From c7cd291722779c9d4703ed0010388fe394c644c8 Mon Sep 17 00:00:00 2001 From: Siddhesh Poyarekar Date: Tue, 1 Sep 2020 14:25:52 +0530 Subject: [PATCH] aarch64: Return an error on conditional branch to an undefined symbol The fix in 7e05773767820b441b23a16628b55c98cb1aef46 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 * 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. ld/ 2020-09-10 Siddhesh Poyarekar * testsuite/ld-aarch64/emit-relocs-560.d: Expect error instead of valid output. --- Upstream-Status: Backport [https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c7cd291722779c9d4703ed0010388fe394c644c8] Signed-off-by: Khem Raj bfd/ChangeLog | 7 +++++ bfd/elfnn-aarch64.c | 37 ++++++++++++----------- ld/ChangeLog | 5 +++ ld/testsuite/ld-aarch64/emit-relocs-560.d | 7 +---- 4 files changed, 32 insertions(+), 24 deletions(-) diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c index 5b4c189b593..a9924e7ec56 100644 --- a/bfd/elfnn-aarch64.c +++ b/bfd/elfnn-aarch64.c @@ -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 diff --git a/ld/testsuite/ld-aarch64/emit-relocs-560.d b/ld/testsuite/ld-aarch64/emit-relocs-560.d index 153532457b4..8751b743bd4 100644 --- a/ld/testsuite/ld-aarch64/emit-relocs-560.d +++ b/ld/testsuite/ld-aarch64/emit-relocs-560.d @@ -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 -- 2.29.2