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Kernel: Make Region single-owner instead of ref-counted

Browse source 
This simplifies the ownership model and makes Region easier to reason
about. Userspace Regions are now primarily kept by Process::m_regions.

Kernel Regions are kept in various OwnPtr<Regions>'s.

Regions now only ever get unmapped when they are destroyed.
This commit is contained in:
Andreas Kling 2019-09-27 14:19:07 +02:00
parent 7a7f6a24e9
commit 7f9a33dba1
9 changed files with 44 additions and 41 deletions
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2
AK/ELF/ELFLoader.h
View file

@ -54,7 +54,7 @@ private:
const char* name;
};
#ifdef KERNEL
mutable RefPtr<Region> m_sorted_symbols_region;
mutable OwnPtr<Region> m_sorted_symbols_region;
#else
mutable Vector<SortedSymbol> m_sorted_symbols;
#endif

6
Kernel/KBuffer.h
View file

@ -21,7 +21,7 @@ public:
{
auto region = MM.allocate_kernel_region(PAGE_ROUND_UP(size), "KBuffer", false, false);
ASSERT(region);
return adopt(*new KBufferImpl(*region, size));
return adopt(*new KBufferImpl(region.release_nonnull(), size));
}
static NonnullRefPtr<KBufferImpl> copy(const void* data, size_t size)
@ -43,14 +43,14 @@ public:
}
private:
explicit KBufferImpl(NonnullRefPtr<Region>&& region, size_t size)
explicit KBufferImpl(NonnullOwnPtr<Region>&& region, size_t size)
: m_size(size)
, m_region(move(region))
{
}
size_t m_size { 0 };
NonnullRefPtr<Region> m_region;
NonnullOwnPtr<Region> m_region;
};
class KBuffer {

21
Kernel/Process.cpp
View file

@ -152,7 +152,6 @@ bool Process::deallocate_region(Region& region)
InterruptDisabler disabler;
for (int i = 0; i < m_regions.size(); ++i) {
if (&m_regions[i] == &region) {
MM.unmap_region(region);
m_regions.remove(i);
return true;
}
@ -305,12 +304,11 @@ Process* Process::fork(RegisterDump& regs)
#ifdef FORK_DEBUG
dbg() << "fork: cloning Region{" << &region << "} '" << region.name() << "' @ " << region.vaddr();
#endif
auto cloned_region = region.clone();
child->m_regions.append(move(cloned_region));
child->m_regions.append(region.clone());
MM.map_region(*child, child->m_regions.last());
if (&region == m_master_tls_region)
child->m_master_tls_region = child->m_regions.last();
child->m_master_tls_region = &child->m_regions.last();
}
for (auto gid : m_gids)
@ -401,10 +399,14 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
ASSERT(description->inode());
auto vmo = InodeVMObject::create_with_inode(*description->inode());
RefPtr<Region> region = allocate_region_with_vmo(VirtualAddress(), metadata.size, vmo, 0, description->absolute_path(), PROT_READ);
auto* region = allocate_region_with_vmo(VirtualAddress(), metadata.size, vmo, 0, description->absolute_path(), PROT_READ);
ASSERT(region);
RefPtr<Region> master_tls_region;
// NOTE: We yank this out of 'm_regions' since we're about to manipulate the vector
// and we don't want it getting lost.
auto executable_region = m_regions.take_last();
Region* master_tls_region { nullptr };
size_t master_tls_size = 0;
size_t master_tls_alignment = 0;
@ -412,7 +414,7 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
{
// Okay, here comes the sleight of hand, pay close attention..
auto old_regions = move(m_regions);
m_regions.append(*region);
m_regions.append(move(executable_region));
loader = make<ELFLoader>(region->vaddr().as_ptr());
loader->map_section_hook = [&](VirtualAddress vaddr, size_t size, size_t alignment, size_t offset_in_image, bool is_readable, bool is_writable, bool is_executable, const String& name) {
ASSERT(size);
@ -451,6 +453,7 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
// FIXME: RAII this somehow instead.
ASSERT(&current->process() == this);
MM.enter_process_paging_scope(*this);
executable_region = m_regions.take_first();
m_regions = move(old_regions);
kprintf("do_exec: Failure loading %s\n", path.characters());
return -ENOEXEC;
@ -464,7 +467,7 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
m_executable = description->custody();
// Copy of the master TLS region that we will clone for new threads
m_master_tls_region = master_tls_region.ptr();
m_master_tls_region = master_tls_region;
if (metadata.is_setuid())
m_euid = metadata.uid;
@ -823,7 +826,7 @@ void create_signal_trampolines()
InterruptDisabler disabler;
// NOTE: We leak this region.
auto* trampoline_region = MM.allocate_user_accessible_kernel_region(PAGE_SIZE, "Signal trampolines").leak_ref();
auto* trampoline_region = MM.allocate_user_accessible_kernel_region(PAGE_SIZE, "Signal trampolines").leak_ptr();
g_return_to_ring3_from_signal_trampoline = trampoline_region->vaddr();
u8* trampoline = (u8*)asm_signal_trampoline;

