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https://github.com/RGBCube/serenity
synced 2025-07-25 19:37:35 +00:00
Refactor the virtual memory object model a bit:
Process now has a number of Regions. Each Region is backed by a VMObject. A VMObject can be file-backed or anonymous. These can be shared.
This commit is contained in:
Andreas Kling
parent
3c8064a787
commit
862f108cb5
6 changed files with 165 additions and 31 deletions
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@ -5,6 +5,7 @@
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#include "i386.h"
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#include "StdLib.h"
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#include "Process.h"
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#include <LibC/errno_numbers.h>
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//#define MM_DEBUG
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//#define PAGE_FAULT_DEBUG
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@ -226,7 +227,8 @@ Region* MemoryManager::region_from_laddr(Process& process, LinearAddress laddr)
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bool MemoryManager::copy_on_write(Process& process, Region& region, unsigned page_index_in_region)
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{
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ASSERT_INTERRUPTS_DISABLED();
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if (region.physical_pages[page_index_in_region]->retain_count() == 1) {
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auto& vmo = region.vmo();
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if (vmo.physical_pages()[page_index_in_region]->retain_count() == 1) {
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf(" >> It's a COW page but nobody is sharing it anymore. Remap r/w\n");
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#endif
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@ -238,7 +240,7 @@ bool MemoryManager::copy_on_write(Process& process, Region& region, unsigned pag
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf(" >> It's a COW page and it's time to COW!\n");
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#endif
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auto physical_page_to_copy = move(region.physical_pages[page_index_in_region]);
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auto physical_page_to_copy = move(vmo.physical_pages()[page_index_in_region]);
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auto ppages = allocate_physical_pages(1);
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ASSERT(ppages.size() == 1);
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byte* dest_ptr = quickmap_page(*ppages[0]);
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@ -247,7 +249,7 @@ bool MemoryManager::copy_on_write(Process& process, Region& region, unsigned pag
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dbgprintf(" >> COW P%x <- P%x\n", ppages[0]->paddr().get(), physical_page_to_copy->paddr().get());
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#endif
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memcpy(dest_ptr, src_ptr, PAGE_SIZE);
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region.physical_pages[page_index_in_region] = move(ppages[0]);
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vmo.physical_pages()[page_index_in_region] = move(ppages[0]);
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unquickmap_page();
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region.cow_map.set(page_index_in_region, false);
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remap_region_page(process.m_page_directory, region, page_index_in_region, true);
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@ -256,9 +258,13 @@ bool MemoryManager::copy_on_write(Process& process, Region& region, unsigned pag
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bool MemoryManager::page_in_from_vnode(Process& process, Region& region, unsigned page_index_in_region)
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{
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ASSERT(region.physical_pages[page_index_in_region].is_null());
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region.physical_pages[page_index_in_region] = allocate_physical_page();
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if (region.physical_pages[page_index_in_region].is_null()) {
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auto& vmo = region.vmo();
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ASSERT(!vmo.is_anonymous());
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ASSERT(vmo.vnode());
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auto& vnode = *vmo.vnode();
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ASSERT(vmo.physical_pages()[page_index_in_region].is_null());
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vmo.physical_pages()[page_index_in_region] = allocate_physical_page();
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if (vmo.physical_pages()[page_index_in_region].is_null()) {
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kprintf("MM: page_in_from_vnode was unable to allocate a physical page\n");
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return false;
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}
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@ -266,7 +272,7 @@ bool MemoryManager::page_in_from_vnode(Process& process, Region& region, unsigne
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byte* dest_ptr = region.linearAddress.offset(page_index_in_region * PAGE_SIZE).asPtr();
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dbgprintf("MM: page_in_from_vnode ready to read from vnode, will write to L%x!\n", dest_ptr);
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sti(); // Oh god here we go...
