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/* Reading the per-thread memory protection key, AArch64 version.
Copyright (C) 2024-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <arch-pkey.h>
#include <errno.h>
#include <sys/mman.h>
int
pkey_get (int key)
{
if (key < 0 || key > 15)
{
__set_errno (EINVAL);
return -1;
}
unsigned long int por_el0 = pkey_read ();
unsigned long int perm = (por_el0 >> (S1POE_BITS_PER_POI * key))
& S1POE_PERM_MASK;
/* The following mapping between POR permission bits (4 bits)
and PKEY flags is supported:
-WXR POR to PKEY_ mapping
0000 => DISABLE_ACCESS | DISABLE_READ | DISABLE_WRITE | DISABLE_EXECUTE
0001 => DISABLE_WRITE | DISABLE_EXECUTE (read-only)
0010 => DISABLE_ACCESS | DISABLE_READ | DISABLE_WRITE (execute-only)
0011 => DISABLE_WRITE (read-execute)
0100 => DISABLE_READ | DISABLE_EXECUTE (write-only)
0101 => DISABLE_EXECUTE (read-write)
0110 => DISABLE_READ (execute-write)
0111 => UNRESTRICTED (no restrictions, read-write-execute)
else => undefined behavior
Note that pkey_set and pkey_alloc would only set these specific
values. The PKEY_DISABLE_ACCESS flag is redundant as it implies
PKEY_DISABLE_READ | PKEY_DISABLE_WRITE but is kept for backward
compatibility. */
if (perm == S1POE_PERM_NO_ACCESS)
return PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE | PKEY_DISABLE_EXECUTE
| PKEY_DISABLE_READ;
if (perm == S1POE_PERM_R)
return PKEY_DISABLE_WRITE | PKEY_DISABLE_EXECUTE;
if (perm == S1POE_PERM_X)
return PKEY_DISABLE_ACCESS | PKEY_DISABLE_READ | PKEY_DISABLE_WRITE;
if (perm == S1POE_PERM_RX)
return PKEY_DISABLE_WRITE;
if (perm == S1POE_PERM_W)
return PKEY_DISABLE_READ | PKEY_DISABLE_EXECUTE;
if (perm == S1POE_PERM_RW)
return PKEY_DISABLE_EXECUTE;
if (perm == S1POE_PERM_WX)
return PKEY_DISABLE_READ;
if (perm == S1POE_PERM_RWX)
return PKEY_UNRESTRICTED;
return PKEY_DISABLE_ACCESS;
}
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