Common: Add memory arena and page fault handler classes

src/common/CMakeLists.txt

@@ -54,6 +54,10 @@ add_library(common
   minizip_helpers.h
   null_audio_stream.cpp
   null_audio_stream.h
+  memory_arena.cpp
+  memory_arena.h
+  page_fault_handler.cpp
+  page_fault_handler.h
   rectangle.h
   progress_callback.cpp
   progress_callback.h
@@ -183,3 +187,8 @@ if(APPLE AND NOT BUILD_LIBRETRO_CORE)
     gl/context_agl.h
   )
 endif()
+
+if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+  # We need -lrt for shm_unlink
+  target_link_libraries(common PRIVATE rt)
+endif()

src/common/common.vcxproj

@@ -90,6 +90,8 @@
     <ClInclude Include="md5_digest.h" />
     <ClInclude Include="null_audio_stream.h" />
     <ClInclude Include="progress_callback.h" />
+    <ClInclude Include="memory_arena.h" />
+    <ClInclude Include="page_fault_handler.h" />
     <ClInclude Include="rectangle.h" />
     <ClInclude Include="cd_subchannel_replacement.h" />
     <ClInclude Include="scope_guard.h" />
@@ -154,6 +156,8 @@
     <ClCompile Include="null_audio_stream.cpp" />
     <ClCompile Include="progress_callback.cpp" />
     <ClCompile Include="shiftjis.cpp" />
+    <ClCompile Include="memory_arena.cpp" />
+    <ClCompile Include="page_fault_handler.cpp" />
     <ClCompile Include="state_wrapper.cpp" />
     <ClCompile Include="cd_xa.cpp" />
     <ClCompile Include="string.cpp" />

src/common/common.vcxproj.filters

@@ -102,6 +102,8 @@
     <ClInclude Include="win32_progress_callback.h" />
     <ClInclude Include="make_array.h" />
     <ClInclude Include="shiftjis.h" />
+    <ClInclude Include="memory_arena.h" />
+    <ClInclude Include="page_fault_handler.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="jit_code_buffer.cpp" />
@@ -196,6 +198,8 @@
     <ClCompile Include="minizip_helpers.cpp" />
     <ClCompile Include="win32_progress_callback.cpp" />
     <ClCompile Include="shiftjis.cpp" />
+    <ClCompile Include="memory_arena.cpp" />
+    <ClCompile Include="page_fault_handler.cpp" />
   </ItemGroup>
   <ItemGroup>
     <Natvis Include="bitfield.natvis" />

