1  /* Helpers for On-demand PLT fixup for shared objects.  ARC version.
       2     Copyright (C) 2020-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library.  If not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  /* PLT jump into resolver passes PC of PLTn, while _dl_fixup expects the
      20     address of corresponding .rela.plt entry.
      21  
      22      - @plt0: runtime pc of first plt entry (DT_PLTGOT)
      23      - @pltn: runtime pc of plt entry being resolved
      24      - @size: size of .plt.rela entry (unused).  */
      25  static inline uintptr_t
      26  reloc_index (uintptr_t plt0, uintptr_t pltn, size_t size)
      27  {
      28    unsigned long int idx = pltn - plt0;
      29  
      30    /* PLT trampoline is 16 bytes.  */
      31    idx /= 16;
      32  
      33    /* Exclude PLT0 and PLT1.  */
      34    return idx - 2;
      35  }
      36  
      37  static inline uintptr_t
      38  reloc_offset (uintptr_t plt0, uintptr_t pltn)
      39  {
      40    size_t sz = sizeof (ElfW(Rela));
      41    return reloc_index (plt0, pltn, sz) * sz;
      42  }