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powerpc64: Add memory protection key support [BZ #23202]

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The 32-bit protection key behavior is somewhat unclear on 32-bit powerpc,
so this change is restricted to the 64-bit variants.

Flag translation is needed because of hardware differences between the
POWER implementation (read and write flags) and the Intel implementation
(write and read+write flags).
This commit is contained in:
Florian Weimer
2020-02-14 20:55:39 +01:00
parent 2b7dc93f82
commit a803367bab
3 changed files with 145 additions and 0 deletions
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55
sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h Normal file
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/* Helper functions for manipulating memory protection keys, for powerpc64.
Copyright (C) 2017-2020 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
<http://www.gnu.org/licenses/>. */
#ifndef _ARCH_PKEY_H
#define _ARCH_PKEY_H
/* Read and write access bits in the AMR register. Needs to be
translated from and to PKEY_DISABLE_* flags. */
#define PKEY_AMR_READ 1UL
#define PKEY_AMR_WRITE 2UL
/* Return the value of the AMR register. */
static inline unsigned long int
pkey_read (void)
{
unsigned long int result;
__asm__ volatile ("mfspr %0, 13" : "=r" (result));
return result;
}
/* Overwrite the AMR register with VALUE. */
static inline void
pkey_write (unsigned long int value)
{
__asm__ volatile ("mtspr 13, %0" : : "r" (value));
}
/* Number of the largest supported key. This depends on the width of
the AMR register. */
#define PKEY_MAX (sizeof (unsigned long int) * 8 / 2 - 1)
_Static_assert (PKEY_MAX == 15 || PKEY_MAX == 31, "PKEY_MAX value");
/* Translate key number into AMR index position. */
static inline int
pkey_index (int key)
{
return 2 * (PKEY_MAX - key);
}
#endif /* _ARCH_PKEY_H */

42
sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_get.c Normal file
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/* Reading the per-thread memory protection key, powerpc64 version.
Copyright (C) 2017-2020 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
<http://www.gnu.org/licenses/>. */
#include <arch-pkey.h>
#include <errno.h>
#include <sys/mman.h>
int
pkey_get (int key)
{
if (key < 0 || key > PKEY_MAX)
{
__set_errno (EINVAL);
return -1;
}
unsigned int index = pkey_index (key);
unsigned long int amr = pkey_read ();
unsigned int bits = (amr >> index) & 3;
/* Translate from AMR values. PKEY_AMR_READ standing alone is not
currently representable. */
if (bits & PKEY_AMR_READ)
return PKEY_DISABLE_ACCESS;
else if (bits == PKEY_AMR_WRITE)
return PKEY_DISABLE_WRITE;
return 0;
}

48
sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_set.c Normal file
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/* Changing the per-thread memory protection key, powerpc64 version.
Copyright (C) 2017-2020 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
<http://www.gnu.org/licenses/>. */
#include <arch-pkey.h>
#include <errno.h>
#include <sys/mman.h>
int
pkey_set (int key, unsigned int rights)
{
if (key < 0 || key > PKEY_MAX || rights > 3)
{
__set_errno (EINVAL);
return -1;
}
/* Translate to AMR bit values. */
unsigned long int bits;
if (rights & PKEY_DISABLE_ACCESS)
/* The PKEY_DISABLE_WRITE bit does not matter. */
bits = PKEY_AMR_READ | PKEY_AMR_WRITE;
else if (rights == PKEY_DISABLE_WRITE)
bits = PKEY_AMR_WRITE;
else
bits = 0;
unsigned int index = pkey_index (key);
unsigned long int mask = 3UL << index;
unsigned long int amr = pkey_read ();
amr = (amr & ~mask) | (bits << index);
pkey_write (amr);
return 0;
}