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Kernel: Add mechanism to identity map the lowest 2MB

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Tom 2020-06-01 22:55:09 -06:00 • committed by Andreas Kling
parent 19190267a6
commit 841364b609
7 changed files with 40 additions and 12 deletions
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18
Kernel/VM/MemoryManager.cpp
View file

@ -211,8 +211,6 @@ void MemoryManager::initialize()
Region* MemoryManager::kernel_region_from_vaddr(VirtualAddress vaddr)
{
if (vaddr.get() < 0xc0000000)
return nullptr;
for (auto& region : MM.m_kernel_regions) {
if (region.contains(vaddr))
return &region;
@ -318,6 +316,18 @@ OwnPtr<Region> MemoryManager::allocate_kernel_region(PhysicalAddress paddr, size
return allocate_kernel_region_with_vmobject(range, *vmobject, name, access, user_accessible, cacheable);
}
OwnPtr<Region> MemoryManager::allocate_kernel_region_identity(PhysicalAddress paddr, size_t size, const StringView& name, u8 access, bool user_accessible, bool cacheable)
{
ASSERT(!(size % PAGE_SIZE));
auto range = kernel_page_directory().identity_range_allocator().allocate_specific(VirtualAddress(paddr.get()), size);
if (!range.is_valid())
return nullptr;
auto vmobject = AnonymousVMObject::create_for_physical_range(paddr, size);
if (!vmobject)
return nullptr;
return allocate_kernel_region_with_vmobject(range, *vmobject, name, access, user_accessible, cacheable);
}
OwnPtr<Region> MemoryManager::allocate_user_accessible_kernel_region(size_t size, const StringView& name, u8 access, bool cacheable)
{
return allocate_kernel_region(size, name, access, true, true, cacheable);
@ -665,7 +675,7 @@ void MemoryManager::unregister_vmobject(VMObject& vmobject)
void MemoryManager::register_region(Region& region)
{
InterruptDisabler disabler;
if (region.vaddr().get() >= 0xc0000000)
if (region.is_kernel())
m_kernel_regions.append(&region);
else
m_user_regions.append(&region);
@ -674,7 +684,7 @@ void MemoryManager::register_region(Region& region)
void MemoryManager::unregister_region(Region& region)
{
InterruptDisabler disabler;
if (region.vaddr().get() >= 0xc0000000)
if (region.is_kernel())
m_kernel_regions.remove(&region);
else
m_user_regions.remove(&region);

5
Kernel/VM/MemoryManager.h
View file

@ -107,6 +107,7 @@ public:
OwnPtr<Region> allocate_contiguous_kernel_region(size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
OwnPtr<Region> allocate_kernel_region(size_t, const StringView& name, u8 access, bool user_accessible = false, bool should_commit = true, bool cacheable = true);
OwnPtr<Region> allocate_kernel_region(PhysicalAddress, size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
OwnPtr<Region> allocate_kernel_region_identity(PhysicalAddress, size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
OwnPtr<Region> allocate_kernel_region_with_vmobject(VMObject&, size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
OwnPtr<Region> allocate_kernel_region_with_vmobject(const Range&, VMObject&, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
OwnPtr<Region> allocate_user_accessible_kernel_region(size_t, const StringView& name, u8 access, bool cacheable = true);
@ -143,6 +144,8 @@ public:
PhysicalPage& shared_zero_page() { return *m_shared_zero_page; }
PageDirectory& kernel_page_directory() { return *m_kernel_page_directory; }
private:
MemoryManager();
~MemoryManager();
@ -177,8 +180,6 @@ private:
PageDirectoryEntry* quickmap_pd(PageDirectory&, size_t pdpt_index);
PageTableEntry* quickmap_pt(PhysicalAddress);
PageDirectory& kernel_page_directory() { return *m_kernel_page_directory; }
const PageTableEntry* pte(const PageDirectory&, VirtualAddress);
PageTableEntry& ensure_pte(PageDirectory&, VirtualAddress);

