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

   1 /* This test program is part of GDB, the GNU debugger.
   2
   3    Copyright 2021-2024 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 #ifndef HWCAP2_MTE
  34 #define HWCAP2_MTE              (1 << 18)
  35 #endif
  36
  37 /* From arch/arm64/include/uapi/asm/mman.h */
  38 #ifndef PROT_MTE
  39 #define PROT_MTE  0x20
  40 #endif
  41
  42 #ifndef PR_SET_TAGGED_ADDR_CTRL
  43 #define PR_SET_TAGGED_ADDR_CTRL 55
  44 #define PR_TAGGED_ADDR_ENABLE   (1UL << 0)
  45 #endif
  46
  47 /* From include/uapi/linux/prctl.h */
  48 #ifndef PR_MTE_TCF_SHIFT
  49 #define PR_MTE_TCF_SHIFT        1
  50 #define PR_MTE_TCF_SYNC         (1UL << PR_MTE_TCF_SHIFT)
  51 #define PR_MTE_TCF_ASYNC        (2UL << PR_MTE_TCF_SHIFT)
  52 #define PR_MTE_TAG_SHIFT        3
  53 #endif
  54
  55 void
  56 access_memory (unsigned char *tagged_ptr, unsigned char *untagged_ptr)
  57 {
  58   tagged_ptr[0] = 'a';
  59 }
  60
  61 int
  62 main (int argc, char **argv)
  63 {
  64   unsigned char *tagged_ptr;
  65   unsigned char *untagged_ptr;
  66   unsigned long page_sz = sysconf (_SC_PAGESIZE);
  67   unsigned long hwcap2 = getauxval(AT_HWCAP2);
  68
  69   /* Bail out if MTE is not supported.  */
  70   if (!(hwcap2 & HWCAP2_MTE))
  71     return 1;
  72
  73   /* Enable the tagged address ABI, synchronous MTE tag check faults and
  74      allow all non-zero tags in the randomly generated set.  */
  75   if (prctl (PR_SET_TAGGED_ADDR_CTRL,
  76              PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC
  77              | (0xfffe << PR_MTE_TAG_SHIFT),
  78              0, 0, 0))
  79     {
  80       perror ("prctl () failed");
  81       return 1;
  82     }
  83
  84   /* Create a mapping that will have PROT_MTE set.  */
  85   tagged_ptr = mmap (0, page_sz, PROT_READ | PROT_WRITE,
  86                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  87   if (tagged_ptr == MAP_FAILED)
  88     {
  89       perror ("mmap () failed");
  90       return 1;
  91     }
  92
  93   /* Create another mapping that won't have PROT_MTE set.  */
  94   untagged_ptr = mmap (0, page_sz, PROT_READ | PROT_WRITE,
  95                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  96   if (untagged_ptr == MAP_FAILED)
  97     {
  98       perror ("mmap () failed");
  99       return 1;
 100     }
 101
 102   /* Enable MTE on the above anonymous mmap.  */
 103   if (mprotect (tagged_ptr, page_sz, PROT_READ | PROT_WRITE | PROT_MTE))
 104     {
 105       perror ("mprotect () failed");
 106       return 1;
 107     }
 108
 109   access_memory (tagged_ptr, untagged_ptr);
 110
 111   return 0;
 112 }