On Fri, Nov 30, 2018 at 12:29:21PM +0100, Oleg Nesterov wrote: > On 11/30, Dmitry V. Levin wrote: > > On Thu, Nov 29, 2018 at 03:47:43PM +0100, Oleg Nesterov wrote: > > > > > > so that PTRACE_GETEVENTMSG users can easily tell > > > > whether this new semantics is supported by the kernel or not. > > > > > > Yes. And how much this can help? Again, an application can trivially detect > > > if this feature implemented or not, and it should do this anyway if it wants > > > to (try to) use PTRACE_EVENTMSG_SYSCALL_ENTRY/EXIT ? > > > > How an application can easily detect whether this feature is implemented? > > As I already said, it can just do ptrace(PTRACE_GET_SYSCALL_INFO, NULL) ? > If it returns -EIO then this feature is not implemented. Any other error > code (actually EINVAL or EFAULT) means it is implemented. Fair enough. We can change PTRACE_EVENTMSG_SYSCALL_ENTRY/EXIT to 1/2 if you like, and document this trick somewhere. -- ldv
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