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KytyPS5/src/graphics/host_gpu/pageManager.cpp
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nmzik f6e01e5403 Optimize bulk memory invalidation (#124) 
* Per page -> per range search (optimization)
2026-07-29 05:09:36 +02:00

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#include "graphics/host_gpu/pageManager.h"
#include "graphics/host_gpu/regionDefinitions.h"
#include <algorithm>
#include <array>
#include <atomic>
#include <cstdarg>
#include <cstdio>
#include <cstdlib>
#include <limits>
#include <memory>
#include <mutex>
#include <vector>
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
#ifndef NOMINMAX
#define NOMINMAX
#endif
#include <windows.h>
#undef min
#undef max
#elif defined(__APPLE__)
#include <mach/mach.h>
#include <mach/mach_vm.h>
#include <pthread.h>
#include <sys/mman.h>
#include <unistd.h>
#else
#include <cerrno>
#include <cstring>
#include <execinfo.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <unistd.h>
#endif
namespace Libs::Graphics {
namespace {
constexpr uint64_t PAGE_SIZE = TRACKER_PAGE_SIZE;
constexpr uint64_t REGION_SIZE = TRACKER_REGION_SIZE;
constexpr uint64_t ADDRESS_SIZE = TRACKER_ADDRESS_SIZE;
constexpr uint64_t REGION_COUNT = ADDRESS_SIZE / REGION_SIZE;
#if KYTY_PLATFORM != KYTY_PLATFORM_WINDOWS
// The tracker reuses Win32 memory-protection tags as internal page-state values (on
// Windows they come from <windows.h> and are what VirtualQuery returns). Mirror the
// canonical Win32 numeric values so the shared state-machine logic is identical.
constexpr uint32_t PAGE_NOACCESS = 0x01;
constexpr uint32_t PAGE_READONLY = 0x02;
constexpr uint32_t PAGE_READWRITE = 0x04;
#endif
constexpr uint64_t REGION_PAGES = REGION_SIZE / PAGE_SIZE;
constexpr uint32_t NO_ACCESS_PROTECTION = PAGE_NOACCESS;
constexpr uint32_t READ_ONLY_PROTECTION = PAGE_READONLY;
constexpr uint32_t READ_WRITE_PROTECTION = PAGE_READWRITE;
#if defined(__APPLE__)
// Map the tracker's Win32-style protection tags to POSIX mprotect flags.
static int PageProtToPosix(uint32_t protection) {
switch (protection) {
case PAGE_NOACCESS: return PROT_NONE;
case PAGE_READONLY: return PROT_READ;
case PAGE_READWRITE: return PROT_READ | PROT_WRITE;
default: return PROT_NONE;
}
}
// Query the current protection of the page containing vaddr via the Mach VM map and
// collapse it to the tracker's read/write tags (execute is irrelevant to write tracking).
static uint32_t MachQueryPageProt(uint64_t vaddr) {
auto region_addr = static_cast<mach_vm_address_t>(vaddr);
mach_vm_size_t region_size = 0;
vm_region_basic_info_data_64_t info {};
mach_msg_type_number_t count = VM_REGION_BASIC_INFO_COUNT_64;
mach_port_t object_name = MACH_PORT_NULL;
kern_return_t kr =
mach_vm_region(mach_task_self(), &region_addr, &region_size, VM_REGION_BASIC_INFO_64,
reinterpret_cast<vm_region_info_t>(&info), &count, &object_name);
if (kr != KERN_SUCCESS || region_addr > vaddr) {
return PAGE_NOACCESS; // no region covering vaddr
}
if ((info.protection & VM_PROT_WRITE) != 0) {
return PAGE_READWRITE;
}
if ((info.protection & VM_PROT_READ) != 0) {
return PAGE_READONLY;
}
return PAGE_NOACCESS;
}
#elif defined(__linux__)
// Zero is the unknown protection sentinel.
