RFR(XS): 8193308: Disallow installing user signal handlers for SIGBUS on OSX

[mandy chung]

(fixed formatting)

As documented in [1], SIGBUS is listed as the signals used by the 
HotSpot implementation. It could be just that it was missed from day 1.

Have you checked the native signal chaining support via libjsig.so? It 
should disallow to install a user native signal handler for SIGBUS.

I think JVM_RegisterSignal should disallow installing a user handler for 
one of the implementation-specific signals for all platforms. That'll 
simplify your fix.  I would think the compatibility risk should be low 
as rare cases would want to intercept SIGBUS which is also clearly 
documented in [1].

Mandy
[1] 
https://docs.oracle.com/javase/9/troubleshoot/handle-signals-and-exceptions.htm#JSTGD356


On 7/02/2018 1:19 AM, Robin Westberg wrote:
 > Hi all,
 >
 > Please review the following change to disallow installing user
 > signal handlers for SIGBUS on OSX. On OSX, SIGBUS is used
 > internally by the VM (where most other platforms only use SIGSEGV),
 > and installing a user handler can lead to a deadlock.
 >
 > Issue: https://bugs.openjdk.java.net/browse/JDK-8193308
 > Webrev: http://cr.openjdk.java.net/~rwestberg/8193308/webrev.00/
 >
 > Best regards,
 > Robin