mirror of
https://github.com/RGBCube/serenity
synced 2025-05-28 04:55:09 +00:00
ad1f79fb4a
We now use the regular "user" physical pages for on-demand page table allocations. This was by far the biggest source of super physical page exhaustion, so that bug should be a thing of the past now. :^) We still have super pages, but they are barely used. They remain useful for code that requires memory with a low physical address. Fixes #1000.
78 lines
3.1 KiB
C++
78 lines
3.1 KiB
C++
#include <Kernel/Process.h>
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#include <Kernel/Thread.h>
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#include <Kernel/VM/MemoryManager.h>
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#include <Kernel/VM/PageDirectory.h>
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static const u32 userspace_range_base = 0x01000000;
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static const u32 kernelspace_range_base = 0xc0800000;
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static HashMap<u32, PageDirectory*>& cr3_map()
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{
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ASSERT_INTERRUPTS_DISABLED();
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static HashMap<u32, PageDirectory*>* map;
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if (!map)
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map = new HashMap<u32, PageDirectory*>;
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return *map;
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}
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RefPtr<PageDirectory> PageDirectory::find_by_cr3(u32 cr3)
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{
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InterruptDisabler disabler;
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return cr3_map().get(cr3).value_or({});
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}
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extern "C" PageDirectoryEntry* boot_pdpt[4];
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extern "C" PageDirectoryEntry boot_pd0[1024];
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extern "C" PageDirectoryEntry boot_pd3[1024];
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PageDirectory::PageDirectory()
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: m_range_allocator(VirtualAddress(0xc0c00000), 0x3f000000)
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{
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// Adopt the page tables already set up by boot.S
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PhysicalAddress boot_pdpt_paddr(virtual_to_low_physical((u32)boot_pdpt));
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PhysicalAddress boot_pd0_paddr(virtual_to_low_physical((u32)boot_pd0));
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PhysicalAddress boot_pd3_paddr(virtual_to_low_physical((u32)boot_pd3));
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kprintf("MM: boot_pdpt @ P%p\n", boot_pdpt_paddr.get());
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kprintf("MM: boot_pd0 @ P%p\n", boot_pd0_paddr.get());
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kprintf("MM: boot_pd3 @ P%p\n", boot_pd3_paddr.get());
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m_directory_table = PhysicalPage::create(boot_pdpt_paddr, true, false);
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m_directory_pages[0] = PhysicalPage::create(boot_pd0_paddr, true, false);
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m_directory_pages[3] = PhysicalPage::create(boot_pd3_paddr, true, false);
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}
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PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_range_allocator)
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: m_process(&process)
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, m_range_allocator(parent_range_allocator ? RangeAllocator(*parent_range_allocator) : RangeAllocator(VirtualAddress(userspace_range_base), kernelspace_range_base - userspace_range_base))
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{
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// Set up a userspace page directory
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m_directory_table = MM.allocate_supervisor_physical_page();
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m_directory_pages[0] = MM.allocate_user_physical_page();
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m_directory_pages[1] = MM.allocate_user_physical_page();
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m_directory_pages[2] = MM.allocate_user_physical_page();
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// Share the top 1 GB of kernel-only mappings (>=3GB or >=0xc0000000)
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m_directory_pages[3] = MM.kernel_page_directory().m_directory_pages[3];
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table().raw[0] = (u64)m_directory_pages[0]->paddr().as_ptr() | 1;
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table().raw[1] = (u64)m_directory_pages[1]->paddr().as_ptr() | 1;
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table().raw[2] = (u64)m_directory_pages[2]->paddr().as_ptr() | 1;
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table().raw[3] = (u64)m_directory_pages[3]->paddr().as_ptr() | 1;
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// Clone bottom 8 MB of mappings from kernel_page_directory
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PageDirectoryEntry buffer[4];
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auto* kernel_pd = MM.quickmap_pd(MM.kernel_page_directory(), 0);
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memcpy(buffer, kernel_pd, sizeof(PageDirectoryEntry) * 4);
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auto* new_pd = MM.quickmap_pd(*this, 0);
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memcpy(new_pd, buffer, sizeof(PageDirectoryEntry) * 4);
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InterruptDisabler disabler;
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cr3_map().set(cr3(), this);
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}
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PageDirectory::~PageDirectory()
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{
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#ifdef MM_DEBUG
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dbgprintf("MM: ~PageDirectory K%x\n", this);
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#endif
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InterruptDisabler disabler;
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cr3_map().remove(cr3());
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}
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