[RFC PATCH] ptrace: add PTRACE_GET_SYSCALL_INFO request

[Elvira Khabirova]

On Wed, 7 Nov 2018 17:44:44 +0100
Oleg Nesterov <oleg at redhat.com> wrote:

> To me PT_IN_SYSCALL_STOP makes no real sense, but I won't argue.
> 
> At least I'd ask to not abuse task->ptrace. ptrace_report_syscall() can clear
> ->ptrace_message on exit if we really want PTRACE_GET_SYSCALL_INFO to fail after  
> that.

I really would not like to rely on ->ptrace_message remaining empty;
this looks too fragile.