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Kernel: Minor MM optimization for SMP

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MemoryManager::quickmap_pd and MemoryManager::quickmap_pt can only
be called by one processor at the time anyway, since anything using
these must have the MM lock held. So, no need to inform the other
CPUs to flush their TLBs, we can just flush our own.
This commit is contained in:
Tom 2020-07-06 09:11:52 -06:00 committed by Andreas Kling
parent bc107d0b33
commit 655f4daeb1
Notes: sideshowbarker 2024-07-19 05:06:33 +09:00 
Author: https://github.com/tomuta
Commit: https://github.com/SerenityOS/serenity/commit/655f4daeb1c
Pull-request: https://github.com/SerenityOS/serenity/pull/2712
2 changed files with 18 additions and 12 deletions
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23
Kernel/VM/MemoryManager.cpp
View File

@ -60,6 +60,7 @@ MemoryManager& MM
MemoryManager::MemoryManager()
{
ScopedSpinLock lock(s_mm_lock);
m_kernel_page_directory = PageDirectory::create_kernel_page_directory();
parse_memory_map();
write_cr3(kernel_page_directory().cr3());
@ -165,7 +166,7 @@ void MemoryManager::parse_memory_map()
const PageTableEntry* MemoryManager::pte(const PageDirectory& page_directory, VirtualAddress vaddr)
{
ASSERT_INTERRUPTS_DISABLED();
ScopedSpinLock lock(s_mm_lock);
ASSERT(s_mm_lock.own_lock());
u32 page_directory_table_index = (vaddr.get() >> 30) & 0x3;
u32 page_directory_index = (vaddr.get() >> 21) & 0x1ff;
u32 page_table_index = (vaddr.get() >> 12) & 0x1ff;
@ -181,7 +182,7 @@ const PageTableEntry* MemoryManager::pte(const PageDirectory& page_directory, Vi
PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, VirtualAddress vaddr)
{
ASSERT_INTERRUPTS_DISABLED();
ScopedSpinLock lock(s_mm_lock);
ASSERT(s_mm_lock.own_lock());
u32 page_directory_table_index = (vaddr.get() >> 30) & 0x3;
u32 page_directory_index = (vaddr.get() >> 21) & 0x1ff;
u32 page_table_index = (vaddr.get() >> 12) & 0x1ff;
@ -554,7 +555,7 @@ extern "C" PageTableEntry boot_pd3_pt1023[1024];
PageDirectoryEntry* MemoryManager::quickmap_pd(PageDirectory& directory, size_t pdpt_index)
{
ScopedSpinLock lock(s_mm_lock);
ASSERT(s_mm_lock.own_lock());
auto& pte = boot_pd3_pt1023[4];
auto pd_paddr = directory.m_directory_pages[pdpt_index]->paddr();
if (pte.physical_page_base() != pd_paddr.as_ptr()) {
@ -565,14 +566,17 @@ PageDirectoryEntry* MemoryManager::quickmap_pd(PageDirectory& directory, size_t
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
flush_tlb(VirtualAddress(0xffe04000));
// Because we must continue to hold the MM lock while we use this
// mapping, it is sufficient to only flush on the current CPU. Other
// CPUs trying to use this API must wait on the MM lock anyway
flush_tlb_local(VirtualAddress(0xffe04000));
}
return (PageDirectoryEntry*)0xffe04000;
}
PageTableEntry* MemoryManager::quickmap_pt(PhysicalAddress pt_paddr)
{
ScopedSpinLock lock(s_mm_lock);
ASSERT(s_mm_lock.own_lock());
auto& pte = boot_pd3_pt1023[0];
if (pte.physical_page_base() != pt_paddr.as_ptr()) {
#ifdef MM_DEBUG
@ -582,7 +586,10 @@ PageTableEntry* MemoryManager::quickmap_pt(PhysicalAddress pt_paddr)
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
flush_tlb(VirtualAddress(0xffe00000));
// Because we must continue to hold the MM lock while we use this
// mapping, it is sufficient to only flush on the current CPU. Other
// CPUs trying to use this API must wait on the MM lock anyway
flush_tlb_local(VirtualAddress(0xffe00000));
}
return (PageTableEntry*)0xffe00000;
}
@ -606,7 +613,7 @@ u8* MemoryManager::quickmap_page(PhysicalPage& physical_page)
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
flush_tlb_local(vaddr, 1);
flush_tlb_local(vaddr);
}
return vaddr.as_ptr();
}
@ -621,7 +628,7 @@ void MemoryManager::unquickmap_page()
VirtualAddress vaddr(0xffe00000 + pte_idx * PAGE_SIZE);
auto& pte = boot_pd3_pt1023[pte_idx];
pte.clear();
flush_tlb_local(vaddr, 1);
flush_tlb_local(vaddr);
mm_data.m_quickmap_in_use.unlock(mm_data.m_quickmap_prev_flags);
}

7
Kernel/VM/PageDirectory.cpp
View File

@ -48,7 +48,7 @@ static HashMap<u32, PageDirectory*>& cr3_map()
RefPtr<PageDirectory> PageDirectory::find_by_cr3(u32 cr3)
{
InterruptDisabler disabler;
ScopedSpinLock lock(s_mm_lock);
return cr3_map().get(cr3).value_or({});
}
@ -76,6 +76,7 @@ PageDirectory::PageDirectory()
PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_range_allocator)
: m_process(&process)
{
ScopedSpinLock lock(s_mm_lock);
if (parent_range_allocator) {
m_range_allocator.initialize_from_parent(*parent_range_allocator);
} else {
@ -93,7 +94,6 @@ PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_rang
m_directory_pages[3] = MM.kernel_page_directory().m_directory_pages[3];
{
InterruptDisabler disabler;
auto& table = *(PageDirectoryPointerTable*)MM.quickmap_page(*m_directory_table);
table.raw[0] = (u64)m_directory_pages[0]->paddr().as_ptr() | 1;
table.raw[1] = (u64)m_directory_pages[1]->paddr().as_ptr() | 1;
@ -109,7 +109,6 @@ PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_rang
auto* new_pd = MM.quickmap_pd(*this, 0);
memcpy(new_pd, &buffer, sizeof(PageDirectoryEntry));
InterruptDisabler disabler;
cr3_map().set(cr3(), this);
}
@ -118,7 +117,7 @@ PageDirectory::~PageDirectory()
#ifdef MM_DEBUG
dbg() << "MM: ~PageDirectory K" << this;
#endif
InterruptDisabler disabler;
ScopedSpinLock lock(s_mm_lock);
cr3_map().remove(cr3());
}