From: Borislav Petkov <[email protected]> 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 <[email protected]> --- arch/x86/include/asm/fpu-internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index e25cc33ec54d..b36f31b18664 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -345,7 +345,7 @@ 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); } -- 1.8.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
