1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Based on the same principle as kgdboe using the NETPOLL api, this 4 * driver uses a console polling api to implement a gdb serial inteface 5 * which is multiplexed on a console port. 6 * 7 * Maintainer: Jason Wessel <jason.wessel@windriver.com> 8 * 9 * 2007-2008 (c) Jason Wessel - Wind River Systems, Inc. 10 */ 11 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13 14 #include <linux/kernel.h> 15 #include <linux/ctype.h> 16 #include <linux/kgdb.h> 17 #include <linux/kdb.h> 18 #include <linux/tty.h> 19 #include <linux/console.h> 20 #include <linux/vt_kern.h> 21 #include <linux/input.h> 22 #include <linux/module.h> 23 24 #define MAX_CONFIG_LEN 40 25 26 static struct kgdb_io kgdboc_io_ops; 27 28 /* -1 = init not run yet, 0 = unconfigured, 1 = configured. */ 29 static int configured = -1; 30 31 static char config[MAX_CONFIG_LEN]; 32 static struct kparam_string kps = { 33 .string = config, 34 .maxlen = MAX_CONFIG_LEN, 35 }; 36 37 static int kgdboc_use_kms; /* 1 if we use kernel mode switching */ 38 static struct tty_driver *kgdb_tty_driver; 39 static int kgdb_tty_line; 40 41 #ifdef CONFIG_KDB_KEYBOARD 42 static int kgdboc_reset_connect(struct input_handler *handler, 43 struct input_dev *dev, 44 const struct input_device_id *id) 45 { 46 input_reset_device(dev); 47 48 /* Return an error - we do not want to bind, just to reset */ 49 return -ENODEV; 50 } 51 52 static void kgdboc_reset_disconnect(struct input_handle *handle) 53 { 54 /* We do not expect anyone to actually bind to us */ 55 BUG(); 56 } 57 58 static const struct input_device_id kgdboc_reset_ids[] = { 59 { 60 .flags = INPUT_DEVICE_ID_MATCH_EVBIT, 61 .evbit = { BIT_MASK(EV_KEY) }, 62 }, 63 { } 64 }; 65 66 static struct input_handler kgdboc_reset_handler = { 67 .connect = kgdboc_reset_connect, 68 .disconnect = kgdboc_reset_disconnect, 69 .name = "kgdboc_reset", 70 .id_table = kgdboc_reset_ids, 71 }; 72 73 static DEFINE_MUTEX(kgdboc_reset_mutex); 74 75 static void kgdboc_restore_input_helper(struct work_struct *dummy) 76 { 77 /* 78 * We need to take a mutex to prevent several instances of 79 * this work running on different CPUs so they don't try 80 * to register again already registered handler. 81 */ 82 mutex_lock(&kgdboc_reset_mutex); 83 84 if (input_register_handler(&kgdboc_reset_handler) == 0) 85 input_unregister_handler(&kgdboc_reset_handler); 86 87 mutex_unlock(&kgdboc_reset_mutex); 88 } 89 90 static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper); 91 92 static void kgdboc_restore_input(void) 93 { 94 if (likely(system_state == SYSTEM_RUNNING)) 95 schedule_work(&kgdboc_restore_input_work); 96 } 97 98 static int kgdboc_register_kbd(char **cptr) 99 { 100 if (strncmp(*cptr, "kbd", 3) == 0 || 101 strncmp(*cptr, "kdb", 3) == 0) { 102 if (kdb_poll_idx < KDB_POLL_FUNC_MAX) { 103 kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char; 104 kdb_poll_idx++; 105 if (cptr[0][3] == ',') 106 *cptr += 4; 107 else 108 return 1; 109 } 110 } 111 return 0; 112 } 113 114 static void kgdboc_unregister_kbd(void) 115 { 116 int i; 117 118 for (i = 0; i < kdb_poll_idx; i++) { 119 if (kdb_poll_funcs[i] == kdb_get_kbd_char) { 120 kdb_poll_idx--; 121 kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx]; 122 kdb_poll_funcs[kdb_poll_idx] = NULL; 123 i--; 124 } 125 } 126 flush_work(&kgdboc_restore_input_work); 127 } 128 #else /* ! CONFIG_KDB_KEYBOARD */ 129 #define kgdboc_register_kbd(x) 0 130 #define kgdboc_unregister_kbd() 131 #define kgdboc_restore_input() 132 #endif /* ! CONFIG_KDB_KEYBOARD */ 133 134 static void cleanup_kgdboc(void) 135 { 136 if (kgdb_unregister_nmi_console()) 137 return; 138 kgdboc_unregister_kbd(); 139 if (configured == 1) 140 kgdb_unregister_io_module(&kgdboc_io_ops); 141 } 142 143 static int configure_kgdboc(void) 144 { 145 struct tty_driver *p; 146 int tty_line = 0; 147 int err = -ENODEV; 148 char *cptr = config; 149 struct console *cons; 150 151 if (!strlen(config) || isspace(config[0])) { 152 err = 0; 153 goto noconfig; 154 } 155 156 kgdboc_io_ops.is_console = 0; 157 kgdb_tty_driver = NULL; 158 159 kgdboc_use_kms = 0; 160 if (strncmp(cptr, "kms,", 4) == 0) { 161 cptr += 4; 162 kgdboc_use_kms = 1; 163 } 164 165 if (kgdboc_register_kbd(&cptr)) 166 goto do_register; 167 168 p = tty_find_polling_driver(cptr, &tty_line); 169 if (!p) 170 goto noconfig; 171 172 cons = console_drivers; 173 while (cons) { 174 int idx; 175 if (cons->device && cons->device(cons, &idx) == p && 176 idx == tty_line) { 177 kgdboc_io_ops.is_console = 1; 178 break; 179 } 180 cons = cons->next; 181 } 182 183 kgdb_tty_driver = p; 184 kgdb_tty_line = tty_line; 185 186 do_register: 187 err = kgdb_register_io_module(&kgdboc_io_ops); 188 if (err) 189 goto noconfig; 190 191 err = kgdb_register_nmi_console(); 192 if (err) 193 goto nmi_con_failed; 194 195 configured = 1; 196 197 return 0; 198 199 nmi_con_failed: 200 kgdb_unregister_io_module(&kgdboc_io_ops); 201 noconfig: 202 kgdboc_unregister_kbd(); 203 config[0] = 0; 204 configured = 0; 205 cleanup_kgdboc(); 206 207 return err; 208 } 209 210 static int __init init_kgdboc(void) 211 { 212 /* Already configured? */ 213 if (configured == 1) 214 return 0; 215 216 return configure_kgdboc(); 217 } 218 219 static int kgdboc_get_char(void) 220 { 221 if (!kgdb_tty_driver) 222 return -1; 223 return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver, 224 kgdb_tty_line); 225 } 226 227 static void kgdboc_put_char(u8 chr) 228 { 229 if (!kgdb_tty_driver) 230 return; 231 kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver, 232 kgdb_tty_line, chr); 233 } 234 235 static int param_set_kgdboc_var(const char *kmessage, 236 const struct kernel_param *kp) 237 { 238 size_t len = strlen(kmessage); 239 240 if (len >= MAX_CONFIG_LEN) { 241 pr_err("config string too long\n"); 242 return -ENOSPC; 243 } 244 245 /* Only copy in the string if the init function has not run yet */ 246 if (configured < 0) { 247 strcpy(config, kmessage); 248 return 0; 249 } 250 251 if (kgdb_connected) { 252 pr_err("Cannot reconfigure while KGDB is connected.\n"); 253 254 return -EBUSY; 255 } 256 257 strcpy(config, kmessage); 258 /* Chop out \n char as a result of echo */ 259 if (len && config[len - 1] == '\n') 260 config[len - 1] = '\0'; 261 262 if (configured == 1) 263 cleanup_kgdboc(); 264 265 /* Go and configure with the new params. */ 266 return configure_kgdboc(); 267 } 268 269 static int dbg_restore_graphics; 270 271 static void kgdboc_pre_exp_handler(void) 272 { 273 if (!dbg_restore_graphics && kgdboc_use_kms) { 274 dbg_restore_graphics = 1; 275 con_debug_enter(vc_cons[fg_console].d); 276 } 277 /* Increment the module count when the debugger is active */ 278 if (!kgdb_connected) 279 try_module_get(THIS_MODULE); 280 281 atomic_inc(&ignore_console_lock_warning); 282 } 283 284 static void kgdboc_post_exp_handler(void) 285 { 286 atomic_dec(&ignore_console_lock_warning); 287 288 /* decrement the module count when the debugger detaches */ 289 if (!kgdb_connected) 290 module_put(THIS_MODULE); 291 if (kgdboc_use_kms && dbg_restore_graphics) { 292 dbg_restore_graphics = 0; 293 con_debug_leave(); 294 } 295 kgdboc_restore_input(); 296 } 297 298 static struct kgdb_io kgdboc_io_ops = { 299 .name = "kgdboc", 300 .read_char = kgdboc_get_char, 301 .write_char = kgdboc_put_char, 302 .pre_exception = kgdboc_pre_exp_handler, 303 .post_exception = kgdboc_post_exp_handler, 304 }; 305 306 #ifdef CONFIG_KGDB_SERIAL_CONSOLE 307 static int kgdboc_option_setup(char *opt) 308 { 309 if (!opt) { 310 pr_err("config string not provided\n"); 311 return -EINVAL; 312 } 313 314 if (strlen(opt) >= MAX_CONFIG_LEN) { 315 pr_err("config string too long\n"); 316 return -ENOSPC; 317 } 318 strcpy(config, opt); 319 320 return 0; 321 } 322 323 __setup("kgdboc=", kgdboc_option_setup); 324 325 326 /* This is only available if kgdboc is a built in for early debugging */ 327 static int __init kgdboc_early_init(char *opt) 328 { 329 /* save the first character of the config string because the 330 * init routine can destroy it. 331 */ 332 char save_ch; 333 334 kgdboc_option_setup(opt); 335 save_ch = config[0]; 336 init_kgdboc(); 337 config[0] = save_ch; 338 return 0; 339 } 340 341 early_param("ekgdboc", kgdboc_early_init); 342 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */ 343 344 module_init(init_kgdboc); 345 module_exit(cleanup_kgdboc); 346 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644); 347 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]"); 348 MODULE_DESCRIPTION("KGDB Console TTY Driver"); 349 MODULE_LICENSE("GPL"); 350