RFR(10)(S) 8177055: [TESTBUG] test/runtime/ReservedStack/ReservedStackTest.java sometimes fails on Oracle arm64 port after being enabled for open aarch64 port

[Chris Plummer]

Hello,

Please review the following:

https://bugs.openjdk.java.net/browse/JDK-8177055
http://cr.openjdk.java.net/~cjplummer/8177055/webrev.00/webrev.hotspot

The test was recently enabled for aarch64 platforms since support for 
stack reserved pages was added to the open aarch64 port. However, the 
Oracle port still does not have this feature, causing the test to 
sometimes fail when run on it. Note the test is always run on all 
platforms. However, when run on an unsupported platform, "failures" do 
not result in the test actually failing (although crashes will). This is 
intentional and is how the test is suppose to work.

The fix is to change how the test determines if it is running on a 
supported platform. It used to use a fixed list of supported platforms. 
Now I have it spawn a subprocess with "-XX:StackReservedPages=1" to see 
if it produces the warning message you should see on unsupported platforms:

WARNING: Reserved Stack Area not supported on this platform

If it doesn't appear, then the platform is assumed to support the 
feature. I still use the old list of supported platforms (minus aarch64) 
for sanity checks. Basically all platforms in the old list (except 
aarch64) should never show the above warning, and all platforms not in 
the old list (except aarch64) should always show the above warning.

thanks,

Chris