xref: /linux/init/main.c (revision 6a4aee277740d04ac0fd54cfa17cc28261932ddc)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/init/main.c
4  *
5  *  Copyright (C) 1991, 1992  Linus Torvalds
6  *
7  *  GK 2/5/95  -  Changed to support mounting root fs via NFS
8  *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
9  *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
10  *  Simplified starting of init:  Michael A. Griffith <grif@acm.org>
11  */
12 
13 #define DEBUG		/* Enable initcall_debug */
14 
15 #include <linux/types.h>
16 #include <linux/extable.h>
17 #include <linux/module.h>
18 #include <linux/proc_fs.h>
19 #include <linux/binfmts.h>
20 #include <linux/kernel.h>
21 #include <linux/syscalls.h>
22 #include <linux/stackprotector.h>
23 #include <linux/string.h>
24 #include <linux/ctype.h>
25 #include <linux/delay.h>
26 #include <linux/ioport.h>
27 #include <linux/init.h>
28 #include <linux/initrd.h>
29 #include <linux/memblock.h>
30 #include <linux/acpi.h>
31 #include <linux/bootconfig.h>
32 #include <linux/console.h>
33 #include <linux/nmi.h>
34 #include <linux/percpu.h>
35 #include <linux/kmod.h>
36 #include <linux/kprobes.h>
37 #include <linux/kmsan.h>
38 #include <linux/vmalloc.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/start_kernel.h>
41 #include <linux/security.h>
42 #include <linux/smp.h>
43 #include <linux/profile.h>
44 #include <linux/kfence.h>
45 #include <linux/rcupdate.h>
46 #include <linux/srcu.h>
47 #include <linux/moduleparam.h>
48 #include <linux/kallsyms.h>
49 #include <linux/buildid.h>
50 #include <linux/writeback.h>
51 #include <linux/cpu.h>
52 #include <linux/cpuset.h>
53 #include <linux/cgroup.h>
54 #include <linux/efi.h>
55 #include <linux/tick.h>
56 #include <linux/sched/isolation.h>
57 #include <linux/interrupt.h>
58 #include <linux/taskstats_kern.h>
59 #include <linux/delayacct.h>
60 #include <linux/unistd.h>
61 #include <linux/utsname.h>
62 #include <linux/rmap.h>
63 #include <linux/mempolicy.h>
64 #include <linux/key.h>
65 #include <linux/debug_locks.h>
66 #include <linux/debugobjects.h>
67 #include <linux/lockdep.h>
68 #include <linux/kmemleak.h>
69 #include <linux/padata.h>
70 #include <linux/pid_namespace.h>
71 #include <linux/device/driver.h>
72 #include <linux/kthread.h>
73 #include <linux/sched.h>
74 #include <linux/sched/init.h>
75 #include <linux/signal.h>
76 #include <linux/idr.h>
77 #include <linux/kgdb.h>
78 #include <linux/ftrace.h>
79 #include <linux/async.h>
80 #include <linux/shmem_fs.h>
81 #include <linux/slab.h>
82 #include <linux/perf_event.h>
83 #include <linux/ptrace.h>
84 #include <linux/pti.h>
85 #include <linux/blkdev.h>
86 #include <linux/sched/clock.h>
87 #include <linux/sched/task.h>
88 #include <linux/sched/task_stack.h>
89 #include <linux/context_tracking.h>
90 #include <linux/random.h>
91 #include <linux/moduleloader.h>
92 #include <linux/list.h>
93 #include <linux/integrity.h>
94 #include <linux/proc_ns.h>
95 #include <linux/io.h>
96 #include <linux/cache.h>
97 #include <linux/rodata_test.h>
98 #include <linux/jump_label.h>
99 #include <linux/kcsan.h>
100 #include <linux/init_syscalls.h>
101 #include <linux/stackdepot.h>
102 #include <linux/randomize_kstack.h>
103 #include <linux/pidfs.h>
104 #include <linux/ptdump.h>
105 #include <net/net_namespace.h>
106 
107 #include <asm/io.h>
108 #include <asm/setup.h>
109 #include <asm/sections.h>
110 #include <asm/cacheflush.h>
111 
112 #define CREATE_TRACE_POINTS
113 #include <trace/events/initcall.h>
114 
115 #include <kunit/test.h>
116 
117 static int kernel_init(void *);
118 
119 /*
120  * Debug helper: via this flag we know that we are in 'early bootup code'
121  * where only the boot processor is running with IRQ disabled.  This means
122  * two things - IRQ must not be enabled before the flag is cleared and some
123  * operations which are not allowed with IRQ disabled are allowed while the
124  * flag is set.
125  */
126 bool early_boot_irqs_disabled __read_mostly;
127 
128 enum system_states system_state __read_mostly;
129 EXPORT_SYMBOL(system_state);
130 
131 /*
132  * Boot command-line arguments
133  */
134 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
135 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
136 
137 /* Default late time init is NULL. archs can override this later. */
138 void (*__initdata late_time_init)(void);
139 
140 /* Untouched command line saved by arch-specific code. */
141 char __initdata boot_command_line[COMMAND_LINE_SIZE];
142 /* Untouched saved command line (eg. for /proc) */
143 char *saved_command_line __ro_after_init;
144 unsigned int saved_command_line_len __ro_after_init;
145 /* Command line for parameter parsing */
146 static char *static_command_line;
147 /* Untouched extra command line */
148 static char *extra_command_line;
149 /* Extra init arguments */
150 static char *extra_init_args;
151 
152 #ifdef CONFIG_BOOT_CONFIG
153 /* Is bootconfig on command line? */
154 static bool bootconfig_found;
155 static size_t initargs_offs;
156 #else
157 # define bootconfig_found false
158 # define initargs_offs 0
159 #endif
160 
161 static char *execute_command;
162 static char *ramdisk_execute_command = "/init";
163 
164 /*
165  * Used to generate warnings if static_key manipulation functions are used
166  * before jump_label_init is called.
167  */
168 bool static_key_initialized __read_mostly;
169 EXPORT_SYMBOL_GPL(static_key_initialized);
170 
171 /*
172  * If set, this is an indication to the drivers that reset the underlying
173  * device before going ahead with the initialization otherwise driver might
174  * rely on the BIOS and skip the reset operation.
175  *
176  * This is useful if kernel is booting in an unreliable environment.
177  * For ex. kdump situation where previous kernel has crashed, BIOS has been
178  * skipped and devices will be in unknown state.
