mirrors/binutils-gdb
1
0
Fork 0
mirror of https://sourceware.org/git/binutils-gdb.git synced 2024-11-24 10:35:12 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

[PATCH v3] aarch64: Emit jump slot for conditional branch to undefined symbols

Browse Source 
The linker silently writes out a conditional branch to 0 if the
target symbol in R_AARCH64_CONDBR19 or R_AARCH64_TSTBR14 relocations is
undefined.  Emit a PLT instead so that behaviour is the same for these
relocations as the llvm linker.

The special behaviour for undefined weak symbols, where conditional
branches to such symbols result in a branch unto themselves, has been
retained.  This is because the weak-undefined.s test explicitly checks
for that, leading me to conclude that it's expected behaviour.

bfd	* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Club
	BFD_RELOC_AARCH64_BRANCH19 and BFD_RELOC_AARCH64_TSTBR14
	cases with BFD_RELOC_AARCH64_JUMP26.
	(elfNN_aarch64_check_relocs): Likewise.

ld	* testsuite/ld-aarch64/aarch64-elf.exp: New test
	emit-relocs-560.
	* testsuite/ld-aarch64/emit-relocs-560.d: New file.
	* testsuite/ld-aarch64/emit-relocs-560.s: New file.
This commit is contained in:
Siddhesh Poyarekar 2020-05-19 11:07:52 +01:00 committed by Nick Clifton
parent 607b483327
commit 7e05773767
6 changed files with 44 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
bfd/ChangeLog
View File

@ -1,3 +1,10 @@
2020-05-19 Siddhesh Poyarekar <siddesh.poyarekar@arm.com>
* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Club
BFD_RELOC_AARCH64_BRANCH19 and BFD_RELOC_AARCH64_TSTBR14
cases with BFD_RELOC_AARCH64_JUMP26.
(elfNN_aarch64_check_relocs): Likewise.
2020-05-19 Alan Modra <amodra@gmail.com>
* aix5ppc-core.c (xcoff64_core_file_matches_executable_p): Use

22
bfd/elfnn-aarch64.c
View File

@ -5494,6 +5494,7 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
bfd_vma orig_value = value;
bfd_boolean resolved_to_zero;
bfd_boolean abs_symbol_p;
bfd_boolean via_plt_p;
globals = elf_aarch64_hash_table (info);
@ -5515,6 +5516,8 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
: bfd_is_und_section (sym_sec));
abs_symbol_p = h != NULL && bfd_is_abs_symbol (&h->root);
via_plt_p = (globals->root.splt != NULL && h != NULL
&& h->plt.offset != (bfd_vma) - 1);
/* Since STT_GNU_IFUNC symbol must go through PLT, we handle
it here if it is defined in a non-shared object. */
@ -5850,12 +5853,23 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
value += signed_addend;
break;
case BFD_RELOC_AARCH64_BRANCH19:
case BFD_RELOC_AARCH64_TSTBR14:
/* A conditional branch to an undefined weak symbol is converted to a
branch to itself. */
if (weak_undef_p && !via_plt_p)
{
value = _bfd_aarch64_elf_resolve_relocation (input_bfd, bfd_r_type,
place, value,
signed_addend,
weak_undef_p);
break;
}
/* Fall through. */
case BFD_RELOC_AARCH64_CALL26:
case BFD_RELOC_AARCH64_JUMP26:
{
asection *splt = globals->root.splt;
bfd_boolean via_plt_p =
splt != NULL && h != NULL && h->plt.offset != (bfd_vma) - 1;
/* A call to an undefined weak symbol is converted to a jump to
the next instruction unless a PLT entry will be created.
@ -5943,7 +5957,6 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
case BFD_RELOC_AARCH64_32:
#endif
case BFD_RELOC_AARCH64_ADD_LO12:
case BFD_RELOC_AARCH64_BRANCH19:
case BFD_RELOC_AARCH64_LDST128_LO12:
case BFD_RELOC_AARCH64_LDST16_LO12:
case BFD_RELOC_AARCH64_LDST32_LO12:
@ -5959,7 +5972,6 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
case BFD_RELOC_AARCH64_MOVW_G2_NC:
case BFD_RELOC_AARCH64_MOVW_G2_S:
case BFD_RELOC_AARCH64_MOVW_G3:
case BFD_RELOC_AARCH64_TSTBR14:
value = _bfd_aarch64_elf_resolve_relocation (input_bfd, bfd_r_type,
place, value,
signed_addend, weak_undef_p);
@ -8022,6 +8034,8 @@ elfNN_aarch64_check_relocs (bfd *abfd, struct bfd_link_info *info,
break;
}
case BFD_RELOC_AARCH64_BRANCH19:
case BFD_RELOC_AARCH64_TSTBR14:
case BFD_RELOC_AARCH64_CALL26:
case BFD_RELOC_AARCH64_JUMP26:
/* If this is a local symbol then we resolve it

7
ld/ChangeLog
View File

@ -1,3 +1,10 @@
2020-05-19 Siddhesh Poyarekar <siddesh.poyarekar@arm.com>
* testsuite/ld-aarch64/aarch64-elf.exp: New test
emit-relocs-560.
* testsuite/ld-aarch64/emit-relocs-560.d: New file.
* testsuite/ld-aarch64/emit-relocs-560.s: New file.
2020-05-19 Alan Modra <amodra@gmail.com>
* emultempl/beos.em (sort_by_file_name): Use bfd_get_filename

1
ld/testsuite/ld-aarch64/aarch64-elf.exp
View File

@ -236,6 +236,7 @@ run_dump_test_lp64 "emit-relocs-557"
run_dump_test_lp64 "emit-relocs-558"
run_dump_test_lp64 "emit-relocs-558-overflow"
run_dump_test_lp64 "emit-relocs-559"
run_dump_test_lp64 "emit-relocs-560"
run_dump_test "reloc-overflow-bad"

8
ld/testsuite/ld-aarch64/emit-relocs-560.d Normal file
View File

@ -0,0 +1,8 @@
#source: emit-relocs-560.s
#ld: -shared
#readelf: -r
Relocation section '.rela.plt' at offset 0x[0-9a-f]+ contains 2 entries:
Offset Info Type Sym. Value Sym. Name \+ Addend
[0-9a-f]+ 000100000402 R_AARCH64_JUMP_SL 0000000000000000 baz \+ 0
[0-9a-f]+ 000200000402 R_AARCH64_JUMP_SL 0000000000000000 bar \+ 0

3
ld/testsuite/ld-aarch64/emit-relocs-560.s Normal file
View File

@ -0,0 +1,3 @@
foo:
tbz x0, 1, bar
cbnz x1, baz