xref: /openbmc/linux/init/main.c (revision 275876e2)
1 /*
2  *  linux/init/main.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  *
6  *  GK 2/5/95  -  Changed to support mounting root fs via NFS
7  *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
8  *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
9  *  Simplified starting of init:  Michael A. Griffith <grif@acm.org>
10  */
11 
12 #define DEBUG		/* Enable initcall_debug */
13 
14 #include <linux/types.h>
15 #include <linux/module.h>
16 #include <linux/proc_fs.h>
17 #include <linux/kernel.h>
18 #include <linux/syscalls.h>
19 #include <linux/stackprotector.h>
20 #include <linux/string.h>
21 #include <linux/ctype.h>
22 #include <linux/delay.h>
23 #include <linux/ioport.h>
24 #include <linux/init.h>
25 #include <linux/initrd.h>
26 #include <linux/bootmem.h>
27 #include <linux/acpi.h>
28 #include <linux/tty.h>
29 #include <linux/percpu.h>
30 #include <linux/kmod.h>
31 #include <linux/vmalloc.h>
32 #include <linux/kernel_stat.h>
33 #include <linux/start_kernel.h>
34 #include <linux/security.h>
35 #include <linux/smp.h>
36 #include <linux/profile.h>
37 #include <linux/rcupdate.h>
38 #include <linux/moduleparam.h>
39 #include <linux/kallsyms.h>
40 #include <linux/writeback.h>
41 #include <linux/cpu.h>
42 #include <linux/cpuset.h>
43 #include <linux/cgroup.h>
44 #include <linux/efi.h>
45 #include <linux/tick.h>
46 #include <linux/interrupt.h>
47 #include <linux/taskstats_kern.h>
48 #include <linux/delayacct.h>
49 #include <linux/unistd.h>
50 #include <linux/rmap.h>
51 #include <linux/mempolicy.h>
52 #include <linux/key.h>
53 #include <linux/buffer_head.h>
54 #include <linux/page_cgroup.h>
55 #include <linux/debug_locks.h>
56 #include <linux/debugobjects.h>
57 #include <linux/lockdep.h>
58 #include <linux/kmemleak.h>
59 #include <linux/pid_namespace.h>
60 #include <linux/device.h>
61 #include <linux/kthread.h>
62 #include <linux/sched.h>
63 #include <linux/signal.h>
64 #include <linux/idr.h>
65 #include <linux/kgdb.h>
66 #include <linux/ftrace.h>
67 #include <linux/async.h>
68 #include <linux/kmemcheck.h>
69 #include <linux/sfi.h>
70 #include <linux/shmem_fs.h>
71 #include <linux/slab.h>
72 #include <linux/perf_event.h>
73 #include <linux/file.h>
74 #include <linux/ptrace.h>
75 #include <linux/blkdev.h>
76 #include <linux/elevator.h>
77 #include <linux/sched_clock.h>
78 #include <linux/context_tracking.h>
79 #include <linux/random.h>
80 #include <linux/list.h>
81 
82 #include <asm/io.h>
83 #include <asm/bugs.h>
84 #include <asm/setup.h>
85 #include <asm/sections.h>
86 #include <asm/cacheflush.h>
87 
88 #ifdef CONFIG_X86_LOCAL_APIC
89 #include <asm/smp.h>
90 #endif
91 
92 static int kernel_init(void *);
93 
94 extern void init_IRQ(void);
95 extern void fork_init(unsigned long);
96 extern void radix_tree_init(void);
97 #ifndef CONFIG_DEBUG_RODATA
98 static inline void mark_rodata_ro(void) { }
99 #endif
100 
101 /*
102  * Debug helper: via this flag we know that we are in 'early bootup code'
103  * where only the boot processor is running with IRQ disabled.  This means
104  * two things - IRQ must not be enabled before the flag is cleared and some
105  * operations which are not allowed with IRQ disabled are allowed while the
106  * flag is set.
107  */
108 bool early_boot_irqs_disabled __read_mostly;
109 
110 enum system_states system_state __read_mostly;
111 EXPORT_SYMBOL(system_state);
112 
113 /*
114  * Boot command-line arguments
115  */
116 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
117 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
118 
119 extern void time_init(void);
120 /* Default late time init is NULL. archs can override this later. */
121 void (*__initdata late_time_init)(void);
122 
123 /* Untouched command line saved by arch-specific code. */
124 char __initdata boot_command_line[COMMAND_LINE_SIZE];
125 /* Untouched saved command line (eg. for /proc) */
126 char *saved_command_line;
127 /* Command line for parameter parsing */
128 static char *static_command_line;
129 /* Command line for per-initcall parameter parsing */
130 static char *initcall_command_line;
131 
132 static char *execute_command;
133 static char *ramdisk_execute_command;
134 
135 /*
136  * Used to generate warnings if static_key manipulation functions are used
137  * before jump_label_init is called.
138  */
139 bool static_key_initialized __read_mostly;
140 EXPORT_SYMBOL_GPL(static_key_initialized);
141 
142 /*
143  * If set, this is an indication to the drivers that reset the underlying
144  * device before going ahead with the initialization otherwise driver might
145  * rely on the BIOS and skip the reset operation.
146  *
147  * This is useful if kernel is booting in an unreliable environment.
148  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
149  * skipped and devices will be in unknown state.