179  */
180 unsigned int reset_devices;
181 EXPORT_SYMBOL(reset_devices);
182 
183 static int __init set_reset_devices(char *str)
184 {
185 	reset_devices = 1;
186 	return 1;
187 }
188 
189 __setup("reset_devices", set_reset_devices);
190 
191 static const char *argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
192 const char *envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
193 static const char *panic_later, *panic_param;
194 
195 static bool __init obsolete_checksetup(char *line)
196 {
197 	const struct obs_kernel_param *p;
198 	bool had_early_param = false;
199 
200 	p = __setup_start;
201 	do {
202 		int n = strlen(p->str);
203 		if (parameqn(line, p->str, n)) {
204 			if (p->early) {
205 				/* Already done in parse_early_param?
206 				 * (Needs exact match on param part).
207 				 * Keep iterating, as we can have early
208 				 * params and __setups of same names 8( */
209 				if (line[n] == '\0' || line[n] == '=')
210 					had_early_param = true;
211 			} else if (!p->setup_func) {
212 				pr_warn("Parameter %s is obsolete, ignored\n",
213 					p->str);
214 				return true;
215 			} else if (p->setup_func(line + n))
216 				return true;
217 		}
218 		p++;
219 	} while (p < __setup_end);
220 
221 	return had_early_param;
222 }
223 
224 /*
225  * This should be approx 2 Bo*oMips to start (note initial shift), and will
226  * still work even if initially too large, it will just take slightly longer
227  */
228 unsigned long loops_per_jiffy = (1<<12);
229 EXPORT_SYMBOL(loops_per_jiffy);
230 
231 static int __init debug_kernel(char *str)
232 {
233 	console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
234 	return 0;
235 }
236 
237 static int __init quiet_kernel(char *str)
238 {
239 	console_loglevel = CONSOLE_LOGLEVEL_QUIET;
240 	return 0;
241 }
242 
243 early_param("debug", debug_kernel);
244 early_param("quiet", quiet_kernel);
245 
246 static int __init loglevel(char *str)
247 {
248 	int newlevel;
249 
250 	/*
251 	 * Only update loglevel value when a correct setting was passed,
252 	 * to prevent blind crashes (when loglevel being set to 0) that
253 	 * are quite hard to debug
254 	 */
255 	if (get_option(&str, &newlevel)) {
256 		console_loglevel = newlevel;
257 		return 0;
258 	}
259 
260 	return -EINVAL;
261 }
262 
263 early_param("loglevel", loglevel);
264 
265 #ifdef CONFIG_BLK_DEV_INITRD
266 static void * __init get_boot_config_from_initrd(size_t *_size)
267 {
268 	u32 size, csum;
269 	char *data;
270 	u32 *hdr;
271 	int i;
272 
273 	if (!initrd_end)
274 		return NULL;
275 
276 	data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;
277 	/*
278 	 * Since Grub may align the size of initrd to 4, we must
279 	 * check the preceding 3 bytes as well.
280 	 */
281 	for (i = 0; i < 4; i++) {
282 		if (!memcmp(data, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN))
283 			goto found;
284 		data--;
285 	}
286 	return NULL;
287 
288 found:
289 	hdr = (u32 *)(data - 8);
290 	size = le32_to_cpu(hdr[0]);
291 	csum = le32_to_cpu(hdr[1]);
292 
293 	data = ((void *)hdr) - size;
294 	if ((unsigned long)data < initrd_start) {
295 		pr_err("bootconfig size %d is greater than initrd size %ld\n",
296 			size, initrd_end - initrd_start);
297 		return NULL;
298 	}
299 
300 	if (xbc_calc_checksum(data, size) != csum) {
301 		pr_err("bootconfig checksum failed\n");
302 		return NULL;
303 	}
304 
305 	/* Remove bootconfig from initramfs/initrd */
306 	initrd_end = (unsigned long)data;
307 	if (_size)
308 		*_size = size;
309 
310 	return data;
311 }
312 #else
313 static void * __init get_boot_config_from_initrd(size_t *_size)
314 {
315 	return NULL;
316 }
317 #endif
318 
319 #ifdef CONFIG_BOOT_CONFIG
320 
321 static char xbc_namebuf[XBC_KEYLEN_MAX] __initdata;
322 
323 #define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
324 
325 static int __init xbc_snprint_cmdline(char *buf, size_t size,
326 				      struct xbc_node *root)
327 {
328 	struct xbc_node *knode, *vnode;
329 	char *end = buf + size;
330 	const char *val;
331 	int ret;
332 
333 	xbc_node_for_each_key_value(root, knode, val) {
334 		ret = xbc_node_compose_key_after(root, knode,
335 					xbc_namebuf, XBC_KEYLEN_MAX);
336 		if (ret < 0)
337 			return ret;
338 
339 		vnode = xbc_node_get_child(knode);
340 		if (!vnode) {
341 			ret = snprintf(buf, rest(buf, end), "%s ", xbc_namebuf);
342 			if (ret < 0)
343 				return ret;
344 			buf += ret;
345 			continue;
346 		}
347 		xbc_array_for_each_value(vnode, val) {
348 			ret = snprintf(buf, rest(buf, end), "%s=\"%s\" ",
349 				       xbc_namebuf, val);
350 			if (ret < 0)
351 				return ret;
352 			buf += ret;
353 		}
354 	}
355 
356 	return buf - (end - size);
357 }
358 #undef rest
359 
360 /* Make an extra command line under given key word */
361 static char * __init xbc_make_cmdline(const char *key)
362 {
363 	struct xbc_node *root;
364 	char *new_cmdline;
365 	int ret, len = 0;
366 
367 	root = xbc_find_node(key);
368 	if (!root)
369 		return NULL;
370 
371 	/* Count required buffer size */
372 	len = xbc_snprint_cmdline(NULL, 0, root);
373 	if (len <= 0)
374 		return NULL;
375 
376 	new_cmdline = memblock_alloc(len + 1, SMP_CACHE_BYTES);
377 	if (!new_cmdline) {
378 		pr_err("Failed to allocate memory for extra kernel cmdline.\n");
379 		return NULL;
380 	}
381 
382 	ret = xbc_snprint_cmdline(new_cmdline, len + 1, root);
383 	if (ret < 0 || ret > len) {
384 		pr_err("Failed to print extra kernel cmdline.\n");
385 		memblock_free(new_cmdline, len + 1);
386 		return NULL;
387 	}
388 
389 	return new_cmdline;
390 }
391 
392 static int __init bootconfig_params(char *param, char *val,
393 				    const char *unused, void *arg)
394 {
395 	if (strcmp(param, "bootconfig") == 0) {
396 		bootconfig_found = true;
397 	}
398 	return 0;
399 }
400 
401 static int __init warn_bootconfig(char *str)
