RFR: JDK-8258606: os::print_signal_handlers() should resolve the function name of the handlers

[David Holmes]

On 24/12/2020 4:31 pm, Thomas Stuefe wrote:
> On Mon, 21 Dec 2020 09:07:07 GMT, David Holmes <dholmes at openjdk.org> wrote:
> 
>>> This patch changes the printout for our signal handlers in hs-err files and in `jcmd VM.info` to show the function names of the handlers. This is also interesting for CheckJNI.
>>>
>>> Before:
>>> Signal Handlers:
>>> SIGSEGV: [libjvm.so+0xbb8ff0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGBUS: [libjvm.so+0xbb8ff0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGFPE: [libjvm.so+0xbb8ff0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGPIPE: [libjvm.so+0xbb8ff0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGXFSZ: [libjvm.so+0xbb8ff0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGILL: [libjvm.so+0xbb8ff0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGUSR2: [libjvm.so+0xbb8e90], sa_mask[0]=00000000000000000000000000000000, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGHUP: [libjvm.so+0xbb95b0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGINT: [libjvm.so+0xbb95b0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGTERM: [libjvm.so+0xbb95b0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>> SIGQUIT: [libjvm.so+0xbb95b0], sa_mask[0]=11111111011111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>
>>> Now:
>>> Signal Handlers:
>>>     SIGSEGV: [javaSignalHandler(int, siginfo_t*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>      SIGBUS: [javaSignalHandler(int, siginfo_t*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>      SIGFPE: [javaSignalHandler(int, siginfo_t*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>     SIGPIPE: [javaSignalHandler(int, siginfo_t*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>     SIGXFSZ: [javaSignalHandler(int, siginfo_t*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>      SIGILL: [javaSignalHandler(int, siginfo_t*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>     SIGUSR2: [SR_handler(int, siginfo_t*, ucontext*)+0 in libjvm.so], sa_mask[0]=00000000000000000000000000000000, sa_flags=SA_RESTART|SA_SIGINFO
>>>      SIGHUP: [UserHandler(int, void*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>      SIGINT: [UserHandler(int, void*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>     SIGTERM: [UserHandler(int, void*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>     SIGQUIT: [UserHandler(int, void*, void*)+0 in libjvm.so], sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
>>>     SIGTRAP: SIG_DFL, sa_mask[0]=00000000000000000000000000000000, sa_flags=none
>>>
>>> The patch introduces a new function, `os::print_function_and_library_name`, which prints a combined function and library name.
>>>
>>> It also introduces gtests for that function.
>>>
>>> I plan to use it in other places to, and unify similar coding, e.g. when printing stack traces (NMT, VMError) or pointer locations (os::print_location). But I leave that for a future RFE.
>>
>> src/hotspot/os/posix/signals_posix.cpp line 1352:
>>
>>> 1350:   LINUX_ONLY(sa.sa_flags &= SA_RESTORER_FLAG_MASK;)
>>> 1351:
>>> 1352:   st->print("%10s: ", os::exception_name(sig, buf, buflen));
>>
>> Where does the 10 come from? Why do we need to limit it?
> 
>> A minor comment, but otherwise this seems quite reasonable.
>>
>> Thanks,
>> David
> 
> Thanks, David!
> 
> `%10s` is not a limit, its for alignment. It makes all the signal names nicely aligned (all colons end up in the same column).

Ah! :) Thanks.

David

> ..Thomas
> 
> -------------
> 
> PR: https://git.openjdk.java.net/jdk/pull/1839
>