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S/390: Prevent GOT access rewrite for certain symbols
When dereferencing a GOT slot with lgrl or lg we rewrite this using larl to get rid of the extra memory access. However, we cannot do this for: - symbols marked for absolute addressing - symbols at odd addresses (larl can handle only even addresses) Fixed with the attached patch. bfd/ChangeLog: 2018-09-17 Andreas Krebbel <krebbel@linux.ibm.com> * elf64-s390.c (elf_s390_relocate_section): Prevent rewriting of GOT accesses with larl for ABS or misaligned symbols. ld/ChangeLog: 2018-09-17 Andreas Krebbel <krebbel@linux.ibm.com> * testsuite/ld-s390/gotreloc-1.s: Add tests for ABS and misaligned symbol. Move variables into data section. Make bar 8 bytes wide. * testsuite/ld-s390/gotreloc-1.ver: Make misaligned_sym resolve locally. * testsuite/ld-s390/gotreloc_31-1.dd: Adjust patterns. * testsuite/ld-s390/gotreloc_64-norelro-1.dd: Likewise. * testsuite/ld-s390/gotreloc_64-relro-1.dd: Likewise.
This commit is contained in:
Andreas Krebbel
Andreas Krebbel
parent
cb5248409d
commit
e6213e09ed
@ -2341,6 +2341,9 @@ elf_s390_relocate_section (bfd *output_bfd,
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&& SYMBOL_REFERENCES_LOCAL (info, h))
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|| resolved_to_zero)
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{
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Elf_Internal_Sym *isym;
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asection *sym_sec;
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/* This is actually a static link, or it is a
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-Bsymbolic link and the symbol is defined
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locally, or the symbol was forced to be local
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@ -2362,6 +2365,10 @@ elf_s390_relocate_section (bfd *output_bfd,
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h->got.offset |= 1;
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}
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/* When turning a GOT slot dereference into a direct
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reference using larl we have to make sure that
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the symbol is 1. properly aligned and 2. it is no
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ABS symbol or will become one. */
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if ((h->def_regular
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&& bfd_link_pic (info)
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&& SYMBOL_REFERENCES_LOCAL (info, h))
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@ -2376,8 +2383,17 @@ elf_s390_relocate_section (bfd *output_bfd,
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contents + rel->r_offset - 2)
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& 0xff00f000) == 0xe300c000
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&& bfd_get_8 (input_bfd,
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contents + rel->r_offset + 3) == 0x04)))
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contents + rel->r_offset + 3) == 0x04))
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&& (isym = bfd_sym_from_r_symndx (&htab->sym_cache,
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input_bfd, r_symndx))
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&& isym->st_shndx != SHN_ABS
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&& h != htab->elf.hdynamic
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&& h != htab->elf.hgot
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&& h != htab->elf.hplt
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&& !(isym->st_value & 1)
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&& (sym_sec = bfd_section_from_elf_index (input_bfd,
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isym->st_shndx))
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&& sym_sec->alignment_power)
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{
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unsigned short new_insn =
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(0xc000 | (bfd_get_8 (input_bfd,
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@ -1,4 +1,4 @@
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.text
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.text
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.globl foo
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foo:
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lgrl %r1,bar@GOTENT
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@ -6,6 +6,14 @@ foo:
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lrl %r1,bar@GOTENT
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l %r1,bar@GOT(%r12)
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ly %r1,bar@GOT(%r12)
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lgrl %r1,_GLOBAL_OFFSET_TABLE_@GOTENT
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lgrl %r1,misaligned_sym@GOTENT
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.data
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.globl bar
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bar: .long 0x123
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bar: .quad 0x123
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.globl misaligned_sym
