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=-15.8 required=3.0 tests=BAYES_00,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 autolearn=ham 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 47E76C433DB for ; Fri, 19 Feb 2021 21:11:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9EC76148E for ; Fri, 19 Feb 2021 21:11:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229734AbhBSVLA (ORCPT ); Fri, 19 Feb 2021 16:11:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229623AbhBSVK4 (ORCPT ); Fri, 19 Feb 2021 16:10:56 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C964C061786 for ; Fri, 19 Feb 2021 13:10:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; 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=BFzdNc4Al+4SwJijnkTefSWEjv9BX66AFUmawVT+FnY=; b=eoHDOS6o6dmNloHFdV7o9nMtgi afZow+ME621FXQHQd6qSyjU4Ph6pgKZMrkZW5ZmRltzBoTPu2ybVpARQs4FfMW8B01TCSAmuyhKaa 4Wazjr3TWWS6Qgs+TkTyQrM4VnOMhNXzA162CRlNDezs2WffSsXKwq0AYiIRzEjonXw9d9S+psZCh zysloMGQ6Y4DXHmJ7Wx3ZtuLNMJkeO0IrCWKN7lE9aWc5fjq49WeppfXvMmtQS5FcYP3rq7f00F6j aTYGBOa1QEfQFoEWJ0s0sYo1ka9bBs9rCX5de+xgiVZeP3IWzNq+ndyoa+5mEpZU2oaksyrCztvK5 O1Ha+i0A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1lDD2N-0006Ga-U3; Fri, 19 Feb 2021 21:10:08 +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 9E7DC3070D5; Fri, 19 Feb 2021 22:10:05 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 526972021555F; Fri, 19 Feb 2021 22:10:05 +0100 (CET) Message-ID: <20210219210535.431965352@infradead.org> User-Agent: quilt/0.66 Date: Fri, 19 Feb 2021 21:43:05 +0100 From: Peter Zijlstra To: jpoimboe@redhat.com, x86@kernel.org, pjt@google.com, mbenes@suze.cz, jgross@suse.com Cc: linux-kernel@vger.kernel.org, peterz@infradead.org Subject: [RFC][PATCH 5/6] objtool: Allow archs to rewrite retpolines References: <20210219204300.749932493@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 When retpolines are employed, compilers typically emit calls to retpoline thunks. Objtool recognises these calls and marks them as dynamic calls. Provide infrastructure for architectures to rewrite/augment what the compiler wrote for us. Signed-off-by: Peter Zijlstra (Intel) --- tools/objtool/check.c | 23 +++++++++++++++++++++-- tools/objtool/include/objtool/arch.h | 3 +++ 2 files changed, 24 insertions(+), 2 deletions(-) --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -775,6 +775,14 @@ static int add_ignore_alternatives(struc return 0; } + +__weak int arch_rewrite_retpoline(struct objtool_file *file, + struct instruction *insn, + struct reloc *reloc) +{ + return 0; +} + /* * Find the destination instructions for all jumps. */ @@ -808,6 +816,9 @@ static int add_jump_destinations(struct insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL; insn->retpoline_safe = true; + + arch_rewrite_retpoline(file, insn, reloc); + continue; } else if (insn->func) { /* internal or external sibling call (with reloc) */ @@ -959,6 +970,8 @@ static int add_call_destinations(struct insn->type = INSN_CALL_DYNAMIC; insn->retpoline_safe = true; + arch_rewrite_retpoline(file, insn, reloc); + remove_insn_ops(insn); continue; @@ -1119,6 +1132,8 @@ static int handle_group_alt(struct objto dest_off = arch_jump_destination(insn); if (dest_off == special_alt->new_off + special_alt->new_len) insn->jump_dest = next_insn_same_sec(file, last_orig_insn); + else + insn->jump_dest = find_insn(file, insn->sec, dest_off); if (!insn->jump_dest) { WARN_FUNC("can't find alternative jump destination", @@ -1704,11 +1719,15 @@ static int decode_sections(struct objtoo if (ret) return ret; - ret = add_jump_destinations(file); + /* + * Must be before add_{jump,call}_destination; for they can add + * magic alternatives we can't actually parse. + */ + ret = add_special_section_alts(file); if (ret) return ret; - ret = add_special_section_alts(file); + ret = add_jump_destinations(file); if (ret) return ret; --- a/tools/objtool/include/objtool/arch.h +++ b/tools/objtool/include/objtool/arch.h @@ -82,6 +82,9 @@ unsigned long arch_jump_destination(stru unsigned long arch_dest_reloc_offset(int addend); const char *arch_nop_insn(int len); +int arch_rewrite_retpoline(struct objtool_file *file, + struct instruction *insn, + struct reloc *reloc); int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg);