Date: Wed, 11 Jan 2017 22:06:58 +0100 From: Roman Divacky <rdivacky@vlakno.cz> To: Mark Millard <markmi@dsl-only.net> Cc: FreeBSD Toolchain <freebsd-toolchain@freebsd.org> Subject: Re: /usr/bin/ld.lld on powerpc64: produces a.out for which: ld-elf.so.1: assert failed: /usr/src/libexec/rtld-elf/powerpc64/reloc.c:374 Message-ID: <20170111210658.GA20265@vlakno.cz> In-Reply-To: <8242A7B9-7ED3-4861-8209-F3728113D188@dsl-only.net> References: <7139F615-8F18-4EDC-9051-5FFEC0C4057F@dsl-only.net> <CAPyFy2CSmNyUjQcXyq4qUWp_A=Qr81O7fpRbZ5GcfFHFhdSntw@mail.gmail.com> <CF2D86C8-8EEB-4536-8D83-6F8C676EFEF6@dsl-only.net> <20170111194844.GA16135@vlakno.cz> <8242A7B9-7ED3-4861-8209-F3728113D188@dsl-only.net>
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Looks like a progress :) Three questions...
Is the readelf -a reasonable now? If you compile with -g, does the
backtrace make a bit more sense? And finally, can you try to "nexti/stepi" in gdb from
_start to see where things go wrong? Possibly doing it both for ld linked a.out
and lld linked a.out and compare where things differ.
Thanks! Roman
On Wed, Jan 11, 2017 at 12:37:52PM -0800, Mark Millard wrote:
> On 2017-Jan-11, at 11:48 AM, Roman Divacky <rdivacky at vlakno.cz> wrote:
>
> > Can you try this patch?
> >
> > Index: tools/lld/ELF/Target.cpp
> > ===================================================================
> > --- tools/lld/ELF/Target.cpp (revision 291691)
> > +++ tools/lld/ELF/Target.cpp (working copy)
> > @@ -1062,7 +1062,8 @@
> > }
> >
> > PPC64TargetInfo::PPC64TargetInfo() {
> > - PltRel = GotRel = R_PPC64_GLOB_DAT;
> > + GotRel = R_PPC64_GLOB_DAT;
> > + PltRel = R_PPC64_JMP_SLOT;
> > RelativeRel = R_PPC64_RELATIVE;
> > GotEntrySize = 8;
> > GotPltEntrySize = 8;
>
> The result for the generated a.out (via ld.lld) was:
>
> # /usr/local/bin/gdb a.out
> . . .
> Reading symbols from a.out...done.
> (gdb) run
> Starting program: /root/c_tests/a.out
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x000000001001056c in ?? ()
> (gdb) bt
> #0 0x000000001001056c in ?? ()
> #1 0x00000000100100d8 in ?? ()
> #2 0x00000000500279e0 in ._rtld_start () at /usr/src/libexec/rtld-elf/powerpc64/rtld_start.S:104
> Backtrace stopped: frame did not save the PC
>
>
> ===
> Mark Millard
> markmi at dsl-only.net
>
>
> On Wed, Jan 11, 2017 at 09:47:34AM -0800, Mark Millard wrote:
> >
> > On 2017-Jan-11, at 8:07 AM, Ed Maste <emaste at freebsd.org> wrote:
> >
> >> On 11 January 2017 at 04:15, Mark Millard <markmi at dsl-only.net> wrote:
> >>>
> >>> # ./a.out
> >>> ld-elf.so.1: assert failed: /usr/src/libexec/rtld-elf/powerpc64/reloc.c:374
> >>> Abort trap (core dumped)
> >>
> >> Would you paste the output of `readelf -r a.out`?
> >
> > Here you go, for ld.lld and for ld.bfd . . .
> >
> > For -fuse-ld=lld :
> >
> > # readelf -r a.out
> >
> > Relocation section with addend (.rela.plt):
> > r_offset r_info r_type st_value st_name + r_addend
> > 000010030038 000300000014 <unknown: 0x14> 0000000000000000 atexit + 0
> > 000010030040 000200000014 <unknown: 0x14> 0000000000000000 _init_tls + 0
> > 000010030048 000500000014 <unknown: 0x14> 0000000000000000 exit + 0
> >
> > For -fuse-ld=bfd :
> >
> > # readelf -r a.out
> >
> > Relocation section with addend (.rela.plt):
> > r_offset r_info r_type st_value st_name + r_addend
> > 000010010cb8 000300000015 <unknown: 0x15> 0000000000000000 atexit + 0
> > 000010010cd0 000400000015 <unknown: 0x15> 0000000000000000 _init_tls + 0
> > 000010010ce8 000600000015 <unknown: 0x15> 0000000000000000 exit + 0
> >
> > These were done on the powerpc64 machine (native).
> >
> >
> > ===
> > Mark Millard
> > markmi at dsl-only.net
> > _______________________________________________
> > freebsd-toolchain@freebsd.org mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain
> > To unsubscribe, send any mail to "freebsd-toolchain-unsubscribe@freebsd.org"
>
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