From: Borislav Petkov Date: Sun, 9 Jun 2013 10:07:34 +0000 (+0200) Subject: x86, fpu: Use static_cpu_has_safe before alternatives X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=5f8c4218148822fde6eebbeefc34bd0a6061e031;p=openwrt%2Fstaging%2Fblogic.git 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 Link: http://lkml.kernel.org/r/1370772454-6106-6-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin --- diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index fb808d71cd70..4d0bda7b11e3 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/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); }