Re: [PATCH RESEND v3 1/3] ptrace: pass type of a syscall-stop in ptrace_message

From: Oleg Nesterov
Date: Mon Nov 26 2018 - 09:56:49 EST


On 11/25, Elvira Khabirova wrote:
>
> + * These values are stored in task->ptrace_message by tracehook_report_syscall_*
> + * to describe current syscall-stop.
> + *
> + * Values for these constants are chosen so that they do not appear
> + * in task->ptrace_message by other means.
> + */
> +#define PTRACE_EVENTMSG_SYSCALL_ENTRY 0x80000000U
> +#define PTRACE_EVENTMSG_SYSCALL_EXIT 0x90000000U

Stupid question, why not

#define PTRACE_EVENT_SYSCALL_ENTRY 8
#define PTRACE_EVENT_SYSCALL_EXIT 9

right after other PTRACE_EVENT_* constants?

The next 3/3 tries to detect PTRACE_EVENT_SECCOMP case anyway, so I am not sure
I understand what "do not appear in task->ptrace_message by other means" actually
means...

Oleg.