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https://github.com/RGBCube/serenity
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Kernel: Move kernel above the 3GB virtual address mark
The kernel and its static data structures are no longer identity-mapped in the bottom 8MB of the address space, but instead move above 3GB. The first 8MB above 3GB are pseudo-identity-mapped to the bottom 8MB of the physical address space. But things don't have to stay this way! Thanks to Jesse who made an earlier attempt at this, it was really easy to get device drivers working once the page tables were in place! :^) Fixes #734.
This commit is contained in:
Andreas Kling
parent
cee597a728
commit
e362b56b4f
17 changed files with 325 additions and 125 deletions
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@ -21,13 +21,9 @@ MemoryManager& MM
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return *s_the;
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}
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MemoryManager::MemoryManager(u32 physical_address_for_kernel_page_tables)
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MemoryManager::MemoryManager()
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{
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m_kernel_page_directory = PageDirectory::create_at_fixed_address(PhysicalAddress(physical_address_for_kernel_page_tables));
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for (size_t i = 0; i < 4; ++i) {
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m_low_page_tables[i] = (PageTableEntry*)(physical_address_for_kernel_page_tables + PAGE_SIZE * (5 + i));
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memset(m_low_page_tables[i], 0, PAGE_SIZE);
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}
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m_kernel_page_directory = PageDirectory::create_kernel_page_directory();
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initialize_paging();
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@ -49,32 +45,11 @@ void MemoryManager::initialize_paging()
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dbgprintf("MM: Kernel page directory @ %p\n", kernel_page_directory().cr3());
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#endif
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#ifdef MM_DEBUG
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dbgprintf("MM: Protect against null dereferences\n");
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#endif
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// Make null dereferences crash.
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map_protected(VirtualAddress(0), PAGE_SIZE);
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#ifdef MM_DEBUG
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dbgprintf("MM: Identity map bottom 8MB\n");
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#endif
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// The bottom 8 MB (except for the null page) are identity mapped & supervisor only.
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// Every process shares these mappings.
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create_identity_mapping(kernel_page_directory(), VirtualAddress(PAGE_SIZE), (8 * MB) - PAGE_SIZE);
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// Disable execution from 0MB through 1MB (BIOS data, legacy things, ...)
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if (g_cpu_supports_nx) {
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for (size_t i = 0; i < (1 * MB); i += PAGE_SIZE) {
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auto& pte = ensure_pte(kernel_page_directory(), VirtualAddress(i));
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pte.set_execute_disabled(true);
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}
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// Disable execution from 2MB through 8MB (kmalloc, kmalloc_eternal, slabs, page tables, ...)
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for (size_t i = 1; i < 4; ++i) {
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auto& pte = kernel_page_directory().table().directory(0)[i];
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pte.set_execute_disabled(true);
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}
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}
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// Disable execution from 0MB through 2MB (BIOS data, legacy things, ...)
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if (g_cpu_supports_nx)
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quickmap_pd(kernel_page_directory(), 0)[0].set_execute_disabled(true);
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#if 0
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// Disable writing to the kernel text and rodata segments.
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extern u32 start_of_kernel_text;
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extern u32 start_of_kernel_data;
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@ -91,17 +66,7 @@ void MemoryManager::initialize_paging()
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pte.set_execute_disabled(true);
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}
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}
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// FIXME: We should move everything kernel-related above the 0xc0000000 virtual mark.
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// Basic physical memory map:
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// 0 -> 1 MB We're just leaving this alone for now.
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// 1 -> 2 MB Kernel image.
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// (last page before 2MB) Used by quickmap_page().
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// 2 MB -> 4 MB kmalloc_eternal() space.
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// 4 MB -> 7 MB kmalloc() space.
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// 7 MB -> 8 MB Supervisor physical pages (available for allocation!)
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// 8 MB -> MAX Userspace physical pages (available for allocation!)
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#endif
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// Basic virtual memory map:
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// 0 -> 4 KB Null page (so nullptr dereferences crash!)
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@ -109,15 +74,16 @@ void MemoryManager::initialize_paging()
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// 8 MB -> 3 GB Available to userspace.
