Re: [LTP] [PATCH] syscalls: fix some failure on arch X86_64

Subrata Modak
2009-11-16T08:14:11Z

Liubo,

Are you sending an updated patch post this discussion ?

Regards--
Subrata

On Wed, 2009-11-11 at 13:03 +0800, Wei Yongjun wrote:
>
> Mike Frysinger wrote:
> > On Tuesday 10 November 2009 04:38:30 liubo wrote:
> >
> >> 1) rt_sigaction
> >> "sigaction" has the structure:
> >>
> >> struct sigaction {
> >> __sighandler_t sa_handler;
> >> unsigned long sa_flags;
> >> #ifdef SA_RESTORER
> >> __sigrestore_t sa_restorer;
> >> #endif
> >> sigset_t sa_mask; /* mask last for extensibility */
> >> };
> >>
> >> However, on arch x86_64, if we directly get to call rt_sigaction,
> >> the argument "sa_restorer" will not be fulfilled, and this will lead
> >> to segment fault.
> >> on arch x86_64, if sa_restorer is not set, kernel will lead to segment
> >> fault. In other arch, if sa_restorer is not set, kernel can do the correct
> >> work. To avoid this segment fault, we use glibc function
> >> "int sigaction(...);" instead, which can fulfill the argument
> >> "sa_restorer".
> >>
> >
> > which defeats the purpose of the test. there is no guarantee that the C
> > library sigaction function is implemented via the __NR_rt_sigaction syscall.
> >
>
> In x86_64, it do this. And If we want to use __NR_rt_sigaction syscall
> directly, we must fill the sa_restorer and set the RESTORER flag to
> sa_mask. If we do not set the sa_restorer, kill will always cause
> segment fault.
>
> >
> >> 2) rt_sigprocmask
> >> This failure contains two aspects,
> >> the first is the segment fault as described in 1),
> >> the second is that testcase uses a unknown signal 33 for test,
> >> and this will lead sigaction cannot bind signal 33 to the action.
> >>
> >> So, we attempt to use a known signal instead, such as 34.
> >>
> >
> > which is just as bogus and unportable. if the test needs a real time signal,
> > it should leverage the sigrtmin...sigrtmax defines.
> > -mike
> >
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