From patchwork Thu Apr 1 23:32:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12179925 X-Patchwork-Delegate: kuba@kernel.org 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=-26.3 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=unavailable 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 0432BC43460 for ; Thu, 1 Apr 2021 23:32:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8CCF61108 for ; Thu, 1 Apr 2021 23:32:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236199AbhDAXcl (ORCPT ); Thu, 1 Apr 2021 19:32:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235984AbhDAXc0 (ORCPT ); Thu, 1 Apr 2021 19:32:26 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B1D3C0613E6 for ; Thu, 1 Apr 2021 16:32:25 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id w9so7493908ybw.7 for ; Thu, 01 Apr 2021 16:32:25 -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=MkcfzR92H2jDmq2d4RL+VoRfm9LM05H88oYR/VzcB5I=; b=Rkz+baugCU0boZ02HoTqlKubiEntpTT9QoWd+o+BAtncvl/retLEsZJAVH1rB01pBf 9MWWF5Ch6NCgBFjhkYOnIyGZkaUHAm4WQipSnmL1TN8jSdE1KnFkhrDGOdtJwAMKUq7Y ICnqrEyN5y2FKL4wdgElMDjDKvF3tSZHAaNz5+nfb285KADVJhqWX3UYzFsXrMf6/kld bJQuBvFO6EnQ41XejqN7DiVAEPNg1FbXVySMSbcg8voHCyEIDpyF5ZrhRYBVPedQE8xQ qcVp8YZPEw+NmZ9Yi0mzjnmQy7xzaJDg/OgCMdv++swJ3YMIgKApL8IVshi8YNvR0HJb NrrQ== 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=MkcfzR92H2jDmq2d4RL+VoRfm9LM05H88oYR/VzcB5I=; b=lizCeqLWwiUbLVYZ2yiSiqP5WhuI8HuSiiNG51InsrSirfoFD8q7oC4VgxOeUIr0cP kjiMhdri9OmjI2+q9aedD0rS/slOPTpitTQCdDxq8p5JY2UOupZp6W5piKZIk+S1e6H9 n8g1zaZeX1/UB5uk2h4IMGu84NoJnG6TbJfPhM1PyRfrz8eJUv0MlXUSTHzcNxfnULnX OhKFoAW31r5IOWUTvKGa+dcCyh64SDynGSoCzWfCgJIIqVNCX6AoCI8FU2kRmH9YYRzC VF+sxNEmqoWPIr92faw8Rodni9UZpFgxzDwm8dWs0CgznzlMI2yx7pb/osKZquUisGtF n86Q== X-Gm-Message-State: AOAM532OH1lp8ycCthsm2biwD6pCl0+SAfNAMq42JsdnA1fkn4AXz0Yv m3slUWBjdzyin4CT3QG2BzI5+eZBjoLpCQiyFAU= X-Google-Smtp-Source: ABdhPJxZYcMHvWjMRQqjhTv5hlYtkLPcoAOWWHLVSo1F+sDIZa5GooWGPiUDl1KsIBupRPE2wPS+ZDp0ie617LFUrGg= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:4cd1:da86:e91b:70b4]) (user=samitolvanen job=sendgmr) by 2002:a25:d045:: with SMTP id h66mr15244938ybg.138.1617319944327; Thu, 01 Apr 2021 16:32:24 -0700 (PDT) Date: Thu, 1 Apr 2021 16:32:01 -0700 In-Reply-To: <20210401233216.2540591-1-samitolvanen@google.com> Message-Id: <20210401233216.2540591-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20210401233216.2540591-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.0.208.g409f899ff0-goog Subject: [PATCH v5 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: bpf@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: Christoph Hellwig Acked-by: Mark Rutland --- 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.