Assume next code (1.s):
./as-new 1.s -o out
readelf -a out
[ 5] .text PROGBITS 0000000000000000 00000048
0000000000000008 0000000000000000 AXG 0 0 1
[ 6] .rela.text RELA 0000000000000000 00000120
0000000000000018 0000000000000018 I 7 5 8
As shown, .rela.text is present for .text, it has 5 as sh_info field, but gas does not include it into group:
COMDAT group section [ 1] `.group' [foo] contains 1 sections:
[ 5] .text
During the "regular" part of the link, the linker includes or discards groups as a unit.
ELF spec that says: "There may *not* be non-symbol references to the sections comprising a group from outside the group, for example, use of a group member's section header index in an sh_link or sh_info member."
So it looks to be violation of spec.
The master branch has been updated by Alan Modra <email@example.com>:
Author: Alan Modra <firstname.lastname@example.org>
Date: Wed Oct 4 09:53:53 2017 +1030
PR21167, relocation sections not included in groups
This fixes a wart I've known about for years, but haven't done
anything about because BFD treats relocation sections as an adjunct to
the section they relocate. SHF_GROUP on the section thus implicitly
applies to its relocation section(s), but it is an error that the
reloc sections aren't part of the group.
Like many patches to gas, this wasn't as straightforward as it could
be due to a number of backends, i386, cr16 and others, removing relocs
in tc_get_reloc rather than marking them as "done" earlier in
md_apply_reloc. So it isn't possible for the group support to
reliably detect the presence of relocs by looking at fixups earlier
than write_relocs. However the group support needs to create
signature symbols, and that must be done before the symbol table is
frozen, before write_relocs. So split off the group sizing from
elf_adjust_symtab and put it in elf_frob_file_after_relocs.
* elf.c (_bfd_elf_setup_sections): Don't trim reloc sections from
(_bfd_elf_init_reloc_shdr): Pass sec_hdr, use it to copy SHF_GROUP
flag from section.
(elf_fake_sections): Adjust calls. Exit immediately on failure.
(bfd_elf_set_group_contents): Add associated reloc section indices
to group contents
* config/obj-elf.c (struct group_list): Delete elt_count.
(groups): New static.
(build_group_lists): Don't count elements.
(elf_adjust_symtab): Use groups rather than auto list. Set up
pointer from group member to SHT_GROUP section. Don't size
SHT_GROUP section or clean up here..
(elf_frob_file_after_relocs): ..do so here instead.
* testsuite/gas/mips/compact-eh-el-5.d: Adjust.
* testsuite/ld-elf/group9b.d: Adjust for relocs included in group.
Fixed master, and in my opinion the risk/benefit makes this patch not suitable for backporting to 2.29.
The master branch has been updated by H.J. Lu <email@example.com>:
Author: H.J. Lu <firstname.lastname@example.org>
Date: Wed Oct 4 18:01:47 2017 -0700
Add an assembler test for PR gas/21167
* testsuite/gas/elf/elf.exp: Run group3.
* testsuite/gas/elf/group3.d: New file.
* testsuite/gas/elf/group3.s: Likewise.