RFR(M): 8139864: Improve handling of stack protection zones.

[Lindenmaier, Goetz]

Hi,

I ran the change through our night builds - all jtreg tests are clean.
(and the other tests as well.)
I prepared a complete and - from my side - final webrev:
http://cr.openjdk.java.net/~goetz/webrevs/8139864-StackZones/webrev.01/
This includes the fixes proposed by David as well as some minor fixes to 
get it compiling on windows. 

So to capture the change still the split webrevs might be a good starting point:
http://cr.openjdk.java.net/~goetz/webrevs/8139864-StackZones/webrev.00-basic/
http://cr.openjdk.java.net/~goetz/webrevs/8139864-StackZones/webrev.00-spread/

David, can I consider this reviewed?
I please need a second reviewer and a sponsor.

Best regards,
  Goetz.


> -----Original Message-----
> From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-
> bounces at openjdk.java.net] On Behalf Of Lindenmaier, Goetz
> Sent: Freitag, 27. November 2015 10:28
> To: David Holmes <david.holmes at oracle.com>; Coleen Phillimore
> (coleen.phillimore at oracle.com) <coleen.phillimore at oracle.com>; hotspot-
> runtime-dev at openjdk.java.net
> Subject: RE: RFR(M): 8139864: Improve handling of stack protection zones.
> 
> Hi David,
> 
> thanks for looking at this change!
> I edited the thinks you remarked, thanks for spotting that.
> 
> I'll run the change through our testing to assure I catch all
> issues with jtreg.  We have some systems with other page sizes.
> 
> Best regards,
>   Goetz.
> 
> > -----Original Message-----
> > From: David Holmes [mailto:david.holmes at oracle.com]
> > Sent: Freitag, 27. November 2015 06:33
> > To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; Coleen Phillimore
> > (coleen.phillimore at oracle.com) <coleen.phillimore at oracle.com>;
> hotspot-
> > runtime-dev at openjdk.java.net
> > Subject: Re: RFR(M): 8139864: Improve handling of stack protection zones.
> >
> > Hi Goetz,
> >
> > On 26/11/2015 1:55 AM, Lindenmaier, Goetz wrote:
> > > Hi,
> > >
> > > For a description of the problem see
> > https://bugs.openjdk.java.net/browse/JDK-8139864
> > >
> > > This is a first version of my implementation of the proposal '3' that was
> > discussed here:
> > > http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2015-
> > October/016085.html
> > > which is continued here
> > > http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2015-
> > November/016805.html
> > >
> > > Opposed to my original proposal, I did not introduce new flags. I
> > documented the
> > > old flags to specify 4K pages, and save the ergonomic values in static
> fields
> > of JavaThread.
> > > This avoids two sets of similar flags.
> >
> > That seems like a good compromise. Though not sure about placement in
> > JavaThread when everything else stack-related seems to be in os class.
> >
> > > To simplify reviewing, I made two webrevs for the first round:
> > > The basic changes to determining the sizes of the zones to protect are in
> > this partial webrev:
> > > http://cr.openjdk.java.net/~goetz/webrevs/8139864-
> > StackZones/webrev.00-basic/
> > > This contains the functional change.
> >
> > This seems okay to me - though I don't claim expertise in this area.
> >
> > A couple of minor nits:
> >
> > src/share/vm/runtime/thread.hpp
> >
> > 1364   static size_t stack_yellow_zone_size() {
> > 1365     assert(_stack_red_zone_size > 0, "Don't call this before the
> > field is initialized.");
> >
> > The assert should check yellow size
> >
> > 1383   static size_t stack_shadow_zone_size() {
> > 1384     assert(_stack_red_zone_size > 0, "Don't call this before the
> > field is initialized.");
> >
> > The assert should check shadow size.
> >
> > ---
> >
> > src/share/vm/runtime/globals.hpp
> >
> > kB -> KB
> >
> > > I also fixed the bounds of ThreadStackSize and CompilerThreadStackSize
> > which
> > > allowed to specify stacks >> max_intx.
> >
> > Ok - not sure how this was missed given we do the same for
> > VMThreadStackSize :)
> >
> >
> > > If we agree on this, I need to replace all occurrences of the three flags by
> > accessor calls.
> > > This allows to simplify all the platform code which computed the space
> > required
> > > over and over again:
> > > http://cr.openjdk.java.net/~goetz/webrevs/8139864-
> > StackZones/webrev.00-spread/
> >
> > That all seems okay to me.
> >
> > > Actually I think there is no need that the shadow zone is page aligned.
> > There are no
> > > pages to allocate or protect.  The size of this zone is only used for
> banging.
> > In most
> > > places only the upper bound of the zone is banged.  In few places, all
> pages
> > within
> > > this zone are banged.  But this code also does not depend on a page
> > aligned size.
> > > Removing the rounding to page sizes here could free up stack space for
> real
> > usage.
> > > But I think that should be done in an extra change.
> > >
> > > I also fixed the bounds of ThreadStackSize and CompilerThreadStackSize
> > which
> > > allowed to specify stacks >> max_intx.
> > >
> > > If this is agreed on, I will check for jtreg tests that fail on systems with
> stack
> > > pages > 4K and add the fixes to this change.
> >
> > You may also need to check the tests for valid command-line args given
> > the range adjustments on the stack sizes.
> >
> > Thanks,
> > David
> > -----
> >
> > > Best regards,
> > >    Goetz.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >