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/* ARMv8-M Security Extensions routines.
Copyright (C) 2015-2022 Free Software Foundation, Inc.
Contributed by ARM Ltd.
This file 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, or (at your option) any
later version.
This file 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#if __ARM_FEATURE_CMSE & 1
#include <arm_cmse.h>
/* ARM intrinsic function to perform a permission check on a given
address range. See ACLE changes for ARMv8-M. */
void *
__attribute__ ((warn_unused_result))
cmse_check_address_range (void *p, size_t size, int flags)
{
cmse_address_info_t permb, perme;
char *pb = (char *) p, *pe;
/* Check if the range wraps around. */
if (__UINTPTR_MAX__ - (__UINTPTR_TYPE__) p < size)
return NULL;
/* Check if an unknown flag is present. */
int known = CMSE_MPU_UNPRIV | CMSE_MPU_READWRITE | CMSE_MPU_READ;
int known_secure_level = CMSE_MPU_UNPRIV;
#if __ARM_FEATURE_CMSE & 2
known |= CMSE_AU_NONSECURE | CMSE_MPU_NONSECURE;
known_secure_level |= CMSE_MPU_NONSECURE;
#endif
if (flags & (~known))
return NULL;
/* Execute the right variant of the TT instructions. */
pe = pb + size - 1;
const int singleCheck
= (((__UINTPTR_TYPE__) pb ^ (__UINTPTR_TYPE__) pe) < 32);
switch (flags & known_secure_level)
{
case 0:
permb = cmse_TT (pb);
perme = singleCheck ? permb : cmse_TT (pe);
break;
case CMSE_MPU_UNPRIV:
permb = cmse_TTT (pb);
perme = singleCheck ? permb : cmse_TTT (pe);
break;
#if __ARM_FEATURE_CMSE & 2
case CMSE_MPU_NONSECURE:
permb = cmse_TTA (pb);
perme = singleCheck ? permb : cmse_TTA (pe);
break;
case CMSE_MPU_UNPRIV | CMSE_MPU_NONSECURE:
permb = cmse_TTAT (pb);
perme = singleCheck ? permb : cmse_TTAT (pe);
break;
#endif
default:
/* Invalid flag, eg. CMSE_MPU_NONSECURE specified but
__ARM_FEATURE_CMSE & 2 == 0. */
return NULL;
}
/* Check that the range does not cross MPU, SAU, or IDAU boundaries. */
if (permb.value != perme.value)
return NULL;
/* Check the permissions on the range. */
switch (flags & (~known_secure_level))
{
#if __ARM_FEATURE_CMSE & 2
case CMSE_MPU_READ | CMSE_MPU_READWRITE | CMSE_AU_NONSECURE:
case CMSE_MPU_READWRITE | CMSE_AU_NONSECURE:
return permb.flags.nonsecure_readwrite_ok ? p : NULL;
case CMSE_MPU_READ | CMSE_AU_NONSECURE:
return permb.flags.nonsecure_read_ok ? p : NULL;
case CMSE_AU_NONSECURE:
return permb.flags.secure ? NULL : p;
#endif
case CMSE_MPU_READ | CMSE_MPU_READWRITE:
case CMSE_MPU_READWRITE:
return permb.flags.readwrite_ok ? p : NULL;
case CMSE_MPU_READ:
return permb.flags.read_ok ? p : NULL;
default:
return NULL;
}
}
#endif /* __ARM_FEATURE_CMSE & 1. */
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