Hi, Latest webrev with JNI properly compiled with -fomit-frame-pointer and -O3. There was a bug in the test where the exception wasn't properly rethrown: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8208091/webrev.03/
I'm going to run this through jdk-submit too. Adding build-dev for build changes. Thanks, Severin On Fri, 2018-08-03 at 18:45 +0200, Severin Gehwolf wrote: > Hi all, > > On Mon, 2018-07-30 at 21:23 -0700, Sharath Ballal wrote: > > > Ok. It looks like we don't even have a "jstack --mixed" test. Could > > > you add one? It would be even better if the test included a JNI lib > > > that wasn't compiled with -fno-omit-frame-pointer so you don't need > > > to rely on glibc to reproduce this issue (or is glibc pretty much > > > always compiled without -fno-omit-frame-pointer)? Or if Sharath > > > agrees, file a bug to have a test added. > > > > That’s a good suggestion. Severin you can either write a test or > > open a bug for it. > > Latest webrev with a test: > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8208091/webrev.02/ > > The test fails prior the test on affected systems and passes after. > There are still issues with getting the test's JNI properly compiled > the way it's supposed to. I've asked for help on build-dev[1]. Example > runs: > > Before patch: > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8208091/before_patch.txt > > After patch: > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8208091/after_patch.txt > > Thanks, > Severin > > [1] http://mail.openjdk.java.net/pipermail/build-dev/2018-August/022819.html > > > -----Original Message----- > > From: Chris Plummer > > Sent: Monday, July 30, 2018 10:03 PM > > To: Severin Gehwolf; Sharath Ballal; serviceability-dev > > Subject: Re: [PING] RFR(XS): 8208091: SA: jhsdb jstack --mixed throws > > UnmappedAddressException on i686 > > > > Hi Severin, > > > > On 7/30/18 1:28 AM, Severin Gehwolf wrote: > > > Hi Chris, > > > > > > On Thu, 2018-07-26 at 14:07 -0700, Chris Plummer wrote: > > > > I had looked at this review when it came out, but was hesitant to > > > > ok > > > > it because I really don't know this code at all. If you can get > > > > another reviewer who does know the code, then I'll approve it. > > > > > > Sharath Ballal reviewed it, but he's not a Reviewer as per the > > > OpenJDK > > > census. As to whether he knows the code, I don't know. He's on CC. > > > > Yes, but I was asking for a second reviewer (not counting me). > > > > > > > This only impacts 32-bit, right? If so, keep in mind that it > > > > won't > > > > get tested by Oracle testing, including the submit repo, so make > > > > sure you do thorough testing. > > > > > > It only impacts 32-bit, yes. I understand that Oracle isn't > > > testing > > > 32- bit x86 any more. The change itself should be fairly low risk > > > since it's changing only a 32-bit-x86-linux-only file and the > > > native > > > bits don't seem to match what the Java code does[1]. > > > REG_INDEX(reg) > > > being defined as: > > > > > > #define REG_INDEX(reg) > > > sun_jvm_hotspot_debugger_x86_X86ThreadContext_##reg > > > > > > and being used as: > > > > > > REG_INDEX(SP) > > > > > > Thus, using > > > > > > sun_jvm_hotspot_debugger_x86_X86ThreadContext_SP > > > > > > The Java code uses: > > > > > > sun.jvm.hotspot.debugger.x86.X86ThreadContext.ESP > > > > > > > Also, why is there any code being executed that was not compiled > > > > with > > > > -fno-omit-frame-pointer? The description in the CR just shows a > > > > simple java program reproducing this, so all the mixed stack > > > > traces > > > > belong to the JVM and libs, and I thought we made sure to compile > > > > all > > > > of them with -fno-omit-frame-pointer. > > > > > > The JVM uses glibc and that simple program is enough to see some > > > thread's stack currently being in a glibc function when getting a > > > mixed stack trace. We've originally seen this in JDK 8 with jstack > > > -m > > > and was reported in [2]. That comment has more details. The > > > problem > > > here isn't that it's a JDK lib which gets compiled without > > > -fno-omit-frame- pointer. It's glibc not being compiled with that > > > option. > > > > > > An example stack trace for a system where this happens looks like > > > this: > > > > > > Thread 7 (Thread 