: PING: RFR: 8234624: jstack mixed mode should refer DWARF
Yasumasa Suenaga
suenaga at oss.nttdata.com
Thu Feb 27 05:13:25 UTC 2020
Hi all,
webrev.03 cannot be applied to current jdk/jdk due to 8239224 and 8239462 changes (they updated copyright year).
So I modified webrev (only copyright year changes) to be able to apply to current jdk/jdk.
Could you review it?
http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.04/
I need one more reviewer to push.
Thanks,
Yasumasa
On 2020/02/17 13:07, Yasumasa Suenaga wrote:
> PING: Could you review it?
>
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8234624
>>> webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.03/
>
> This change has been already reviewed by Serguei.
> I need one more reviewer to push.
>
>
> Thanks,
>
> Yasumasa
>
>
> On 2020/02/03 1:37, Yasumasa Suenaga wrote:
>> PING: Could you reveiw this change?
>>
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8234624
>>> webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.03/
>>
>> I believe this change helps troubleshooter to fight to postmortem analysis.
>>
>>
>> Thanks,
>>
>> Yasumasa
>>
>>
>> On 2020/01/19 3:16, Yasumasa Suenaga wrote:
>>> PING: Could you review it?
>>>
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8234624
>>> webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.03/
>>>
>>> I updated webrev. I discussed with Serguei in off list, and I refactored webrev.02 .
>>> It has passed tests on submit repo (mach5-one-ysuenaga-JDK-8234624-4-20200118-1353-8149549).
>>>
>>>
>>> Thanks,
>>>
>>> Yasumasa
>>>
>>>
>>> On 2019/12/15 10:51, Yasumasa Suenaga wrote:
>>>> Hi Serguei,
>>>>
>>>> Thanks for your comment!
>>>> I refactored LinuxCDebugger and LinuxAMD64CFrame in new webrev.
>>>> Also I fixed to free lib->eh_frame.data in libproc_impl.c as Dmitry said.
>>>>
>>>> http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.02/
>>>>
>>>> This change has been passed all tests on submit repo (mach5-one-ysuenaga-JDK-8234624-3-20191214-1527-7538487).
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Yasumasa
>>>>
>>>>
>>>> On 2019/12/14 10:02, serguei.spitsyn at oracle.com wrote:
>>>>> Hi Yasumasa,
>>>>>
>>>>> This is nice move in general.
>>>>> Thank you for working on this!
>>>>>
>>>>> http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.01/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/linux/LinuxCDebugger.java.frames.html
>>>>>
>>>>> 96 long libptr = dbg.findLibPtrByAddress(pc); 97 if (libptr == 0L) { // Java frame 98 Address rbp = context.getRegisterAsAddress(AMD64ThreadContext.RBP); 99 if (rbp == null) { 100 return null; 101 } 102 return new LinuxAMD64CFrame(dbg, rbp, pc, null); 103 } else { // Native frame 104 DwarfParser dwarf; 105 try { 106 dwarf = new DwarfParser(libptr); 107 } catch (DebuggerException e) { 108 Address rbp = context.getRegisterAsAddress(AMD64ThreadContext.RBP); 109 if (rbp == null) { 110 return null; 111 } 112 return new LinuxAMD64CFrame(dbg, rbp, pc, null); 113 } 114 dwarf.processDwarf(pc); 115 Address cfa = ((dwarf.getCFARegister() == AMD64ThreadContext.RBP) && 116 !dwarf.isBPOffsetAvailable()) 117 ? context.getRegisterAsAddress(AMD64ThreadContext.RBP) 118 : context.getRegisterAsAddress(dwarf.getCFARegister()) 119 .addOffsetTo(dwarf.getCFAOffset()); 120 if (cfa == null) { 121 return null; 122 } 123 return new LinuxAMD64CFrame(dbg, cfa, pc, dwarf); 124 }
>>>>>
>>>>>
>>>>> I'd suggest to simplify the logic by refactoring to something like below:
>>>>>
>>>>> long libptr = dbg.findLibPtrByAddress(pc);
>>>>> Address cfa = context.getRegisterAsAddress(AMD64ThreadContext.RBP); // Java frame
>>>>> DwarfParser dwarf = null;
>>>>>
>>>>> if (libptr != 0L) { // Native frame
>>>>> try {
>>>>> dwarf = new DwarfParser(libptr);
>>>>> dwarf.processDwarf(pc);
>>>>> Address cfa = ((dwarf.getCFARegister() == AMD64ThreadContext.RBP) &&
>>>>> !dwarf.isBPOffsetAvailable())
>>>>> ? context.getRegisterAsAddress(AMD64ThreadContext.RBP)
>>>>> : context.getRegisterAsAddress(dwarf.getCFARegister())
>>>>> .addOffsetTo(dwarf.getCFAOffset());
>>>>>
>>>>> } catch (DebuggerException e) { // bail out to Java frame case
>>>>> }
>>>>> }
>>>>> if (cfa == null) {
>>>>> return null;
>>>>> }
>>>>> return new LinuxAMD64CFrame(dbg, cfa, pc, dwarf);
>>>>>
>>>>> http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.01/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/linux/amd64/LinuxAMD64CFrame.java.frames.html
>>>>>
>>>>> 58 long ofs = useDwarf ? dwarf.getReturnAddressOffsetFromCFA()
>>>>>
>>>>> Better to rename 'ofs' => 'offs'.
