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96e9ba5fbb
Correct a problem with the ISA bit being stripped from the addend of compressed branch relocations, affecting RELA targets. It has been there since microMIPS support has been added, with: commit df58fc944dbc6d5efd8d3826241b64b6af22f447 Author: Richard Sandiford <rdsandiford@googlemail.com> Date: Sun Jul 24 14:20:15 2011 +0000 <https://sourceware.org/ml/binutils/2011-07/msg00198.html>, ("MIPS: microMIPS ASE support") and R_MICROMIPS_PC7_S1, R_MICROMIPS_PC10_S1 and R_MICROMIPS_PC16_S1 relocations originally affected, and the R_MIPS16_PC16_S1 relocation recently added with commit c9775dde3277 ("MIPS16: Add R_MIPS16_PC16_S1 branch relocation support") actually triggering a linker error, due to its heightened processing strictness level: $ cat test.s .text .set mips16 foo: b bar .set bar, 0x1235 .align 4, 0 $ as -EB -n32 -o test.o test.s $ objdump -dr test.o test.o: file format elf32-ntradbigmips Disassembly of section .text: 00000000 <foo>: 0: f000 1000 b 4 <foo+0x4> 0: R_MIPS16_PC16_S1 *ABS*+0x1230 ... $ ld -melf32btsmipn32 -Ttext 0 -e 0 -o test test.o test.o: In function `foo': (.text+0x0): Branch to a non-instruction-aligned address $ This is because the ISA bit of the branch target does not match the ISA bit of the referring branch, hardwired to 1 of course. Retain the ISA bit then, so that the linker knows this is really MIPS16 code referred: $ objdump -dr fixed.o fixed.o: file format elf32-ntradbigmips Disassembly of section .text: 00000000 <foo>: 0: f000 1000 b 4 <foo+0x4> 0: R_MIPS16_PC16_S1 *ABS*+0x1231 ... $ ld -melf32btsmipn32 -Ttext 0 -e 0 -o fixed fixed.o $ Add a set of MIPS16 tests to cover the relevant cases, excluding linker tests though which would overflow the in-place addend on REL targets and use them as dump patterns for RELA targets only. gas/ * config/tc-mips.c (md_apply_fix) <BFD_RELOC_MIPS16_16_PCREL_S1> <BFD_RELOC_MICROMIPS_7_PCREL_S1, BFD_RELOC_MICROMIPS_10_PCREL_S1> <BFD_RELOC_MICROMIPS_16_PCREL_S1>: Keep the ISA bit in the addend calculated. * testsuite/gas/mips/mips16-branch-absolute.s: Set the ISA bit in `bar', export `foo'. * testsuite/gas/mips/mips16-branch-absolute.d: Adjust accordingly. * testsuite/gas/mips/mips16-branch-absolute-n32.d: Likewise. * testsuite/gas/mips/mips16-branch-absolute-n64.d: Likewise. * testsuite/gas/mips/mips16-branch-absolute-addend-n32.d: Likewise. * testsuite/gas/mips/mips16-branch-absolute-addend-n64.d: Likewise. ld/ * testsuite/ld-mips-elf/mips16-branch-absolute.d: New test. * testsuite/ld-mips-elf/mips16-branch-absolute-n32.d: New test. * testsuite/ld-mips-elf/mips16-branch-absolute-n64.d: New test. * testsuite/ld-mips-elf/mips16-branch-absolute-addend.d: New test. * testsuite/ld-mips-elf/mips16-branch-absolute-addend-n32.d: New test. * testsuite/ld-mips-elf/mips16-branch-absolute-addend-n64.d: New test. * testsuite/ld-mips-elf/mips-elf.exp: Run the new tests, except from `mips16-branch-absolute' and `mips16-branch-absolute-addend', referred indirectly only.
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.texinfo), as well as the
beginnings of an internals manual (ldint.texinfo).
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.texinfo 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) 2012-2016 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.