402 {
403 	/* The 'bootconfig' has been handled by bootconfig_params(). */
404 	return 0;
405 }
406 
407 static void __init setup_boot_config(void)
408 {
409 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
410 	const char *msg, *data;
411 	int pos, ret;
412 	size_t size;
413 	char *err;
414 
415 	/* Cut out the bootconfig data even if we have no bootconfig option */
416 	data = get_boot_config_from_initrd(&size);
417 	/* If there is no bootconfig in initrd, try embedded one. */
418 	if (!data)
419 		data = xbc_get_embedded_bootconfig(&size);
420 
421 	strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
422 	err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
423 			 bootconfig_params);
424 
425 	if (IS_ERR(err) || !(bootconfig_found || IS_ENABLED(CONFIG_BOOT_CONFIG_FORCE)))
426 		return;
427 
428 	/* parse_args() stops at the next param of '--' and returns an address */
429 	if (err)
430 		initargs_offs = err - tmp_cmdline;
431 
432 	if (!data) {
433 		/* If user intended to use bootconfig, show an error level message */
434 		if (bootconfig_found)
435 			pr_err("'bootconfig' found on command line, but no bootconfig found\n");
436 		else
437 			pr_info("No bootconfig data provided, so skipping bootconfig");
438 		return;
439 	}
440 
441 	if (size >= XBC_DATA_MAX) {
442 		pr_err("bootconfig size %ld greater than max size %d\n",
443 			(long)size, XBC_DATA_MAX);
444 		return;
445 	}
446 
447 	ret = xbc_init(data, size, &msg, &pos);
448 	if (ret < 0) {
449 		if (pos < 0)
450 			pr_err("Failed to init bootconfig: %s.\n", msg);
451 		else
452 			pr_err("Failed to parse bootconfig: %s at %d.\n",
453 				msg, pos);
454 	} else {
455 		xbc_get_info(&ret, NULL);
456 		pr_info("Load bootconfig: %ld bytes %d nodes\n", (long)size, ret);
457 		/* keys starting with "kernel." are passed via cmdline */
458 		extra_command_line = xbc_make_cmdline("kernel");
459 		/* Also, "init." keys are init arguments */
460 		extra_init_args = xbc_make_cmdline("init");
461 	}
462 	return;
463 }
464 
465 static void __init exit_boot_config(void)
466 {
467 	xbc_exit();
468 }
469 
470 #else	/* !CONFIG_BOOT_CONFIG */
471 
472 static void __init setup_boot_config(void)
473 {
474 	/* Remove bootconfig data from initrd */
475 	get_boot_config_from_initrd(NULL);
476 }
477 
478 static int __init warn_bootconfig(char *str)
479 {
480 	pr_warn("WARNING: 'bootconfig' found on the kernel command line but CONFIG_BOOT_CONFIG is not set.\n");
481 	return 0;
482 }
483 
484 #define exit_boot_config()	do {} while (0)
485 
486 #endif	/* CONFIG_BOOT_CONFIG */
487 
488 early_param("bootconfig", warn_bootconfig);
489 
490 /* Change NUL term back to "=", to make "param" the whole string. */
491 static void __init repair_env_string(char *param, char *val)
492 {
493 	if (val) {
494 		/* param=val or param="val"? */
495 		if (val == param+strlen(param)+1)
496 			val[-1] = '=';
497 		else if (val == param+strlen(param)+2) {
498 			val[-2] = '=';
499 			memmove(val-1, val, strlen(val)+1);
500 		} else
501 			BUG();
502 	}
503 }
504 
505 /* Anything after -- gets handed straight to init. */
506 static int __init set_init_arg(char *param, char *val,
507 			       const char *unused, void *arg)
508 {
509 	unsigned int i;
510 
511 	if (panic_later)
512 		return 0;
513 
514 	repair_env_string(param, val);
515 
516 	for (i = 0; argv_init[i]; i++) {
517 		if (i == MAX_INIT_ARGS) {
518 			panic_later = "init";
519 			panic_param = param;
520 			return 0;
521 		}
522 	}
523 	argv_init[i] = param;
524 	return 0;
525 }
526 
527 /*
528  * Unknown boot options get handed to init, unless they look like
529  * unused parameters (modprobe will find them in /proc/cmdline).
530  */
531 static int __init unknown_bootoption(char *param, char *val,
532 				     const char *unused, void *arg)
533 {
534 	size_t len = strlen(param);
535 
536 	/* Handle params aliased to sysctls */
537 	if (sysctl_is_alias(param))
538 		return 0;
539 
540 	repair_env_string(param, val);
541 
542 	/* Handle obsolete-style parameters */
543 	if (obsolete_checksetup(param))
544 		return 0;
545 
546 	/* Unused module parameter. */
547 	if (strnchr(param, len, '.'))
548 		return 0;
549 
550 	if (panic_later)
551 		return 0;
552 
553 	if (val) {
554 		/* Environment option */
555 		unsigned int i;
556 		for (i = 0; envp_init[i]; i++) {
557 			if (i == MAX_INIT_ENVS) {
558 				panic_later = "env";
559 				panic_param = param;
560 			}
561 			if (!strncmp(param, envp_init[i], len+1))
562 				break;
563 		}
564 		envp_init[i] = param;
565 	} else {
566 		/* Command line option */
567 		unsigned int i;
568 		for (i = 0; argv_init[i]; i++) {
569 			if (i == MAX_INIT_ARGS) {
570 				panic_later = "init";
571 				panic_param = param;
572 			}
573 		}
574 		argv_init[i] = param;
575 	}
576 	return 0;
577 }
578 
579 static int __init init_setup(char *str)
580 {
581 	unsigned int i;
582 
583 	execute_command = str;
584 	/*
585 	 * In case LILO is going to boot us with default command line,
586 	 * it prepends "auto" before the whole cmdline which makes
587 	 * the shell think it should execute a script with such name.
588 	 * So we ignore all arguments entered _before_ init=... [MJ]
589 	 */
590 	for (i = 1; i < MAX_INIT_ARGS; i++)
591 		argv_init[i] = NULL;
592 	return 1;
593 }
594 __setup("init=", init_setup);
595 
596 static int __init rdinit_setup(char *str)
597 {
598 	unsigned int i;
599 
600 	ramdisk_execute_command = str;
601 	/* See "auto" comment in init_setup */
602 	for (i = 1; i < MAX_INIT_ARGS; i++)
603 		argv_init[i] = NULL;
604 	return 1;
605 }
606 __setup("rdinit=", rdinit_setup);
607 
608 #ifndef CONFIG_SMP
609 static inline void setup_nr_cpu_ids(void) { }
610 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
611 #endif
612 
613 /*
614  * We need to store the untouched command line for future reference.