8
Kernel/Process.h
View file

@ -1,8 +1,8 @@
#pragma once
#include <AK/String.h>
#include <AK/InlineLinkedList.h>
#include <AK/NonnullRefPtrVector.h>
#include <AK/String.h>
#include <AK/Types.h>
#include <AK/Vector.h>
#include <AK/WeakPtr.h>
@ -234,7 +234,7 @@ public:
void set_tty(TTY* tty) { m_tty = tty; }
size_t region_count() const { return m_regions.size(); }
const NonnullRefPtrVector<Region>& regions() const { return m_regions; }
const NonnullOwnPtrVector<Region>& regions() const { return m_regions; }
void dump_regions();
ProcessTracer* tracer() { return m_tracer.ptr(); }
@ -356,7 +356,7 @@ private:
Region* region_from_range(const Range&);
Region* region_containing(const Range&);
NonnullRefPtrVector<Region> m_regions;
NonnullOwnPtrVector<Region> m_regions;
pid_t m_ppid { 0 };
mode_t m_umask { 022 };
@ -372,7 +372,7 @@ private:
RefPtr<ProcessTracer> m_tracer;
OwnPtr<ELFLoader> m_elf_loader;
RefPtr<Region> m_master_tls_region;
Region* m_master_tls_region { nullptr };
size_t m_master_tls_size { 0 };
size_t m_master_tls_alignment { 0 };

4
Kernel/Thread.h
View file

@ -327,8 +327,8 @@ private:
u32 m_signal_mask { 0 };
u32 m_kernel_stack_base { 0 };
u32 m_kernel_stack_top { 0 };
RefPtr<Region> m_userspace_stack_region;
RefPtr<Region> m_kernel_stack_region;
Region* m_userspace_stack_region { nullptr };
OwnPtr<Region> m_kernel_stack_region;
VirtualAddress m_thread_specific_data;
SignalActionData m_signal_action_data[32];
Blocker* m_blocker { nullptr };

6
Kernel/VM/MemoryManager.cpp
View file

@ -444,13 +444,13 @@ PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
return PageFaultResponse::ShouldCrash;
}
RefPtr<Region> MemoryManager::allocate_kernel_region(size_t size, const StringView& name, bool user_accessible, bool should_commit)
OwnPtr<Region> MemoryManager::allocate_kernel_region(size_t size, const StringView& name, bool user_accessible, bool should_commit)
{
InterruptDisabler disabler;
ASSERT(!(size % PAGE_SIZE));
auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
ASSERT(range.is_valid());
RefPtr<Region> region;
OwnPtr<Region> region;
if (user_accessible)
region = Region::create_user_accessible(range, name, PROT_READ | PROT_WRITE | PROT_EXEC, false);
else
@ -462,7 +462,7 @@ RefPtr<Region> MemoryManager::allocate_kernel_region(size_t size, const StringVi
return region;
}
RefPtr<Region> MemoryManager::allocate_user_accessible_kernel_region(size_t size, const StringView& name)
OwnPtr<Region> MemoryManager::allocate_user_accessible_kernel_region(size_t size, const StringView& name)
{
return allocate_kernel_region(size, name, true);
}

4
Kernel/VM/MemoryManager.h
View file

@ -71,8 +71,8 @@ public:
void map_for_kernel(VirtualAddress, PhysicalAddress);
RefPtr<Region> allocate_kernel_region(size_t, const StringView& name, bool user_accessible = false, bool should_commit = true);
RefPtr<Region> allocate_user_accessible_kernel_region(size_t, const StringView& name);
OwnPtr<Region> allocate_kernel_region(size_t, const StringView& name, bool user_accessible = false, bool should_commit = true);
OwnPtr<Region> allocate_user_accessible_kernel_region(size_t, const StringView& name);
void map_region_at_address(PageDirectory&, Region&, VirtualAddress);
unsigned user_physical_pages() const { return m_user_physical_pages; }

