How to prevent another process to debug syscall with ptrace

问题

In ptrace I can debug another process to print all the syscall numver that the remote process call.l , with this steps.

1. Attach to process with PTRACE_ATTACH.
2. waitpid (with `__WALL flags) to be sure the remote process has been stopped.
3. In while (cond) print on register that store the syscall number with PTRACE_PEEKUSER

How the remote process can prevent that ?is there any signal that it can to register and print "stop debug me!!"??

PTRACE_ATTACH send SIGSTOP for remote process,but process can't handle that. And PTRACE_PEEKUSER do not send any signal to remote process.

来源：https://stackoverflow.com/questions/61667231/how-to-prevent-another-process-to-debug-syscall-with-ptrace