x86, fpu: Use static_cpu_has_safe before alternatives
authorBorislav Petkov <bp@suse.de>
Sun, 9 Jun 2013 10:07:34 +0000 (12:07 +0200)
committerH. Peter Anvin <hpa@linux.intel.com>
Fri, 21 Jun 2013 00:38:22 +0000 (17:38 -0700)
commit5f8c4218148822fde6eebbeefc34bd0a6061e031
tree1490d5de1b80ed71c737a28841cc2dcae930ca71
parent4a90a99c4f8002edaa6be11bd756872ebf3f3d97
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: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1370772454-6106-6-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
arch/x86/include/asm/fpu-internal.h