1
Kernel/VM/PageDirectory.cpp
View file

@ -59,6 +59,7 @@ extern "C" PageDirectoryEntry boot_pd3[1024];
PageDirectory::PageDirectory()
{
m_range_allocator.initialize_with_range(VirtualAddress(0xc0800000), 0x3f000000);
m_identity_range_allocator.initialize_with_range(VirtualAddress(FlatPtr(0x00000000)), 0x00200000);
// Adopt the page tables already set up by boot.S
PhysicalAddress boot_pdpt_paddr(virtual_to_low_physical((FlatPtr)boot_pdpt));

2
Kernel/VM/PageDirectory.h
View file

@ -52,6 +52,7 @@ public:
u32 cr3() const { return m_directory_table->paddr().get(); }
RangeAllocator& range_allocator() { return m_range_allocator; }
RangeAllocator& identity_range_allocator() { return m_identity_range_allocator; }
Process* process() { return m_process; }
const Process* process() const { return m_process; }
@ -62,6 +63,7 @@ private:
Process* m_process { nullptr };
RangeAllocator m_range_allocator;
RangeAllocator m_identity_range_allocator;
RefPtr<PhysicalPage> m_directory_table;
RefPtr<PhysicalPage> m_directory_pages[4];
HashMap<unsigned, RefPtr<PhysicalPage>> m_physical_pages;

5
Kernel/VM/RangeAllocator.h
View file

@ -90,6 +90,11 @@ public:
void dump() const;
bool contains(const Range& range) const
{
return m_total_range.contains(range);
}
private:
void carve_at_index(int, const Range&);

15
Kernel/VM/Region.cpp
View file

@ -40,13 +40,14 @@
namespace Kernel {
Region::Region(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, u8 access, bool cacheable)
Region::Region(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, u8 access, bool cacheable, bool kernel)
: m_range(range)
, m_offset_in_vmobject(offset_in_vmobject)
, m_vmobject(move(vmobject))
, m_name(name)
, m_access(access)
, m_cacheable(cacheable)
, m_kernel(kernel)
{
MM.register_region(*this);
}
@ -186,14 +187,14 @@ size_t Region::amount_shared() const
NonnullOwnPtr<Region> Region::create_user_accessible(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable)
{
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable);
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable, false);
region->m_user_accessible = true;
return region;
}
NonnullOwnPtr<Region> Region::create_kernel_only(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable)
{
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable);
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable, true);
region->m_user_accessible = false;
return region;
}
@ -268,8 +269,12 @@ void Region::unmap(ShouldDeallocateVirtualMemoryRange deallocate_range)
dbg() << "MM: >> Unmapped " << vaddr << " => P" << String::format("%p", page ? page->paddr().get() : 0) << " <<";
#endif
}
if (deallocate_range == ShouldDeallocateVirtualMemoryRange::Yes)
m_page_directory->range_allocator().deallocate(range());
if (deallocate_range == ShouldDeallocateVirtualMemoryRange::Yes) {
if (m_page_directory->range_allocator().contains(range()))
m_page_directory->range_allocator().deallocate(range());
else
m_page_directory->identity_range_allocator().deallocate(range());
}
m_page_directory = nullptr;
}

6
Kernel/VM/Region.h
View file

@ -95,6 +95,9 @@ public:
bool is_user_accessible() const { return m_user_accessible; }
void set_user_accessible(bool b) { m_user_accessible = b; }
bool is_kernel() const { return m_kernel || vaddr().get() >= 0xc0000000; }
void set_kernel(bool kernel) { m_kernel = kernel; }
PageFaultResponse handle_fault(const PageFault&);
NonnullOwnPtr<Region> clone();
@ -178,7 +181,7 @@ public:
Region* m_prev { nullptr };
// NOTE: These are public so we can make<> them.
Region(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String&, u8 access, bool cacheable);
Region(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String&, u8 access, bool cacheable, bool kernel);
void set_inherit_mode(InheritMode inherit_mode) { m_inherit_mode = inherit_mode; }
@ -211,6 +214,7 @@ private:
bool m_cacheable : 1 { false };
bool m_stack : 1 { false };
bool m_mmap : 1 { false };
bool m_kernel : 1 { false };
mutable OwnPtr<Bitmap> m_cow_map;
};