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Kernel: Add Region helpers for accessing underlying physical pages

Browse source 
Since a Region is basically a view into a potentially larger VMObject,
it was always necessary to include the Region starting offset when
accessing its underlying physical pages.

Until now, you had to do that manually, but this patch adds a simple
Region::physical_page() for read-only access and a physical_page_slot()
when you want a mutable reference to the RefPtr<PhysicalPage> itself.

A lot of code is simplified by making use of this.
This commit is contained in:
Andreas Kling 2020-04-28 16:19:50 +02:00
parent 8a417c311f
commit 9c856811b2
Notes: sideshowbarker 2024-07-19 07:13:18 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/9c856811b2a
8 changed files with 64 additions and 48 deletions
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2
Kernel/Devices/SB16.cpp
View file

@ -179,7 +179,7 @@ ssize_t SB16::read(FileDescription&, size_t, u8*, ssize_t)
void SB16::dma_start(uint32_t length)
{
const auto addr = m_dma_region->vmobject().physical_pages()[0]->paddr().get();
const auto addr = m_dma_region->physical_page(0)->paddr().get();
const u8 channel = 5; // 16-bit samples use DMA channel 5 (on the master DMA controller)
const u8 mode = 0;

7
Kernel/FileSystem/ProcFS.cpp
View file

@ -319,11 +319,10 @@ Optional<KBuffer> procfs$pid_vm(InodeIdentifier identifier)
StringBuilder pagemap_builder;
for (size_t i = 0; i < region.page_count(); ++i) {
auto page_index = region.first_page_index() + i;
auto& physical_page_slot = region.vmobject().physical_pages()[page_index];
if (!physical_page_slot)
auto* page = region.physical_page(i);
if (!page)
pagemap_builder.append('N');
else if (physical_page_slot == MM.shared_zero_page())
else if (page->is_shared_zero_page())
pagemap_builder.append('Z');
else
pagemap_builder.append('P');

20
Kernel/Net/E1000NetworkAdapter.cpp
View file

@ -279,12 +279,14 @@ void E1000NetworkAdapter::initialize_rx_descriptors()
auto* rx_descriptors = (e1000_tx_desc*)m_rx_descriptors_region->vaddr().as_ptr();
for (int i = 0; i < number_of_rx_descriptors; ++i) {
auto& descriptor = rx_descriptors[i];
m_rx_buffers_regions.append(MM.allocate_contiguous_kernel_region(PAGE_ROUND_UP(8192), "E1000 RX buffer", Region::Access::Read | Region::Access::Write));
descriptor.addr = m_rx_buffers_regions[i]->vmobject().physical_pages()[0]->paddr().get();
auto region = MM.allocate_contiguous_kernel_region(8192, "E1000 RX buffer", Region::Access::Read | Region::Access::Write);
ASSERT(region);
m_rx_buffers_regions.append(region.release_nonnull());
descriptor.addr = m_rx_buffers_regions[i].physical_page(0)->paddr().get();
descriptor.status = 0;
}
out32(REG_RXDESCLO, m_rx_descriptors_region->vmobject().physical_pages()[0]->paddr().get());
out32(REG_RXDESCLO, m_rx_descriptors_region->physical_page(0)->paddr().get());
out32(REG_RXDESCHI, 0);
out32(REG_RXDESCLEN, number_of_rx_descriptors * sizeof(e1000_rx_desc));
out32(REG_RXDESCHEAD, 0);
@ -298,12 +300,14 @@ void E1000NetworkAdapter::initialize_tx_descriptors()
auto* tx_descriptors = (e1000_tx_desc*)m_tx_descriptors_region->vaddr().as_ptr();
for (int i = 0; i < number_of_tx_descriptors; ++i) {
auto& descriptor = tx_descriptors[i];
m_tx_buffers_regions.append(MM.allocate_contiguous_kernel_region(PAGE_ROUND_UP(8192), "E1000 TX buffer", Region::Access::Read | Region::Access::Write));
descriptor.addr = m_tx_buffers_regions[i]->vmobject().physical_pages()[0]->paddr().get();
auto region = MM.allocate_contiguous_kernel_region(8192, "E1000 TX buffer", Region::Access::Read | Region::Access::Write);
ASSERT(region);
m_tx_buffers_regions.append(region.release_nonnull());
descriptor.addr = m_tx_buffers_regions[i].physical_page(0)->paddr().get();
descriptor.cmd = 0;
}
out32(REG_TXDESCLO, m_tx_descriptors_region->vmobject().physical_pages()[0]->paddr().get());
out32(REG_TXDESCLO, m_tx_descriptors_region->physical_page(0)->paddr().get());
out32(REG_TXDESCHI, 0);
out32(REG_TXDESCLEN, number_of_tx_descriptors * sizeof(e1000_tx_desc));
out32(REG_TXDESCHEAD, 0);
@ -392,7 +396,7 @@ void E1000NetworkAdapter::send_raw(const u8* data, size_t length)
auto* tx_descriptors = (e1000_tx_desc*)m_tx_descriptors_region->vaddr().as_ptr();
auto& descriptor = tx_descriptors[tx_current];
ASSERT(length <= 8192);
auto* vptr = (void*)m_tx_buffers_regions[tx_current]->vaddr().as_ptr();
auto* vptr = (void*)m_tx_buffers_regions[tx_current].vaddr().as_ptr();
memcpy(vptr, data, length);
descriptor.length = length;
descriptor.status = 0;
@ -427,7 +431,7 @@ void E1000NetworkAdapter::receive()
rx_current = (rx_current + 1) % number_of_rx_descriptors;
if (!(rx_descriptors[rx_current].status & 1))
break;
auto* buffer = m_rx_buffers_regions[rx_current]->vaddr().as_ptr();
auto* buffer = m_rx_buffers_regions[rx_current].vaddr().as_ptr();
u16 length = rx_descriptors[rx_current].length;
#ifdef E1000_DEBUG
klog() << "E1000: Received 1 packet @ " << buffer << " (" << length << ") bytes!";

