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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 03900C433DF for ; Wed, 14 Oct 2020 21:26:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A4A222258 for ; Wed, 14 Oct 2020 21:26:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730816AbgJNV0g (ORCPT ); Wed, 14 Oct 2020 17:26:36 -0400 Received: from mail-io1-f65.google.com ([209.85.166.65]:34855 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726484AbgJNV0f (ORCPT ); Wed, 14 Oct 2020 17:26:35 -0400 Received: by mail-io1-f65.google.com with SMTP id k6so1254610ior.2 for ; Wed, 14 Oct 2020 14:26:33 -0700 (PDT) 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:mime-version :content-transfer-encoding; bh=O1nywZUMtAWTHD6N03tdA5btMKZB3dhRS89gnTJeMJo=; b=KZ2pjUkV+seB0JILjZmUh7HktJ1A66VuS3Gter/MM35Wd1HYumXo/c1GEpJ+bomGLu wtLf5BWhlT2CLa09GSWCLXICZWxc9/xlRUnZMKJbOzsRZOe/6QR2G/kafCP63C41eaSc Qf6LfoJcFpkQwCurTbHggHPzx/hXBjXyvL6TYqeXhG8xCpQOwjqqwebXpYzfGyuZJAXU t10+K2MA1OZ11QI+lOk/mZRkb+CSS3z/GKwCgEJqWOe3O8E1bLrm3bqLnjuoA7h4MqCF vnCHfpbWVVqNcJHUr02F2i/+kL1KAJXTbo0/cdl/QPDvlBGxCn20qIcpOEbwvrb+C/g2 CBSA== X-Gm-Message-State: AOAM531LSwelSwUQNRL7qXJp7C0e7xsCaeGNpbn6LoCcJMAhy9KKovit Vh7X61hdXNfB8PaGGkTGXh5sLPPefm5Eiw== X-Google-Smtp-Source: ABdhPJzruVG3pSCEWcOrxnh6090AyBJ5NxVNzPMH+gyorbBMqKTMWcoYK+khXH2X3yS4nNEG9Dbe5Q== X-Received: by 2002:a6b:6001:: with SMTP id r1mr1040527iog.29.1602710793012; Wed, 14 Oct 2020 14:26:33 -0700 (PDT) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id z15sm734385ioj.22.2020.10.14.14.26.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Oct 2020 14:26:32 -0700 (PDT) From: Arvind Sankar To: Nathan Chancellor , Nick Desaulniers , clang-built-linux@googlegroups.com Cc: linux-kernel@vger.kernel.org Subject: [PATCH] compiler.h: Fix barrier_data() on clang Date: Wed, 14 Oct 2020 17:26:31 -0400 Message-Id: <20201014212631.207844-1-nivedita@alum.mit.edu> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") neglected to copy barrier_data() from compiler-gcc.h into compiler-clang.h. The definition in compiler-gcc.h was really to work around clang's more aggressive optimization, so this broke barrier_data() on clang, and consequently memzero_explicit() as well. For example, this results in at least the memzero_explicit() call in lib/crypto/sha256.c:sha256_transform() being optimized away by clang. Fix this by moving the definition of barrier_data() into compiler.h. Also move the gcc/clang definition of barrier() into compiler.h, __memory_barrier() is icc-specific (and barrier() is already defined using it in compiler-intel.h) and doesn't belong in compiler.h. Signed-off-by: Arvind Sankar Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") --- include/linux/compiler-clang.h | 6 ------ include/linux/compiler-gcc.h | 19 ------------------- include/linux/compiler.h | 18 ++++++++++++++++-- 3 files changed, 16 insertions(+), 27 deletions(-) diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index cee0c728d39a..04c0a5a717f7 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -52,12 +52,6 @@ #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 #endif -/* The following are for compatibility with GCC, from compiler-gcc.h, - * and may be redefined here because they should not be shared with other - * compilers, like ICC. - */ -#define barrier() __asm__ __volatile__("" : : : "memory") - #if __has_feature(shadow_call_stack) # define __noscs __attribute__((__no_sanitize__("shadow-call-stack"))) #endif diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 7a3769040d7d..fda30ffb037b 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -15,25 +15,6 @@ # error Sorry, your compiler is too old - please upgrade it. #endif -/* Optimization barrier */ - -/* The "volatile" is due to gcc bugs */ -#define barrier() __asm__ __volatile__("": : :"memory") -/* - * This version is i.e. to prevent dead stores elimination on @ptr - * where gcc and llvm may behave differently when otherwise using - * normal barrier(): while gcc behavior gets along with a normal - * barrier(), llvm needs an explicit input variable to be assumed - * clobbered. The issue is as follows: while the inline asm might - * access any memory it wants, the compiler could have fit all of - * @ptr into memory registers instead, and since @ptr never escaped - * from that, it proved that the inline asm wasn't touching any of - * it. This version works well with both compilers, i.e. we're telling - * the compiler that the inline asm absolutely may see the contents - * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 - */ -#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") - /* * This macro obfuscates arithmetic on a variable address so that gcc * shouldn't recognize the original var, and make assumptions about it. diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 92ef163a7479..dfba70b2644f 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -80,11 +80,25 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, /* Optimization barrier */ #ifndef barrier -# define barrier() __memory_barrier() +/* The "volatile" is due to gcc bugs */ +# define barrier() __asm__ __volatile__("": : :"memory") #endif #ifndef barrier_data -# define barrier_data(ptr) barrier() +/* + * This version is i.e. to prevent dead stores elimination on @ptr + * where gcc and llvm may behave differently when otherwise using + * normal barrier(): while gcc behavior gets along with a normal + * barrier(), llvm needs an explicit input variable to be assumed + * clobbered. The issue is as follows: while the inline asm might + * access any memory it wants, the compiler could have fit all of + * @ptr into memory registers instead, and since @ptr never escaped + * from that, it proved that the inline asm wasn't touching any of + * it. This version works well with both compilers, i.e. we're telling + * the compiler that the inline asm absolutely may see the contents + * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 + */ +# define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") #endif /* workaround for GCC PR82365 if needed */ -- 2.26.2