constexpr uint32_t UNKNOWN_PROTECTION = 0;
#endif
thread_local bool g_in_fault_resolution = false;
[[noreturn]] void FailFast(const char* reason = nullptr) noexcept {
std::fputs("PageManager fail-fast: ", stderr);
std::fputs(reason != nullptr ? reason : "invalid page state", stderr);
std::fputc('\n', stderr);
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
void* frames[16] {};
const auto frame_count =
CaptureStackBackTrace(0, static_cast<DWORD>(std::size(frames)), frames, nullptr);
const auto image_base = reinterpret_cast<uintptr_t>(GetModuleHandleW(nullptr));
for (uint16_t i = 0; i < frame_count; i++) {
const auto address = reinterpret_cast<uintptr_t>(frames[i]);
std::fprintf(stderr, " frame[%u]=0x%016" PRIxPTR " image_rva=0x%016" PRIxPTR "\n", i,
address, address >= image_base ? address - image_base : 0);
}
#elif !defined(__APPLE__)
void* frames[16] {};
const int frame_count = ::backtrace(frames, static_cast<int>(std::size(frames)));
::backtrace_symbols_fd(frames, frame_count, STDERR_FILENO);
#endif
std::fflush(stderr);
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
TerminateProcess(GetCurrentProcess(), static_cast<UINT>(EXCEPTION_NONCONTINUABLE_EXCEPTION));
#endif
std::_Exit(322);
}
[[noreturn]] void Fatal(const char* format, ...) {
std::fputs("PageManager fatal: ", stderr);
va_list args;
va_start(args, format);
std::vfprintf(stderr, format, args);
va_end(args);
std::fputc('\n', stderr);
std::fflush(stderr);
std::_Exit(322);
}
uint32_t CurrentThread() noexcept {
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
return GetCurrentThreadId();
#elif defined(__APPLE__)
return static_cast<uint32_t>(pthread_mach_thread_np(pthread_self()));
#elif defined(__linux__)
static thread_local const uint32_t tid = [] {
const auto raw = static_cast<uint32_t>(::syscall(SYS_gettid));
if (raw == 0) {
FailFast("gettid returned the reserved zero owner token");
}
return raw;
}();
return tid;
#else
FailFast("page tracking thread identity is unsupported on this platform");
#endif
}
#if defined(__linux__)
int ToHostProtection(uint32_t protection) {
switch (protection) {
case NO_ACCESS_PROTECTION: return PROT_NONE;
case READ_ONLY_PROTECTION: return PROT_READ;
case READ_WRITE_PROTECTION: return PROT_READ | PROT_WRITE;
default: Fatal("unmappable protection 0x%08" PRIx32, protection);
}
}
struct HostMapping {
uint64_t end = 0;
uint32_t protection = UNKNOWN_PROTECTION;
};
// Async-signal-safe lookup in the address-ordered /proc/self/maps.
HostMapping QueryHostMapping(uint64_t vaddr) noexcept {
int fd = ::open("/proc/self/maps", O_RDONLY | O_CLOEXEC); // NOLINT
if (fd < 0) {
return {};
}
enum class Field { Start, End, Perms, Rest };
HostMapping result {};
auto field = Field::Start;
uint64_t start = 0;
uint64_t end = 0;
char perms[4] = {};
uint32_t perms_len = 0;
bool line_valid = true;
char buffer[8192];
for (bool done = false; !done;) {
const auto got = ::read(fd, buffer, sizeof(buffer));
if (got < 0) {
if (errno == EINTR) {
continue;
}
break;
}
if (got == 0) {
break;
}
for (ssize_t i = 0; i < got && !done; i++) {
const char c = buffer[i];
if (c == '\n') {
field = Field::Start;
start = 0;
end = 0;
perms_len = 0;
line_valid = true;
continue;
}
if (!line_valid) {
continue;
}
switch (field) {
case Field::Start:
case Field::End: {
uint64_t digit = 0;
if (c >= '0' && c <= '9') {
digit = static_cast<uint64_t>(c - '0');
} else if (c >= 'a' && c <= 'f') {
digit = static_cast<uint64_t>(c - 'a') + 10;
} else if (c == '-' && field == Field::Start) {
field = Field::End;
break;
} else if (c == ' ' && field == Field::End) {
field = Field::Perms;
perms_len = 0;
break;
} else {
line_valid = false;
break;
}
auto& value = (field == Field::Start ? start : end);
value = (value << 4u) | digit;
break;
}
case Field::Perms: {
if (c != ' ') {
if (perms_len < sizeof(perms)) {
perms[perms_len] = c;
}
perms_len++;
break;
}
if (vaddr < start) {
done = true;
} else if (vaddr < end && perms_len >= 2) {
result.end = end;
result.protection = perms[1] == 'w' ? READ_WRITE_PROTECTION
: perms[0] == 'r' ? READ_ONLY_PROTECTION
: NO_ACCESS_PROTECTION;
done = true;
} else {
field = Field::Rest;
}
break;
}
case Field::Rest: break;
}
}
}
::close(fd);
return result;
}
uint32_t QueryHostProtection(uint64_t vaddr) noexcept {
return QueryHostMapping(vaddr).protection;
}
#endif
class SpinGuard final {
public:
explicit SpinGuard(std::atomic_flag& lock): m_lock(lock) {
while (m_lock.test_and_set(std::memory_order_acquire)) {
std::atomic_signal_fence(std::memory_order_seq_cst);
}
}
~SpinGuard() { m_lock.clear(std::memory_order_release); }
KYTY_CLASS_NO_COPY(SpinGuard);
private:
std::atomic_flag& m_lock;
};
void ValidateRange(uint64_t vaddr, uint64_t size) {
if (vaddr == 0 || size == 0 || vaddr >= ADDRESS_SIZE || size > ADDRESS_SIZE - vaddr) {
Fatal("invalid range vaddr=0x%016" PRIx64 ", size=0x%016" PRIx64, vaddr, size);
}
}
uint64_t PageStart(uint64_t vaddr) {
return vaddr & ~(PAGE_SIZE - 1);
}
uint64_t PageEnd(uint64_t vaddr, uint64_t size) {
ValidateRange(vaddr, size);
return PageStart(vaddr + size - 1) + PAGE_SIZE;
}
} // namespace
struct PageManager::Impl {
struct PageState {
std::atomic_flag lock = ATOMIC_FLAG_INIT;
uint32_t mappings = 0;
uint32_t gpu_read_mappings = 0;
uint32_t gpu_write_mappings = 0;
uint32_t write_watchers = 0;
uint32_t access_watchers = 0;
uint32_t original_protection = 0;
uint32_t backing_writer = 0;
#if defined(__linux__)
// Shadow the protection applied through Protect().