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auto nread = region.m_vnode->fileSystem()->readInodeBytes(region.m_vnode->inode, region.m_file_offset, PAGE_SIZE, dest_ptr, nullptr);
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auto nread = vnode.fileSystem()->readInodeBytes(vnode.inode, vmo.vnode_offset(), PAGE_SIZE, dest_ptr, nullptr);
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if (nread < 0) {
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kprintf("MM: page_in_form_vnode had error (%d) while reading!\n", nread);
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return false;
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@ -289,7 +295,7 @@ PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
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ASSERT(region);
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auto page_index_in_region = region->page_index_from_address(fault.laddr());
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if (fault.is_not_present()) {
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if (region->m_vnode) {
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if (region->vmo().vnode()) {
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dbgprintf("NP(vnode) fault in Region{%p}[%u]\n", region, page_index_in_region);
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page_in_from_vnode(*current, *region, page_index_in_region);
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return PageFaultResponse::Continue;
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@ -407,7 +413,7 @@ void MemoryManager::remap_region_page(PageDirectory* page_directory, Region& reg
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InterruptDisabler disabler;
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auto page_laddr = region.linearAddress.offset(page_index_in_region * PAGE_SIZE);
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auto pte = ensurePTE(page_directory, page_laddr);
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auto& physical_page = region.physical_pages[page_index_in_region];
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auto& physical_page = region.vmo().physical_pages()[page_index_in_region];
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ASSERT(physical_page);
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pte.setPhysicalPageBase(physical_page->paddr().get());
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pte.setPresent(true); // FIXME: Maybe we should use the is_readable flag here?
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@ -431,10 +437,11 @@ void MemoryManager::remap_region(Process& process, Region& region)
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void MemoryManager::map_region_at_address(PageDirectory* page_directory, Region& region, LinearAddress laddr, bool user_allowed)
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{
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InterruptDisabler disabler;
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for (size_t i = 0; i < region.physical_pages.size(); ++i) {
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auto& vmo = region.vmo();
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for (size_t i = 0; i < vmo.page_count(); ++i) {
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auto page_laddr = laddr.offset(i * PAGE_SIZE);
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auto pte = ensurePTE(page_directory, page_laddr);
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auto& physical_page = region.physical_pages[i];
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auto& physical_page = vmo.physical_pages()[i];
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if (physical_page) {
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pte.setPhysicalPageBase(physical_page->paddr().get());
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pte.setPresent(true); // FIXME: Maybe we should use the is_readable flag here?
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@ -510,7 +517,8 @@ void MemoryManager::remove_kernel_alias_for_region(Region& region, byte* addr)
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bool MemoryManager::unmapRegion(Process& process, Region& region)
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{
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InterruptDisabler disabler;
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for (size_t i = 0; i < region.physical_pages.size(); ++i) {
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auto& vmo = region.vmo();
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for (size_t i = 0; i < vmo.page_count(); ++i) {
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auto laddr = region.linearAddress.offset(i * PAGE_SIZE);
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auto pte = ensurePTE(process.m_page_directory, laddr);
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pte.setPhysicalPageBase(0);
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@ -519,7 +527,7 @@ bool MemoryManager::unmapRegion(Process& process, Region& region)
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pte.setUserAllowed(false);
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flushTLB(laddr);
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#ifdef MM_DEBUG
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auto& physical_page = region.physical_pages[i];
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auto& physical_page = vmo.physical_pages()[i];
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dbgprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, physical_page ? physical_page->paddr().get() : 0);
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#endif
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}
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@ -569,26 +577,51 @@ RetainPtr<Region> Region::clone()
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InterruptDisabler disabler;
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if (is_readable && !is_writable) {
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// Create a new region backed by the same physical pages.
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return adopt(*new Region(linearAddress, size, physical_pages, String(name), is_readable, is_writable));
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// Create a new region backed by the same VMObject.
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return adopt(*new Region(linearAddress, size, m_vmo.copyRef(), String(name), is_readable, is_writable));
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}
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// Set up a COW region. The parent (this) region becomes COW as well!
