commit a803367bab167f5ec4fde1f0d0ec447707c29520

Author: Florian Weimer <fweimer@redhat.com>

Date:   Fri Feb 14 20:55:39 2020 +0100

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

    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).

diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h b/sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h

new file mode 100644

index 0000000000000000..623b073d5a585d51

--- /dev/null

+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/arch-pkey.h

@@ -0,0 +1,55 @@

+/* 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 */

diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_get.c b/sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_get.c

new file mode 100644

index 0000000000000000..856ba061b90eabd2

--- /dev/null

+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_get.c

@@ -0,0 +1,42 @@

+/* 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;

+}

diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_set.c b/sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_set.c

new file mode 100644

index 0000000000000000..20b372ee2983abd5

--- /dev/null

+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/pkey_set.c

@@ -0,0 +1,48 @@

+/* 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;

+}