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// 3GB -> 4 GB Kernel-only virtual address space (>0xc0000000)
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m_quickmap_addr = VirtualAddress(0xffe00000);
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#ifdef MM_DEBUG
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dbgprintf("MM: Quickmap will use %p\n", m_quickmap_addr.get());
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#endif
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m_quickmap_addr = VirtualAddress((2 * MB) - PAGE_SIZE);
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RefPtr<PhysicalRegion> region;
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bool region_is_super = false;
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for (auto* mmap = (multiboot_memory_map_t*)multiboot_info_ptr->mmap_addr; (unsigned long)mmap < multiboot_info_ptr->mmap_addr + multiboot_info_ptr->mmap_length; mmap = (multiboot_memory_map_t*)((unsigned long)mmap + mmap->size + sizeof(mmap->size))) {
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auto* mmap = (multiboot_memory_map_t*)(0xc0000000 + multiboot_info_ptr->mmap_addr);
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for (; (unsigned long)mmap < (0xc0000000 + multiboot_info_ptr->mmap_addr) + (multiboot_info_ptr->mmap_length); mmap = (multiboot_memory_map_t*)((unsigned long)mmap + mmap->size + sizeof(mmap->size))) {
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kprintf("MM: Multiboot mmap: base_addr = 0x%x%08x, length = 0x%x%08x, type = 0x%x\n",
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(u32)(mmap->addr >> 32),
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(u32)(mmap->addr & 0xffffffff),
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@ -221,6 +187,7 @@ void MemoryManager::initialize_paging()
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if (g_cpu_supports_smap) {
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// Turn on CR4.SMAP
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kprintf("x86: Enabling SMAP\n");
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asm volatile(
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"mov %cr4, %eax\n"
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"orl $0x200000, %eax\n"
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@ -261,18 +228,14 @@ PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, Virtual
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u32 page_directory_index = (vaddr.get() >> 21) & 0x1ff;
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u32 page_table_index = (vaddr.get() >> 12) & 0x1ff;
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PageDirectoryEntry& pde = page_directory.table().directory(page_directory_table_index)[page_directory_index];
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auto* pd = quickmap_pd(page_directory, page_directory_table_index);
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PageDirectoryEntry& pde = pd[page_directory_index];
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if (!pde.is_present()) {
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#ifdef MM_DEBUG
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dbgprintf("MM: PDE %u not present (requested for V%p), allocating\n", page_directory_index, vaddr.get());
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#endif
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if (page_directory_table_index == 0 && page_directory_index < 4) {
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ASSERT(&page_directory == m_kernel_page_directory);
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pde.set_page_table_base((u32)m_low_page_tables[page_directory_index]);
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pde.set_user_allowed(false);
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pde.set_present(true);
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pde.set_writable(true);
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pde.set_global(true);
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if (page_directory_table_index == 3 && page_directory_index < 4) {
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ASSERT_NOT_REACHED();
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} else {
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auto page_table = allocate_supervisor_physical_page();
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#ifdef MM_DEBUG
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@ -292,7 +255,13 @@ PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, Virtual
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page_directory.m_physical_pages.set(page_directory_index, move(page_table));
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}
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}
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return pde.page_table_base()[page_table_index];
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//if (&page_directory != &kernel_page_directory() && page_directory_table_index != 3) {
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return quickmap_pt(PhysicalAddress((u32)pde.page_table_base()))[page_table_index];
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//}
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auto* phys_ptr = &pde.page_table_base()[page_table_index];
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return *(PageTableEntry*)((u8*)phys_ptr + 0xc0000000);
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}
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void MemoryManager::map_protected(VirtualAddress vaddr, size_t length)
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@ -325,9 +294,9 @@ void MemoryManager::create_identity_mapping(PageDirectory& page_directory, Virtu
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}
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}
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void MemoryManager::initialize(u32 physical_address_for_kernel_page_tables)
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void MemoryManager::initialize()
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{
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s_the = new MemoryManager(physical_address_for_kernel_page_tables);
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s_the = new MemoryManager;
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}
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Region* MemoryManager::kernel_region_from_vaddr(VirtualAddress vaddr)
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@ -349,6 +318,29 @@ Region* MemoryManager::user_region_from_vaddr(Process& process, VirtualAddress v
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return ®ion;
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}
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dbg() << process << " Couldn't find user region for " << vaddr;
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if (auto* kreg = kernel_region_from_vaddr(vaddr)) {
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dbg() << process << " OTOH, there is a kernel region: " << kreg->range() << ": " << kreg->name();
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} else {
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dbg() << process << " AND no kernel region either";
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}
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process.dump_regions();
