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

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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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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 };