binutils-gdb/ld/emulparams/dt-relr.sh
H.J. Lu 6a91be8666 ld: Initial DT_RELR support
Add a -z pack-relative-relocs option to enable DT_RELR and create a
relr.dyn section for DT_RELR.  DT_RELR is implemented with the linker
relaxation infrastructure, but it doesn't require the --relax option
enabled.  -z pack-relative-relocs implies -z combreloc.  -z nocombreloc
implies -z nopack-relative-relocs.

-z pack-relative-relocs is chosen over the similar option in lld,
--pack-dyn-relocs=relr, to implement a glibc binary lockout mechanism
with a special glibc version symbol, to avoid random crashes of DT_RELR
binaries with the existing glibc binaries.

bfd/

	* elf-bfd.h (elf_link_hash_table): Add srelrdyn.
	* elflink.c (_bfd_elf_link_create_dynamic_sections): Create a
	.relr.dyn section for DT_RELR.

include/

	* bfdlink.h (bfd_link_info): Add enable_dt_relr.

ld/

	* News: Mention -z pack-relative-relocs and
	-z nopack-relative-relocs.
	* ld.texi: Document -z pack-relative-relocs and
	-z nopack-relative-relocs.
	* ldelf.c (ldelf_after_parse): Disable DT_RELR if not building
	PIE nor shared library.  Add 3 spare dynamic tags for DT_RELR,
	DT_RELRSZ and DT_RELRENT.
	* ldlang.c (lang_relax_sections): Also enable relaxation if
	DT_RELR is enabled.
	* emulparams/elf32_x86_64.sh: Source dt-relr.sh.
	* emulparams/elf_i386.sh: Likewise.
	* emulparams/elf_x86_64.sh: Likewise.
	* emulparams/dt-relr.sh: New file.
	* scripttempl/elf.sc: Support .relr.dyn.
2022-01-12 06:04:29 -08:00

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HAVE_DT_RELR=yes
PARSE_AND_LIST_OPTIONS_PACK_RELATIVE_RELOCS='
fprintf (file, _("\
-z pack-relative-relocs Pack relative relocations\n"));
fprintf (file, _("\
-z nopack-relative-relocs Do not pack relative relocations (default)\n"));
'
PARSE_AND_LIST_ARGS_CASE_Z_PACK_RELATIVE_RELOCS='
else if (strcmp (optarg, "pack-relative-relocs") == 0)
link_info.enable_dt_relr = true;
else if (strcmp (optarg, "nopack-relative-relocs") == 0)
link_info.enable_dt_relr = false;
'
PARSE_AND_LIST_OPTIONS="$PARSE_AND_LIST_OPTIONS $PARSE_AND_LIST_OPTIONS_PACK_RELATIVE_RELOCS"
PARSE_AND_LIST_ARGS_CASE_Z="$PARSE_AND_LIST_ARGS_CASE_Z $PARSE_AND_LIST_ARGS_CASE_Z_PACK_RELATIVE_RELOCS"