gdb/testsuite/gdb.arch/aarch64-mte.c

   1 /* This test program is part of GDB, the GNU debugger.
   2
   3    Copyright 2021-2022 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Exercise AArch64's Memory Tagging Extension with tagged pointers.  */
  19
  20 /* This test was based on the documentation for the AArch64 Memory Tagging
  21    Extension from the Linux Kernel, found in the sources in
  22    Documentation/arm64/memory-tagging-extension.rst.  */
  23
  24 #include <errno.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <unistd.h>
  28 #include <sys/auxv.h>
  29 #include <sys/mman.h>
  30 #include <sys/prctl.h>
  31
  32 /* From arch/arm64/include/uapi/asm/hwcap.h */
  33 #define HWCAP2_MTE              (1 << 18)
  34
  35 /* From arch/arm64/include/uapi/asm/mman.h */
  36 #define PROT_MTE  0x20
  37
  38 /* From include/uapi/linux/prctl.h */
  39 #define PR_SET_TAGGED_ADDR_CTRL 55
  40 #define PR_GET_TAGGED_ADDR_CTRL 56
  41 #define PR_TAGGED_ADDR_ENABLE   (1UL << 0)
  42 #define PR_MTE_TCF_SHIFT        1
  43 #define PR_MTE_TCF_NONE         (0UL << PR_MTE_TCF_SHIFT)
  44 #define PR_MTE_TCF_SYNC         (1UL << PR_MTE_TCF_SHIFT)
  45 #define PR_MTE_TCF_ASYNC        (2UL << PR_MTE_TCF_SHIFT)
  46 #define PR_MTE_TCF_MASK         (3UL << PR_MTE_TCF_SHIFT)
  47 #define PR_MTE_TAG_SHIFT        3
  48 #define PR_MTE_TAG_MASK         (0xffffUL << PR_MTE_TAG_SHIFT)
  49
  50 void
  51 access_memory (unsigned char *tagged_ptr, unsigned char *untagged_ptr)
  52 {
  53   tagged_ptr[0] = 'a';
  54 }
  55
  56 int
  57 main (int argc, char **argv)
  58 {
  59   unsigned char *tagged_ptr;
  60   unsigned char *untagged_ptr;
  61   unsigned long page_sz = sysconf (_SC_PAGESIZE);
  62   unsigned long hwcap2 = getauxval(AT_HWCAP2);
  63
  64   /* Bail out if MTE is not supported.  */
  65   if (!(hwcap2 & HWCAP2_MTE))
  66     return 1;
  67
  68   /* Enable the tagged address ABI, synchronous MTE tag check faults and
  69      allow all non-zero tags in the randomly generated set.  */
  70   if (prctl (PR_SET_TAGGED_ADDR_CTRL,
  71              PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC
  72              | (0xfffe << PR_MTE_TAG_SHIFT),
  73              0, 0, 0))
  74     {
  75       perror ("prctl () failed");
  76       return 1;
  77     }
  78
  79   /* Create a mapping that will have PROT_MTE set.  */
  80   tagged_ptr = mmap (0, page_sz, PROT_READ | PROT_WRITE,
  81                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  82   if (tagged_ptr == MAP_FAILED)
  83     {
  84       perror ("mmap () failed");
  85       return 1;
  86     }
  87
  88   /* Create another mapping that won't have PROT_MTE set.  */
  89   untagged_ptr = mmap (0, page_sz, PROT_READ | PROT_WRITE,
  90                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  91   if (untagged_ptr == MAP_FAILED)
  92     {
  93       perror ("mmap () failed");
  94       return 1;
  95     }
  96
  97   /* Enable MTE on the above anonymous mmap.  */
  98   if (mprotect (tagged_ptr, page_sz, PROT_READ | PROT_WRITE | PROT_MTE))
  99     {
 100       perror ("mprotect () failed");
 101       return 1;
 102     }
 103
 104   access_memory (tagged_ptr, untagged_ptr);
 105
 106   return 0;
 107 }