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 C762EC4332F for ; Wed, 4 Jan 2023 16:19:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239942AbjADQTD (ORCPT ); Wed, 4 Jan 2023 11:19:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239977AbjADQS5 (ORCPT ); Wed, 4 Jan 2023 11:18:57 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36EE118B3A for ; Wed, 4 Jan 2023 08:18:53 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C9D146177F for ; Wed, 4 Jan 2023 16:18:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BBCB0C433D2; Wed, 4 Jan 2023 16:18:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672849132; bh=8+vgRJSH5a1+wjv0k+f0IWtfwJNNdxCpLzpTrTPIL8E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QcwzjZe9MhAW4cIFdt/LaBLUtrhB+mcjihPVhq8Ltkiq+3i0Y4q+ZAUsllvzb376s g9JjLBBN7b5p5xwS65AwnSD6Gvcl0KEbWumQQKPqqw39B2lVgMEacCbPnodJ6rrOwH t6oRWJ1z6K3K9rGx80/cLrgt1pAtvgXxVN7FeuPo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peter Zijlstra , "Masami Hiramatsu (Google)" Subject: [PATCH 6.0 066/177] x86/kprobes: Fix optprobe optimization check with CONFIG_RETHUNK Date: Wed, 4 Jan 2023 17:05:57 +0100 Message-Id: <20230104160509.656510905@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230104160507.635888536@linuxfoundation.org> References: <20230104160507.635888536@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Masami Hiramatsu (Google) commit 63dc6325ff41ee9e570bde705ac34a39c5dbeb44 upstream. Since the CONFIG_RETHUNK and CONFIG_SLS will use INT3 for stopping speculative execution after function return, kprobe jump optimization always fails on the functions with such INT3 inside the function body. (It already checks the INT3 padding between functions, but not inside the function) To avoid this issue, as same as kprobes, check whether the INT3 comes from kgdb or not, and if so, stop decoding and make it fail. The other INT3 will come from CONFIG_RETHUNK/CONFIG_SLS and those can be treated as a one-byte instruction. Fixes: e463a09af2f0 ("x86: Add straight-line-speculation mitigation") Suggested-by: Peter Zijlstra Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/167146051929.1374301.7419382929328081706.stgit@devnote3 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/kprobes/opt.c | 28 ++++++++-------------------- 1 file changed, 8 insertions(+), 20 deletions(-) --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -279,19 +280,6 @@ static int insn_is_indirect_jump(struct return ret; } -static bool is_padding_int3(unsigned long addr, unsigned long eaddr) -{ - unsigned char ops; - - for (; addr < eaddr; addr++) { - if (get_kernel_nofault(ops, (void *)addr) < 0 || - ops != INT3_INSN_OPCODE) - return false; - } - - return true; -} - /* Decode whole function to ensure any instructions don't jump into target */ static int can_optimize(unsigned long paddr) { @@ -334,15 +322,15 @@ static int can_optimize(unsigned long pa ret = insn_decode_kernel(&insn, (void *)recovered_insn); if (ret < 0) return 0; - +#ifdef CONFIG_KGDB /* - * In the case of detecting unknown breakpoint, this could be - * a padding INT3 between functions. Let's check that all the - * rest of the bytes are also INT3. + * If there is a dynamically installed kgdb sw breakpoint, + * this function should not be probed. */ - if (insn.opcode.bytes[0] == INT3_INSN_OPCODE) - return is_padding_int3(addr, paddr - offset + size) ? 1 : 0; - + if (insn.opcode.bytes[0] == INT3_INSN_OPCODE && + kgdb_has_hit_break(addr)) + return 0; +#endif /* Recover address */ insn.kaddr = (void *)addr; insn.next_byte = (void *)(addr + insn.length);