615  * We also need to store the touched command line since the parameter
616  * parsing is performed in place, and we should allow a component to
617  * store reference of name/value for future reference.
618  */
619 static void __init setup_command_line(char *command_line)
620 {
621 	size_t len, xlen = 0, ilen = 0;
622 
623 	if (extra_command_line)
624 		xlen = strlen(extra_command_line);
625 	if (extra_init_args)
626 		ilen = strlen(extra_init_args) + 4; /* for " -- " */
627 
628 	len = xlen + strlen(boot_command_line) + 1;
629 
630 	saved_command_line = memblock_alloc(len + ilen, SMP_CACHE_BYTES);
631 	if (!saved_command_line)
632 		panic("%s: Failed to allocate %zu bytes\n", __func__, len + ilen);
633 
634 	static_command_line = memblock_alloc(len, SMP_CACHE_BYTES);
635 	if (!static_command_line)
636 		panic("%s: Failed to allocate %zu bytes\n", __func__, len);
637 
638 	if (xlen) {
639 		/*
640 		 * We have to put extra_command_line before boot command
641 		 * lines because there could be dashes (separator of init
642 		 * command line) in the command lines.
643 		 */
644 		strcpy(saved_command_line, extra_command_line);
645 		strcpy(static_command_line, extra_command_line);
646 	}
647 	strcpy(saved_command_line + xlen, boot_command_line);
648 	strcpy(static_command_line + xlen, command_line);
649 
650 	if (ilen) {
651 		/*
652 		 * Append supplemental init boot args to saved_command_line
653 		 * so that user can check what command line options passed
654 		 * to init.
655 		 * The order should always be
656 		 * " -- "[bootconfig init-param][cmdline init-param]
657 		 */
658 		if (initargs_offs) {
659 			len = xlen + initargs_offs;
660 			strcpy(saved_command_line + len, extra_init_args);
661 			len += ilen - 4;	/* strlen(extra_init_args) */
662 			strcpy(saved_command_line + len,
663 				boot_command_line + initargs_offs - 1);
664 		} else {
665 			len = strlen(saved_command_line);
666 			strcpy(saved_command_line + len, " -- ");
667 			len += 4;
668 			strcpy(saved_command_line + len, extra_init_args);
669 		}
670 	}
671 
672 	saved_command_line_len = strlen(saved_command_line);
673 }
674 
675 /*
676  * We need to finalize in a non-__init function or else race conditions
677  * between the root thread and the init thread may cause start_kernel to
678  * be reaped by free_initmem before the root thread has proceeded to
679  * cpu_idle.
680  *
681  * gcc-3.4 accidentally inlines this function, so use noinline.
682  */
683 
684 static __initdata DECLARE_COMPLETION(kthreadd_done);
685 
686 static noinline void __ref __noreturn rest_init(void)
687 {
688 	struct task_struct *tsk;
689 	int pid;
690 
691 	rcu_scheduler_starting();
692 	/*
693 	 * We need to spawn init first so that it obtains pid 1, however
694 	 * the init task will end up wanting to create kthreads, which, if
695 	 * we schedule it before we create kthreadd, will OOPS.
696 	 */
697 	pid = user_mode_thread(kernel_init, NULL, CLONE_FS);
698 	/*
699 	 * Pin init on the boot CPU. Task migration is not properly working
700 	 * until sched_init_smp() has been run. It will set the allowed
701 	 * CPUs for init to the non isolated CPUs.
702 	 */
703 	rcu_read_lock();
704 	tsk = find_task_by_pid_ns(pid, &init_pid_ns);
705 	tsk->flags |= PF_NO_SETAFFINITY;
706 	set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id()));
707 	rcu_read_unlock();
708 
709 	numa_default_policy();
710 	pid = kernel_thread(kthreadd, NULL, NULL, CLONE_FS | CLONE_FILES);
711 	rcu_read_lock();
712 	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
713 	rcu_read_unlock();
714 
715 	/*
716 	 * Enable might_sleep() and smp_processor_id() checks.
717 	 * They cannot be enabled earlier because with CONFIG_PREEMPTION=y
718 	 * kernel_thread() would trigger might_sleep() splats. With
719 	 * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled
720 	 * already, but it's stuck on the kthreadd_done completion.
721 	 */
722 	system_state = SYSTEM_SCHEDULING;
723 
724 	complete(&kthreadd_done);
725 
726 	/*
727 	 * The boot idle thread must execute schedule()
728 	 * at least once to get things moving:
729 	 */
730 	schedule_preempt_disabled();
731 	/* Call into cpu_idle with preempt disabled */
732 	cpu_startup_entry(CPUHP_ONLINE);
733 }
734 
735 /* Check for early params. */
736 static int __init do_early_param(char *param, char *val,
737 				 const char *unused, void *arg)
738 {
739 	const struct obs_kernel_param *p;
740 
741 	for (p = __setup_start; p < __setup_end; p++) {
742 		if ((p->early && parameq(param, p->str)) ||
743 		    (strcmp(param, "console") == 0 &&
744 		     strcmp(p->str, "earlycon") == 0)
745 		) {
746 			if (p->setup_func(val) != 0)
747 				pr_warn("Malformed early option '%s'\n", param);
748 		}
749 	}
750 	/* We accept everything at this stage. */
751 	return 0;
752 }
753 
754 void __init parse_early_options(char *cmdline)
755 {
756 	parse_args("early options", cmdline, NULL, 0, 0, 0, NULL,
757 		   do_early_param);
758 }
759 
760 /* Arch code calls this early on, or if not, just before other parsing. */
761 void __init parse_early_param(void)
762 {
763 	static int done __initdata;
764 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
765 
766 	if (done)
767 		return;
768 
769 	/* All fall through to do_early_param. */
770 	strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
771 	parse_early_options(tmp_cmdline);
772 	done = 1;
773 }
774 
775 void __init __weak arch_post_acpi_subsys_init(void) { }
776 
777 void __init __weak smp_setup_processor_id(void)
778 {
779 }
780 
781 void __init __weak smp_prepare_boot_cpu(void)
782 {
783 }
784 
785 # if THREAD_SIZE >= PAGE_SIZE
786 void __init __weak thread_stack_cache_init(void)
787 {
788 }
789 #endif
790 
791 void __init __weak poking_init(void) { }
792 
793 void __init __weak pgtable_cache_init(void) { }
794 
795 void __init __weak trap_init(void) { }
796 
797 bool initcall_debug;
798 core_param(initcall_debug, initcall_debug, bool, 0644);