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kprintf("Kernel regions:\n");
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kprintf("BEGIN END SIZE ACCESS NAME\n");
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for (auto& region : MM.m_kernel_regions) {
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kprintf("%08x -- %08x %08x %c%c%c%c%c%c %s\n",
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region.vaddr().get(),
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region.vaddr().offset(region.size() - 1).get(),
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region.size(),
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region.is_readable() ? 'R' : ' ',
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region.is_writable() ? 'W' : ' ',
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region.is_executable() ? 'X' : ' ',
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region.is_shared() ? 'S' : ' ',
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region.is_stack() ? 'T' : ' ',
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region.vmobject().is_purgeable() ? 'P' : ' ',
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region.name().characters());
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}
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return nullptr;
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}
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@ -567,7 +559,7 @@ RefPtr<PhysicalPage> MemoryManager::allocate_supervisor_physical_page()
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dbgprintf("MM: allocate_supervisor_physical_page vending P%p\n", page->paddr().get());
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#endif
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fast_u32_fill((u32*)page->paddr().as_ptr(), 0, PAGE_SIZE / sizeof(u32));
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fast_u32_fill((u32*)page->paddr().offset(0xc0000000).as_ptr(), 0, PAGE_SIZE / sizeof(u32));
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++m_super_physical_pages_used;
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return page;
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}
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@ -601,6 +593,37 @@ void MemoryManager::flush_tlb(VirtualAddress vaddr)
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: "memory");
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}
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extern "C" PageTableEntry boot_pd3_pde1023_pt[1024];
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PageDirectoryEntry* MemoryManager::quickmap_pd(PageDirectory& directory, size_t pdpt_index)
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{
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auto& pte = boot_pd3_pde1023_pt[4];
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auto pd_paddr = directory.m_directory_pages[pdpt_index]->paddr();
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if (pte.physical_page_base() != pd_paddr.as_ptr()) {
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//dbgprintf("quickmap_pd: Mapping P%p at 0xffe04000 in pte @ %p\n", directory.m_directory_pages[pdpt_index]->paddr().as_ptr(), &pte);
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pte.set_physical_page_base(pd_paddr.get());
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pte.set_present(true);
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pte.set_writable(true);
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pte.set_user_allowed(false);
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flush_tlb(VirtualAddress(0xffe04000));
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}
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return (PageDirectoryEntry*)0xffe04000;
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}
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PageTableEntry* MemoryManager::quickmap_pt(PhysicalAddress pt_paddr)
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{
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auto& pte = boot_pd3_pde1023_pt[8];
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if (pte.physical_page_base() != pt_paddr.as_ptr()) {
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//dbgprintf("quickmap_pt: Mapping P%p at 0xffe08000 in pte @ %p\n", pt_paddr.as_ptr(), &pte);
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pte.set_physical_page_base(pt_paddr.get());
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pte.set_present(true);
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pte.set_writable(true);
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pte.set_user_allowed(false);
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flush_tlb(VirtualAddress(0xffe08000));
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}
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return (PageTableEntry*)0xffe08000;
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}
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void MemoryManager::map_for_kernel(VirtualAddress vaddr, PhysicalAddress paddr, bool cache_disabled)
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{
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auto& pte = ensure_pte(kernel_page_directory(), vaddr);
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@ -20,6 +20,28 @@
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#define PAGE_ROUND_UP(x) ((((u32)(x)) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1)))
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template<typename T>
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inline T* low_physical_to_virtual(T* physical)
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{
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return (T*)(((u8*)physical) + 0xc0000000);
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}
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inline u32 low_physical_to_virtual(u32 physical)
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{
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return physical + 0xc0000000;
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}
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template<typename T>
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inline T* virtual_to_low_physical(T* physical)
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{
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return (T*)(((u8*)physical) - 0xc0000000);
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}
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inline u32 virtual_to_low_physical(u32 physical)
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{
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return physical - 0xc0000000;
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}
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class KBuffer;
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class SynthFSInode;
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@ -38,7 +60,7 @@ class MemoryManager {
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public:
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static MemoryManager& the();
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static void initialize(u32 physical_address_for_kernel_page_tables);
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static void initialize();
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PageFaultResponse handle_page_fault(const PageFault&);
