtual InodeMetadata metadata() const override;
+    virtual KResult traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
+    virtual KResultOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer& buffer, FileDescription*) const override final;
+    virtual RefPtr<Inode> lookup(StringView name) override;
+
+    const SegmentedProcFSIndex::ProcessSubDirectory m_sub_directory_type;
+};
+
+class ProcFSProcessPropertyInode final : public ProcFSProcessAssociatedInode {
+    friend class ProcFS;
+
+public:
+    static NonnullRefPtr<ProcFSProcessPropertyInode> create_for_file_description_link(const ProcFS&, unsigned, ProcessID);
+    static NonnullRefPtr<ProcFSProcessPropertyInode> create_for_thread_stack(const ProcFS&, ThreadID, ProcessID);
+    static NonnullRefPtr<ProcFSProcessPropertyInode> create_for_pid_property(const ProcFS&, SegmentedProcFSIndex::MainProcessProperty, ProcessID);
+
+private:
+    ProcFSProcessPropertyInode(const ProcFS&, SegmentedProcFSIndex::MainProcessProperty, ProcessID);
+    ProcFSProcessPropertyInode(const ProcFS&, ThreadID, ProcessID);
+    ProcFSProcessPropertyInode(const ProcFS&, unsigned, ProcessID);
+    // ^Inode
+    virtual KResult attach(FileDescription& description) override;
+    virtual void did_seek(FileDescription&, off_t) override;
+    virtual InodeMetadata metadata() const override;
+    virtual KResult traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
+    virtual KResultOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer& buffer, FileDescription*) const override final;
+    virtual RefPtr<Inode> lookup(StringView name) override final;
+
+    KResult refresh_data(FileDescription& description);
+    KResult try_to_acquire_data(Process& process, KBufferBuilder& builder) const;
+
+    const SegmentedProcFSIndex::ProcessSubDirectory m_parent_sub_directory_type;
+    union {
+        SegmentedProcFSIndex::MainProcessProperty property_type;
+        unsigned property_index;
+    } m_possible_data;
+    mutable Mutex m_refresh_lock;
+};
 }

Kernel/GlobalProcessExposed.cpp

@@ -27,6 +27,7 @@
 #include <Kernel/Net/Routing.h>
 #include <Kernel/Net/TCPSocket.h>
 #include <Kernel/Net/UDPSocket.h>
+#include <Kernel/Process.h>
 #include <Kernel/ProcessExposed.h>
 #include <Kernel/Sections.h>
 #include <Kernel/TTY/TTY.h>
@@ -905,10 +906,13 @@ KResult ProcFSRootDirectory::traverse_as_directory(unsigned fsid, Function<bool(
         InodeIdentifier identifier = { fsid, component.component_index() };
         callback({ component.name(), identifier, 0 });
     }
-    for (auto& component : m_process_directories) {
+    processes().for_each_shared([&](Process& process) {
-        InodeIdentifier identifier = { fsid, component.component_index() };
+        VERIFY(!(process.pid() < 0));
-        callback({ component.name(), identifier, 0 });
+        u64 process_id = (u64)process.pid().value();
-    }
+        InodeIdentifier identifier = { fsid, static_cast<InodeIndex>(process_id << 36) };
+        callback({ String::formatted("{:d}", process.pid().value()), identifier, 0 });
+        return IterationDecision::Continue;
+    });
     return KSuccess;
 }
 
@@ -917,12 +921,12 @@ RefPtr<ProcFSExposedComponent> ProcFSRootDirectory::lookup(StringView name)
     if (auto candidate = ProcFSExposedDirectory::lookup(name); !candidate.is_null())
         return candidate;
 
-    for (auto& component : m_process_directories) {
+    String process_directory_name = name;
-        if (component.name() == name) {
+    auto pid = process_directory_name.to_uint<unsigned>();
-            return component;
+    if (!pid.has_value())
-        }
+        return {};
-    }
+    auto actual_pid = pid.value();
-    return {};
+    return Process::from_pid(actual_pid);
 }
 
 UNMAP_AFTER_INIT ProcFSRootDirectory::ProcFSRootDirectory()
@@ -934,14 +938,4 @@ UNMAP_AFTER_INIT ProcFSRootDirectory::~ProcFSRootDirectory()
 {
 }
 
-RefPtr<ProcFSProcessDirectory> ProcFSRootDirectory::process_directory_for(Process& process)
-{
-    RefPtr<Process> checked_process = process;
-    for (auto& directory : m_process_directories) {
-        if (directory.associated_process().ptr() == checked_process.ptr())
-            return directory;
-    }
-    return {};
-}
-
 }

Kernel/Process.cpp

@@ -141,7 +141,6 @@ void Process::register_new(Process& process)
     processes().with_exclusive([&](auto& list) {
         list.prepend(process);
     });
-    ProcFSComponentRegistry::the().register_new_process(process);
 }
 
 RefPtr<Process> Process::create_user_process(RefPtr<Thread>& first_thread, const String& path, uid_t uid, gid_t gid, ProcessID parent_pid, int& error, Vector<String>&& arguments, Vector<String>&& environment, TTY* tty)
@@ -594,12 +593,6 @@ void Process::finalize()
     m_arguments.clear();
     m_environment.clear();
 
-    // Note: We need to remove the references from the ProcFS registrar
-    // If we don't do it here, we can't drop the object later, and we can't
-    // do this from the destructor because the state of the object doesn't
-    // allow us to take references anymore.
-    ProcFSComponentRegistry::the().unregister_process(*this);
-
     m_state.store(State::Dead, AK::MemoryOrder::memory_order_release);
 
     {
@@ -752,13 +745,6 @@ void Process::FileDescriptionAndFlags::clear()
     // FIXME: Verify Process::m_fds_lock is locked!
     m_description = nullptr;
     m_flags = 0;
-    m_global_procfs_inode_index = 0;
-}
-
-void Process::FileDescriptionAndFlags::refresh_inode_index()
-{
-    // FIXME: Verify Process::m_fds_lock is locked!
-    m_global_procfs_inode_index = ProcFSComponentRegistry::the().allocate_inode_index();
 }
 
 void Process::FileDescriptionAndFlags::set(NonnullRefPtr<FileDescription>&& description, u32 flags)
@@ -766,7 +752,6 @@ void Process::FileDescriptionAndFlags::set(NonnullRefPtr<FileDescription>&& desc
     // FIXME: Verify Process::m_fds_lock is locked!
     m_description = move(description);
     m_flags = flags;
-    m_global_procfs_inode_index = ProcFSComponentRegistry::the().allocate_inode_index();
 }
 
 Custody& Process::root_directory()

Kernel/Process.h

@@ -27,6 +27,7 @@
 #include <Kernel/Locking/ProtectedValue.h>
 #include <Kernel/Memory/AddressSpace.h>
 #include <Kernel/PerformanceEventBuffer.h>
+#include <Kernel/ProcessExposed.h>
 #include <Kernel/ProcessGroup.h>
 #include <Kernel/StdLib.h>
 #include <Kernel/Thread.h>
@@ -84,7 +85,7 @@ typedef HashMap<FlatPtr, RefPtr<FutexQueue>> FutexQueues;
 struct LoadResult;
 
 class Process
-    : public RefCounted<Process>
+    : public ProcFSExposedComponent
     , public Weakable<Process> {
 
 private:
@@ -551,6 +552,31 @@ private:
 
     void setup_socket_fd(int fd, NonnullRefPtr<FileDescription> description, int type);
 
