From 5644ef5461b5d3ff266206d8ee70d4b575ea6658 Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@gmail.com>
Date: Wed, 20 Jul 2011 21:21:03 -0400
Subject: 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.
---
 sysdeps/x86_64/dl-trampoline.S | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

(limited to 'sysdeps/x86_64/dl-trampoline.S')

diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
index 5564a11af2..1b97929aaa 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
 
-- 
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