GAS fix for reloc problems (was Re: [parisc-linux] Non-bootable kernel problems)
14 Jul 2000 18:14:15 -0400
David Huggins-Daines <email@example.com> writes:
> David Huggins-Daines <firstname.lastname@example.org> writes:
> > Jeffrey A Law <email@example.com> writes:
> > > Either we need to avoid merging the section symbols to avoid twiddling
> > > the addend, or we need to avoid reducing relocs to section symbols to
> > > begin with.
> Okay, I'll investigate this approach.
Done. PA-RISC porters, update your binutils-2.10 and GCC. (again :-)
Here's the patch, which I've committed to puffin CVS (I've
reverted the incorrect GCC changes):
2000-07-14 David Huggins-Daines <firstname.lastname@example.org>
* config/tc-hppa.c (hppa_fix_adjustable): Reject reductions of
sym-sym2 expressions as well as LR% and RR% fields on ELF targets
RCS file: /home/cvs/parisc/binutils-2.10/gas/config/tc-hppa.c,v
retrieving revision 1.12
retrieving revision 1.13
diff -u -r1.12 -r1.13
--- tc-hppa.c 2000/07/11 14:02:15 1.12
+++ tc-hppa.c 2000/07/14 21:48:42 1.13
@@ -8369,10 +8369,25 @@
/* Reject reductions of symbols in 32bit relocs. */
if (fixp->fx_r_type == R_HPPA && hppa_fix->fx_r_format == 32)
/* Reject reductions of symbols in sym1-sym2 expressions when
the fixup will occur in a CODE subspace.
+ NOTE: We want to reject these for ELF targets as well, because
+ otherwise we will lose in the case of 21L and 14R
+ relocations. (FIXME: will this break ELF64 targets?)
+ This is because, since the symbols are reduced, the linker has no
+ choice but to manipulate the addends when coalescing input .data
+ sections. Because the 32-bit ABI requires the compiler to
+ pre-round LR% field selectors, this means we end up with
+ different addends for the left and right relocations. Because of
+ the way LR% and RR% field selectors work, it's possible that the
+ RR% field will turn negative without the LR% field being rounded
+ accordingly, and your Linux kernel crashes mysteriously.
+ - email@example.com, 2000-07-14
XXX FIXME: Long term we probably want to reject all of these;
for example reducing in the debug section would lose if we ever
supported using the optimizing hp linker. */
@@ -8386,12 +8401,14 @@
/* We can't adjust any relocs that use LR% and RR% field selectors.
- That confuses the HP linker. */
+ That confuses the HP linker.
+ FIXME: do we actually need to do this for ELF32/GNU ld as well?
+ What about ELF64? */
if (hppa_fix->fx_r_field == e_lrsel
|| hppa_fix->fx_r_field == e_rrsel
|| hppa_fix->fx_r_field == e_nlrsel)
/* Reject reductions of symbols in DLT relative relocs,
relocations with plabels. */
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