+public:
+    // ^ProcFSExposedComponent stats
+    virtual InodeIndex component_index() const override;
+    virtual NonnullRefPtr<Inode> to_inode(const ProcFS& procfs_instance) const override;
+    virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
+    virtual mode_t required_mode() const override { return 0555; }
+    virtual uid_t owner_user() const override { return uid(); }
+    virtual gid_t owner_group() const override { return gid(); }
+    KResult procfs_get_fds_stats(KBufferBuilder& builder) const;
+    KResult procfs_get_perf_events(KBufferBuilder& builder) const;
+    KResult procfs_get_unveil_stats(KBufferBuilder& builder) const;
+    KResult procfs_get_pledge_stats(KBufferBuilder& builder) const;
+    KResult procfs_get_virtual_memory_stats(KBufferBuilder& builder) const;
+    KResult procfs_get_binary_link(KBufferBuilder& builder) const;
+    KResult procfs_get_root_link(KBufferBuilder& builder) const;
+    KResult procfs_get_current_work_directory_link(KBufferBuilder& builder) const;
+    mode_t binary_link_required_mode() const;
+    KResultOr<size_t> procfs_get_thread_stack(ThreadID thread_id, KBufferBuilder& builder) const;
+    KResult traverse_stacks_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const;
+    RefPtr<Inode> lookup_stacks_directory(const ProcFS&, StringView name) const;
+    KResultOr<size_t> procfs_get_file_description_link(unsigned fd, KBufferBuilder& builder) const;
+    KResult traverse_file_descriptions_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const;
+    RefPtr<Inode> lookup_file_descriptions_directory(const ProcFS&, StringView name) const;
+
+private:
     inline PerformanceEventBuffer* current_perf_events_buffer()
     {
         if (g_profiling_all_threads)
@@ -595,22 +621,16 @@ public:
 
         FileDescription* description() { return m_description; }
         const FileDescription* description() const { return m_description; }
-        InodeIndex global_procfs_inode_index() const { return m_global_procfs_inode_index; }
         u32 flags() const { return m_flags; }
         void set_flags(u32 flags) { m_flags = flags; }
 
         void clear();
         void set(NonnullRefPtr<FileDescription>&&, u32 flags = 0);
-        void refresh_inode_index();
 
     private:
         RefPtr<FileDescription> m_description;
         bool m_is_allocated { false };
         u32 m_flags { 0 };
-
-        // Note: This is needed so when we generate inodes for ProcFS, we know that
-        // we assigned a global Inode index to it so we can use it later
-        InodeIndex m_global_procfs_inode_index;
     };
 
     class ScopedDescriptionAllocation;
@@ -626,9 +646,6 @@ public:
             ScopedSpinLock lock(m_fds_lock);
             ScopedSpinLock lock_other(other.m_fds_lock);
             m_fds_metadatas = other.m_fds_metadatas;
-            for (auto& file_description_metadata : m_fds_metadatas) {
-                file_description_metadata.refresh_inode_index();
-            }
             return *this;
         }
 

Kernel/ProcessExposed.cpp

@@ -18,35 +18,77 @@ namespace Kernel {
 static SpinLock<u8> s_index_lock;
 static InodeIndex s_next_inode_index = 0;
 
-static size_t s_allocate_inode_index()
+namespace SegmentedProcFSIndex {
+static InodeIndex __build_raw_segmented_index(u32 primary, u16 sub_directory, u32 property)
+{
+    VERIFY(primary < 0x10000000);
+    VERIFY(property < 0x100000);
+    // Note: The sub-directory part is already limited to 0xFFFF, so no need to VERIFY it.
+    return static_cast<u64>((static_cast<u64>(primary) << 36) | (static_cast<u64>(sub_directory) << 20) | property);
+}
+
+static InodeIndex build_segmented_index_with_known_pid(ProcessID pid, u16 sub_directory, u32 property)
+{
+    return __build_raw_segmented_index(pid.value() + 1, sub_directory, property);
+}
+
+static InodeIndex build_segmented_index_with_unknown_property(ProcessID pid, ProcessSubDirectory sub_directory, unsigned property)
+{
+    return build_segmented_index_with_known_pid(pid, to_underlying(sub_directory), static_cast<u32>(property));
+}
+
+InodeIndex build_segmented_index_for_pid_directory(ProcessID pid)
+{
+    return build_segmented_index_with_unknown_property(pid, ProcessSubDirectory::Reserved, to_underlying(MainProcessProperty::Reserved));
+}
+
+InodeIndex build_segmented_index_for_sub_directory(ProcessID pid, ProcessSubDirectory sub_directory)
+{
+    return build_segmented_index_with_unknown_property(pid, sub_directory, to_underlying(MainProcessProperty::Reserved));
+}
+
+InodeIndex build_segmented_index_for_main_property(ProcessID pid, ProcessSubDirectory sub_directory, MainProcessProperty property)
+{
+    return build_segmented_index_with_known_pid(pid, to_underlying(sub_directory), to_underlying(property));
+}
+
+InodeIndex build_segmented_index_for_main_property_in_pid_directory(ProcessID pid, MainProcessProperty property)
+{
+    return build_segmented_index_with_known_pid(pid, to_underlying(ProcessSubDirectory::Reserved), to_underlying(property));
+}
+
+InodeIndex build_segmented_index_for_thread_stack(ProcessID pid, ThreadID thread_id)
+{
+    return build_segmented_index_with_unknown_property(pid, ProcessSubDirectory::Stacks, thread_id.value());
+}
+
+InodeIndex build_segmented_index_for_file_description(ProcessID pid, unsigned fd)
+{
+    return build_segmented_index_with_unknown_property(pid, ProcessSubDirectory::FileDescriptions, fd);
+}
+
+}
+
+static size_t s_allocate_global_inode_index()
 {
     ScopedSpinLock lock(s_index_lock);
     s_next_inode_index = s_next_inode_index.value() + 1;
+    // Note: Global ProcFS indices must be above 0 and up to maximum of what 36 bit (2 ^ 36 - 1) can represent.
     VERIFY(s_next_inode_index > 0);
+    VERIFY(s_next_inode_index < 0x100000000);
     return s_next_inode_index.value();
 }
 
-InodeIndex ProcFSComponentRegistry::allocate_inode_index() const
+ProcFSExposedComponent::ProcFSExposedComponent()
 {
-    return s_allocate_inode_index();
 }
 
 ProcFSExposedComponent::ProcFSExposedComponent(StringView name)
-    : m_component_index(s_allocate_inode_index())
+    : m_component_index(s_allocate_global_inode_index())
 {
     m_name = KString::try_create(name);
 }
 