5
Kernel/Net/E1000NetworkAdapter.h
View file

@ -26,6 +26,7 @@
#pragma once
#include <AK/NonnullOwnPtrVector.h>
#include <AK/OwnPtr.h>
#include <Kernel/Interrupts/IRQHandler.h>
#include <Kernel/Net/NetworkAdapter.h>
@ -96,8 +97,8 @@ private:
VirtualAddress m_mmio_base;
OwnPtr<Region> m_rx_descriptors_region;
OwnPtr<Region> m_tx_descriptors_region;
Vector<OwnPtr<Region>> m_rx_buffers_regions;
Vector<OwnPtr<Region>> m_tx_buffers_regions;
NonnullOwnPtrVector<Region> m_rx_buffers_regions;
NonnullOwnPtrVector<Region> m_tx_buffers_regions;
OwnPtr<Region> m_mmio_region;
u8 m_interrupt_line { 0 };
bool m_has_eeprom { false };

8
Kernel/Net/RTL8139NetworkAdapter.cpp
View file

@ -158,11 +158,11 @@ RTL8139NetworkAdapter::RTL8139NetworkAdapter(PCI::Address address, u8 irq)
// we add space to account for overhang from the last packet - the rtl8139
// can optionally guarantee that packets will be contiguous by
// purposefully overrunning the rx buffer
klog() << "RTL8139: RX buffer: " << m_rx_buffer->vmobject().physical_pages()[0]->paddr();
klog() << "RTL8139: RX buffer: " << m_rx_buffer->physical_page(0)->paddr();
for (int i = 0; i < RTL8139_TX_BUFFER_COUNT; i++) {
m_tx_buffers.append(MM.allocate_contiguous_kernel_region(PAGE_ROUND_UP(TX_BUFFER_SIZE), "RTL8139 TX", Region::Access::Write | Region::Access::Read));
klog() << "RTL8139: TX buffer " << i << ": " << m_tx_buffers[i]->vmobject().physical_pages()[0]->paddr();
klog() << "RTL8139: TX buffer " << i << ": " << m_tx_buffers[i]->physical_page(0)->paddr();
}
reset();
@ -250,7 +250,7 @@ void RTL8139NetworkAdapter::reset()
// device might be in sleep mode, this will take it out
out8(REG_CONFIG1, 0);
// set up rx buffer
out32(REG_RXBUF, m_rx_buffer->vmobject().physical_pages()[0]->paddr().get());
out32(REG_RXBUF, m_rx_buffer->physical_page(0)->paddr().get());
// reset missed packet counter
out8(REG_MPC, 0);
// "basic mode control register" options - 100mbit, full duplex, auto
@ -268,7 +268,7 @@ void RTL8139NetworkAdapter::reset()
out32(REG_TXCFG, TXCFG_TXRR_ZERO | TXCFG_MAX_DMA_1K | TXCFG_IFG11);
// tell the chip where we want it to DMA from for outgoing packets.
for (int i = 0; i < 4; i++)
out32(REG_TXADDR0 + (i * 4), m_tx_buffers[i]->vmobject().physical_pages()[0]->paddr().get());
out32(REG_TXADDR0 + (i * 4), m_tx_buffers[i]->physical_page(0)->paddr().get());
// re-lock config registers
out8(REG_CFG9346, CFG9346_NONE);
// enable rx/tx again in case they got turned off (apparently some cards

