powerpc: Fix VSCR position in ucontext (bug 24088)

This patch fix VSCR position on ucontext. VSCR was read in the wrong
position on ucontext structure because it was ignoring the machine
endianess.

	[BZ #24088]
	* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h (vscr_t): Added
	ifdef to fix read of VSCR.
	* sysdeps/powerpc/powerpc64/Makefile [$subdir == stdlib]: Add
	tst-ucontext-ppc64-vscr.c to test list.
	* sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c: New test file.

Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

1 files changed, 84 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c b/sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c
new file mode 100644
index 0000000000..2dcf5bb634
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c
@@ -0,0 +1,84 @@
+/* Test if POWER vscr read by ucontext.
+   Copyright (C) 2018 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 <support/check.h>
+#include <sys/auxv.h>
+#include <ucontext.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <altivec.h>
+
+#define SAT 0x1
+
+/* This test is supported only on POWER 5 or higher.  */
+#define PPC_CPU_SUPPORTED (PPC_FEATURE_POWER5 | PPC_FEATURE_POWER5_PLUS | \
+			   PPC_FEATURE_ARCH_2_05 | PPC_FEATURE_ARCH_2_06 | \
+			   PPC_FEATURE2_ARCH_2_07)
+static int
+do_test (void)
+{
+
+  if (!(getauxval(AT_HWCAP2) & PPC_CPU_SUPPORTED))
+    {
+      if (!(getauxval(AT_HWCAP) & PPC_CPU_SUPPORTED))
+      FAIL_UNSUPPORTED("This test is unsupported on POWER < 5\n");
+    }
+
+  uint32_t vscr[4] __attribute__ ((aligned (16)));
+  uint32_t* vscr_ptr = vscr;
+  uint32_t vscr_word;
+  ucontext_t ucp;
+  __vector __int128_t v0 = {0};
+  __vector __int128_t v1 = {0};
+
+  /* Set SAT bit in VSCR register.  */
+  asm volatile (".machine push;\n"
+		".machine \"power5\";\n"
+		"vspltisb %0,0;\n"
+		"vspltisb %1,-1;\n"
+		"vpkuwus %0,%0,%1;\n"
+		"mfvscr %0;\n"
+		"stvx %0,0,%2;\n"
+		".machine pop;"
+		: "=v" (v0), "=v" (v1)
+		: "r" (vscr_ptr)
+		: "memory");
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+  vscr_word = vscr[0];
+#else
+  vscr_word = vscr[3];
+#endif
+
+  if ((vscr_word & SAT) != SAT)
+    {
+      FAIL_EXIT1("FAIL: SAT bit is not set.\n");
+    }
+
+  if (getcontext (&ucp))
+    {
+      FAIL_EXIT1("FAIL: getcontext error\n");
+    }
+  if (ucp.uc_mcontext.v_regs->vscr.vscr_word != vscr_word)
+    {
+      FAIL_EXIT1("FAIL: ucontext vscr does not match with vscr\n");
+    }
+  return 0;
+}
+
+#include <support/test-driver.c>