From patchwork Sun Jul 14 09:02:05 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Hao X-Patchwork-Id: 258893 X-Patchwork-Delegate: benh@kernel.crashing.org Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [IPv6:::1]) by ozlabs.org (Postfix) with ESMTP id CC9D12C0149 for ; Sun, 14 Jul 2013 19:09:33 +1000 (EST) Received: from mail.windriver.com (mail.windriver.com [147.11.1.11]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mail.windriver.com", Issuer "Intel External Basic Issuing CA 3A" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 997EA2C00F3 for ; Sun, 14 Jul 2013 19:07:33 +1000 (EST) Received: from ALA-HCA.corp.ad.wrs.com (ala-hca.corp.ad.wrs.com [147.11.189.40]) by mail.windriver.com (8.14.5/8.14.3) with ESMTP id r6E97URn027283 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL); Sun, 14 Jul 2013 02:07:30 -0700 (PDT) Received: from pek-khao-d1.corp.ad.wrs.com (128.224.162.196) by ALA-HCA.corp.ad.wrs.com (147.11.189.50) with Microsoft SMTP Server id 14.2.342.3; Sun, 14 Jul 2013 02:07:29 -0700 From: Kevin Hao To: Benjamin Herrenschmidt Subject: [PATCH 3/4] powerpc: make flush_fp_to_thread() nop when CONFIG_PPC_FPU is disabled Date: Sun, 14 Jul 2013 17:02:05 +0800 Message-ID: <1373792526-16241-4-git-send-email-haokexin@gmail.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1373792526-16241-1-git-send-email-haokexin@gmail.com> References: <1373792526-16241-1-git-send-email-haokexin@gmail.com> MIME-Version: 1.0 Cc: linuxppc X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" In the current kernel, the function flush_fp_to_thread() is not dependent on CONFIG_PPC_FPU. So most invocations of this function is not wrapped by CONFIG_PPC_FPU. Even through we don't really save the FPRs to the thread struct if CONFIG_PPC_FPU is not enabled, but there does have some runtime overhead such as the check for tsk->thread.regs and preempt disable and enable. It really make no sense to do that. So make it a nop when CONFIG_PPC_FPU is disabled. Also remove the wrapped #ifdef CONFIG_PPC_FPU when invoking this function. Signed-off-by: Kevin Hao --- arch/powerpc/include/asm/switch_to.h | 7 ++++++- arch/powerpc/kernel/process.c | 2 ++ arch/powerpc/math-emu/math.c | 3 +-- 3 files changed, 9 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h index 33e1cd8..39cf0f6 100644 --- a/arch/powerpc/include/asm/switch_to.h +++ b/arch/powerpc/include/asm/switch_to.h @@ -19,7 +19,6 @@ extern struct task_struct *_switch(struct thread_struct *prev, extern void giveup_fpu(struct task_struct *); extern void load_up_fpu(void); extern void enable_kernel_fp(void); -extern void flush_fp_to_thread(struct task_struct *); extern void enable_kernel_altivec(void); extern void load_up_altivec(struct task_struct *); extern int emulate_altivec(struct pt_regs *); @@ -37,6 +36,12 @@ static inline void discard_lazy_cpu_state(void) } #endif +#ifdef CONFIG_PPC_FPU +extern void flush_fp_to_thread(struct task_struct *); +#else +static inline void flush_fp_to_thread(struct task_struct *t) { } +#endif + #ifdef CONFIG_ALTIVEC extern void flush_altivec_to_thread(struct task_struct *); extern void giveup_altivec(struct task_struct *); diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index c517dbe..0ec255a 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -74,6 +74,7 @@ struct task_struct *last_task_used_vsx = NULL; struct task_struct *last_task_used_spe = NULL; #endif +#ifdef CONFIG_PPC_FPU /* * Make sure the floating-point register state in the * the thread_struct is up to date for task tsk. @@ -107,6 +108,7 @@ void flush_fp_to_thread(struct task_struct *tsk) } } EXPORT_SYMBOL_GPL(flush_fp_to_thread); +#endif void enable_kernel_fp(void) { diff --git a/arch/powerpc/math-emu/math.c b/arch/powerpc/math-emu/math.c index f9ef347..d1ebac7 100644 --- a/arch/powerpc/math-emu/math.c +++ b/arch/powerpc/math-emu/math.c @@ -7,6 +7,7 @@ #include #include +#include #include #include @@ -425,9 +426,7 @@ do_mathemu(struct pt_regs *regs) * is flushed into the thread_struct before attempting * emulation */ -#ifdef CONFIG_PPC_FPU flush_fp_to_thread(current); -#endif eflag = func(op0, op1, op2, op3);