From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-13.6 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE,T_DKIMWL_WL_MED, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 9D3DE7D90F for ; Fri, 31 May 2019 15:11:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726902AbfEaPLn (ORCPT ); Fri, 31 May 2019 11:11:43 -0400 Received: from mail-vs1-f73.google.com ([209.85.217.73]:40815 "EHLO mail-vs1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726896AbfEaPLm (ORCPT ); Fri, 31 May 2019 11:11:42 -0400 Received: by mail-vs1-f73.google.com with SMTP id s124so1858876vsb.7 for ; Fri, 31 May 2019 08:11:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=LNEghw4B+GvmCMDyCJlZQOSF0gWgpI6UWg+d86gG2mc=; b=ozkPZplAJd4r//3+vEEoJahNvXQO1X4ZigVyEubSdIpqctPhuNZLdlWXMYpzn67h0X JreDTRTgDzX6i2a85Ia9Q+9zBKklei2FPPQbxVrT8uDoUQNOpsN/p8+BkJ1SU3yDiMNw 1KJBsS9Szx7t+Z3QsoD17P8MBZba3PqICFgjsntr0+BzPLbSbFLUzxrI2rNF4WXbIr6B NjlRCy5ykAL5B1aiDgvaccG0XHNZwMHu3r2aBEaZOLLrreJ9CrY7Ieugpp59+Z5NF2U0 xuVrgPGdqr3vuv5BoBXZKO31zh2+kuZ3KqXUUmM1Uym7mHKx3LiZMdKIk+7MQPDnNV1p ikKw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=LNEghw4B+GvmCMDyCJlZQOSF0gWgpI6UWg+d86gG2mc=; b=ItxvRIX883as4cwelXWrKiMwKaQv9Xz5FhIDL3MCBqgSRGVnKQRsbDgq5INiuYmOuj k2viYfserYK2N0Db3iG5PfRkNIz9x9laV4KUqzcDrT3gUKq2yiKm2mwudL5A7BD5xFP/ Vsw+w5lw4yktOsYiBuTm6CmJA2FO8zdLecDho6TV1MuKE0yOU21sZPuHPTBEcJSl3Y0T YZ/VwaLGmXAKDvph3ijSf/dPPcSYxPZuyNfGY7Jvt6PzbAVHic8G9mEJwfW0L6ZYtggv fXidvk37ktpMqTjXg+NfntQ7/EEtFVSXW0Majm01Pd/7PPyqtIJrebGwYwOTmG8Sc4Dy YnKw== X-Gm-Message-State: APjAAAWXyh8BltfmH9F50Mz0JTAr/65MEWLW8HI5rs8O9uCd63Hp58uj OUpEfOIJqbJcvgQ1JnbVb4B0VbEBMQ== X-Google-Smtp-Source: APXvYqxMRxD/zc6HiE9yfl3teIOaD5ernl+4NfEmJo1Hwn7xZzxHUm1PC8Ix91D9Z/1irN8QwfsHq9covg== X-Received: by 2002:ac5:c215:: with SMTP id m21mr4221628vkk.84.1559315501278; Fri, 31 May 2019 08:11:41 -0700 (PDT) Date: Fri, 31 May 2019 17:08:30 +0200 In-Reply-To: <20190531150828.157832-1-elver@google.com> Message-Id: <20190531150828.157832-3-elver@google.com> Mime-Version: 1.0 References: <20190531150828.157832-1-elver@google.com> X-Mailer: git-send-email 2.22.0.rc1.257.g3120a18244-goog Subject: [PATCH v3 2/3] x86: Use static_cpu_has in uaccess region to avoid instrumentation From: Marco Elver To: peterz@infradead.org, aryabinin@virtuozzo.com, dvyukov@google.com, glider@google.com, andreyknvl@google.com, mark.rutland@arm.com, hpa@zytor.com Cc: corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, arnd@arndb.de, jpoimboe@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kasan-dev@googlegroups.com, Marco Elver Content-Type: text/plain; charset="UTF-8" Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org This patch is a pre-requisite for enabling KASAN bitops instrumentation; using static_cpu_has instead of boot_cpu_has avoids instrumentation of test_bit inside the uaccess region. With instrumentation, the KASAN check would otherwise be flagged by objtool. For consistency, kernel/signal.c was changed to mirror this change, however, is never instrumented with KASAN (currently unsupported under x86 32bit). Signed-off-by: Marco Elver Suggested-by: H. Peter Anvin --- Changes in v3: * Use static_cpu_has instead of moving boot_cpu_has outside uaccess region. Changes in v2: * Replaces patch: 'tools/objtool: add kasan_check_* to uaccess whitelist' --- arch/x86/ia32/ia32_signal.c | 2 +- arch/x86/kernel/signal.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index 629d1ee05599..1cee10091b9f 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -358,7 +358,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, put_user_ex(ptr_to_compat(&frame->uc), &frame->puc); /* Create the ucontext. */ - if (boot_cpu_has(X86_FEATURE_XSAVE)) + if (static_cpu_has(X86_FEATURE_XSAVE)) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 364813cea647..52eb1d551aed 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -391,7 +391,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, put_user_ex(&frame->uc, &frame->puc); /* Create the ucontext. */ - if (boot_cpu_has(X86_FEATURE_XSAVE)) + if (static_cpu_has(X86_FEATURE_XSAVE)) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); -- 2.22.0.rc1.257.g3120a18244-goog