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LibWeb: Make VM allocation atomic for kernel regions

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Instead of first allocating the VM range, and then inserting a region
with that range into the MM region tree, we now do both things in a
single atomic operation:

    - RegionTree::place_anywhere(Region&, size, alignment)
    - RegionTree::place_specifically(Region&, address, size)

To reduce the number of things we do while locking the region tree,
we also require callers to provide a constructed Region object.
This commit is contained in:
Andreas Kling 2022-04-03 15:27:47 +02:00
parent cbf52d474c
commit e852a69a06
7 changed files with 85 additions and 57 deletions
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30
Kernel/Memory/Region.cpp
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@ -22,11 +22,21 @@
namespace Kernel::Memory {
Region::Region(VirtualRange const& range)
: m_range(range)
Region::Region()
: m_range(VirtualRange({}, 0))
{
if (is_kernel())
MM.register_kernel_region(*this);
}
Region::Region(NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable cacheable, bool shared)
: m_range(VirtualRange({}, 0))
, m_offset_in_vmobject(offset_in_vmobject)
, m_vmobject(move(vmobject))
, m_name(move(name))
, m_access(access | ((access & 0x7) << 4))
, m_shared(shared)
, m_cacheable(cacheable == Cacheable::Yes)
{
m_vmobject->add_region(*this);
}
Region::Region(VirtualRange const& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable cacheable, bool shared)
@ -43,9 +53,6 @@ Region::Region(VirtualRange const& range, NonnullRefPtr<VMObject> vmobject, size
VERIFY((m_range.size() % PAGE_SIZE) == 0);
m_vmobject->add_region(*this);
if (is_kernel())
MM.register_kernel_region(*this);
}
Region::~Region()
@ -72,9 +79,14 @@ Region::~Region()
}
}
ErrorOr<NonnullOwnPtr<Region>> Region::create_unbacked(VirtualRange const& range)
ErrorOr<NonnullOwnPtr<Region>> Region::create_unbacked()
{
return adopt_nonnull_own_or_enomem(new (nothrow) Region(range));
return adopt_nonnull_own_or_enomem(new (nothrow) Region);
}
ErrorOr<NonnullOwnPtr<Region>> Region::create_unplaced(NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable cacheable)
{
return adopt_nonnull_own_or_enomem(new (nothrow) Region(move(vmobject), offset_in_vmobject, move(name), access, cacheable, false));
}
ErrorOr<NonnullOwnPtr<Region>> Region::try_clone()