[PATCH v2 4/5] x86/fpu: Speed up lazy FPU restores slightly

From	Andy Lutomirski <luto@kernel.org>
Newsgroups	linux.kernel
Subject	[PATCH v2 4/5] x86/fpu: Speed up lazy FPU restores slightly
Date	2016-01-24 23:40 +0100
Message-ID	<qUBuc-2ZJ-65@gated-at.bofh.it> (permalink)
References	<qUBua-2ZJ-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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If we have an FPU, there's no need to check CR0 for FPU emulation.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/kernel/traps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 87f80febf477..36a9c017540e 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -752,7 +752,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
 	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
 
 #ifdef CONFIG_MATH_EMULATION
-	if (read_cr0() & X86_CR0_EM) {
+	if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
 		struct math_emu_info info = { };
 
 		conditional_sti(regs);
-- 
2.5.0

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[PATCH v2 4/5] x86/fpu: Speed up lazy FPU restores slightly Andy Lutomirski <luto@kernel.org> - 2016-01-24 23:40 +0100

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