-// Note: This constructor is intended to be used in /proc/pid/fd/* symlinks
-// so we preallocated inode index for them so we just need to set it here.
-ProcFSExposedComponent::ProcFSExposedComponent(StringView name, InodeIndex preallocated_index)
-    : m_component_index(preallocated_index.value())
-{
-    VERIFY(preallocated_index.value() != 0);
-    VERIFY(preallocated_index <= s_next_inode_index);
-    m_name = KString::try_create(name);
-}
-
 ProcFSExposedDirectory::ProcFSExposedDirectory(StringView name)
     : ProcFSExposedComponent(name)
 {
@@ -62,16 +104,6 @@ ProcFSExposedLink::ProcFSExposedLink(StringView name)
     : ProcFSExposedComponent(name)
 {
 }
-
-ProcFSExposedLink::ProcFSExposedLink(StringView name, InodeIndex preallocated_index)
-    : ProcFSExposedComponent(name, preallocated_index)
-{
-}
-
-struct ProcFSInodeData : public FileDescriptionData {
-    OwnPtr<KBuffer> buffer;
-};
-
 KResultOr<size_t> ProcFSGlobalInformation::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, FileDescription* description) const
 {
     dbgln_if(PROCFS_DEBUG, "ProcFSGlobalInformation @ {}: read_bytes offset: {} count: {}", name(), offset, count);
@@ -121,71 +153,6 @@ KResult ProcFSGlobalInformation::refresh_data(FileDescription& description) cons
     return KSuccess;
 }
 
-KResultOr<size_t> ProcFSProcessInformation::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, FileDescription* description) const
-{
-    dbgln_if(PROCFS_DEBUG, "ProcFSProcessInformation @ {}: read_bytes offset: {} count: {}", name(), offset, count);
-
-    VERIFY(offset >= 0);
-    VERIFY(buffer.user_or_kernel_ptr());
-
-    if (!description)
-        return KResult(EIO);
-    if (!description->data()) {
-        dbgln("ProcFSGlobalInformation: Do not have cached data!");
-        return KResult(EIO);
-    }
-
-    MutexLocker locker(m_refresh_lock);
-
-    auto& typed_cached_data = static_cast<ProcFSInodeData&>(*description->data());
-    auto& data_buffer = typed_cached_data.buffer;
-
-    if (!data_buffer || (size_t)offset >= data_buffer->size())
-        return 0;
-
-    ssize_t nread = min(static_cast<off_t>(data_buffer->size() - offset), static_cast<off_t>(count));
-    if (!buffer.write(data_buffer->data() + offset, nread))
-        return KResult(EFAULT);
-
-    return nread;
-}
-
-KResult ProcFSProcessInformation::refresh_data(FileDescription& description) const
-{
-    // For process-specific inodes, hold the process's ptrace lock across refresh
-    // and refuse to load data if the process is not dumpable.
-    // Without this, files opened before a process went non-dumpable could still be used for dumping.
-    auto parent_directory = const_cast<ProcFSProcessInformation&>(*this).m_parent_directory.strong_ref();
-    if (parent_directory.is_null())
-        return KResult(EINVAL);
-    auto process = parent_directory->associated_process();
-    if (!process)
-        return KResult(ESRCH);
-    process->ptrace_lock().lock();
-    if (!process->is_dumpable()) {
-        process->ptrace_lock().unlock();
-        return EPERM;
-    }
-    ScopeGuard guard = [&] {
-        process->ptrace_lock().unlock();
-    };
-    MutexLocker locker(m_refresh_lock);
-    auto& cached_data = description.data();
-    if (!cached_data) {
-        cached_data = adopt_own_if_nonnull(new (nothrow) ProcFSInodeData);
-        if (!cached_data)
-            return ENOMEM;
-    }
-    KBufferBuilder builder;
-    if (!const_cast<ProcFSProcessInformation&>(*this).output(builder))
-        return ENOENT;
-    auto& typed_cached_data = static_cast<ProcFSInodeData&>(*cached_data);
-    typed_cached_data.buffer = builder.build();
-    if (!typed_cached_data.buffer)
-        return ENOMEM;
-    return KSuccess;
-}
-
 KResultOr<size_t> ProcFSExposedLink::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, FileDescription*) const
 {
     VERIFY(offset == 0);
@@ -210,7 +177,7 @@ NonnullRefPtr<Inode> ProcFSExposedLink::to_inode(const ProcFS& procfs_instance)
 
 NonnullRefPtr<Inode> ProcFSExposedComponent::to_inode(const ProcFS& procfs_instance) const
 {
-    return ProcFSInode::create(procfs_instance, *this);
+    return ProcFSGlobalInode::create(procfs_instance, *this);
 }
 
 NonnullRefPtr<Inode> ProcFSExposedDirectory::to_inode(const ProcFS& procfs_instance) const

Kernel/ProcessExposed.h

@@ -13,27 +13,49 @@
 #include <AK/Types.h>
 #include <Kernel/Arch/x86/CPU.h>
 #include <Kernel/FileSystem/File.h>
+#include <Kernel/FileSystem/FileDescription.h>
 #include <Kernel/FileSystem/FileSystem.h>
 #include <Kernel/KBufferBuilder.h>
 #include <Kernel/KResult.h>
-#include <Kernel/Process.h>
 #include <Kernel/UserOrKernelBuffer.h>
 
 namespace Kernel {
 
+namespace SegmentedProcFSIndex {
+enum class MainProcessProperty {
+    Reserved = 0,
+    Unveil = 1,
+    Pledge = 2,
+    FileDescriptions = 3,
+    BinaryLink = 4,
+    CurrentWorkDirectoryLink = 5,
+    PerformanceEvents = 6,
+    VirtualMemoryStats = 7,
+    RootLink = 8,
+};
+
+enum class ProcessSubDirectory {
+    Reserved = 0,
+    FileDescriptions = 1,
+    Stacks = 2,
+};
+
+void read_segments(u32& primary, ProcessSubDirectory& sub_directory, MainProcessProperty& property);
+InodeIndex build_segmented_index_for_pid_directory(ProcessID);
+InodeIndex build_segmented_index_for_sub_directory(ProcessID, ProcessSubDirectory sub_directory);
+InodeIndex build_segmented_index_for_main_property(ProcessID, ProcessSubDirectory sub_directory, MainProcessProperty property);
+InodeIndex build_segmented_index_for_main_property_in_pid_directory(ProcessID, MainProcessProperty property);
+InodeIndex build_segmented_index_for_thread_stack(ProcessID, ThreadID);
+InodeIndex build_segmented_index_for_file_description(ProcessID, unsigned);
+}
+
 class ProcFSComponentRegistry {
 public:
     static ProcFSComponentRegistry& the();
 
     static void initialize();
-
-    InodeIndex allocate_inode_index() const;
-
     ProcFSComponentRegistry();
 
-    void register_new_process(Process&);
-    void unregister_process(Process&);
-
     ProcFSRootDirectory& root_directory() { return *m_root_directory; }
     Mutex& get_lock() { return m_lock; }
 
@@ -64,13 +86,13 @@ public:
 
     virtual NonnullRefPtr<Inode> to_inode(const ProcFS& procfs_instance) const;
 
