diff options
Diffstat (limited to 'drivers/tty/serial/kgdboc.c')
| -rw-r--r-- | drivers/tty/serial/kgdboc.c | 604 |
1 files changed, 604 insertions, 0 deletions
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c new file mode 100644 index 000000000..7aa37be32 --- /dev/null +++ b/drivers/tty/serial/kgdboc.c @@ -0,0 +1,604 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Based on the same principle as kgdboe using the NETPOLL api, this + * driver uses a console polling api to implement a gdb serial inteface + * which is multiplexed on a console port. + * + * Maintainer: Jason Wessel <jason.wessel@windriver.com> + * + * 2007-2008 (c) Jason Wessel - Wind River Systems, Inc. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/ctype.h> +#include <linux/kgdb.h> +#include <linux/kdb.h> +#include <linux/tty.h> +#include <linux/console.h> +#include <linux/vt_kern.h> +#include <linux/input.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/serial_core.h> + +#define MAX_CONFIG_LEN 40 + +static struct kgdb_io kgdboc_io_ops; + +/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */ +static int configured = -1; +static DEFINE_MUTEX(config_mutex); + +static char config[MAX_CONFIG_LEN]; +static struct kparam_string kps = { + .string = config, + .maxlen = MAX_CONFIG_LEN, +}; + +static int kgdboc_use_kms; /* 1 if we use kernel mode switching */ +static struct tty_driver *kgdb_tty_driver; +static int kgdb_tty_line; + +static struct platform_device *kgdboc_pdev; + +#if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) +static struct kgdb_io kgdboc_earlycon_io_ops; +static int (*earlycon_orig_exit)(struct console *con); +#endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */ + +#ifdef CONFIG_KDB_KEYBOARD +static int kgdboc_reset_connect(struct input_handler *handler, + struct input_dev *dev, + const struct input_device_id *id) +{ + input_reset_device(dev); + + /* Return an error - we do not want to bind, just to reset */ + return -ENODEV; +} + +static void kgdboc_reset_disconnect(struct input_handle *handle) +{ + /* We do not expect anyone to actually bind to us */ + BUG(); +} + +static const struct input_device_id kgdboc_reset_ids[] = { + { + .flags = INPUT_DEVICE_ID_MATCH_EVBIT, + .evbit = { BIT_MASK(EV_KEY) }, + }, + { } +}; + +static struct input_handler kgdboc_reset_handler = { + .connect = kgdboc_reset_connect, + .disconnect = kgdboc_reset_disconnect, + .name = "kgdboc_reset", + .id_table = kgdboc_reset_ids, +}; + +static DEFINE_MUTEX(kgdboc_reset_mutex); + +static void kgdboc_restore_input_helper(struct work_struct *dummy) +{ + /* + * We need to take a mutex to prevent several instances of + * this work running on different CPUs so they don't try + * to register again already registered handler. + */ + mutex_lock(&kgdboc_reset_mutex); + + if (input_register_handler(&kgdboc_reset_handler) == 0) + input_unregister_handler(&kgdboc_reset_handler); + + mutex_unlock(&kgdboc_reset_mutex); +} + +static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper); + +static void kgdboc_restore_input(void) +{ + if (likely(system_state == SYSTEM_RUNNING)) + schedule_work(&kgdboc_restore_input_work); +} + +static int kgdboc_register_kbd(char **cptr) +{ + if (strncmp(*cptr, "kbd", 3) == 0 || + strncmp(*cptr, "kdb", 3) == 0) { + if (kdb_poll_idx < KDB_POLL_FUNC_MAX) { + kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char; + kdb_poll_idx++; + if (cptr[0][3] == ',') + *cptr += 4; + else + return 1; + } + } + return 0; +} + +static void kgdboc_unregister_kbd(void) +{ + int i; + + for (i = 0; i < kdb_poll_idx; i++) { + if (kdb_poll_funcs[i] == kdb_get_kbd_char) { + kdb_poll_idx--; + kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx]; + kdb_poll_funcs[kdb_poll_idx] = NULL; + i--; + } + } + flush_work(&kgdboc_restore_input_work); +} +#else /* ! CONFIG_KDB_KEYBOARD */ +#define kgdboc_register_kbd(x) 