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[23.128.96.18]) by mx.google.com with ESMTP id dr11si10088434ejc.752.2020.07.21.05.11.18; Tue, 21 Jul 2020 05:11:19 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-serial-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=uf70pNth; spf=pass (google.com: domain of linux-serial-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-serial-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729913AbgGUMLS (ORCPT + 2 others); Tue, 21 Jul 2020 08:11:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728692AbgGUMLR (ORCPT ); Tue, 21 Jul 2020 08:11:17 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C16FFC061794 for ; Tue, 21 Jul 2020 05:11:17 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id 207so10643808pfu.3 for ; Tue, 21 Jul 2020 05:11:17 -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 :mime-version:content-transfer-encoding; bh=N4Vrr3RPHrWaZucTwZmFhL/vg7dtTdfGT3O+wG1Ixzw=; b=uf70pNthNkaG3TDajmNXQMzUZC357fX+gxRyGvjVoSt7QCQD+VlLfXEpUgB7chSAz6 FuBv3g5/v5cCY5sSHmWYxMWVGAcX/6yDmSmrb+oKCinGzeScKnAwpUZ1P+tEKAnRYfs7 Ja0AJZGiOm2s51IyFYTYMx8IDbE4GLdwb3civ6b5D0rKMcUzzulkbxVSEtYE6V95wGUm 7ha67V/Mww5u18Pk2tOxvaKnnyy6RxjLgpmbLlXCXHSMQpfu7ZV1qj97i1Nw1Xg1LfkO aay91kXJy6qnhoNRyr53om2Qs7jjUp+jzFAonpY8FVRxVINqOMymAN9HH4l0ENsgeQf6 mQbA== 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:mime-version:content-transfer-encoding; bh=N4Vrr3RPHrWaZucTwZmFhL/vg7dtTdfGT3O+wG1Ixzw=; b=MOtfAVgb6+d2ttj+snybhpi9zQkLef5/coZiLnciuWMQRljN87knFpUSPWt3/QhxHL aQMHICbNCOAOTNQp98zsOi208TssCJO7pSWvXPVPyS8jCsVNviq1wNcxc3GtOm6d0Dm+ rriRxPhF6JIVOgooKLSsDIy1fYo4CVN52OkfJbduNZ/kWnEXMutL1cejptWymxF5RyoT c+LTJBdXmAG3bZAK8Ih0i45sHWS/HEdp3Vtly12t000bmPRiyiBrLabqRJu8yxDpbsCY F9ItWD7FWfgh1wTt688DdA53ySVZOi8AtuIam1qD+HktmEdgnE968Z77NPVZj6ZxHCzR uE+A== X-Gm-Message-State: AOAM532F/ybcRo79NaXfrbb96hvNCc1nR9rnFUnFfTjVXbjrQIPcxTIP qiVGCfahkg5SP3zkQcUtEz+zsw== X-Received: by 2002:a65:63c8:: with SMTP id n8mr22380565pgv.232.1595333477168; Tue, 21 Jul 2020 05:11:17 -0700 (PDT) Received: from localhost.localdomain ([117.210.211.74]) by smtp.gmail.com with ESMTPSA id w9sm20601992pfq.178.2020.07.21.05.11.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Jul 2020 05:11:16 -0700 (PDT) From: Sumit Garg To: gregkh@linuxfoundation.org, daniel.thompson@linaro.org, dianders@chromium.org, linux-serial@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net Cc: jslaby@suse.com, linux@armlinux.org.uk, jason.wessel@windriver.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sumit Garg Subject: [RFC 5/5] serial: Remove KGDB NMI serial driver Date: Tue, 21 Jul 2020 17:40:13 +0530 Message-Id: <1595333413-30052-6-git-send-email-sumit.garg@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1595333413-30052-1-git-send-email-sumit.garg@linaro.org> References: <1595333413-30052-1-git-send-email-sumit.garg@linaro.org> MIME-Version: 1.0 Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org This driver provided a special ttyNMI0 port to enable NMI debugging capabilities for kgdb but it remained in silos with the serial core/drivers which made it a bit odd to enable using serial device interrupt and hence remained unused. But now with the serial core/drivers becoming NMI aware which in turn provides NMI debugging capabilities via magic sysrq, there is no specific reason to keep this special driver. So remove it instead. Signed-off-by: Sumit Garg --- drivers/tty/serial/Kconfig | 19 --- drivers/tty/serial/Makefile | 1 - drivers/tty/serial/kgdb_nmi.c | 383 ------------------------------------------ drivers/tty/serial/kgdboc.c | 8 - include/linux/kgdb.h | 10 -- 5 files changed, 421 deletions(-) delete mode 100644 drivers/tty/serial/kgdb_nmi.c -- 2.7.4 diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 780908d..625d283 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -176,25 +176,6 @@ config SERIAL_ATMEL_TTYAT Say Y if you have an external 8250/16C550 UART. If unsure, say N. -config SERIAL_KGDB_NMI - bool "Serial