uint32_t current_protection = UNKNOWN_PROTECTION;
#endif
bool resolving = false;
bool resolving_read_write = false;
bool late_read_pending = false;
bool late_write_pending = false;
};
struct Region {
std::array<PageState, REGION_PAGES> pages;
};
class PageRangeGuard final {
public:
explicit PageRangeGuard(std::span<PageState*> pages): m_pages(pages) {
for (auto* page: m_pages) {
while (page->lock.test_and_set(std::memory_order_acquire)) {
std::atomic_signal_fence(std::memory_order_seq_cst);
}
}
}
~PageRangeGuard() {
for (auto it = m_pages.rbegin(); it != m_pages.rend(); ++it) {
(*it)->lock.clear(std::memory_order_release);
}
}
KYTY_CLASS_NO_COPY(PageRangeGuard);
private:
std::span<PageState*> m_pages;
};
Impl(PageFaultHandler handler, void* context): fault_handler(handler), fault_context(context) {
if (fault_handler == nullptr) {
Fatal("null fault handler");
}
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
SYSTEM_INFO info {};
GetSystemInfo(&info);
if (info.dwPageSize != PAGE_SIZE) {
Fatal("unsupported host page size 0x%08" PRIx32,
static_cast<uint32_t>(info.dwPageSize));
}
#elif defined(__APPLE__)
// Under Rosetta the host page size is 4 KB, matching TRACKER_PAGE_SIZE.
if (static_cast<uint64_t>(getpagesize()) != PAGE_SIZE) {
Fatal("unsupported host page size 0x%08" PRIx32, static_cast<uint32_t>(getpagesize()));
}
#else
const auto host_page_size = ::sysconf(_SC_PAGESIZE);
if (host_page_size < 0 || static_cast<uint64_t>(host_page_size) != PAGE_SIZE) {
Fatal("unsupported host page size %ld", static_cast<long>(host_page_size));
}
#endif
regions = std::make_unique<std::atomic<Region*>[]>(REGION_COUNT);
for (uint64_t i = 0; i < REGION_COUNT; i++) {
regions[i].store(nullptr, std::memory_order_relaxed);
}
}
~Impl() {
for (const auto& region: region_storage) {
for (auto& page: region->pages) {
SpinGuard lock(page.lock);
if (page.mappings != 0 || page.gpu_read_mappings != 0 ||
page.gpu_write_mappings != 0 || page.write_watchers != 0 ||
page.access_watchers != 0 || page.backing_writer != 0 || page.resolving) {
FailFast("PageManager destroyed with live page state");
}
}
}
}
Region* FindRegion(uint64_t vaddr) const noexcept {
return vaddr < ADDRESS_SIZE ? regions[vaddr / REGION_SIZE].load(std::memory_order_acquire)
: nullptr;
}
Region* GetOrCreateRegion(uint64_t vaddr) {
const auto index = vaddr / REGION_SIZE;
if (auto* region = regions[index].load(std::memory_order_acquire); region != nullptr) {
return region;
}
std::lock_guard lock(region_mutex);
if (auto* region = regions[index].load(std::memory_order_acquire); region != nullptr) {
return region;
}
auto region = std::make_unique<Region>();
auto* ptr = region.get();
region_storage.push_back(std::move(region));
regions[index].store(ptr, std::memory_order_release);
return ptr;
}
PageState& GetPage(Region& region, uint64_t vaddr) const {
return region.pages[(vaddr % REGION_SIZE) / PAGE_SIZE];
}
static uint32_t WatcherProtection(const PageState& page) {
if (page.access_watchers != 0) {
return NO_ACCESS_PROTECTION;
}
if (page.write_watchers != 0) {
return READ_ONLY_PROTECTION;
}
return page.original_protection;
}
static void PublishDelayedFaults(PageState& page, uint32_t old_protection,
uint32_t new_protection) {
if (old_protection == NO_ACCESS_PROTECTION && new_protection != NO_ACCESS_PROTECTION) {
page.late_read_pending = true;
}
if ((old_protection == NO_ACCESS_PROTECTION || old_protection == READ_ONLY_PROTECTION) &&
new_protection == READ_WRITE_PROTECTION) {
page.late_write_pending = true;
}
}
static void ValidateInitialProtection(std::span<PageState*> pages, uint64_t vaddr) {
const auto end = vaddr + pages.size() * PAGE_SIZE;
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
for (auto address = vaddr; address < end;) {
MEMORY_BASIC_INFORMATION info {};
if (VirtualQuery(reinterpret_cast<const void*>(static_cast<uintptr_t>(address)), &info,
sizeof(info)) == 0 ||
info.State != MEM_COMMIT || info.Protect != PAGE_READWRITE) {
Fatal("basic path requires PAGE_READWRITE at 0x%016" PRIx64 " (state=0x%08" PRIx32
", protection=0x%08" PRIx32 ")",
address, static_cast<uint32_t>(info.State),
static_cast<uint32_t>(info.Protect));
}
const auto region_end = reinterpret_cast<uint64_t>(info.BaseAddress) + info.RegionSize;
if (region_end <= address) {
Fatal("VirtualQuery returned an invalid region at 0x%016" PRIx64, address);
}
address = std::min(end, region_end);
}
#elif defined(__APPLE__)
for (auto address = vaddr; address < end; address += PAGE_SIZE) {
const uint32_t protection = MachQueryPageProt(address);
if (protection != PAGE_READWRITE) {
Fatal("basic path requires PAGE_READWRITE at 0x%016" PRIx64
" (protection=0x%08" PRIx32 ")",
address, protection);
}
}
#else
for (auto address = vaddr; address < end;) {
const auto mapping = QueryHostMapping(address);
