RFR: JDK-8260022: [ppc] os::print_function_and_library_name shall resolve function descriptors transparently

[Martin Doerr]

On Wed, 20 Jan 2021 06:39:06 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> When function descriptors are fed to os::print_function_and_library_name() to get debug output, it would be very helpful to transparently handle the case where the address is not a code pointer but a function descriptor.
> 
> Of the official OpenJDK platforms this affects only ppc, but also includes at least ia64 for those who maintain ports to that platform.
> 
> Fixing this will also fix the display of signal handlers on linux ppc which still show up without function names after JDK-8258606.
> 
> Before:
> 695 Signal Handlers:
> 696    SIGSEGV: 0x00000fff8d0f4348 in libjvm.so+34882376, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 697     SIGBUS: 0x00000fff8d0f4348 in libjvm.so+34882376, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 698     SIGFPE: 0x00000fff8d0f4348 in libjvm.so+34882376, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 699    SIGPIPE: 0x00000fff8d0e0158 in libjvm.so+34799960, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 700    SIGXFSZ: 0x00000fff8d0e0158 in libjvm.so+34799960, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 701     SIGILL: 0x00000fff8d0f4348 in libjvm.so+34882376, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 702    SIGUSR2: 0x00000fff8d0e0098 in libjvm.so+34799768, sa_mask[0]=00000000000000000000000000000000, sa_flags=SA_RESTART|SA_SIGINFO
> 703     SIGHUP: 0x00000fff8d0e0080 in libjvm.so+34799744, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 704     SIGINT: 0x00000fff8d0e0080 in libjvm.so+34799744, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 705    SIGTERM: 0x00000fff8d0e0080 in libjvm.so+34799744, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 706    SIGQUIT: 0x00000fff8d0e0080 in libjvm.so+34799744, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 707    SIGTRAP: 0x00000fff8d0f4348 in libjvm.so+34882376, sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 
> Now:
> 693 Signal Handlers:
> 694    SIGSEGV: crash_handler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 695     SIGBUS: crash_handler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 696     SIGFPE: crash_handler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 697    SIGPIPE: javaSignalHandler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 698    SIGXFSZ: javaSignalHandler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 699     SIGILL: crash_handler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 700    SIGUSR2: SR_handler in libjvm.so (FD), sa_mask[0]=00000000000000000000000000000000, sa_flags=SA_RESTART|SA_SIGINFO
> 701     SIGHUP: UserHandler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 702     SIGINT: UserHandler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 703    SIGTERM: UserHandler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 704    SIGQUIT: UserHandler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 705    SIGTRAP: crash_handler in libjvm.so (FD), sa_mask[0]=11100100010111111101111111111110, sa_flags=SA_RESTART|SA_SIGINFO
> 
> The patch also adds a little trailing marker `(FD)` as an indication for the developer that this had been a function descriptor.

Hi Thomas,
thanks for fixing it.
Please check PPC64le which doesn't use FunctionDescriptors. They are only used on Big Endian (linux + AIX).
Little Endian implements ABI v2 (also see usage of ABI_ELFv2 in hotspot code).

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PR: https://git.openjdk.java.net/jdk/pull/2157