It is possible to create shared libraries on PowerPC using
-ftls-model=inital-exec or -ftls-model=local-exec. The first is half
reasonable, getting you a shared library that can't be dlopen'd but
otherwise is reasonable. The second is quite bad. Not only do you
lose being able to dlopen, the library also has dynamic text
relocations. Worse, the TPREL16_LO, TPREL16_HA and other TPREL16
dynamic relocs emitted were wrong, resulting in wrong values being
applied by ld.so.
Using the first TLS section symbol in dynamic relocations for local
TLS symbols doesn't work. It's wrong because TLS symbols used by TLS
relocs have values relative to the TLS segment, whereas the TLS
section symbols are addresses. This patch instead uses a symbol index
of zero which is used elsewhere by PowerPC on dynamic TLS relocs.
It's not strictly ABI compliant to use a non-TLS symbol with TLS
relocs but symbol index zero can be interpreted as "no symbol". Not
using the first TLS section symbol means it doesn't need to be dynamic.
The patch also fixes a further problem with PowerPC32 dynamic TPREL16*
relocs, which shouldn't have the symbol value in the addend as we do
for non-TLS symbols.
bfd/
* elflink.c (_bfd_elf_omit_section_dynsym_default): Don't keep
tls_sec.
(_bfd_elf_init_1_index_section): Prefer not using TLS sections.
(_bfd_elf_init_2_index_sections): Likewise.
* elf64-ppc.c (ppc64_elf_relocate_section): When emitting dynamic
relocations for local TLS symbols, use STN_UNDEF as the relocation
symbol.
* elf32-ppc.c (ppc_elf_relocate_section): Likewise, and don't
leave TLS symbol value in the addend.
ld/
* testsuite/ld-powerpc/tlsso.r: Update.
* testsuite/ld-powerpc/tlsso32.g: Update.
* testsuite/ld-powerpc/tlsso32.r: Update.
* testsuite/ld-powerpc/tlstocso.r: Update.
* testsuite/ld-cris/tls-dso-dtpoffd2.d: Update.
* testsuite/ld-cris/tls-dso-dtpoffd4.d: Update.
* testsuite/ld-cris/tls-dso-tpoffgotcomm1.d: Update.
* testsuite/ld-cris/tls-gd-1.d: Update.
* testsuite/ld-cris/tls-gd-1h.d: Update.
* testsuite/ld-cris/tls-gd-2.d: Update.
* testsuite/ld-cris/tls-gd-2h.d: Update.
* testsuite/ld-cris/tls-ie-10.d: Update.
* testsuite/ld-cris/tls-ie-11.d: Update.
* testsuite/ld-cris/tls-ie-8.d: Update.
* testsuite/ld-cris/tls-ie-9.d: Update.
* testsuite/ld-cris/tls-js1.d: Update.
* testsuite/ld-cris/tls-ld-4.d: Update.
* testsuite/ld-cris/tls-ld-5.d: Update.
* testsuite/ld-cris/tls-ld-6.d: Update.
* testsuite/ld-cris/tls-ld-7.d: Update.
* testsuite/ld-cris/tls-ldgd-14.d: Update.
* testsuite/ld-cris/tls-ldgd-15.d: Update.
* testsuite/ld-cris/tls-ldgdx-14.d: Update.
* testsuite/ld-cris/tls-ldgdx-15.d: Update.
* testsuite/ld-cris/tls-local-54.d: Update.
* testsuite/ld-cris/tls-local-60.d: Update.
* testsuite/ld-cris/tls-local-61.d: Update.
* testsuite/ld-cris/tls-local-63.d: Update.
* testsuite/ld-cris/tls-local-64.d: Update.
* testsuite/ld-cris/tls-ok-30.d: Update.
* testsuite/ld-cris/tls-ok-32.d: Update.
* testsuite/ld-cris/tls-ok-34.d: Update.
* testsuite/ld-mips-elf/tls-multi-got-1.got: Update.
* testsuite/ld-mips-elf/tls-multi-got-1.r: Update.
* testsuite/ld-mips-elf/tlsdyn-pie-o32.d: Update.
* testsuite/ld-mips-elf/tlsdyn-pie-o32.got: Update.
* testsuite/ld-mips-elf/tlslib-o32-hidden.got: Update.
* testsuite/ld-mips-elf/tlslib-o32-ver.got: Update.
* testsuite/ld-mips-elf/tlslib-o32.got: Update.
* testsuite/ld-s390/tlspic.rd: Update.
* testsuite/ld-s390/tlspic_64.rd: Update.
* testsuite/ld-sparc/tlssunnopic32.rd: Update.
* testsuite/ld-sparc/tlssunnopic64.rd: Update.
* testsuite/ld-sparc/tlssunpic32.rd: Update.
* testsuite/ld-sparc/tlssunpic64.rd: Update.
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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) 2012-2019 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.