Demangle symbols in stack traces.

Since the demangle debugger extension now gets loaded when booting
from an image, use it in stack traces. Can't print argument values
like on x86, however, since x86_64 uses registers to pass the first
6 arguments rather than the stack we can't easily get to them.

src/system/kernel/arch/x86/arch_debug.cpp

@@ -321,8 +321,39 @@ print_demangled_call(const char* image, const char* symbol, addr_t args,
 	// arguments. Maybe we need DWARF support in the kernel debugger. For now
 	// just print out the function signature without the argument values.
 
-	// TODO x86_64.
-	return B_NOT_SUPPORTED;
+	static const size_t kBufferSize = 256;
+	char* buffer = (char*)debug_malloc(kBufferSize);
+	if (buffer == NULL)
+		return B_NO_MEMORY;
+
+	bool isObjectMethod;
+	const char* name = debug_demangle_symbol(symbol, buffer, kBufferSize,
+		&isObjectMethod);
+	if (name == NULL) {
+		debug_free(buffer);
+		return B_ERROR;
+	}
+
+	kprintf("<%s> %s(", image, name);
+
+	size_t length;
+	int32 type, i = 0;
+	uint32 cookie = 0;
+	while (debug_get_next_demangled_argument(&cookie, symbol, buffer,
+			kBufferSize, &type, &length) == B_OK) {
+		if (i++ > 0)
+			kprintf(", ");
+
+		if (buffer[0])
+			kprintf("%s", buffer);
+		else
+			kprintf("???");
+	}
+
+	debug_free(buffer);
+
+	kprintf(")");
+	return B_OK;
 }
 
 
@@ -360,10 +391,10 @@ print_stack_frame(Thread* thread, addr_t ip, addr_t bp, addr_t nextBp,
 
 		if (!exactMatch || !demangle || status != B_OK) {
 			if (symbol != NULL) {
-				kprintf("<%s>:%s%s", image, symbol,
+				kprintf("<%s> %s%s", image, symbol,
 					exactMatch ? "" : " (nearest)");
 			} else
-				kprintf("<%s@%p>:unknown", image, (void*)baseAddress);
+				kprintf("<%s@%p> <unknown>", image, (void*)baseAddress);
 		}
 
 		kprintf(" + %#04lx\n", ip - baseAddress);