At the cost of an extra field in the symbol table hash entries, this
simplification to the relocate_section dynamic reloc test should help
maintainability.
* elf64-ppc.c (struct ppc_link_hash_entry): Add weakref.
(ppc64_elf_copy_indirect_symbol): Set weakref. Don't merge
dyn_relocs for weakdefs.
(alias_readonly_dynrelocs): New function.
(ppc64_elf_adjust_dynamic_symbol): Use alias_readonly_dynrelocs.
(ppc64_elf_relocate_section): Simplify condition under which
dyn_relocs are emitted.
This patch fixes quite a lot of confusion in allocate_dynrelocs over
ifuncs. Function descriptors make ELFv1 quite different to ELFv2.
PR 20472
* elf64-ppc.c (ppc64_elf_before_check_relocs): Tweak abiversion test.
(readonly_dynrelocs): Comment fix.
(global_entry_stub): New function.
(ppc64_elf_adjust_dynamic_symbol): Tweak abiversion test. Match
ELFv2 code deciding on dynamic relocs vs. global entry stubs to
that in size_global_entry_stubs, handling ifunc too. Delete dead
weak sym code.
(allocate_dynrelocs): Ensure dyn_relocs field is cleared when no
dyn_relocs are needed. Correct handling of ifunc dyn_relocs.
Tidy ELIMINATE_COPY_RELOCS code, only setting dynindx for
undefweak syms. Expand and correct comments.
(size_global_entry_stubs): Ensure symbol is defined.
(ppc64_elf_relocate_section): Match condition under which
dyn_relocs are emitted to that in allocate_dynrelocs.
Undefined weak functions, like __gmon_start__, were not being made
dynamic or emitting plt call code. While the behaviour of undefined
weak symbols is not defined in the ELF standard, the intention on
powerpc64 was to make it possible to link without a definition of such
symbols and at run time behave the same as if a definition was found
at link time in a shared library.
* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Don't exit with
non_got_ref true in any case where we could have generated dynbss
copies but decide not to do so.
For the case where a function which requires an LA25 stub is at the
beginning of a section we use a short sequence comprised of a LUI/ADDIU
instruction pair only and prepended to the associated function rather
than using a trailing jump to reach the function. This works by
checking for the offset into section of the function symbol being 0.
This is however never the case for microMIPS function symbols, which
have the ISA bit set. Consequently the short LA25 sequence is never
produced for microMIPS functions, like with the following example:
$ cat la25a.s
.abicalls
.global f1
.ent f1
f1:
.set noreorder
.cpload $25
.set reorder
.option pic0
jal f2
.option pic2
jr $31
.end f1
.global f2
.ent f2
f2:
jr $31
.end f2
$ cat la25b.s
.abicalls
.option pic0
.global __start
.ent __start
__start:
jal f1
jal f2
.end __start
$ as -mmicromips -32 -EB -o la25a.o la25a.s
$ as -mmicromips -32 -EB -o la25b.o la25b.s
$ ld -melf32btsmip -o la25 la25a.o la25b.o
$ objdump -d la25
la25: file format elf32-tradbigmips
Disassembly of section .text:
004000d0 <.pic.f2>:
4000d0: 41b9 0040 lui t9,0x40
4000d4: d420 0083 j 400106 <f2>
4000d8: 3339 0107 addiu t9,t9,263
4000dc: 0000 0000 nop
004000e0 <.pic.f1>:
4000e0: 41b9 0040 lui t9,0x40
4000e4: d420 0078 j 4000f0 <f1>
4000e8: 3339 00f1 addiu t9,t9,241
4000ec: 0000 0000 nop
004000f0 <f1>:
4000f0: 41bc 0002 lui gp,0x2
4000f4: 339c 801f addiu gp,gp,-32737
4000f8: 033c e150 addu gp,gp,t9
4000fc: f420 0083 jal 400106 <f2>
400100: 0000 0000 nop
400104: 45bf jrc ra
00400106 <f2>:
400106: 45bf jrc ra
...
