code.ossystems Code Review - openembedded-core.git/blob

   1 From c7cd291722779c9d4703ed0010388fe394c644c8 Mon Sep 17 00:00:00 2001
   2 From: Siddhesh Poyarekar <siddesh.poyarekar@arm.com>
   3 Date: Tue, 1 Sep 2020 14:25:52 +0530
   4 Subject: [PATCH] aarch64: Return an error on conditional branch to an undefined symbol
   5
   6 The fix in 7e05773767820b441b23a16628b55c98cb1aef46 introduced a PLT
   7 for conditional jumps when the target symbol is undefined.  This is
   8 incorrect because conditional branch relocations are not allowed to
   9 clobber IP0/IP1 and hence, should not result in a dynamic relocation.
  10
  11 Revert that change and in its place, issue an error when the target
  12 symbol is undefined.
  13
  14 bfd/
  15
  16         2020-09-10  Siddhesh Poyarekar  <siddesh.poyarekar@arm.com>
  17
  18         * elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Revert
  19         changes in 7e05773767820b441b23a16628b55c98cb1aef46.  Set
  20         error for undefined symbol in BFD_RELOC_AARCH64_BRANCH19 and
  21         BFD_RELOC_AARCH64_TSTBR14 relocations.
  22
  23 ld/
  24
  25         2020-09-10  Siddhesh Poyarekar  <siddesh.poyarekar@arm.com>
  26
  27         * testsuite/ld-aarch64/emit-relocs-560.d: Expect error instead
  28         of valid output.
  29 ---
  30 Upstream-Status: Backport [https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c7cd291722779c9d4703ed0010388fe394c644c8]
  31 Signed-off-by: Khem Raj <raj.khem@gmail.com>
  32
  33  bfd/ChangeLog                             |  7 +++++
  34  bfd/elfnn-aarch64.c                       | 37 ++++++++++++-----------
  35  ld/ChangeLog                              |  5 +++
  36  ld/testsuite/ld-aarch64/emit-relocs-560.d |  7 +----
  37  4 files changed, 32 insertions(+), 24 deletions(-)
  38
  39 diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
  40 index 5b4c189b593..a9924e7ec56 100644
  41 --- a/bfd/elfnn-aarch64.c
  42 +++ b/bfd/elfnn-aarch64.c
  43 @@ -5447,7 +5447,6 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
  44    bfd_vma orig_value = value;
  45    bfd_boolean resolved_to_zero;
  46    bfd_boolean abs_symbol_p;
  47 -  bfd_boolean via_plt_p;
  48
  49    globals = elf_aarch64_hash_table (info);
  50
  51 @@ -5469,8 +5468,6 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
  52                   : bfd_is_und_section (sym_sec));
  53    abs_symbol_p = h != NULL && bfd_is_abs_symbol (&h->root);
  54
  55 -  via_plt_p = (globals->root.splt != NULL && h != NULL
  56 -              && h->plt.offset != (bfd_vma) - 1);
  57
  58    /* Since STT_GNU_IFUNC symbol must go through PLT, we handle
  59       it here if it is defined in a non-shared object.  */
  60 @@ -5806,23 +5803,12 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
  61         value += signed_addend;
  62        break;
  63
  64 -    case BFD_RELOC_AARCH64_BRANCH19:
  65 -    case BFD_RELOC_AARCH64_TSTBR14:
  66 -      /* A conditional branch to an undefined weak symbol is converted to a
  67 -        branch to itself.  */
  68 -      if (weak_undef_p && !via_plt_p)
  69 -       {
  70 -         value = _bfd_aarch64_elf_resolve_relocation (input_bfd, bfd_r_type,
  71 -                                                      place, value,
  72 -                                                      signed_addend,
  73 -                                                      weak_undef_p);
  74 -         break;
  75 -       }
  76 -      /* Fall through.  */
  77      case BFD_RELOC_AARCH64_CALL26:
  78      case BFD_RELOC_AARCH64_JUMP26:
  79        {
  80         asection *splt = globals->root.splt;
  81 +       bfd_boolean via_plt_p =
  82 +         splt != NULL && h != NULL && h->plt.offset != (bfd_vma) - 1;
  83
  84         /* A call to an undefined weak symbol is converted to a jump to
  85            the next instruction unless a PLT entry will be created.
  86 @@ -5903,6 +5889,23 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
  87           bfd_set_error (bfd_error_bad_value);
  88           return bfd_reloc_notsupported;
  89         }
  90 +      value = _bfd_aarch64_elf_resolve_relocation (input_bfd, bfd_r_type,
  91 +                                                  place, value,
  92 +                                                  signed_addend,
  93 +                                                  weak_undef_p);
  94 +      break;
  95 +
  96 +    case BFD_RELOC_AARCH64_BRANCH19:
  97 +    case BFD_RELOC_AARCH64_TSTBR14:
  98 +      if (h && h->root.type == bfd_link_hash_undefined)
  99 +       {
 100 +         _bfd_error_handler
 101 +           /* xgettext:c-format */
 102 +           (_("%pB: conditional branch to undefined symbol `%s' "
 103 +              "not allowed"), input_bfd, h->root.root.string);
 104 +         bfd_set_error (bfd_error_bad_value);
 105 +         return bfd_reloc_notsupported;
 106 +       }
 107        /* Fall through.  */
 108
 109      case BFD_RELOC_AARCH64_16:
 110 @@ -7968,8 +7971,6 @@ elfNN_aarch64_check_relocs (bfd *abfd, struct bfd_link_info *info,
 111             break;
 112           }
 113
 114 -       case BFD_RELOC_AARCH64_BRANCH19:
 115 -       case BFD_RELOC_AARCH64_TSTBR14:
 116         case BFD_RELOC_AARCH64_CALL26:
 117         case BFD_RELOC_AARCH64_JUMP26:
 118           /* If this is a local symbol then we resolve it
 119 diff --git a/ld/testsuite/ld-aarch64/emit-relocs-560.d b/ld/testsuite/ld-aarch64/emit-relocs-560.d
 120 index 153532457b4..8751b743bd4 100644
 121 --- a/ld/testsuite/ld-aarch64/emit-relocs-560.d
 122 +++ b/ld/testsuite/ld-aarch64/emit-relocs-560.d
 123 @@ -1,8 +1,3 @@
 124  #source: emit-relocs-560.s
 125  #ld: -shared
 126 -#readelf: -r
 127 -
 128 -Relocation section '.rela.plt' at offset 0x[0-9a-f]+ contains 2 entries:
 129 -  Offset          Info           Type           Sym. Value    Sym. Name \+ Addend
 130 -[0-9a-f]+  000100000402 R_AARCH64_JUMP_SL 0000000000000000 baz \+ 0
 131 -[0-9a-f]+  000200000402 R_AARCH64_JUMP_SL 0000000000000000 bar \+ 0
 132 +#error: .*: conditional branch to undefined symbol `bar' not allowed
 133 --
 134 2.29.2
 135