[PATCH v3] powerpc: Add tests for __ppc_set_ppr_* functions.

[Wainer dos Santos Moschetta <wainersm at linux dot vnet dot ibm dot com>]

Changes since v2:
 - Enabled tests on 32-bit PowerPC.
 - Improved code comments.

--- 8< ---
The sys/platform/ppc.h header defines a class of __ppc_set_ppr functions
used to set the Program Priority Register (PPR) in PowerPC.
This patch implements test cases for these functions.

Tested on ppc64le, ppc64, and ppc.

2017-02-07  Wainer dos Santos Moschetta  <wainersm@linux.vnet.ibm.com>

	* sysdeps/powerpc/tst-set_ppr.c: New file.
	Implement test cases for __ppc_set_ppr_* functions.
	* sysdeps/powerpc/Makefile ($(subdir),misc): Add tst-set_ppr
	in the list of tests.
---
 sysdeps/powerpc/Makefile      |   1 +
 sysdeps/powerpc/tst-set_ppr.c | 102 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 sysdeps/powerpc/tst-set_ppr.c

diff --git a/sysdeps/powerpc/Makefile b/sysdeps/powerpc/Makefile
index 099fbf6..933810f 100644
--- a/sysdeps/powerpc/Makefile
+++ b/sysdeps/powerpc/Makefile
@@ -34,6 +34,7 @@ endif
 ifeq ($(subdir),misc)
 sysdep_headers += sys/platform/ppc.h
 tests += test-gettimebase
+tests += tst-set_ppr
 endif
 
 ifneq (,$(filter %le,$(config-machine)))
diff --git a/sysdeps/powerpc/tst-set_ppr.c b/sysdeps/powerpc/tst-set_ppr.c
new file mode 100644
index 0000000..a4bf526
--- /dev/null
+++ b/sysdeps/powerpc/tst-set_ppr.c
@@ -0,0 +1,102 @@
+/* Test the implementation of __ppc_set_ppr_* functions.
+   Copyright (C) 2017 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 <dl-procinfo.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <sys/auxv.h>
+
+#include <sys/platform/ppc.h>
+
+#include <support/test-driver.h>
+
+#ifdef __powerpc64__
+  typedef uint64_t ppr_t;
+# define MFPPR "mfppr"
+  /* The thread priority value is obtained from bits 11:13.  */
+# define EXTRACT_THREAD_PRIORITY(x) ((x >> 50) & 7)
+#else
+  typedef uint32_t ppr_t;
+# define MFPPR "mfppr32"
+  /* For 32-bit, the upper 32 bits of the Program Priority Register (PPR)
+     are used, so the thread priority value is obtained from bits 43:46.  */
+# define EXTRACT_THREAD_PRIORITY(x) ((x >> 18) & 7)
+#endif /* !__powerpc64__ */
+
+/* Read the thread priority value set in the PPR.  */
+static __inline__ ppr_t
+get_thread_priority (void)
+{
+  /* Read the PPR.  */
+  ppr_t ppr;
+  asm volatile (MFPPR" %0" : "=r"(ppr));
+  /* Return the thread priority value.  */
+  return EXTRACT_THREAD_PRIORITY (ppr);
+}
+
+/* Check the thread priority bits of PPR are set as expected. */
+uint8_t
+check_thread_priority (uint8_t expected)
+{
+  ppr_t actual = get_thread_priority ();
+
+  if (actual != expected)
+    {
+      printf ("FAIL: Expected %"PRIu8" got %"PRIuMAX".\n", expected, (uintmax_t) actual);
+      return 1;
+    }
+  printf ("PASS: Thread priority set to %"PRIu8" correctly.\n", expected);
+  return 0;
+}
+
+/* The Power ISA 2.06 allows the following thread priorities for any
+   problem state program: low (2), medium low (3), and medium (4).
+   Power ISA 2.07b added very low (1).
+   Check whether the values set by __ppc_set_ppr_* are correct.  */
+static int
+do_test (void)
+{
+  /* Check for the minimum required Power ISA to run these tests.  */
+  if ((getauxval (AT_HWCAP) & PPC_FEATURE_ARCH_2_06) == 0)
+    {
+      printf ("Requires an environment that implements the Power ISA version"
+              " 2.06 or greater.\n");
+      return EXIT_UNSUPPORTED;
+    }
+
+  uint8_t rc = 0;
+
+#ifdef _ARCH_PWR8
+  __ppc_set_ppr_very_low ();
+  rc |= check_thread_priority (1);
+#endif /* _ARCH_PWR8 */
+
+  __ppc_set_ppr_low ();
+  rc |= check_thread_priority (2);
+
+  __ppc_set_ppr_med_low ();
+  rc |= check_thread_priority (3);
+
+  __ppc_set_ppr_med ();
+  rc |= check_thread_priority (4);
+
+  return rc;
+}
+
+#include <support/test-driver.c>
-- 
1.9.1