From patchwork Thu Apr 8 18:28:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12192179 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=-26.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 31DA0C43461 for ; Thu, 8 Apr 2021 18:29:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CFB261131 for ; Thu, 8 Apr 2021 18:29:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232844AbhDHS3Q (ORCPT ); Thu, 8 Apr 2021 14:29:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232852AbhDHS3E (ORCPT ); Thu, 8 Apr 2021 14:29:04 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DE41C061764 for ; Thu, 8 Apr 2021 11:28:52 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id q14so2836807ybk.22 for ; Thu, 08 Apr 2021 11:28:52 -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=sqe+SRM2tt54QgMNprHB5Ltl/JmQ4l0M9EfeayUX7cA=; b=prCsiu3tjKJFc4pP0/+ujOO/HtNJYS943pILJiCXrDbIUQY4DwftcDzmjbqU8Znqzs ReSZn865iFbsu11kWjfPBjM/AAiEJpAQQHUMwHxVVAeHXhQN1OHlhomroaYK7Vaim+wi us6bUks8K563fMiSGiRf7cDSFVVRsSPVT9Kp3Y6HKLvXNYAASpNp0uCsZPUmsVI2RO78 7etrNqjlHs2AhheD8vpQrc/1+H0Q9t7QljuufEgx8rL0gFyVyX8i17OaiFy0DvugM8k8 kC3kVB6YoMV5Pfl80tgCca3MJ2B4VTCYyxzgyxEgHMcv4rScjHAd8A0N7P1fnaJc+bQt ykzg== 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=sqe+SRM2tt54QgMNprHB5Ltl/JmQ4l0M9EfeayUX7cA=; b=LHlKNVsrf8qv5dimD9taH8MKH039E6mVCsDKWMA8qcAILLN5QlNsgTx1aYOE9FHhJa qVK2inH4QhJ7eNB7RwwdJeHtuYIidqyqyG6UvZU4uyO0OCl1kP3SeaFVqTLsROkNLTXM is32xis0ToQECEFb5yI3L6lm3BA1m3gTuIV5UwYL8x1SvyZIC1f+M3NJ5Yzy1JSZamZT C0aiwq0D6ivTe2nZ+TURsyBcfPM0DG13MawwQiJ7EPSiTSHeB15wzhU83MMXa6T6yZEw QIWQPOcTCPc5i7wQye/zBqewn1GssE+wcjmzHQmZ6N/9AE3TOOaXd3wS1p4nCjVGCawr CzlQ== X-Gm-Message-State: AOAM533KCYFXck0j8kPxysbvV6q4T2hKhpuSHwJRNglrjn/IL3VV1yAo 0vpN2eg6MspelWSfiqz5oDYP9ebKA7oQezseeYw= X-Google-Smtp-Source: ABdhPJxYVjdCzFadep6CzUxo/2ynBssueHSOvDokbrGpmosVElcDFd+DnNsM/GYXnls1d0LLyuI1Tzej1BjrPfvz2Cw= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:3560:8505:40a2:e021]) (user=samitolvanen job=sendgmr) by 2002:a25:ae03:: with SMTP id a3mr14172639ybj.118.1617906531475; Thu, 08 Apr 2021 11:28:51 -0700 (PDT) Date: Thu, 8 Apr 2021 11:28:28 -0700 In-Reply-To: <20210408182843.1754385-1-samitolvanen@google.com> Message-Id: <20210408182843.1754385-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20210408182843.1754385-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.1.295.g9ea45b61b8-goog Subject: [PATCH v6 03/18] mm: add generic function_nocfi macro From: Sami Tolvanen To: Kees Cook Cc: Nathan Chancellor , Nick Desaulniers , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , "Paul E. McKenney" , Christoph Hellwig , Peter Zijlstra , Sedat Dilek , Mark Rutland , Catalin Marinas , bpf@vger.kernel.org, linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org With CONFIG_CFI_CLANG, the compiler replaces function addresses in instrumented C code with jump table addresses. This means that __pa_symbol(function) returns the physical address of the jump table entry instead of the actual function, which may not work as the jump table code will immediately jump to a virtual address that may not be mapped. To avoid this address space confusion, this change adds a generic definition for function_nocfi(), which architectures that support CFI can override. The typical implementation of would use inline assembly to take the function address, which avoids compiler instrumentation. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Mark Rutland Tested-by: Nathan Chancellor --- include/linux/mm.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 8ba434287387..22cce9c7dd05 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -124,6 +124,16 @@ extern int mmap_rnd_compat_bits __read_mostly; #define lm_alias(x) __va(__pa_symbol(x)) #endif +/* + * With CONFIG_CFI_CLANG, the compiler replaces function addresses in + * instrumented C code with jump table addresses. Architectures that + * support CFI can define this macro to return the actual function address + * when needed. + */ +#ifndef function_nocfi +#define function_nocfi(x) (x) +#endif + /* * To prevent common memory management code establishing * a zero page mapping on a read fault.