Linux: port the emulator to a working state on Linux (#117)

Linux: port the emulator to a working state
2026-10-20 19:07:01 +02:00 · 2026-07-29 01:25:58 +03:00
parent 3dc793d859
commit 2b9cba457e
30 changed files with 2320 additions and 381 deletions
@@ -25,6 +25,14 @@
 #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 {
@@ -83,6 +91,9 @@ static uint32_t MachQueryPageProt(uint64_t vaddr) {
 	}
 	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;
@@ -101,6 +112,10 @@ thread_local bool g_in_fault_resolution = false;
 		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
@@ -125,11 +140,134 @@ uint32_t CurrentThread() noexcept {
 	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();
+	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);
+	}
+}
+
+// Async-signal-safe lookup in the address-ordered /proc/self/maps.
+uint32_t QueryHostProtection(uint64_t vaddr) noexcept {
+	int fd = ::open("/proc/self/maps", O_RDONLY | O_CLOEXEC); // NOLINT
+	if (fd < 0) {
+		return UNKNOWN_PROTECTION;
+	}
+
+	enum class Field { Start, End, Perms, Rest };
+
+	uint32_t result     = UNKNOWN_PROTECTION;
+	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 = 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;
+}
+#endif
+
 class SpinGuard final {
 public:
 	explicit SpinGuard(std::atomic_flag& lock): m_lock(lock) {
@@ -171,6 +309,10 @@ struct PageManager::Impl {
 		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;
@@ -199,7 +341,10 @@ struct PageManager::Impl {
 			      static_cast<uint32_t>(getpagesize()));
 		}
 #else
-		Fatal("page-fault invalidation is not implemented on this platform");
+		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++) {
@@ -267,7 +412,7 @@ struct PageManager::Impl {
 		}
 	}

-	static uint32_t QueryProtection(uint64_t vaddr) {
+	static uint32_t QueryProtection([[maybe_unused]] PageState& page, uint64_t vaddr) {
 #if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
 		MEMORY_BASIC_INFORMATION info {};
 		if (VirtualQuery(reinterpret_cast<const void*>(static_cast<uintptr_t>(vaddr)), &info,
@@ -287,12 +432,19 @@ struct PageManager::Impl {
 		}
 		return protection;
 #else
-		(void)vaddr;
-		Fatal("page query is unsupported on this platform");
+		const auto host_protection = QueryHostProtection(vaddr);
+		if (host_protection != READ_WRITE_PROTECTION) {
+			Fatal("basic path requires a read/write mapping at 0x%016" PRIx64
+			      " (protection=0x%08" PRIx32 ")",
+			      vaddr, host_protection);
+		}
+		page.current_protection = host_protection;
+		return host_protection;
 #endif
 	}

-	static bool AllowsAccess(uint64_t vaddr, PageFaultAccess access) noexcept {
+	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,
@@ -315,13 +467,24 @@ struct PageManager::Impl {
 			default: return false;
 		}
 #else
-		(void)vaddr;
-		return false;
+		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 Protect(uint64_t vaddr, uint32_t protection, uint32_t expected_old,
-	                    bool fault_path) noexcept {
+	static void Protect([[maybe_unused]] PageState& page, uint64_t vaddr, uint32_t protection,
+	                    uint32_t expected_old, bool fault_path) noexcept {
 #if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
 		DWORD old_protection = 0;
 		if (VirtualProtect(reinterpret_cast<void*>(static_cast<uintptr_t>(vaddr)), PAGE_SIZE,
@@ -347,10 +510,24 @@ struct PageManager::Impl {
 			Fatal("mprotect failed at 0x%016" PRIx64 ", new=0x%08" PRIx32, vaddr, protection);
 		}
 #else
-		(void)vaddr;
-		(void)protection;
-		(void)fault_path;
-		FailFast("page protection is unsupported on this platform");
+		if (page.current_protection != UNKNOWN_PROTECTION &&
+		    page.current_protection != expected_old) {
+			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, page.current_protection, expected_old, protection);
+		}
+		if (::mprotect(reinterpret_cast<void*>(static_cast<uintptr_t>(vaddr)), PAGE_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));
+		}
+		page.current_protection = protection;
 #endif
 	}

