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74 lines
2.6 KiB
C
74 lines
2.6 KiB
C
/* Reading the per-thread memory protection key, AArch64 version.
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Copyright (C) 2024-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <arch-pkey.h>
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#include <errno.h>
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#include <sys/mman.h>
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int
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pkey_get (int key)
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{
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if (key < 0 || key > 15)
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{
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__set_errno (EINVAL);
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return -1;
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}
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unsigned long int por_el0 = pkey_read ();
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unsigned long int perm = (por_el0 >> (S1POE_BITS_PER_POI * key))
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& S1POE_PERM_MASK;
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/* The following mapping between POR permission bits (4 bits)
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and PKEY flags is supported:
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-WXR POR to PKEY_ mapping
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0000 => DISABLE_ACCESS | DISABLE_READ | DISABLE_WRITE | DISABLE_EXECUTE
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0001 => DISABLE_WRITE | DISABLE_EXECUTE (read-only)
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0010 => DISABLE_ACCESS | DISABLE_READ | DISABLE_WRITE (execute-only)
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0011 => DISABLE_WRITE (read-execute)
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0100 => DISABLE_READ | DISABLE_EXECUTE (write-only)
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0101 => DISABLE_EXECUTE (read-write)
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0110 => DISABLE_READ (execute-write)
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0111 => UNRESTRICTED (no restrictions, read-write-execute)
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else => undefined behavior
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Note that pkey_set and pkey_alloc would only set these specific
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values. The PKEY_DISABLE_ACCESS flag is redundant as it implies
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PKEY_DISABLE_READ | PKEY_DISABLE_WRITE but is kept for backward
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compatibility. */
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if (perm == S1POE_PERM_NO_ACCESS)
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return PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE | PKEY_DISABLE_EXECUTE
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| PKEY_DISABLE_READ;
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if (perm == S1POE_PERM_R)
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return PKEY_DISABLE_WRITE | PKEY_DISABLE_EXECUTE;
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if (perm == S1POE_PERM_X)
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return PKEY_DISABLE_ACCESS | PKEY_DISABLE_READ | PKEY_DISABLE_WRITE;
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if (perm == S1POE_PERM_RX)
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return PKEY_DISABLE_WRITE;
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if (perm == S1POE_PERM_W)
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return PKEY_DISABLE_READ | PKEY_DISABLE_EXECUTE;
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if (perm == S1POE_PERM_RW)
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return PKEY_DISABLE_EXECUTE;
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if (perm == S1POE_PERM_WX)
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return PKEY_DISABLE_READ;
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if (perm == S1POE_PERM_RWX)
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return PKEY_UNRESTRICTED;
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return PKEY_DISABLE_ACCESS;
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}
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