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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 52CB1C43381 for ; Thu, 18 Mar 2021 22:31:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 32A5064F6D for ; Thu, 18 Mar 2021 22:31:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232096AbhCRWa3 (ORCPT ); Thu, 18 Mar 2021 18:30:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231886AbhCRW36 (ORCPT ); Thu, 18 Mar 2021 18:29:58 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F1A1C06174A; Thu, 18 Mar 2021 15:29:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Cn4bXM9HxhAlrOZ3Mbplt0GOUw7Lo+j1yUk2kct+Irs=; b=tNw6kldUBrU7pqrjsLTuiJ45wH J5nqlqtTWC4KIeNEZkXHhn7telPcGKx2sM6vLzM9FRRkkUjUnUh7ci/PfRjLF2U5J7BdGzfEagJ3i re9fr2El7gw5HNl6tyYb7sz+jXmRJBfRlNTC6ruofJxKCVB91r/5bx3e/1voUzC8pyuUOdDvigLyA 1SfSXKG5C4RyzVgUyV+QTy+3a4aTLA/8LFQ1+bpSQlPbIYwiAcHsl/wyBGaqmz7EFiYPA3a/Oot43 XhLv2bRb9esgYJZp1Yp2glHHmY/vLgmxgE2id4a3WqU/Aqeyd6bOcjDD2JjmIBiZLdMGLnY7M7Uml 09ZyGx3Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lN18i-003Z72-Lm; Thu, 18 Mar 2021 22:29:26 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5A1EF3006E0; Thu, 18 Mar 2021 23:29:11 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 353FC23D18406; Thu, 18 Mar 2021 23:29:11 +0100 (CET) Date: Thu, 18 Mar 2021 23:29:10 +0100 From: Peter Zijlstra To: Sami Tolvanen Cc: Kees Cook , Nathan Chancellor , Nick Desaulniers , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , "Paul E. McKenney" , Christoph Hellwig , 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 Subject: Re: [PATCH v2 01/17] add support for Clang CFI Message-ID: References: <20210318171111.706303-1-samitolvanen@google.com> <20210318171111.706303-2-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210318171111.706303-2-samitolvanen@google.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Mar 18, 2021 at 10:10:55AM -0700, Sami Tolvanen wrote: > +static void update_shadow(struct module *mod, unsigned long base_addr, > + update_shadow_fn fn) > +{ > + struct cfi_shadow *prev; > + struct cfi_shadow *next; > + unsigned long min_addr, max_addr; > + > + next = vmalloc(SHADOW_SIZE); > + > + mutex_lock(&shadow_update_lock); > + prev = rcu_dereference_protected(cfi_shadow, > + mutex_is_locked(&shadow_update_lock)); > + > + if (next) { > + next->base = base_addr >> PAGE_SHIFT; > + prepare_next_shadow(prev, next); > + > + min_addr = (unsigned long)mod->core_layout.base; > + max_addr = min_addr + mod->core_layout.text_size; > + fn(next, mod, min_addr & PAGE_MASK, max_addr & PAGE_MASK); > + > + set_memory_ro((unsigned long)next, SHADOW_PAGES); > + } > + > + rcu_assign_pointer(cfi_shadow, next); > + mutex_unlock(&shadow_update_lock); > + synchronize_rcu_expedited(); expedited is BAD(tm), why is it required and why doesn't it have a comment? > + > + if (prev) { > + set_memory_rw((unsigned long)prev, SHADOW_PAGES); > + vfree(prev); > + } > +}