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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 8FD61C3A5A1 for ; Thu, 22 Aug 2019 17:29:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6799C23402 for ; Thu, 22 Aug 2019 17:29:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566494978; bh=sRrp4AB5ZZgmgXo65N7/Viju2DCUUVDpt6ASET+gznA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=i8JG3qflSn5FEDF4zF1F2YspgXUxAxR7Sb0t502+9ChkxLOi7YRQLq0hks1n3KBUx WuKfjn+0DlZP2YXYD46bNxwycLPXeR3dpy0/mWhVrJ7KTYSXCc7Vbds2k+7e0ibN6t Rspmhmejn7wK7R8bPoOuGi6vhIa48f6oXMyqkbK0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404827AbfHVR1i (ORCPT ); Thu, 22 Aug 2019 13:27:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:51134 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404603AbfHVR0G (ORCPT ); Thu, 22 Aug 2019 13:26:06 -0400 Received: from localhost (wsip-184-188-36-2.sd.sd.cox.net [184.188.36.2]) (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 AD1F9206DD; Thu, 22 Aug 2019 17:26:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566494765; bh=sRrp4AB5ZZgmgXo65N7/Viju2DCUUVDpt6ASET+gznA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z17/3clyvxm5nlhXTRmEnMrpX0mXIrdvI8oZaumun4bsfiDmpSlSdEp7EQiqWC0xf W3+Ha0/qOP6XyV+evJc0fH+x8ZjtuPlJrZVsloUAD6+0Qum1H+p5/s/JBjZbLLWyWm zfZe9wnujRxCXEJVe75+PWsAjoJHRH0qtTecDU9c= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ard Biesheuvel , James Morse , Will Deacon , Catalin Marinas Subject: [PATCH 4.19 69/85] arm64: ftrace: Ensure module ftrace trampoline is coherent with I-side Date: Thu, 22 Aug 2019 10:19:42 -0700 Message-Id: <20190822171734.175450632@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190822171731.012687054@linuxfoundation.org> References: <20190822171731.012687054@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: Will Deacon commit b6143d10d23ebb4a77af311e8b8b7f019d0163e6 upstream. The initial support for dynamic ftrace trampolines in modules made use of an indirect branch which loaded its target from the beginning of a special section (e71a4e1bebaf7 ("arm64: ftrace: add support for far branches to dynamic ftrace")). Since no instructions were being patched, no cache maintenance was needed. However, later in be0f272bfc83 ("arm64: ftrace: emit ftrace-mod.o contents through code") this code was reworked to output the trampoline instructions directly into the PLT entry but, unfortunately, the necessary cache maintenance was overlooked. Add a call to __flush_icache_range() after writing the new trampoline instructions but before patching in the branch to the trampoline. Cc: Ard Biesheuvel Cc: James Morse Cc: Fixes: be0f272bfc83 ("arm64: ftrace: emit ftrace-mod.o contents through code") Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/ftrace.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -76,7 +76,7 @@ int ftrace_make_call(struct dyn_ftrace * if (offset < -SZ_128M || offset >= SZ_128M) { #ifdef CONFIG_ARM64_MODULE_PLTS - struct plt_entry trampoline; + struct plt_entry trampoline, *dst; struct module *mod; /* @@ -104,24 +104,27 @@ int ftrace_make_call(struct dyn_ftrace * * is added in the future, but for now, the pr_err() below * deals with a theoretical issue only. */ + dst = mod->arch.ftrace_trampoline; trampoline = get_plt_entry(addr); - if (!plt_entries_equal(mod->arch.ftrace_trampoline, - &trampoline)) { - if (!plt_entries_equal(mod->arch.ftrace_trampoline, - &(struct plt_entry){})) { + if (!plt_entries_equal(dst, &trampoline)) { + if (!plt_entries_equal(dst, &(struct plt_entry){})) { pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n"); return -EINVAL; } /* point the trampoline to our ftrace entry point */ module_disable_ro(mod); - *mod->arch.ftrace_trampoline = trampoline; + *dst = trampoline; module_enable_ro(mod, true); - /* update trampoline before patching in the branch */ - smp_wmb(); + /* + * Ensure updated trampoline is visible to instruction + * fetch before we patch in the branch. + */ + __flush_icache_range((unsigned long)&dst[0], + (unsigned long)&dst[1]); } - addr = (unsigned long)(void *)mod->arch.ftrace_trampoline; + addr = (unsigned long)dst; #else /* CONFIG_ARM64_MODULE_PLTS */ return -EINVAL; #endif /* CONFIG_ARM64_MODULE_PLTS */