vm: use sigaltstack to handle callstack overflow properly

vm/os-genunix.cpp

@@ -9,7 +9,7 @@ void factor_vm::c_to_factor_toplevel(cell quot)
 	c_to_factor(quot);
 }
 
-void init_signals()
+void factor_vm::init_signals()
 {
 	unix_init_signals();
 }

vm/os-genunix.hpp

@@ -4,8 +4,6 @@ namespace factor
 #define VM_C_API extern "C"
 #define NULL_DLL NULL
 
-void c_to_factor_toplevel(cell quot);
-void init_signals();
 void early_init();
 const char *vm_executable_path();
 const char *default_image_path();

vm/os-macosx.hpp

@@ -5,14 +5,11 @@ namespace factor
 #define FACTOR_OS_STRING "macosx"
 #define NULL_DLL "libfactor.dylib"
 
-void init_signals();
 void early_init();
 
 const char *vm_executable_path();
 const char *default_image_path();
 
-void c_to_factor_toplevel(cell quot);
-
 #define UAP_STACK_POINTER(ucontext) (((ucontext_t *)ucontext)->uc_stack.ss_sp)
 
 #define UAP_STACK_POINTER_TYPE void*

vm/os-macosx.mm

@@ -70,7 +70,7 @@ const char *default_image_path(void)
 	return [returnVal UTF8String];
 }
 
-void init_signals(void)
+void factor_vm::init_signals(void)
 {
 	unix_init_signals();
 	mach_initialize();
@@ -87,11 +87,9 @@ Protocol *objc_getProtocol(char *name)
 
 u64 nano_count()
 {
-	u64 t;
+	u64 t = mach_absolute_time();
 	mach_timebase_info_data_t info;
-	kern_return_t ret;
+	kern_return_t ret = mach_timebase_info(&info);
-	t = mach_absolute_time();
-	ret = mach_timebase_info(&info);
 	if(ret != 0)
 		fatal_error("mach_timebase_info failed",ret);
 	return t * (info.numer/info.denom);

vm/os-unix.cpp

@@ -23,7 +23,6 @@ void init_platform_globals()
 {
 	if(pthread_key_create(&current_vm_tls_key, NULL) != 0)
 		fatal_error("pthread_key_create() failed",0);
-
 }
 
 void register_vm_with_thread(factor_vm *vm)
@@ -187,8 +186,18 @@ static void sigaction_safe(int signum, const struct sigaction *act, struct sigac
 		fatal_error("sigaction failed", 0);
 }
 
-void unix_init_signals()
+void factor_vm::unix_init_signals()
 {
+	signal_callstack_seg = new segment(callstack_size,false);
+
+	stack_t signal_callstack;
+	signal_callstack.ss_sp = (void *)signal_callstack_seg->start;
+	signal_callstack.ss_size = signal_callstack_seg->size;
+	signal_callstack.ss_flags = 0;
+
+	if(sigaltstack(&signal_callstack,(stack_t *)NULL) < 0)
+		fatal_error("sigaltstack() failed",0);
+
 	struct sigaction memory_sigaction;
 	struct sigaction misc_sigaction;
 	struct sigaction fpe_sigaction;
@@ -197,7 +206,7 @@ void unix_init_signals()
 	memset(&memory_sigaction,0,sizeof(struct sigaction));
 	sigemptyset(&memory_sigaction.sa_mask);
 	memory_sigaction.sa_sigaction = memory_signal_handler;
-	memory_sigaction.sa_flags = SA_SIGINFO;
+	memory_sigaction.sa_flags = SA_SIGINFO | SA_ONSTACK;
 
