Re: [Qemu-devel] [PATCH 33/34] linux-user: Support for restarting system calls for CRIS targets

[Edgar E. Iglesias]

On Thu, Sep 10, 2015 at 08:12:21PM +0100, Peter Maydell wrote:
> On 6 September 2015 at 00:57, Timothy E Baldwin
> <address@hidden> wrote:
> > Signed-off-by: Timothy Edward Baldwin <address@hidden>
> > ---
> >
> > WARNING - NOT TESTED
> >
> >  linux-user/cris/syscall.h | 2 ++
> >  linux-user/main.c         | 6 +++++-
> >  linux-user/signal.c       | 2 +-
> >  3 files changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/linux-user/cris/syscall.h b/linux-user/cris/syscall.h
> > index 2957b0d..29218e2 100644
> > --- a/linux-user/cris/syscall.h
> > +++ b/linux-user/cris/syscall.h
> > @@ -44,3 +44,5 @@ struct target_pt_regs {
> >  #define TARGET_MLOCKALL_MCL_FUTURE  2
> >
> >  #endif
> > +
> > +#define TARGET_USE_ERESTARTSYS 1
> > diff --git a/linux-user/main.c b/linux-user/main.c
> > index a59907e..a9eb15c 100644
> > --- a/linux-user/main.c
> > +++ b/linux-user/main.c
> > @@ -2878,7 +2878,11 @@ void cpu_loop(CPUCRISState *env)
> >                               env->pregs[7],
> >                               env->pregs[11],
> >                               0, 0);
> > -            env->regs[10] = ret;
> > +            if (ret == -TARGET_ERESTARTSYS) {
> > +                env->pc -= 2;
> > +            } else if (ret != -TARGET_QEMU_ESIGRETURN) {
> > +                env->regs[10] = ret;
> > +            }
> >              break;
> >          case EXCP_DEBUG:
> >              {
> > diff --git a/linux-user/signal.c b/linux-user/signal.c
> > index e17514e..3741517 100644
> > --- a/linux-user/signal.c
> > +++ b/linux-user/signal.c
> > @@ -3761,7 +3761,7 @@ long do_sigreturn(CPUCRISState *env)
> >
> >      restore_sigcontext(&frame->sc, env);
> >      unlock_user_struct(frame, frame_addr, 0);
> > -    return env->regs[10];
> > +    return -TARGET_QEMU_ESIGRETURN;
> >  badframe:
> >      force_sig(TARGET_SIGSEGV);
> >  }
> 
> Looks OK, but this one I'm not sure enough about the CRIS instruction
> set and the surrounding code doesn't clarify. Edgar -- is the CRIS
> instruction for "take linux system call" always exactly 2 bytes long?
>

Yes, those are always 2 bytes.

Cheers,
Edgar