2
Kernel/PCI/MMIOAccess.cpp
View file

@ -141,7 +141,7 @@ void MMIOAccess::map_device(Address address)
dbg() << "PCI: Mapping device @ pci (" << String::format("%w", address.seg()) << ":" << String::format("%b", address.bus()) << ":" << String::format("%b", address.slot()) << "." << String::format("%b", address.function()) << ")"
<< " V 0x" << String::format("%x", m_mmio_window_region->vaddr().get()) << " P 0x" << String::format("%x", device_physical_mmio_space.get());
#endif
m_mmio_window_region->vmobject().physical_pages()[0] = PhysicalPage::create(device_physical_mmio_space, false, false);
m_mmio_window_region->physical_page_slot(0) = PhysicalPage::create(device_physical_mmio_space, false, false);
m_mmio_window_region->remap();
m_mapped_address = address;
}

56
Kernel/VM/Region.cpp
View file

@ -131,7 +131,7 @@ bool Region::commit(size_t page_index)
{
ASSERT(vmobject().is_anonymous() || vmobject().is_purgeable());
InterruptDisabler disabler;
auto& vmobject_physical_page_entry = vmobject().physical_pages()[first_page_index() + page_index];
auto& vmobject_physical_page_entry = physical_page_slot(page_index);
if (!vmobject_physical_page_entry.is_null() && !vmobject_physical_page_entry->is_shared_zero_page())
return true;
auto physical_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::Yes);
@ -165,8 +165,8 @@ size_t Region::amount_resident() const
{
size_t bytes = 0;
for (size_t i = 0; i < page_count(); ++i) {
auto& physical_page = m_vmobject->physical_pages()[first_page_index() + i];
if (physical_page && !physical_page->is_shared_zero_page())
auto* page = physical_page(i);
if (page && !page->is_shared_zero_page())
bytes += PAGE_SIZE;
}
return bytes;
@ -176,8 +176,8 @@ size_t Region::amount_shared() const
{
size_t bytes = 0;
for (size_t i = 0; i < page_count(); ++i) {
auto& physical_page = m_vmobject->physical_pages()[first_page_index() + i];
if (physical_page && physical_page->ref_count() > 1 && !physical_page->is_shared_zero_page())
auto* page = physical_page(i);
if (page && page->ref_count() > 1 && !page->is_shared_zero_page())
bytes += PAGE_SIZE;
}
return bytes;
@ -199,8 +199,8 @@ NonnullOwnPtr<Region> Region::create_kernel_only(const Range& range, NonnullRefP
bool Region::should_cow(size_t page_index) const
{
auto& slot = vmobject().physical_pages()[page_index];
if (slot && slot->is_shared_zero_page())
auto* page = physical_page(page_index);
if (page && page->is_shared_zero_page())
return true;
if (m_shared)
return false;
@ -224,12 +224,12 @@ void Region::map_individual_page_impl(size_t page_index)
{
auto page_vaddr = vaddr().offset(page_index * PAGE_SIZE);
auto& pte = MM.ensure_pte(*m_page_directory, page_vaddr);
auto& physical_page = vmobject().physical_pages()[first_page_index() + page_index];
if (!physical_page || (!is_readable() && !is_writable())) {
auto* page = physical_page(page_index);
if (!page || (!is_readable() && !is_writable())) {
pte.clear();
} else {
pte.set_cache_disabled(!m_cacheable);
pte.set_physical_page_base(physical_page->paddr().get());
pte.set_physical_page_base(page->paddr().get());
pte.set_present(true);
if (should_cow(page_index))
pte.set_writable(false);
@ -239,7 +239,7 @@ 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 << " => " << page->paddr() << " (@" << page << ")";
#endif
}
MM.flush_tlb(page_vaddr);
@ -249,7 +249,7 @@ void Region::remap_page(size_t page_index)
{
ASSERT(m_page_directory);
InterruptDisabler disabler;
ASSERT(vmobject().physical_pages()[first_page_index() + page_index]);
ASSERT(physical_page(page_index));
map_individual_page_impl(page_index);
}
@ -263,8 +263,8 @@ void Region::unmap(ShouldDeallocateVirtualMemoryRange deallocate_range)
pte.clear();
MM.flush_tlb(vaddr);
#ifdef MM_DEBUG
auto& physical_page = vmobject().physical_pages()[first_page_index() + i];
dbg() << "MM: >> Unmapped " << vaddr << " => P" << String::format("%p", physical_page ? physical_page->paddr().get() : 0) << " <<";
auto* page = physical_page(i);
dbg() << "MM: >> Unmapped " << vaddr << " => P" << String::format("%p", page ? page->paddr().get() : 0) << " <<";
#endif
}
if (deallocate_range == ShouldDeallocateVirtualMemoryRange::Yes)
@ -315,7 +315,7 @@ PageFaultResponse Region::handle_fault(const PageFault& fault)
}
