From patchwork Thu Sep 13 15:03:26 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Vorontsov X-Patchwork-Id: 1453031 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (unknown [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id 9605BDF24C for ; Thu, 13 Sep 2012 15:18:43 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TCB0A-0002Qk-QF; Thu, 13 Sep 2012 15:06:46 +0000 Received: from mail-pz0-f49.google.com ([209.85.210.49]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TCAzt-0002LS-Ss for linux-arm-kernel@lists.infradead.org; Thu, 13 Sep 2012 15:06:31 +0000 Received: by dajq27 with SMTP id q27so417124daj.36 for ; Thu, 13 Sep 2012 08:06:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references :x-gm-message-state; bh=Y2j2AzG2cP8jdh2bOQPhPQZVCIJ25PJnsSsj5ZZUrJ4=; b=IxuXSYeh0akVoDCBryzY/6ZlU+aSsv8ougy6aOsOi5UTNbkgJnuE6IrNexK9ND8l5w CAWqXNWndg1G8B2dwKB1nglhaXwSZkpIk4wFG42wInhHW7abAhsASKMO3V+wKoPZ4Y+z /D601ugRgnjMYoMYVIXMiFwvKY6gBOpC0uGqH/rbpkx0GrKputSZVF7t7nkJbMRmBmOJ 5GyFhOZcCOaAnb0a7QvEnNuCtTPLkmLDDmgJCJiAPPgaLOBqx8RF+x3RFG8+N01E2Tgo J9uPM/HxDE/xNLjeMwoUeu3J8dDwlViGuKxphsNv9rGXc7vEPoD3bR3CQztA9Ld6+ou7 2Xzg== Received: by 10.68.116.232 with SMTP id jz8mr5124619pbb.77.1347548789037; Thu, 13 Sep 2012 08:06:29 -0700 (PDT) Received: from localhost (c-71-204-165-222.hsd1.ca.comcast.net. [71.204.165.222]) by mx.google.com with ESMTPS id jz10sm13219172pbc.8.2012.09.13.08.06.27 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 13 Sep 2012 08:06:28 -0700 (PDT) From: Anton Vorontsov To: Andrew Morton , Russell King , Jason Wessel , Greg Kroah-Hartman , Alan Cox Subject: [PATCH 02/11] kdb: Implement disable_nmi command Date: Thu, 13 Sep 2012 08:03:26 -0700 Message-Id: <1347548615-18227-2-git-send-email-anton.vorontsov@linaro.org> X-Mailer: git-send-email 1.7.11.5 In-Reply-To: <20120913150133.GA16238@lizard> References: <20120913150133.GA16238@lizard> X-Gm-Message-State: ALoCoQkutFTSy8/LPkoPmTJ50sSIkKJdpyB/I4zE1+rJMRMahC6MFKKpvsVqxLhzcPraVwQsAkWM X-Spam-Note: CRM114 invocation failed X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.210.49 listed in list.dnswl.org] -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: linaro-kernel@lists.linaro.org, patches@linaro.org, Brian Swetland , linux-kernel@vger.kernel.org, =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= , John Stultz , linux-serial@vger.kernel.org, Colin Cross , kgdb-bugreport@lists.sourceforge.net, Thomas Gleixner , kernel-team@android.com, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org This command disables NMI-entry. If NMI source has been previously shared with a serial console ("debug port"), this effectively releases the port from KDB exclusive use, and makes the console available for normal use. Of course, NMI can be reenabled, enable_nmi modparam is used for that: echo 1 > /sys/module/kdb/parameters/enable_nmi Signed-off-by: Anton Vorontsov --- kernel/debug/kdb/kdb_main.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 31df170..9fadff1 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -2107,6 +2108,32 @@ static int kdb_dmesg(int argc, const char **argv) return 0; } #endif /* CONFIG_PRINTK */ + +/* Make sure we balance enable/disable calls, must disable first. */ +static atomic_t kdb_nmi_disabled; + +static int kdb_disable_nmi(int argc, const char *argv[]) +{ + if (atomic_read(&kdb_nmi_disabled)) + return 0; + atomic_set(&kdb_nmi_disabled, 1); + kgdb_enable_nmi(0); + return 0; +} + +static int kdb_param_enable_nmi(const char *val, const struct kernel_param *kp) +{ + if (!atomic_add_unless(&kdb_nmi_disabled, -1, 0)) + return -EINVAL; + kgdb_enable_nmi(1); + return 0; +} + +static const struct kernel_param_ops kdb_param_ops_enable_nmi = { + .set = kdb_param_enable_nmi, +}; +module_param_cb(enable_nmi, &kdb_param_ops_enable_nmi, NULL, 0600); + /* * kdb_cpu - This function implements the 'cpu' command. * cpu [] @@ -2851,6 +2878,8 @@ static void __init kdb_inittab(void) kdb_register_repeat("dmesg", kdb_dmesg, "[lines]", "Display syslog buffer", 0, KDB_REPEAT_NONE); #endif + kdb_register_repeat("disable_nmi", kdb_disable_nmi, "", + "Disable NMI entry to KDB", 0, KDB_REPEAT_NONE); kdb_register_repeat("defcmd", kdb_defcmd, "name \"usage\" \"help\"", "Define a set of commands, down to endefcmd", 0, KDB_REPEAT_NONE); kdb_register_repeat("kill", kdb_kill, "<-signal> ",