diff options
| -rw-r--r-- | drivers/tty/serial/kgdboc.c | 136 | ||||
| -rw-r--r-- | include/linux/kgdb.h | 4 | ||||
| -rw-r--r-- | kernel/debug/debug_core.c | 22 |
3 files changed, 158 insertions, 4 deletions
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index a260ecd13e8f..34b5e91dd245 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -21,6 +21,7 @@ #include <linux/input.h> #include <linux/module.h> #include <linux/platform_device.h> +#include <linux/serial_core.h> #define MAX_CONFIG_LEN 40 @@ -42,6 +43,10 @@ static int kgdb_tty_line; static struct platform_device *kgdboc_pdev; +static struct kgdb_io kgdboc_earlycon_io_ops; +static struct console *earlycon; +static int (*earlycon_orig_exit)(struct console *con); + #ifdef CONFIG_KDB_KEYBOARD static int kgdboc_reset_connect(struct input_handler *handler, struct input_dev *dev, @@ -137,6 +142,9 @@ static void kgdboc_unregister_kbd(void) static void cleanup_kgdboc(void) { + if (earlycon) + kgdb_unregister_io_module(&kgdboc_earlycon_io_ops); + if (configured != 1) return; @@ -409,6 +417,134 @@ static int __init kgdboc_early_init(char *opt) early_param("ekgdboc", kgdboc_early_init); +static int kgdboc_earlycon_get_char(void) +{ + char c; + + if (!earlycon->read(earlycon, &c, 1)) + return NO_POLL_CHAR; + + return c; +} + +static void kgdboc_earlycon_put_char(u8 chr) +{ + earlycon->write(earlycon, &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 == earlycon) + 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 (!earlycon) + return; + + if (earlycon->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. + */ + earlycon->exit = earlycon_orig_exit; + else if (earlycon->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. + */ + earlycon->exit(earlycon); + + earlycon = 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, + .is_console = true, +}; + +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) { + pr_info("Couldn't find kgdb earlycon\n"); + goto unlock; + } + + earlycon = con; + pr_info("Going to register kgdb with earlycon '%s'\n", con->name); + if (kgdb_register_io_module(&kgdboc_earlycon_io_ops) != 0) { + earlycon = 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); + module_init(init_kgdboc); module_exit(exit_kgdboc); module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644); diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index c2caee08e418..c62d76478adc 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -269,6 +269,9 @@ struct kgdb_arch { * @write_char: Pointer to a function that will write one char. * @flush: Pointer to a function that will flush any pending writes. * @init: Pointer to a function that will initialize the device. + * @deinit: Pointer to a function that will deinit the device. Implies that + * this I/O driver is temporary and expects to be replaced. Called when + * an I/O driver is replaced or explicitly unregistered. * @pre_exception: Pointer to a function that will do any prep work for * the I/O driver. * @post_exception: Pointer to a function that will do any cleanup work @@ -282,6 +285,7 @@ struct kgdb_io { void (*write_char) (u8); void (*flush) (void); int (*init) (void); + void (*deinit) (void); void (*pre_exception) (void); void (*post_exception) (void); int is_console; diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index e2d67b163fb6..4d59aa907fdc 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -1073,15 +1073,23 @@ EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint); */ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) { + struct kgdb_io *old_dbg_io_ops; int err; spin_lock(&kgdb_registration_lock); - if (dbg_io_ops) { - spin_unlock(&kgdb_registration_lock); + old_dbg_io_ops = dbg_io_ops; + if (old_dbg_io_ops) { + if (!old_dbg_io_ops->deinit) { + spin_unlock(&kgdb_registration_lock); - pr_err("Another I/O driver is already registered with KGDB\n"); - return -EBUSY; + pr_err("KGDB I/O driver %s can't replace %s.\n", + new_dbg_io_ops->name, old_dbg_io_ops->name); + return -EBUSY; + } + pr_info("Replacing I/O driver %s with %s\n", + old_dbg_io_ops->name, new_dbg_io_ops->name); + old_dbg_io_ops->deinit(); } if (new_dbg_io_ops->init) { @@ -1096,6 +1104,9 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) spin_unlock(&kgdb_registration_lock); + if (old_dbg_io_ops) + return 0; + pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name); /* Arm KGDB now. */ @@ -1132,6 +1143,9 @@ void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) spin_unlock(&kgdb_registration_lock); + if (old_dbg_io_ops->deinit) + old_dbg_io_ops->deinit(); + pr_info("Unregistered I/O driver %s, debugger disabled\n", old_dbg_io_ops->name); } |