[PATCH] 8170639: [Linux] jsig is limited to a maximum of 64 signals

[Ao Qi]

Hi David Holmes,

Thanks for your reply. It makes sense. Is it possible to create
another bug ID to fix the problem?

Cheers,
Ao Qi

On Mon, Dec 17, 2018 at 7:30 PM David Holmes <david.holmes at oracle.com> wrote:
>
> Thanks for reminding me about the rest of the discussion. The point of
> the RFE I filed was to examine if we could get a consolidated POSIX
> version using sigset_t. I'd rather see that than a point fix for Linux.
>
> Thanks,
> David
>
> On 17/12/2018 6:50 pm, Ao Qi wrote:
> > Hi David Holmes,
> >
> > I am not sure what is the specific issue of "NSIG not being defined".
> > Do you mean the issue mentioned in "but I found that NSIG was missing
> > from signal.h on some architectures, mips being among them"[1]? If
> > yes, James Cowgill answered this in [2]. I check it on MIPS, NSIG is
> > defined in signal.h and it is 128.
> >
> > Cheers,
> > Ao Qi
> >
> > [1] http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-November/025401.html
> > [2] http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-December/025416.html
> >
> > On Mon, Dec 17, 2018 at 8:02 AM David Holmes <david.holmes at oracle.com> wrote:
> >>
> >> Hi,
> >>
> >> Was the issue of NSIG not being defined resolved?
> >>
> >> Thanks,
> >> David
> >>
> >> On 14/12/2018 10:23 pm, Ao Qi wrote:
> >>> Hi all,
> >>>
> >>> Zero does not build on Linux MIPS (actually all Linux of NSIG > 64)
> >>> since OpenJDK 9, because NISG is 128 on MIPS and can not be encoded in
> >>> uint64_t sigs. James Cowgill from Debian tried to push a patch fixing
> >>> this[1] but it seems he failed. I would like to try again to request
> >>> fixing this in http://hg.openjdk.java.net/jdk/jdk. This was fixed in
> >>> AIX implementation.
> >>>
> >>> After applying this patch, zero can be built on MIPS (Debian testing).
> >>> I've run the jtreg tests [2] on x86 Linux.
> >>>
> >>> [1] http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-November/025399.html
> >>> [2] https://download.java.net/openjdk/testresults/12/docs/howtoruntests.html
> >>>
> >>> Cheers,
> >>> Ao Qi
> >>>
> >>> $ hg export -r 52869
> >>> # HG changeset patch
> >>> # User aoqi
> >>> # Date 1544089853 0
> >>> #      Thu Dec 06 09:50:53 2018 +0000
> >>> # Node ID 3eea22b79dc3a4bf26616bde1acb587e3f56e6fe
> >>> # Parent  b4982a22926b4ddf1a7b1f770e4d42ce8c1dd575
> >>> 8170639: [Linux] jsig is limited to a maximum of 64 signals
> >>>
> >>> diff -r b4982a22926b -r 3eea22b79dc3 src/hotspot/os/linux/os_linux.cpp
> >>> --- a/src/hotspot/os/linux/os_linux.cpp Thu Dec 06 11:54:39 2018 +0530
> >>> +++ b/src/hotspot/os/linux/os_linux.cpp Thu Dec 06 09:50:53 2018 +0000
> >>> @@ -4434,10 +4434,7 @@
> >>>
> >>>    // For signal-chaining
> >>>    struct sigaction sigact[NSIG];
> >>> -uint64_t sigs = 0;
> >>> -#if (64 < NSIG-1)
> >>> -#error "Not all signals can be encoded in sigs. Adapt its type!"
> >>> -#endif
> >>> +sigset_t sigs;
> >>>    bool os::Linux::libjsig_is_loaded = false;
> >>>    typedef struct sigaction *(*get_signal_t)(int);
> >>>    get_signal_t os::Linux::get_signal_action = NULL;
> >>> @@ -4516,7 +4513,7 @@
> >>>    }
> >>>
> >>>    struct sigaction* os::Linux::get_preinstalled_handler(int sig) {
> >>> -  if ((((uint64_t)1 << (sig-1)) & sigs) != 0) {
> >>> +  if (sigismember(&sigs, sig)) {
> >>>        return &sigact[sig];
> >>>      }
> >>>      return NULL;
> >>> @@ -4525,7 +4522,7 @@
> >>>    void os::Linux::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
> >>>      assert(sig > 0 && sig < NSIG, "vm signal out of expected range");
> >>>      sigact[sig] = oldAct;
> >>> -  sigs |= (uint64_t)1 << (sig-1);
> >>> +  sigaddset(&sigs, sig);
> >>>    }
> >>>
> >>>    // for diagnostic
> >>> @@ -4616,6 +4613,7 @@
> >>>          (*begin_signal_setting)();
> >>>        }
> >>>
> >>> +    ::sigemptyset(&sigs);
> >>>        set_signal_handler(SIGSEGV, true);
> >>>        set_signal_handler(SIGPIPE, true);
> >>>        set_signal_handler(SIGBUS, true);
> >>>