x86, fpu: Use static_cpu_has_safe before alternatives

The call stack below shows how this happens: basically eager_fpu_init()
calls __thread_fpu_begin(current) which then does if (!use_eager_fpu()),
which, in turn, uses static_cpu_has.

And we're executing before alternatives so static_cpu_has doesn't work
there yet.

Use the safe variant in this path which becomes optimal after
alternatives have run.

WARNING: at arch/x86/kernel/cpu/common.c:1368 warn_pre_alternatives+0x1e/0x20()
You're using static_cpu_has before alternatives have run!
Modules linked in:
Pid: 0, comm: swapper Not tainted 3.9.0-rc8+ #1
Call Trace:
 warn_slowpath_common
 warn_slowpath_fmt
 ? fpu_finit
 warn_pre_alternatives
 eager_fpu_init
 fpu_init
 cpu_init
 trap_init
 start_kernel
 ? repair_env_string
 x86_64_start_reservations
 x86_64_start_kernel
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1370772454-6106-6-git-send-email-bp@alien8.deSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/fpu-internal.h

@@ -343,7 +343,7 @@ static inline void __thread_fpu_end(struct task_struct *tsk)
 
 static inline void __thread_fpu_begin(struct task_struct *tsk)
 {
-	if (!use_eager_fpu())
+	if (!static_cpu_has_safe(X86_FEATURE_EAGER_FPU))
 		clts();
 	__thread_set_has_fpu(tsk);
 }