799 
800 #ifdef TRACEPOINTS_ENABLED
801 static void __init initcall_debug_enable(void);
802 #else
803 static inline void initcall_debug_enable(void)
804 {
805 }
806 #endif
807 
808 #ifdef CONFIG_RANDOMIZE_KSTACK_OFFSET
809 DEFINE_STATIC_KEY_MAYBE_RO(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT,
810 			   randomize_kstack_offset);
811 DEFINE_PER_CPU(u32, kstack_offset);
812 
813 static int __init early_randomize_kstack_offset(char *buf)
814 {
815 	int ret;
816 	bool bool_result;
817 
818 	ret = kstrtobool(buf, &bool_result);
819 	if (ret)
820 		return ret;
821 
822 	if (bool_result)
823 		static_branch_enable(&randomize_kstack_offset);
824 	else
825 		static_branch_disable(&randomize_kstack_offset);
826 	return 0;
827 }
828 early_param("randomize_kstack_offset", early_randomize_kstack_offset);
829 #endif
830 
831 static void __init print_unknown_bootoptions(void)
832 {
833 	char *unknown_options;
834 	char *end;
835 	const char *const *p;
836 	size_t len;
837 
838 	if (panic_later || (!argv_init[1] && !envp_init[2]))
839 		return;
840 
841 	/*
842 	 * Determine how many options we have to print out, plus a space
843 	 * before each
844 	 */
845 	len = 1; /* null terminator */
846 	for (p = &argv_init[1]; *p; p++) {
847 		len++;
848 		len += strlen(*p);
849 	}
850 	for (p = &envp_init[2]; *p; p++) {
851 		len++;
852 		len += strlen(*p);
853 	}
854 
855 	unknown_options = memblock_alloc(len, SMP_CACHE_BYTES);
856 	if (!unknown_options) {
857 		pr_err("%s: Failed to allocate %zu bytes\n",
858 			__func__, len);
859 		return;
860 	}
861 	end = unknown_options;
862 
863 	for (p = &argv_init[1]; *p; p++)
864 		end += sprintf(end, " %s", *p);
865 	for (p = &envp_init[2]; *p; p++)
866 		end += sprintf(end, " %s", *p);
867 
868 	/* Start at unknown_options[1] to skip the initial space */
869 	pr_notice("Unknown kernel command line parameters \"%s\", will be passed to user space.\n",
870 		&unknown_options[1]);
871 	memblock_free(unknown_options, len);
872 }
873 
874 asmlinkage __visible __init __no_sanitize_address __noreturn __no_stack_protector
875 void start_kernel(void)
876 {
877 	char *command_line;
878 	char *after_dashes;
879 
880 	set_task_stack_end_magic(&init_task);
881 	smp_setup_processor_id();
882 	debug_objects_early_init();
883 	init_vmlinux_build_id();
884 
885 	cgroup_init_early();
886 
887 	local_irq_disable();
888 	early_boot_irqs_disabled = true;
889 
890 	/*
891 	 * Interrupts are still disabled. Do necessary setups, then
892 	 * enable them.
893 	 */
894 	boot_cpu_init();
895 	page_address_init();
896 	pr_notice("%s", linux_banner);
897 	early_security_init();
898 	setup_arch(&command_line);
899 	setup_boot_config();
900 	setup_command_line(command_line);
901 	setup_nr_cpu_ids();
902 	setup_per_cpu_areas();
903 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
904 	boot_cpu_hotplug_init();
905 
906 	pr_notice("Kernel command line: %s\n", saved_command_line);
907 	/* parameters may set static keys */
908 	jump_label_init();
909 	parse_early_param();
910 	after_dashes = parse_args("Booting kernel",
911 				  static_command_line, __start___param,
912 				  __stop___param - __start___param,
913 				  -1, -1, NULL, &unknown_bootoption);
914 	print_unknown_bootoptions();
915 	if (!IS_ERR_OR_NULL(after_dashes))
916 		parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
917 			   NULL, set_init_arg);
918 	if (extra_init_args)
919 		parse_args("Setting extra init args", extra_init_args,
920 			   NULL, 0, -1, -1, NULL, set_init_arg);
921 
922 	/* Architectural and non-timekeeping rng init, before allocator init */
923 	random_init_early(command_line);
924 
925 	/*
926 	 * These use large bootmem allocations and must precede
927 	 * initalization of page allocator
928 	 */
929 	setup_log_buf(0);
930 	vfs_caches_init_early();
931 	sort_main_extable();
932 	trap_init();
933 	mm_core_init();
934 	poking_init();
935 	ftrace_init();
936 
937 	/* trace_printk can be enabled here */
938 	early_trace_init();
939 
940 	/*
941 	 * Set up the scheduler prior starting any interrupts (such as the
942 	 * timer interrupt). Full topology setup happens at smp_init()
943 	 * time - but meanwhile we still have a functioning scheduler.
944 	 */
945 	sched_init();
946 
947 	if (WARN(!irqs_disabled(),
948 		 "Interrupts were enabled *very* early, fixing it\n"))
949 		local_irq_disable();
950 	radix_tree_init();
951 	maple_tree_init();
952 
953 	/*
954 	 * Set up housekeeping before setting up workqueues to allow the unbound
955 	 * workqueue to take non-housekeeping into account.
956 	 */
957 	housekeeping_init();
958 
959 	/*
960 	 * Allow workqueue creation and work item queueing/cancelling
961 	 * early.  Work item execution depends on kthreads and starts after
962 	 * workqueue_init().
963 	 */
964 	workqueue_init_early();
965 
966 	rcu_init();
967 
968 	/* Trace events are available after this */
969 	trace_init();
970 
971 	if (initcall_debug)
972 		initcall_debug_enable();
973 
974 	context_tracking_init();
975 	/* init some links before init_ISA_irqs() */
976 	early_irq_init();
977 	init_IRQ();
978 	tick_init();
979 	rcu_init_nohz();
980 	init_timers();
981 	srcu_init();
982 	hrtimers_init();
983 	softirq_init();
984 	timekeeping_init();
985 	time_init();
986 
987 	/* This must be after timekeeping is initialized */
988 	random_init();
989 
990 	/* These make use of the fully initialized rng */
991 	kfence_init();
992 	boot_init_stack_canary();
993 
994 	perf_event_init();
995 	profile_init();
996 	call_function_init();
997 	WARN(!irqs_disabled(), "Interrupts were enabled early\n");
998 
999 	early_boot_irqs_disabled = false;
1000 	local_irq_enable();
1001 
1002 	kmem_cache_init_late();
1003 
1004 	/*
1005 	 * HACK ALERT! This is early. We're enabling the console before
1006 	 * we've done PCI setups etc, and console_init() must be aware of
1007 	 * this. But we do want output early, in case something goes wrong.