 	sigaction_safe(SIGBUS,&memory_sigaction,NULL);
 	sigaction_safe(SIGSEGV,&memory_sigaction,NULL);
@@ -205,14 +214,14 @@ void unix_init_signals()
 	memset(&fpe_sigaction,0,sizeof(struct sigaction));
 	sigemptyset(&fpe_sigaction.sa_mask);
 	fpe_sigaction.sa_sigaction = fpe_signal_handler;
-	fpe_sigaction.sa_flags = SA_SIGINFO;
+	fpe_sigaction.sa_flags = SA_SIGINFO | SA_ONSTACK;
 
 	sigaction_safe(SIGFPE,&fpe_sigaction,NULL);
 
 	memset(&misc_sigaction,0,sizeof(struct sigaction));
 	sigemptyset(&misc_sigaction.sa_mask);
 	misc_sigaction.sa_sigaction = misc_signal_handler;
-	misc_sigaction.sa_flags = SA_SIGINFO;
+	misc_sigaction.sa_flags = SA_SIGINFO | SA_ONSTACK;
 
 	sigaction_safe(SIGQUIT,&misc_sigaction,NULL);
 	sigaction_safe(SIGILL,&misc_sigaction,NULL);

vm/os-unix.hpp

@@ -39,7 +39,6 @@ typedef pthread_t THREADHANDLE;
 THREADHANDLE start_thread(void *(*start_routine)(void *),void *args);
 inline static THREADHANDLE thread_id() { return pthread_self(); }
 
-void unix_init_signals();
 void signal_handler(int signal, siginfo_t* siginfo, void* uap);
 void dump_stack_signal(int signal, siginfo_t* siginfo, void* uap);
 

vm/os-windows.cpp

@@ -143,4 +143,6 @@ void factor_vm::move_file(const vm_char *path1, const vm_char *path2)
 		general_error(ERROR_IO,tag_fixnum(GetLastError()),false_object);
 }
 
+void factor_vm::init_signals() {}
+
 }

vm/os-windows.hpp

@@ -43,7 +43,6 @@ typedef wchar_t vm_char;
 /* Difference between Jan 1 00:00:00 1601 and Jan 1 00:00:00 1970 */
 #define EPOCH_OFFSET 0x019db1ded53e8000LL
 
-inline static void init_signals() {}
 inline static void early_init() {}
 
 u64 system_micros();

vm/vm.cpp

@@ -13,7 +13,8 @@ factor_vm::factor_vm() :
 	gc_events(NULL),
 	fep_disabled(false),
 	full_output(false),
-	last_nano_count(0)
+	last_nano_count(0),
+	signal_callstack_seg(NULL)
 {
 	primitive_reset_dispatch_stats();
 }
@@ -21,6 +22,11 @@ factor_vm::factor_vm() :
 factor_vm::~factor_vm()
 {
 	delete_contexts();
+	if(signal_callstack_seg)
+	{
+		delete signal_callstack_seg;
+		signal_callstack_seg = NULL;
+	}
 }
 
 }

vm/vm.hpp

@@ -107,6 +107,9 @@ struct factor_vm
 	decrease */
 	u64 last_nano_count;
 
+	/* Stack for signal handlers, only used on Unix */
+	segment *signal_callstack_seg;
+
 	// contexts
 	context *new_context();
 	void delete_context(context *old_context);
@@ -685,6 +688,7 @@ struct factor_vm
 	void *ffi_dlsym(dll *dll, symbol_char *symbol);
 	void ffi_dlclose(dll *dll);
 	void c_to_factor_toplevel(cell quot);
+	void init_signals();
 
 	// os-windows
   #if defined(WINDOWS)
@@ -697,8 +701,10 @@ struct factor_vm
 	void open_console();
 	LONG exception_handler(PEXCEPTION_POINTERS pe);
   #endif
+
   #else  // UNIX
 	void dispatch_signal(void *uap, void (handler)());
+	void unix_init_signals();
   #endif
 
   #ifdef __APPLE__
@@ -707,7 +713,6 @@ struct factor_vm
 
 	factor_vm();
 	~factor_vm();
-
 };
 
 extern std::map<THREADHANDLE, factor_vm *> thread_vms;