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 D311EC433EF for ; Thu, 26 May 2022 11:05:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237382AbiEZLE5 (ORCPT ); Thu, 26 May 2022 07:04:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347117AbiEZLD1 (ORCPT ); Thu, 26 May 2022 07:03:27 -0400 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 5A600CEBB1 for ; Thu, 26 May 2022 04:03:25 -0700 (PDT) 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=r2eMVpFl0Aac8ZRjWQ0+nV5mtEZevDgIYgdhVMNcaMU=; b=ddtwCTdp7TmAveVJV4GZ6oZ2EW DZ6hSBOhETw366mfCbUmUSceZ3TcxCj1fpTmOpY8gfM1z1Y7S+noMvxjDxra8ZlPQNAXnO8XephSN W12Ytvs7Ypz5/b4VPlcQYIGOqsw1qL7PQHp6e4RNKcNBWBV9XXwSNKb8faWL6D7JMj58j6LdmIW5Z 5l8lnknUq6946GsSfPeM6bj1znYJahzyHUR6jbFsSW4R7p6nYCNaOU3tG35Aoz6LISKPOeIEF+8fv l1RbiDQB8ecgVD4ZxgeU77SoIz3EA9AGWSngaLToKvIwOZLdPBi4gw8eFEqZk0b1HGisItOD2n9ti NMljld9g==; 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 1nuBGX-001sVg-Jc; Thu, 26 May 2022 11:02:56 +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) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 932E030003C; Thu, 26 May 2022 13:02:50 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 6DCBF2025FE5B; Thu, 26 May 2022 13:02:50 +0200 (CEST) Message-ID: <20220526105957.817269865@infradead.org> User-Agent: quilt/0.66 Date: Thu, 26 May 2022 12:52:54 +0200 From: Peter Zijlstra To: x86@kernel.org, jpoimboe@redhat.com Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, elver@google.com, jbaron@akamai.com, rostedt@goodmis.org, ardb@kernel.org, mark.rutland@arm.com Subject: [PATCH 2/7] objtool: Extend UNWIND_HINT based ENDBR rules References: <20220526105252.440440893@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 Extend the UNWIND hint driven rules for ENDBR placement. Currently objtool expects an ENDBR at any UNWINT_HINT_IRET_REGS that is at +0 of an STB_GLOBAL symbol, with the expectation that this is an exception entry point. Extend this to also expect ENDBR at UNWIND_HINT_EMPTY at +0 for STB_GLOBAL symbols, with the expectation that these are also machine entry points (SYSCALL et. al.). This guarantees all machine entry points are covered by objtool rules at the expense of a few additional false positives: vmlinux.o: warning: objtool: startup_64+0x0: UNWIND_HINT_EMPTY without ENDBR vmlinux.o: warning: objtool: start_cpu0+0x0: UNWIND_HINT_EMPTY without ENDBR Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/head_64.S | 2 ++ tools/objtool/check.c | 23 ++++++++++++++++++----- 2 files changed, 20 insertions(+), 5 deletions(-) --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -43,6 +43,7 @@ L3_START_KERNEL = pud_index(__START_KERN .code64 SYM_CODE_START_NOALIGN(startup_64) UNWIND_HINT_EMPTY + ANNOTATE_NOENDBR /* * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0, * and someone has loaded an identity mapped page table @@ -371,6 +372,7 @@ SYM_CODE_END(secondary_startup_64) */ SYM_CODE_START(start_cpu0) UNWIND_HINT_EMPTY + ANNOTATE_NOENDBR movq initial_stack(%rip), %rsp jmp .Ljump_to_C_code SYM_CODE_END(start_cpu0) --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1947,14 +1947,27 @@ static int read_unwind_hints(struct objt insn->hint = true; - if (opts.ibt && hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) { + if (opts.ibt) { struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset); - if (sym && sym->bind == STB_GLOBAL && - insn->type != INSN_ENDBR && !insn->noendbr) { - WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR", - insn->sec, insn->offset); + if (!sym || sym->bind != STB_GLOBAL) + goto no_entry; + + if (hint->type == UNWIND_HINT_TYPE_CALL && !hint->sp_reg) { + if (insn->type != INSN_ENDBR && !insn->noendbr) { + WARN_FUNC("UNWIND_HINT_EMPTY without ENDBR", + insn->sec, insn->offset); + } + } + + if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) { + if (insn->type != INSN_ENDBR && !insn->noendbr) { + WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR", + insn->sec, insn->offset); + } } + +no_entry: ; } if (hint->type == UNWIND_HINT_TYPE_FUNC) {