1008 	 */
1009 	console_init();
1010 	if (panic_later)
1011 		panic("Too many boot %s vars at `%s'", panic_later,
1012 		      panic_param);
1013 
1014 	lockdep_init();
1015 
1016 	/*
1017 	 * Need to run this when irqs are enabled, because it wants
1018 	 * to self-test [hard/soft]-irqs on/off lock inversion bugs
1019 	 * too:
1020 	 */
1021 	locking_selftest();
1022 
1023 #ifdef CONFIG_BLK_DEV_INITRD
1024 	if (initrd_start && !initrd_below_start_ok &&
1025 	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
1026 		pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
1027 		    page_to_pfn(virt_to_page((void *)initrd_start)),
1028 		    min_low_pfn);
1029 		initrd_start = 0;
1030 	}
1031 #endif
1032 	setup_per_cpu_pageset();
1033 	numa_policy_init();
1034 	acpi_early_init();
1035 	if (late_time_init)
1036 		late_time_init();
1037 	sched_clock_init();
1038 	calibrate_delay();
1039 
1040 	arch_cpu_finalize_init();
1041 
1042 	pid_idr_init();
1043 	anon_vma_init();
1044 #ifdef CONFIG_X86
1045 	if (efi_enabled(EFI_RUNTIME_SERVICES))
1046 		efi_enter_virtual_mode();
1047 #endif
1048 	thread_stack_cache_init();
1049 	cred_init();
1050 	fork_init();
1051 	proc_caches_init();
1052 	uts_ns_init();
1053 	key_init();
1054 	security_init();
1055 	dbg_late_init();
1056 	net_ns_init();
1057 	vfs_caches_init();
1058 	pagecache_init();
1059 	signals_init();
1060 	seq_file_init();
1061 	proc_root_init();
1062 	nsfs_init();
1063 	pidfs_init();
1064 	cpuset_init();
1065 	cgroup_init();
1066 	taskstats_init_early();
1067 	delayacct_init();
1068 
1069 	acpi_subsystem_init();
1070 	arch_post_acpi_subsys_init();
1071 	kcsan_init();
1072 
1073 	/* Do the rest non-__init'ed, we're now alive */
1074 	rest_init();
1075 
1076 	/*
1077 	 * Avoid stack canaries in callers of boot_init_stack_canary for gcc-10
1078 	 * and older.
1079 	 */
1080 #if !__has_attribute(__no_stack_protector__)
1081 	prevent_tail_call_optimization();
1082 #endif
1083 }
1084 
1085 /* Call all constructor functions linked into the kernel. */
1086 static void __init do_ctors(void)
1087 {
1088 /*
1089  * For UML, the constructors have already been called by the
1090  * normal setup code as it's just a normal ELF binary, so we
1091  * cannot do it again - but we do need CONFIG_CONSTRUCTORS
1092  * even on UML for modules.
1093  */
1094 #if defined(CONFIG_CONSTRUCTORS) && !defined(CONFIG_UML)
1095 	ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
1096 
1097 	for (; fn < (ctor_fn_t *) __ctors_end; fn++)
1098 		(*fn)();
1099 #endif
1100 }
1101 
1102 #ifdef CONFIG_KALLSYMS
1103 struct blacklist_entry {
1104 	struct list_head next;
1105 	char *buf;
1106 };
1107 
1108 static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
1109 
1110 static int __init initcall_blacklist(char *str)
1111 {
1112 	char *str_entry;
1113 	struct blacklist_entry *entry;
1114 
1115 	/* str argument is a comma-separated list of functions */
1116 	do {
1117 		str_entry = strsep(&str, ",");
1118 		if (str_entry) {
1119 			pr_debug("blacklisting initcall %s\n", str_entry);
1120 			entry = memblock_alloc(sizeof(*entry),
1121 					       SMP_CACHE_BYTES);
1122 			if (!entry)
1123 				panic("%s: Failed to allocate %zu bytes\n",
1124 				      __func__, sizeof(*entry));
1125 			entry->buf = memblock_alloc(strlen(str_entry) + 1,
1126 						    SMP_CACHE_BYTES);
1127 			if (!entry->buf)
1128 				panic("%s: Failed to allocate %zu bytes\n",
1129 				      __func__, strlen(str_entry) + 1);
1130 			strcpy(entry->buf, str_entry);
1131 			list_add(&entry->next, &blacklisted_initcalls);
1132 		}
1133 	} while (str_entry);
1134 
1135 	return 1;
1136 }
1137 
1138 static bool __init_or_module initcall_blacklisted(initcall_t fn)
1139 {
1140 	struct blacklist_entry *entry;
1141 	char fn_name[KSYM_SYMBOL_LEN];
1142 	unsigned long addr;
1143 
1144 	if (list_empty(&blacklisted_initcalls))
1145 		return false;
1146 
1147 	addr = (unsigned long) dereference_function_descriptor(fn);
1148 	sprint_symbol_no_offset(fn_name, addr);
1149 
1150 	/*
1151 	 * fn will be "function_name [module_name]" where [module_name] is not
1152 	 * displayed for built-in init functions.  Strip off the [module_name].