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@ -85,7 +107,7 @@ public:
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static const Region* region_from_vaddr(const Process&, VirtualAddress);
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private:
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MemoryManager(u32 physical_address_for_kernel_page_tables);
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MemoryManager();
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~MemoryManager();
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enum class AccessSpace { Kernel, User };
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@ -116,6 +138,9 @@ private:
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u8* quickmap_page(PhysicalPage&);
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void unquickmap_page();
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PageDirectoryEntry* quickmap_pd(PageDirectory&, size_t pdpt_index);
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PageTableEntry* quickmap_pt(PhysicalAddress);
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PageDirectory& kernel_page_directory() { return *m_kernel_page_directory; }
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PageTableEntry& ensure_pte(PageDirectory&, VirtualAddress);
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@ -4,7 +4,7 @@
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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 = 0xc0000000;
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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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@ -21,22 +21,23 @@ RefPtr<PageDirectory> PageDirectory::find_by_cr3(u32 cr3)
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return cr3_map().get(cr3).value_or({});
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}
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PageDirectory::PageDirectory(PhysicalAddress paddr)
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: m_range_allocator(VirtualAddress(0xc0000000), 0x3f000000)
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extern "C" u32 boot_pdpt;
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extern "C" u32 boot_pd0;
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extern "C" u32 boot_pd3;
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PageDirectory::PageDirectory()
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: m_range_allocator(VirtualAddress(0xc0c00000), 0x3f000000)
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{
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m_directory_table = PhysicalPage::create(paddr, true, false);
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m_directory_pages[0] = PhysicalPage::create(paddr.offset(PAGE_SIZE * 1), true, false);
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m_directory_pages[1] = PhysicalPage::create(paddr.offset(PAGE_SIZE * 2), true, false);
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m_directory_pages[2] = PhysicalPage::create(paddr.offset(PAGE_SIZE * 3), true, false);
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m_directory_pages[3] = PhysicalPage::create(paddr.offset(PAGE_SIZE * 4), true, false);
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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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InterruptDisabler disabler;
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cr3_map().set(cr3(), this);
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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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@ -44,7 +45,6 @@ PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_rang
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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_supervisor_physical_page();
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m_directory_pages[1] = MM.allocate_supervisor_physical_page();
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@ -58,10 +58,11 @@ PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_rang
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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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table().directory(0)[0].copy_from({}, MM.kernel_page_directory().table().directory(0)[0]);
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table().directory(0)[1].copy_from({}, MM.kernel_page_directory().table().directory(0)[1]);
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table().directory(0)[2].copy_from({}, MM.kernel_page_directory().table().directory(0)[2]);
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table().directory(0)[3].copy_from({}, MM.kernel_page_directory().table().directory(0)[3]);
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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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@ -74,4 +75,4 @@ PageDirectory::~PageDirectory()
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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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}
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@ -16,13 +16,13 @@ public:
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{
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return adopt(*new PageDirectory(process, parent_range_allocator));
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}
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static NonnullRefPtr<PageDirectory> create_at_fixed_address(PhysicalAddress paddr) { return adopt(*new PageDirectory(paddr)); }
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static NonnullRefPtr<PageDirectory> create_kernel_page_directory() { return adopt(*new PageDirectory); }
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static RefPtr<PageDirectory> find_by_cr3(u32);
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~PageDirectory();
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u32 cr3() const { return m_directory_table->paddr().get(); }
|
||||
PageDirectoryPointerTable& table() { return *reinterpret_cast<PageDirectoryPointerTable*>(cr3()); }
|
||||
PageDirectoryPointerTable& table() { return *reinterpret_cast<PageDirectoryPointerTable*>(0xc0000000 + cr3()); }
|
||||
|
||||
RangeAllocator& range_allocator() { return m_range_allocator; }
|
||||
|
||||
|
|
@ -31,7 +31,7 @@ public:
|
|||
|
||||
private:
|
||||
PageDirectory(Process&, const RangeAllocator* parent_range_allocator);
|
||||
explicit PageDirectory(PhysicalAddress);
|
||||
PageDirectory();
|
||||
|
||||
Process* m_process { nullptr };
|
||||
RangeAllocator m_range_allocator;
|
||||
|
|
|
|||
|
|
@ -242,7 +242,7 @@ void Region::map_individual_page_impl(size_t page_index)
|
|||
pte.set_execute_disabled(!is_executable());
|
||||
pte.set_user_allowed(is_user_accessible());
|
||||
#ifdef MM_DEBUG
|
||||
dbg() << "MM: >> region map (PD=" << m_page_directory->cr3() << ", PTE=" << (void*)pte.raw() << "{" << &pte << "}) " << name() << " " << page_vaddr << " => " << physical_page->paddr() << " (@" << physical_page.ptr() << ")";
|
||||
dbg() << "MM: >> region map (PD=" << m_page_directory->cr3() << ", PTE=" << (void*)pte.raw() << "{" << &pte << "}) " << name() << " " << page_vaddr << " => " << physical_page->paddr() << " (@" << physical_page.ptr() << ")";
|
||||
#endif
|
||||
}
|
||||
MM.flush_tlb(page_vaddr);
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue