Remove HAVE_WORKING_SIGALTSTACK

Not enabled in dotnet/runtime since the beginning.
It was also making crashes harder to investigate because we wouldn't get "normal" stack traces that GDB could understand.

Author: akoeplinger

src/mono/cmake/config.h.in

@@ -536,9 +536,6 @@
    and to 0 if you don't. */
 #cmakedefine HAVE_DECL_PTHREAD_MUTEXATTR_SETPROTOCOL 1
 
-/* Have a working sigaltstack */
-#cmakedefine HAVE_WORKING_SIGALTSTACK 1
-
 /* Define to 1 if you have the `shm_open' function. */
 #cmakedefine HAVE_SHM_OPEN 1
 

src/mono/mono.proj

@@ -378,7 +378,6 @@
       <_MonoCMakeArgs Include="-DENABLE_MINIMAL=jit,logging,shared_perfcounters" />
       <_MonoCMakeArgs Include="-DENABLE_VISIBILITY_HIDDEN=1"/>
       <_MonoCMakeArgs Include="-DENABLE_LAZY_GC_THREAD_CREATION=1"/>
-      <_MonoCMakeArgs Include="-DENABLE_SIGALTSTACK=0"/>
       <_MonoCMakeArgs Include="-DENABLE_ICALL_EXPORT=1"/>
       <_MonoCFLAGS Include="-Werror=partial-availability" />
       <_MonoCFLAGS Condition="'$(TargetstvOS)' == 'true'" Include="-fno-gnu-inline-asm" />
@@ -406,7 +405,6 @@
       <_MonoCMakeArgs Condition="'$(Platform)' == 'x86'" Include="-DANDROID_ABI=x86" />
       <_MonoCMakeArgs Condition="'$(Platform)' == 'x64'" Include="-DANDROID_ABI=x86_64" />
       <_MonoCMakeArgs Include="-DENABLE_MINIMAL=ssa,logging" />
-      <_MonoCMakeArgs Include="-DENABLE_SIGALTSTACK=1"/>
 
       <_MonoCFLAGS Condition="'$(Platform)' == 'arm'" Include="-march=armv7-a" />
       <_MonoCFLAGS Condition="'$(Platform)' == 'arm'" Include="-mtune=cortex-a8" />

src/mono/mono/component/debugger-agent.c

@@ -4316,7 +4316,6 @@ resume_from_signal_handler (void *sigctx, void *func)
 	MonoContext ctx;
 
 	/* Save the original context in TLS */
-	// FIXME: This might not work on an altstack ?
 	tls = (DebuggerTlsData *)mono_native_tls_get_value (debugger_tls_id);
 	if (!tls)
 		PRINT_ERROR_MSG ("Thread %p is not attached to the JIT.\n", (gpointer) (gsize) mono_native_thread_id_get ());

src/mono/mono/metadata/boehm-gc.c

@@ -1204,18 +1204,6 @@ mono_gc_get_vtable_bits (MonoClass *klass)
 	return 0;
 }
 
-/*
- * mono_gc_register_altstack:
- *
- *   Register the dimensions of the normal stack and altstack with the collector.
- * Currently, STACK/STACK_SIZE is only used when the thread is suspended while it is on an altstack.
- */
-void
-mono_gc_register_altstack (gpointer stack, gint32 stack_size, gpointer altstack, gint32 altstack_size)
-{
-	GC_register_altstack (stack, stack_size, altstack, altstack_size);
-}
-
 int
 mono_gc_get_los_limit (void)
 {

src/mono/mono/metadata/gc-internals.h

@@ -406,8 +406,6 @@ MonoVTable *mono_gc_get_vtable (MonoObject *obj);
 
 guint mono_gc_get_vtable_bits (MonoClass *klass);
 
-void mono_gc_register_altstack (gpointer stack, gint32 stack_size, gpointer altstack, gint32 altstack_size);
-
 gboolean mono_gc_is_critical_method (MonoMethod *method);
 
 G_EXTERN_C // due to THREAD_INFO_TYPE varying

src/mono/mono/metadata/null-gc.c

@@ -606,11 +606,6 @@ mono_gc_get_vtable_bits (MonoClass *klass)
 	return 0;
 }
 
-void
-mono_gc_register_altstack (gpointer stack, gint32 stack_size, gpointer altstack, gint32 altstack_size)
-{
-}
-
 gboolean
 mono_gc_is_null (void)
 {

src/mono/mono/metadata/sgen-mono.c

@@ -2861,12 +2861,6 @@ mono_gc_invoke_with_gc_lock (MonoGCLockedCallbackFunc func, void *data)
 	return result;
 }
 
-void
-mono_gc_register_altstack (gpointer stack, gint32 stack_size, gpointer altstack, gint32 altstack_size)
-{
-	// FIXME:
-}
-
 guint8*
 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
 {

src/mono/mono/mini/driver.c

@@ -1694,11 +1694,7 @@ mono_get_version_info (void)
 	g_string_append_printf (output, "\tTLS:           \n");
 #endif /* MONO_KEYWORD_THREAD */
 
-#ifdef MONO_ARCH_SIGSEGV_ON_ALTSTACK
-	g_string_append_printf (output, "\tSIGSEGV:       altstack\n");
-#else
 	g_string_append_printf (output, "\tSIGSEGV:       normal\n");
-#endif
 
 	g_string_append_printf (output, "\tArchitecture:  %s\n", MONO_ARCHITECTURE);
 	g_string_append_printf (output, "\tDisabled:      %s\n", DISABLED_FEATURES);

src/mono/mono/mini/exceptions-amd64.c

@@ -829,110 +829,6 @@ mono_arch_ip_from_context (void *sigctx)
 #endif
 }
 
-static MonoObject*
-restore_soft_guard_pages (void)
-{
-	MonoJitTlsData *jit_tls = mono_tls_get_jit_tls ();
-	if (jit_tls->stack_ovf_guard_base)
-		mono_mprotect (jit_tls->stack_ovf_guard_base, jit_tls->stack_ovf_guard_size, MONO_MMAP_NONE);
-
-	if (jit_tls->stack_ovf_pending) {
-		jit_tls->stack_ovf_pending = 0;
-		return (MonoObject *)mini_get_stack_overflow_ex ();
-	}
-
-	return NULL;
-}
-
-/*
- * this function modifies mctx so that when it is restored, it
- * won't execcute starting at mctx.eip, but in a function that
- * will restore the protection on the soft-guard pages and return back to
- * continue at mctx.eip.
- */
-static void
-prepare_for_guard_pages (MonoContext *mctx)
-{
-	gpointer *sp;
-	sp = (gpointer *)(mctx->gregs [AMD64_RSP]);
-	sp -= 1;
-	/* the return addr */
-	sp [0] = (gpointer)(mctx->gregs [AMD64_RIP]);
-	mctx->gregs [AMD64_RIP] = (guint64)restore_soft_guard_pages;
-	mctx->gregs [AMD64_RSP] = (guint64)sp;
-}
-
-static void
-altstack_handle_and_restore (MonoContext *ctx, MonoObject *obj, guint32 flags)
-{
-	MonoContext mctx;
-	MonoJitInfo *ji = mini_jit_info_table_find (MONO_CONTEXT_GET_IP (ctx));
-	gboolean stack_ovf = (flags & 1) != 0;
-	gboolean nullref = (flags & 2) != 0;
-
-	if (!ji || (!stack_ovf && !nullref)) {
-		mono_handle_native_crash (mono_get_signame (SIGSEGV), ctx, NULL);
-		// if couldn't dump or if mono_handle_native_crash returns, abort
-		abort ();
-	}
-
-	mctx = *ctx;
-
-	mono_handle_exception (&mctx, obj);
-	if (stack_ovf) {
-		MonoJitTlsData *jit_tls = mono_tls_get_jit_tls ();
-		jit_tls->stack_ovf_pending = 1;
-		prepare_for_guard_pages (&mctx);
-	}
-	mono_restore_context (&mctx);
-}
-
-void
-mono_arch_handle_altstack_exception (void *sigctx, MONO_SIG_HANDLER_INFO_TYPE *siginfo, gpointer fault_addr, gboolean stack_ovf)
-{
-#if defined(MONO_ARCH_USE_SIGACTION)
-	MonoException *exc = NULL;
-	gpointer *sp;
-	MonoJitTlsData *jit_tls = NULL;
-	MonoContext *copied_ctx = NULL;
-	gboolean nullref = TRUE;
-
-	jit_tls = mono_tls_get_jit_tls ();
-	g_assert (jit_tls);
-
-	/* use TLS as temporary storage as we want to avoid
-	 * (1) stack allocation on the application stack
-	 * (2) calling malloc, because it is not async-safe
-	 * (3) using a global storage, because this function is not reentrant
-	 *
-	 * tls->orig_ex_ctx is used by the stack walker, which shouldn't be running at this point.
-	 */
-	copied_ctx = &jit_tls->orig_ex_ctx;
-
-	if (!mono_is_addr_implicit_null_check (fault_addr))
-		nullref = FALSE;
-
-	if (stack_ovf)
-		exc = mini_get_stack_overflow_ex ();
-
-	/* setup the call frame on the application stack so that control is
-	 * returned there and exception handling can continue. we want the call
-	 * frame to be minimal as possible, for example no argument passing that
-	 * requires allocation on the stack, as this wouldn't be encoded in unwind
-	 * information for the caller frame.
-	 */
-	sp = (gpointer *) ALIGN_DOWN_TO (UCONTEXT_REG_RSP (sigctx), 16);
-	sp [-1] = (gpointer)UCONTEXT_REG_RIP (sigctx);
-	mono_sigctx_to_monoctx (sigctx, copied_ctx);
-	/* at the return from the signal handler execution starts in altstack_handle_and_restore() */
-	UCONTEXT_REG_RIP (sigctx) = (unsigned long)altstack_handle_and_restore;
-	UCONTEXT_REG_RSP (sigctx) = (unsigned long)(sp - 1);
-	UCONTEXT_REG_RDI (sigctx) = (unsigned long)(copied_ctx);
-	UCONTEXT_REG_RSI (sigctx) = (guint64)exc;
-	UCONTEXT_REG_RDX (sigctx) = (stack_ovf ? 1 : 0) | (nullref ? 2 : 0);
-#endif
-}
-
 #ifndef DISABLE_JIT
 GSList*
 mono_amd64_get_exception_trampolines (gboolean aot)

src/mono/mono/mini/exceptions-ppc.c

@@ -641,81 +641,6 @@ mono_arch_ip_from_context (void *sigctx)
 #endif
 }
 
-static void
-altstack_handle_and_restore (MonoContext *mctx, gpointer obj)
-{
-	mono_handle_exception (mctx, obj);
-	mono_restore_context (mctx);
-}
-
-void
-mono_arch_handle_altstack_exception (void *sigctx, MONO_SIG_HANDLER_INFO_TYPE *siginfo, gpointer fault_addr, gboolean stack_ovf)
-{
-#ifdef MONO_CROSS_COMPILE
-	g_assert_not_reached ();
-#else
-#ifdef MONO_ARCH_USE_SIGACTION
-	os_ucontext *uc = (os_ucontext*)sigctx;
-	MonoContext *uc_copy;
-	MonoJitInfo *ji = mini_jit_info_table_find (mono_arch_ip_from_context (sigctx));
-	gpointer *sp;
-	int frame_size;
-
-	if (stack_ovf) {
-		const char *method;
-		/* we don't do much now, but we can warn the user with a useful message */
-		fprintf (stderr, "Stack overflow: IP: %p, SP: %p\n", mono_arch_ip_from_context (sigctx), (gpointer)UCONTEXT_REG_Rn(uc, 1));
-		if (ji && !ji->is_trampoline && jinfo_get_method (ji))
-			method = mono_method_full_name (jinfo_get_method (ji), TRUE);
-		else
-			method = "Unmanaged";
-		fprintf (stderr, "At %s\n", method);
-		abort ();
-	}
-	if (!ji)
-		mono_handle_native_crash (mono_get_signame (SIGSEGV), (MonoContext*)sigctx, siginfo);
-	/* setup a call frame on the real stack so that control is returned there
-	 * and exception handling can continue.
-	 * The frame looks like:
-	 *   ucontext struct
-	 *   ...
-	 * 224 is the size of the red zone
-	 */
-	frame_size = sizeof (MonoContext) + sizeof (gpointer) * 16 + 224;
-	frame_size += 15;
-	frame_size &= ~15;
-	sp = (void**)(UCONTEXT_REG_Rn(uc, 1) & ~15);
-	sp = (void**)((char*)sp - frame_size);
-	/* may need to adjust pointers in the new struct copy, depending on the OS */
-	uc_copy = (MonoContext*)(sp + 16);
-	mono_sigctx_to_monoctx (uc, uc_copy);
-	g_assert (mono_arch_ip_from_context (uc) == MONO_CONTEXT_GET_IP (uc_copy));
-	/* at the return form the signal handler execution starts in altstack_handle_and_restore() */
-	UCONTEXT_REG_LNK(uc) = UCONTEXT_REG_NIP(uc);
-#ifdef PPC_USES_FUNCTION_DESCRIPTOR
-	{
-		MonoPPCFunctionDescriptor *handler_ftnptr = (MonoPPCFunctionDescriptor*)altstack_handle_and_restore;
-
-		UCONTEXT_REG_NIP(uc) = (gulong)handler_ftnptr->code;
-		UCONTEXT_REG_Rn(uc, 2) = (gulong)handler_ftnptr->toc;
-	}
-#else
-	UCONTEXT_REG_NIP(uc) = (unsigned long)altstack_handle_and_restore;
-#if _CALL_ELF == 2
-	/* ELF v2 ABI calling convention requires to put the target address into
-	* r12 if we use the global entry point of a function. */
-	UCONTEXT_REG_Rn(uc, 12) = (unsigned long) altstack_handle_and_restore;
-#endif
-#endif
-	UCONTEXT_REG_Rn(uc, 1) = (unsigned long)sp;
-	UCONTEXT_REG_Rn(uc, PPC_FIRST_ARG_REG) = (unsigned long)uc_copy;
-	UCONTEXT_REG_Rn(uc, PPC_FIRST_ARG_REG + 1) = 0;
-	UCONTEXT_REG_Rn(uc, PPC_FIRST_ARG_REG + 2) = 0;
-#endif
-
-#endif /* !MONO_CROSS_COMPILE */
-}
-
 /*
  * handle_exception:
  *
@@ -778,7 +703,6 @@ mono_arch_handle_exception (void *ctx, gpointer obj)
 	UCONTEXT_REG_Rn (sigctx, PPC_FIRST_ARG_REG) = (gsize)obj;
 
 	/* Allocate a stack frame below the red zone */
-	/* Similar to mono_arch_handle_altstack_exception () */
 	frame_size = 224;
 	frame_size += 15;
 	frame_size &= ~15;