Since value of non-preemptible absolute symbol (SHN_ABS) won't change,
only relocations, which can be resolved as absolute value + addend, and
GOTPCREL relocations, where absolute value + addend is stored in the GOT
slot, against non-preemptible absolute symbol are allowed in PIE and
shared library.
Also convert load relocation to R_386_32, R_X86_64_32S or R_X86_64_32 for
relocation against non-preemptible absolute symbol. Don't convert to
R_X86_64_32S nor R_X86_64_32 for non-preemptible absolute symbol if they
overflow.
bfd/
PR ld/25749
PR ld/25754
* elf32-i386.c (elf_i386_convert_load_reloc): Convert load
relocation to R_386_32 for relocation against non-preemptible
absolute symbol.
(elf_i386_check_relocs): Call _bfd_elf_x86_valid_reloc_p. Don't
allocate dynamic relocation for non-preemptible absolute symbol.
(elf_i386_relocate_section): Pass sec to
GENERATE_DYNAMIC_RELOCATION_P.
* elf64-x86-64.c (R_X86_64_converted_reloc_bit): Moved.
(elf_x86_64_convert_load_reloc): Covert load relocation to
R_X86_64_32S or R_X86_64_32 for relocation against non-preemptible
absolute symbol. Don't convert to R_X86_64_32S nor R_X86_64_32
for non-preemptible absolute symbol if they overflow.
(elf_x86_64_check_relocs): Call _bfd_elf_x86_valid_reloc_p. Set
tls_type for GOT slot to GOT_ABS for non-preemptible absolute
symbol. Don't allocate dynamic relocation for non-preemptible
absolute symbol.
(elf_x86_64_relocate_section): Don't generate relative relocation
for GOTPCREL relocations aganst local absolute symbol. Pass sec
to GENERATE_DYNAMIC_RELOCATION_P.
* elfxx-x86.c (elf_x86_allocate_dynrelocs): No dynamic relocation
against non-preemptible absolute symbol.
(_bfd_elf_x86_valid_reloc_p): New function.
(_bfd_x86_elf_size_dynamic_sections): No dynamic relocation for
GOT_ABS GOT slot.
* elfxx-x86.h (GENERATE_DYNAMIC_RELOCATION_P): Add an SEC
argument. Don't generate dynamic relocation against
non-preemptible absolute symbol.
(ABS_SYMBOL_P): New.
(GENERATE_RELATIVE_RELOC_P): Don't generate relative relocation
against non-preemptible absolute symbol.
(GOT_ABS): New.
(R_X86_64_converted_reloc_bit): New. Moved from elf64-x86-64.c.
(_bfd_elf_x86_valid_reloc_p): New.
ld/
PR ld/25749
PR ld/25754
* testsuite/ld-elf/linux-x86.exp: Run ld/25749 tests.
* testsuite/ld-elf/pr25749-1.c: New file.
* testsuite/ld-elf/pr25749-1a.c: Likewise.
* testsuite/ld-elf/pr25749-1b.c: Likewise.
* testsuite/ld-elf/pr25749-1b.err: Likewise.
* testsuite/ld-elf/pr25749-1c.c: Likewise.
* testsuite/ld-elf/pr25749-1d.c: Likewise.
* testsuite/ld-elf/pr25749-2.c: Likewise.
* testsuite/ld-elf/pr25749-2a.s: Likewise.
* testsuite/ld-elf/pr25749-2b.s: Likewise.
* testsuite/ld-elf/pr25749.rd: Likewise.
* testsuite/ld-elf/pr25754-1a.c: Likewise.
* testsuite/ld-elf/pr25754-1b.s: Likewise.
* testsuite/ld-elf/pr25754-2a.c: Likewise.
* testsuite/ld-elf/pr25754-2b.err: Likewise.
* testsuite/ld-elf/pr25754-2b.s: Likewise.
* testsuite/ld-elf/pr25754-3a.c: Likewise.
* testsuite/ld-elf/pr25754-3b.s: Likewise.
* testsuite/ld-elf/pr25754-4a.c: Likewise.
* testsuite/ld-elf/pr25754-4b.s: Likewise.
* testsuite/ld-elf/pr25754-4c.s: Likewise.
* testsuite/ld-elf/pr25754-5a.c: Likewise.
* testsuite/ld-elf/pr25754-5b.s: Likewise.
* testsuite/ld-elf/pr25754-5c.s: Likewise.
* testsuite/ld-elf/pr25754-6a.c: Likewise.
* testsuite/ld-elf/pr25754-6b.s: Likewise.
* testsuite/ld-x86-64/pr19609-6a.d: Don't expect linker error.
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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) 2012-2020 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.