18
Kernel/VM/Region.cpp
View file

@ -50,7 +50,7 @@ Region::~Region()
MM.unregister_region(*this);
}
NonnullRefPtr<Region> Region::clone()
NonnullOwnPtr<Region> Region::clone()
{
ASSERT(current);
@ -123,30 +123,30 @@ size_t Region::amount_shared() const
return bytes;
}
NonnullRefPtr<Region> Region::create_user_accessible(const Range& range, const StringView& name, u8 access, bool cow)
NonnullOwnPtr<Region> Region::create_user_accessible(const Range& range, const StringView& name, u8 access, bool cow)
{
auto region = adopt(*new Region(range, name, access, cow));
auto region = make<Region>(range, name, access, cow);
region->m_user_accessible = true;
return region;
}
NonnullRefPtr<Region> Region::create_user_accessible(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const StringView& name, u8 access, bool cow)
NonnullOwnPtr<Region> Region::create_user_accessible(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const StringView& name, u8 access, bool cow)
{
auto region = adopt(*new Region(range, move(vmobject), offset_in_vmobject, name, access, cow));
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cow);
region->m_user_accessible = true;
return region;
}
NonnullRefPtr<Region> Region::create_user_accessible(const Range& range, NonnullRefPtr<Inode> inode, const StringView& name, u8 access, bool cow)
NonnullOwnPtr<Region> Region::create_user_accessible(const Range& range, NonnullRefPtr<Inode> inode, const StringView& name, u8 access, bool cow)
{
auto region = adopt(*new Region(range, move(inode), name, access, cow));
auto region = make<Region>(range, move(inode), name, access, cow);
region->m_user_accessible = true;
return region;
}
NonnullRefPtr<Region> Region::create_kernel_only(const Range& range, const StringView& name, u8 access, bool cow)
NonnullOwnPtr<Region> Region::create_kernel_only(const Range& range, const StringView& name, u8 access, bool cow)
{
auto region = adopt(*new Region(range, name, access, cow));
auto region = make<Region>(range, name, access, cow);
region->m_user_accessible = false;
return region;
}

16
Kernel/VM/Region.h
View file

@ -10,8 +10,7 @@
class Inode;
class VMObject;
class Region final : public RefCounted<Region>
, public InlineLinkedListNode<Region> {
class Region final : public InlineLinkedListNode<Region> {
friend class MemoryManager;
MAKE_SLAB_ALLOCATED(Region)
@ -22,10 +21,10 @@ public:
Execute = 4,
};
static NonnullRefPtr<Region> create_user_accessible(const Range&, const StringView& name, u8 access, bool cow = false);
static NonnullRefPtr<Region> create_user_accessible(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cow = false);
static NonnullRefPtr<Region> create_user_accessible(const Range&, NonnullRefPtr<Inode>, const StringView& name, u8 access, bool cow = false);
static NonnullRefPtr<Region> create_kernel_only(const Range&, const StringView& name, u8 access, bool cow = false);
static NonnullOwnPtr<Region> create_user_accessible(const Range&, const StringView& name, u8 access, bool cow = false);
static NonnullOwnPtr<Region> create_user_accessible(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cow = false);
static NonnullOwnPtr<Region> create_user_accessible(const Range&, NonnullRefPtr<Inode>, const StringView& name, u8 access, bool cow = false);
static NonnullOwnPtr<Region> create_kernel_only(const Range&, const StringView& name, u8 access, bool cow = false);
~Region();
@ -48,7 +47,7 @@ public:
bool is_user_accessible() const { return m_user_accessible; }
NonnullRefPtr<Region> clone();
NonnullOwnPtr<Region> clone();
bool contains(VirtualAddress vaddr) const
{
@ -114,11 +113,12 @@ public:
Region* m_next { nullptr };
Region* m_prev { nullptr };
private:
// NOTE: These are public so we can make<> them.
Region(const Range&, const String&, u8 access, bool cow = false);
Region(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmo, const String&, u8 access, bool cow = false);
Region(const Range&, RefPtr<Inode>&&, const String&, u8 access, bool cow = false);
private:
RefPtr<PageDirectory> m_page_directory;
Range m_range;
size_t m_offset_in_vmo { 0 };