@@ -480,13 +657,13 @@ void PageManager::UpdatePageWatchers(bool track, uint64_t vaddr, uint64_t size,
 			}
 			const bool first_watcher = page.write_watchers == 0 && page.access_watchers == 0;
 			if (first_watcher) {
-				page.original_protection = Impl::QueryProtection(page_vaddr);
+				page.original_protection = Impl::QueryProtection(page, page_vaddr);
 			}
 			const auto old_protection = Impl::WatcherProtection(page);
 			watchers++;
 			const auto new_protection = Impl::WatcherProtection(page);
 			if (new_protection != old_protection) {
-				Impl::Protect(page_vaddr, new_protection, old_protection, false);
+				Impl::Protect(page, page_vaddr, new_protection, old_protection, false);
 			}
 			switch (new_protection) {
 				case NO_ACCESS_PROTECTION:
@@ -507,7 +684,7 @@ void PageManager::UpdatePageWatchers(bool track, uint64_t vaddr, uint64_t size,
 			watchers--;
 			const auto new_protection = Impl::WatcherProtection(page);
 			if (page.backing_writer == 0 && new_protection != old_protection) {
-				Impl::Protect(page_vaddr, new_protection, old_protection, false);
+				Impl::Protect(page, page_vaddr, new_protection, old_protection, false);
 			}
 			if (page.backing_writer == 0) {
 				Impl::PublishDelayedFaults(page, old_protection, new_protection);
@@ -540,6 +717,12 @@ void PageManager::OnGpuMap(uint64_t vaddr, uint64_t size, GpuAccess access) {
 		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
 	}
 }

@@ -661,7 +844,7 @@ void PageManager::EndBackingWrite(uint64_t vaddr, uint64_t size) noexcept {
 		const auto old_protection = NO_ACCESS_PROTECTION;
 		const auto new_protection = Impl::WatcherProtection(page);
 		if (new_protection != old_protection) {
-			Impl::Protect(address, new_protection, old_protection, false);
+			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) {
@@ -686,12 +869,12 @@ bool PageManager::HandleFault(PageFaultAccess access, uint64_t fault_vaddr) noex
 	while (true) {
 		SpinGuard lock(page.lock);
 		if (access == PageFaultAccess::Read && page.late_read_pending &&
-		    Impl::AllowsAccess(fault_vaddr, access)) {
+		    Impl::AllowsAccess(page, fault_vaddr, access)) {
 			page.late_read_pending = false;
 			return true;
 		}
 		if (access == PageFaultAccess::Write && page.late_write_pending &&
-		    Impl::AllowsAccess(fault_vaddr, access)) {
+		    Impl::AllowsAccess(page, fault_vaddr, access)) {
 			page.late_write_pending = false;
 			return true;
 		}
@@ -713,7 +896,7 @@ bool PageManager::HandleFault(PageFaultAccess access, uint64_t fault_vaddr) noex
 			}
 			bool&      pending = (access == PageFaultAccess::Read ? page.late_read_pending
 			                                                      : page.late_write_pending);
-			const bool allowed = Impl::AllowsAccess(fault_vaddr, access);
+			const bool allowed = Impl::AllowsAccess(page, fault_vaddr, access);
 			pending            = false;
 			if (waited && !allowed) {
 				FailFast("page remained inaccessible after waiting for its resolver");
@@ -762,12 +945,12 @@ bool PageManager::HandleFault(PageFaultAccess access, uint64_t fault_vaddr) noex
 				page.write_watchers = 0;
 			}
 			const auto restored_protection = Impl::WatcherProtection(page);
-			Impl::Protect(PageStart(fault_vaddr), restored_protection, old_protection, true);
+			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(fault_vaddr, access)) {
+		} else if (!Impl::AllowsAccess(page, fault_vaddr, access)) {
 			FailFast("fault completion left the page inaccessible");
 		}
 		page.resolving            = false;
@@ -18,6 +18,9 @@
 #undef max
 #elif defined(__APPLE__)
 #include <pthread.h>
+#elif defined(__linux__)
+#include <sys/syscall.h>
+#include <unistd.h>
 #endif

 namespace Libs::Graphics {
@@ -54,6 +57,9 @@ private:
 #elif defined(__APPLE__)
 		// mach thread port is a nonzero per-thread id (0 is the "no owner" sentinel).
 		return static_cast<uint32_t>(pthread_mach_thread_np(pthread_self()));
+#elif defined(__linux__)
+		static thread_local const uint32_t tid = static_cast<uint32_t>(::syscall(SYS_gettid));
+		return tid;
 #else
 		EXIT("region tracking thread identity is unsupported on this platform\n");
 #endif
@@ -19,12 +19,16 @@
 #include <windows.h>
 #undef min
 #undef max
+#else
+#include <dlfcn.h>
+
+// RenderDoc uses Windows-style names in its cross-platform API.
+#define __cdecl
+using HMODULE = void*;
 #endif

 namespace Libs::Graphics {

-#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
-
 using RenderDocDevicePointer = void*;
 using RenderDocWindowHandle  = void*;

@@ -107,6 +111,8 @@ static RenderDocDevicePointer GetRenderDocDevicePointer(vk::Instance instance) {
 	return VulkanHandleToPointer(instance);
 }

