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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B4F7C433FE for ; Thu, 24 Feb 2022 15:19:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235975AbiBXPUK (ORCPT ); Thu, 24 Feb 2022 10:20:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235987AbiBXPSc (ORCPT ); Thu, 24 Feb 2022 10:18:32 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 462E9159280 for ; Thu, 24 Feb 2022 07:17:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=gyQOZ/OewxIV9rsoR2cpSRnntRDVjwTBBtcxSpgojPk=; b=G8mxPQm3NU7ZV/zLjmPmTh333F ltP75Fc9ZTdxk0Ikc5JZd86lcWO8ZFrnZFSiHXyUwBH7v95v794zZiqTjtHlYMRXYobsTu0JClaao HMjQV4MWpw8i7eRG464mRlWHYxRIxfspn/F2CQI46Evm47hJw69zjug3h2IT9fXkmGRCikzCDqpg2 N/OdKOQq63tzHJ6Xsr7VYxD+5ecckOPM5EJtRa5mm+wiFJEtAlOyDCVgCCZVeaxjuJ7bHLgUJR86d T2YpACOUwA+7V9EnNjxJUsDrIKq1tzDRZWxpd58btziLmHhoqkEEmI2QGEmKEso0Ke5AAwXyZamGD iaM/rNKg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nNFs3-00CeLh-Nl; Thu, 24 Feb 2022 15:17:31 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 38BAA301A96; Thu, 24 Feb 2022 16:17:29 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 59AA02B354785; Thu, 24 Feb 2022 16:17:28 +0100 (CET) Message-ID: <20220224151322.892372059@infradead.org> User-Agent: quilt/0.66 Date: Thu, 24 Feb 2022 15:51:53 +0100 From: Peter Zijlstra To: x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com, jpoimboe@redhat.com, andrew.cooper3@citrix.com Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, ndesaulniers@google.com, keescook@chromium.org, samitolvanen@google.com, mark.rutland@arm.com, alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org, mhiramat@kernel.org, alexei.starovoitov@gmail.com Subject: [PATCH v2 15/39] x86/ibt,kprobes: Fix more +0 assumptions References: <20220224145138.952963315@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With IBT on, sym+0 is no longer the __fentry__ site. NOTE: the architecture has a special case and *does* allow placing an INT3 breakpoint over ENDBR in which case #BP has precedence over #CP and as such we don't need to disallow probing these instructions. NOTE: irrespective of the above; there is a complication in that direct branches to functions are rewritten to not execute ENDBR, so any breakpoint thereon might miss lots of actual function executions. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/kprobes/core.c | 11 +++++++++++ kernel/kprobes.c | 15 ++++++++++++--- 2 files changed, 23 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -1156,3 +1162,8 @@ int arch_trampoline_kprobe(struct kprobe { return 0; } + +bool arch_kprobe_on_func_entry(unsigned long offset) +{ + return offset <= 4*HAS_KERNEL_IBT; +} --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -67,10 +67,19 @@ static bool kprobes_all_disarmed; static DEFINE_MUTEX(kprobe_mutex); static DEFINE_PER_CPU(struct kprobe *, kprobe_instance); -kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, - unsigned int __unused) +kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, unsigned int offset) { - return ((kprobe_opcode_t *)(kallsyms_lookup_name(name))); + kprobe_opcode_t *addr = NULL; + + addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name))); +#ifdef CONFIG_KPROBES_ON_FTRACE + if (addr && !offset) { + unsigned long faddr = ftrace_location((unsigned long)addr); + if (faddr) + addr = (kprobe_opcode_t *)faddr; + } +#endif + return addr; } /*