0 +#define kgdboc_unregister_kbd() +#define kgdboc_restore_input() +#endif /* ! CONFIG_KDB_KEYBOARD */ + +#if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) +static void cleanup_earlycon(void) +{ + if (kgdboc_earlycon_io_ops.cons) + kgdb_unregister_io_module(&kgdboc_earlycon_io_ops); +} +#else /* !IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */ +static inline void cleanup_earlycon(void) { } +#endif /* !IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */ + +static void cleanup_kgdboc(void) +{ + cleanup_earlycon(); + + if (configured != 1) + return; + + if (kgdb_unregister_nmi_console()) + return; + kgdboc_unregister_kbd(); + kgdb_unregister_io_module(&kgdboc_io_ops); +} + +static int configure_kgdboc(void) +{ + struct tty_driver *p; + int tty_line = 0; + int err = -ENODEV; + char *cptr = config; + struct console *cons; + + if (!strlen(config) || isspace(config[0])) { + err = 0; + goto noconfig; + } + + kgdboc_io_ops.cons = NULL; + kgdb_tty_driver = NULL; + + kgdboc_use_kms = 0; + if (strncmp(cptr, "kms,", 4) == 0) { + cptr += 4; + kgdboc_use_kms = 1; + } + + if (kgdboc_register_kbd(&cptr)) + goto do_register; + + p = tty_find_polling_driver(cptr, &tty_line); + if (!p) + goto noconfig; + + for_each_console(cons) { + int idx; + if (cons->device && cons->device(cons, &idx) == p && + idx == tty_line) { + kgdboc_io_ops.cons = cons; + break; + } + } + + kgdb_tty_driver = p; + kgdb_tty_line = tty_line; + +do_register: + err = kgdb_register_io_module(&kgdboc_io_ops); + 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; + + return err; +} + +static int kgdboc_probe(struct platform_device *pdev) +{ + int ret = 0; + + mutex_lock(&config_mutex); + if (configured != 1) { + ret = configure_kgdboc(); + + /* Convert "no device" to "defer" so we'll keep trying */ + if (ret == -ENODEV) + ret = -EPROBE_DEFER; + } + mutex_unlock(&config_mutex); + + return ret; +} + +static struct platform_driver kgdboc_platform_driver = { + .probe = kgdboc_probe, + .driver = { + .name = "kgdboc", + .suppress_bind_attrs = true, + }, +}; + +static int __init init_kgdboc(void) +{ + int ret; + + /* + * kgdboc is a little bit of an odd "platform_driver". It can be + * up and running long before the platform_driver object is + * created and thus doesn't actually store anything in it. There's + * only one instance of kgdb so anything is stored as global state. + * The platform_driver is only created so that we can leverage the + * kernel's mechanisms (like -EPROBE_DEFER) to call us when our + * underlying tty is ready. Here we init our platform driver and + * then create the single kgdboc instance. + */ + ret = platform_driver_register(&kgdboc_platform_driver); + if (ret) + return ret; + + kgdboc_pdev = platform_device_alloc("kgdboc", PLATFORM_DEVID_NONE); + if (!kgdboc_pdev) { + ret = -ENOMEM; + goto err_did_register; + } + + ret = platform_device_add(kgdboc_pdev); + if (!ret) + return 0; + + platform_device_put(kgdboc_pdev); + +err_did_register: + platform_driver_unregister(&kgdboc_platform_driver); + return ret; +} + +static void exit_kgdboc(void) +{ + mutex_lock(&config_mutex); + cleanup_kgdboc(); + mutex_unlock(&config_mutex); + + platform_device_unregister(kgdboc_pdev); + platform_driver_unregister(&kgdboc_platform_driver); +} + +static int kgdboc_get_char(void) +{ + if (!kgdb_tty_driver) + return -1; + return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver, + kgdb_tty_line); +} + +static void kgdboc_put_char(u8 chr) +{ + if (!kgdb_tty_driver) + return; + kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver, + kgdb_tty_line, chr); +} + +static int param_set_kgdboc_var(const char *kmessage, + const struct kernel_param *kp) +{ + size_t len = strlen(kmessage); + int ret = 0; + + if (len >= MAX_CONFIG_LEN) { + pr_err("config string too long\n"); + return -ENOSPC; + } + + if (kgdb_connected) { + pr_err("Cannot reconfigure while KGDB is connected.