src/common/memory_arena.cpp

@@ -0,0 +1,294 @@
+#include "memory_arena.h"
+#include "common/assert.h"
+#include "common/log.h"
+#include "common/string_util.h"
+Log_SetChannel(Common::MemoryArena);
+
+#if defined(WIN32)
+#include "common/windows_headers.h"
+#elif defined(ANDROID)
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <linux/ashmem.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#elif defined(__linux__) || defined(__APPLE__)
+#include <cerrno>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#endif
+
+namespace Common {
+
+// Borrowed from Dolphin
+#ifdef ANDROID
+#define ASHMEM_DEVICE "/dev/ashmem"
+
+static int AshmemCreateFileMapping(const char* name, size_t size)
+{
+  // ASharedMemory path - works on API >= 26 and falls through on API < 26:
+
+  // We can't call ASharedMemory_create the normal way without increasing the
+  // minimum version requirement to API 26, so we use dlopen/dlsym instead
+  static void* libandroid = dlopen("libandroid.so", RTLD_LAZY | RTLD_LOCAL);
+  static auto shared_memory_create =
+    reinterpret_cast<int (*)(const char*, size_t)>(dlsym(libandroid, "ASharedMemory_create"));
+  if (shared_memory_create)
+    return shared_memory_create(name, size);
+
+  // /dev/ashmem path - works on API < 29:
+
+  int fd, ret;
+  fd = open(ASHMEM_DEVICE, O_RDWR);
+  if (fd < 0)
+    return fd;
+
+  // We don't really care if we can't set the name, it is optional
+  ioctl(fd, ASHMEM_SET_NAME, name);
+
+  ret = ioctl(fd, ASHMEM_SET_SIZE, size);
+  if (ret < 0)
+  {
+    close(fd);
+    Log_ErrorPrintf("Ashmem returned error: 0x%08x", ret);
+    return ret;
+  }
+  return fd;
+}
+#endif
+
+MemoryArena::MemoryArena() = default;
+
+MemoryArena::~MemoryArena()
+{
+#if defined(WIN32)
+  if (m_file_handle)
+    CloseHandle(m_file_handle);
+#elif defined(__linux__)
+  if (m_shmem_fd > 0)
+    close(m_shmem_fd);
+#endif
+}
+
+void* MemoryArena::FindBaseAddressForMapping(size_t size)
+{
+  void* base_address;
+#if defined(WIN32)
+  base_address = VirtualAlloc(nullptr, size, MEM_RESERVE, PAGE_READWRITE);
+  if (base_address)
+    VirtualFree(base_address, 0, MEM_RELEASE);
+#elif defined(__linux__) || defined(__APPLE__)
+  base_address = mmap(nullptr, size, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
+  if (base_address)
+    munmap(base_address, size);
+#elif defined(__ANDROID__)
+  base_address = mmap(nullptr, size, PROT_NONE, MAP_ANON | MAP_SHARED, -1, 0);
+  if (base_address)
+    munmap(base_address, size);
+#else
+  base_address = nullptr;
+#endif
+
+  if (!base_address)
+  {
+    Log_ErrorPrintf("Failed to get base address for memory mapping of size %zu", size);
+    return nullptr;
+  }
+
+  return base_address;
+}
+
+bool MemoryArena::Create(size_t size, bool writable, bool executable)
+{
+#if defined(WIN32)
+  const std::string file_mapping_name = StringUtil::StdStringFromFormat("duckstation_%u", GetCurrentProcessId());
+
+  const DWORD protect = (writable ? (executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE) : PAGE_READONLY);
+  m_file_handle = CreateFileMappingA(INVALID_HANDLE_VALUE, nullptr, protect, Truncate32(size >> 32), Truncate32(size),
+                                     file_mapping_name.c_str());
+  if (!m_file_handle)
+  {
+    Log_ErrorPrintf("CreateFileMapping failed: %u", GetLastError());
+    return false;
+  }
+
+  return true;
+#elif defined(ANDROID)
+  const std::string file_mapping_name =
+    StringUtil::StdStringFromFormat("duckstation_%u", static_cast<unsigned>(getpid()));
+  m_shmem_fd = AshmemCreateFileMapping(file_mapping_name.c_str(), size);
+  if (m_shmem_fd < 0)
+  {
+    Log_ErrorPrintf("AshmemCreateFileMapping failed: %d %d", m_shmem_fd, errno);
+    return false;
+  }
+
+  return true;
+#elif defined(__linux__)
+  const std::string file_mapping_name =
+    StringUtil::StdStringFromFormat("duckstation_%u", static_cast<unsigned>(getpid()));
+  m_shmem_fd = shm_open(file_mapping_name.c_str(), O_CREAT | O_EXCL | (writable ? O_RDWR : O_RDONLY), 0600);
+  if (m_shmem_fd < 0)
+  {
+    Log_ErrorPrintf("shm_open failed: %d", errno);
+    return false;
+  }
+
+  // we're not going to be opening this mapping in other processes, so remove the file
+  shm_unlink(file_mapping_name.c_str());
+
+  // ensure it's the correct size
+  if (ftruncate64(m_shmem_fd, static_cast<off64_t>(size)) < 0)
+  {
+    Log_ErrorPrintf("ftruncate64(%zu) failed: %d", size, errno);
+    return false;
+  }
+
+  return true;
+#elif defined(__APPLE__)
+  const std::string file_mapping_name =
+    StringUtil::StdStringFromFormat("duckstation_%u", static_cast<unsigned>(getpid()));
+  m_shmem_fd = shm_open(file_mapping_name.c_str(), O_CREAT | O_EXCL | (writable ? O_RDWR : O_RDONLY), 0600);
+  if (m_shmem_fd < 0)
