The seed binary segfaults when run with webkitgtk3 javascript engine built with gcc6. The segfault goes away when webkitgtk3 is built with -O0. More details will follow, but due to the size of webkit it can take some time. [sharkcz@devel10 ~]$ gdb seed GNU gdb (GDB) Fedora 7.11-59.fc24 Copyright (C) 2016 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "s390x-redhat-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from seed...Reading symbols from /usr/lib/debug/usr/bin/seed.debug...done. done. (gdb) run Starting program: /usr/bin/seed Missing separate debuginfos, use: dnf debuginfo-install glibc-2.23.1-5.fc24.s390x [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". [New Thread 0x3fffaafd910 (LWP 2370)] [New Thread 0x3fff9ff9910 (LWP 2371)] Thread 1 "seed" received signal SIGSEGV, Segmentation fault. WTF::String::isolatedCopy (this=0x8, this@entry=0x3fffa1ff5b8) at Source/WTF/wtf/text/WTFString.cpp:682 682 if (!m_impl) Missing separate debuginfos, use: dnf debuginfo-install glib2-2.47.6.19.gad2092b-2.fc24.s390x gobject-introspection-1.47.1-3.fc24.s390x libffi-3.1-9.fc24.s390x libgcc-6.0.0-0.15.fc24.s390x libicu-56.1-3.fc24.s390x libselinux-2.5-2.fc24.s390x libstdc++-6.0.0-0.15.fc24.s390x pcre-8.38-11.fc24.s390x zlib-1.2.8-10.fc24.s390x (gdb) where #0 0x000003fffd7cf4ec in WTF::String::isolatedCopy() const (this=0x8, this@entry=0x3fffa1ff5b8) at Source/WTF/wtf/text/WTFString.cpp:682 #1 0x000003fffd434fc2 in OpaqueJSString::string() const (this=this@entry=0x3fffa1ff5b0) at Source/JavaScriptCore/API/OpaqueJSString.cpp:62 #2 0x000003fffd407bda in JSEvaluateScript(JSContextRef, JSStringRef, JSObjectRef, JSStringRef, int, JSValueRef*) (ctx=<optimized out>, script=0x20, thisObject=0x0, sourceURL=0x3fffa1ff5b0, startingLineNumber=1, exception=0x0) at Source/JavaScriptCore/API/JSBase.cpp:60 #3 0x000003fffdc8e77a in seed_simple_evaluate (ctx=0x3fffde5f9b0, source=<optimized out>, exception=0x0) at seed-api.c:305 #4 0x000003fffdc9324a in seed_init_constrained_with_context_and_group (argc=0x3fffffff1ec, argv=0x3fffffff1e0, context=0x3fffde5f9b0, group=0x3fffa201000) at seed-engine.c:1734 #5 0x000003fffdc93526 in seed_init_with_context_and_group (argc=0x3fffffff1ec, argv=0x3fffffff1e0, context=<optimized out>, group=<optimized out>) at seed-engine.c:1792 #6 0x000002aa000014c2 in main (argc=1, argv=0x3fffffff428) at main.c:152 (gdb) l 677 return m_impl->isolatedCopy(); 678 } 679 #else 680 String String::isolatedCopy() const 681 { 682 if (!m_impl) 683 return String(); 684 return m_impl->isolatedCopy(); 685 } 686 #endif (gdb) disas Dump of assembler code for function WTF::String::isolatedCopy() const: 0x000003fffd7cf4c8 <+0>: stmg %r11,%r15,88(%r15) 0x000003fffd7cf4ce <+6>: ear %r1,%a0 0x000003fffd7cf4d2 <+10>: lay %r15,-176(%r15) 0x000003fffd7cf4d8 <+16>: lgr %r11,%r2 0x000003fffd7cf4dc <+20>: sllg %r1,%r1,32 0x000003fffd7cf4e2 <+26>: ear %r1,%a1 0x000003fffd7cf4e6 <+30>: mvc 168(8,%r15),40(%r1) => 0x000003fffd7cf4ec <+36>: ltg %r1,0(%r3) 0x000003fffd7cf4f2 <+42>: je 0x3fffd7cf586 <WTF::String::isolatedCopy() const+190> 0x000003fffd7cf4f6 <+46>: l %r2,24(%r1) 0x000003fffd7cf4fa <+50>: tmll %r2,3 0x000003fffd7cf4fe <+54>: je 0x3fffd7cf556 <WTF::String::isolatedCopy() const+142> 0x000003fffd7cf502 <+58>: tmll %r2,32 0x000003fffd7cf506 <+62>: jne 0x3fffd7cf5bc <WTF::String::isolatedCopy() const+244> 0x000003fffd7cf50a <+66>: llgf %r4,4(%r1) 0x000003fffd7cf510 <+72>: lg %r3,8(%r1) 0x000003fffd7cf516 <+78>: la %r2,160(%r15) 0x000003fffd7cf51a <+82>: brasl %r14,0x3fffd3f1d70 <_ZN3WTF10StringImpl6createEPKtj@plt> 0x000003fffd7cf520 <+88>: lg %r1,160(%r15) 0x000003fffd7cf526 <+94>: stg %r1,0(%r11) 0x000003fffd7cf52c <+100>: ear %r1,%a0 0x000003fffd7cf530 <+104>: lgr %r2,%r11 0x000003fffd7cf534 <+108>: sllg %r1,%r1,32 0x000003fffd7cf53a <+114>: ear %r1,%a1 0x000003fffd7cf53e <+118>: clc 168(8,%r15),40(%r1) 0x000003fffd7cf544 <+124>: jne 0x3fffd7cf5d6 <WTF::String::isolatedCopy() const+270> 0x000003fffd7cf548 <+128>: lg %r4,288(%r15) 0x000003fffd7cf54e <+134>: lmg %r11,%r15,264(%r15) 0x000003fffd7cf554 <+140>: br %r4 0x000003fffd7cf556 <+142>: tmll %r2,32 0x000003fffd7cf55a <+146>: je 0x3fffd7cf594 <WTF::String::isolatedCopy() const+204> 0x000003fffd7cf55e <+150>: la %r2,32(%r1) 0x000003fffd7cf562 <+154>: cg %r2,8(%r1) 0x000003fffd7cf568 <+160>: je 0x3fffd7cf5bc <WTF::String::isolatedCopy() const+244> 0x000003fffd7cf56c <+164>: llgf %r4,4(%r1) 0x000003fffd7cf572 <+170>: lg %r3,8(%r1) 0x000003fffd7cf578 <+176>: la %r2,160(%r15) 0x000003fffd7cf57c <+180>: brasl %r14,0x3fffd3f5510 <_ZN3WTF10StringImpl20createWithoutCopyingEPKhj@plt> 0x000003fffd7cf582 <+186>: j 0x3fffd7cf520 <WTF::String::isolatedCopy() const+88> 0x000003fffd7cf586 <+190>: lghi %r1,0 0x000003fffd7cf58a <+194>: stg %r1,0(%r2) 0x000003fffd7cf590 <+200>: j 0x3fffd7cf52c <WTF::String::isolatedCopy() const+100> 0x000003fffd7cf594 <+204>: la %r2,32(%r1) 0x000003fffd7cf598 <+208>: cg %r2,8(%r1) 0x000003fffd7cf59e <+214>: je 0x3fffd7cf50a <WTF::String::isolatedCopy() const+66> 0x000003fffd7cf5a2 <+218>: llgf %r4,4(%r1) 0x000003fffd7cf5a8 <+224>: lg %r3,8(%r1) 0x000003fffd7cf5ae <+230>: la %r2,160(%r15) ---Type <return> to continue, or q <return> to quit--- 0x000003fffd7cf5b2 <+234>: brasl %r14,0x3fffd3f8710 <_ZN3WTF10StringImpl20createWithoutCopyingEPKtj@plt> 0x000003fffd7cf5b8 <+240>: j 0x3fffd7cf520 <WTF::String::isolatedCopy() const+88> 0x000003fffd7cf5bc <+244>: llgf %r4,4(%r1) 0x000003fffd7cf5c2 <+250>: lg %r3,8(%r1) 0x000003fffd7cf5c8 <+256>: la %r2,160(%r15) 0x000003fffd7cf5cc <+260>: brasl %r14,0x3fffd3e8e90 <_ZN3WTF10StringImpl6createEPKhj@plt> 0x000003fffd7cf5d2 <+266>: j 0x3fffd7cf520 <WTF::String::isolatedCopy() const+88> 0x000003fffd7cf5d6 <+270>: brasl %r14,0x3fffd3f8230 <__stack_chk_fail@plt> End of assembler dump. (gdb) Version-Release number of selected component (if applicable): seed-3.8.1-6.fc23.s390x webkitgtk3-2.4.10-1.fc24.s390x gcc-6.0.0-0.16.fc24.s390x (used to rebuild webkit)
Does -fno-delete-null-pointer-checks and/or -fno-lifetime-dse (or -flifetime-dse=1) help? Lot of the larger C++ packages are just buggy, call methods on NULL pointers or assume ctors can preserve data from e.g. allocator new in the object.
this=0x8 definitely suggests a null pointer dereference, so yet another -fdelete-null-pointer-checks case.
yes, these are on the list of things to try, but webkit builds times are in many hours, so stay tuned
After a rebuild with -fno-delete-null-pointer-checks there is no more a segfault in seed. If I understand the problem correctly, it means webkit contains buggy code.
it also segfaults on ppc, rebuild it with -fno-delete-null-pointer-checks fix the issue.
I committed a workaround [0] for the webkitgtk and webkitgtk3 packages in F24 and rawhide. The build's nvr is webkitgtk(3)-2.4.10-2.fc(24|25) [0] - pkgs.fedoraproject.org/cgit/rpms/webkitgtk3.git/commit/?id=d95fe12
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