1153 	 */
1154 	strreplace(fn_name, ' ', '\0');
1155 
1156 	list_for_each_entry(entry, &blacklisted_initcalls, next) {
1157 		if (!strcmp(fn_name, entry->buf)) {
1158 			pr_debug("initcall %s blacklisted\n", fn_name);
1159 			return true;
1160 		}
1161 	}
1162 
1163 	return false;
1164 }
1165 #else
1166 static int __init initcall_blacklist(char *str)
1167 {
1168 	pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
1169 	return 0;
1170 }
1171 
1172 static bool __init_or_module initcall_blacklisted(initcall_t fn)
1173 {
1174 	return false;
1175 }
1176 #endif
1177 __setup("initcall_blacklist=", initcall_blacklist);
1178 
1179 static __init_or_module void
1180 trace_initcall_start_cb(void *data, initcall_t fn)
1181 {
1182 	ktime_t *calltime = data;
1183 
1184 	printk(KERN_DEBUG "calling  %pS @ %i\n", fn, task_pid_nr(current));
1185 	*calltime = ktime_get();
1186 }
1187 
1188 static __init_or_module void
1189 trace_initcall_finish_cb(void *data, initcall_t fn, int ret)
1190 {
1191 	ktime_t rettime, *calltime = data;
1192 
1193 	rettime = ktime_get();
1194 	printk(KERN_DEBUG "initcall %pS returned %d after %lld usecs\n",
1195 		 fn, ret, (unsigned long long)ktime_us_delta(rettime, *calltime));
1196 }
1197 
1198 static ktime_t initcall_calltime;
1199 
1200 #ifdef TRACEPOINTS_ENABLED
1201 static void __init initcall_debug_enable(void)
1202 {
1203 	int ret;
1204 
1205 	ret = register_trace_initcall_start(trace_initcall_start_cb,
1206 					    &initcall_calltime);
1207 	ret |= register_trace_initcall_finish(trace_initcall_finish_cb,
1208 					      &initcall_calltime);
1209 	WARN(ret, "Failed to register initcall tracepoints\n");
1210 }
1211 # define do_trace_initcall_start	trace_initcall_start
1212 # define do_trace_initcall_finish	trace_initcall_finish
1213 #else
1214 static inline void do_trace_initcall_start(initcall_t fn)
1215 {
1216 	if (!initcall_debug)
1217 		return;
1218 	trace_initcall_start_cb(&initcall_calltime, fn);
1219 }
1220 static inline void do_trace_initcall_finish(initcall_t fn, int ret)
1221 {
1222 	if (!initcall_debug)
1223 		return;
1224 	trace_initcall_finish_cb(&initcall_calltime, fn, ret);
1225 }
1226 #endif /* !TRACEPOINTS_ENABLED */
1227 
1228 int __init_or_module do_one_initcall(initcall_t fn)
1229 {
1230 	int count = preempt_count();
1231 	char msgbuf[64];
1232 	int ret;
1233 
1234 	if (initcall_blacklisted(fn))
1235 		return -EPERM;
1236 
1237 	do_trace_initcall_start(fn);
1238 	ret = fn();
1239 	do_trace_initcall_finish(fn, ret);
1240 
1241 	msgbuf[0] = 0;
1242 
1243 	if (preempt_count() != count) {
1244 		sprintf(msgbuf, "preemption imbalance ");
1245 		preempt_count_set(count);
1246 	}
1247 	if (irqs_disabled()) {
1248 		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
1249 		local_irq_enable();
1250 	}
1251 	WARN(msgbuf[0], "initcall %pS returned with %s\n", fn, msgbuf);
1252 
1253 	add_latent_entropy();
1254 	return ret;
1255 }
1256 
1257 
1258 static initcall_entry_t *initcall_levels[] __initdata = {
1259 	__initcall0_start,
1260 	__initcall1_start,
1261 	__initcall2_start,
1262 	__initcall3_start,
1263 	__initcall4_start,
1264 	__initcall5_start,
1265 	__initcall6_start,
1266 	__initcall7_start,
1267 	__initcall_end,
1268 };
1269 
1270 /* Keep these in sync with initcalls in include/linux/init.h */
1271 static const char *initcall_level_names[] __initdata = {
1272 	"pure",
1273 	"core",
1274 	"postcore",
1275 	"arch",
1276 	"subsys",
1277 	"fs",
1278 	"device",
1279 	"late",
1280 };
1281 
1282 static int __init ignore_unknown_bootoption(char *param, char *val,
1283 			       const char *unused, void *arg)
1284 {
1285 	return 0;
1286 }
1287 
1288 static void __init do_initcall_level(int level, char *command_line)
1289 {
1290 	initcall_entry_t *fn;
1291 
1292 	parse_args(initcall_level_names[level],
1293 		   command_line, __start___param,
1294 		   __stop___param - __start___param,
1295 		   level, level,
1296 		   NULL, ignore_unknown_bootoption);
1297 
1298 	trace_initcall_level(initcall_level_names[level]);
1299 	for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
1300 		do_one_initcall(initcall_from_entry(fn));
1301 }
1302 
1303 static void __init do_initcalls(void)
1304 {
1305 	int level;
1306 	size_t len = saved_command_line_len + 1;
1307 	char *command_line;
1308 
1309 	command_line = kzalloc(len, GFP_KERNEL);
1310 	if (!command_line)
1311 		panic("%s: Failed to allocate %zu bytes\n", __func__, len);
1312 
1313 	for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++) {
1314 		/* Parser modifies command_line, restore it each time */
1315 		strcpy(command_line, saved_command_line);
1316 		do_initcall_level(level, command_line);
1317 	}
1318 
1319 	kfree(command_line);
1320 }
1321 
1322 /*
1323  * Ok, the machine is now initialized. None of the devices
1324  * have been touched yet, but the CPU subsystem is up and
1325  * running, and memory and process management works.
1326  *
1327  * Now we can finally start doing some real work..
1328  */
1329 static void __init do_basic_setup(void)
1330 {
1331 	cpuset_init_smp();
1332 	driver_init();
1333 	init_irq_proc();
1334 	do_ctors();
1335 	do_initcalls();
1336 }
1337 
1338 static void __init do_pre_smp_initcalls(void)
1339 {
1340 	initcall_entry_t *fn;
1341 
1342 	trace_initcall_level("early");
1343 	for (fn = __initcall_start; fn < __initcall0_start; fn++)
1344 		do_one_initcall(initcall_from_entry(fn));
1345 }
1346 
1347 static int run_init_process(const char *init_filename)
1348 {
1349 	const char *const *p;
1350 
1351 	argv_init[0] = init_filename;
1352 	pr_info("Run %s as init process\n", init_filename);
1353 	pr_debug("  with arguments:\n");
1354 	for (p = argv_init; *p; p++)
1355 		pr_debug("    %s\n", *p);
1356 	pr_debug("  with environment:\n");
1357 	for (p = envp_init; *p; p++)
1358 		pr_debug("    %s\n", *p);
1359 	return kernel_execve(init_filename, argv_init, envp_init);
1360 }
1361 
1362 static int try_to_run_init_process(const char *init_filename)
1363 {
1364 	int ret;
1365 
1366 	ret = run_init_process(init_filename);
1367 
1368 	if (ret && ret != -ENOENT) {
1369 		pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
1370 		       init_filename, ret);
1371 	}
1372 
1373 	return ret;
1374 }
1375 
1376 static noinline void __init kernel_init_freeable(void);
1377 
1378 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
1379 bool rodata_enabled __ro_after_init = true;
1380 
1381 #ifndef arch_parse_debug_rodata
1382 static inline bool arch_parse_debug_rodata(char *str) { return false; }
1383 #endif
1384 
1385 static int __init set_debug_rodata(char *str)
1386 {
1387 	if (arch_parse_debug_rodata(str))
1388 		return 0;
1389 
1390 	if (str && !strcmp(str, "on"))
1391 		rodata_enabled = true;
1392 	else if (str && !strcmp(str, "off"))
1393 		rodata_enabled = false;
1394 	else
1395 		pr_warn("Invalid option string for rodata: '%s'\n", str);
1396 	return 0;
1397 }
1398 early_param("rodata", set_debug_rodata);
1399 #endif
1400 
1401 static void mark_readonly(void)
1402 {
1403 	if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) && rodata_enabled) {
1404 		/*
1405 		 * load_module() results in W+X mappings, which are cleaned
1406 		 * up with init_free_wq. Let's make sure that queued work is
1407 		 * flushed so that we don't hit false positives looking for
1408 		 * insecure pages which are W+X.