-    InodeIndex component_index() const { return m_component_index; };
+    virtual InodeIndex component_index() const { return m_component_index; }
 
     virtual ~ProcFSExposedComponent() = default;
 
 protected:
+    ProcFSExposedComponent();
     explicit ProcFSExposedComponent(StringView name);
-    ProcFSExposedComponent(StringView name, InodeIndex preallocated_index);
 
 private:
     OwnPtr<KString> m_name;
@@ -80,7 +102,6 @@ private:
 class ProcFSExposedDirectory
     : public ProcFSExposedComponent
     , public Weakable<ProcFSExposedDirectory> {
-    friend class ProcFSProcessDirectory;
     friend class ProcFSComponentRegistry;
 
 public:
@@ -114,62 +135,24 @@ public:
 protected:
     virtual bool acquire_link(KBufferBuilder& builder) = 0;
     explicit ProcFSExposedLink(StringView name);
-    ProcFSExposedLink(StringView name, InodeIndex preallocated_index);
     mutable Mutex m_lock { "ProcFSLink" };
 };
 
-class ProcFSProcessDirectory final
-    : public ProcFSExposedDirectory {
-    friend class ProcFSComponentRegistry;
-    friend class ProcFSRootDirectory;
-    friend class ProcFSProcessInformation;
-    friend class ProcFSProcessPledge;
-    friend class ProcFSProcessUnveil;
-    friend class ProcFSProcessPerformanceEvents;
-    friend class ProcFSProcessFileDescription;
-    friend class ProcFSProcessFileDescriptions;
-    friend class ProcFSProcessOverallFileDescriptions;
-    friend class ProcFSProcessRoot;
-    friend class ProcFSProcessVirtualMemory;
-    friend class ProcFSProcessCurrentWorkDirectory;
-    friend class ProcFSProcessBinary;
-    friend class ProcFSProcessStacks;
-
-public:
-    static NonnullRefPtr<ProcFSProcessDirectory> create(const Process&);
-    RefPtr<Process> associated_process() { return m_associated_process; }
-
-    virtual uid_t owner_user() const override { return m_associated_process ? m_associated_process->uid() : 0; }
-    virtual gid_t owner_group() const override { return m_associated_process ? m_associated_process->gid() : 0; }
-    virtual KResult refresh_data(FileDescription&) const override;
-    virtual RefPtr<ProcFSExposedComponent> lookup(StringView name) override;
-    virtual mode_t required_mode() const override { return 0500; }
-
-    virtual void prepare_for_deletion() override;
-
-private:
-    void on_attach();
-    IntrusiveListNode<ProcFSProcessDirectory, RefPtr<ProcFSProcessDirectory>> m_list_node;
-
-    explicit ProcFSProcessDirectory(const Process&);
-    RefPtr<Process> m_associated_process;
-};
-
 class ProcFSRootDirectory final : public ProcFSExposedDirectory {
     friend class ProcFSComponentRegistry;
 
 public:
     virtual RefPtr<ProcFSExposedComponent> lookup(StringView name) override;
-
-    RefPtr<ProcFSProcessDirectory> process_directory_for(Process&);
     static NonnullRefPtr<ProcFSRootDirectory> must_create();
     virtual ~ProcFSRootDirectory();
 
 private:
     virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
     ProcFSRootDirectory();
+};
 
-    IntrusiveList<ProcFSProcessDirectory, RefPtr<ProcFSProcessDirectory>, &ProcFSProcessDirectory::m_list_node> m_process_directories;
+struct ProcFSInodeData : public FileDescriptionData {
+    OwnPtr<KBuffer> buffer;
 };
 
 class ProcFSGlobalInformation : public ProcFSExposedComponent {
@@ -208,47 +191,4 @@ protected:
     }
 };
 
-class ProcFSProcessInformation : public ProcFSExposedComponent {
-public:
-    virtual ~ProcFSProcessInformation() override {};
-
-    virtual KResultOr<size_t> read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, FileDescription* description) const override;
-
-    virtual uid_t owner_user() const override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (!parent_directory)
-            return false;
-        auto process = parent_directory->associated_process();
-        if (!process)
-            return false;
-        return process->uid();
-    }
-    virtual gid_t owner_group() const override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (!parent_directory)
-            return false;
-        auto process = parent_directory->associated_process();
-        if (!process)
-            return false;
-        return process->gid();
-    }
-
-    virtual mode_t required_mode() const override { return 0400; }
-
-protected:
-    ProcFSProcessInformation(StringView name, const ProcFSProcessDirectory& process_directory)
-        : ProcFSExposedComponent(name)
-        , m_parent_directory(process_directory)
-    {
-    }
-
-    virtual KResult refresh_data(FileDescription&) const override;
-    virtual bool output(KBufferBuilder& builder) = 0;
-
-    WeakPtr<ProcFSProcessDirectory> m_parent_directory;
-    mutable Mutex m_refresh_lock;
-};
-
 }

Kernel/ProcessSpecificExposed.cpp

@@ -9,601 +9,294 @@
 #include <AK/JsonValue.h>
 #include <Kernel/Arch/x86/InterruptDisabler.h>
 #include <Kernel/FileSystem/Custody.h>
+#include <Kernel/FileSystem/ProcFS.h>
 #include <Kernel/KBufferBuilder.h>
 #include <Kernel/Memory/AnonymousVMObject.h>
 #include <Kernel/Memory/MemoryManager.h>
+#include <Kernel/Process.h>
 #include <Kernel/ProcessExposed.h>
 
