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

[David Holmes]

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);
>>>