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aarch64: Return an error on conditional branch to an undefined symbol

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The fix in 7e05773767 introduced a PLT
for conditional jumps when the target symbol is undefined.  This is
incorrect because conditional branch relocations are not allowed to
clobber IP0/IP1 and hence, should not result in a dynamic relocation.

Revert that change and in its place, issue an error when the target
symbol is undefined.

bfd/

	2020-09-10  Siddhesh Poyarekar  <siddesh.poyarekar@arm.com>

	* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Revert
	changes in 7e05773767.  Set
	error for undefined symbol in BFD_RELOC_AARCH64_BRANCH19 and
	BFD_RELOC_AARCH64_TSTBR14 relocations.

ld/

	2020-09-10  Siddhesh Poyarekar  <siddesh.poyarekar@arm.com>

	* testsuite/ld-aarch64/emit-relocs-560.d: Expect error instead
	of valid output.
This commit is contained in:
Siddhesh Poyarekar 2020-09-01 14:25:52 +05:30 committed by Siddhesh Poyarekar
parent 93d49941ed
commit c7cd291722
4 changed files with 32 additions and 24 deletions
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7
bfd/ChangeLog
View File

@ -1,3 +1,10 @@
2020-09-10 Siddhesh Poyarekar <siddesh.poyarekar@arm.com>
* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Revert
changes in 7e05773767820b441b23a16628b55c98cb1aef46. Set
error for undefined symbol in BFD_RELOC_AARCH64_BRANCH19 and
BFD_RELOC_AARCH64_TSTBR14 relocations.
2020-09-09 Nick Clifton <nickc@redhat.com>
* cofflink.c (coff_link_check_archive_element): Move the check for

37
bfd/elfnn-aarch64.c
View File

@ -5447,7 +5447,6 @@ 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);
@ -5469,8 +5468,6 @@ 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. */
@ -5806,23 +5803,12 @@ 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.
@ -5903,6 +5889,23 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
bfd_set_error (bfd_error_bad_value);
return bfd_reloc_notsupported;
}
value = _bfd_aarch64_elf_resolve_relocation (input_bfd, bfd_r_type,
place, value,
signed_addend,
weak_undef_p);
break;
case BFD_RELOC_AARCH64_BRANCH19:
case BFD_RELOC_AARCH64_TSTBR14:
if (h && h->root.type == bfd_link_hash_undefined)
{
_bfd_error_handler
/* xgettext:c-format */
(_("%pB: conditional branch to undefined symbol `%s' "
"not allowed"), input_bfd, h->root.root.string);
bfd_set_error (bfd_error_bad_value);
return bfd_reloc_notsupported;
}
/* Fall through. */
case BFD_RELOC_AARCH64_16:
@ -7968,8 +7971,6 @@ 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

5
ld/ChangeLog
View File

@ -1,3 +1,8 @@
2020-09-10 Siddhesh Poyarekar <siddesh.poyarekar@arm.com>
* testsuite/ld-aarch64/emit-relocs-560.d: Expect error instead
of valid output.
2020-09-10 H.J. Lu <hongjiu.lu@intel.com>
PR ld/26590

7
ld/testsuite/ld-aarch64/emit-relocs-560.d
View File

@ -1,8 +1,3 @@
#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
#error: .*: conditional branch to undefined symbol `bar' not allowed