0xa3863b40 (LWP 834)): > > > #0 0xf771f430 in __kernel_vsyscall () > > > #1 0xf7703acc in futex_abstimed_wait (cancel=true, > > > private=<optimized > > > out>, abstime=0x0, expected=1, futex=0xf770f000) at > > > ../nptl/sysdeps/unix/sysv/linux/sem_waitcommon.c:43 > > > #2 do_futex_wait (sem=0xf770f000, sem@entry=0xf70ea854 <sig_sem>, > > > abstime=0x0) at > > > ../nptl/sysdeps/unix/sysv/linux/sem_waitcommon.c:226 > > > #3 0xf7703bb7 in __new_sem_wait_slow (sem=0xf70ea854 <sig_sem>, > > > abstime=0x0) at > > > ../nptl/sysdeps/unix/sysv/linux/sem_waitcommon.c:407 > > > #4 0xf6cc18d4 in check_pending_signals (wait=true) at > > > /usr/src/debug/java-1.8.0-openjdk-1.8.0.171- > > > 8.b10.el7_5.i386/openjdk/h > > > otspot/src/os/linux/vm/os_linux.cpp:2522 > > > #5 0xf6cbc632 in signal_thread_entry (thread=0xa37a4800, > > > __the_thread__=0xa37a4800) at > > > /usr/src/debug/java-1.8.0-openjdk-1.8.0.171- > > > 8.b10.el7_5.i386/openjdk/h > > > otspot/src/share/vm/runtime/os.cpp:250 > > > > > > That is, frames 0-3 are JDK foreign. This bug will happen on all > > > systems which use any native library which isn't compiled with > > > -fno- > > > omit-frame-pointer. Be it glibc or some other library. > > > > Ok. It looks like we don't even have a "jstack --mixed" test. Could > > you add one? It would be even better if the test included a JNI lib > > that wasn't compiled with -fno-omit-frame-pointer so you don't need > > to rely on glibc to reproduce this issue (or is glibc pretty much > > always compiled without -fno-omit-frame-pointer)? Or if Sharath > > agrees, file a bug to have a test added. > > > > thanks, > > > > Chris > > > > > > Thanks, > > > Severin > > > > > > [1] https://bugzilla.redhat.com/show_bug.cgi?id=1602008#c9 > > > [2] https://bugzilla.redhat.com/show_bug.cgi?id=1602008#c4 > > > > > > > thanks, > > > > > > > > Chris > > > > > > > > On 7/26/18 10:11 AM, Severin Gehwolf wrote: > > > > > On Thu, 2018-07-26 at 10:04 -0700, Sharath Ballal wrote: > > > > > > Changes looks good Severin. > > > > > > > > > > Thanks for the review, Sharath! > > > > > > > > > > > I am not a reviewer though, so you still need a Reviewer to > > > > > > review. > > > > > > > > > > Anyone? > > > > > > > > > > Thanks, > > > > > Severin > > > > > > > > > > > -----Original Message----- > > > > > > From: Severin Gehwolf [mailto:sgehw...@redhat.com] > > > > > > Sent: Thursday, July 26, 2018 1:04 PM > > > > > > To: serviceability-dev > > > > > > Subject: [PING] RFR(XS): 8208091: SA: jhsdb jstack --mixed > > > > > > throws > > > > > > UnmappedAddressException on i686 > > > > > > > > > > > > On Mon, 2018-07-23 at 18:27 +0200, Severin Gehwolf wrote: > > > > > > > Hi, > > > > > > > > > > > > > > Could I please get a review of this one-liner change > > > > > > > related to > > > > > > > jhsdb --mixed when attaching to a running Java process? The > > > > > > > issue > > > > > > > arises when threads are in native code and that native code > > > > > > > has > > > > > > > frame pointers not properly preserved. In such a case the > > > > > > > SA > > > > > > > performs a simple frame pointer valididy check: ebp >= esp > > > > > > > > > > > > > > However, the code of retrieving the value for esp is > > > > > > > incorrect in > > > > > > > as much as it's not in sync with native code in regards to > > > > > > > the > > > > > > > register > > > > > > > index: > > > > > > > > > > > > > > native code => X86ThreadContext.SP > > > > > > > Java code => X86ThreadContext.ESP > > > > > > > > > > > > > > X86ThreadContext.ESP is never being set by the native code. > > > > > > > Since > > > > > > > X86ThreadContext.getRegisterAsAddress(X86ThreadContext.ESP) > > > > > > > then > > > > > > > returns null, ebp.lessThan(esp) wrongly returns false > > > > > > > causing the > > > > > > > issue. This webrev fixes it by using SP as index on the > > > > > > > Java side. > > > > > > > Thoughts? > > > > > > > > > > > > > > webrev: > > > > > > > > > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8208091/webrev.01 > > > > > > > / > > > > > > > bug: https://bugs.openjdk.java.net/browse/JDK-8208091 > > > > > > > > > > > > Anyone willing to review this one-liner? > > > > > > > > > > > > Thanks, > > > > > > Severin > > > > > > > > > > > > > Thanks, > > > > > > > Severin > > > > > >