if (mapping.protection != READ_WRITE_PROTECTION || mapping.end <= address) {
Fatal("basic path requires a read/write mapping at 0x%016" PRIx64
" (protection=0x%08" PRIx32 ")",
address, mapping.protection);
}
address = std::min(end, mapping.end);
}
for (auto* page: pages) {
page->current_protection = READ_WRITE_PROTECTION;
}
#endif
for (auto* page: pages) {
page->original_protection = READ_WRITE_PROTECTION;
}
}
static bool AllowsAccess([[maybe_unused]] const PageState& page, uint64_t vaddr,
PageFaultAccess access) noexcept {
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
MEMORY_BASIC_INFORMATION info {};
if (VirtualQuery(reinterpret_cast<const void*>(static_cast<uintptr_t>(vaddr)), &info,
sizeof(info)) == 0 ||
info.State != MEM_COMMIT) {
return false;
}
switch (access) {
case PageFaultAccess::Read:
return info.Protect == PAGE_READONLY || info.Protect == PAGE_READWRITE;
case PageFaultAccess::Write: return info.Protect == PAGE_READWRITE;
default: return false;
}
#elif defined(__APPLE__)
const uint32_t protection = MachQueryPageProt(vaddr);
switch (access) {
case PageFaultAccess::Read:
return protection == PAGE_READONLY || protection == PAGE_READWRITE;
case PageFaultAccess::Write: return protection == PAGE_READWRITE;
default: return false;
}
#else
const auto permitted = [](uint32_t protection, PageFaultAccess wanted) {
switch (wanted) {
case PageFaultAccess::Read:
return protection == READ_ONLY_PROTECTION ||
protection == READ_WRITE_PROTECTION;
case PageFaultAccess::Write: return protection == READ_WRITE_PROTECTION;
default: return false;
}
};
if (!permitted(page.current_protection, access)) {
return false;
}
return permitted(QueryHostProtection(vaddr), access);
#endif
}
static void ProtectRange(std::span<PageState*> pages, uint64_t vaddr, uint32_t protection,
std::span<const uint32_t> expected_old, bool fault_path) noexcept {
const auto size = pages.size() * PAGE_SIZE;
if (pages.size() != expected_old.size()) {
FailFast("protection range state size mismatch");
}
#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
struct HostRange {
uint64_t begin = 0;
uint64_t end = 0;
};
std::vector<HostRange> host_ranges;
const auto end = vaddr + size;
for (auto address = vaddr; address < end;) {
MEMORY_BASIC_INFORMATION info {};
if (VirtualQuery(reinterpret_cast<const void*>(static_cast<uintptr_t>(address)), &info,
sizeof(info)) == 0 ||
info.State != MEM_COMMIT) {
if (fault_path) {
FailFast("VirtualProtect fault transition did not match expected protection");
}
Fatal("invalid protection transition at 0x%016" PRIx64 ", state=0x%08" PRIx32
", new=0x%08" PRIx32,
address, static_cast<uint32_t>(info.State), protection);
}
const auto region_end = reinterpret_cast<uint64_t>(info.BaseAddress) + info.RegionSize;
const auto query_end = std::min(end, region_end);
if (query_end <= address) {
if (fault_path) {
FailFast("VirtualQuery returned an invalid fault transition region");
}
Fatal("VirtualQuery returned an invalid region at 0x%016" PRIx64, address);
}
const auto first_page = static_cast<size_t>((address - vaddr) / PAGE_SIZE);
const auto last_page =
static_cast<size_t>((query_end - vaddr + PAGE_SIZE - 1) / PAGE_SIZE);
for (auto page = first_page; page < last_page; page++) {
if (info.Protect != expected_old[page]) {
if (fault_path) {
FailFast(
"VirtualProtect fault transition did not match expected protection");
}
Fatal("invalid protection transition at 0x%016" PRIx64 ", actual=0x%08" PRIx32
", expected=0x%08" PRIx32 ", new=0x%08" PRIx32,
vaddr + page * PAGE_SIZE, static_cast<uint32_t>(info.Protect),
expected_old[page], protection);
}
}
const auto allocation = reinterpret_cast<uint64_t>(info.AllocationBase);
if (host_ranges.empty() || allocation != host_ranges.back().begin) {
host_ranges.push_back({allocation, query_end});
} else {
host_ranges.back().end = query_end;
}
address = query_end;
}
for (auto range: host_ranges) {
range.begin = std::max(range.begin, vaddr);
DWORD old_protection = 0;
const auto first_page = static_cast<size_t>((range.begin - vaddr) / PAGE_SIZE);
if (VirtualProtect(reinterpret_cast<void*>(static_cast<uintptr_t>(range.begin)),
range.end - range.begin, protection, &old_protection) == 0 ||
old_protection != expected_old[first_page]) {
if (fault_path) {
FailFast("VirtualProtect fault transition did not match expected protection");
}
Fatal("invalid protection transition at 0x%016" PRIx64 ", old=0x%08" PRIx32
", expected=0x%08" PRIx32 ", new=0x%08" PRIx32,
range.begin, static_cast<uint32_t>(old_protection), expected_old[first_page],
protection);
}
}
#elif defined(__APPLE__)
// mprotect cannot report the previous protection, so the expected_old comparison
// is dropped; the tracker is the sole mutator of these pages and drives the
// transition from its own shadow state.