1409 		 */
1410 		flush_module_init_free_work();
1411 		mark_rodata_ro();
1412 		debug_checkwx();
1413 		rodata_test();
1414 	} else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) {
1415 		pr_info("Kernel memory protection disabled.\n");
1416 	} else if (IS_ENABLED(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)) {
1417 		pr_warn("Kernel memory protection not selected by kernel config.\n");
1418 	} else {
1419 		pr_warn("This architecture does not have kernel memory protection.\n");
1420 	}
1421 }
1422 
1423 void __weak free_initmem(void)
1424 {
1425 	free_initmem_default(POISON_FREE_INITMEM);
1426 }
1427 
1428 static int __ref kernel_init(void *unused)
1429 {
1430 	int ret;
1431 
1432 	/*
1433 	 * Wait until kthreadd is all set-up.
1434 	 */
1435 	wait_for_completion(&kthreadd_done);
1436 
1437 	kernel_init_freeable();
1438 	/* need to finish all async __init code before freeing the memory */
1439 	async_synchronize_full();
1440 
1441 	system_state = SYSTEM_FREEING_INITMEM;
1442 	kprobe_free_init_mem();
1443 	ftrace_free_init_mem();
1444 	kgdb_free_init_mem();
1445 	exit_boot_config();
1446 	free_initmem();
1447 	mark_readonly();
1448 
1449 	/*
1450 	 * Kernel mappings are now finalized - update the userspace page-table
1451 	 * to finalize PTI.
1452 	 */
1453 	pti_finalize();
1454 
1455 	system_state = SYSTEM_RUNNING;
1456 	numa_default_policy();
1457 
1458 	rcu_end_inkernel_boot();
1459 
1460 	do_sysctl_args();
1461 
1462 	if (ramdisk_execute_command) {
1463 		ret = run_init_process(ramdisk_execute_command);
1464 		if (!ret)
1465 			return 0;
1466 		pr_err("Failed to execute %s (error %d)\n",
1467 		       ramdisk_execute_command, ret);
1468 	}
1469 
1470 	/*
1471 	 * We try each of these until one succeeds.
1472 	 *
1473 	 * The Bourne shell can be used instead of init if we are
1474 	 * trying to recover a really broken machine.
1475 	 */
1476 	if (execute_command) {
1477 		ret = run_init_process(execute_command);
1478 		if (!ret)
1479 			return 0;
1480 		panic("Requested init %s failed (error %d).",
1481 		      execute_command, ret);
1482 	}
1483 
1484 	if (CONFIG_DEFAULT_INIT[0] != '\0') {
1485 		ret = run_init_process(CONFIG_DEFAULT_INIT);
1486 		if (ret)
1487 			pr_err("Default init %s failed (error %d)\n",
1488 			       CONFIG_DEFAULT_INIT, ret);
1489 		else
1490 			return 0;
1491 	}
1492 
1493 	if (!try_to_run_init_process("/sbin/init") ||
1494 	    !try_to_run_init_process("/etc/init") ||
1495 	    !try_to_run_init_process("/bin/init") ||
1496 	    !try_to_run_init_process("/bin/sh"))
1497 		return 0;
1498 
1499 	panic("No working init found.  Try passing init= option to kernel. "
1500 	      "See Linux Documentation/admin-guide/init.rst for guidance.");
1501 }
1502 
1503 /* Open /dev/console, for stdin/stdout/stderr, this should never fail */
1504 void __init console_on_rootfs(void)
1505 {
1506 	struct file *file = filp_open("/dev/console", O_RDWR, 0);
1507 
1508 	if (IS_ERR(file)) {
1509 		pr_err("Warning: unable to open an initial console.\n");
1510 		return;
1511 	}
1512 	init_dup(file);
1513 	init_dup(file);
1514 	init_dup(file);
1515 	fput(file);
1516 }
1517 
1518 static noinline void __init kernel_init_freeable(void)
1519 {
1520 	/* Now the scheduler is fully set up and can do blocking allocations */
1521 	gfp_allowed_mask = __GFP_BITS_MASK;
1522 
1523 	/*
1524 	 * init can allocate pages on any node
1525 	 */
1526 	set_mems_allowed(node_states[N_MEMORY]);
1527 
1528 	cad_pid = get_pid(task_pid(current));
1529 
1530 	smp_prepare_cpus(setup_max_cpus);
1531 
1532 	workqueue_init();
1533 
1534 	init_mm_internals();
1535 
1536 	rcu_init_tasks_generic();
1537 	do_pre_smp_initcalls();
1538 	lockup_detector_init();
1539 
1540 	smp_init();
1541 	sched_init_smp();
1542 
1543 	workqueue_init_topology();
1544 	async_init();
1545 	padata_init();
1546 	page_alloc_init_late();
1547 
1548 	do_basic_setup();
1549 
1550 	kunit_run_all_tests();
1551 
1552 	wait_for_initramfs();
1553 	console_on_rootfs();
1554 
1555 	/*
1556 	 * check if there is an early userspace init.  If yes, let it do all
1557 	 * the work
1558 	 */
1559 	if (init_eaccess(ramdisk_execute_command) != 0) {
1560 		ramdisk_execute_command = NULL;
1561 		prepare_namespace();
1562 	}
1563 
1564 	/*
1565 	 * Ok, we have completed the initial bootup, and
1566 	 * we're essentially up and running. Get rid of the
1567 	 * initmem segments and start the user-mode stuff..
1568 	 *
1569 	 * rootfs is available now, try loading the public keys
1570 	 * and default modules
1571 	 */
1572 
1573 	integrity_load_keys();
1574 }
1575