>>>>>
>>>>> 77 nextCFA = nextCFA.addOffsetTo(- nextDwarf.getBasePointerOffsetFromCFA());
>>>>>
>>>>> Extra space after '-' sign.
>>>>>
>>>>> 71 private Address getNextCFA(DwarfParser nextDwarf, ThreadContext context) {
>>>>>
>>>>> It feels like the logic has to be somehow refactored/simplified as
>>>>> several typical fragments appears in slightly different contexts.
>>>>> But it is not easy to understand what it is.
>>>>> Could you, please, add some comments to key places explaining this logic.
>>>>> Then I'll check if it is possible to make it a little bit simpler.
>>>>>
>>>>> 109 private CFrame javaSender(ThreadContext context) { 110 Address nextCFA; 111 Address nextPC; 112 113 nextPC = getNextPC(false); 114 if (nextPC == null) { 115 return null; 116 } 117 118 DwarfParser nextDwarf = null; 119 long libptr = dbg.findLibPtrByAddress(nextPC); 120 if (libptr != 0L) { // Native frame 121 try { 122 nextDwarf = new DwarfParser(libptr); 123 } catch (DebuggerException e) { 124 nextCFA = getNextCFA(null, context); 125 return (nextCFA == null) ? null : new LinuxAMD64CFrame(dbg, nextCFA, nextPC, null); 126 } 127 nextDwarf.processDwarf(nextPC); 128 } 129 130 nextCFA = getNextCFA(nextDwarf, context); 131 return (nextCFA == null) ? null 132 : new LinuxAMD64CFrame(dbg, nextCFA, nextPC, nextDwarf); 133 }
>>>>>
>>>>> The above can be simplified if a DebuggerException can not be thrown from processDwarf(nextPC):
>>>>> private CFrame javaSender(ThreadContext context) {
>>>>> Address nextPC = getNextPC(false);
>>>>> if (nextPC == null) {
>>>>> return null;
>>>>> }
>>>>> long libptr = dbg.findLibPtrByAddress(nextPC);
>>>>> DwarfParser nextDwarf = null;
>>>>>
>>>>> if (libptr != 0L) { // Native frame
>>>>> try {
>>>>> nextDwarf = new DwarfParser(libptr);
>>>>> nextDwarf.processDwarf(nextPC);
>>>>> } catch (DebuggerException e) { // Bail out to Java frame
>>>>> }
>>>>> }
>>>>> Address nextCFA = getNextCFA(nextDwarf, context);
>>>>> return (nextCFA == null) ? null : new LinuxAMD64CFrame(dbg, nextCFA, nextPC, nextDwarf);
>>>>> }
>>>>>
>>>>> 135 public CFrame sender(ThreadProxy thread) { 136 ThreadContext context = thread.getContext(); 137 138 if (dwarf == null) { // Java frame 139 return javaSender(context); 140 } 141 142 Address nextPC = getNextPC(true); 143 if (nextPC == null) { 144 return null; 145 } 146 147 Address nextCFA; 148 DwarfParser nextDwarf = dwarf; 149 if (!dwarf.isIn(nextPC)) { 150 long libptr = dbg.findLibPtrByAddress(nextPC); 151 if (libptr == 0L) { 152 // Next frame might be Java frame 153 nextCFA = getNextCFA(null, context); 154 return (nextCFA == null) ? null : new LinuxAMD64CFrame(dbg, nextCFA, nextPC, null); 155 } 156 try { 157 nextDwarf = new DwarfParser(libptr); 158 } catch (DebuggerException e) { 159 nextCFA = getNextCFA(null, context); 160 return (nextCFA == null) ? null : new LinuxAMD64CFrame(dbg, nextCFA, nextPC, null); 161 } 162 } 163 164 nextDwarf.processDwarf(nextPC); 165 nextCFA = getNextCFA(nextDwarf, context); 166 return (nextCFA == null) ? null : new LinuxAMD64CFrame(dbg,
>>>>> nextCFA, nextPC, nextDwarf); 167 }
>>>>>
>>>>> This one can be also simplified a little:
>>>>>
>>>>> public CFrame sender(ThreadProxy thread) {
>>>>> ThreadContext context = thread.getContext();
>>>>>
>>>>> if (dwarf == null) { // Java frame
>>>>> return javaSender(context);
