From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F1EAC2D0A8 for ; Mon, 28 Sep 2020 12:45:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 58DD722262 for ; Mon, 28 Sep 2020 12:45:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="uCS0qWvu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726559AbgI1MpI (ORCPT ); Mon, 28 Sep 2020 08:45:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52136 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726393AbgI1MpH (ORCPT ); Mon, 28 Sep 2020 08:45:07 -0400 Received: from mail-ej1-x643.google.com (mail-ej1-x643.google.com [IPv6:2a00:1450:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 795F7C061755; Mon, 28 Sep 2020 05:45:07 -0700 (PDT) Received: by mail-ej1-x643.google.com with SMTP id i26so8246190ejb.12; Mon, 28 Sep 2020 05:45:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=eDbNGoXjUOxyTq/2/7gQ4AH74xLZ8mTu0ngi+MaAE+k=; b=uCS0qWvuD09wigPlBYfAAAyoZyfjUT2Xc99XxqOxnCIlYvflGWoHp0ftk6mZH5d/uT 3Q5APB8NEVGPO20LVhDzCsYjZACyTTRbVfXtTp9ttdpHA+8P+WIwl0wBdAQXlumqmfid prEWKXdYRBu6R2rDyNiN+EM4Whl6dk3xbOhxSvs2rmI2rzxjo1EbwIWjgPhmmwS0SDhz NjYspqFgLLmxjrijp5cYue/6BehuzCNHBInqzGbbw46DaPO+BPYv6kotgwRBQPGQ8uFw I7YROKBUhceRMTsDZHCKtWzjjmQ8/Rcz8scWhZCYqgg01BbE8tCpTZ0J217sajEvMiUt 8DDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=eDbNGoXjUOxyTq/2/7gQ4AH74xLZ8mTu0ngi+MaAE+k=; b=eA0QukvaPZ9dK6D52lS6yQyDsca2QDby1+1CVYz2L+FeGbBUIJ0Q23sBvvP57wIvbT h6AD5JYvvfZ05hnik7gxVqWKoPrtFkhqkcy2xGJQaks5FA466p2osaNlpEb3wL4GPy6z qfjd0+2bunMFeLXMzH3wJH2cMg9lBKvMbGeU3yCqunJfkpyVqrP4oxm843tuQXK5PUVK hATjtZl34lh6ziVcYXXAFsXNuYxc861zZeacR/m+obNCujZjumPQ/isSDQ9h86WMvhJC vjZpwKJJqVf4yXi0W17cYiygSvlGvM4qRi/bqVOUnM/9aNyqsMlYycsbs0I/0vFS6WLR 3Vhg== X-Gm-Message-State: AOAM533quDL6444zjz3J6OniXf9b6thhop+CYes023yvxk7h9hHO+sm7 QtNJ3jps92eLdesXeo3toZ8= X-Google-Smtp-Source: ABdhPJwrcAeGcgwC0x4c6zDkB9w6jAFa372e6W6yiAT/BrBcUqZaC6/RpiOAZ9gQGwQKzlOFDOyv0w== X-Received: by 2002:a17:906:1192:: with SMTP id n18mr1527579eja.515.1601297106102; Mon, 28 Sep 2020 05:45:06 -0700 (PDT) Received: from felia.fritz.box ([2001:16b8:2d9d:5000:7872:7299:adfa:b749]) by smtp.gmail.com with ESMTPSA id m4sm1589214ede.70.2020.09.28.05.45.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2020 05:45:05 -0700 (PDT) From: Lukas Bulwahn To: Balbir Singh , Thomas Gleixner Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Nathan Chancellor , Nick Desaulniers , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, kernel-janitors@vger.kernel.org, linux-safety@lists.elisa.tech, Lukas Bulwahn Subject: [PATCH -next for tip:x86/pti] x86/tlb: drop unneeded local vars in enable_l1d_flush_for_task() Date: Mon, 28 Sep 2020 14:44:57 +0200 Message-Id: <20200928124457.27289-1-lukas.bulwahn@gmail.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit b6724f118d44 ("prctl: Hook L1D flushing in via prctl") checks the validity for enable_l1d_flush_for_task() and introduces some superfluous local variables for that implementation. make clang-analyzer on x86_64 tinyconfig caught my attention with: arch/x86/mm/tlb.c:332:2: warning: Value stored to 'cpu' is never read \ [clang-analyzer-deadcode.DeadStores] Compilers will detect these superfluous local variables and assignment and optimize this anyway. So, the resulting binary is identical before and after this change. Simplify the code and remove superfluous local variables to make clang-analyzer happy. No functional change. No change in binary with supported compilers. Signed-off-by: Lukas Bulwahn --- applies cleanly on next-20200925 Balbir, please review and ack. Thomas, please pick this minor non-urgent clean-up patch into the x86/pti branch of tip as follow-up to: https://lore.kernel.org/lkml/160026187842.15536.285514864386042510.tip-bot2@tip-bot2/ I quickly confirmed that the binary did not change with this change to the source code; The hash of tlb.o remained the same before and after the change. So, in my setup: md5sum tlb.o 7c7e096bab0fd87bd2c8437d8c7dc3fa tlb.o linux-safety, please verify and validate this change. arch/x86/mm/tlb.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 6b0f4c88b07c..90515c04d90a 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -316,7 +316,7 @@ EXPORT_SYMBOL_GPL(leave_mm); int enable_l1d_flush_for_task(struct task_struct *tsk) { - int cpu, ret = 0, i; + int i; /* * Do not enable L1D_FLUSH_OUT if @@ -329,7 +329,7 @@ int enable_l1d_flush_for_task(struct task_struct *tsk) !static_cpu_has(X86_FEATURE_FLUSH_L1D)) return -EINVAL; - cpu = get_cpu(); + get_cpu(); for_each_cpu(i, &tsk->cpus_mask) { if (cpu_data(i).smt_active == true) { @@ -340,7 +340,7 @@ int enable_l1d_flush_for_task(struct task_struct *tsk) set_ti_thread_flag(&tsk->thread_info, TIF_SPEC_L1D_FLUSH); put_cpu(); - return ret; + return 0; } int disable_l1d_flush_for_task(struct task_struct *tsk) -- 2.17.1