From patchwork Thu Sep 20 18:30:58 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Anton Vorontsov X-Patchwork-Id: 1486841 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id 3C33CDF2D2 for ; Thu, 20 Sep 2012 18:36:01 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TElZH-00018X-HG; Thu, 20 Sep 2012 18:33:43 +0000 Received: from mail-pa0-f49.google.com ([209.85.220.49]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TElZC-000185-RN for linux-arm-kernel@lists.infradead.org; Thu, 20 Sep 2012 18:33:40 +0000 Received: by padbi5 with SMTP id bi5so131271pad.36 for ; Thu, 20 Sep 2012 11:33:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:content-transfer-encoding :in-reply-to:user-agent:x-gm-message-state; bh=8uggMOJLr4Xfz9uWu0iUtu1MOx77ugBl8CxJgoJ19uM=; b=otV4OoKyCMeeLk7cq0HGRIwXuoNHqkxMPYwDHSESikpuimRRHN929z3U0vcqKJQvq/ ubcRx1HUUve7CqYDBlqb0ij7knOpj7BUJ/sFXtqPXNNLhfQEWTbxwASUafn61yTUxoto VtuxXbMzawxWDKB3nbfGiOrTWJG1lOEunW076GtNSHpxzjcT52uh+a3JV0iRe518/BMH JWhZWyMg990VXucBh9aV3RVmrKRp1GTl3NsZ51kplfhQDjV24VJulwmkWJjjRk6AcxmC WWuKxvtWn7EvUOhurU/6iXqBZqZCJN65EV/A7pWryvvIthf4AGRYuZv03oDKfvLX+8+M XGIw== Received: by 10.68.134.97 with SMTP id pj1mr9065210pbb.55.1348166016515; Thu, 20 Sep 2012 11:33:36 -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 gv1sm3850353pbc.38.2012.09.20.11.33.34 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 20 Sep 2012 11:33:35 -0700 (PDT) Date: Thu, 20 Sep 2012 11:30:58 -0700 From: Anton Vorontsov To: Jason Wessel Subject: [PATCH updated 07/11] tty/serial: Add kgdb_nmi driver Message-ID: <20120920183058.GA1821@lizard> References: <20120919234003.GA24143@lizard> <1348098122-11041-7-git-send-email-anton.vorontsov@linaro.org> <505B20C6.5090308@windriver.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <505B20C6.5090308@windriver.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Gm-Message-State: ALoCoQnoWd7h2MJqN9EBfAMMlr9x+zYVUkDjOHsxQITCPjdS8V0lsgQ8Z0a62R38jGTOLR4g+Mrc 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 [209.85.220.49 listed in list.dnswl.org] -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Brian Swetland , linaro-kernel@lists.linaro.org, Russell King , patches@linaro.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Arve =?utf-8?B?SGrDuG5uZXbDpWc=?= , John Stultz , linux-serial@vger.kernel.org, Colin Cross , kgdb-bugreport@lists.sourceforge.net, Andrew Morton , kernel-team@android.com, Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Alan Cox 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: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org This special driver makes it possible to temporary use NMI debugger port as a normal console by issuing 'nmi_console' command (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 it is still better to fully detach debugger port from the KGDB NMI (i.e. disable_nmi), and use raw console. Usually, to enter the debugger one have to type the magic sequence, so initially the kernel will print the following prompt on the NMI debugger console: Type $3#33 to enter the debugger> For convenience, there is a kgdb_fiq.knock kernel command line option, when set to 0, this turns the special command to just a return key press, so the kernel will be printing this: Hit to enter the debugger> This is more convenient for long debugging sessions, although it makes nmi_console feature somewhat useless. And for the cases when NMI connected to a dedicated button, the knocking can be disabled altogether by setting kgdb_fiq.knock to -1. Suggested-by: Colin Cross Signed-off-by: Anton Vorontsov Acked-by: Alan Cox --- On Thu, Sep 20, 2012 at 08:57:26AM -0500, Jason Wessel wrote: > On 09/19/2012 06:41 PM, Anton Vorontsov wrote: > > This special driver makes it possible to temporary use NMI debugger port > > as a normal console by issuing 'nmi_console' command (assuming that the > > port is attached to KGDB). > > > > > The kgdb regression compiler also does checkpatch, so the "check patch > police" don't come chasing us let's get rid of this warning. This > comes with the disclaimer that I believe checkpatch is a bit overly > agressive in the first place. :-) Yup, I saw that warning, but decided to ignore as it was not legitimate. But sure, I'm fine either way, let's silence it. [....] > I have the kgdb regression builder running right now (it will be done in about 1 hour), and so far it picked up one new warning. > > drivers/tty/serial/kgdb_nmi.c: In function 'kgdb_nmi_poll_one_knock': > drivers/tty/serial/kgdb_nmi.c:161: warning: field width should have type 'int', but argument 4 has type 'size_t' Ouch, 64 bit. This is something I forgot to test, as I work mostly with 32 bit ARM builds. This small hunk fixes it up: - kgdb_nmi_knock ? magic : "", m, ""); + kgdb_nmi_knock ? magic : "", (int)m, ""); Thanks for catching this! These two fixups included in the patch down below. drivers/tty/serial/Kconfig | 19 ++ drivers/tty/serial/Makefile | 1 + drivers/tty/serial/kgdb_nmi.c | 402 ++++++++++++++++++++++++++++++++++++++++++ drivers/tty/serial/kgdboc.c | 9 + include/linux/kgdb.h | 10 ++ 5 files changed, 441 insertions(+) create mode 100644 drivers/tty/serial/kgdb_nmi.c diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 2a9659d..233fbaa 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -141,6 +141,25 @@ 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 ($3#33). + This is because this console driver processes the input in NMI + context, and thus is able to intercept the magic sequence. + + Note that since the console interprets input and uses polling + communication methods, for things like PPP you still must fully + detach debugger port from the KGDB NMI (i.e. disable_nmi), and + use raw console. + + If unsure, say N. + config SERIAL_KS8695 bool "Micrel KS8695 (Centaur) serial port support" depends on ARCH_KS8695 diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile index ce88667..4f694da 100644 --- a/drivers/tty/serial/Makefile +++ b/drivers/tty/serial/Makefile @@ -61,6 +61,7 @@ obj-$(CONFIG_SERIAL_MSM_HS) += msm_serial_hs.o obj-$(CONFIG_SERIAL_NETX) += netx-serial.o obj-$(CONFIG_SERIAL_OF_PLATFORM) += of_serial.o obj-$(CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL) += nwpserial.o +obj-$(CONFIG_SERIAL_KGDB_NMI) += kgdb_nmi.o obj-$(CONFIG_SERIAL_KS8695) += serial_ks8695.o obj-$(CONFIG_SERIAL_OMAP) += omap-serial.o obj-$(CONFIG_SERIAL_ALTERA_UART) += altera_uart.o diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c new file mode 100644 index 0000000..d185247 --- /dev/null +++ b/drivers/tty/serial/kgdb_nmi.c @@ -0,0 +1,402 @@ +/* + * KGDB NMI serial console + * + * Copyright 2010 Google, Inc. + * Arve Hjønnevåg + * Colin Cross + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#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 bool kgdb_nmi_tty_enabled; + +static void kgdb_nmi_console_write(struct console *co, const char *s, uint c) +{ + int i; + + if (!kgdb_nmi_tty_enabled || atomic_read(&kgdb_active) >= 0) + return; + + 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", + .write = kgdb_nmi_console_write, + .device = kgdb_nmi_console_device, + .flags = CON_PRINTBUFFER | CON_ANYTIME | CON_ENABLED, + .