x86: Check ifunc resolver with CPU_FEATURE_USABLE [BZ #27072]

Check ifunc resolver with CPU_FEATURE_USABLE and tunables in dynamic and
static executables to verify that CPUID features are initialized early in
static PIE.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

sysdeps/x86/Makefile

@@ -10,6 +10,16 @@ sysdep_headers += sys/platform/x86.h
 tests += tst-get-cpu-features tst-get-cpu-features-static \
 	 tst-cpu-features-cpuinfo tst-cpu-features-supports
 tests-static += tst-get-cpu-features-static
+ifeq (yes,$(have-ifunc))
+tests += \
+  tst-ifunc-isa-1 \
+  tst-ifunc-isa-1-static \
+  tst-ifunc-isa-2 \
+  tst-ifunc-isa-2-static
+tests-static += \
+  tst-ifunc-isa-1-static \
+  tst-ifunc-isa-2-static
+endif
 ifeq (yes,$(enable-x86-isa-level))
 tests += tst-isa-level-1
 modules-names += tst-isa-level-mod-1-baseline \
@@ -40,6 +50,10 @@ $(objpfx)tst-isa-level-1.out: $(objpfx)tst-isa-level-mod-1-baseline.so \
 			      $(objpfx)tst-isa-level-mod-1-v3.so \
 			      $(objpfx)tst-isa-level-mod-1-v4.so
 endif
+ifneq ($(have-tunables),no)
+tst-ifunc-isa-2-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-SSE4_2,-AVX,-AVX2,-AVX512F
+tst-ifunc-isa-2-static-ENV = $(tst-ifunc-isa-2-ENV)
+endif
 endif
 
 ifeq ($(subdir),math)

sysdeps/x86/tst-ifunc-isa-1-static.c

@@ -0,0 +1 @@
+#include "tst-ifunc-isa-1.c"

sysdeps/x86/tst-ifunc-isa-1.c

@@ -0,0 +1,30 @@
+/* Check IFUNC resolver with CPU_FEATURE_USABLE.
+   Copyright (C) 2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include "tst-ifunc-isa.h"
+
+static int
+do_test (void)
+{
+  enum isa value = foo ();
+  enum isa expected = get_isa ();
+  return value == expected ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
+#include <support/test-driver.c>

sysdeps/x86/tst-ifunc-isa-2-static.c

@@ -0,0 +1 @@
+#include "tst-ifunc-isa-2.c"

sysdeps/x86/tst-ifunc-isa-2.c

@@ -0,0 +1,34 @@
+/* Check IFUNC resolver with CPU_FEATURE_USABLE and tunables.
+   Copyright (C) 2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include "tst-ifunc-isa.h"
+#include <support/test-driver.h>
+
+static int
+do_test (void)
+{
+  /* CPU must support SSE2.  */
+  if (!__builtin_cpu_supports ("sse2"))
+    return EXIT_UNSUPPORTED;
+  enum isa value = foo ();
+  /* All ISAs, but SSE2, are disabled by tunables.  */
+  return value == sse2 ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
+#include <support/test-driver.c>

sysdeps/x86/tst-ifunc-isa.h

@@ -0,0 +1,104 @@
+/* IFUNC resolver with CPU_FEATURE_USABLE.
+   Copyright (C) 2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/platform/x86.h>
+
+enum isa
+{
+  none,
+  sse2,
+  sse4_2,
+  avx,
+  avx2,
+  avx512f
+};
+
+enum isa
+get_isa (void)
+{
+  if (CPU_FEATURE_USABLE (AVX512F))
+    return avx512f;
+  if (CPU_FEATURE_USABLE (AVX2))
+    return avx2;
+  if (CPU_FEATURE_USABLE (AVX))
+    return avx;
+  if (CPU_FEATURE_USABLE (SSE4_2))
+    return sse4_2;
+  if (CPU_FEATURE_USABLE (SSE2))
+    return sse2;
+  return none;
+}
+
+static int
+isa_sse2 (void)
+{
+  return sse2;
+}
+
+static int
+isa_sse4_2 (void)
+{
+  return sse4_2;
+}
+
+static int
+isa_avx (void)
+{
+  return avx;
+}
+
+static int
+isa_avx2 (void)
+{
+  return avx2;
+}
+
+static int
+isa_avx512f (void)
+{
+  return avx512f;
+}
+
+static int
+isa_none (void)
+{
+  return none;
+}
+
+int foo (void) __attribute__ ((ifunc ("foo_ifunc")));
+
+void *
+foo_ifunc (void)
+{
+  switch (get_isa ())
+    {
+    case avx512f:
+      return isa_avx512f;
+    case avx2:
+      return isa_avx2;
+    case avx:
+      return isa_avx;
+    case sse4_2:
+      return isa_sse4_2;
+    case sse2:
+      return isa_sse2;
+    default:
+      break;
+    }
+  return isa_none;
+}