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 goto noconfig; 153 154 kgdboc_io_ops.is_console = 0; 155 kgdb_tty_driver = NULL; 156 157 kgdboc_use_kms = 0; 158 if (strncmp(cptr, "kms,", 4) == 0) { 159 cptr += 4; 160 kgdboc_use_kms = 1; 161 } 162 163 if (kgdboc_register_kbd(&cptr)) 164 goto do_register; 165 166 p = tty_find_polling_driver(cptr, &tty_line); 167 if (!p) 168 goto noconfig; 169 170 cons = console_drivers; 171 while (cons) { 172 int idx; 173 if (cons->device && cons->device(cons, &idx) == p && 174 idx == tty_line) { 175 kgdboc_io_ops.is_console = 1; 176 break; 177 } 178 cons = cons->next; 179 } 180 181 kgdb_tty_driver = p; 182 kgdb_tty_line = tty_line; 183 184 do_register: 185 err = kgdb_register_io_module(&kgdboc_io_ops); 186 if (err) 187 goto noconfig; 188 189 err = kgdb_register_nmi_console(); 190 if (err) 191 goto nmi_con_failed; 192 193 configured = 1; 194 195 return 0; 196 197 nmi_con_failed: 198 kgdb_unregister_io_module(&kgdboc_io_ops); 199 noconfig: 200 kgdboc_unregister_kbd(); 201 config[0] = 0; 202 configured = 0; 203 cleanup_kgdboc(); 204 205 return err; 206 } 207 208 static int __init init_kgdboc(void) 209 { 210 /* Already configured? */ 211 if (configured == 1) 212 return 0; 213 214 return configure_kgdboc(); 215 } 216 217 static int kgdboc_get_char(void) 218 { 219 if (!kgdb_tty_driver) 220 return -1; 221 return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver, 222 kgdb_tty_line); 223 } 224 225 static void kgdboc_put_char(u8 chr) 226 { 227 if (!kgdb_tty_driver) 228 return; 229 kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver, 230 kgdb_tty_line, chr); 231 } 232 233 static int param_set_kgdboc_var(const char *kmessage, 234 const struct kernel_param *kp) 235 { 236 int len = strlen(kmessage); 237 238 if (len >= MAX_CONFIG_LEN) { 239 pr_err("config string too long\n"); 240 return -ENOSPC; 241 } 242 243 /* Only copy in the string if the init function has not run yet */ 244 if (configured < 0) { 245 strcpy(config, kmessage); 246 return 0; 247 } 248 249 if (kgdb_connected) { 250 pr_err("Cannot reconfigure while KGDB is connected.\n"); 251 252 return -EBUSY; 253 } 254 255 strcpy(config, kmessage); 256 /* Chop out \n char as a result of echo */ 257 if (config[len - 1] == '\n') 258 config[len - 1] = '\0'; 259 260 if (configured == 1) 261 cleanup_kgdboc(); 262 263 /* Go and configure with the new params. */ 264 return configure_kgdboc(); 265 } 266 267 static int dbg_restore_graphics; 268 269 static void kgdboc_pre_exp_handler(void) 270 { 271 if (!dbg_restore_graphics && kgdboc_use_kms) { 272 dbg_restore_graphics = 1; 273 con_debug_enter(vc_cons[fg_console].d); 274 } 275 /* Increment the module count when the debugger is active */ 276 if (!kgdb_connected) 277 try_module_get(THIS_MODULE); 278 } 279 280 static void kgdboc_post_exp_handler(void) 281 { 282 /* decrement the module count when the debugger detaches */ 283 if (!kgdb_connected) 284 module_put(THIS_MODULE); 285 if (kgdboc_use_kms && dbg_restore_graphics) { 286 dbg_restore_graphics = 0; 287 con_debug_leave(); 288 } 289 kgdboc_restore_input(); 290 } 291 292 static struct kgdb_io kgdboc_io_ops = { 293 .name = "kgdboc", 294 .read_char = kgdboc_get_char, 295 .write_char = kgdboc_put_char, 296 .pre_exception = kgdboc_pre_exp_handler, 297 .post_exception = kgdboc_post_exp_handler, 298 }; 299 300 #ifdef CONFIG_KGDB_SERIAL_CONSOLE 301 static int kgdboc_option_setup(char *opt) 302 { 303 if (!opt) { 304 pr_err("config string not provided\n"); 305 return -EINVAL; 306 } 307 308 if (strlen(opt) >= MAX_CONFIG_LEN) { 309 pr_err("config string too long\n"); 310 return -ENOSPC; 311 } 312 strcpy(config, opt); 313 314 return 0; 315 } 316 317 __setup("kgdboc=", kgdboc_option_setup); 318 319 320 /* This is only available if kgdboc is a built in for early debugging */ 321 static int __init kgdboc_early_init(char *opt) 322 { 323 /* save the first character of the config string because the 324 * init routine can destroy it. 325 */ 326 char save_ch; 327 328 kgdboc_option_setup(opt); 329 save_ch = config[0]; 330 init_kgdboc(); 331 config[0] = save_ch; 332 return 0; 333 } 334 335 early_param("ekgdboc", kgdboc_early_init); 336 #endif /* CONFIG_KGDB_SERIAL_CONSOLE */ 337 338 module_init(init_kgdboc); 339 module_exit(cleanup_kgdboc); 340 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644); 341 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]"); 342 MODULE_DESCRIPTION("KGDB Console TTY Driver"); 343 MODULE_LICENSE("GPL"); 344