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Kernel: Unmap Prekernel pages after they are no longer needed

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The Prekernel's memory is only accessed until MemoryManager has been
initialized. Keeping them around afterwards is both unnecessary and bad,
as it prevents the userland from using the 0x100000-0x155000 virtual
address range.

Co-authored-by: Idan Horowitz <idan.horowitz@gmail.com>
This commit is contained in:
Daniel Bertalan 2021-12-19 01:15:12 +01:00 • committed by Brian Gianforcaro
parent 2f1b4b8a81
commit 4fc28bfe02
4 changed files with 31 additions and 8 deletions
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15
Kernel/Memory/MemoryManager.h
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@ -49,19 +49,19 @@ inline FlatPtr virtual_to_low_physical(FlatPtr virtual_)
enum class UsedMemoryRangeType {
LowMemory = 0,
Prekernel,
Kernel,
BootModule,
PhysicalPages,
__Count
};
static constexpr StringView UserMemoryRangeTypeNames[] {
"Low memory",
"Prekernel",
"Kernel",
"Boot module",
"Physical Pages"
};
static_assert(array_size(UserMemoryRangeTypeNames) == to_underlying(UsedMemoryRangeType::__Count));
struct UsedMemoryRange {
UsedMemoryRangeType type {};
@ -159,6 +159,7 @@ public:
void set_page_writable_direct(VirtualAddress, bool);
void protect_readonly_after_init_memory();
void unmap_prekernel();
void unmap_text_after_init();
void protect_ksyms_after_init();
@ -276,7 +277,15 @@ private:
PageTableEntry* pte(PageDirectory&, VirtualAddress);
PageTableEntry* ensure_pte(PageDirectory&, VirtualAddress);
void release_pte(PageDirectory&, VirtualAddress, bool);
enum class IsLastPTERelease {
Yes,
No
};
enum class UnsafeIgnoreMissingPageTable {
Yes,
No
};
void release_pte(PageDirectory&, VirtualAddress, IsLastPTERelease, UnsafeIgnoreMissingPageTable = UnsafeIgnoreMissingPageTable::No);
RefPtr<PageDirectory> m_kernel_page_directory;