 namespace Kernel {
 
-class ProcFSProcessStacks;
+KResultOr<size_t> Process::procfs_get_thread_stack(ThreadID thread_id, KBufferBuilder& builder) const
-class ProcFSThreadStack final : public ProcFSProcessInformation {
-public:
-    // Note: We pass const ProcFSProcessStacks& to enforce creation with this type of directory
-    static NonnullRefPtr<ProcFSThreadStack> create(const ProcFSProcessDirectory& process_directory, const ProcFSProcessStacks&, const Thread& thread)
-    {
-        return adopt_ref(*new (nothrow) ProcFSThreadStack(process_directory, thread));
-    }
-
-private:
-    explicit ProcFSThreadStack(const ProcFSProcessDirectory& process_directory, const Thread& thread)
-        : ProcFSProcessInformation(String::formatted("{}", thread.tid()), process_directory)
-        , m_associated_thread(thread)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        JsonArraySerializer array { builder };
-        bool show_kernel_addresses = Process::current()->is_superuser();
-        bool kernel_address_added = false;
-        for (auto address : Processor::capture_stack_trace(*m_associated_thread, 1024)) {
-            if (!show_kernel_addresses && !Memory::is_user_address(VirtualAddress { address })) {
-                if (kernel_address_added)
-                    continue;
-                address = 0xdeadc0de;
-                kernel_address_added = true;
-            }
-            array.add(address);
-        }
-
-        array.finish();
-        return true;
-    }
-
-    NonnullRefPtr<Thread> m_associated_thread;
-};
-
-class ProcFSProcessStacks final : public ProcFSExposedDirectory {
-    // Note: This directory is special, because everything that is created here is dynamic!
-    // This means we don't register anything in the m_components Vector, and every inode
-    // is created in runtime when called to get it
-    // Every ProcFSThreadStack (that represents a thread stack) is created only as a temporary object
-    // therefore, we don't use m_components so when we are done with the ProcFSThreadStack object,
-    // It should be deleted (as soon as possible)
-public:
-    virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
-    virtual RefPtr<ProcFSExposedComponent> lookup(StringView name) override;
-
-    static NonnullRefPtr<ProcFSProcessStacks> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        auto directory = adopt_ref(*new (nothrow) ProcFSProcessStacks(parent_directory));
-        return directory;
-    }
-
-    virtual void prepare_for_deletion() override
-    {
-        ProcFSExposedDirectory::prepare_for_deletion();
-        m_process_directory.clear();
-    }
-
-private:
-    ProcFSProcessStacks(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedDirectory("stacks"sv, parent_directory)
-        , m_process_directory(parent_directory)
-    {
-    }
-    WeakPtr<ProcFSProcessDirectory> m_process_directory;
-    mutable Mutex m_lock;
-};
-
-KResult ProcFSProcessStacks::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    MutexLocker locker(m_lock);
+    JsonArraySerializer array { builder };
-    auto parent_directory = m_process_directory.strong_ref();
+    auto thread = Thread::from_tid(thread_id);
-    if (parent_directory.is_null())
+    if (!thread)
-        return KResult(EINVAL);
-    callback({ ".", { fsid, component_index() }, 0 });
-    callback({ "..", { fsid, parent_directory->component_index() }, 0 });
-
-    auto process = parent_directory->associated_process();
-    if (process.is_null())
         return KResult(ESRCH);
-    process->for_each_thread([&](const Thread& thread) {
+    bool show_kernel_addresses = Process::current()->is_superuser();
+    bool kernel_address_added = false;
+    for (auto address : Processor::capture_stack_trace(*thread, 1024)) {
+        if (!show_kernel_addresses && !Memory::is_user_address(VirtualAddress { address })) {
+            if (kernel_address_added)
+                continue;
+            address = 0xdeadc0de;
+            kernel_address_added = true;
+        }
+        array.add(address);
+    }
+
+    array.finish();
+    return KSuccess;
+}
+
+InodeIndex Process::component_index() const
+{
+    return SegmentedProcFSIndex::build_segmented_index_for_pid_directory(pid());
+}
+
+NonnullRefPtr<Inode> Process::to_inode(const ProcFS& procfs_instance) const
+{
+    return ProcFSProcessDirectoryInode::create(procfs_instance, m_protected_values.pid);
+}
+
+KResult Process::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
+{
+    callback({ ".", { fsid, SegmentedProcFSIndex::build_segmented_index_for_pid_directory(pid()) }, 0 });
+    callback({ "..", { fsid, ProcFSComponentRegistry::the().root_directory().component_index() }, 0 });
+    callback({ "fd", { fsid, SegmentedProcFSIndex::build_segmented_index_for_sub_directory(pid(), SegmentedProcFSIndex::ProcessSubDirectory::FileDescriptions) }, 0 });
+    callback({ "stacks", { fsid, SegmentedProcFSIndex::build_segmented_index_for_sub_directory(pid(), SegmentedProcFSIndex::ProcessSubDirectory::Stacks) }, 0 });
+    callback({ "unveil", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::Unveil) }, 0 });
+    callback({ "pledge", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::Pledge) }, 0 });
+    callback({ "fds", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::FileDescriptions) }, 0 });
+    callback({ "exe", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::BinaryLink) }, 0 });
+    callback({ "cwd", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::CurrentWorkDirectoryLink) }, 0 });
+    callback({ "perf_events", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::PerformanceEvents) }, 0 });
+    callback({ "vm", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::VirtualMemoryStats) }, 0 });
+    callback({ "root", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(pid(), SegmentedProcFSIndex::MainProcessProperty::RootLink) }, 0 });
+    return KSuccess;
+}
+
+KResult Process::traverse_stacks_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
+{
+    callback({ ".", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property(pid(), SegmentedProcFSIndex::ProcessSubDirectory::Stacks, SegmentedProcFSIndex::MainProcessProperty::Reserved) }, 0 });
+    callback({ "..", { fsid, component_index() }, 0 });
+
+    for_each_thread([&](const Thread& thread) {
         int tid = thread.tid().value();
-        InodeIdentifier identifier = { fsid, thread.global_procfs_inode_index() };
+        InodeIdentifier identifier = { fsid, SegmentedProcFSIndex::build_segmented_index_for_thread_stack(pid(), thread.tid()) };
         callback({ String::number(tid), identifier, 0 });
     });
     return KSuccess;
 }
 
-RefPtr<ProcFSExposedComponent> ProcFSProcessStacks::lookup(StringView name)
+RefPtr<Inode> Process::lookup_stacks_directory(const ProcFS& procfs, StringView name) const
 {
-    MutexLocker locker(m_lock);
+    RefPtr<ProcFSProcessPropertyInode> thread_stack_inode;
-    auto parent_directory = m_process_directory.strong_ref();
-    if (parent_directory.is_null())
-        return nullptr;
-    auto process = parent_directory->associated_process();
-    if (process.is_null())
-        return nullptr;
-    RefPtr<ProcFSThreadStack> procfd_stack;
     // FIXME: Try to exit the loop earlier
-    process->for_each_thread([&](const Thread& thread) {
+    for_each_thread([&](const Thread& thread) {
         int tid = thread.tid().value();
+        VERIFY(!(tid < 0));
         if (name == String::number(tid)) {
-            procfd_stack = ProcFSThreadStack::create(*parent_directory, *this, thread);
+            thread_stack_inode = ProcFSProcessPropertyInode::create_for_thread_stack(procfs, thread.tid(), pid());
         }
     });
-    return procfd_stack;
+    return thread_stack_inode;
 }
 
