From patchwork Mon Aug 24 11:20:28 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Hao X-Patchwork-Id: 510000 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 5C78A140332 for ; Mon, 24 Aug 2015 21:32:09 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b=nFPZqO5b; dkim-atps=neutral Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 2212D1A2C56 for ; Mon, 24 Aug 2015 21:32:09 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b=nFPZqO5b; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from mail-yk0-x22f.google.com (mail-yk0-x22f.google.com [IPv6:2607:f8b0:4002:c07::22f]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 132141A1DAF for ; Mon, 24 Aug 2015 21:21:09 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b=nFPZqO5b; dkim-atps=neutral Received: by ykll84 with SMTP id l84so130763818ykl.0 for ; Mon, 24 Aug 2015 04:21:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=K6K5CWwFq7CseOO7fTFTbplFdtZtNUeRJosNjfZ/Ev4=; b=nFPZqO5bXYaDTBXCD9VO4jUbr5ox44SfnIvpQWFwYcUw3BR+LKpSQ3mB5XE32mBWL2 T4JEyKYKLGA0rabdYPfZo8/nlHEQkWgLof+eHvbwX/Zsqr+tz2RP0MY52QnHPYjr+pEo lRMSLeXNoADMMx1i0wIVQtPhTvkIJx4eKGSZ1ke/kNX46EcRFow0OpwfcEZUAZ8gwPF2 8R2ARemJhG5FmamArIu1UJCpHJeDxrEMpl7yYFl7o64swBOuAWPXR0lNmWhxkP8n7HWT OwyHHTkZePkQqkk2azNgqwu1A65oRpZt/FNWa6ug+4+h1KMthICKUppDCoI/d1TWh02R AnCA== X-Received: by 10.13.212.207 with SMTP id w198mr28501148ywd.68.1440415267077; Mon, 24 Aug 2015 04:21:07 -0700 (PDT) Received: from pek-khao-d1.corp.ad.wrs.com (unknown-178-22.windriver.com. [147.11.178.22]) by smtp.gmail.com with ESMTPSA id i82sm9014125ywg.1.2015.08.24.04.21.03 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Aug 2015 04:21:06 -0700 (PDT) From: Kevin Hao To: Michael Ellerman Subject: [PATCH v2 6/6] powerpc: use jump label for mmu_has_feature Date: Mon, 24 Aug 2015 19:20:28 +0800 Message-Id: <1440415228-8006-7-git-send-email-haokexin@gmail.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1440415228-8006-1-git-send-email-haokexin@gmail.com> References: <1440415228-8006-1-git-send-email-haokexin@gmail.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Zijlstra , linuxppc-dev@lists.ozlabs.org, Ingo Molnar , linux-kernel@vger.kernel.org MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" The mmu features are fixed once the probe of mmu features are done. And the function mmu_has_feature() does be used in some hot path. The checking of the mmu features for each time of invoking of mmu_has_feature() seems suboptimal. This tries to reduce this overhead of this check by using jump label. The generated assemble code of the following c program: if (mmu_has_feature(MMU_FTR_XXX)) xxx() Before: lis r9,-16230 lwz r9,12324(r9) lwz r9,24(r9) andi. r10,r9,16 beqlr+ After: nop if MMU_FTR_XXX is enabled b xxx if MMU_FTR_XXX is not enabled Signed-off-by: Kevin Hao --- v2: Use the open-coded definition and initialization for mmu_feat_keys[]. arch/powerpc/include/asm/mmu.h | 29 +++++++++++++++++++++++++++++ arch/powerpc/kernel/cputable.c | 17 +++++++++++++++++ arch/powerpc/kernel/setup_32.c | 1 + arch/powerpc/kernel/setup_64.c | 1 + 4 files changed, 48 insertions(+) diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h index 3d5abfe6ba67..e091de352a75 100644 --- a/arch/powerpc/include/asm/mmu.h +++ b/arch/powerpc/include/asm/mmu.h @@ -109,6 +109,34 @@ DECLARE_PER_CPU(int, next_tlbcam_idx); #endif +#ifdef CONFIG_JUMP_LABEL +#include + +#define MAX_MMU_FEATURES (8 * sizeof(((struct cpu_spec *)0)->mmu_features)) + +extern struct static_key_true mmu_feat_keys[MAX_MMU_FEATURES]; + +extern void mmu_feat_keys_init(void); + +static inline int mmu_has_feature(unsigned long feature) +{ + int i; + + i = __builtin_ctzl(feature); + return static_branch_likely(&mmu_feat_keys[i]); +} + +static inline void mmu_clear_feature(unsigned long feature) +{ + int i; + + i = __builtin_ctzl(feature); + cur_cpu_spec->mmu_features &= ~feature; + static_branch_disable(&mmu_feat_keys[i]); +} +#else +static inline void mmu_feat_keys_init(void) { } + static inline int mmu_has_feature(unsigned long feature) { return (cur_cpu_spec->mmu_features & feature); @@ -118,6 +146,7 @@ static inline void mmu_clear_feature(unsigned long feature) { cur_cpu_spec->mmu_features &= ~feature; } +#endif extern unsigned int __start___mmu_ftr_fixup, __stop___mmu_ftr_fixup; diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c index ea94931c5e70..6b505c98520b 100644 --- a/arch/powerpc/kernel/cputable.c +++ b/arch/powerpc/kernel/cputable.c @@ -2214,4 +2214,21 @@ void __init cpu_feat_keys_init(void) static_branch_disable(&cpu_feat_keys[i]); } } + +struct static_key_true mmu_feat_keys[MAX_MMU_FEATURES] = { + [0 ... MAX_MMU_FEATURES - 1] = STATIC_KEY_TRUE_INIT +}; +EXPORT_SYMBOL_GPL(mmu_feat_keys); + +void __init mmu_feat_keys_init(void) +{ + int i; + + for (i = 0; i < MAX_MMU_FEATURES; i++) { + unsigned long f = 1ul << i; + + if (!(cur_cpu_spec->mmu_features & f)) + static_branch_disable(&mmu_feat_keys[i]); + } +} #endif diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c index 93756175a13c..8acff5a4bc3e 100644 --- a/arch/powerpc/kernel/setup_32.c +++ b/arch/powerpc/kernel/setup_32.c @@ -116,6 +116,7 @@ notrace void __init machine_init(u64 dt_ptr) jump_label_init(); cpu_feat_keys_init(); + mmu_feat_keys_init(); /* Enable early debugging if any specified (see udbg.h) */ udbg_early_init(); diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 4cf3894d91fa..df6f98f1c46c 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -252,6 +252,7 @@ void __init early_setup(unsigned long dt_ptr) jump_label_init(); cpu_feat_keys_init(); + mmu_feat_keys_init(); /* -------- printk is now safe to use ------- */