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MIPS/BFD: Discard ineligible JALR relocations right away

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Discard R_MIPS_JALR and R_MICROMIPS_JALR relocations associated with
jumps that cannot be converted to an equivalent branch right away in
`mips_elf_calculate_relocation' rather than letting them through to
`mips_elf_perform_relocation'.  This includes cross-mode jumps which
need to flip the ISA bit or jumps to a misaligned location that cannot
be encoded with a branch, in addition to preemptible symbol references
already handled.

Cross-mode jumps are actually already rejected as the conversion is made
in `mips_elf_perform_relocation', so in this case this change only saves
some processing.  Jumps to a misaligned location are however converted,
with bits causing misalignment lost, making resulting code functionally
different even if the lone effect is avoiding an address error exception
with an instruction fetch at the jump destination requested.

Add test cases suitable, also including GAS verification to confirm that
the JALR relocations explicitly requested have indeed been output in the
intermediate objects used.

	bfd/
	* elfxx-mips.c (mips_elf_calculate_relocation) <R_MIPS_JALR>
	<R_MICROMIPS_JALR>: Discard relocation if `cross_mode_jump_p'
	or misaligned.

	gas/
	* testsuite/gas/mips/jalr4.d: New test.
	* testsuite/gas/mips/jalr4-n32.d: New test.
	* testsuite/gas/mips/jalr4-n64.d: New test.
	* testsuite/gas/mips/jalr4.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	ld/
	* testsuite/ld-mips-elf/jalr4.dd: New test.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new test.
This commit is contained in:
Maciej W. Rozycki 2017-02-23 19:26:53 +00:00
parent a567769b81
commit c1556ecd78
11 changed files with 200 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
bfd/ChangeLog
View File

@ -1,3 +1,9 @@
2017-02-23 Maciej W. Rozycki <macro@imgtec.com>
* elfxx-mips.c (mips_elf_calculate_relocation) <R_MIPS_JALR>
<R_MICROMIPS_JALR>: Discard relocation if `cross_mode_jump_p'
or misaligned.
2017-02-23 Alan Modra <amodra@gmail.com>
PR 20744

6
bfd/elfxx-mips.c
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@ -6278,7 +6278,13 @@ mips_elf_calculate_relocation (bfd *abfd, bfd *input_bfd,
when the symbol does not resolve locally. */
if (h != NULL && !SYMBOL_CALLS_LOCAL (info, &h->root))
return bfd_reloc_continue;
/* We can't optimize cross-mode jumps either. */
if (*cross_mode_jump_p)
return bfd_reloc_continue;
value = symbol + addend;
/* Neither we can non-instruction-aligned targets. */
if (r_type == R_MIPS_JALR ? (value & 3) != 0 : (value & 1) == 0)
return bfd_reloc_continue;
break;
case R_MIPS_PJUMP:

8
gas/ChangeLog
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@ -1,3 +1,11 @@
2017-02-23 Maciej W. Rozycki <macro@imgtec.com>
* testsuite/gas/mips/jalr4.d: New test.
* testsuite/gas/mips/jalr4-n32.d: New test.
* testsuite/gas/mips/jalr4-n64.d: New test.
* testsuite/gas/mips/jalr4.s: New test source.
* testsuite/gas/mips/mips.exp: Run the new tests.
2017-02-23 Sheldon Lobo <sheldon.lobo@oracle.com>
Add support for associating SPARC ASIs with an architecture level.

5
gas/testsuite/gas/mips/jalr4-n32.d Normal file
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@ -0,0 +1,5 @@
#objdump: -dr --prefix-addresses --show-raw-insn
#name: MIPS JALR reloc unaligned/cross-mode (n32)
#as: -n32
#source: jalr4.s
#dump: jalr4.d

42
gas/testsuite/gas/mips/jalr4-n64.d Normal file
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@ -0,0 +1,42 @@
#objdump: -dr --prefix-addresses --show-raw-insn
#name: MIPS JALR reloc unaligned/cross-mode (n64)
#as: -64
#source: jalr4.s
.*: +file format .*mips.*
Disassembly of section \.text:
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar0
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320000[89] jr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar0
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar1
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320000[89] jr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar1
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar2
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320000[89] jr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar2
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[ ]*[0-9a-f]+: R_MIPS_NONE \*ABS\*
[0-9a-f]+ <[^>]*> 00000000 nop
\.\.\.
\.\.\.
\.\.\.
\.\.\.

