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Diffstat (limited to 'drivers/tty/serial/kgdboc.c')
-rw-r--r--drivers/tty/serial/kgdboc.c604
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..79b7db858
--- /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
+ * 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");