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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 D99DEC433F1 for ; Mon, 20 Jul 2020 15:57:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF7C422CAF for ; Mon, 20 Jul 2020 15:57:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260658; bh=egxt+OqgdvW57MofFR/h1DolS9Q1TbBM33DDluq4gHE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2pgbKCl2ggeVD5XArYHUy1Ckn46zNHqEnjyrNHY0RJeWuLIKsJCuXKxOPNExUeakA uVoyVxbq7GjPKQUXLkeoP59R5zGr2SM52d6m4dk2j6bJ0ZDLVjR/bilacvM+M4TAOR 05ZsuUIHXD9VnWBQclEObBOBYkxw1cSk1mVkTV28= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731937AbgGTP5h (ORCPT ); Mon, 20 Jul 2020 11:57:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:57422 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731627AbgGTP5a (ORCPT ); Mon, 20 Jul 2020 11:57:30 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 14BB72065E; Mon, 20 Jul 2020 15:57:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260649; bh=egxt+OqgdvW57MofFR/h1DolS9Q1TbBM33DDluq4gHE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yugVC8FI/y9+Jvc+wMxY01RADixhc+Z5RfBkLZluvwy9QG+QoR3hPV0EW1ERCy3+F K+RSuV/eCO5nBKCtDyUr2n17dZLKN+aj4wXRHhBnl1pMwm3P+ry0W9i8bDgMxHbKC+ VsguS6vaqtelVw4lZx81kknopWR9sahkwkR2iNGQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexandru Elisei , Ard Biesheuvel , Will Deacon , Sasha Levin Subject: [PATCH 5.4 045/215] arm64/alternatives: dont patch up internal branches Date: Mon, 20 Jul 2020 17:35:27 +0200 Message-Id: <20200720152822.340606082@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152820.122442056@linuxfoundation.org> References: <20200720152820.122442056@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ard Biesheuvel [ Upstream commit 5679b28142193a62f6af93249c0477be9f0c669b ] Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences") moved the alternatives replacement sequences into subsections, in order to keep the as close as possible to the code that they replace. Unfortunately, this broke the logic in branch_insn_requires_update, which assumed that any branch into kernel executable code was a branch that required updating, which is no longer the case now that the code sequences that are patched in are in the same section as the patch site itself. So the only way to discriminate branches that require updating and ones that don't is to check whether the branch targets the replacement sequence itself, and so we can drop the call to kernel_text_address() entirely. Fixes: f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences") Reported-by: Alexandru Elisei Signed-off-by: Ard Biesheuvel Tested-by: Alexandru Elisei Link: https://lore.kernel.org/r/20200709125953.30918-1-ardb@kernel.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/alternative.c | 16 ++-------------- 1 file changed, 2 insertions(+), 14 deletions(-) diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c index d1757ef1b1e74..73039949b5ce2 100644 --- a/arch/arm64/kernel/alternative.c +++ b/arch/arm64/kernel/alternative.c @@ -43,20 +43,8 @@ bool alternative_is_applied(u16 cpufeature) */ static bool branch_insn_requires_update(struct alt_instr *alt, unsigned long pc) { - unsigned long replptr; - - if (kernel_text_address(pc)) - return true; - - replptr = (unsigned long)ALT_REPL_PTR(alt); - if (pc >= replptr && pc <= (replptr + alt->alt_len)) - return false; - - /* - * Branching into *another* alternate sequence is doomed, and - * we're not even trying to fix it up. - */ - BUG(); + unsigned long replptr = (unsigned long)ALT_REPL_PTR(alt); + return !(pc >= replptr && pc <= (replptr + alt->alt_len)); } #define align_down(x, a) ((unsigned long)(x) & ~(((unsigned long)(a)) - 1)) -- 2.25.1