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for (size_t i = 0; i < physical_pages.size(); ++i)
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for (size_t i = 0; i < vmo().page_count(); ++i)
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cow_map.set(i, true);
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MM.remap_region(*current, *this);
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return adopt(*new Region(linearAddress, size, physical_pages, String(name), is_readable, is_writable, true));
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return adopt(*new Region(linearAddress, size, m_vmo->clone(), String(name), is_readable, is_writable, true));
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}
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Region::Region(LinearAddress a, size_t s, Vector<RetainPtr<PhysicalPage>> pp, String&& n, bool r, bool w, bool cow)
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Region::Region(LinearAddress a, size_t s, String&& n, bool r, bool w, bool cow)
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: linearAddress(a)
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, size(s)
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, physical_pages(move(pp))
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, m_vmo(VMObject::create_anonymous(s))
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, name(move(n))
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, is_readable(r)
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, is_writable(w)
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, cow_map(Bitmap::create(physical_pages.size(), cow))
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, cow_map(Bitmap::create(m_vmo->page_count(), cow))
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{
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m_vmo->set_name(name);
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}
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Region::Region(LinearAddress a, size_t s, RetainPtr<VirtualFileSystem::Node>&& vnode, String&& n, bool r, bool w)
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: linearAddress(a)
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, size(s)
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, m_vmo(VMObject::create_file_backed(move(vnode), s))
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, name(move(n))
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, is_readable(r)
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, is_writable(w)
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, cow_map(Bitmap::create(m_vmo->page_count()))
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{
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m_vmo->set_name(name);
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}
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Region::Region(LinearAddress a, size_t s, RetainPtr<VMObject>&& vmo, String&& n, bool r, bool w, bool cow)
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: linearAddress(a)
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, size(s)
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, m_vmo(move(vmo))
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, name(move(n))
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, is_readable(r)
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, is_writable(w)
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, cow_map(Bitmap::create(m_vmo->page_count(), cow))
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{
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m_vmo->set_name(name);
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}
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Region::~Region()
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@ -604,3 +637,66 @@ void PhysicalPage::return_to_freelist()
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dbgprintf("MM: P%x released to freelist\n", m_paddr.get());
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#endif
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}
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RetainPtr<VMObject> VMObject::create_file_backed(RetainPtr<VirtualFileSystem::Node>&& vnode, size_t size)
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{
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return adopt(*new VMObject(move(vnode), size));
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}
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RetainPtr<VMObject> VMObject::create_anonymous(size_t size)
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{
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return adopt(*new VMObject(size));
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}
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RetainPtr<VMObject> VMObject::clone()
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{
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return adopt(*new VMObject(*this));
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}
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VMObject::VMObject(VMObject& other)
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: m_name(other.m_name)
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, m_anonymous(other.m_anonymous)
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, m_vnode_offset(other.m_vnode_offset)
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, m_size(other.m_size)
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, m_vnode(other.m_vnode)
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, m_physical_pages(other.m_physical_pages)
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{
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}
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VMObject::VMObject(size_t size)
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: m_anonymous(true)
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, m_size(size)
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{
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m_physical_pages.resize(page_count());
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}
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VMObject::VMObject(RetainPtr<VirtualFileSystem::Node>&& vnode, size_t size)
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: m_size(size)
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, m_vnode(move(vnode))
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{
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m_physical_pages.resize(page_count());
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}
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VMObject::~VMObject()
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{
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}
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int Region::commit(Process& process)
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{
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InterruptDisabler disabler;
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#ifdef MM_DEBUG
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dbgprintf("MM: commit %u pages in at L%x\n", vmo().page_count(), linearAddress.get());
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#endif
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for (size_t i = 0; i < vmo().page_count(); ++i) {
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if (!vmo().physical_pages()[i].is_null())
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continue;
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auto physical_page = MM.allocate_physical_page();
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if (!physical_page) {
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kprintf("MM: page_in_from_vnode was unable to allocate a physical page\n");
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return -ENOMEM;
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}
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vmo().physical_pages()[i] = move(physical_page);
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MM.remap_region_page(process.m_page_directory, *this, i, true);
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}
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return 0;
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}
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