RFR: 8221639: [x32] expand_exec_shield_cs_limit workaround is undefined code after JDK-8199717

[David Holmes]

Hi Severin,

I'll have to delve into this more deeply (but I'm on Easter break for 
the next 4 days). I don't recall ever being aware of 
"suppress_primordial_thread_resolution"!

David

On 18/04/2019 11:41 pm, Severin Gehwolf wrote:
> Hi,
> 
> Could I please get reviews for this Linux x32 fix? JDK-8199717 added a
> performance optimization to only capture the initial stack size when
> launched via non-java launchers. However, on Linux x32, there is old
> code being executed to work around the exec shield CS limit. That code
> depends on the initial stack size being captured. Right now this is
> undefined code: Pointer artithmetic on NULL pointer.
> 
> src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp:884:73: runtime error: pointer index expression with base 0x00000000 overflowed to 0xffffb000
> 
> I propose to not perform the optimization of JDK-8199717 for Linux x32.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8221639
> webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8221639/01/webrev/
> 
> Testing: release/fastdebug builds on x32 Linux, inspecting
> -Xlog:os=info messages, currently running through jdkd/submit. Tier 1
> tests on Linux x86_64
> 
> Thoughts?
> 
> Thanks,
> Severin
>