-class ProcFSProcessFileDescriptions;
+KResultOr<size_t> Process::procfs_get_file_description_link(unsigned fd, KBufferBuilder& builder) const
-class ProcFSProcessFileDescription final : public ProcFSExposedLink {
-public:
-    // Note: we pass const ProcFSProcessFileDescriptions& just to enforce creation of this in the correct directory.
-    static NonnullRefPtr<ProcFSProcessFileDescription> create(unsigned fd_number, const FileDescription& fd, InodeIndex preallocated_index, const ProcFSProcessFileDescriptions&)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessFileDescription(fd_number, fd, preallocated_index));
-    }
-
-private:
-    explicit ProcFSProcessFileDescription(unsigned fd_number, const FileDescription& fd, InodeIndex preallocated_index)
-        : ProcFSExposedLink(String::formatted("{}", fd_number), preallocated_index)
-        , m_associated_file_description(fd)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        builder.append_bytes(m_associated_file_description->absolute_path().bytes());
-        return true;
-    }
-
-    NonnullRefPtr<FileDescription> m_associated_file_description;
-};
-
-class ProcFSProcessFileDescriptions final : public ProcFSExposedDirectory {
-    // Note: This directory is special, because everything that is created here is dynamic!
-    // This means we don't register anything in the m_components Vector, and every inode
-    // is created in runtime when called to get it
-    // Every ProcFSProcessFileDescription (that represents a file descriptor) is created only as a temporary object
-    // therefore, we don't use m_components so when we are done with the ProcFSProcessFileDescription object,
-    // It should be deleted (as soon as possible)
-public:
-    virtual KResult traverse_as_directory(unsigned, Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
-    virtual RefPtr<ProcFSExposedComponent> lookup(StringView name) override;
-
-    static NonnullRefPtr<ProcFSProcessFileDescriptions> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessFileDescriptions(parent_directory));
-    }
-
-    virtual void prepare_for_deletion() override
-    {
-        ProcFSExposedDirectory::prepare_for_deletion();
-        m_process_directory.clear();
-    }
-
-private:
-    explicit ProcFSProcessFileDescriptions(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedDirectory("fd"sv, parent_directory)
-        , m_process_directory(parent_directory)
-    {
-    }
-    WeakPtr<ProcFSProcessDirectory> m_process_directory;
-    mutable Mutex m_lock;
-};
-
-KResult ProcFSProcessFileDescriptions::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
 {
-    MutexLocker locker(m_lock);
+    auto file_description = m_fds.file_description(fd);
-    auto parent_directory = m_process_directory.strong_ref();
+    if (!file_description)
-    if (parent_directory.is_null())
+        return EBADF;
-        return KResult(EINVAL);
+    auto data = file_description->absolute_path();
-    callback({ ".", { fsid, component_index() }, 0 });
+    builder.append(data);
-    callback({ "..", { fsid, parent_directory->component_index() }, 0 });
+    return data.length();
+}
 
-    auto process = parent_directory->associated_process();
+KResult Process::traverse_file_descriptions_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
-    if (process.is_null())
+{
-        return KResult(ESRCH);
+    callback({ ".", { fsid, component_index() }, 0 });
+    callback({ "..", { fsid, component_index() }, 0 });
     size_t count = 0;
-    process->fds().enumerate([&](auto& file_description_metadata) {
+    fds().enumerate([&](auto& file_description_metadata) {
         if (!file_description_metadata.is_valid()) {
             count++;
             return;
         }
-        InodeIdentifier identifier = { fsid, file_description_metadata.global_procfs_inode_index() };
+        InodeIdentifier identifier = { fsid, SegmentedProcFSIndex::build_segmented_index_for_file_description(pid(), count) };
         callback({ String::number(count), identifier, 0 });
         count++;
     });
     return KSuccess;
 }
-RefPtr<ProcFSExposedComponent> ProcFSProcessFileDescriptions::lookup(StringView name)
+
+RefPtr<Inode> Process::lookup_file_descriptions_directory(const ProcFS& procfs, StringView name) const
 {
-    MutexLocker locker(m_lock);
+    RefPtr<ProcFSProcessPropertyInode> file_description_link;
-    auto parent_directory = m_process_directory.strong_ref();
-    if (parent_directory.is_null())
-        return nullptr;
-    auto process = parent_directory->associated_process();
-    if (process.is_null())
-        return nullptr;
-    RefPtr<ProcFSProcessFileDescription> procfd_fd;
     // FIXME: Try to exit the loop earlier
     size_t count = 0;
-    process->fds().enumerate([&](auto& file_description_metadata) {
+    fds().enumerate([&](auto& file_description_metadata) {
         if (!file_description_metadata.is_valid()) {
             count++;
             return;
         }
         if (name == String::number(count)) {
-            procfd_fd = ProcFSProcessFileDescription::create(count, *file_description_metadata.description(), file_description_metadata.global_procfs_inode_index(), *this);
+            file_description_link = ProcFSProcessPropertyInode::create_for_file_description_link(procfs, static_cast<unsigned>(count), pid());
         }
         count++;
     });
-    return procfd_fd;
+    return file_description_link;
 }
 
