This patch adds support for the R_386_GOT32X relocation proposed in
https://groups.google.com/forum/#!topic/ia32-abi/GbJJskkid4I
to gas and ld. It updates gas to generate R_386_GOT32X relocation for
memory operand, foo@GOT[(%reg)]. We must encode "mov foo@GOT, %eax"
with the 0x8b opcode, instead of the 0xb8 opcode, so that it can be
transformed to "lea foo, %eax". With the locally defined symbol, foo,
we convert
mov foo@GOT[(%reg1)], %reg2
to
lea foo[@GOTOFF(%reg1)], %reg2
and convert
call/jmp *foo@GOT[(%reg)]
to
nop call foo/jmp foo nop
When PIC is false, convert
test %reg1, foo@GOT[(%reg2)]
to
test $foo, %reg1
and convert
binop foo@GOT[(%reg1)], %reg2
to
binop $foo, %reg2
where binop is one of adc, add, and, cmp, or, sbb, sub, xor instructions.
bfd/
* elf32-i386.c: Include opcode/i386.h.
(elf_howto_table): Add R_386_GOT32X.
(R_386_ext2): Replace R_386_IRELATIVE with R_386_GOT32X.
(elf_i386_reloc_type_lookup): Handle BFD_RELOC_386_GOT32X.
(need_convert_mov_to_lea): Renamed to ...
(need_convert_load): This.
(elf_i386_check_relocs): Handle R_386_GOT32X. Replace
need_convert_mov_to_lea with need_convert_load.
(elf_i386_gc_sweep_hook): Handle R_386_GOT32X.
(elf_i386_size_dynamic_sections): Likewise.
(elf_i386_relocate_section): Likewise.
(elf_i386_convert_mov_to_lea): Renamed to ...
(elf_i386_convert_load): This. Replace need_convert_mov_to_lea
with need_convert_load. Support R_386_GOT32X transformations.
* reloc.c (BFD_RELOC_386_GOT32X): New.
* bfd-in2.h: Regenerated.
* libbfd.h: Likewise.
gas/
* config/tc-i386.c (tc_i386_fix_adjustable): Handle
BFD_RELOC_386_GOT32X.
(tc_gen_reloc): Likewise.
(match_template): Force 0x8b encoding for "mov foo@GOT, %eax".
(output_disp): Check for "call/jmp *mem", "mov mem, %reg",
"test %reg, mem" and "binop mem, %reg" where binop is one of
adc, add, and, cmp, or, sbb, sub, xor instructions. Set
fx_tcbit if the REX prefix is generated. Set fx_tcbit2 if
BFD_RELOC_386_GOT32X should be generated.
(i386_validate_fix): Generate BFD_RELOC_386_GOT32X if fx_tcbit2
is set.
gas/testsuite/
* gas/i386/got.d: New file.
* gas/i386/got.s: Likewise.
* gas/i386/i386.exp: Run got.
* gas/i386/localpic.d: Replace R_386_GOT32 with R_386_GOT32X.
* gas/i386/mixed-mode-reloc32.d: Likewise.
* gas/i386/reloc32.d: Likewise.
include/elf/
* i386.h (R_386_GOT32X): New relocation.
ld/testsuite/
* ld-i386/branch1.d: New file.
* ld-i386/branch1.s: Likewise.
* ld-i386/call1.d: Likewise.
* ld-i386/call1.s: Likewise.
* ld-i386/call2.d: Likewise.
* ld-i386/call2.s: Likewise.
* ld-i386/got1.dd: Likewise.
* ld-i386/got1.out: Likewise.
* ld-i386/got1a.S: Likewise.
* ld-i386/got1b.c: Likewise.
* ld-i386/got1c.c: Likewise.
* ld-i386/got1d.S: Likewise.
* ld-i386/jmp1.d: Likewise.
* ld-i386/jmp1.s: Likewise.
* ld-i386/jmp2.d: Likewise.
* ld-i386/jmp2.s: Likewise.
* ld-i386/load1.d: Likewise.
* ld-i386/load1.s: Likewise.
* ld-i386/load2.d: Likewise.
* ld-i386/load2.s: Likewise.
* ld-i386/load3.d: Likewise.
* ld-i386/load3.s: Likewise.
* ld-i386/load4.s: Likewise.
* ld-i386/load4a.d: Likewise.
* ld-i386/load4b.d: Likewise.
* ld-i386/load5.s: Likewise.
* ld-i386/load5a.d: Likewise.
* ld-i386/load5b.d: Likewise.
* ld-i386/load6.d: Likewise.
* ld-i386/load6.s: Likewise.
* ld-i386/i386.exp: Run branch1, call1, call2, jmp1, jmp2,
load1, load2, load3, load4a, load4b, load5a, load5b and load6
tests. Run got1 test.
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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.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.
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Copying and distribution of this file, with or without modification,
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