\n"); + return -EBUSY; + } + + mutex_lock(&config_mutex); + + strcpy(config, kmessage); + /* Chop out \n char as a result of echo */ + if (len && config[len - 1] == '\n') + config[len - 1] = '\0'; + + if (configured == 1) + cleanup_kgdboc(); + + /* + * Configure with the new params as long as init already ran. + * Note that we can get called before init if someone loads us + * with "modprobe kgdboc kgdboc=..." or if they happen to use + * the odd syntax of "kgdboc.kgdboc=..." on the kernel command. + */ + if (configured >= 0) + ret = configure_kgdboc(); + + /* + * If we couldn't configure then clear out the config. Note that + * specifying an invalid config on the kernel command line vs. + * through sysfs have slightly different behaviors. If we fail + * to configure what was specified on the kernel command line + * we'll leave it in the 'config' and return -EPROBE_DEFER from + * our probe. When specified through sysfs userspace is + * responsible for loading the tty driver before setting up. + */ + if (ret) + config[0] = '\0'; + + mutex_unlock(&config_mutex); + + return ret; +} + +static int dbg_restore_graphics; + +static void kgdboc_pre_exp_handler(void) +{ + if (!dbg_restore_graphics && kgdboc_use_kms) { + dbg_restore_graphics = 1; + con_debug_enter(vc_cons[fg_console].d); + } + /* Increment the module count when the debugger is active */ + if (!kgdb_connected) + try_module_get(THIS_MODULE); +} + +static void kgdboc_post_exp_handler(void) +{ + /* decrement the module count when the debugger detaches */ + if (!kgdb_connected) + module_put(THIS_MODULE); + if (kgdboc_use_kms && dbg_restore_graphics) { + dbg_restore_graphics = 0; + con_debug_leave(); + } + kgdboc_restore_input(); +} + +static struct kgdb_io kgdboc_io_ops = { + .name = "kgdboc", + .read_char = kgdboc_get_char, + .write_char = kgdboc_put_char, + .pre_exception = kgdboc_pre_exp_handler, + .post_exception = kgdboc_post_exp_handler, +}; + +#if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) +static int kgdboc_option_setup(char *opt) +{ + if (!opt) { + pr_err("config string not provided\n"); + return 1; + } + + if (strlen(opt) >= MAX_CONFIG_LEN) { + pr_err("config string too long\n"); + return 1; + } + strcpy(config, opt); + + return 1; +} + +__setup("kgdboc=", kgdboc_option_setup); + + +/* This is only available if kgdboc is a built in for early debugging */ +static int __init kgdboc_early_init(char *opt) +{ + kgdboc_option_setup(opt); + configure_kgdboc(); + return 0; +} + +early_param("ekgdboc", kgdboc_early_init); + +static int kgdboc_earlycon_get_char(void) +{ + char c; + + if (!kgdboc_earlycon_io_ops.cons->read(kgdboc_earlycon_io_ops.cons, + &c, 1)) + return NO_POLL_CHAR; + + return c; +} + +static void kgdboc_earlycon_put_char(u8 chr) +{ + kgdboc_earlycon_io_ops.cons->write(kgdboc_earlycon_io_ops.cons, &chr, + 1); +} + +static void kgdboc_earlycon_pre_exp_handler(void) +{ + struct console *con; + static bool already_warned; + + if (already_warned) + return; + + /* + * When the first normal console comes up the kernel will take all + * the boot consoles out of the list. Really, we should stop using + * the boot console when it does that but until a TTY is registered + * we have no other choice so we keep using it. Since not all + * serial drivers might be OK with this, print a warning once per + * boot if we detect this case. + */ + for_each_console(con) + if (con == kgdboc_earlycon_io_ops.cons) + return; + + already_warned = true; + pr_warn("kgdboc_earlycon is still using bootconsole\n"); +} + +static int kgdboc_earlycon_deferred_exit(struct console *con) +{ + /* + * If we get here it means the boot console is going away but we + * don't yet have a suitable replacement. Don't pass through to + * the original exit routine. We'll call it later in our deinit() + * function. For