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/* This test program is part of GDB, the GNU debugger.
Copyright 2021-2024 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Exercise AArch64's Memory Tagging Extension with tagged pointers. */
/* This test was based on the documentation for the AArch64 Memory Tagging
Extension from the Linux Kernel, found in the sources in
Documentation/arm64/memory-tagging-extension.rst. */
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/auxv.h>
#include <sys/mman.h>
#include <sys/prctl.h>
/* From arch/arm64/include/uapi/asm/hwcap.h */
#ifndef HWCAP2_MTE
#define HWCAP2_MTE (1 << 18)
#endif
/* From arch/arm64/include/uapi/asm/mman.h */
#ifndef PROT_MTE
#define PROT_MTE 0x20
#endif
#ifndef PR_SET_TAGGED_ADDR_CTRL
#define PR_SET_TAGGED_ADDR_CTRL 55
#define PR_TAGGED_ADDR_ENABLE (1UL << 0)
#endif
/* From include/uapi/linux/prctl.h */
#ifndef PR_MTE_TCF_SHIFT
#define PR_MTE_TCF_SHIFT 1
#define PR_MTE_TCF_SYNC (1UL << PR_MTE_TCF_SHIFT)
#define PR_MTE_TCF_ASYNC (2UL << PR_MTE_TCF_SHIFT)
#define PR_MTE_TAG_SHIFT 3
#endif
void
access_memory (unsigned char *tagged_ptr, unsigned char *untagged_ptr)
{
tagged_ptr[0] = 'a';
}
int
main (int argc, char **argv)
{
unsigned char *tagged_ptr;
unsigned char *untagged_ptr;
unsigned long page_sz = sysconf (_SC_PAGESIZE);
unsigned long hwcap2 = getauxval(AT_HWCAP2);
/* Bail out if MTE is not supported. */
if (!(hwcap2 & HWCAP2_MTE))
return 1;
/* Enable the tagged address ABI, synchronous MTE tag check faults and
allow all non-zero tags in the randomly generated set. */
if (prctl (PR_SET_TAGGED_ADDR_CTRL,
PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC
| (0xfffe << PR_MTE_TAG_SHIFT),
0, 0, 0))
{
perror ("prctl () failed");
return 1;
}
/* Create a mapping that will have PROT_MTE set. */
tagged_ptr = mmap (0, page_sz, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (tagged_ptr == MAP_FAILED)
{
perror ("mmap () failed");
return 1;
}
/* Create another mapping that won't have PROT_MTE set. */
untagged_ptr = mmap (0, page_sz, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (untagged_ptr == MAP_FAILED)
{
perror ("mmap () failed");
return 1;
}
/* Enable MTE on the above anonymous mmap. */
if (mprotect (tagged_ptr, page_sz, PROT_READ | PROT_WRITE | PROT_MTE))
{
perror ("mprotect () failed");
return 1;
}
access_memory (tagged_ptr, untagged_ptr);
return 0;
}
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