(void)expected_old;
if (mprotect(reinterpret_cast<void*>(static_cast<uintptr_t>(vaddr)), size,
PageProtToPosix(protection)) != 0) {
if (fault_path) {
FailFast("mprotect fault transition failed");
}
Fatal("mprotect failed at 0x%016" PRIx64 ", new=0x%08" PRIx32, vaddr, protection);
}
#else
for (size_t i = 0; i < pages.size(); i++) {
const auto actual = pages[i]->current_protection;
if (actual != UNKNOWN_PROTECTION && actual != expected_old[i]) {
if (fault_path) {
FailFast("mprotect fault transition did not match expected protection");
}
Fatal("invalid protection transition at 0x%016" PRIx64 ", old=0x%08" PRIx32
", expected=0x%08" PRIx32 ", new=0x%08" PRIx32,
vaddr + i * PAGE_SIZE, actual, expected_old[i], protection);
}
}
if (::mprotect(reinterpret_cast<void*>(static_cast<uintptr_t>(vaddr)), size,
ToHostProtection(protection)) != 0) {
if (fault_path) {
FailFast("mprotect failed on the fault path");
}
Fatal("mprotect failed at 0x%016" PRIx64 ", new=0x%08" PRIx32 " (%s)", vaddr,
protection, std::strerror(errno));
}
for (auto* page: pages) {
page->current_protection = protection;
}
#endif
}
static void Protect(PageState& page, uint64_t vaddr, uint32_t protection, uint32_t expected_old,
bool fault_path) noexcept {
PageState* pages[] = {&page};
uint32_t expected[] = {expected_old};
ProtectRange(pages, vaddr, protection, expected, fault_path);
}
std::unique_ptr<std::atomic<Region*>[]> regions;
std::vector<std::unique_ptr<Region>> region_storage;
std::mutex region_mutex;
PageFaultHandler fault_handler = nullptr;
void* fault_context = nullptr;
};
static_assert(std::atomic<void*>::is_always_lock_free);
PageManager::PageManager(PageFaultHandler fault_handler, void* fault_context)
: m_impl(std::make_unique<Impl>(fault_handler, fault_context)) {}
PageManager::~PageManager() = default;
uint64_t PageManager::GetPageSize() const {
if (g_in_fault_resolution) {
FailFast("nested page fault while resolving a watched page");
}
return PAGE_SIZE;
}
bool PageManager::IsTracked(uint64_t vaddr) const noexcept {
if (g_in_fault_resolution) {
FailFast("IsTracked called during fault resolution");
}
auto* region = m_impl->FindRegion(vaddr);
if (region == nullptr) {
return false;
}
auto& page = m_impl->GetPage(*region, vaddr);
SpinGuard lock(page.lock);
return page.write_watchers != 0 || page.access_watchers != 0;
}
bool PageManager::IsMapped(uint64_t vaddr, uint64_t size) const noexcept {
if (vaddr == 0 || size == 0 || vaddr >= ADDRESS_SIZE || size > ADDRESS_SIZE - vaddr) {
return false;
}
const auto end = PageStart(vaddr + size - 1) + PAGE_SIZE;
for (auto page_vaddr = PageStart(vaddr); page_vaddr < end; page_vaddr += PAGE_SIZE) {
auto* region = m_impl->FindRegion(page_vaddr);
if (region == nullptr) {
return false;
}
auto& page = m_impl->GetPage(*region, page_vaddr);
SpinGuard lock(page.lock);
if (page.mappings == 0) {
return false;
}
}
return true;
}
bool PageManager::HasGpuAccess(uint64_t vaddr, uint64_t size, GpuAccess access) const noexcept {
if (access != GpuAccess::Read && access != GpuAccess::Write && access != GpuAccess::ReadWrite) {
FailFast("HasGpuAccess received an invalid GPU access mode");
}
const bool need_read = access == GpuAccess::Read || access == GpuAccess::ReadWrite;
const bool need_write = access == GpuAccess::Write || access == GpuAccess::ReadWrite;
if (vaddr == 0 || size == 0 || vaddr >= ADDRESS_SIZE || size > ADDRESS_SIZE - vaddr) {
return false;
}
const auto end = PageEnd(vaddr, size);
for (auto addr = PageStart(vaddr); addr < end; addr += PAGE_SIZE) {
auto* region = m_impl->FindRegion(addr);
if (region == nullptr) {
return false;
}
auto& page = m_impl->GetPage(*region, addr);
SpinGuard lock(page.lock);
if ((need_read && page.gpu_read_mappings == 0) ||
(need_write && page.gpu_write_mappings == 0)) {
return false;
}
}
return true;
}
void PageManager::UpdatePageWatchers(bool track, uint64_t vaddr, uint64_t size,
PageWatchMode mode) {
if (mode != PageWatchMode::Write && mode != PageWatchMode::ReadWrite) {
Fatal("invalid watcher mode");
}
const auto begin = PageStart(vaddr);
const auto end = PageEnd(vaddr, size);
for (auto chunk_begin = begin; chunk_begin < end;) {
const auto chunk_end = std::min(end, (chunk_begin / REGION_SIZE + 1) * REGION_SIZE);
auto* region =
track ? m_impl->GetOrCreateRegion(chunk_begin) : m_impl->FindRegion(chunk_begin);
if (region == nullptr) {
Fatal("untracking unknown page 0x%016" PRIx64, chunk_begin);
}
const auto page_count = static_cast<size_t>((chunk_end - chunk_begin) / PAGE_SIZE);
std::vector<Impl::PageState*> pages;
