gdb/arch/aarch64-mte-linux.c

   1 /* Common Linux target-dependent functionality for AArch64 MTE
   2
   3    Copyright (C) 2021-2024 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "arch/aarch64-mte-linux.h"
  21
  22 /* See arch/aarch64-mte-linux.h */
  23
  24 void
  25 aarch64_mte_pack_tags (gdb::byte_vector &tags)
  26 {
  27   /* Nothing to pack?  */
  28   if (tags.empty ())
  29     return;
  30
  31   /* If the tags vector has an odd number of elements, add another
  32      zeroed-out element to make it even.  This facilitates packing.  */
  33   if ((tags.size () % 2) != 0)
  34     tags.emplace_back (0);
  35
  36   for (int unpacked = 0, packed = 0; unpacked < tags.size ();
  37        unpacked += 2, packed++)
  38     tags[packed] = (tags[unpacked + 1] << 4) | tags[unpacked];
  39
  40   /* Now we have half the size.  */
  41   tags.resize (tags.size () / 2);
  42 }
  43
  44 /* See arch/aarch64-mte-linux.h */
  45
  46 void
  47 aarch64_mte_unpack_tags (gdb::byte_vector &tags, bool skip_first)
  48 {
  49   /* Nothing to unpack?  */
  50   if (tags.empty ())
  51     return;
  52
  53   /* An unpacked MTE tags vector will have twice the number of elements
  54      compared to an unpacked one.  */
  55   gdb::byte_vector unpacked_tags (tags.size () * 2);
  56
  57   int unpacked = 0, packed = 0;
  58
  59   if (skip_first)
  60     {
  61       /* We are not interested in the first unpacked element, just discard
  62          it.  */
  63       unpacked_tags[unpacked] = (tags[packed] >> 4) & 0xf;
  64       unpacked++;
  65       packed++;
  66     }
  67
  68   for (; packed < tags.size (); unpacked += 2, packed++)
  69     {
  70       unpacked_tags[unpacked] = tags[packed] & 0xf;
  71       unpacked_tags[unpacked + 1] = (tags[packed] >> 4) & 0xf;
  72     }
  73
  74   /* Update the original tags vector.  */
  75   tags = std::move (unpacked_tags);
  76 }
  77