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On Linux/x86, programs and shared libraries compiled with -mtls-dialect=gnu2 may fail silently at run-time against glibc without the GNU2 TLS run-time fixes for: https://sourceware.org/bugzilla/show_bug.cgi?id=31501 https://sourceware.org/bugzilla/show_bug.cgi?id=31372 A version tag, GLIBC_ABI_GNU2_TLS, has been added to glibc to indicate that glibc has the working GNU2 TLS run-time. Add the --gnu2-tls-tag option to i386/x86-64 ELF linker to add the GLIBC_ABI_GNU2_TLS version dependency in output programs and shared libraries when linking against glibc if input relocatable object files have R_386_TLS_DESC_CALL or R_X86_64_TLSDESC_CALL relocation. The output will fail to load and run at run-time against glibc which doesn't define the GLIBC_ABI_GNU2_TLS version. Add the --enable-gnu2-tls-tag configure option to enable --gnu2-tls-tag by default. If unspecified, linker will add the GLIBC_ABI_GNU2_TLS version dependency if input object files have R_386_TLS_DESC_CALL or R_X86_64_TLSDESC_CALL relocation and libc.so defines the GLIBC_ABI_GNU2_TLS version. Update elf_link_add_glibc_verneed to properly add the GLIBC_2.36 version dependency when -z mark-plt -z nopack-relative-relocs passed to x86-64 ELF linker. bfd/ PR ld/33130 * elf-bfd.h (_bfd_elf_link_add_glibc_version_dependency): Add a pointer to bool argument. * elf-linker-x86.h (elf_linker_x86_params): Add gnu2_tls_version_tag. * elf32-i386.c (elf_i386_scan_relocs): Set has_tls_desc_call to 1 for R_386_TLS_DESC_CALL. (elf_i386_add_glibc_version_dependency): New. Undef before FreeBSD support. * elf64-x86-64.c (elf_x86_64_scan_relocs): Set has_tls_desc_call to 1 for R_X86_64_TLSDESC_CALL. (elf_x86_64_add_glibc_version_dependency): Add GLIBC_ABI_GNU2_TLS version dependency if GLIBC_ABI_GNU2_TLS dependency isn't disabled and has_tlsdesc_call isn't 0. (elf_backend_add_glibc_version_dependency): Undef before FreeBSD support and redefine for elf32-x86-64. * elflink.c (elf_link_add_glibc_verneed): Changed to return bool. Remove the pointer to elf_find_verdep_info argument. Add a pointer to bool argument, auto_version. Return true if linked against glibc. Otherwise return false. If the version dependency is added, set *auto_version to true. If *auto_version is true, add the version dependency only if libc.so defines the version. (_bfd_elf_link_add_glibc_version_dependency): Add a pointer to bool argument and pass it to elf_link_add_glibc_verneed. (_bfd_elf_link_add_dt_relr_dependency): Pass NULL to _bfd_elf_link_add_glibc_version_dependency. * elfxx-x86.h (elf_x86_link_hash_table): Add has_tls_desc_call. ld/ PR ld/33130 * NEWS: Mention --gnu2-tls-tag, --no-gnu2-tls-tag and --enable-gnu2-tls-tag. * config.in: Regenerated. * configure: Likewise. * configure.ac: Add --enable-gnu2-tls-tag. * ld.texi: Document --gnu2-tls-tag/--no-gnu2-tls-tag. * ldlex.h (option_values): Add OPTION_GNU2_TLS_VERSION_TAG and OPTION_NO_GNU2_TLS_VERSION_TAG. * emulparams/elf32_x86_64.sh (EXTRA_EM_FILE): Changed to "elf-x86-64-glibc". * emulparams/elf_i386.sh (EXTRA_EM_FILE): Set to "elf-i386-glibc". * emulparams/elf_i386_fbsd.sh (EXTRA_EM_FILE): New. Set to "elf-x86". * emulparams/elf_i386_haiku.sh (EXTRA_EM_FILE): Likewise. * emulparams/elf_x86_64.sh (EXTRA_EM_FILE): Likewise. * emulparams/elf_x86_64_fbsd.sh (EXTRA_EM_FILE): New. Set to "elf-x86-64". * emulparams/elf_x86_64_haiku.sh (EXTRA_EM_FILE): Likewise. * (EXTRA_EM_FILE): Likewise. * (EXTRA_EM_FILE): Likewise. * emultempl/elf-i386-glibc.em: New file. * emultempl/elf-x86-64-glibc.em: Likewise. * emultempl/elf-x86-64.em: Likewise. * emultempl/elf-x86-glibc.em: Likewise. * emultempl/elf-x86.em (elf_x86_64_before_parse): Removed. (LDEMUL_BEFORE_PARSE): Likewise. (elf_x86_64_before_allocation): Likewise. (LDEMUL_BEFORE_ALLOCATION): Likewise. * emultempl/solaris2-x86-64.em: New file. * testsuite/ld-i386/gnu2-tls-1.s: Likewise. * testsuite/ld-i386/gnu2-tls-1a.rd: Likewise. * testsuite/ld-i386/gnu2-tls-1b.rd: Likewise. * testsuite/ld-x86-64/gnu2-tls-1.s: Likewise. * testsuite/ld-x86-64/gnu2-tls-1a.rd: Likewise. * testsuite/ld-x86-64/gnu2-tls-1b.rd: Likewise. * testsuite/ld-x86-64/mark-plt-2.rd: Likewise. * testsuite/ld-x86-64/mark-plt-2.s: Likewise. * testsuite/ld-i386/i386.exp: Run GLIBC_ABI_GNU2_TLS tests. * testsuite/ld-x86-64/x86-64.exp: Likewise. Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
README for LD
This is the GNU linker. It is distributed with other "binary
utilities" which should be in ../binutils. See ../binutils/README for
more general notes, including where to send bug reports.
There are many features of the linker:
* The linker uses a Binary File Descriptor library (../bfd)
that it uses to read and write object files. This helps
insulate the linker itself from the format of object files.
* The linker supports a number of different object file
formats. It can even handle multiple formats at once:
Read two input formats and write a third.
* The linker can be configured for cross-linking.
* The linker supports a control language.
* There is a user manual (ld.texi), as well as the
beginnings of an internals manual (ldint.texi).
Installation
============
See ../binutils/README.
If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.
To build just the linker, make the target all-ld from the top level
directory (one directory above this one).
Porting to a new target
=======================
See the ldint.texi manual.
Reporting bugs etc
===========================
See ../binutils/README.
Known problems
==============
The Solaris linker normally exports all dynamic symbols from an
executable. The GNU linker does not do this by default. This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets). This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl. You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.
HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly. The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages. There are various
workarounds to this:
* Build and install bash, and build with "make SHELL=bash".
* Update to a version of HP/UX with a working shell (e.g., 9.05).
* Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
emulparams script used exports any shell variables it sets.
Copyright (C) 2012-2025 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.