(9) RFR: 8064815 Zero+PPC64: Stack overflow when running Maven

[Severin Gehwolf]

Hi,

Could I please get a review and sponsor for the following fix:

bug: https://bugs.openjdk.java.net/browse/JDK-8064815
webrev:
https://jerboaa.fedorapeople.org/bugs/openjdk/JDK-8064815/webrev.0/

When running Maven ("mvn") on a Zero variant build on PPC/PPC64 hardware
it throws a StackOverflowError. This is because the stack bound
calculation does not account for red and yellow pages.

The bug has a slightly different patch attached. The changes to
hotspot/src/os/linux/vm/os_linux.cpp aren't needed for this bug.

Testing done: A Zero variant build of OpenJDK 9 on PPC/PPC64 throws
StackOverflowError without this fix and works fine with this fix
applied.

Note that this problem seems to surface on architectures where pages are
large. PPC is one such instance. Page size there is 64KB and Zero
initially sets its minimal stack allowance to 64KB (one page),
src/os_cpu/linux_zero/vm/os_linux_zero.cpp. In os::init_2 this gets
potentially increased if min_stack_allowed is small. The case on PPC
Zero.

However, then later at runtime the calculation of available stack is
wrong since it does not account for red and yellow pages. Thus it thinks
there is too little stack available where in fact more stack is
available.

Thanks,
Severin