Re: PATCH: Add ia32 support to x32 strace

[Dmitry V. L. <ld...@al...>]

On Tue, Apr 17, 2012 at 05:03:20PM -0700, H.J. Lu wrote:
> On Tue, Apr 17, 2012 at 4:58 PM, Dmitry V. Levin <ld...@al...> wrote:
> > On Tue, Apr 17, 2012 at 11:05:04AM -0700, H.J. Lu wrote:
> >> Hi,
> >>
> >> This patch adds ia32 support to x32 strace.  Tested on Linux/x32.
> > [...]
> >> @@ -868,15 +874,14 @@ get_scno(struct tcb *tcp)
> >>       }
> >>  # endif
> >>  # ifdef X32
> >> -     if (currpers == 0 || currpers == 1) {
> >> -             fprintf(stderr, "syscall_%lu (...) in unsupported %s "
> >> -                     "mode of process PID=%d\n", scno,
> >> -                     currpers == 0 ? "64-bit" : "32-bit", tcp->pid);
> >> +     if (currpers == 0) {
> >> +             fprintf(stderr, "syscall_%lu (...) in unsupported 64-bit "
> >> +                     "mode of process PID=%d\n", scno, tcp->pid);
> >>               return 0;
> >>       }
> >> -# else
> >> -     update_personality(tcp, currpers);
> >> +     else if (currpers == 1)
> >>  # endif
> >> +     update_personality(tcp, currpers);
> >>  #elif defined(IA64)
> >>  #    define IA64_PSR_IS      ((long)1 << 34)
> >>       if (upeek(tcp, PT_CR_IPSR, &psr) >= 0)
> >
> > This part of the change seems to be wrong: if strace supports two personalities
> > on X32, it should be able to switch to any of them, not just to
> > currpers == 1.  Looks like additional currpers translation is needed for
> > the X32 case.
> 
> currpers is set the same value for both x32 and x86-64 strace,
> 
> 0: x86-64
> 1: ia32
> 2. x32
> 
> For x32 strace, when currpers == 1, we call update_personality to update
> personality.  When currpers == 2, we do nothing since the current
> personality is x32.

We have to handle the case when currpers == 2 and current_personality == 1.
Supposing that currpers == 2 on X32 translates to current_personality == 0,
we have to call update_personality(tcp, 0) in that case.


-- 
ldv