s390: Avoid reloc overflows on undefined weak symbols (cont)

This complements and reuses logic from Andreas Krebbel's commit
896a639babe2 ("s390: Avoid reloc overflows on undefined weak symbols").

Replace relative long addressing instructions of weak symbols, which
will definitely resolve to zero, with either a load address of 0 or a
a trapping insn.

This prevents the PLT32DBL relocation from overflowing in case the
binary will be loaded at 4GB or more.

bfd/
	* elf64-s390.c (elf_s390_relocate_section): Replace
	instructions using undefined weak symbols with relative
	addressing to avoid relocation overflows.

ld/
	* testsuite/ld-s390/s390.exp: Add new test.
	* testsuite/ld-s390/weakundef-2.s: New test.
	* testsuite/ld-s390/weakundef-2.dd: Likewise.

Reported-by: Alexander Gordeev <agordeev@linux.ibm.com>
Suggested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Suggested-by: Andreas Krebbel <krebbel@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
4 files changed