>>>>> }
>>>>> Address nextPC = getNextPC(true);
>>>>> if (nextPC == null) {
>>>>> return null;
>>>>> }
>>>>> DwarfParser nextDwarf = null;
>>>>> if (!dwarf.isIn(nextPC)) {
>>>>> long libptr = dbg.findLibPtrByAddress(nextPC);
>>>>> if (libptr != 0L) {
>>>>> try {
>>>>> nextDwarf = new DwarfParser(libptr);
>>>>> nextDwarf.processDwarf(nextPC);
>>>>> } catch (DebuggerException e) { // Bail out to Java frame
>>>>> }
>>>>> }
>>>>> }
>>>>> Address nextCFA = getNextCFA(nextDwarf, context);
>>>>> return (nextCFA == null) ? null : new LinuxAMD64CFrame(dbg, nextCFA, nextPC, nextDwarf);
>>>>> }
>>>>>
>>>>> Finally, it looks like just one method could replace both
>>>>> sender(ThreadProxy thread) and javaSender(ThreadContext context):
>>>>>
>>>>> private CFrame commonSender(ThreadProxy thread) {
>>>>> ThreadContext context = thread.getContext();
>>>>> Address nextPC = getNextPC(false);
>>>>> if (nextPC == null) {
>>>>> return null;
>>>>> }
>>>>> DwarfParser nextDwarf = null;
>>>>>
>>>>> long libptr = dbg.findLibPtrByAddress(nextPC);
>>>>> if (dwarf == null || !dwarf.isIn(nextPC)) {
>>>>> long libptr = dbg.findLibPtrByAddress(nextPC);
>>>>> if (libptr != 0L) {
>>>>> try {
>>>>> nextDwarf = new DwarfParser(libptr);
>>>>> nextDwarf.processDwarf(nextPC);
>>>>> } catch (DebuggerException e) { // Bail out to Java frame
>>>>> }
>>>>> }
>>>>> }
>>>>> Address nextCFA = getNextCFA(nextDwarf, context);
>>>>> return (nextCFA == null) ? null : new LinuxAMD64CFrame(dbg, nextCFA, nextPC, nextDwarf);
>>>>> }
>>>>>
>>>>> I'm still reviewing the dwarf parser files.
>>>>>
>>>>> Thanks,
>>>>> Serguei
>>>>>
>>>>>
>>>>> On 11/28/19 4:39 AM, Yasumasa Suenaga wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I refactored LinuxAMD64CFrame.java . It works fine in serviceability/sa tests and
>>>>>> all tests on submit repo (mach5-one-ysuenaga-JDK-8234624-2-20191128-0928-7059923).
>>>>>> Could you review new webrev?
>>>>>>
>>>>>> http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.01/
>>>>>>
>>>>>> The diff from previous webrev is here:
>>>>>> http://hg.openjdk.java.net/jdk/submit/rev/4bc47efbc90b
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Yasumasa
>>>>>>
>>>>>>
>>>>>> On 2019/11/25 14:08, Yasumasa Suenaga wrote:
>>>>>>> Hi all,
>>>>>>>
>>>>>>> Please review this change:
>>>>>>>
>>>>>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8234624
>>>>>>> webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8234624/webrev.00/
>>>>>>>
>>>>>>>
>>>>>>> According to 2.7 Stack Unwind Algorithm in System V Application Binary Interface AMD64
>>>>>>> Architecture Processor Supplement [1], we need to use DWARF in .eh_frame or .debug_frame
>>>>>>> for stack unwinding.
>>>>>>>
>>>>>>> As JDK-8022183 said, omit-frame-pointer is enabled by default since GCC 4.6, so system
>>>>>>> library (e.g. libc) might be compiled with this feature.
>>>>>>>
>>>>>>> However `jhsdb jstack --mixed` does not do so, it uses base pointer register (RBP).
>>>>>>> So it might be lack of stack frames.
>>>>>>>
>>>>>>> I guess JDK-8219201 is caused by same issue.
>>>>>>>
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Yasumasa
>>>>>>>
>>>>>>>
>>>>>>> [1] https://software.intel.com/sites/default/files/article/402129/mpx-linux64-abi.pdf
>>>>>
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