From 722bff7a4ccceeded69ac8c412ff5ee5859964e7 Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@gmail.com>
Date: Wed, 20 Jul 2011 21:21:03 -0400
Subject: [PATCH] Fix check for AVX enablement

The AVX bit is set if the CPU supports AVX.  But this doesn't mean the
kernel does.  Add checks according to Intel's documentation.
(cherry picked from commit 5644ef5461b5d3ff266206d8ee70d4b575ea6658)
---
 ChangeLog                      |  9 +++++++++
 elf/tst-audit4.c               | 22 ++++++++++++++++++----
 elf/tst-audit6.c               | 22 ++++++++++++++++++----
 sysdeps/x86_64/dl-trampoline.S | 17 ++++++++++++-----
 4 files changed, 57 insertions(+), 13 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 515f22c0462..9b130a5cd7c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2011-07-20  Ulrich Drepper  <drepper@gmail.com>
+
+	[BZ #13007]
+	* sysdeps/x86_64/dl-trampoline.S (_dl_runtime_profile): More complete
+	check for AVX enablement so that we don't crash with old kernels and
+	new hardware.
+	* elf/tst-audit4.c: Add same checks here.
+	* elf/tst-audit6.c: Likewise.
+
 2011-07-20  Ulrich Drepper  <drepper@gmail.com>
 
 	[BZ #12852]
diff --git a/elf/tst-audit4.c b/elf/tst-audit4.c
index b17d4a61a79..c4f1d5bdb9c 100644
--- a/elf/tst-audit4.c
+++ b/elf/tst-audit4.c
@@ -6,16 +6,30 @@
 #include <cpuid.h>
 #include <immintrin.h>
 
+
+static int
+avx_enabled (void)
+{
+  unsigned int eax, ebx, ecx, edx;
+
+  if (__get_cpuid (1, &eax, &ebx, &ecx, &edx) == 0
+      || (ecx & (bit_AVX | bit_OSXSAVE)) != (bit_AVX | bit_OSXSAVE))
+    return 0;
+
+  /* Check the OS has AVX and SSE saving enabled.  */
+  asm ("xgetbv" : "=a" (eax), "=d" (edx) : "c" (0));
+
+  return (eax & 6) == 6;
+}
+
+
 extern __m256i audit_test (__m256i, __m256i, __m256i, __m256i,
 			   __m256i, __m256i, __m256i, __m256i);
 int
 main (void)
 {
-  unsigned int eax, ebx, ecx, edx;
-
   /* Run AVX test only if AVX is supported.  */
-  if (__get_cpuid (1, &eax, &ebx, &ecx, &edx)
-      && (ecx & bit_AVX))
+  if (avx_enabled ())
     {
       __m256i ymm = _mm256_setzero_si256 ();
       __m256i ret = audit_test (ymm, ymm, ymm, ymm, ymm, ymm, ymm, ymm);
diff --git a/elf/tst-audit6.c b/elf/tst-audit6.c
index 1f6dcb16e9a..64209a152e7 100644
--- a/elf/tst-audit6.c
+++ b/elf/tst-audit6.c
@@ -8,14 +8,28 @@
 extern __m128i audit_test (__m128i, __m128i, __m128i, __m128i,
 			   __m128i, __m128i, __m128i, __m128i);
 
-int
-main (void)
+
+static int
+avx_enabled (void)
 {
   unsigned int eax, ebx, ecx, edx;
 
+  if (__get_cpuid (1, &eax, &ebx, &ecx, &edx) == 0
+      || (ecx & (bit_AVX | bit_OSXSAVE)) != (bit_AVX | bit_OSXSAVE))
+    return 0;
+
+  /* Check the OS has AVX and SSE saving enabled.  */
+  asm ("xgetbv" : "=a" (eax), "=d" (edx) : "c" (0));
+
+  return (eax & 6) == 6;
+}
+
+
+int
+main (void)
+{
   /* Run AVX test only if AVX is supported.  */
-  if (__get_cpuid (1, &eax, &ebx, &ecx, &edx)
-      && (ecx & bit_AVX))
+  if (avx_enabled ())
     {
       __m128i xmm = _mm_setzero_si128 ();
       __m128i ret = audit_test (xmm, xmm, xmm, xmm, xmm, xmm, xmm, xmm);
diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
index 5564a11af29..1b97929aaa1 100644
--- a/sysdeps/x86_64/dl-trampoline.S
+++ b/sysdeps/x86_64/dl-trampoline.S
@@ -1,5 +1,5 @@
 /* PLT trampolines.  x86-64 version.
-   Copyright (C) 2004, 2005, 2007, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005, 2007, 2009, 2011 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
@@ -139,10 +139,17 @@ L(have_avx):
 	movl	$1, %eax
 	cpuid
 	movq	%r11,%rbx		# Restore rbx
-	movl	$1, %eax
-	testl	$(1 << 28), %ecx
-	jne	2f
-	negl	%eax
+	xorl	%eax, %eax
+	// AVX and XSAVE supported?
+	testl	$((1 << 28) | (1 << 27)), %ecx
+	je	2f
+	xorl	%ecx, %ecx
+	// Get XFEATURE_ENABLED_MASK
+	xgetbv
+	andl	$0x6, %eax
+	cmpl	$0x6, %eax
+	// Nonzero if SSE and AVX state saving is enabled.
+	sete	%al
 2:	movl	%eax, L(have_avx)(%rip)
 	cmpl	$0, %eax
 
-- 
2.47.2