console over KGDB NMI debugger port" - depends on KGDB_SERIAL_CONSOLE - help - This special driver allows you to temporary use NMI debugger port - as a normal console (assuming that the port is attached to KGDB). - - Unlike KDB's disable_nmi command, with this driver you are always - able to go back to the debugger using KGDB escape sequence ($3#33). - This is because this console driver processes the input in NMI - context, and thus is able to intercept the magic sequence. - - Note that since the console interprets input and uses polling - communication methods, for things like PPP you still must fully - detach debugger port from the KGDB NMI (i.e. disable_nmi), and - use raw console. - - If unsure, say N. - config SERIAL_MESON tristate "Meson serial port support" depends on ARCH_MESON diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile index d056ee6..9ea6263 100644 --- a/drivers/tty/serial/Makefile +++ b/drivers/tty/serial/Makefile @@ -93,5 +93,4 @@ obj-$(CONFIG_SERIAL_SIFIVE) += sifive.o # GPIOLIB helpers for modem control lines obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o -obj-$(CONFIG_SERIAL_KGDB_NMI) += kgdb_nmi.o obj-$(CONFIG_KGDB_SERIAL_CONSOLE) += kgdboc.o diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c deleted file mode 100644 index 6004c0c..0000000 --- a/drivers/tty/serial/kgdb_nmi.c +++ /dev/null @@ -1,383 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * KGDB NMI serial console - * - * Copyright 2010 Google, Inc. - * Arve Hjønnevåg - * Colin Cross - * Copyright 2012 Linaro Ltd. - * Anton Vorontsov - */ - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -static int kgdb_nmi_knock = 1; -module_param_named(knock, kgdb_nmi_knock, int, 0600); -MODULE_PARM_DESC(knock, "if set to 1 (default), the special '$3#33' command " \ - "must be used to enter the debugger; when set to 0, " \ - "hitting return key is enough to enter the debugger; " \ - "when set to -1, the debugger is entered immediately " \ - "upon NMI"); - -static char *kgdb_nmi_magic = "$3#33"; -module_param_named(magic, kgdb_nmi_magic, charp, 0600); -MODULE_PARM_DESC(magic, "magic sequence to enter NMI debugger (default $3#33)"); - -static atomic_t kgdb_nmi_num_readers = ATOMIC_INIT(0); - -static int kgdb_nmi_console_setup(struct console *co, char *options) -{ - arch_kgdb_ops.enable_nmi(1); - - /* The NMI console uses the dbg_io_ops to issue console messages. To - * avoid duplicate messages during kdb sessions we must inform kdb's - * I/O utilities that messages sent to the console will automatically - * be displayed on the dbg_io. - */ - dbg_io_ops->cons = co; - - return 0; -} - -static void kgdb_nmi_console_write(struct console *co, const char *s, uint c) -{ - int i; - - for (i = 0; i < c; i++) - dbg_io_ops->write_char(s[i]); -} - -static struct tty_driver *kgdb_nmi_tty_driver; - -static struct tty_driver *kgdb_nmi_console_device(struct console *co, int *idx) -{ - *idx = co->index; - return kgdb_nmi_tty_driver; -} - -static struct console kgdb_nmi_console = { - .name = "ttyNMI", - .setup = kgdb_nmi_console_setup, - .write = kgdb_nmi_console_write, - .device = kgdb_nmi_console_device, - .flags = CON_PRINTBUFFER | CON_ANYTIME, - .index = -1, -}; - -/* - * This is usually the maximum rate on debug ports. We make fifo large enough - * to make copy-pasting to the terminal usable. - */ -#define KGDB_NMI_BAUD 115200 -#define KGDB_NMI_FIFO_SIZE roundup_pow_of_two(KGDB_NMI_BAUD / 8 / HZ) - -struct kgdb_nmi_tty_priv { - struct tty_port port; - struct timer_list timer; - STRUCT_KFIFO(char, KGDB_NMI_FIFO_SIZE) fifo; -}; - -static struct tty_port *kgdb_nmi_port; - -static void kgdb_tty_recv(int ch) -{ - struct kgdb_nmi_tty_priv *priv; - char c = ch; - - if (!kgdb_nmi_port || ch < 0) - return; - /* - * Can't use port->tty->driver_data as tty might be not there. Timer - * will check for tty and will get the ref, but here we don't have to - * do that, and actually, we can't: we're in NMI context, no locks are - * possible. - */ - priv = container_of(kgdb_nmi_port, struct kgdb_nmi_tty_priv, port); - kfifo_in(&priv->fifo, &c, 1); -} - -static int kgdb_nmi_poll_one_knock(void) -{ - static int n; - int c = -1; - const char *magic = kgdb_nmi_magic; - size_t m = strlen(magic); - bool printch = false; - - c = dbg_io_ops->read_char(); - if (c == NO_POLL_CHAR) - return c; - - if (!kgdb_nmi_knock && (c == '\r' || c == '\n')) { - return 1; - } else if (c == magic[n]) { - n = (n + 1) % m; - if (!n) - return 1; - printch = true; - } else { - n = 0; - } - - if (atomic_read(&kgdb_nmi_num_readers)) { - kgdb_tty_recv(c); - return 0; - } - - if (printch) { - kdb_printf("%c", c); - return 0; - } - - kdb_printf("\r%s %s to enter the debugger> %*s", - kgdb_nmi_knock ? "Type" : "Hit", - kgdb_nmi_knock ? magic : "", (int)m, ""); - while (m--) - kdb_printf("\b"); - return 0; -} - -/** - * kgdb_nmi_poll_knock - Check if it is time to enter the debugger - * - * "Serial ports are often noisy, especially when muxed over another port (we - * often use serial over the headset connector). Noise on the async command - * line just causes characters that are ignored, on a command line that blocked - * execution noise would be catastrophic." -- Colin Cross - * - * So, this function implements KGDB/KDB knocking on the serial line: we won't - * enter the debugger until we receive a known magic phrase (which is actually - * "$3#33", known as "escape to KDB" command. There is also a relaxed variant - * of knocking, i.e. just pressing the return key is enough to enter the - * debugger. And if knocking is disabled, the function always returns 1. - */ -bool kgdb_nmi_poll_knock(void) -{ - if (kgdb_nmi_knock < 0) - return true; - - while (1) { - int ret; - - ret = kgdb_nmi_poll_one_knock(); - if (ret == NO_POLL_CHAR) - return false; - else if (ret == 1) - break; - } - return true; -} - -/* - * The tasklet is cheap, it does not cause wakeups when reschedules itself, - * instead it waits for the next tick. - */ -static void kgdb_nmi_tty_receiver(struct timer_list *t) -{ - struct kgdb_nmi_tty_priv *priv = from_timer(priv, t, timer); - char ch; - - priv->timer.expires = jiffies + (HZ/100); - add_timer(&priv->timer); - - if (likely(!atomic_read(&kgdb_nmi_num_readers) || - !kfifo_len(&priv->fifo))) - return; - - while (kfifo_out(&priv->fifo, &ch, 1)) - tty_insert_flip_char(&priv->port, ch, TTY_NORMAL); - tty_flip_buffer_push(&priv->port); -} - -static int kgdb_nmi_tty_activate(struct tty_port *port, struct tty_struct *tty) -{ - struct kgdb_nmi_tty_priv *priv = - container_of(port, struct kgdb_nmi_tty_priv, port); - - kgdb_nmi_port = port; - priv->timer.expires = jiffies + (HZ/100); - add_timer(&priv->timer); - - return 0; -} - -static void kgdb_nmi_tty_shutdown(struct tty_port *port) -{ - struct kgdb_nmi_tty_priv *priv = - container_of(port, struct kgdb_nmi_tty_priv, port); - - del_timer(&priv->timer); - kgdb_nmi_port = NULL; -} - -static const struct tty_port_operations kgdb_nmi_tty_port_ops = { - .activate = kgdb_nmi_tty_activate, - .shutdown = kgdb_nmi_tty_shutdown, -}; - -static int kgdb_nmi_tty_install(struct tty_driver *drv, struct tty_struct *tty) -{ - struct kgdb_nmi_tty_priv *priv; - int ret; - - priv = kzalloc(sizeof(*priv), GFP_KERNEL); - if (!priv) - return -ENOMEM; - - INIT_KFIFO(priv->fifo); - timer_setup(&priv->timer, kgdb_nmi_tty_receiver, 0); - tty_port_init(&priv->port); - priv->port.ops = &kgdb_nmi_tty_port_ops; - tty->driver_data = priv; - - ret = tty_port_install(&priv->port, drv, tty); - if (ret) { - pr_err("%s: can't install tty port: %d\n", __func__, ret); - goto err; - } - return 0; -err: - tty_port_destroy(&priv->port); - kfree(priv); - return ret; -} - -static void kgdb_nmi_tty_cleanup(struct tty_struct *tty) -{ - struct kgdb_nmi_tty_priv *priv = tty->driver_data; - - tty->driver_data = NULL; - tty_port_destroy(&priv->port); - kfree(priv); -} - -static int kgdb_nmi_tty_open(struct tty_struct *tty, struct file *file) -{ - struct kgdb_nmi_tty_priv *priv = tty->driver_data; - unsigned int mode = file->f_flags & O_ACCMODE; - int ret; - - ret = tty_port_open(&priv->port, tty, file); - if (!ret && (mode == O_RDONLY || mode == O_RDWR)) - atomic_inc(&kgdb_nmi_num_readers); - - return ret; -} - -static void kgdb_nmi_tty_close(struct tty_struct *tty, struct file *file) -{ - struct kgdb_nmi_tty_priv *priv = tty->driver_data; - unsigned int mode = file->f_flags & O_ACCMODE; - - if (mode == O_RDONLY || mode == O_RDWR) - atomic_dec(&kgdb_nmi_num_readers); - - tty_port_close(&priv->port, tty, file); -} - -static void kgdb_nmi_tty_hangup(struct tty_struct *tty) -{ - struct kgdb_nmi_tty_priv *priv = tty->driver_data; - - tty_port_hangup(&priv->port); -} - -static int kgdb_nmi_tty_write_room(struct tty_struct *tty) -{ - /* Actually, we can handle any amount as we use polled writes. */ - return 2048; -} - -static int kgdb_nmi_tty_write(struct tty_struct *tty, const unchar *buf, int c) -{ - int i; - - for (i = 0; i < c; i++) - dbg_io_ops->write_char(buf[i]); - return c; -} - -static const struct tty_operations kgdb_nmi_tty_ops = { - .open = kgdb_nmi_tty_open, - .close = kgdb_nmi_tty_close, - .install = kgdb_nmi_tty_install, - .cleanup = kgdb_nmi_tty_cleanup, - .hangup = kgdb_nmi_tty_hangup, - .write_room = kgdb_nmi_tty_write_room, - .write = kgdb_nmi_tty_write, -}; - -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__); - return -ENOMEM; - } - kgdb_nmi_tty_driver->driver_name = "ttyNMI"; - kgdb_nmi_tty_driver->name = "ttyNMI"; - kgdb_nmi_tty_driver->num = 1; - kgdb_nmi_tty_driver->type = TTY_DRIVER_TYPE_SERIAL; - kgdb_nmi_tty_driver->subtype = SERIAL_TYPE_NORMAL; - kgdb_nmi_tty_driver->flags = TTY_DRIVER_REAL_RAW; - kgdb_nmi_tty_driver->init_termios = tty_std_termios; - tty_termios_encode_baud_rate(&kgdb_nmi_tty_driver->init_termios, - KGDB_NMI_BAUD, KGDB_NMI_BAUD); - tty_set_operations(kgdb_nmi_tty_driver, &kgdb_nmi_tty_ops); - - ret = tty_register_driver(kgdb_nmi_tty_driver); - if (ret) { - pr_err("%s: can't register tty driver: %d\n", __func__, ret); - goto err_drv_reg; - } - - register_console(&kgdb_nmi_console); - - return 0; -err_drv_reg: - put_tty_driver(kgdb_nmi_tty_driver); - return ret; -} -EXPORT_SYMBOL_GPL(kgdb_register_nmi_console); - -int kgdb_unregister_nmi_console(void) -{ - int ret; - - if (!arch_kgdb_ops.enable_nmi) - return 0; - arch_kgdb_ops.enable_nmi(0); - - ret = unregister_console(&kgdb_nmi_console); - if (ret) - return ret; - - ret = tty_unregister_driver(kgdb_nmi_tty_driver); - if (ret) - return ret; - put_tty_driver(kgdb_nmi_tty_driver); - - return 0; -} -EXPORT_SYMBOL_GPL(kgdb_unregister_nmi_console); diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index 84ffede..e959e72 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -158,8 +158,6 @@ static void cleanup_kgdboc(void) if (configured != 1) return; - if (kgdb_unregister_nmi_console()) - return; kgdboc_unregister_kbd(); kgdb_unregister_io_module(&kgdboc_io_ops); } @@ -210,16 +208,10 @@ static int configure_kgdboc(void) if (err) goto noconfig; - err = kgdb_register_nmi_console(); - if (err) - goto nmi_con_failed; - configured = 1; return 0; -nmi_con_failed: - kgdb_unregister_io_module(&kgdboc_io_ops); noconfig: kgdboc_unregister_kbd(); configured = 0; diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 529116b..2e8c5de 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -294,16 +294,6 @@ extern const struct kgdb_arch arch_kgdb_ops; extern unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs); -#ifdef CONFIG_SERIAL_KGDB_NMI -extern int kgdb_register_nmi_console(void); -extern int kgdb_unregister_nmi_console(void); -extern bool kgdb_nmi_poll_knock(void); -#else -static inline int kgdb_register_nmi_console(void) { return 0; } -static inline int kgdb_unregister_nmi_console(void) { return 0; } -static inline bool kgdb_nmi_poll_knock(void) { return true; } -#endif - extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops); extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops); extern struct kgdb_io *dbg_io_ops;