pages.reserve(page_count);
for (auto address = chunk_begin; address < chunk_end; address += PAGE_SIZE) {
pages.push_back(&m_impl->GetPage(*region, address));
}
Impl::PageRangeGuard lock(pages);
std::vector<uint8_t> first_watchers(page_count);
for (size_t i = 0; i < page_count; i++) {
auto& page = *pages[i];
const auto address = chunk_begin + i * PAGE_SIZE;
if (page.resolving && track) {
FailFast("new page watcher raced active fault resolution");
}
if (page.mappings == 0) {
Fatal("watching unmapped page 0x%016" PRIx64, address);
}
auto& watchers =
(mode == PageWatchMode::ReadWrite ? page.access_watchers : page.write_watchers);
if (track) {
if (watchers == std::numeric_limits<uint32_t>::max()) {
Fatal("watcher overflow at 0x%016" PRIx64, address);
}
first_watchers[i] = page.write_watchers == 0 && page.access_watchers == 0;
} else {
if (watchers == 0) {
Fatal("watcher underflow at 0x%016" PRIx64, address);
}
if (page.backing_writer != 0 && page.backing_writer != CurrentThread()) {
Fatal("backing write ownership changed at 0x%016" PRIx64, address);
}
}
}
if (track) {
for (size_t first = 0; first < page_count;) {
while (first < page_count && first_watchers[first] == 0) {
first++;
}
auto last = first;
while (last < page_count && first_watchers[last] != 0) {
last++;
}
if (first != last) {
Impl::ValidateInitialProtection(std::span {pages}.subspan(first, last - first),
chunk_begin + first * PAGE_SIZE);
}
first = last;
}
}
std::vector<uint32_t> old_protections(page_count);
std::vector<uint32_t> new_protections(page_count);
std::vector<uint8_t> transitions(page_count);
for (size_t i = 0; i < page_count; i++) {
auto& page = *pages[i];
auto& watchers =
(mode == PageWatchMode::ReadWrite ? page.access_watchers : page.write_watchers);
const auto old_protection = Impl::WatcherProtection(page);
if (track) {
watchers++;
} else {
watchers--;
}
const auto new_protection = Impl::WatcherProtection(page);
old_protections[i] = old_protection;
new_protections[i] = new_protection;
if (new_protection != old_protection && (track || page.backing_writer == 0)) {
transitions[i] = 1;
}
}
for (size_t first = 0; first < page_count;) {
while (first < page_count && transitions[first] == 0) {
first++;
}
if (first == page_count) {
break;
}
const auto protection = new_protections[first];
auto current = first + 1;
auto last = current;
for (; current < page_count && new_protections[current] == protection; current++) {
if (old_protections[current] != new_protections[current] &&
transitions[current] == 0) {
break;
}
if (transitions[current] != 0) {
last = current + 1;
}
}
Impl::ProtectRange(std::span {pages}.subspan(first, last - first),
chunk_begin + first * PAGE_SIZE, protection,
std::span {old_protections}.subspan(first, last - first), false);
first = current;
}
for (size_t i = 0; i < page_count; i++) {
auto& page = *pages[i];
const auto protection = new_protections[i];
if (track) {
switch (protection) {
case NO_ACCESS_PROTECTION:
page.late_read_pending = false;
page.late_write_pending = false;
break;
case READ_ONLY_PROTECTION: page.late_write_pending = false; break;
default: break;
}
} else if (page.backing_writer == 0) {
Impl::PublishDelayedFaults(page, old_protections[i], protection);
if (page.write_watchers == 0 && page.access_watchers == 0) {
page.original_protection = 0;
}
}
}
chunk_begin = chunk_end;
}
}
void PageManager::OnGpuMap(uint64_t vaddr, uint64_t size, GpuAccess access) {
if (g_in_fault_resolution) {
FailFast("GPU mapping changed during fault resolution");
}
if (access != GpuAccess::Read && access != GpuAccess::Write && access != GpuAccess::ReadWrite) {
FailFast("GPU map received an invalid access mode");
}
const bool gpu_read = access == GpuAccess::Read || access == GpuAccess::ReadWrite;
const bool gpu_write = access == GpuAccess::Write || access == GpuAccess::ReadWrite;
const auto end = PageEnd(vaddr, size);
for (auto addr = PageStart(vaddr); addr < end; addr += PAGE_SIZE) {
auto& page = m_impl->GetPage(*m_impl->GetOrCreateRegion(addr), addr);
SpinGuard lock(page.lock);
if (page.resolving || page.mappings == std::numeric_limits<uint32_t>::max() ||
(gpu_read && page.gpu_read_mappings == std::numeric_limits<uint32_t>::max()) ||
(gpu_write && page.gpu_write_mappings == std::numeric_limits<uint32_t>::max())) {
Fatal("invalid map state at 0x%016" PRIx64, addr);
}
page.mappings++;
page.gpu_read_mappings += gpu_read ? 1u : 0u;
page.gpu_write_mappings += gpu_write ? 1u : 0u;
#if defined(__linux__)
// New guest mappings start read/write.
