From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id IQvNL1uZHVscEAAAmS7hNA ; Sun, 10 Jun 2018 21:35:33 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 9155360791; Sun, 10 Jun 2018 21:35:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.4 required=2.0 tests=BAYES_00,DATE_IN_PAST_06_12, MAILING_LIST_MULTI autolearn=no autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 0E01F604D4; Sun, 10 Jun 2018 21:35:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0E01F604D4 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=vmware.com Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753762AbeFJVfb (ORCPT + 21 others); Sun, 10 Jun 2018 17:35:31 -0400 Received: from ex13-edg-ou-001.vmware.com ([208.91.0.189]:16964 "EHLO EX13-EDG-OU-001.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753531AbeFJVeI (ORCPT ); Sun, 10 Jun 2018 17:34:08 -0400 Received: from sc9-mailhost3.vmware.com (10.113.161.73) by EX13-EDG-OU-001.vmware.com (10.113.208.155) with Microsoft SMTP Server id 15.0.1156.6; Sun, 10 Jun 2018 14:33:44 -0700 Received: from sc2-haas01-esx0118.eng.vmware.com (sc2-haas01-esx0118.eng.vmware.com [10.172.44.118]) by sc9-mailhost3.vmware.com (Postfix) with ESMTP id 0F4CA406D6; Sun, 10 Jun 2018 14:34:06 -0700 (PDT) From: Nadav Amit To: , CC: Nadav Amit , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Josh Poimboeuf Subject: [PATCH v3 4/9] x86: alternatives: macrofy locks for better inlining Date: Sun, 10 Jun 2018 07:19:06 -0700 Message-ID: <20180610141911.52948-5-namit@vmware.com> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180610141911.52948-1-namit@vmware.com> References: <20180610141911.52948-1-namit@vmware.com> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: None (EX13-EDG-OU-001.vmware.com: namit@vmware.com does not designate permitted sender hosts) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org GCC considers the number of statements in inlined assembly blocks, according to new-lines and semicolons, as an indication to the cost of the block in time and space. This data is distorted by the kernel code, which puts information in alternative sections. As a result, the compiler may perform incorrect inlining and branch optimizations. The solution is to set an assembly macro and call it from the inlined assembly block. As a result GCC considers the inline assembly block as a single instruction. This patch handles the LOCK prefix, allowing more aggresive inlining. text data bss dec hex filename 18140140 10225284 2957312 31322736 1ddf270 ./vmlinux before 18146889 10225380 2957312 31329581 1de0d2d ./vmlinux after (+6845) Static text symbols: Before: 40286 After: 40218 (-68) Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: Josh Poimboeuf Signed-off-by: Nadav Amit --- arch/x86/include/asm/alternative-asm.h | 20 ++++++++++++++------ arch/x86/include/asm/alternative.h | 11 ++--------- arch/x86/kernel/macros.S | 1 + 3 files changed, 17 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h index 31b627b43a8e..8e4ea39e55d0 100644 --- a/arch/x86/include/asm/alternative-asm.h +++ b/arch/x86/include/asm/alternative-asm.h @@ -7,16 +7,24 @@ #include #ifdef CONFIG_SMP - .macro LOCK_PREFIX -672: lock +.macro LOCK_PREFIX_HERE .pushsection .smp_locks,"a" .balign 4 - .long 672b - . + .long 671f - . # offset .popsection - .endm +671: +.endm + +.macro LOCK_PREFIX insn:vararg + LOCK_PREFIX_HERE + lock \insn +.endm #else - .macro LOCK_PREFIX - .endm +.macro LOCK_PREFIX_HERE +.endm + +.macro LOCK_PREFIX insn:vararg +.endm #endif /* diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 4cd6a3b71824..d7faa16622d8 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -31,15 +31,8 @@ */ #ifdef CONFIG_SMP -#define LOCK_PREFIX_HERE \ - ".pushsection .smp_locks,\"a\"\n" \ - ".balign 4\n" \ - ".long 671f - .\n" /* offset */ \ - ".popsection\n" \ - "671:" - -#define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; " - +#define LOCK_PREFIX_HERE "LOCK_PREFIX_HERE\n\t" +#define LOCK_PREFIX "LOCK_PREFIX " #else /* ! CONFIG_SMP */ #define LOCK_PREFIX_HERE "" #define LOCK_PREFIX "" diff --git a/arch/x86/kernel/macros.S b/arch/x86/kernel/macros.S index f1fe1d570365..852487a9fc56 100644 --- a/arch/x86/kernel/macros.S +++ b/arch/x86/kernel/macros.S @@ -8,3 +8,4 @@ #include #include +#include -- 2.17.0