now, restore the original exit() function pointer + * as a sentinal that we've hit this point. + */ + con->exit = earlycon_orig_exit; + + return 0; +} + +static void kgdboc_earlycon_deinit(void) +{ + if (!kgdboc_earlycon_io_ops.cons) + return; + + if (kgdboc_earlycon_io_ops.cons->exit == kgdboc_earlycon_deferred_exit) + /* + * kgdboc_earlycon is exiting but original boot console exit + * was never called (AKA kgdboc_earlycon_deferred_exit() + * didn't ever run). Undo our trap. + */ + kgdboc_earlycon_io_ops.cons->exit = earlycon_orig_exit; + else if (kgdboc_earlycon_io_ops.cons->exit) + /* + * We skipped calling the exit() routine so we could try to + * keep using the boot console even after it went away. We're + * finally done so call the function now. + */ + kgdboc_earlycon_io_ops.cons->exit(kgdboc_earlycon_io_ops.cons); + + kgdboc_earlycon_io_ops.cons = NULL; +} + +static struct kgdb_io kgdboc_earlycon_io_ops = { + .name = "kgdboc_earlycon", + .read_char = kgdboc_earlycon_get_char, + .write_char = kgdboc_earlycon_put_char, + .pre_exception = kgdboc_earlycon_pre_exp_handler, + .deinit = kgdboc_earlycon_deinit, +}; + +#define MAX_CONSOLE_NAME_LEN (sizeof((struct console *) 0)->name) +static char kgdboc_earlycon_param[MAX_CONSOLE_NAME_LEN] __initdata; +static bool kgdboc_earlycon_late_enable __initdata; + +static int __init kgdboc_earlycon_init(char *opt) +{ + struct console *con; + + kdb_init(KDB_INIT_EARLY); + + /* + * Look for a matching console, or if the name was left blank just + * pick the first one we find. + */ + console_lock(); + for_each_console(con) { + if (con->write && con->read && + (con->flags & (CON_BOOT | CON_ENABLED)) && + (!opt || !opt[0] || strcmp(con->name, opt) == 0)) + break; + } + + if (!con) { + /* + * Both earlycon and kgdboc_earlycon are initialized during + * early parameter parsing. We cannot guarantee earlycon gets + * in first and, in any case, on ACPI systems earlycon may + * defer its own initialization (usually to somewhere within + * setup_arch() ). To cope with either of these situations + * we can defer our own initialization to a little later in + * the boot. + */ + if (!kgdboc_earlycon_late_enable) { + pr_info("No suitable earlycon yet, will try later\n"); + if (opt) + strscpy(kgdboc_earlycon_param, opt, + sizeof(kgdboc_earlycon_param)); + kgdboc_earlycon_late_enable = true; + } else { + pr_info("Couldn't find kgdb earlycon\n"); + } + goto unlock; + } + + kgdboc_earlycon_io_ops.cons = con; + pr_info("Going to register kgdb with earlycon '%s'\n", con->name); + if (kgdb_register_io_module(&kgdboc_earlycon_io_ops) != 0) { + kgdboc_earlycon_io_ops.cons = NULL; + pr_info("Failed to register kgdb with earlycon\n"); + } else { + /* Trap exit so we can keep earlycon longer if needed. */ + earlycon_orig_exit = con->exit; + con->exit = kgdboc_earlycon_deferred_exit; + } + +unlock: + console_unlock(); + + /* Non-zero means malformed option so we always return zero */ + return 0; +} + +early_param("kgdboc_earlycon", kgdboc_earlycon_init); + +/* + * This is only intended for the late adoption of an early console. + * + * It is not a reliable way to adopt regular consoles because we can not + * control what order console initcalls are made and, in any case, many + * regular consoles are registered much later in the boot process than + * the console initcalls! + */ +static int __init kgdboc_earlycon_late_init(void) +{ + if (kgdboc_earlycon_late_enable) + kgdboc_earlycon_init(kgdboc_earlycon_param); + return 0; +} +console_initcall(kgdboc_earlycon_late_init); + +#endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */ + +module_init(init_kgdboc); +module_exit(exit_kgdboc); +module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644); +MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]"); +MODULE_DESCRIPTION("KGDB Console TTY Driver"); +MODULE_LICENSE("GPL"); |