Added syscall _kern_kernel_debugger() to enter the kernel debugger.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@31965 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/debug.h

@@ -161,6 +161,7 @@ extern status_t	debug_get_next_demangled_argument(uint32* _cookie,
 extern struct thread* debug_set_debugged_thread(struct thread* thread);
 extern struct thread* debug_get_debugged_thread();
 
+extern status_t	_user_kernel_debugger(const char *message);
 extern void		_user_debug_output(const char *userString);
 
 #ifdef __cplusplus

headers/private/system/syscalls.h

@@ -420,6 +420,7 @@ extern status_t		_kern_get_port_message_info_etc(port_id port,
 						bigtime_t timeout);
 
 // debug support functions
+extern status_t		_kern_kernel_debugger(const char *message);
 extern void			_kern_debugger(const char *message);
 extern int			_kern_disable_debugger(int state);
 

src/system/kernel/debug/debug.cpp

@@ -1660,6 +1660,27 @@ debug_get_debugged_thread()
 //	userland syscalls
 
 
+status_t
+_user_kernel_debugger(const char *userMessage)
+{
+	if (geteuid() != 0)
+		return B_NOT_ALLOWED;
+
+	char message[512];
+	strcpy(message, "USER: ");
+	size_t len = strlen(message);
+
+	if (userMessage == NULL || !IS_USER_ADDRESS(userMessage)
+		|| 	user_strlcpy(message + len, userMessage, sizeof(message) - len)
+			< 0) {
+		return B_BAD_ADDRESS;
+	}
+
+	kernel_debugger(message);
+	return B_OK;
+}
+
+
 void
 _user_debug_output(const char* userString)
 {