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Kernel: Stop taking MM lock while using regular quickmaps

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You're still required to disable interrupts though, as the mappings are
per-CPU. This exposed the fact that our CR3 lookup map is insufficiently
protected (but we'll address that in a separate commit.)
This commit is contained in:
Andreas Kling 2022-08-22 15:23:32 +02:00
parent c8375c51ff
commit 6cd3695761
5 changed files with 15 additions and 14 deletions
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8
Kernel/Memory/MemoryManager.cpp
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@ -8,6 +8,7 @@
#include <AK/Memory.h>
#include <AK/StringView.h>
#include <Kernel/Arch/CPU.h>
#include <Kernel/Arch/InterruptDisabler.h>
#include <Kernel/Arch/PageDirectory.h>
#include <Kernel/Arch/PageFault.h>
#include <Kernel/Arch/RegisterState.h>
@ -880,7 +881,7 @@ void MemoryManager::deallocate_physical_page(PhysicalAddress paddr)
LockRefPtr<PhysicalPage> MemoryManager::find_free_physical_page(bool committed)
{
VERIFY(s_mm_lock.is_locked());
SpinlockLocker mm_locker(s_mm_lock);
LockRefPtr<PhysicalPage> page;
if (committed) {
// Draw from the committed pages pool. We should always have these pages available
@ -905,9 +906,9 @@ LockRefPtr<PhysicalPage> MemoryManager::find_free_physical_page(bool committed)
NonnullLockRefPtr<PhysicalPage> MemoryManager::allocate_committed_physical_page(Badge<CommittedPhysicalPageSet>, ShouldZeroFill should_zero_fill)
{
SpinlockLocker lock(s_mm_lock);
auto page = find_free_physical_page(true);
if (should_zero_fill == ShouldZeroFill::Yes) {
InterruptDisabler disabler;
auto* ptr = quickmap_page(*page);
memset(ptr, 0, PAGE_SIZE);
unquickmap_page();
@ -1069,7 +1070,6 @@ PageTableEntry* MemoryManager::quickmap_pt(PhysicalAddress pt_paddr)
u8* MemoryManager::quickmap_page(PhysicalAddress const& physical_address)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(s_mm_lock.is_locked_by_current_processor());
auto& mm_data = get_data();
mm_data.m_quickmap_prev_flags = mm_data.m_quickmap_in_use.lock();
@ -1090,7 +1090,6 @@ u8* MemoryManager::quickmap_page(PhysicalAddress const& physical_address)
void MemoryManager::unquickmap_page()
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(s_mm_lock.is_locked_by_current_processor());
auto& mm_data = get_data();
VERIFY(mm_data.m_quickmap_in_use.is_locked());
VirtualAddress vaddr(KERNEL_QUICKMAP_PER_CPU_BASE + Processor::current_id() * PAGE_SIZE);
@ -1184,7 +1183,6 @@ void CommittedPhysicalPageSet::uncommit_one()
void MemoryManager::copy_physical_page(PhysicalPage& physical_page, u8 page_buffer[PAGE_SIZE])
{
SpinlockLocker locker(s_mm_lock);
auto* quickmapped_page = quickmap_page(physical_page);
memcpy(page_buffer, quickmapped_page, PAGE_SIZE);
unquickmap_page();