Date: Mon, 28 May 2018 17:38:21 +0000 From: bugzilla-noreply@freebsd.org To: ports-bugs@FreeBSD.org Subject: [Bug 225128] [exp-run] with LLD_BOOTSTRAP on i386 Message-ID: <bug-225128-7788-sV2RVKde1G@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-225128-7788@https.bugs.freebsd.org/bugzilla/> References: <bug-225128-7788@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D225128 Mark Johnston <markj@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |markj@FreeBSD.org --- Comment #25 from Mark Johnston <markj@FreeBSD.org> --- (In reply to Antoine Brodin from comment #23) I partially diagnosed the issue with nntpcache (which also seems to occur on amd64). The issue is around the _end symbol, which marks the end of the .bss section. When libc.so is linked with GNU ld, the _end symbol's section inde= x is SHN_ABS (i.e., the symbol value is not affected by relocations). When it's linked with lld, _end's section index is that of .bss. When linking an executable against an lld-linked libc.so, GNU ld does not include _end in t= he executable's dynamic symbol table. The crash then occurs because the execut= able uses sbrk(3), curbrk is initialized to &_end, and because the executable do= es not export _end, libc initializes curbrk to the address of its own internal _end symbol, which is wrong. The problem occurs when linking an executable = with ld from binutils 2.30 as well. I hacked lld to emit _end with a shndx of SHN_ABS, and when using a libc compiled with that hack I can compile news/nntpcache. I have not been able = to reproduce the other build failures so far. I'm having trouble figuring out why GNU ld refuses to emit _end in this scenario. _end is synthesized using the system linker scripts, and I haven't been able to figure out exactly what logic is causing it to be excluded. It seems incorrect that GNU ld using SHN_ABS this way in the first place: obviously the value of _end is going to be modified by a relocation when libc.so is loaded. --=20 You are receiving this mail because: You are on the CC list for the bug.=
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