-class ProcFSProcessPledge final : public ProcFSProcessInformation {
+KResult Process::procfs_get_pledge_stats(KBufferBuilder& builder) const
-public:
+{
-    static NonnullRefPtr<ProcFSProcessPledge> create(const ProcFSProcessDirectory& parent_directory)
+    JsonObjectSerializer obj { builder };
-    {
+#define __ENUMERATE_PLEDGE_PROMISE(x) \
-        return adopt_ref(*new (nothrow) ProcFSProcessPledge(parent_directory));
+    if (has_promised(Pledge::x)) {    \
+        if (!builder.is_empty())      \
+            builder.append(' ');      \
+        builder.append(#x);           \
     }
-
+    if (has_promises()) {
-private:
+        StringBuilder builder;
-    explicit ProcFSProcessPledge(const ProcFSProcessDirectory& parent_directory)
+        ENUMERATE_PLEDGE_PROMISES
-        : ProcFSProcessInformation("pledge"sv, parent_directory)
+        obj.add("promises", builder.build());
-    {
     }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        JsonObjectSerializer obj { builder };
-#define __ENUMERATE_PLEDGE_PROMISE(x)       \
-    if (process->has_promised(Pledge::x)) { \
-        if (!builder.is_empty())            \
-            builder.append(' ');            \
-        builder.append(#x);                 \
-    }
-        if (process->has_promises()) {
-            StringBuilder builder;
-            ENUMERATE_PLEDGE_PROMISES
-            obj.add("promises", builder.build());
-        }
 #undef __ENUMERATE_PLEDGE_PROMISE
-        obj.finish();
+    obj.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessUnveil final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessUnveil> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessUnveil(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessUnveil(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("unveil"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        JsonArraySerializer array { builder };
-        for (auto& unveiled_path : process->unveiled_paths()) {
-            if (!unveiled_path.was_explicitly_unveiled())
-                continue;
-            auto obj = array.add_object();
-            obj.add("path", unveiled_path.path());
-            StringBuilder permissions_builder;
-            if (unveiled_path.permissions() & UnveilAccess::Read)
-                permissions_builder.append('r');
-            if (unveiled_path.permissions() & UnveilAccess::Write)
-                permissions_builder.append('w');
-            if (unveiled_path.permissions() & UnveilAccess::Execute)
-                permissions_builder.append('x');
-            if (unveiled_path.permissions() & UnveilAccess::CreateOrRemove)
-                permissions_builder.append('c');
-            if (unveiled_path.permissions() & UnveilAccess::Browse)
-                permissions_builder.append('b');
-            obj.add("permissions", permissions_builder.to_string());
-        }
-        array.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessPerformanceEvents final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessPerformanceEvents> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessPerformanceEvents(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessPerformanceEvents(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("perf_events"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        InterruptDisabler disabler;
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        if (!process->perf_events()) {
-            dbgln("ProcFS: No perf events for {}", process->pid());
-            return false;
-        }
-        return process->perf_events()->to_json(builder);
-    }
-};
-
-class ProcFSProcessOverallFileDescriptions final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessOverallFileDescriptions> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessOverallFileDescriptions(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessOverallFileDescriptions(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("fds"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        JsonArraySerializer array { builder };
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        if (process->fds().open_count() == 0) {
-            array.finish();
-            return true;
-        }
-
-        size_t count = 0;
-        process->fds().enumerate([&](auto& file_description_metadata) {
-            if (!file_description_metadata.is_valid()) {
-                count++;
-                return;
-            }
-            bool cloexec = file_description_metadata.flags() & FD_CLOEXEC;
-            RefPtr<FileDescription> description = file_description_metadata.description();
-            auto description_object = array.add_object();
-            description_object.add("fd", count);
-            description_object.add("absolute_path", description->absolute_path());
-            description_object.add("seekable", description->file().is_seekable());
-            description_object.add("class", description->file().class_name());
-            description_object.add("offset", description->offset());
-            description_object.add("cloexec", cloexec);
-            description_object.add("blocking", description->is_blocking());
-            description_object.add("can_read", description->can_read());
-            description_object.add("can_write", description->can_write());
-            count++;
-        });
-
-        array.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessRoot final : public ProcFSExposedLink {
-public:
-    static NonnullRefPtr<ProcFSProcessRoot> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessRoot(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessRoot(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedLink("root"sv)
-        , m_parent_process_directory(parent_directory)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        builder.append_bytes(process->root_directory_relative_to_global_root().absolute_path().to_byte_buffer());
-        return true;
-    }
-    WeakPtr<ProcFSProcessDirectory> m_parent_process_directory;
-};
-
-class ProcFSProcessVirtualMemory final : public ProcFSProcessInformation {
-public:
-    static NonnullRefPtr<ProcFSProcessRoot> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessVirtualMemory(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessVirtualMemory(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSProcessInformation("vm"sv, parent_directory)
-    {
-    }
-    virtual bool output(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        JsonArraySerializer array { builder };
-        {
-            ScopedSpinLock lock(process->address_space().get_lock());
-            for (auto& region : process->address_space().regions()) {
-                if (!region->is_user() && !Process::current()->is_superuser())
-                    continue;
-                auto region_object = array.add_object();
-                region_object.add("readable", region->is_readable());
-                region_object.add("writable", region->is_writable());
-                region_object.add("executable", region->is_executable());
-                region_object.add("stack", region->is_stack());
-                region_object.add("shared", region->is_shared());
-                region_object.add("syscall", region->is_syscall_region());
-                region_object.add("purgeable", region->vmobject().is_anonymous());
-                if (region->vmobject().is_anonymous()) {
-                    region_object.add("volatile", static_cast<Memory::AnonymousVMObject const&>(region->vmobject()).is_volatile());
-                }
-                region_object.add("cacheable", region->is_cacheable());
-                region_object.add("address", region->vaddr().get());
-                region_object.add("size", region->size());
-                region_object.add("amount_resident", region->amount_resident());
-                region_object.add("amount_dirty", region->amount_dirty());
-                region_object.add("cow_pages", region->cow_pages());
-                region_object.add("name", region->name());
-                region_object.add("vmobject", region->vmobject().class_name());
-
-                StringBuilder pagemap_builder;
-                for (size_t i = 0; i < region->page_count(); ++i) {
-                    auto* page = region->physical_page(i);
-                    if (!page)
-                        pagemap_builder.append('N');
-                    else if (page->is_shared_zero_page() || page->is_lazy_committed_page())
-                        pagemap_builder.append('Z');
-                    else
-                        pagemap_builder.append('P');
-                }
-                region_object.add("pagemap", pagemap_builder.to_string());
-            }
-        }
-        array.finish();
-        return true;
-    }
-};
-
-class ProcFSProcessCurrentWorkDirectory final : public ProcFSExposedLink {
-public:
-    static NonnullRefPtr<ProcFSProcessCurrentWorkDirectory> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessCurrentWorkDirectory(parent_directory));
-    }
-
-private:
-    explicit ProcFSProcessCurrentWorkDirectory(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedLink("cwd"sv)
-        , m_parent_process_directory(parent_directory)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        builder.append_bytes(process->current_directory().absolute_path().bytes());
-        return true;
-    }
-
-    WeakPtr<ProcFSProcessDirectory> m_parent_process_directory;
-};
-
-class ProcFSProcessBinary final : public ProcFSExposedLink {
-public:
-    static NonnullRefPtr<ProcFSProcessBinary> create(const ProcFSProcessDirectory& parent_directory)
-    {
-        return adopt_ref(*new (nothrow) ProcFSProcessBinary(parent_directory));
-    }
-
-    virtual mode_t required_mode() const override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        if (!process->executable())
-            return 0;
-        return ProcFSExposedComponent::required_mode();
-    }
-
-private:
-    explicit ProcFSProcessBinary(const ProcFSProcessDirectory& parent_directory)
-        : ProcFSExposedLink("exe"sv)
-        , m_parent_process_directory(parent_directory)
-    {
-    }
-    virtual bool acquire_link(KBufferBuilder& builder) override
-    {
-        auto parent_directory = m_parent_process_directory.strong_ref();
-        if (parent_directory.is_null())
-            return false;
-        auto process = parent_directory->associated_process();
-        if (process.is_null())
-            return false;
-        auto* custody = process->executable();
-        if (!custody)
-            return false;
-        builder.append(custody->absolute_path().bytes());
-        return true;
-    }
-
-    WeakPtr<ProcFSProcessDirectory> m_parent_process_directory;
-};
-
-void ProcFSProcessDirectory::on_attach()
-{
-    VERIFY(m_components.size() == 0);
-    m_components.append(ProcFSProcessPledge::create(*this));
-    m_components.append(ProcFSProcessUnveil::create(*this));
-    m_components.append(ProcFSProcessPerformanceEvents::create(*this));
-    m_components.append(ProcFSProcessFileDescriptions::create(*this));
-    m_components.append(ProcFSProcessOverallFileDescriptions::create(*this));
-    m_components.append(ProcFSProcessRoot::create(*this));
-    m_components.append(ProcFSProcessVirtualMemory::create(*this));
-    m_components.append(ProcFSProcessCurrentWorkDirectory::create(*this));
-    m_components.append(ProcFSProcessBinary::create(*this));
-    m_components.append(ProcFSProcessStacks::create(*this));
-}
-
-RefPtr<ProcFSExposedComponent> ProcFSProcessDirectory::lookup(StringView name)
-{
-    // Note: we need to allocate all sub components when doing a lookup, because
-    // for some reason, the caller may not call ProcFSInode::attach method before calling this.
-    if (m_components.size() == 0)
-        on_attach();
-    return ProcFSExposedDirectory::lookup(name);
-}
-
-KResult ProcFSProcessDirectory::refresh_data(FileDescription&) const
-{
-    if (m_components.size() != 0)
-        return KSuccess;
-    const_cast<ProcFSProcessDirectory&>(*this).on_attach();
     return KSuccess;
 }
 
