Re: [PATCH 1/3] [POC] test implementaion of rt-signals

[Florian Bezdeka <florian.bezdeka@siemens.com>]

On Thu, 2023-09-07 at 10:48 +0000, Johannes Kirchmair wrote:
> Hey Florian,
> 
> > -----Original Message-----
> > From: Florian Bezdeka <florian.bezdeka@siemens.com>
> [...]
> > > +COBALT_SYSCALL32emu(sigaction, current,
> > > +                 (int sig, void __user *handler, void __user *restorer))
> > > +{
> > > +     struct cobalt_ppd *sys_ppd = cobalt_ppd_get(0);
> > > +
> > > +     if (sig < 0 || sig >= _NSIG)
> > > +             return -EINVAL;
> > > +
> > > +     sys_ppd->sighand[sig] = handler;
> > > +
> > > +     if (!sys_ppd->sigrestorer)
> > > +             sys_ppd->sigrestorer = restorer;
> > > +
> > > +     return 0;
> > > +}
> > > +
> > 
> > You did not touch the syscall32-table.h (x86 specific), so I would
> > expect that your compat support is broken right now. You should end up
> > in the "native" so x86_64 implementation. That brings me to the next
> > question:
> Checked this and you are right, we end up in the "native" implementation of the syscall.
> Will drop the compat syscall.

Fine.

> 
> > 
> > Can't we avoid a special compat case here? The pointers themselfs are
> > corrected by the syscall entry machinery but the memory pointed to is
> > not. So is the memory pointed to by handler and restorer different in
> > terms of memory layout/padding?
> We don’t access the memory pointed to from kernel space, so this should not be imported or am I missing something?

This is obsolete. We could drop the compat case.

> 
> > 
> > In addition you should update kernel/cobalt/trace/cobalt-posix.h to get
> > proper trace support.
> Changed the following define to look like this:
> #define __cobalt_syscall_name(__nr)					\
> 	__print_symbolic((__nr),					\
> 		....
> 		__cobalt_symbolic_syscall(pselect64),			\
> 		__cobalt_symbolic_syscall(sigreturn),			\
> 		__cobalt_symbolic_syscall(sigaction))
> 
> Is this sufficient or do I have to change something else?

Yes, that should be sufficient.

> 
> Best regards Johannes
> 
>