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David Alan Gilbert" , kgdb-bugreport@lists.sourceforge.net, Anton Vorontsov , Sumit Garg , linux-serial@vger.kernel.org, Douglas Anderson , Andy Shevchenko , Arnd Bergmann , Geert Uytterhoeven , Hugo Villeneuve , Jason Wessel , Nicolas Ferre , Niklas Schnelle , Robert Marko , linux-kernel@vger.kernel.org Subject: [PATCH 1/3] Revert "tty/serial: Add kgdb_nmi driver" Date: Wed, 29 Jan 2025 08:25:50 -0800 Message-ID: <20250129082535.1.Ia095eac1ae357f87d23e7af2206741f5d40788f1@changeid> X-Mailer: git-send-email 2.48.1.262.g85cc9f2d1e-goog In-Reply-To: <20250129162700.848018-1-dianders@chromium.org> References: <20250129162700.848018-1-dianders@chromium.org> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This reverts commit 0c57dfcc6c1d037243c2f8fbf62eab3633326ec0. The functionality was supoosed to be used by a later patch in the series that never landed [1]. Drop it. NOTE: part of functionality was already reverted by commit 39d0be87438a ("serial: kgdb_nmi: Remove unused knock code"). Also note that this revert is not a clean revert given code changes that have happened in the meantime. It's obvious that nobody is using this code since the two exposed functions (kgdb_register_nmi_console() and kgdb_unregister_nmi_console()) are both no-ops if "arch_kgdb_ops.enable_nmi" is not defined. No architectures define it. [1] https://lore.kernel.org/lkml/1348522080-32629-9-git-send-email-anton.vorontsov@linaro.org/ Signed-off-by: Douglas Anderson --- drivers/tty/serial/Kconfig | 19 --- drivers/tty/serial/Makefile | 1 - drivers/tty/serial/kgdb_nmi.c | 280 ---------------------------------- drivers/tty/serial/kgdboc.c | 8 - include/linux/kgdb.h | 8 - 5 files changed, 316 deletions(-) delete mode 100644 drivers/tty/serial/kgdb_nmi.c diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 976dae3bb1bb..f21cad6aaa47 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -179,25 +179,6 @@ 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 ($3#33). - This is because this console driver processes the input in NMI - context, and thus is able to intercept the magic sequence. - - Note that since the console interprets input and uses polling - communication methods, for things like PPP you still must fully - detach debugger port from the KGDB NMI (i.e. disable_nmi), and - use raw console. - - If unsure, say N. - config SERIAL_MESON tristate "Meson serial port support" depends on ARCH_MESON || COMPILE_TEST diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile index 6ff74f0a9530..3019260d9120 100644 --- a/drivers/tty/serial/Makefile +++ b/drivers/tty/serial/Makefile @@ -96,6 +96,5 @@ obj-$(CONFIG_SERIAL_ZS) += zs.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-$(CONFIG_KGDB_SERIAL_CONSOLE) += kgdboc.o obj-$(CONFIG_SERIAL_NUVOTON_MA35D1) += ma35d1_serial.o diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c deleted file mode 100644 index 2833708e369f..000000000000 --- a/drivers/tty/serial/kgdb_nmi.c +++ /dev/null @@ -1,280 +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 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; - -/* - * 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 unsigned int kgdb_nmi_tty_write_room(struct tty_struct *tty) -{ - /* Actually, we can handle any amount as we use polled writes. */ - return 2048; -} - -static ssize_t kgdb_nmi_tty_write(struct tty_struct *tty, const u8 *buf, - size_t 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 = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW); - if (IS_ERR(kgdb_nmi_tty_driver)) { - pr_err("%s: cannot allocate tty\n", __func__); - return PTR_ERR(kgdb_nmi_tty_driver); - } - 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->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: - tty_driver_kref_put(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; - - tty_unregister_driver(kgdb_nmi_tty_driver); - tty_driver_kref_put(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 58ea1e1391ce..85f6c5a76e0f 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -186,8 +186,6 @@ 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); } @@ -250,16 +248,10 @@ 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 51ef131e66b7..14739952698b 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -306,14 +306,6 @@ 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); -#else -static inline int kgdb_register_nmi_console(void) { return 0; } -static inline int kgdb_unregister_nmi_console(void) { return 0; } -#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;