Re: status of Linux ptrace on amd64?

[Alexander Nasonov <alnsn%yandex.ru@localhost>]

Christos Zoulas wrote:
> In article <20141202221949.GA4053@neva>,
> Alexander Nasonov  <alnsn%yandex.ru@localhost> wrote:
> >I don't think source code is available.
> 
> It is going to be hard to get it to work....

Yeah. I can't make any further progress. Working gdb on 32bit Linux
binary gave me a false hope.

I'm stuck at orig_ax. If I understand correctly, pin (and strace
too) want to know a syscall number of a process stopped in a syscall
and they query for orig_ax. I use (lt->l_sysent - emul_linux.e_sysent)
to get a syscall number but l_sysent is always NULL. I haven't
looked at whether a traced process is really in syscall and whether
l_sysent is guaranteed to be syncronised accross cpus (I think, it's
not but l_sysent is always NULL in nonsmp kernel too).

Anyway, I've got some working code. It's not ptrace related, though.
To make the tool run, I needed to add support for /proc/sys/kernel/osrelease.
The patch is here

http://www.netbsd.org/~alnsn/procfs-sys-kernel-osrelease.diff

Alex