+  {
+    Log_ErrorPrintf("shm_open failed: %d", errno);
+    return false;
+  }
+
+  // we're not going to be opening this mapping in other processes, so remove the file
+  shm_unlink(file_mapping_name.c_str());
+
+  // ensure it's the correct size
+  if (ftruncate(m_shmem_fd, static_cast<off_t>(size)) < 0)
+  {
+    Log_ErrorPrintf("ftruncate(%zu) failed: %d", size, errno);
+    return false;
+  }
+
+  return true;
+#else
+  return false;
+#endif
+}
+
+std::optional<MemoryArena::View> MemoryArena::CreateView(size_t offset, size_t size, bool writable, bool executable,
+                                                         void* fixed_address)
+{
+  void* base_pointer = CreateViewPtr(offset, size, writable, executable, fixed_address);
+  if (!base_pointer)
+    return std::nullopt;
+
+  return View(this, base_pointer, offset, size, writable);
+}
+
+void* MemoryArena::CreateViewPtr(size_t offset, size_t size, bool writable, bool executable,
+                                 void* fixed_address /*= nullptr*/)
+{
+  void* base_pointer;
+#if defined(WIN32)
+  const DWORD desired_access = FILE_MAP_READ | (writable ? FILE_MAP_WRITE : 0) | (executable ? FILE_MAP_EXECUTE : 0);
+  base_pointer =
+    MapViewOfFileEx(m_file_handle, desired_access, Truncate32(offset >> 32), Truncate32(offset), size, fixed_address);
+  if (!base_pointer)
+    return nullptr;
+#elif defined(__linux__)
+  const int flags = (fixed_address != nullptr) ? (MAP_SHARED | MAP_FIXED) : MAP_SHARED;
+  const int prot = PROT_READ | (writable ? PROT_WRITE : 0) | (executable ? PROT_EXEC : 0);
+  base_pointer = mmap64(fixed_address, size, prot, flags, m_shmem_fd, static_cast<off64_t>(offset));
+  if (base_pointer == reinterpret_cast<void*>(-1))
+    return nullptr;
+#elif defined(__APPLE__)
+  const int flags = (fixed_address != nullptr) ? (MAP_SHARED | MAP_FIXED) : MAP_SHARED;
+  const int prot = PROT_READ | (writable ? PROT_WRITE : 0) | (executable ? PROT_EXEC : 0);
+  base_pointer = mmap(fixed_address, size, prot, flags, m_shmem_fd, static_cast<off_t>(offset));
+  if (base_pointer == reinterpret_cast<void*>(-1))
+    return nullptr;
+#else
+  return nullptr;
+#endif
+
+  m_num_views.fetch_add(1);
+  return base_pointer;
+}
+
+bool MemoryArena::FlushViewPtr(void* address, size_t size)
+{
+#if defined(WIN32)
+  return FlushViewOfFile(address, size);
+#elif defined(__linux__) || defined(__APPLE__)
+  return (msync(address, size, 0) >= 0);
+#else
+  return false;
+#endif
+}
+
+bool MemoryArena::ReleaseViewPtr(void* address, size_t size)
+{
+  bool result;
+#if defined(WIN32)
+  result = static_cast<bool>(UnmapViewOfFile(address));
+#elif defined(__linux__) || defined(__APPLE__)
+  result = (munmap(address, size) >= 0);
+#else
+  result = false;
+#endif
+
+  if (!result)
+  {
+    Log_ErrorPrintf("Failed to unmap previously-created view at %p", address);
+    return false;
+  }
+
+  const size_t prev_count = m_num_views.fetch_sub(1);
+  Assert(prev_count > 0);
+  return true;
+}
+
+bool MemoryArena::SetPageProtection(void* address, size_t length, bool readable, bool writable, bool executable)
+{
+#if defined(WIN32)
+  static constexpr DWORD protection_table[2][2][2] = {
+    {{PAGE_NOACCESS, PAGE_EXECUTE}, {PAGE_WRITECOPY, PAGE_EXECUTE_WRITECOPY}},
+    {{PAGE_READONLY, PAGE_EXECUTE_READ}, {PAGE_READWRITE, PAGE_EXECUTE_READWRITE}}};
+
+  DWORD old_protect;
+  return static_cast<bool>(
+    VirtualProtect(address, length, protection_table[readable][writable][executable], &old_protect));
+#elif defined(__linux__) || defined(__ANDROID__) || defined(__APPLE__)
+  const int prot = (readable ? PROT_READ : 0) | (writable ? PROT_WRITE : 0) | (executable ? PROT_EXEC : 0);
+  return (mprotect(address, length, prot) >= 0);
+#else
+  return false;
+#endif
+}
+
+MemoryArena::View::View(MemoryArena* parent, void* base_pointer, size_t arena_offset, size_t mapping_size,
+                        bool writable)
+  : m_parent(parent), m_base_pointer(base_pointer), m_arena_offset(arena_offset), m_mapping_size(mapping_size),
+    m_writable(writable)
+{
+}
+
+MemoryArena::View::View(View&& view)
+  : m_parent(view.m_parent), m_base_pointer(view.m_base_pointer), m_arena_offset(view.m_arena_offset),
+    m_mapping_size(view.m_mapping_size)
+{
+  view.m_parent = nullptr;
+  view.m_base_pointer = nullptr;
+  view.m_arena_offset = 0;
+  view.m_mapping_size = 0;
+}
+
+MemoryArena::View::~View()
+{
+  if (m_parent)
+  {
+    if (m_writable && !m_parent->FlushViewPtr(m_base_pointer, m_mapping_size))
+      Panic("Failed to flush previously-created view");
+    if (!m_parent->ReleaseViewPtr(m_base_pointer, m_mapping_size))
+      Panic("Failed to unmap previously-created view");
+  }
+}
+} // namespace Common

