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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 C61ECC43381 for ; Fri, 29 Mar 2019 04:35:13 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 07508206BA for ; Fri, 29 Mar 2019 04:35:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 07508206BA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=informatik.wtf Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44Vpn968FDzDqQd for ; Fri, 29 Mar 2019 15:35:09 +1100 (AEDT) Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44VplJ0KqRzDqPM for ; Fri, 29 Mar 2019 15:33:32 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=informatik.wtf Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) by bilbo.ozlabs.org (Postfix) with ESMTP id 44VplH4p95z8tDh for ; Fri, 29 Mar 2019 15:33:31 +1100 (AEDT) Received: by ozlabs.org (Postfix) id 44VplH4P4zz9sQm; Fri, 29 Mar 2019 15:33:31 +1100 (AEDT) Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=informatik.wtf (client-ip=198.54.127.52; helo=new-02-3.privateemail.com; envelope-from=cmr@informatik.wtf; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=informatik.wtf X-Greylist: delayed 834 seconds by postgrey-1.36 at bilbo; Fri, 29 Mar 2019 15:33:30 AEDT Received: from NEW-02-3.privateemail.com (new-02-3.privateemail.com [198.54.127.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 44VplG4X6vz9sPL; Fri, 29 Mar 2019 15:33:29 +1100 (AEDT) Received: from MTA-07-1.privateemail.com (unknown [10.20.147.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by NEW-02.privateemail.com (Postfix) with ESMTPS id 6EFFA604F5; Fri, 29 Mar 2019 04:19:31 +0000 (UTC) Received: from MTA-07.privateemail.com (localhost [127.0.0.1]) by MTA-07.privateemail.com (Postfix) with ESMTP id 4D5F160049; Fri, 29 Mar 2019 00:19:31 -0400 (EDT) Received: from wrwlf0000.attlocal.net (unknown [10.20.151.216]) by MTA-07.privateemail.com (Postfix) with ESMTPA id DE9D26004B; Fri, 29 Mar 2019 04:19:30 +0000 (UTC) From: cmr To: linuxppc-dev@ozlabs.org Subject: [PATCH] powerpc/xmon: add read-only mode Date: Thu, 28 Mar 2019 23:21:53 -0500 Message-Id: <20190329042153.25698-1-cmr@informatik.wtf> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Virus-Scanned: ClamAV using ClamSMTP X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: cmr , andonnel@au1.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Operations which write to memory should be restricted on secure systems and optionally to avoid self-destructive behaviors. Add a config option, XMON_RO, to control default xmon behavior along with kernel cmdline options xmon=ro and xmon=rw for explicit control. The default is to enable read-only mode. The following xmon operations are affected: memops: disable memmove disable memset memex: no-op'd mwrite super_regs: no-op'd write_spr bpt_cmds: disable proc_call: disable Signed-off-by: cmr --- arch/powerpc/Kconfig.debug | 7 +++++++ arch/powerpc/xmon/xmon.c | 24 ++++++++++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug index 4e00cb0a5464..33cc01adf4cb 100644 --- a/arch/powerpc/Kconfig.debug +++ b/arch/powerpc/Kconfig.debug @@ -117,6 +117,13 @@ config XMON_DISASSEMBLY to say Y here, unless you're building for a memory-constrained system. +config XMON_RO + bool "Set xmon read-only mode" + depends on XMON + default y + help + Disable state- and memory-altering write operations in xmon. + config DEBUGGER bool depends on KGDB || XMON diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index a0f44f992360..c13ee73cdfd4 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -80,6 +80,7 @@ static int set_indicator_token = RTAS_UNKNOWN_SERVICE; #endif static unsigned long in_xmon __read_mostly = 0; static int xmon_on = IS_ENABLED(CONFIG_XMON_DEFAULT); +static int xmon_ro = IS_ENABLED(CONFIG_XMON_RO); static unsigned long adrs; static int size = 1; @@ -1042,6 +1043,8 @@ cmds(struct pt_regs *excp) set_lpp_cmd(); break; case 'b': + if (xmon_ro == 1) + break; bpt_cmds(); break; case 'C': @@ -1055,6 +1058,8 @@ cmds(struct pt_regs *excp) bootcmds(); break; case 'p': + if (xmon_ro == 1) + break; proccall(); break; case 'P': @@ -1777,6 +1782,9 @@ read_spr(int n, unsigned long *vp) static void write_spr(int n, unsigned long val) { + if (xmon_ro == 1) + return; + if (setjmp(bus_error_jmp) == 0) { catch_spr_faults = 1; sync(); @@ -2016,6 +2024,10 @@ mwrite(unsigned long adrs, void *buf, int size) char *p, *q; n = 0; + + if (xmon_ro == 1) + return n; + if (setjmp(bus_error_jmp) == 0) { catch_memory_errors = 1; sync(); @@ -2884,9 +2896,13 @@ memops(int cmd) scanhex((void *)&mcount); switch( cmd ){ case 'm': + if (xmon_ro == 1) + break; memmove((void *)mdest, (void *)msrc, mcount); break; case 's': + if (xmon_ro == 1) + break; memset((void *)mdest, mval, mcount); break; case 'd': @@ -3796,6 +3812,14 @@ static int __init early_parse_xmon(char *p) } else if (strncmp(p, "on", 2) == 0) { xmon_init(1); xmon_on = 1; + } else if (strncmp(p, "rw", 2) == 0) { + xmon_init(1); + xmon_on = 1; + xmon_ro = 0; + } else if (strncmp(p, "ro", 2) == 0) { + xmon_init(1); + xmon_on = 1; + xmon_ro = 1; } else if (strncmp(p, "off", 3) == 0) xmon_on = 0; else -- 2.21.0