Bug 59107 – [Qt] Unaligned access error on browser application with SH4 CPU

• Component: WebKit Qt
• Status: RESOLVED INVALID

[Franck Lamotte]

Created attachment 90542 [details]
the backtrace of callstack.

I have got an unaligned access error with browser application (stored in demos directory) on my sh4 board (linux kernel).

Actions :
- installer qt-everywhere-opensource-src (4.7.2)
- Compiled qt-everywhere-opensource-src with STlinux 2.3 toolchain in debug mode (qtwebkit-debug) (=> for SH4 board)
- run the "browser -qws" app from "demos" directory

I got the following error :
Unaligned userspace access in "browser" pid=6590 pc=0x2a1313c0 ins=0x6112

Informations :
configure -embedded sh -xplatform qws/linux-sh4-g++ -debug -fast -little-endian -opensource -no-exceptions -no-accessibility -no-stl -no-qt3support -no-xmlpatterns -no-multimedia -no-audio-backend -no-phonon -no-svg -webkit-debug -no-javascript-jit -script -scripttools -declarative -qt-zlib -qt-gif 
-no-libtiff -system-libpng -qt-libmng -system-libjpeg -openssl -no-nis -no-cups -no-iconv -no-pch -reduce-relocations -no-gtkstyle -no-nas-sound -no-sm 
-no-xshape -no-xsync -no-xinerama  -no-xcursor -no-xfixes -no-xrandr -no-xrender -no-mitshm -no-fontconfig -no-xinput -no-xkb -no-glib -qt-gfx-directfb -prefix . 
-prefix-install -rpath -qvfb -confirm-license -R . -no-separate-debug-info -L$LIBTARGET -L$DLLTARGET -nomake examples -nomake demos -nomake docs


The crash is systematic. I do not edit the source code.

I use QTWebkit 2.0.

[Benjamin Poulain]

Given none of us have the hardware it is very unlikely we fix that.

The trange thing is the stack does not involve JavaScript, it is just pure c++ function stack. Given that, you should have a look at:
-is this a compiler bug? Do the instructions make sense?
-is one of the library compiled with different stack alignment?

[Franck Lamotte]

Thanks for reply.
I have tested with an updated version of STlinux 2.3 toolchain and it works better, for the moment no more unaligment error.

But i have one with my application (investigations in progress ...).

Franck

[Benjamin Poulain]

(In reply to comment #2)
> I have tested with an updated version of STlinux 2.3 toolchain and it works better, for the moment no more unaligment error.
> 
> But i have one with my application (investigations in progress ...).

Ok, I close the bug here then, no point at tracking a bug in WebKit for compiler issues.
You can still comment if you find new info and if the bug should be reopened.

[ssseintr]

Hi,

Can you please tell the compiler & binutils version in which you have the problem..?

Since we too having the same kind of problem, we just removed -ffuntion-section & -fdata-section from CFLAGS & --gc-section from LDFLAGS.

Regards,
Vicky

[Konstantin Tokarev]

ssseintr: Thank you very much for your advice! I've experienced the same problem with STLinux2.3 toolchain, and your solution works perfectly.

Here is my patch (not sure if it should be submitted to main tree though):

diff --git a/WebCore/WebCore.pro b/WebCore/WebCore.pro
index 46d0db8..ccf87d1 100644
--- a/WebCore/WebCore.pro
+++ b/WebCore/WebCore.pro
@@ -90,8 +90,8 @@ unix {
     QMAKE_PKGCONFIG_REQUIRES = QtCore QtGui QtNetwork
 }
 
-unix:!mac:*-g++*:QMAKE_CXXFLAGS += -ffunction-sections -fdata-sections 
-unix:!mac:*-g++*:QMAKE_LFLAGS += -Wl,--gc-sections
+unix:!mac:*-g++*:!*-sh4-*:QMAKE_CXXFLAGS += -ffunction-sections -fdata-sections 
+unix:!mac:*-g++*:!*-sh4-*:QMAKE_LFLAGS += -Wl,--gc-sections
 linux*-g++*:QMAKE_LFLAGS += $$QMAKE_LFLAGS_NOUNDEF
 
 CONFIG(release):!CONFIG(standalone_package) {