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=-10.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 E0B7AC433E0 for ; Mon, 22 Jun 2020 14:27:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B654020738 for ; Mon, 22 Jun 2020 14:27:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="QOeLXcXX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729795AbgFVO1p (ORCPT ); Mon, 22 Jun 2020 10:27:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729783AbgFVO1k (ORCPT ); Mon, 22 Jun 2020 10:27:40 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FB4CC061795 for ; Mon, 22 Jun 2020 07:27:40 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id i4so8711908pjd.0 for ; Mon, 22 Jun 2020 07:27:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=sjUQXgLs8QLSZt9fRiSIf9rP+l/zfeDDFs4yVtYk7Z0=; b=QOeLXcXXYJY7Mbx/0GKxWfojZNvqp1+/iUKrhHvJJPT9TVW7hdHXE2t9l97MfMSFpN a08ODnr/u8hVAu7RVgm3nwaohgTk6yIAfdCRoM5WfyRsqxQHCEGEzi9wTA/yKOQSDDTn EspPlVmFhi6LGov/zu0zVQxHn0TORwdNIp4Tz25YBXpANqqkhTFuF4GxAxBipD+4hDqG jmvq8KHWY56pQ4Uhc3UmRVKr91Ozy+VR2DUlvgYbGewgO3jRkY/Dp81cKfOw8z4F75Dm Z8nwP0kHFAnNAqtxxXXSBop65W6O3MFJ//0g5Mpc6ZSBKBujqa7snPffto/Uxw5BV9qX S9qA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=sjUQXgLs8QLSZt9fRiSIf9rP+l/zfeDDFs4yVtYk7Z0=; b=Th7xlWp27r1ELps/z8z96d5cDH4XBpoI6hxueVL6BZ1T8uBmngtfC5rxaLVl9F1ZDh OK8JU2SsQ8cx5v684APUw84itP1qP3E0h6Sv05p4uQwMnsTwjm13cilz3wdYoP3yuSzF 5y2t+K2SQ/jCGZ1IkidbG1tyKwDo24CAnf+7BIYgGS+J0Tpatm/qXlkRFd5A2rERYt2s ou3CcJWf6oNS+eW2vK1tlThfd5poXb6b/BF2OzwSJls/dMVwfW+GI17Z2+ZmMvBbQK1z cXcWuDJVt7OTv9xOgKB8uCdjMvhc6jSRp/TpkI6mveaJs+eyAp+2DLvkxqV6vXKeGIzn Qj3g== X-Gm-Message-State: AOAM5316NY0KZ4gKE6/dceRfe7+IY+9hXKqNAE2N/AAb9Jv6X5yrPfBO bCDJSSzuaSKhgYUg+p6mjppzEA== X-Google-Smtp-Source: ABdhPJzpaCxkbO/21akB31Cg1TWuLDrphNwsB5izjnAOPjR2mgcdxwifka4NWh+oyQbNDK0xDtgcng== X-Received: by 2002:a17:90a:d485:: with SMTP id s5mr17596432pju.61.1592836060022; Mon, 22 Jun 2020 07:27:40 -0700 (PDT) Received: from localhost.localdomain ([117.252.67.186]) by smtp.gmail.com with ESMTPSA id d6sm14547939pjh.5.2020.06.22.07.27.35 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 Jun 2020 07:27:39 -0700 (PDT) From: Sumit Garg To: kgdb-bugreport@lists.sourceforge.net, linux-serial@vger.kernel.org Cc: gregkh@linuxfoundation.org, daniel.thompson@linaro.org, jason.wessel@windriver.com, dianders@chromium.org, jslaby@suse.com, linux@armlinux.org.uk, linux-kernel@vger.kernel.org, Sumit Garg Subject: [PATCH 4/7] serial: kgdb_nmi: Add support for interrupt based fallback Date: Mon, 22 Jun 2020 19:56:21 +0530 Message-Id: <1592835984-28613-5-git-send-email-sumit.garg@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1592835984-28613-1-git-send-email-sumit.garg@linaro.org> References: <1592835984-28613-1-git-send-email-sumit.garg@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Thompson Add a generic NMI fallback to support kgdb NMI console feature which can be overridden by arch specific implementation. This common fallback mechanism utilizes kgdb IO based interrupt in order to support entry into kgdb if a user types in kgdb_nmi_magic sequence. So during NMI console init, NMI handler is installed corresponding to kgdb IO based NMI which is invoked when a character is pending and that can be cleared by calling @read_char until it returns NO_POLL_CHAR. Signed-off-by: Daniel Thompson Co-developed-by: Sumit Garg Signed-off-by: Sumit Garg --- drivers/tty/serial/kgdb_nmi.c | 47 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 40 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c index b32c6b1..2580f39 100644 --- a/drivers/tty/serial/kgdb_nmi.c +++ b/drivers/tty/serial/kgdb_nmi.c @@ -42,9 +42,46 @@ MODULE_PARM_DESC(magic, "magic sequence to enter NMI debugger (default $3#33)"); static atomic_t kgdb_nmi_num_readers = ATOMIC_INIT(0); static struct console *orig_dbg_cons; +static int kgdb_nmi_poll_one_knock(void); + +static irqreturn_t kgdb_handle_nmi(int irq, void *dev_id) +{ + int ret; + + if (kgdb_nmi_knock < 0) { + kgdb_breakpoint(); + return IRQ_HANDLED; + } + + ret = kgdb_nmi_poll_one_knock(); + if (ret == NO_POLL_CHAR) + return IRQ_NONE; + + while (ret != 1) { + ret = kgdb_nmi_poll_one_knock(); + if (ret == NO_POLL_CHAR) + return IRQ_HANDLED; + } + + kgdb_breakpoint(); + return IRQ_HANDLED; +} + static int kgdb_nmi_console_setup(struct console *co, char *options) { - arch_kgdb_ops.enable_nmi(1); + int res; + + if (arch_kgdb_ops.enable_nmi) { + arch_kgdb_ops.enable_nmi(1); + } else if (dbg_io_ops->request_nmi) { + res = dbg_io_ops->request_nmi(kgdb_handle_nmi, co); + if (res) { + pr_err("ttyNMI0: Cannot request nmi/irq\n"); + return res; + } + } else { + return -ENODEV; + } /* The NMI console uses the dbg_io_ops to issue console messages. To * avoid duplicate messages during kdb sessions we must inform kdb's @@ -328,9 +365,6 @@ int kgdb_register_nmi_console(void) { int ret; - if (!arch_kgdb_ops.enable_nmi) - return 0; - kgdb_nmi_tty_driver = alloc_tty_driver(1); if (!kgdb_nmi_tty_driver) { pr_err("%s: cannot allocate tty\n", __func__); @@ -380,9 +414,8 @@ int kgdb_unregister_nmi_console(void) { int ret; - if (!arch_kgdb_ops.enable_nmi) - return 0; - arch_kgdb_ops.enable_nmi(0); + if (arch_kgdb_ops.enable_nmi) + arch_kgdb_ops.enable_nmi(0); ret = unregister_console(&kgdb_nmi_console); if (ret) -- 2.7.4