+#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
+
 static bool BindRenderDocApi(HMODULE module) {
 	auto* get_api = reinterpret_cast<pRENDERDOC_GetAPI>(GetProcAddress(module, "RENDERDOC_GetAPI"));
 	if (get_api == nullptr) {
@@ -147,10 +153,84 @@ static RenderDocWindowHandle GetRenderDocWindowHandle(SDL_Window* window) {
 	return info.info.win.window;
 }

+#else
+
+static bool BindRenderDocApi(HMODULE module) {
+	auto* get_api = reinterpret_cast<pRENDERDOC_GetAPI>(::dlsym(module, "RENDERDOC_GetAPI"));
+	if (get_api == nullptr) {
+		return false;
+	}
+
+	void* api = nullptr;
+	if (get_api(eRENDERDOC_API_Version_1_4_2, &api) == 0 || api == nullptr) {
+		return false;
+	}
+
+	g_module = module;
+	g_api    = static_cast<RenderDocApi*>(api);
+
+	g_api->SetCaptureFilePathTemplate("_RenderDoc/kyty");
+	static RenderDocInputButton capture_keys[] = {eRENDERDOC_Key_F1};
+	g_api->SetCaptureKeys(capture_keys, 1);
+	g_api->UnloadCrashHandler();
+
+	Dl_info info {};
+	if (::dladdr(reinterpret_cast<void*>(get_api), &info) != 0 && info.dli_fname != nullptr) {
+		LOGF("RenderDoc: bound API from %s\n", info.dli_fname);
+	} else {
+		LOGF("RenderDoc: bound API\n");
+	}
+	return true;
+}
+
+static RenderDocWindowHandle GetRenderDocWindowHandle(SDL_Window* window) {
+	if (window == nullptr) {
+		return nullptr;
+	}
+
+	SDL_SysWMinfo info {};
+	SDL_VERSION(&info.version);
+
+	if (SDL_GetWindowWMInfo(window, &info) != SDL_TRUE) {
+		return nullptr;
+	}
+
+#if defined(SDL_VIDEO_DRIVER_X11)
+	if (info.subsystem == SDL_SYSWM_X11) {
+		// RenderDoc takes the raw xlib Window id in the pointer slot, not a Display*.
+		return reinterpret_cast<RenderDocWindowHandle>(
+		    static_cast<uintptr_t>(info.info.x11.window));
+	}
+#endif
+
+	// Wayland capture works without an active-window handle.
+	static std::atomic_bool logged = false;
+	if (!logged.exchange(true)) {
+		LOGF("RenderDoc: no native window handle for SDL subsystem %d (Wayland?); the in-app "
+		     "overlay is unavailable, but --rd captures still work\n",
+		     static_cast<int>(info.subsystem));
+	}
+	return nullptr;
+}
+
+#endif
+
+#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
+
 static bool IsAvailable() {
 	return g_api != nullptr && g_device != nullptr && g_window != nullptr;
 }

+#else
+
+static bool IsAvailable() {
+	return g_api != nullptr && g_device != nullptr;
+}
+
+#endif
+
+#if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
+
 void RenderDocInit() {
 	bool expected = false;
 	if (!g_init_done.compare_exchange_strong(expected, true)) {
@@ -187,6 +267,33 @@ void RenderDocInit() {
 	}
 }

+#else
+
+void RenderDocInit() {
+	bool expected = false;
+	if (!g_init_done.compare_exchange_strong(expected, true)) {
+		return;
+	}
+
+	// Prefer an injected RenderDoc instance.
+	auto* module = ::dlopen("librenderdoc.so", RTLD_NOW | RTLD_NOLOAD);
+	if (module == nullptr) {
+		module = ::dlopen("librenderdoc.so", RTLD_NOW);
+	}
+	if (module == nullptr) {
+		LOGF("RenderDoc: librenderdoc.so was not found; in-app capture disabled\n");
+		return;
+	}
+
+	if (!BindRenderDocApi(module)) {
+		LOGF("RenderDoc: API 1.4.2 is not available; in-app capture disabled\n");
+		::dlclose(module);
+		return;
+	}
+}
+
+#endif
+
 void RenderDocSetActiveWindow(vk::Instance instance, SDL_Window* window) {
 	if (g_api == nullptr) {
 		return;
@@ -274,13 +381,4 @@ void RenderDocOnPresent() {
 	}
 }

-#else
-
-void RenderDocInit() {}
-void RenderDocSetActiveWindow(vk::Instance /*instance*/, SDL_Window* /*window*/) {}
-void RenderDocRequestCapture() {}
-void RenderDocOnPresent() {}
-
-#endif
-
 } // namespace Libs::Graphics