src/common/memory_arena.h

@@ -0,0 +1,58 @@
+#pragma once
+#include "types.h"
+#include <atomic>
+#include <optional>
+
+namespace Common {
+class MemoryArena
+{
+public:
+  class View
+  {
+  public:
+    View(MemoryArena* parent, void* base_pointer, size_t arena_offset, size_t mapping_size, bool writable);
+    View(View&& view);
+    ~View();
+
+    void* GetBasePointer() const { return m_base_pointer; }
+    size_t GetArenaOffset() const { return m_arena_offset; }
+    size_t GetMappingSize() const { return m_mapping_size; }
+    bool IsWritable() const { return m_writable; }
+
+  private:
+    MemoryArena* m_parent;
+    void* m_base_pointer;
+    size_t m_arena_offset;
+    size_t m_mapping_size;
+    bool m_writable;
+  };
+
+  MemoryArena();
+  ~MemoryArena();
+
+  static void* FindBaseAddressForMapping(size_t size);
+
+  bool Create(size_t size, bool writable, bool executable);
+
+  std::optional<View> CreateView(size_t offset, size_t size, bool writable, bool executable,
+                                 void* fixed_address = nullptr);
+
+  void* CreateViewPtr(size_t offset, size_t size, bool writable, bool executable, void* fixed_address = nullptr);
+  bool FlushViewPtr(void* address, size_t size);
+  bool ReleaseViewPtr(void* address, size_t size);
+
+  static bool SetPageProtection(void* address, size_t length, bool readable, bool writable, bool executable);
+
+private:
+#if defined(WIN32)
+  void* m_file_handle = nullptr;
+#elif defined(__linux__) || defined(ANDROID) || defined(__APPLE__)
+  int m_shmem_fd = -1;
+#endif
+
+  std::atomic_size_t m_num_views{0};
+  size_t m_size = 0;
+  bool m_writable = false;
+  bool m_executable = false;
+};
+} // namespace Common