if (page.current_protection == UNKNOWN_PROTECTION) {
page.current_protection = READ_WRITE_PROTECTION;
}
#endif
}
}
void PageManager::OnGpuUnmap(uint64_t vaddr, uint64_t size, GpuAccess access) {
if (g_in_fault_resolution) {
FailFast("GPU unmapping changed during fault resolution");
}
if (access != GpuAccess::Read && access != GpuAccess::Write && access != GpuAccess::ReadWrite) {
FailFast("GPU unmap received an invalid access mode");
}
const bool gpu_read = access == GpuAccess::Read || access == GpuAccess::ReadWrite;
const bool gpu_write = access == GpuAccess::Write || access == GpuAccess::ReadWrite;
const auto end = PageEnd(vaddr, size);
for (auto page_vaddr = PageStart(vaddr); page_vaddr < end; page_vaddr += PAGE_SIZE) {
auto* region = m_impl->FindRegion(page_vaddr);
if (region == nullptr) {
Fatal("unmapping unknown page 0x%016" PRIx64, page_vaddr);
}
auto& page = m_impl->GetPage(*region, page_vaddr);
SpinGuard lock(page.lock);
if (page.resolving || page.mappings == 0 || (gpu_read && page.gpu_read_mappings == 0) ||
(gpu_write && page.gpu_write_mappings == 0) ||
(page.mappings == 1 && (page.write_watchers != 0 || page.access_watchers != 0))) {
Fatal("invalid unmap state at 0x%016" PRIx64, page_vaddr);
}
page.mappings--;
page.gpu_read_mappings -= gpu_read ? 1u : 0u;
page.gpu_write_mappings -= gpu_write ? 1u : 0u;
if (page.mappings == 0) {
if (page.gpu_read_mappings != 0 || page.gpu_write_mappings != 0) {
FailFast("GPU unmap left nonzero GPU mapping counts");
}
page.late_read_pending = false;
page.late_write_pending = false;
}
}
}
PageManager::BackingWrite::BackingWrite(PageManager& manager, uint64_t vaddr,
uint64_t size) noexcept
: m_manager(manager), m_vaddr(vaddr), m_size(size) {
m_manager.BeginBackingWrite(vaddr, size);
}
PageManager::BackingWrite::~BackingWrite() {
m_manager.EndBackingWrite(m_vaddr, m_size);
}
std::vector<std::unique_ptr<PageManager::BackingWrite>>
PageManager::ReserveBackingWrites(std::span<const RangeSet::Range> ranges) {
if (ranges.empty()) {
Fatal("cannot reserve empty backing-write ranges");
}
std::vector<std::unique_ptr<BackingWrite>> writes;
writes.reserve(ranges.size());
uint64_t begin = 0;
uint64_t end = 0;
for (const auto& range: ranges) {
if (range.address == 0 || range.size == 0 || range.size > UINT64_MAX - range.address ||
range.address + range.size > UINT64_MAX - (PAGE_SIZE - 1)) {
Fatal("invalid backing-write range");
}
const auto page_begin = PageStart(range.address);
const auto page_end = PageStart(range.address + range.size + PAGE_SIZE - 1);
if (begin != 0 && page_begin > end) {
writes.push_back(std::make_unique<BackingWrite>(*this, begin, end - begin));
begin = 0;
}
if (begin == 0) {
begin = page_begin;
end = page_end;
} else {
end = std::max(end, page_end);
}
}
writes.push_back(std::make_unique<BackingWrite>(*this, begin, end - begin));
return writes;
}
void PageManager::BeginBackingWrite(uint64_t vaddr, uint64_t size) noexcept {
if (g_in_fault_resolution) {
FailFast("backing write began during fault resolution");
}
const auto end = PageEnd(vaddr, size);
const auto writer = CurrentThread();
for (auto address = PageStart(vaddr); address < end; address += PAGE_SIZE) {
auto* region = m_impl->FindRegion(address);
if (region == nullptr) {
Fatal("backing write reserves an unknown page at 0x%016" PRIx64, address);
}
auto& page = m_impl->GetPage(*region, address);
SpinGuard lock(page.lock);
if (page.mappings == 0 || page.resolving || page.backing_writer != 0 ||
page.access_watchers == 0) {
Fatal("backing write races page resolution at 0x%016" PRIx64, address);
}
page.resolving = true;
page.resolving_read_write = true;
page.backing_writer = writer;
}
}
void PageManager::EndBackingWrite(uint64_t vaddr, uint64_t size) noexcept {
if (g_in_fault_resolution) {
FailFast("backing write ended during fault resolution");
}
const auto end = PageEnd(vaddr, size);
const auto writer = CurrentThread();
for (auto address = PageStart(vaddr); address < end; address += PAGE_SIZE) {
auto* region = m_impl->FindRegion(address);
if (region == nullptr) {
FailFast("backing write ended for an unknown page");
}
auto& page = m_impl->GetPage(*region, address);
SpinGuard lock(page.lock);
if (!page.resolving || page.backing_writer != writer) {
FailFast("backing write ended without matching owner and resolving state");
}
const auto old_protection = NO_ACCESS_PROTECTION;
