RFR : JDK-8032045 : (m/l) Enable compiler and linker safety switches for debug builds

[David Holmes]

For the Open record, the hotspot fix has an issue because 
FASTDEBUG_CFLAGS is unused on linux/bsd.

David

On 9/05/2014 2:07 PM, David Holmes wrote:
> Hi Mike,
>
> This looks okay to me, but of course the proof is in the building and
> testing.
>
> David
>
> On 4/05/2014 1:24 PM, Mike Duigou wrote:
>> Hello;
>>
>> Finally getting back to this issue I have done some cleanup and
>> adjusted the hotspot gcc.make files to use VARIANT rather than
>> DEBUG_LEVEL.
>>
>> This version also add support for the "-fsanitize=undefined" undefined
>> behaviour warnings feature  when it is available (Clang and GCC 4.9).
>> The code to emit the option has been added for Clang but I haven't yet
>> added test for the option's availability under Clang so currently it
>> will be enabled only for GCC.
>>
>> https://bugs.openjdk.java.net/browse/JDK-8032045
>> http://cr.openjdk.java.net/~mduigou/JDK-8032045/6/webrev/
>>
>> Mike
>>
>> On Mar 11 2014, at 05:47 , Magnus Ihse Bursie
>> <magnus.ihse.bursie at oracle.com> wrote:
>>
>>> On 2014-03-11 00:49, Mike Duigou wrote:
>>>> I have updated the patch to respond to Magnus's feedback and to
>>>> accommodate intervening changes to the configure and hotspot make
>>>> files.
>>>>
>>>> https://bugs.openjdk.java.net/browse/JDK-8032045
>>>> http://cr.openjdk.java.net/~mduigou/JDK-8032045/3/webrev/
>>>>
>>>> This version is, hopefully, almost ready to be pushed.
>>>
>>> I have only glanced at the hotspot build changes and can't really say
>>> anything about them. The hotspot team still owns these; I'm cc:ing
>>> them now.
>>>
>>> The top-level build changes looks fine. Thank you Mike for cleaning
>>> things up!
>>>
>>> /Magnus
>>>
>>>>
>>>> Mike
>>>>
>>>> On Feb 20 2014, at 15:43 , Mike Duigou <mike.duigou at oracle.com> wrote:
>>>>
>>>>> Hello all;
>>>>>
>>>>> This issue is a followon to JDK-8030350
>>>>> (https://bugs.openjdk.java.net/browse/JDK-8030350) which enhanced
>>>>> the compiler warnings used for compiling native code. The proposed
>>>>> changes principally impact the Linux platform.
>>>>>
>>>>> While 8030350 was focused on compiler warnings which did not impact
>>>>> code generation, this changeset will, for some configurations,
>>>>> change the native code generated and likely change performance.
>>>>> These proposed option changes prevent specific types of relocation
>>>>> table, stack and heap memory corruption in native code. Preventing
>>>>> these types of memory corruption may be useful for finding certain
>>>>> kinds of bugs though and do provide some minimal additional
>>>>> protections against malicious attacks. They aren't, by any means, a
>>>>> substitute for following appropriate secure coding guidelines.
>>>>>
>>>>> The rationale behind the implementation is as follows. For release
>>>>> builds during the initial phase of JDK 9 I would like to enable
>>>>> only compile time checks. This ends up being similar to the
>>>>> warnings in JDK-8030350. These options have no runtime impact on
>>>>> footprint or performance and very minimal additional compile time
>>>>> cost while providing value. **Release builds are not expected to
>>>>> see any performance or footprint change as a result of this
>>>>> changeset**
>>>>>
>>>>> For fast debug builds we can enable linker protections (relro) and
>>>>> static compile time bounds checks (FORTIFY_SOURCE=1).
>>>>> FORTIFY_SOURCE=1 might be moved to the production builds as well
>>>>> because it has no runtime cost or executable size cost.
>>>>>
>>>>> For slow debug builds we can enable full linker protection (at a
>>>>> potential cost in startup time), runtime bounds checks and stack
>>>>> protection (FORTIFY_SOURCE=2 -fprotect-stack-all). We will likely
>>>>> enable -fprotect-stack-strong when available in GCC 4.9
>>>>>
>>>>> The basis for enabling the additional protections in debug builds
>>>>> is that it will help us find bugs in our native code and we aren't
>>>>> as concerned in debug builds with footprint and performance. Since
>>>>> many developers already do their personal builds in fastdebug or
>>>>> slowdebug mode for testing this will provide good opportunity to
>>>>> shake out any problems with the options while not impacting release
>>>>> builds. Should we find that any of the options provide significant
>>>>> value for their cost we can move them to fastdebug or release. If
>>>>> any of the options prove too costly they can be demoted or removed
>>>>> entirely.
>>>>>
>>>>> https://bugs.openjdk.java.net/browse/JDK-8032045
>>>>> http://cr.openjdk.java.net/~mduigou/JDK-8032045/2/webrev/
>>>>>
>>>>> Additional to enabling the various compiler options I attempted to
>>>>> rationalize some of the skew between the various
>>>>> hotspot/make/{platform}/makefiles/gcc.make files while avoiding
>>>>> changing existing behaviour. I have also introduced the new -Og
>>>>> "optimize for debugging" option and there are now an explicit
>>>>> C{XX}_O_FLAG_DEBUG definitions to complement the
>>>>> C{XX}_O_FLAG_{DEBUG|NORM|HI|HIGHEST|NONE} optimization options.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Mike
>>>
>>