00400110 <__start>:
400110: f420 0070 jal 4000e0 <.pic.f1>
400114: 0000 0000 nop
400118: f420 0068 jal 4000d0 <.pic.f2>
40011c: 0000 0000 nop
$
where `.pic.f1' could omit the trailing jump and the filler NOP and just
fall through to `f1'.
Correct the problem by masking out the ISA bit from microMIPS functions,
which fixes the earlier example:
$ objdump -d la25
la25: file format elf32-tradbigmips
Disassembly of section .text:
004000d0 <.pic.f2>:
4000d0: 41b9 0040 lui t9,0x40
4000d4: d420 0083 j 400106 <f2>
4000d8: 3339 0107 addiu t9,t9,263
...
004000e8 <.pic.f1>:
4000e8: 41b9 0040 lui t9,0x40
4000ec: 3339 00f1 addiu t9,t9,241
004000f0 <f1>:
4000f0: 41bc 0002 lui gp,0x2
4000f4: 339c 801f addiu gp,gp,-32737
4000f8: 033c e150 addu gp,gp,t9
4000fc: f420 0083 jal 400106 <f2>
400100: 0000 0000 nop
400104: 45bf jrc ra
00400106 <f2>:
400106: 45bf jrc ra
...
00400110 <__start>:
400110: f420 0074 jal 4000e8 <.pic.f1>
400114: 0000 0000 nop
400118: f420 0068 jal 4000d0 <.pic.f2>
40011c: 0000 0000 nop
$
There is no need to do anything for MIPS16 functions, because if any
LA25 stub has been generated for such a function, then it is only
required for an associated call thunk only, which is regular MIPS code
and the address of which, with the ISA bit clear, is returned by
`mips_elf_get_la25_target'.
This problem has been there since the beginning of microMIPS support:
commit df58fc944d
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").
bfd/
* elfxx-mips.c (mips_elf_add_la25_stub): Clear the ISA bit of
the stub address retrieved if associated with a microMIPS
function.
Fix a problem with missing microMIPS symbol annotation with microMIPS
LA25 stub symbols. The consequence of the issue is these symbols appear
in the symbol table as regular MIPS symbols with the ISA bit set, as
shown with the example below:
$ cat la25a.s
.abicalls
.global f1
.ent f1
f1:
.set noreorder
.cpload $25
.set reorder
.option pic0
jal f2
.option pic2
jr $31
.end f1
.global f2
.ent f2
f2:
jr $31
.end f2
$ cat la25b.s
.abicalls
.option pic0
.global __start
.ent __start
__start:
jal f1
jal f2
.end __start
$ as -mmicromips -32 -EB -o la25a.o la25a.s
$ as -mmicromips -32 -EB -o la25b.o la25b.s
$ ld -melf32btsmip -o la25 la25a.o la25b.o
$ readelf -s la25
Symbol table '.symtab' contains 18 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00400098 0 SECTION LOCAL DEFAULT 1
2: 004000b0 0 SECTION LOCAL DEFAULT 2
3: 004000d0 0 SECTION LOCAL DEFAULT 3
4: 00000000 0 SECTION LOCAL DEFAULT 4
5: 00000000 0 SECTION LOCAL DEFAULT 5
6: 00418110 0 NOTYPE LOCAL DEFAULT 3 _gp
7: 004000e1 16 FUNC LOCAL DEFAULT 3 .pic.f1
8: 004000d1 16 FUNC LOCAL DEFAULT 3 .pic.f2
9: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _fdata
10: 00400110 16 FUNC GLOBAL DEFAULT [MICROMIPS] 3 __start
11: 00400106 2 FUNC GLOBAL DEFAULT [MICROMIPS] 3 f2
12: 004000d0 0 NOTYPE GLOBAL DEFAULT 3 _ftext
13: 00410120 0 NOTYPE GLOBAL DEFAULT 3 __bss_start
14: 004000f0 22 FUNC GLOBAL DEFAULT [MICROMIPS] 3 f1
15: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _edata
16: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _end
17: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _fbss
$
where microMIPS annotation is missing for `.pic.f1' and `.pic.f2' even
though these stubs are associated with microMIPS functions `f1' and `f2'
respectively.
