[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
** Changed in: qt4-x11 (Ubuntu Natty) Milestone: natty-alpha-2 = natty-alpha-3 -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to qt4-x11 in ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
The unity-2d-launcher crash can be reproduced with a locally built Qt, however the app I pasted in comment #9 works. I built Qt with regular system libs and not in a chroot so maybe there's a slight difference. As seen for the sample app, if I built Qt with either g++ or gcc 4.4(there are both C++ and C files in the source) the crash is similar, so I don't think this is a compiler regression. The bug occurs when accessing a volatile int member of a struct via an int() operator defined on that class and which simply returns the value. QBasicAtomicInt class in this file http://qt.gitorious.org/qt/qt/blobs/4.7/src/corelib/thread/qbasicatomic.h The two crashes I have seen both access that field from within the macro Q_DECLARE_METATYPE at line 265 in http://qt.gitorious.org/qt/qt/blobs/4.7/src/corelib/kernel/qmetatype.h That macro is used to define GestureState metatype, the one seen in the stacktraces above. I'll try to check whether https://bugs.launchpad.net/gcc- linaro/+bug/675347 is related. -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to qt4-x11 in ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
When disassembling the 10.10 Qt library which has ittt no warning is given, so that was probably a false trail, sorry. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
Yeah, I'm agreeing with Jani, that was a false trail. here's the new backtrace with ittt in the patch and unity-2d rebuilt against it: (gdb) bt #0 0x404fce2c in operator int (this=0xdf6ce0, parent=value optimized out) at ../../include/QtCore/../../src/corelib/thread/qbasicatomic.h:85 #1 qt_metatype_id (this=0xdf6ce0, parent=value optimized out) at ../../include/QtGui/private/../../../src/gui/kernel/qgesture.h:56 #2 qt_metatype_id (this=0xdf6ce0, parent=value optimized out) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:169 #3 qMetaTypeIdQt::GestureState (this=0xdf6ce0, parent=value optimized out) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:230 #4 qRegisterMetaTypeQt::GestureState (this=0xdf6ce0, parent=value optimized out) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:243 #5 QGestureManager::QGestureManager (this=0xdf6ce0, parent=value optimized out) at kernel/qgesturemanager.cpp:76 #6 0x404c108a in QGestureManager::instance () at kernel/qapplication.cpp:5849 #7 0x404f0f0e in QWidget::grabGesture (this=value optimized out, gesture=Qt::PanGesture, flags=...) at kernel/qwidget.cpp:12079 #8 0x4079aba8 in QAbstractScrollAreaPrivate::init (this=0xddfd20) at widgets/qabstractscrollarea.cpp:299 #9 0x4079ac58 in QAbstractScrollArea::QAbstractScrollArea ( this=0xbeac75ac, dd=value optimized out, parent=value optimized out) at widgets/qabstractscrollarea.cpp:493 #10 0x40893aac in QGraphicsView::QGraphicsView (this=0xbeac75ac, dd=value optimized out, parent=value optimized out) at graphicsview/qgraphicsview.cpp:1146 #11 0x40a96e4e in QDeclarativeView::QDeclarativeView (this=0xbeac75ac, parent=0x0) at util/qdeclarativeview.cpp:254 #12 0xcc76 in LauncherView::LauncherView() () #13 0xc2dc in main () -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to qt4-x11 in ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
So after active debugging on #linaro, I tore apart some maverick binaries built against stock-maverick qt4-x11, which has implicate-its enabled, and found the compiler generated an 'i' instruciton vs 'ittt'. I'm currently testbuilding a new version of Qt with this modification. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
Test code on maverick (no explicate it block):
mcasadevall@risingsun:/srv/chroots/maverick-armel$ cat test.c
#include stdio.h
int _q_value = 10;
inline bool testAndSetOrdered(int expectedValue, int newValue)
{
register int result;
asm volatile(0:\n
ldrex %[result], [%[_q_value]]\n
eors %[result], %[result], %[expectedValue]\n
strexeq %[result], %[newValue], [%[_q_value]]\n
teqeq %[result], #1\n
