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 6AC9AC54EBE for ; Mon, 16 Jan 2023 16:22:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231453AbjAPQWN (ORCPT ); Mon, 16 Jan 2023 11:22:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232930AbjAPQVl (ORCPT ); Mon, 16 Jan 2023 11:21:41 -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 8A89030B02 for ; Mon, 16 Jan 2023 08:12:03 -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 1D0D661040 for ; Mon, 16 Jan 2023 16:12:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 30103C433EF; Mon, 16 Jan 2023 16:12:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673885522; bh=8I1jP4PadQmrWdYEFiyq1IJc21Pb/b6fRDBV2NKZdEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DCwk2j6foy1qmTusogvG7dGwZsYNdo7CJA1ZTNKqnm3+3zyOZufGMRGvO1CiDYwA8 zkOtUEt7xB0Sz71D3X4alOdHgsYu8D2B9sgP/qogz1kOyjFwyFGKkdhoSngbefRViN Vjzi07HChW3kOvk9TEi2udaw21spSjaZjkflzg4s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Seiji Nishikawa , Denys Vlasenko , Oleg Nesterov , Thomas Gleixner , "Masami Hiramatsu (Google)" , Sasha Levin Subject: [PATCH 5.4 083/658] uprobes/x86: Allow to probe a NOP instruction with 0x66 prefix Date: Mon, 16 Jan 2023 16:42:51 +0100 Message-Id: <20230116154913.388680409@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116154909.645460653@linuxfoundation.org> References: <20230116154909.645460653@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: Oleg Nesterov [ Upstream commit cefa72129e45313655d53a065b8055aaeb01a0c9 ] Intel ICC -hotpatch inserts 2-byte "0x66 0x90" NOP at the start of each function to reserve extra space for hot-patching, and currently it is not possible to probe these functions because branch_setup_xol_ops() wrongly rejects NOP with REP prefix as it treats them like word-sized branch instructions. Fixes: 250bbd12c2fe ("uprobes/x86: Refuse to attach uprobe to "word-sized" branch insns") Reported-by: Seiji Nishikawa Suggested-by: Denys Vlasenko Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Acked-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20221204173933.GA31544@redhat.com Signed-off-by: Sasha Levin --- arch/x86/kernel/uprobes.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index fae5b00cbccf..f51fc7fde3a0 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -722,8 +722,9 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) switch (opc1) { case 0xeb: /* jmp 8 */ case 0xe9: /* jmp 32 */ - case 0x90: /* prefix* + nop; same as jmp with .offs = 0 */ break; + case 0x90: /* prefix* + nop; same as jmp with .offs = 0 */ + goto setup; case 0xe8: /* call relative */ branch_clear_offset(auprobe, insn); @@ -753,6 +754,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) return -ENOTSUPP; } +setup: auprobe->branch.opc1 = opc1; auprobe->branch.ilen = insn->length; auprobe->branch.offs = insn->immediate.value; -- 2.35.1