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 tasklet_struct tlet; + STRUCT_KFIFO(char, KGDB_NMI_FIFO_SIZE) fifo; +}; + +static struct kgdb_nmi_tty_priv *kgdb_nmi_port_to_priv(struct tty_port *port) +{ + return container_of(port, struct kgdb_nmi_tty_priv, port); +} + +/* + * Our debugging console is polled in a tasklet, so we'll check for input + * every tick. In HZ-less mode, we should program the next tick. We have + * to use the lowlevel stuff as no locks should be grabbed. + */ +#ifdef CONFIG_HIGH_RES_TIMERS +static void kgdb_tty_poke(void) +{ + tick_program_event(ktime_get(), 0); +} +#else +static inline void kgdb_tty_poke(void) {} +#endif + +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. Tasklet + * 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 = kgdb_nmi_port_to_priv(kgdb_nmi_port); + kfifo_in(&priv->fifo, &c, 1); + kgdb_tty_poke(); +} + +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 = 0; + + 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 = 1; + } else { + n = 0; + } + + if (kgdb_nmi_tty_enabled) { + 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 1; + + while (1) { + int ret; + + ret = kgdb_nmi_poll_one_knock(); + if (ret == NO_POLL_CHAR) + return 0; + else if (ret == 1) + break; + } + return 1; +} + +/* + * 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(unsigned long data) +{ + struct kgdb_nmi_tty_priv *priv = (void *)data; + struct tty_struct *tty; + char ch; + + tasklet_schedule(&priv->tlet); + + if (likely(!kgdb_nmi_tty_enabled || !kfifo_len(&priv->fifo))) + return; + + /* Port is there, but tty might be hung up, check. */ + tty = tty_port_tty_get(kgdb_nmi_port); + if (!tty) + return; + + while (kfifo_out(&priv->fifo, &ch, 1)) + tty_insert_flip_char(priv->port.tty, ch, TTY_NORMAL); + tty_flip_buffer_push(priv->port.tty); + + tty_kref_put(tty); +} + +static int kgdb_nmi_tty_activate(struct tty_port *port, struct tty_struct *tty) +{ + struct kgdb_nmi_tty_priv *priv = tty->driver_data; + + kgdb_nmi_port = port; + tasklet_schedule(&priv->tlet); + return 0; +} + +static void kgdb_nmi_tty_shutdown(struct tty_port *port) +{ + struct kgdb_nmi_tty_priv *priv = port->tty->driver_data; + + tasklet_kill(&priv->tlet); + 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); + tasklet_init(&priv->tlet, kgdb_nmi_tty_receiver, (unsigned long)priv); + 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: + 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; + kfree(priv); +} + +static int kgdb_nmi_tty_open(struct tty_struct *tty, struct file *file) +{ + struct kgdb_nmi_tty_priv *priv = tty->driver_data; + + return tty_port_open(&priv->port, tty, file); +} + +static void kgdb_nmi_tty_close(struct tty_struct *tty, struct file *file) +{ + struct kgdb_nmi_tty_priv *priv = tty->driver_data; + + 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, +}; + +static int kgdb_nmi_enable_console(int argc, const char *argv[]) +{ + kgdb_nmi_tty_enabled = !(argc == 1 && !strcmp(argv[1], "off")); + return 0; +} + +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; + } + + ret = kdb_register("nmi_console", kgdb_nmi_enable_console, "[off]", + "switch to Linux NMI console", 0); + if (ret) { + pr_err("%s: can't register kdb command: %d\n", __func__, ret); + goto err_kdb_reg; + } + + register_console(&kgdb_nmi_console); + arch_kgdb_ops.enable_nmi(1); + + return 0; +err_kdb_reg: + tty_unregister_driver(kgdb_nmi_tty_driver); +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); + + kdb_unregister("nmi_console"); + + 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 2b42a01..3f63d83 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -145,6 +145,8 @@ __setup("kgdboc=", kgdboc_option_setup); static void cleanup_kgdboc(void) { + if (kgdb_unregister_nmi_console()) + return; kgdboc_unregister_kbd(); if (configured == 1) kgdb_unregister_io_module(&kgdboc_io_ops); @@ -198,11 +200,18 @@ do_register: 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(); config[0] = 0; configured = 0; cleanup_kgdboc(); diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 7800cce..4dff0c6 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -286,6 +286,16 @@ extern struct kgdb_arch arch_kgdb_ops; extern unsigned long __weak 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 1; } +#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;