Add the missing annotation then, by copying it from the function symbol
an LA25 stub is associated with, correcting the example above:
$ readelf -s la25
Symbol table '.symtab' contains 18 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00400098 0 SECTION LOCAL DEFAULT 1
2: 004000b0 0 SECTION LOCAL DEFAULT 2
3: 004000d0 0 SECTION LOCAL DEFAULT 3
4: 00000000 0 SECTION LOCAL DEFAULT 4
5: 00000000 0 SECTION LOCAL DEFAULT 5
6: 00418110 0 NOTYPE LOCAL DEFAULT 3 _gp
7: 004000e0 16 FUNC LOCAL DEFAULT [MICROMIPS] 3 .pic.f1
8: 004000d0 16 FUNC LOCAL DEFAULT [MICROMIPS] 3 .pic.f2
9: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _fdata
10: 00400110 16 FUNC GLOBAL DEFAULT [MICROMIPS] 3 __start
11: 00400106 2 FUNC GLOBAL DEFAULT [MICROMIPS] 3 f2
12: 004000d0 0 NOTYPE GLOBAL DEFAULT 3 _ftext
13: 00410120 0 NOTYPE GLOBAL DEFAULT 3 __bss_start
14: 004000f0 22 FUNC GLOBAL DEFAULT [MICROMIPS] 3 f1
15: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _edata
16: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _end
17: 00410120 0 NOTYPE GLOBAL DEFAULT 3 _fbss
$
This problem has been there since the beginning of microMIPS support:
commit df58fc944d
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").
bfd/
* elfxx-mips.c (mips_elf_create_stub_symbol): For a microMIPS
stub also add STO_MICROMIPS annotation.
Fix a linker regression introduced with commit 9d862524f6 ("MIPS:
Verify the ISA mode and alignment of branch and jump targets") causing a
build failure in microMIPS glibc where the `zdump' tool fails to link:
.../timezone/zdump.o: In function `yeartot':
.../timezone/zdump.c:758:(.text+0x62): Jump to a non-instruction-aligned address
.../timezone/zdump.c:758:(.text+0x76): Jump to a non-instruction-aligned address
.../timezone/zdump.c:768:(.text+0x112): Jump to a non-instruction-aligned address
.../timezone/zdump.c:774:(.text+0x1b8): Jump to a non-instruction-aligned address
.../timezone/zdump.c:774:(.text+0x1cc): Jump to a non-instruction-aligned address
collect2: error: ld returned 1 exit status
make[2]: *** [.../timezone/zdump] Error 1
The cause of the failure is the stricter check introduced with the said
change for jump and branch targets tripping on the address of microMIPS
LA25 stubs. Despite being microMIPS code these stubs do not have the
ISA bit set throughout the relocation calculation process, because they
have their address set to the memory offset into the stub section they
are placed in.
The `mips_elf_la25_stub' structure does not carry ISA mode information,
but there is no need to extend it, because the ISA mode can be inferred
from the original symbol, which will have STO_MICROMIPS annotation, so
use that instead to set the ISA bit appropriately. Also only LA25 stubs
associated with microMIPS symbols need to have the ISA bit set, because
other LA25 stubs are made with regular MIPS code, even if associated
with a MIPS16 symbol (in which case they are needed by a call thunk only
rather than the MIPS16 function proper).
bfd/
* elfxx-mips.c (mips_elf_calculate_relocation): Set the ISA bit
in microMIPS LA25 stub references.
* doc/chew.c (delete_string): Only free the string buffer if it is
there. Mark the buffer as NULL after freeing.
(drop): Free the dropped string.
(free_words): New function: Frees the memory allocated to the
dictionary.
(add_instrinsic): Duplicate the name string, so that it can be
freed later on.
(compile): Free unused words.
(main): Free the dictionary and top level string buffers at the
end.
bfd/
* elf32-arm.c (CMSE_PREFIX): Define macro.
(elf32_arm_stub_cmse_branch_thumb_only): Define stub sequence.
(cmse_branch_thumb_only): Declare stub.
(struct elf32_arm_link_hash_table): Define cmse_stub_sec field.
(elf32_arm_get_plt_info): Add globals parameter. Use it to return
FALSE if there is no PLT.
(arm_type_of_stub): Adapt to new elf32_arm_get_plt_info signature.
(elf32_arm_final_link_relocate): Likewise.
(elf32_arm_gc_sweep_hook): Likewise.
(elf32_arm_gc_mark_extra_sections): Mark sections holding ARMv8-M
secure entry functions.
(arm_stub_is_thumb): Add case for arm_stub_cmse_branch_thumb_only.
(arm_dedicated_stub_output_section_required): Change to a switch case
and add a case for arm_stub_cmse_branch_thumb_only.
(arm_dedicated_stub_output_section_required_alignment): Likewise.
(arm_stub_dedicated_output_section_name): Likewise.
(arm_stub_dedicated_input_section_ptr): Likewise and remove
ATTRIBUTE_UNUSED for htab parameter.
(arm_stub_required_alignment): Likewise.
(arm_stub_sym_claimed): Likewise.
(arm_dedicated_stub_section_padding): Likewise.
(cmse_scan): New function.
(elf32_arm_size_stubs): Call cmse_scan for ARM M profile targets.
Set stub_changed to TRUE if such veneers were created.
(elf32_arm_swap_symbol_in): Add detection code for CMSE special
symbols.
include/
* arm.h (ARM_GET_SYM_CMSE_SPCL): Define macro.
(ARM_SET_SYM_CMSE_SPCL): Likewise.
ld/
* ld.texinfo (Placement of SG veneers): New concept entry.
* testsuite/ld-arm/arm-elf.exp
(Secure gateway veneers: no .gnu.sgstubs section): New test.
(Secure gateway veneers: wrong entry functions): Likewise.
(Secure gateway veneers (ARMv8-M Baseline)): Likewise.
(Secure gateway veneers (ARMv8-M Mainline)): Likewise.
* testsuite/ld-arm/cmse-veneers.s: New file.
* testsuite/ld-arm/cmse-veneers.d: Likewise.
* testsuite/ld-arm/cmse-veneers.rd: Likewise.
* testsuite/ld-arm/cmse-veneers.sd: Likewise.
* testsuite/ld-arm/cmse-veneers-no-gnu_sgstubs.out: Likewise.
* testsuite/ld-arm/cmse-veneers-wrong-entryfct.out: Likewise.
Complement:
commit 1bbce13264
Author: Maciej W. Rozycki <macro@linux-mips.org>
Date: Mon Jun 24 23:55:46 2013 +0000
<https://sourceware.org/ml/binutils/2013-06/msg00077.html>, ("MIPS:
Compressed PLT/stubs support"), and also choose between regular and
compressed PLT entries as appropriate for any branches referring.
bfd/
* elfxx-mips.c (mips_elf_calculate_relocation): Handle branches
in PLT compression selection.
(_bfd_mips_elf_check_relocs): Likewise.
ld/
* testsuite/ld-mips-elf/compressed-plt-1.s: Add branch support.
* testsuite/ld-mips-elf/compressed-plt-1a.s: Likewise.
* testsuite/ld-mips-elf/compressed-plt-1b.s: Likewise.
* testsuite/ld-mips-elf/compressed-plt-1-o32-branch.od: New
test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-branch.rd: New
test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-mips16-bronly.od:
New test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-mips16-bronly.rd:
New test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-mips16-branch.od:
New test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-mips16-branch.rd:
New test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-umips-bronly.od:
New test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-umips-bronly.rd:
New test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-umips-branch.od:
New test.
* testsuite/ld-mips-elf/compressed-plt-1-o32-umips-branch.rd:
New test.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
bfd * arc-got.h (relocate_fix_got_relocs_for_got_info): Handle the case
where there's no elf_link_hash_entry while processing GOT_NORMAL got
entries.
ld * testsuite/ld-arc/got-01.d: New file.
* testsuite/ld-arc/got-01.s: New file.
