Fix macOS guest address-space reservation

src/common/hostException.cpp

@@ -324,10 +324,6 @@ bool InstallHandler(Handler handler) {
 	sa.sa_sigaction = SignalHandler;
 	sa.sa_flags     = SA_SIGINFO;
 	sigemptyset(&sa.sa_mask);
-	// The guest signal-dispatch path (KernelRaiseException) interrupts threads with
-	// SIGUSR1; block it while a fault is being resolved so a stop-the-world request
-	// cannot preempt the handler between the protection fix and the retry.
-	sigaddset(&sa.sa_mask, SIGUSR1);
 
 	// macOS raises SIGBUS for protection faults on some paths and SIGSEGV on others;
 	// SIGILL covers instructions the host cannot execute (routed to the x64 emulator).

src/libs/libKernel.cpp

@@ -40,10 +40,7 @@
 #define NOMINMAX
 #endif
 #include <windows.h>
-#elif defined(__APPLE__)
-#include <csignal>
-#include <sys/ucontext.h>
-#else
+#elif !defined(__APPLE__)
 #include <csignal>
 #include <ucontext.h>
 #endif
@@ -840,7 +837,7 @@ static void ApplySignalUcontext(CONTEXT* dst_ctx, const SignalUcontext& src_ctx)
 }
 #endif
 
-#if KYTY_PLATFORM != KYTY_PLATFORM_WINDOWS && defined(__x86_64__)
+#if KYTY_PLATFORM != KYTY_PLATFORM_WINDOWS && !defined(__APPLE__) && defined(__x86_64__)
 
 static SignalUcontext CreateSignalUcontextFromHost(const ucontext_t* host_ctx) {
 	SignalUcontext ctx = {};
@@ -848,34 +845,6 @@ static SignalUcontext CreateSignalUcontextFromHost(const ucontext_t* host_ctx) {
 		return ctx;
 	}
 
-#if defined(__APPLE__)
-	const auto& ss = host_ctx->uc_mcontext->__ss;
-
-	ctx.uc_mcontext.mc_rdi    = ss.__rdi;
-	ctx.uc_mcontext.mc_rsi    = ss.__rsi;
-	ctx.uc_mcontext.mc_rdx    = ss.__rdx;
-	ctx.uc_mcontext.mc_rcx    = ss.__rcx;
-	ctx.uc_mcontext.mc_r8     = ss.__r8;
-	ctx.uc_mcontext.mc_r9     = ss.__r9;
-	ctx.uc_mcontext.mc_rax    = ss.__rax;
-	ctx.uc_mcontext.mc_rbx    = ss.__rbx;
-	ctx.uc_mcontext.mc_rbp    = ss.__rbp;
-	ctx.uc_mcontext.mc_r10    = ss.__r10;
-	ctx.uc_mcontext.mc_r11    = ss.__r11;
-	ctx.uc_mcontext.mc_r12    = ss.__r12;
-	ctx.uc_mcontext.mc_r13    = ss.__r13;
-	ctx.uc_mcontext.mc_r14    = ss.__r14;
-	ctx.uc_mcontext.mc_r15    = ss.__r15;
-	ctx.uc_mcontext.mc_rip    = ss.__rip;
-	ctx.uc_mcontext.mc_rsp    = ss.__rsp;
-	ctx.uc_mcontext.mc_rflags = ss.__rflags;
-	ctx.uc_mcontext.mc_cs     = ss.__cs & 0xffffu;
-	ctx.uc_mcontext.mc_gs     = static_cast<uint16_t>(ss.__gs & 0xffffu);
-	ctx.uc_mcontext.mc_fs     = static_cast<uint16_t>(ss.__fs & 0xffffu);
-	ctx.uc_mcontext.mc_len    = sizeof(SignalMcontext);
-
-	return ctx;
-#else
 	const auto* gregs = host_ctx->uc_mcontext.gregs;
 
 	ctx.uc_mcontext.mc_rdi    = static_cast<uint64_t>(gregs[REG_RDI]);
@@ -905,7 +874,6 @@ static SignalUcontext CreateSignalUcontextFromHost(const ucontext_t* host_ctx) {
 	ctx.uc_mcontext.mc_len = sizeof(SignalMcontext);
 
 	return ctx;
-#endif
 }
 
 static void ApplySignalUcontextToHost(ucontext_t* dst_ctx, const SignalUcontext& src_ctx) {
@@ -913,29 +881,6 @@ static void ApplySignalUcontextToHost(ucontext_t* dst_ctx, const SignalUcontext&
 		return;
 	}
 
-#if defined(__APPLE__)
-	auto& ss = dst_ctx->uc_mcontext->__ss;
-
-	ss.__rdi    = src_ctx.uc_mcontext.mc_rdi;
-	ss.__rsi    = src_ctx.uc_mcontext.mc_rsi;
-	ss.__rdx    = src_ctx.uc_mcontext.mc_rdx;
-	ss.__rcx    = src_ctx.uc_mcontext.mc_rcx;
-	ss.__r8     = src_ctx.uc_mcontext.mc_r8;
-	ss.__r9     = src_ctx.uc_mcontext.mc_r9;
-	ss.__rax    = src_ctx.uc_mcontext.mc_rax;
-	ss.__rbx    = src_ctx.uc_mcontext.mc_rbx;
-	ss.__rbp    = src_ctx.uc_mcontext.mc_rbp;
-	ss.__r10    = src_ctx.uc_mcontext.mc_r10;
-	ss.__r11    = src_ctx.uc_mcontext.mc_r11;
-	ss.__r12    = src_ctx.uc_mcontext.mc_r12;
-	ss.__r13    = src_ctx.uc_mcontext.mc_r13;
-	ss.__r14    = src_ctx.uc_mcontext.mc_r14;
-	ss.__r15    = src_ctx.uc_mcontext.mc_r15;
-	ss.__rip    = src_ctx.uc_mcontext.mc_rip;
-	ss.__rsp    = src_ctx.uc_mcontext.mc_rsp;
-	ss.__rflags = src_ctx.uc_mcontext.mc_rflags;
-	// Segment selectors are left untouched; XNU validates them on sigreturn.
-#else
 	auto* gregs = dst_ctx->uc_mcontext.gregs;
 
 	gregs[REG_RDI] = static_cast<greg_t>(src_ctx.uc_mcontext.mc_rdi);
@@ -958,17 +903,10 @@ static void ApplySignalUcontextToHost(ucontext_t* dst_ctx, const SignalUcontext&
 	gregs[REG_EFL] = static_cast<greg_t>(src_ctx.uc_mcontext.mc_rflags);
 
 	// The kernel validates packed segment selectors on sigreturn.
-#endif
 }
 
 static int SignalDispatchHostSignal() {
-#if defined(__APPLE__)
-	// macOS has no realtime signals; SIGUSR1 is otherwise unused on the host side (the
-	// guest's SIGUSR1 is an emulated signal number, not a host registration).
-	static const int host_signal = SIGUSR1;
-#else
 	static const int host_signal = SIGRTMIN + 3;
-#endif
 	return host_signal;
 }
 
@@ -1236,7 +1174,7 @@ static int KYTY_SYSV_ABI KernelRaiseException(Pthread thread, int signum) {
 		}
 		CloseHandle(target_thread);
 		return OK;
-#elif defined(__x86_64__)
+#elif !defined(__APPLE__) && defined(__x86_64__)
 		// Deliver on the target thread.
 		if (thread == PthreadSelfOrNull()) {
 			SignalDispatchScope scope;