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.byte 1
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misaligned_sym:
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.quad 42
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@ -1 +1 @@
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{ local: bar; };
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{ local: bar; misaligned_sym; };
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@ -4,10 +4,10 @@ tmpdir/gotreloc_31-1: file format elf32-s390
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Disassembly of section .text:
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.* <foo>:
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.*: c4 18 00 00 08 4e [ ]*lgrl %r1,118c <_GLOBAL_OFFSET_TABLE_\+0xc>
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.*: e3 10 c0 0c 00 04 [ ]*lg %r1,12\(%r12\)
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.*: c0 10 00 00 00 08 [ ]*larl %r1,10c <bar>
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.*: 58 10 c0 0c [ ]*l %r1,12\(%r12\)
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.*: c0 10 00 00 00 03 [ ]*larl %r1,10c <bar>
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.* <bar>:
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.*: 00 00 01 23 .long 0x00000123
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.*: c4 18 00 00 08 56 [ ]*lgrl %r1,11b4 <_GLOBAL_OFFSET_TABLE_\+0x14>
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.*: e3 10 c0 14 00 04 [ ]*lg %r1,20\(%r12\)
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.*: c0 10 00 00 08 52 [ ]*larl %r1,11b8 <bar>
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.*: 58 10 c0 14 [ ]*l %r1,20\(%r12\)
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.*: c0 10 00 00 08 4d [ ]*larl %r1,11b8 <bar>
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.*: c4 18 00 00 08 46 [ ]*lgrl %r1,11b0 <_GLOBAL_OFFSET_TABLE_\+0x10>
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.*: c4 18 00 00 08 41 [ ]*lgrl %r1,11ac <_GLOBAL_OFFSET_TABLE_\+0xc>
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@ -3,10 +3,10 @@ tmpdir/gotreloc_64-1: file format elf64-s390
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Disassembly of section .text:
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.* <foo>:
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.*: c0 10 00 00 00 0e [ ]*larl %r1,.* <bar>
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.*: c0 10 00 00 00 0b [ ]*larl %r1,.* <bar>
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.*: c4 1d 00 00 08 86 [ ]*lrl %r1,.* <_GLOBAL_OFFSET_TABLE_\+0x18>
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.*: 58 10 c0 18 [ ]*l %r1,24\(%r12\)
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.*: e3 10 c0 18 00 58 [ ]*ly %r1,24\(%r12\)
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.* <bar>:
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.*: 00 00 01 23 .long 0x00000123
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.*: c0 10 00 00 08 9c [ ]*larl %r1,12e8 <bar>
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.*: c0 10 00 00 08 99 [ ]*larl %r1,12e8 <bar>
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.*: c4 1d 00 00 08 92 [ ]*lrl %r1,12e0 <_GLOBAL_OFFSET_TABLE_\+0x28>
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.*: 58 10 c0 28 [ ]*l %r1,40\(%r12\)
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.*: e3 10 c0 28 00 58 [ ]*ly %r1,40\(%r12\)
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.*: c4 18 00 00 08 86 [ ]*lgrl %r1,12d8 <_GLOBAL_OFFSET_TABLE_\+0x20>
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.*: c4 18 00 00 08 7f [ ]*lgrl %r1,12d0 <_GLOBAL_OFFSET_TABLE_\+0x18>
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@ -3,10 +3,10 @@ tmpdir/gotreloc_64-1: file format elf64-s390
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Disassembly of section .text:
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.* <foo>:
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.*: c0 10 00 00 00 0e [ ]*larl %r1,.* <bar>
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.*: c0 10 00 00 00 0b [ ]*larl %r1,.* <bar>
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.*: c4 1d 00 00 0f 1a [ ]*lrl %r1,.* <_GLOBAL_OFFSET_TABLE_\+0x18>
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.*: 58 10 c0 18 [ ]*l %r1,24\(%r12\)
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.*: e3 10 c0 18 00 58 [ ]*ly %r1,24\(%r12\)
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.* <bar>:
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.*: 00 00 01 23 .long 0x00000123
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.*: c0 10 00 00 0f 0c [ ]*larl %r1,2000 <bar>
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.*: c0 10 00 00 0f 09 [ ]*larl %r1,2000 <bar>
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.*: c4 1d 00 00 0f 02 [ ]*lrl %r1,1ff8 <_GLOBAL_OFFSET_TABLE_\+0x28>
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.*: 58 10 c0 28 [ ]*l %r1,40\(%r12\)
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.*: e3 10 c0 28 00 58 [ ]*ly %r1,40\(%r12\)
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.*: c4 18 00 00 0e f6 [ ]*lgrl %r1,1ff0 <_GLOBAL_OFFSET_TABLE_\+0x20>
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.*: c4 18 00 00 0e ef [ ]*lgrl %r1,1fe8 <_GLOBAL_OFFSET_TABLE_\+0x18>
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