const auto new_protection = Impl::WatcherProtection(page);
if (new_protection != old_protection) {
Impl::Protect(page, address, new_protection, old_protection, false);
}
Impl::PublishDelayedFaults(page, old_protection, new_protection);
if (page.write_watchers == 0 && page.access_watchers == 0) {
page.original_protection = 0;
}
page.backing_writer = 0;
page.resolving = false;
page.resolving_read_write = false;
}
}
bool PageManager::HandleFault(PageFaultAccess access, uint64_t fault_vaddr) noexcept {
if (g_in_fault_resolution) {
FailFast("nested HandleFault call");
}
auto* region = m_impl->FindRegion(fault_vaddr);
if (region == nullptr) {
return false;
}
auto& page = m_impl->GetPage(*region, fault_vaddr);
bool waited = false;
while (true) {
SpinGuard lock(page.lock);
if (access == PageFaultAccess::Read && page.late_read_pending &&
Impl::AllowsAccess(page, fault_vaddr, access)) {
page.late_read_pending = false;
return true;
}
if (access == PageFaultAccess::Write && page.late_write_pending &&
Impl::AllowsAccess(page, fault_vaddr, access)) {
page.late_write_pending = false;
return true;
}
if (page.resolving) {
if (page.backing_writer == CurrentThread()) {
FailFast("backing writer faulted on its own reserved page");
}
if ((!page.resolving_read_write && access != PageFaultAccess::Write) ||
(page.resolving_read_write && access != PageFaultAccess::Read &&
access != PageFaultAccess::Write)) {
FailFast("fault access is incompatible with the active resolver");
}
waited = true;
continue;
}
if (page.write_watchers == 0 && page.access_watchers == 0) {
if (access != PageFaultAccess::Read && access != PageFaultAccess::Write) {
return false;
}
bool& pending = (access == PageFaultAccess::Read ? page.late_read_pending
: page.late_write_pending);
const bool allowed = Impl::AllowsAccess(page, fault_vaddr, access);
pending = false;
if (waited && !allowed) {
FailFast("page remained inaccessible after waiting for its resolver");
}
// More than one CPU can fault before a protection transition becomes visible. The first
// delayed fault consumes the hint bit; later faults must also resume once the mapped
// page already permits the requested access. A genuinely read-only/no-access page still
// falls through to the guest exception path.
return allowed;
}
if ((access != PageFaultAccess::Read && access != PageFaultAccess::Write) ||
(access == PageFaultAccess::Read && page.access_watchers == 0)) {
FailFast("fault access is incompatible with active page watchers");
}
page.resolving = true;
page.resolving_read_write = page.access_watchers != 0;
break;
}
g_in_fault_resolution = true;
const bool handled = m_impl->fault_handler(m_impl->fault_context, access, fault_vaddr, 1,
PageFaultPhase::Invalidate);
g_in_fault_resolution = false;
{
SpinGuard lock(page.lock);
if (!handled || !page.resolving) {
FailFast("fault invalidation did not preserve the resolving state");
}
}
g_in_fault_resolution = true;
const bool completed = m_impl->fault_handler(m_impl->fault_context, access, fault_vaddr, 1,
PageFaultPhase::Complete);
g_in_fault_resolution = false;
{
SpinGuard lock(page.lock);
if (!completed || !page.resolving) {
FailFast("fault completion did not preserve the resolving state");
}
if (page.write_watchers != 0 || page.access_watchers != 0) {
const auto old_protection = Impl::WatcherProtection(page);
const bool read_only_fault = access == PageFaultAccess::Read;
if (read_only_fault && page.access_watchers == 0) {
FailFast("read fault completed without a read/write watcher");
}
page.access_watchers = 0;
if (!read_only_fault) {
page.write_watchers = 0;
}
const auto restored_protection = Impl::WatcherProtection(page);
Impl::Protect(page, PageStart(fault_vaddr), restored_protection, old_protection, true);
if (page.write_watchers == 0) {
page.original_protection = 0;
}
Impl::PublishDelayedFaults(page, old_protection, restored_protection);
} else if (!Impl::AllowsAccess(page, fault_vaddr, access)) {
FailFast("fault completion left the page inaccessible");
}
page.resolving = false;
page.resolving_read_write = false;
}
g_in_fault_resolution = true;
const bool released = m_impl->fault_handler(m_impl->fault_context, access, fault_vaddr, 1,
PageFaultPhase::Release);
g_in_fault_resolution = false;
if (!released) {
FailFast("fault release callback failed");
}
return true;
}
} // namespace Libs::Graphics
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