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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 A38BEC34047 for ; Wed, 19 Feb 2020 17:20:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7008320801 for ; Wed, 19 Feb 2020 17:20:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="KFt4lYhl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726712AbgBSRUl (ORCPT ); Wed, 19 Feb 2020 12:20:41 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:39474 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726558AbgBSRUl (ORCPT ); Wed, 19 Feb 2020 12:20:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=QTd8tp07eNhPjbukKA+LEnzzWa9t43kN5uiLpBUNZb0=; b=KFt4lYhlQgjwiExZP6P3uJQ+Kt CTuZ71CrDD++r8agKV/9Ljd0JZ30+Frn4xz3zuFHSFCE2Sf/wOwde00DlAPgQ0OF1o84zx8jBLYuC QjtuBY8Uh9UTXcC3rB3ZWmtr4qhYk0p519g19Oyah7110/yIyUpb+aZYwfaNUDWXGBRvFKHup/Sg6 w31QqIbgVm1C71s0QtZONoliwaatfWJ9oy1LT/OmggSIJS1KxwNqmnGq8HNOToq1UtGkpXu/REWzB MXJkzRcToXoSQmRMBdOY4zmmdWG6XwLr7hKcv2NWP1wDkmLD0vEk7WuMbYsgqz/XgSeVCm6pWchcI W08aR/EQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4T1E-0006Lh-1T; Wed, 19 Feb 2020 17:20:16 +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 D4845300606; Wed, 19 Feb 2020 18:18:21 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 17DA920AFA9B7; Wed, 19 Feb 2020 18:20:14 +0100 (CET) Date: Wed, 19 Feb 2020 18:20:14 +0100 From: Peter Zijlstra To: Dmitry Vyukov Cc: LKML , linux-arch , Steven Rostedt , Ingo Molnar , Joel Fernandes , Greg Kroah-Hartman , "Gustavo A. R. Silva" , Thomas Gleixner , "Paul E. McKenney" , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Andy Lutomirski , tony.luck@intel.com, Frederic Weisbecker , Dan Carpenter , Masami Hiramatsu , Andrey Ryabinin , kasan-dev Subject: Re: [PATCH v3 22/22] x86/int3: Ensure that poke_int3_handler() is not sanitized Message-ID: <20200219172014.GI14946@hirez.programming.kicks-ass.net> References: <20200219144724.800607165@infradead.org> <20200219150745.651901321@infradead.org> <20200219163025.GH18400@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200219163025.GH18400@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 19, 2020 at 05:30:25PM +0100, Peter Zijlstra wrote: > By inlining everything in poke_int3_handler() (except bsearch :/) we can > mark the whole function off limits to everything and call it a day. That > simplicity has been the guiding principle so far. > > Alternatively we can provide an __always_inline variant of bsearch(). This reduces the __no_sanitize usage to just the exception entry (do_int3) and the critical function: poke_int3_handler(). Is this more acceptible? --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -979,7 +979,7 @@ static __always_inline void *text_poke_a return _stext + tp->rel_addr; } -static int notrace __no_sanitize patch_cmp(const void *key, const void *elt) +static __always_inline int patch_cmp(const void *key, const void *elt) { struct text_poke_loc *tp = (struct text_poke_loc *) elt; @@ -989,7 +989,6 @@ static int notrace __no_sanitize patch_c return 1; return 0; } -NOKPROBE_SYMBOL(patch_cmp); int notrace __no_sanitize poke_int3_handler(struct pt_regs *regs) { @@ -1024,9 +1023,9 @@ int notrace __no_sanitize poke_int3_hand * Skip the binary search if there is a single member in the vector. */ if (unlikely(desc->nr_entries > 1)) { - tp = bsearch(ip, desc->vec, desc->nr_entries, - sizeof(struct text_poke_loc), - patch_cmp); + tp = __bsearch(ip, desc->vec, desc->nr_entries, + sizeof(struct text_poke_loc), + patch_cmp); if (!tp) goto out_put; } else { --- a/include/linux/bsearch.h +++ b/include/linux/bsearch.h @@ -4,7 +4,29 @@ #include -void *bsearch(const void *key, const void *base, size_t num, size_t size, - cmp_func_t cmp); +static __always_inline +void *__bsearch(const void *key, const void *base, size_t num, size_t size, cmp_func_t cmp) +{ + const char *pivot; + int result; + + while (num > 0) { + pivot = base + (num >> 1) * size; + result = cmp(key, pivot); + + if (result == 0) + return (void *)pivot; + + if (result > 0) { + base = pivot + size; + num--; + } + num >>= 1; + } + + return NULL; +} + +extern void *bsearch(const void *key, const void *base, size_t num, size_t size, cmp_func_t cmp); #endif /* _LINUX_BSEARCH_H */ --- a/lib/bsearch.c +++ b/lib/bsearch.c @@ -28,27 +28,9 @@ * the key and elements in the array are of the same type, you can use * the same comparison function for both sort() and bsearch(). */ -void __no_sanitize *bsearch(const void *key, const void *base, size_t num, size_t size, - cmp_func_t cmp) +void *bsearch(const void *key, const void *base, size_t num, size_t size, cmp_func_t cmp) { - const char *pivot; - int result; - - while (num > 0) { - pivot = base + (num >> 1) * size; - result = cmp(key, pivot); - - if (result == 0) - return (void *)pivot; - - if (result > 0) { - base = pivot + size; - num--; - } - num >>= 1; - } - - return NULL; + __bsearch(key, base, num, size, cmp); } EXPORT_SYMBOL(bsearch); NOKPROBE_SYMBOL(bsearch);