From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>, Fenghua Yu <fenghua.yu@intel.com>,
Oleg Nesterov <oleg@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
yu-cheng yu <yu-cheng.yu@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Rik van Riel <riel@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly
Date: Fri, 22 Jan 2016 16:56:05 -0800 [thread overview]
Message-ID: <93f2a482fce2ac1815d324344d03ff26ceabe439.1453510332.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1453510332.git.luto@kernel.org>
In-Reply-To: <cover.1453510332.git.luto@kernel.org>
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..183b300f6a8b 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 (!cpu_has_fpu && (read_cr0() & X86_CR0_EM)) {
struct math_emu_info info = { };
conditional_sti(regs);
--
2.5.0
next prev parent reply other threads:[~2016-01-23 0:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-23 0:56 [PATCH 0/5] x86/fpu: eagerfpu fixes, speedups, and default enablement Andy Lutomirski
2016-01-23 0:56 ` [PATCH 1/5] x86/fpu: Fix math emulation in eager fpu mode Andy Lutomirski
2016-01-23 10:02 ` Borislav Petkov
2016-01-23 17:40 ` Andy Lutomirski
2016-01-23 17:51 ` Borislav Petkov
2016-01-23 0:56 ` [PATCH 2/5] x86/fpu: Fix FNSAVE usage in eagerfpu mode Andy Lutomirski
2016-01-23 0:56 ` [PATCH 3/5] x86/fpu: Fold fpu_copy into fpu__copy Andy Lutomirski
2016-01-23 0:56 ` Andy Lutomirski [this message]
2016-01-23 10:14 ` [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly Borislav Petkov
2016-01-23 22:09 ` Andy Lutomirski
2016-01-23 23:35 ` Borislav Petkov
2016-01-23 0:56 ` [PATCH 5/5] x86/fpu: Default eagerfpu=on on all CPUs Andy Lutomirski
2016-01-23 10:19 ` Borislav Petkov
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