src/common/page_fault_handler.cpp

@@ -0,0 +1,275 @@
+#include "page_fault_handler.h"
+#include "common/log.h"
+#include <algorithm>
+#include <cstring>
+#include <mutex>
+Log_SetChannel(Common::PageFaultHandler);
+
+#if defined(WIN32)
+#include "common/windows_headers.h"
+#elif defined(__linux__) || defined(__ANDROID__)
+#include <signal.h>
+#include <ucontext.h>
+#include <unistd.h>
+#define USE_SIGSEGV 1
+#elif defined(__APPLE__)
+#include <signal.h>
+#include <unistd.h>
+#define USE_SIGSEGV 1
+#endif
+
+namespace Common::PageFaultHandler {
+
+struct RegisteredHandler
+{
+  void* owner;
+  Callback callback;
+};
+static std::vector<RegisteredHandler> m_handlers;
+static std::mutex m_handler_lock;
+static thread_local bool s_in_handler;
+
+#ifdef __aarch64__
+static bool IsStoreInstruction(const void* ptr)
+{
+  u32 bits;
+  std::memcpy(&bits, ptr, sizeof(bits));
+
+  // Based on vixl's disassembler Instruction::IsStore().
+  // if (Mask(LoadStoreAnyFMask) != LoadStoreAnyFixed)
+  if ((bits & 0x0a000000) != 0x08000000)
+    return false;
+
+  // if (Mask(LoadStorePairAnyFMask) == LoadStorePairAnyFixed)
+  if ((bits & 0x3a000000) == 0x28000000)
+  {
+    // return Mask(LoadStorePairLBit) == 0
+    return (bits & (1 << 22)) == 0;
+  }
+
+  switch (bits & 0xC4C00000)
+  {
+    case 0x00000000: // STRB_w
+    case 0x40000000: // STRH_w
+    case 0x80000000: // STR_w
+    case 0xC0000000: // STR_x
+    case 0x04000000: // STR_b
+    case 0x44000000: // STR_h
+    case 0x84000000: // STR_s
+    case 0xC4000000: // STR_d
+    case 0x04800000: // STR_q
+      return true;
+
+    default:
+      return false;
+  }
+}
+#endif
+
+#if defined(WIN32)
+static PVOID s_veh_handle;
+
+static LONG ExceptionHandler(PEXCEPTION_POINTERS exi)
+{
+  if (exi->ExceptionRecord->ExceptionCode != EXCEPTION_ACCESS_VIOLATION || s_in_handler)
+    return EXCEPTION_CONTINUE_SEARCH;
+
+  s_in_handler = true;
+
+#if defined(_M_AMD64)
+  void* const exception_pc = reinterpret_cast<void*>(exi->ContextRecord->Rip);
+#elif defined(_M_ARM64)
+  void* const exception_pc = reinterpret_cast<void*>(exi->ContextRecord->Pc);
+#else
+  void* const exception_pc = nullptr;
+#endif
+
+  void* const exception_address = reinterpret_cast<void*>(exi->ExceptionRecord->ExceptionInformation[1]);
+  bool const is_write = exi->ExceptionRecord->ExceptionInformation[0] == 1;
+
+  std::lock_guard<std::mutex> guard(m_handler_lock);
+  for (const RegisteredHandler& rh : m_handlers)
+  {
+    if (rh.callback(exception_pc, exception_address, is_write) == HandlerResult::ContinueExecution)
+    {
+      s_in_handler = false;
+      return EXCEPTION_CONTINUE_EXECUTION;
+    }
+  }
+
+  s_in_handler = false;
+  return EXCEPTION_CONTINUE_SEARCH;
+}
+
+#elif defined(USE_SIGSEGV)
+
+static struct sigaction s_old_sigsegv_action;
+#ifdef __APPLE__
+static struct sigaction s_old_sigbus_action;
+#endif
+
+static void SIGSEGVHandler(int sig, siginfo_t* info, void* ctx)
+{
+  if ((info->si_code != SEGV_MAPERR && info->si_code != SEGV_ACCERR) || s_in_handler)
+    return;
+
+#ifndef __APPLE__
+  void* const exception_address = reinterpret_cast<void*>(info->si_addr);
+
+#if defined(__x86_64__)
+  void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_RIP]);
+  const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_ERR] & 2) != 0;
+#elif defined(__aarch64__)
+  void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.pc);
+  const bool is_write = IsStoreInstruction(exception_pc);
+#else
+  void* const exception_pc = nullptr;
+  const bool is_write = false;
+#endif
+#else // __APPLE__
+#if defined(__x86_64__)
+  void* const exception_address =
+    reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__faultvaddr);
+  void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__rip);
+  const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__err & 2) != 0;
+#elif defined(__aarch64__)
+  void* const exception_address = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__far);
+  void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__pc);
