From patchwork Tue Jun 14 06:54:47 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aneesh Kumar K.V" X-Patchwork-Id: 635052 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 3rTLPh10fmz9snm for ; Tue, 14 Jun 2016 17:10:00 +1000 (AEST) Received: from ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3rTLPh042JzDqy0 for ; Tue, 14 Jun 2016 17:10:00 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rTL4t42wRzDqgy for ; Tue, 14 Jun 2016 16:55:26 +1000 (AEST) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u5E6rxHg084061 for ; Tue, 14 Jun 2016 02:55:25 -0400 Received: from e38.co.us.ibm.com (e38.co.us.ibm.com [32.97.110.159]) by mx0a-001b2d01.pphosted.com with ESMTP id 23gf59as31-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 14 Jun 2016 02:55:25 -0400 Received: from localhost by e38.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Tue, 14 Jun 2016 00:55:22 -0600 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: aneesh.kumar@linux.vnet.ibm.com X-IBM-RcptTo: mpe@ellerman.id.au; haokexin@gmail.com; benh@kernel.crashing.org; linuxppc-dev@lists.ozlabs.org; paulus@samba.org Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 1BE6919D803F; Tue, 14 Jun 2016 00:55:01 -0600 (MDT) Received: from b03ledav005.gho.boulder.ibm.com (b03ledav005.gho.boulder.ibm.com [9.17.130.236]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u5E6tLsS41943130; Mon, 13 Jun 2016 23:55:21 -0700 Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6DFA7BE039; Tue, 14 Jun 2016 00:55:21 -0600 (MDT) Received: from skywalker.in.ibm.com (unknown [9.124.35.147]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTP id A9004BE038; Tue, 14 Jun 2016 00:55:19 -0600 (MDT) From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au Subject: [RFC PATCH V1 09/10] powerpc: use jump label for mmu_has_feature Date: Tue, 14 Jun 2016 12:24:47 +0530 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1465887288-12952-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1465887288-12952-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16061406-0028-0000-0000-000004F24C9E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16061406-0029-0000-0000-00002CA2A9BB Message-Id: <1465887288-12952-9-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2016-06-14_03:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1606140077 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Hao , linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K . V" MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Kevin Hao 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 Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/include/asm/mmu.h | 36 ++++++++++++++++++++++++++++++++++++ arch/powerpc/kernel/cputable.c | 17 +++++++++++++++++ arch/powerpc/kernel/setup_32.c | 1 + arch/powerpc/kernel/setup_64.c | 1 + 4 files changed, 55 insertions(+) diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h index c488db09f7a0..e453e095579e 100644 --- a/arch/powerpc/include/asm/mmu.h +++ b/arch/powerpc/include/asm/mmu.h @@ -143,6 +143,41 @@ static inline bool __mmu_has_feature(unsigned long feature) return !!(MMU_FTRS_POSSIBLE & cur_cpu_spec->mmu_features & feature); } +#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 __always_inline bool mmu_has_feature(unsigned long feature) +{ + int i; + + if (!(MMU_FTRS_POSSIBLE & feature)) + return false; + + 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 bool mmu_has_feature(unsigned long feature) { return __mmu_has_feature(feature); @@ -152,6 +187,7 @@ static inline void mmu_clear_feature(unsigned long feature) { cur_cpu_spec->mmu_features &= ~feature; } +#endif /* CONFIG_JUMP_LABEL */ 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 b0a24b425441..a98630183e92 100644 --- a/arch/powerpc/kernel/cputable.c +++ b/arch/powerpc/kernel/cputable.c @@ -2243,4 +2243,21 @@ 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 ac5b41ad94ed..cd0d8814bd9b 100644 --- a/arch/powerpc/kernel/setup_32.c +++ b/arch/powerpc/kernel/setup_32.c @@ -107,6 +107,7 @@ notrace unsigned long __init early_init(unsigned long dt_ptr) */ jump_label_init(); cpu_feat_keys_init(); + mmu_feat_keys_init(); return KERNELBASE + offset; } diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 1bd0d19afe1d..8222950f820f 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -487,6 +487,7 @@ void __init setup_system(void) */ jump_label_init(); cpu_feat_keys_init(); + mmu_feat_keys_init(); /* * Unflatten the device-tree passed by prom_init or kexec