beq 0b\n
: [result] =r (result),
+m (_q_value)
: [expectedValue] r (expectedValue),
[newValue] r (newValue),
[_q_value] r (_q_value)
: cc, memory);
return result == 0;
}
int main() {
return testAndSetOrdered(1, 1);
}
Relevant disassembly from objdump:
8378 _Z17testAndSetOrderedii:
8378: b490push{r4, r7}
837a: b082sub sp, #8
837c: af00add r7, sp, #0
837e: 6078str r0, [r7, #4]
8380: 6039str r1, [r7, #0]
8382: f241 0124 movwr1, #4132 ; 0x1024
8386: f2c0 0101 movtr1, #1
838a: 6878ldr r0, [r7, #4]
838c: f8d7 c000 ldr.w ip, [r7]
8390: f241 0324 movwr3, #4132 ; 0x1024
8394: f2c0 0301 movtr3, #1
8398: f241 0224 movwr2, #4132 ; 0x1024
839c: f2c0 0201 movtr2, #1
83a0: e853 4f00 ldrex r4, [r3]
83a4: 4044eorsr4, r0
83a6: bf02ittteq
83a8: e843 c400 strexeq r4, ip, [r3]
83ac: f094 0f01 teqeq r4, #1
83b0: e7f6beq.n 83a0 _Z17testAndSetOrderedii+0x28
83b2: 2c00cmp r4, #0
83b4: bf14ite ne
83b6: 2300movne r3, #0
83b8: 2301moveq r3, #1
83ba: b2dbuxtbr3, r3
83bc: 4618mov r0, r3
83be: f107 0708 add.w r7, r7, #8
83c2: 46bdmov sp, r7
83c4: bc90pop {r4, r7}
83c6: 4770bx lr
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Title:
unity-2d-launcher crashes with segfault error on armel (natty only)
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[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
An alternatve to rebuilding Qt with the patch applied is to binary patch the Qt libs and test: I copied libQtCore.so and libQtGui.so (the two Qt deps of the simple Qt app which crashes) in the current dir Then sed -i 's/\x04\(\xbf.\xe8\x00.\)/\x02\1/' libQtCore.so.4 same on QtGui export LD_LIBRARY_PATH=. ldd ./crasherapp (just to confirm it ineed gets the libs from the current dir) This sed invocation changes itt to ittt in the places where a strexeq follows The app crashes in the same way so unlikely imho that the patch is the issue, or that indeed the patch is incorrect. With ittt objdump -d annotates that disas line with beq.n 1242c8 _ZN12QApplication11qt_metacastEPKc+0x5c; unpredictable IT:eq because it is unclear whether the ittt of the previous teq should affect the conditional bits in the beqeq instruction -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to qt4-x11 in ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
Hi Jani, Assuming for the moment that sed didn't trip over any other matching chunk of binary, ok, but It's not clear to me why the assembler is warning on that branch; can you disassemble the 4 or 5 instructions leading up to that? My reading of binutils is that it prints that message for a branch that is not the last element of an IT block, and in the original code quoted the branch should be the last one. I don't see anything that marks unpredictability due to the shadow of a teq; and I don't see anything in the ARM ARM that says it's unpredictable. Dave -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
Definitely not a unity-2d bug :)
This simple app build on pandaboard and current natty crashes in the same way
as the launcher (in QReadUnlock())
Crashes 4 runs out of 5 maybe, built with either g++-4.4 or g++4.5
//to build: c++ -I/usr/include/qt4 -I/usr/include/qt4/QtGui
crashercpp -lQtGui -o crasher
#include qapplication.h
int main(int argc, char *argv[]) {
QApplication a(argc, argv);
return 0;
}
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Title:
unity-2d-launcher crashes with segfault error on armel (natty only)
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[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
Did another round of tests, with maverick build 4.7.0 with the natty IT patch added (posted above) and I got a segfault similar to the one we got earlier, which leads me to believe we have a bad patch. Backtrace is identical to current faults. Looks like this is a bad patch to Qt vs. a gcc regression; closing gcc task. ** Changed in: gcc-4.5 (Ubuntu Natty) Status: New = Invalid -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to qt4-x11 in ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
** Also affects: gcc-4.5 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
Opening new task on gcc-4.5 due to possibility of compiler regression. Attempting to build natty's Qt on maverick caused a compiler ICE, but since I was building in sbuild, I lost the build environment when it failed. Will try and rerun build at some point so I can file that bug. I was pointed at unit tests for Qt, so I'm going to run the suite and see if we can isolate the specific problem areas. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
On a hunch that we're looking at a possible compiler regression, I recompiled the maverick Qt 4.7.0 source package against natty (and added the thumb2 patch attached below from the 4.7.1 package) and installed it on a working natty system which still developed a segfault. Backtrace with 4.7.0 built on natty. Program received signal SIGSEGV, Segmentation fault. 0x404695ba in operator int (this=0xe0ab10, parent=value optimized out) at ../../include/QtCore/../../src/corelib/thread/qbasicatomic.h:85 85 return _q_value; (gdb) bt #0 0x404695ba in operator int (this=0xe0ab10, parent=value optimized out) at ../../include/QtCore/../../src/corelib/thread/qbasicatomic.h:85 #1 qt_metatype_id (this=0xe0ab10, parent=value optimized out) at ../../include/QtGui/private/../../../src/gui/kernel/qgesture.h:56 #2 qt_metatype_id (this=0xe0ab10, parent=value optimized out) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:222 #3 qMetaTypeIdQt::GestureState (this=0xe0ab10, parent=value optimized out) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:232 #4 qRegisterMetaTypeQt::GestureState (this=0xe0ab10, parent=value optimized out) at ../../include/QtCore/../../src/corelib/kernel/qmetatype.h:245 #5 QGestureManager::QGestureManager (this=0xe0ab10, parent=value optimized out) at kernel/qgesturemanager.cpp:76 #6 0x4042e0d2 in QGestureManager::instance () at kernel/qapplication.cpp:5798 #7 0x4045dece in QWidget::grabGesture (this=value optimized out, gesture=Qt::PanGesture, flags=...) at kernel/qwidget.cpp:12066 #8 0x40705d18 in QAbstractScrollAreaPrivate::init (this=0xe1f4c0) at widgets/qabstractscrollarea.cpp:299 #9 0x40705dc8 in QAbstractScrollArea::QAbstractScrollArea ( this=0xbe8d65b0, dd=value optimized out, parent=value optimized out) at widgets/qabstractscrollarea.cpp:493 #10 0x407ff78c in QGraphicsView::QGraphicsView (this=0xbe8d65b0, dd=value optimized out, parent=value optimized out) at graphicsview/qgraphicsview.cpp:1146 #11 0x40a07a8e in QDeclarativeView::QDeclarativeView (this=0xbe8d65b0, parent=0x0) at util/qdeclarativeview.cpp:254 #12 0xc796 in LauncherView::LauncherView() () #13 0xc050 in main () mcasadevall@risingsun:~$ cat src/qt4-x11-4.7.0/debian/patches/kubuntu_22_thumb2_support.diff Provide Thumb2 support on armel - See LP Bug #673085 for details Index: qt-everywhere-opensource-src-4.7.1/src/corelib/arch/qatomic_armv6.h === --- qt-everywhere-opensource-src-4.7.1.orig/src/corelib/arch/qatomic_armv6.h2010-11-06 01:55:18.0 + +++ qt-everywhere-opensource-src-4.7.1/src/corelib/arch/qatomic_armv6.h 2010-11-16 17:58:27.831286420 + @@ -144,6 +144,7 @@ asm volatile(0:\n ldrex %[result], [%[_q_value]]\n eors %[result], %[result], %[expectedValue]\n + itt eq\n strexeq %[result], %[newValue], [%[_q_value]]\n teqeq %[result], #1\n beq 0b\n @@ -202,6 +203,7 @@ asm volatile(0:\n ldrex %[result], [%[_q_value]]\n eors %[result], %[result], %[expectedValue]\n + itt eq\n strexeq %[result], %[newValue], [%[_q_value]]\n teqeq %[result], #1\n beq 0b\n Will attempt building natty's Qt on maverick to confirm compiler regression. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 705689] Re: unity-2d-launcher crashes with segfault error on armel (natty only)
** Also affects: qt4-x11 (Ubuntu Natty) Importance: High Assignee: Michael Casadevall (mcasadevall) Status: Confirmed ** Changed in: unity-2d Status: New = Invalid ** Changed in: qt4-x11 (Ubuntu Natty) Milestone: None = natty-alpha-2 ** Changed in: unity-2d Importance: Critical = High -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to qt4-x11 in ubuntu. https://bugs.launchpad.net/bugs/705689 Title: unity-2d-launcher crashes with segfault error on armel (natty only) -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