30
gas/testsuite/gas/mips/jalr4.d Normal file
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@ -0,0 +1,30 @@
#objdump: -dr --prefix-addresses --show-raw-insn
#name: MIPS JALR reloc unaligned/cross-mode (o32)
#as: -32
#source: jalr4.s
.*: +file format .*mips.*
Disassembly of section \.text:
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar0
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320000[89] jr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar0
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar1
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320000[89] jr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar1
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar2
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320000[89] jr t9
[ ]*[0-9a-f]+: R_MIPS_JALR bar2
[0-9a-f]+ <[^>]*> 00000000 nop
\.\.\.
\.\.\.
\.\.\.
\.\.\.

63
gas/testsuite/gas/mips/jalr4.s Normal file
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@ -0,0 +1,63 @@
.abicalls
.text
.align 2
.globl foo
.ent foo
foo:
.reloc 1f, R_MIPS_JALR, bar0
1: jalr $25
.reloc 1f, R_MIPS_JALR, bar0
1: jr $25
.reloc 1f, R_MIPS_JALR, bar1
1: jalr $25
.reloc 1f, R_MIPS_JALR, bar1
1: jr $25
.reloc 1f, R_MIPS_JALR, bar2
1: jalr $25
.reloc 1f, R_MIPS_JALR, bar2
1: jr $25
.end foo
# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
.align 4, 0
.space 16
.align 2
.globl bar0
.ent bar0
bar0:
.insn
.end bar0
# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
.align 4, 0
.space 16
.align 2
.globl bar1
.ent bar1
.space 2
bar1:
.insn
.end bar1
# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
.align 4, 0
.space 16
.set mips64r2
.set mips16
.align 2
.globl bar2
.ent bar2
.byte 0
bar2:
.insn
.end bar2
.set nomips16
.set mips0
# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
.align 4, 0
.space 16

8
gas/testsuite/gas/mips/mips.exp
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@ -1182,13 +1182,21 @@ if { [istarget mips*-*-vxworks*] } {
run_dump_test "jalr2"
run_dump_test_arches "jalr3" [mips_arch_list_matching mips1 \
!micromips]
run_dump_test_arches "jalr4" [mips_arch_list_matching mips1 \
!micromips]
if $has_newabi {
run_dump_test_arches "jalr3-n32" \
[mips_arch_list_matching mips3 \
!micromips]
run_dump_test_arches "jalr4-n32" \
[mips_arch_list_matching mips3 \
!micromips]
run_dump_test_arches "jalr3-n64" \
[mips_arch_list_matching mips3 \
!micromips]
run_dump_test_arches "jalr4-n64" \
[mips_arch_list_matching mips3 \
!micromips]
}
run_dump_test_arches "aent" [mips_arch_list_matching mips1]

5
ld/ChangeLog
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@ -1,3 +1,8 @@
2017-02-23 Maciej W. Rozycki <macro@imgtec.com>
* testsuite/ld-mips-elf/jalr4.dd: New test.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new test.
2017-02-23 Alan Modra <amodra@gmail.com>
PR 20744

19
ld/testsuite/ld-mips-elf/jalr4.dd Normal file
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@ -0,0 +1,19 @@
.*: +file format .*mips.*
Disassembly of section \.text:
[0-9a-f]+ <[^>]*> 0411000f bal 0+000040 <bar0>
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 1000000d b 0+000040 <bar0>
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 03200008 jr t9
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 0320f809 jalr t9
[0-9a-f]+ <[^>]*> 00000000 nop
[0-9a-f]+ <[^>]*> 03200008 jr t9
[0-9a-f]+ <[^>]*> 00000000 nop
\.\.\.
\.\.\.
\.\.\.
\.\.\.

9
ld/testsuite/ld-mips-elf/mips-elf.exp
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@ -999,7 +999,14 @@ foreach { abi } $abis {
"$abi_asflags($abi)" \
[list ../../../gas/testsuite/gas/mips/jalr3.s] \
[list "objdump -d jalr3.dd"] \
"jalr3-${abi}"]]
"jalr3-${abi}"] \
[list \
"MIPS JALR reloc unaligned/cross-mode link test ($abi)" \
"$abi_ldflags($abi) -T jalr3.ld" "" \
"$abi_asflags($abi)" \
[list ../../../gas/testsuite/gas/mips/jalr4.s] \
[list "objdump {-d --prefix-addresses --show-raw-insn} jalr4.dd"] \
"jalr4-${abi}"]]
}
proc build_mips_plt_lib { abi } {