-NonnullRefPtr<ProcFSProcessDirectory> ProcFSProcessDirectory::create(const Process& process)
+KResult Process::procfs_get_unveil_stats(KBufferBuilder& builder) const
 {
-    return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessDirectory(process)).release_nonnull();
+    JsonArraySerializer array { builder };
+    for (auto& unveiled_path : unveiled_paths()) {
+        if (!unveiled_path.was_explicitly_unveiled())
+            continue;
+        auto obj = array.add_object();
+        obj.add("path", unveiled_path.path());
+        StringBuilder permissions_builder;
+        if (unveiled_path.permissions() & UnveilAccess::Read)
+            permissions_builder.append('r');
+        if (unveiled_path.permissions() & UnveilAccess::Write)
+            permissions_builder.append('w');
+        if (unveiled_path.permissions() & UnveilAccess::Execute)
+            permissions_builder.append('x');
+        if (unveiled_path.permissions() & UnveilAccess::CreateOrRemove)
+            permissions_builder.append('c');
+        if (unveiled_path.permissions() & UnveilAccess::Browse)
+            permissions_builder.append('b');
+        obj.add("permissions", permissions_builder.to_string());
+    }
+    array.finish();
+    return KSuccess;
 }
 
-void ProcFSProcessDirectory::prepare_for_deletion()
+KResult Process::procfs_get_perf_events(KBufferBuilder& builder) const
 {
-    ProcFSExposedDirectory::prepare_for_deletion();
+    InterruptDisabler disabler;
-    m_associated_process.clear();
+    if (!const_cast<Process&>(*this).perf_events()) {
+        dbgln("ProcFS: No perf events for {}", pid());
+        return KResult(ENOBUFS);
+    }
+    return const_cast<Process&>(*this).perf_events()->to_json(builder) ? KSuccess : KResult(EINVAL);
 }
 
-ProcFSProcessDirectory::ProcFSProcessDirectory(const Process& process)
+KResult Process::procfs_get_fds_stats(KBufferBuilder& builder) const
-    : ProcFSExposedDirectory(String::formatted("{:d}", process.pid().value()), ProcFSComponentRegistry::the().root_directory())
-    , m_associated_process(process)
 {
+    JsonArraySerializer array { builder };
+    if (fds().open_count() == 0) {
+        array.finish();
+        return KSuccess;
+    }
+
+    size_t count = 0;
+    fds().enumerate([&](auto& file_description_metadata) {
+        if (!file_description_metadata.is_valid()) {
+            count++;
+            return;
+        }
+        bool cloexec = file_description_metadata.flags() & FD_CLOEXEC;
+        RefPtr<FileDescription> description = file_description_metadata.description();
+        auto description_object = array.add_object();
+        description_object.add("fd", count);
+        description_object.add("absolute_path", description->absolute_path());
+        description_object.add("seekable", description->file().is_seekable());
+        description_object.add("class", description->file().class_name());
+        description_object.add("offset", description->offset());
+        description_object.add("cloexec", cloexec);
+        description_object.add("blocking", description->is_blocking());
+        description_object.add("can_read", description->can_read());
+        description_object.add("can_write", description->can_write());
+        count++;
+    });
+
+    array.finish();
+    return KSuccess;
+}
+
+KResult Process::procfs_get_root_link(KBufferBuilder& builder) const
+{
+    builder.append_bytes(const_cast<Process&>(*this).root_directory_relative_to_global_root().absolute_path().to_byte_buffer());
+    return KSuccess;
+}
+
+KResult Process::procfs_get_virtual_memory_stats(KBufferBuilder& builder) const
+{
+    JsonArraySerializer array { builder };
+    {
+        ScopedSpinLock lock(address_space().get_lock());
+        for (auto& region : address_space().regions()) {
+            if (!region->is_user() && !Process::current()->is_superuser())
+                continue;
+            auto region_object = array.add_object();
+            region_object.add("readable", region->is_readable());
+            region_object.add("writable", region->is_writable());
+            region_object.add("executable", region->is_executable());
+            region_object.add("stack", region->is_stack());
+            region_object.add("shared", region->is_shared());
+            region_object.add("syscall", region->is_syscall_region());
+            region_object.add("purgeable", region->vmobject().is_anonymous());
+            if (region->vmobject().is_anonymous()) {
+                region_object.add("volatile", static_cast<Memory::AnonymousVMObject const&>(region->vmobject()).is_volatile());
+            }
+            region_object.add("cacheable", region->is_cacheable());
+            region_object.add("address", region->vaddr().get());
+            region_object.add("size", region->size());
+            region_object.add("amount_resident", region->amount_resident());
+            region_object.add("amount_dirty", region->amount_dirty());
+            region_object.add("cow_pages", region->cow_pages());
+            region_object.add("name", region->name());
+            region_object.add("vmobject", region->vmobject().class_name());
+
+            StringBuilder pagemap_builder;
+            for (size_t i = 0; i < region->page_count(); ++i) {
+                auto* page = region->physical_page(i);
+                if (!page)
+                    pagemap_builder.append('N');
+                else if (page->is_shared_zero_page() || page->is_lazy_committed_page())
+                    pagemap_builder.append('Z');
+                else
+                    pagemap_builder.append('P');
+            }
+            region_object.add("pagemap", pagemap_builder.to_string());
+        }
+    }
+    array.finish();
+    return KSuccess;
+}
+
+KResult Process::procfs_get_current_work_directory_link(KBufferBuilder& builder) const
+{
+    builder.append_bytes(const_cast<Process&>(*this).current_directory().absolute_path().bytes());
+    return KSuccess;
+}
+
+mode_t Process::binary_link_required_mode() const
+{
+    if (!executable())
+        return 0;
+    return ProcFSExposedComponent::required_mode();
+}
+
+KResult Process::procfs_get_binary_link(KBufferBuilder& builder) const
+{
+    auto* custody = executable();
+    if (!custody)
+        return KResult(ENOEXEC);
+    builder.append(custody->absolute_path().bytes());
+    return KSuccess;
 }
 
 }

Kernel/Thread.cpp

@@ -62,7 +62,6 @@ Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Memory::Region> ker
     , m_kernel_stack_region(move(kernel_stack_region))
     , m_name(move(name))
     , m_block_timer(block_timer)
-    , m_global_procfs_inode_index(ProcFSComponentRegistry::the().allocate_inode_index())
 {
     bool is_first_thread = m_process->add_thread(*this);
     if (is_first_thread) {

Kernel/Thread.h

@@ -1213,8 +1213,6 @@ public:
     bool is_profiling_suppressed() const { return m_is_profiling_suppressed; }
     void set_profiling_suppressed() { m_is_profiling_suppressed = true; }
 
-    InodeIndex global_procfs_inode_index() const { return m_global_procfs_inode_index; }
-
     String backtrace();
 
 private:
@@ -1364,10 +1362,6 @@ private:
 
     RefPtr<Timer> m_block_timer;
 
-    // Note: This is needed so when we generate thread stack inodes for ProcFS, we know that
-    // we assigned a global Inode index to it so we can use it later
-    InodeIndex m_global_procfs_inode_index;
-
     bool m_is_profiling_suppressed { false };
 
     void yield_and_release_relock_big_lock();