RFR(M) 8212605: Pure-Java implementation of AccessController.doPrivileged

dean.long at oracle.com dean.long at oracle.com
Wed Oct 31 22:23:12 UTC 2018


This change implements AccessController.doPrivileged in Java.  This 
gives a performance improvement while also being useful to Project Loom 
by removing the Java --> native --> Java transition.  One reason 
doPrivileged has historically been in native is because of the need to 
guarantee the cleanup of the privileged context when doPrivileged 
returns.  To do that in Java, the information that 
AccessController.getContext needs is pushed onto the Java stack as 
arguments to a method that getContext will recognize during its stack 
walk.  This allows us to remove the native privileged stack while 
guaranteeing that the privileged context goes away when the method returns.

Tested with tier1-tier3 hotspot and jdk tests and JCK api/java_security 
tests.  For the first few rounds of testing, I kept the old native 
privileged stack and compared the results of the old and new 
implementations for each getContext call, which did catch some early 
bugs.  The changes were also examined by internal security experts and 
run through additional internal security tests.

The improvement on this [1] doPrivileged microbenchmark is approximate 50x.

There is no attempt to optimize getContext() or security permission 
checks in this change, however, this is intended to be a first step 
towards other possible improvements, for example those proposed here [2].



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