+  const bool is_write = IsStoreInstruction(exception_pc);
+#else
+  void* const exception_address = reinterpret_cast<void*>(info->si_addr);
+  void* const exception_pc = nullptr;
+  const bool is_write = false;
+#endif
+#endif // __APPLE__
+
+  std::lock_guard<std::mutex> guard(m_handler_lock);
+  for (const RegisteredHandler& rh : m_handlers)
+  {
+    if (rh.callback(exception_pc, exception_address, is_write) == HandlerResult::ContinueExecution)
+    {
+      s_in_handler = false;
+      return;
+    }
+  }
+
+  // call old signal handler
+#ifndef __APPLE__
+  const struct sigaction& sa = s_old_sigsegv_action;
+#else
+  const struct sigaction& sa = (sig == SIGBUS) ? s_old_sigbus_action : s_old_sigsegv_action;
+#endif
+  if (sa.sa_flags & SA_SIGINFO)
+    sa.sa_sigaction(sig, info, ctx);
+  else if (sa.sa_handler == SIG_DFL)
+    signal(sig, SIG_DFL);
+  else if (sa.sa_handler == SIG_IGN)
+    return;
+  else
+    sa.sa_handler(sig);
+}
+
+#endif
+
+bool InstallHandler(void* owner, Callback callback)
+{
+  bool was_empty;
+  {
+    std::lock_guard<std::mutex> guard(m_handler_lock);
+    if (std::find_if(m_handlers.begin(), m_handlers.end(),
+                     [owner](const RegisteredHandler& rh) { return rh.owner == owner; }) != m_handlers.end())
+    {
+      return false;
+    }
+
+    was_empty = m_handlers.empty();
+    m_handlers.push_back(RegisteredHandler{owner, std::move(callback)});
+  }
+
+  if (was_empty)
+  {
+#if defined(WIN32)
+    s_veh_handle = AddVectoredExceptionHandler(1, ExceptionHandler);
+    if (!s_veh_handle)
+    {
+      Log_ErrorPrint("Failed to add vectored exception handler");
+      return false;
+    }
+#elif defined(USE_SIGSEGV)
+#if 0
+    // Alternative stack - we'll need this is we ever use the host stack for branches.
+    stack_t signal_stack = {};
+    signal_stack.ss_sp = malloc(SIGSTKSZ);
+    signal_stack.ss_size = SIGSTKSZ;
+    if (sigaltstack(&signal_stack, nullptr))
+    {
+      Log_ErrorPrintf("signaltstack() failed: %d", errno);
+      return false;
+    }
+#endif
+
+    struct sigaction sa = {};
+    sa.sa_sigaction = SIGSEGVHandler;
+    sa.sa_flags = SA_SIGINFO;
+    sigemptyset(&sa.sa_mask);
+    if (sigaction(SIGSEGV, &sa, &s_old_sigsegv_action) < 0)
+    {
+      Log_ErrorPrintf("sigaction(SIGSEGV) failed: %d", errno);
+      return false;
+    }
+#ifdef __APPLE__
+    if (sigaction(SIGBUS, &sa, &s_old_sigbus_action) < 0)
+    {
+      Log_ErrorPrintf("sigaction(SIGBUS) failed: %d", errno);
+      return false;
+    }
+#endif
+
+#else
+    return false;
+#endif
+  }
+
+  return true;
+}
+
+bool RemoveHandler(void* owner)
+{
+  std::lock_guard<std::mutex> guard(m_handler_lock);
+  auto it = std::find_if(m_handlers.begin(), m_handlers.end(),
+                         [owner](const RegisteredHandler& rh) { return rh.owner == owner; });
+  if (it == m_handlers.end())
+    return false;
+
+  m_handlers.erase(it);
+
+  if (m_handlers.empty())
+  {
+#if defined(WIN32)
+    RemoveVectoredExceptionHandler(s_veh_handle);
+    s_veh_handle = nullptr;
+#else
+    // restore old signal handler
+#ifdef __APPLE__
+    if (sigaction(SIGBUS, &s_old_sigbus_action, nullptr) < 0)
+    {
+      Log_ErrorPrintf("sigaction(SIGBUS) failed: %d", errno);
+      return false;
+    }
+    s_old_sigbus_action = {};
+#endif
+
+    if (sigaction(SIGSEGV, &s_old_sigsegv_action, nullptr) < 0)
+    {
+      Log_ErrorPrintf("sigaction(SIGSEGV) failed: %d", errno);
+      return false;
+    }
+
+    s_old_sigsegv_action = {};
+#endif
+  }
+
+  return true;
+}
+
+} // namespace Common::PageFaultHandler

src/common/page_fault_handler.h

@@ -0,0 +1,18 @@
+#pragma once
+#include "types.h"
+#include <functional>
+
+namespace Common::PageFaultHandler {
+enum class HandlerResult
+{
+  ContinueExecution,
+  ExecuteNextHandler,
+};
+
+using Callback = std::function<HandlerResult(void* exception_pc, void* fault_address, bool is_write)>;
+using Handle = void*;
+
+bool InstallHandler(void* owner, Callback callback);
+bool RemoveHandler(void* owner);
+
+} // namespace Common::PageFaultHandler