#ifdef MAP_SHARED_ZERO_PAGE_LAZILY
if (fault.is_read()) {
vmobject().physical_pages()[first_page_index() + page_index_in_region] = MM.shared_zero_page();
physical_page_slot(page_index_in_region) = MM.shared_zero_page();
remap_page(page_index_in_region);
return PageFaultResponse::Continue;
}
@ -330,7 +330,7 @@ PageFaultResponse Region::handle_fault(const PageFault& fault)
#ifdef PAGE_FAULT_DEBUG
dbg() << "PV(cow) fault in Region{" << this << "}[" << page_index_in_region << "]";
#endif
if (vmobject().physical_pages()[first_page_index() + page_index_in_region]->is_shared_zero_page()) {
if (physical_page(page_index_in_region)->is_shared_zero_page()) {
#ifdef PAGE_FAULT_DEBUG
dbg() << "NP(zero) fault in Region{" << this << "}[" << page_index_in_region << "]";
#endif
@ -351,9 +351,9 @@ PageFaultResponse Region::handle_zero_fault(size_t page_index_in_region)
LOCKER(vmobject().m_paging_lock);
cli();
auto& vmobject_physical_page_entry = vmobject().physical_pages()[first_page_index() + page_index_in_region];
auto& page_slot = physical_page_slot(page_index_in_region);
if (!vmobject_physical_page_entry.is_null() && !vmobject_physical_page_entry->is_shared_zero_page()) {
if (!page_slot.is_null() && !page_slot->is_shared_zero_page()) {
#ifdef PAGE_FAULT_DEBUG
dbg() << "MM: zero_page() but page already present. Fine with me!";
#endif
@ -364,8 +364,8 @@ PageFaultResponse Region::handle_zero_fault(size_t page_index_in_region)
if (Thread::current)
Thread::current->did_zero_fault();
auto physical_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::Yes);
if (physical_page.is_null()) {
auto page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::Yes);
if (page.is_null()) {
klog() << "MM: handle_zero_fault was unable to allocate a physical page";
return PageFaultResponse::ShouldCrash;
}
@ -373,7 +373,7 @@ PageFaultResponse Region::handle_zero_fault(size_t page_index_in_region)
#ifdef PAGE_FAULT_DEBUG
dbg() << " >> ZERO " << physical_page->paddr();
#endif
vmobject_physical_page_entry = move(physical_page);
page_slot = move(page);
remap_page(page_index_in_region);
return PageFaultResponse::Continue;
}
@ -381,8 +381,8 @@ PageFaultResponse Region::handle_zero_fault(size_t page_index_in_region)
PageFaultResponse Region::handle_cow_fault(size_t page_index_in_region)
{
ASSERT_INTERRUPTS_DISABLED();
auto& vmobject_physical_page_entry = vmobject().physical_pages()[first_page_index() + page_index_in_region];
if (vmobject_physical_page_entry->ref_count() == 1) {
auto& page_slot = physical_page_slot(page_index_in_region);
if (page_slot->ref_count() == 1) {
#ifdef PAGE_FAULT_DEBUG
dbg() << " >> It's a COW page but nobody is sharing it anymore. Remap r/w";
#endif
@ -397,19 +397,19 @@ PageFaultResponse Region::handle_cow_fault(size_t page_index_in_region)
#ifdef PAGE_FAULT_DEBUG
dbg() << " >> It's a COW page and it's time to COW!";
#endif
auto physical_page_to_copy = move(vmobject_physical_page_entry);
auto physical_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::No);
if (physical_page.is_null()) {
auto physical_page_to_copy = move(page_slot);
auto page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::No);
if (page.is_null()) {
klog() << "MM: handle_cow_fault was unable to allocate a physical page";
return PageFaultResponse::ShouldCrash;
}
u8* dest_ptr = MM.quickmap_page(*physical_page);
u8* dest_ptr = MM.quickmap_page(*page);
const u8* src_ptr = vaddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
#ifdef PAGE_FAULT_DEBUG
dbg() << " >> COW " << physical_page->paddr() << " <- " << physical_page_to_copy->paddr();
#endif
copy_from_user(dest_ptr, src_ptr, PAGE_SIZE);
vmobject_physical_page_entry = move(physical_page);
page_slot = move(page);
MM.unquickmap_page();
set_should_cow(page_index_in_region, false);
remap_page(page_index_in_region);

12
Kernel/VM/Region.h
View file

@ -128,6 +128,18 @@ public:
return size() / PAGE_SIZE;
}
const PhysicalPage* physical_page(size_t index) const
{
ASSERT(index < page_count());
return vmobject().physical_pages()[first_page_index() + index];
}
RefPtr<PhysicalPage>& physical_page_slot(size_t index)
{
ASSERT(index < page_count());
return vmobject().physical_pages()[first_page_index() + index];
}
size_t offset_in_vmobject() const
{
return m_offset_in_vmobject;