From: N Jain <jain61@gmail.com>
To: musl@lists.openwall.com, Szabolcs Nagy <nsz@port70.net>
Subject: Re: MUSL issue while loading C++ lib
Date: Wed, 27 Jan 2016 14:04:59 -0500 [thread overview]
Message-ID: <CAOkOUee5gw1uVKGT3+X+2+z+c2KZ=FJh=fcYCd3Zni7Jeer2wQ@mail.gmail.com> (raw)
In-Reply-To: <20160121224818.GE9621@port70.net>
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Hi All,
I was debugging and trying to find the issue in MUSL during finding
"_Unwind_Resume_or_Rethrow" symbol.
I see that under find_sym function sysv_lookup(s,h,dso) function it is not
able to get above names which seems to be right as the offset in reloc
section of "libstdc++.so.6" is zero
Example table below -
Offset Info Type Sym.Value Sym.
Name
0013700c 00000516 R_ARM_JUMP_SLOT 000c8bc8
_ZNSt13basic_filebufIcSt11char_traitsIcEE19_M_terminate_outputEv (*Able to
lookup*)
*00137330 00051c16 R_ARM_JUMP_SLOT 00000000 _Unwind_Resume_or_Rethrow
(Failed)*
*00137510 00083616 R_ARM_JUMP_SLOT 00000000 _Unwind_GetLanguageSpe
(Failed)*
> > and i think the linked binary is fine
>
> > libstdc++.so.6 vs libgcc_s.so.1 has some issues
> > which makes the musl linker fail to find some symbols.
>
From above dump I can see if Sym.Value = 0x0 then the symbol lookup fails.
Can some one know how to solve above issue ?
Also I am not able to find the code if libstdc++.so.6 needs dynamic
section libgcc_s.so.1
then by the time MUSL loads libstdc++.so.6 above symbols should not have
Sym.Value = 0x0 ?
>
> > i can't help further, you will have to debug it,
> > i'd try to look at dso->strings with gdb and why the find_sym fails
> > or recompile musl with some dprintf added,
> > or try a known working toolchain and compare against it,
> > or wait for other ideas..
>
Any one know code where if library itself is dependent on other library
where is symbol relocation happening ?
I guess the issue is in that part of MUSL code ? Is there any MUSL patch to
resolve above issue ?
Thanks,
NJ
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next prev parent reply other threads:[~2016-01-27 19:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-21 16:21 N Jain
2016-01-21 17:12 ` Szabolcs Nagy
2016-01-21 19:05 ` N Jain
2016-01-21 20:06 ` Szabolcs Nagy
2016-01-21 21:17 ` N Jain
2016-01-21 22:48 ` Szabolcs Nagy
2016-01-27 19:04 ` N Jain [this message]
2016-01-27 20:08 ` Szabolcs Nagy
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