150  */
151 unsigned int reset_devices;
152 EXPORT_SYMBOL(reset_devices);
153 
154 static int __init set_reset_devices(char *str)
155 {
156 	reset_devices = 1;
157 	return 1;
158 }
159 
160 __setup("reset_devices", set_reset_devices);
161 
162 static const char *argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
163 const char *envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
164 static const char *panic_later, *panic_param;
165 
166 extern const struct obs_kernel_param __setup_start[], __setup_end[];
167 
168 static int __init obsolete_checksetup(char *line)
169 {
170 	const struct obs_kernel_param *p;
171 	int had_early_param = 0;
172 
173 	p = __setup_start;
174 	do {
175 		int n = strlen(p->str);
176 		if (parameqn(line, p->str, n)) {
177 			if (p->early) {
178 				/* Already done in parse_early_param?
179 				 * (Needs exact match on param part).
180 				 * Keep iterating, as we can have early
181 				 * params and __setups of same names 8( */
182 				if (line[n] == '\0' || line[n] == '=')
183 					had_early_param = 1;
184 			} else if (!p->setup_func) {
185 				pr_warn("Parameter %s is obsolete, ignored\n",
186 					p->str);
187 				return 1;
188 			} else if (p->setup_func(line + n))
189 				return 1;
190 		}
191 		p++;
192 	} while (p < __setup_end);
193 
194 	return had_early_param;
195 }
196 
197 /*
198  * This should be approx 2 Bo*oMips to start (note initial shift), and will
199  * still work even if initially too large, it will just take slightly longer
200  */
201 unsigned long loops_per_jiffy = (1<<12);
202 EXPORT_SYMBOL(loops_per_jiffy);
203 
204 static int __init debug_kernel(char *str)
205 {
206 	console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
207 	return 0;
208 }
209 
210 static int __init quiet_kernel(char *str)
211 {
212 	console_loglevel = CONSOLE_LOGLEVEL_QUIET;
213 	return 0;
214 }
215 
216 early_param("debug", debug_kernel);
217 early_param("quiet", quiet_kernel);
218 
219 static int __init loglevel(char *str)
220 {
221 	int newlevel;
222 
223 	/*
224 	 * Only update loglevel value when a correct setting was passed,
225 	 * to prevent blind crashes (when loglevel being set to 0) that
226 	 * are quite hard to debug
227 	 */
228 	if (get_option(&str, &newlevel)) {
229 		console_loglevel = newlevel;
230 		return 0;
231 	}
232 
233 	return -EINVAL;
234 }
235 
236 early_param("loglevel", loglevel);
237 
238 /* Change NUL term back to "=", to make "param" the whole string. */
239 static int __init repair_env_string(char *param, char *val, const char *unused)
240 {
241 	if (val) {
242 		/* param=val or param="val"? */
243 		if (val == param+strlen(param)+1)
244 			val[-1] = '=';
245 		else if (val == param+strlen(param)+2) {
246 			val[-2] = '=';
247 			memmove(val-1, val, strlen(val)+1);
248 			val--;
249 		} else
250 			BUG();
251 	}
252 	return 0;
253 }
254 
255 /* Anything after -- gets handed straight to init. */
256 static int __init set_init_arg(char *param, char *val, const char *unused)
257 {
258 	unsigned int i;
259 
260 	if (panic_later)
261 		return 0;
262 
263 	repair_env_string(param, val, unused);
264 
265 	for (i = 0; argv_init[i]; i++) {
266 		if (i == MAX_INIT_ARGS) {
267 			panic_later = "init";
268 			panic_param = param;
269 			return 0;
270 		}
271 	}
272 	argv_init[i] = param;
273 	return 0;
274 }
275 
276 /*
277  * Unknown boot options get handed to init, unless they look like
278  * unused parameters (modprobe will find them in /proc/cmdline).
279  */
280 static int __init unknown_bootoption(char *param, char *val, const char *unused)
281 {
282 	repair_env_string(param, val, unused);
283 
284 	/* Handle obsolete-style parameters */
285 	if (obsolete_checksetup(param))
286 		return 0;
287 
288 	/* Unused module parameter. */
289 	if (strchr(param, '.') && (!val || strchr(param, '.') < val))
290 		return 0;
291 
292 	if (panic_later)
293 		return 0;
294 
295 	if (val) {
296 		/* Environment option */
297 		unsigned int i;
298 		for (i = 0; envp_init[i]; i++) {
299 			if (i == MAX_INIT_ENVS) {
300 				panic_later = "env";
301 				panic_param = param;
302 			}
303 			if (!strncmp(param, envp_init[i], val - param))
304 				break;
305 		}
306 		envp_init[i] = param;
307 	} else {
308 		/* Command line option */
309 		unsigned int i;
310 		for (i = 0; argv_init[i]; i++) {
311 			if (i == MAX_INIT_ARGS) {
312 				panic_later = "init";
313 				panic_param = param;
314 			}
315 		}
316 		argv_init[i] = param;
317 	}
318 	return 0;
319 }
320 
321 static int __init init_setup(char *str)
322 {
323 	unsigned int i;
324 
325 	execute_command = str;
326 	/*
327 	 * In case LILO is going to boot us with default command line,
328 	 * it prepends "auto" before the whole cmdline which makes
329 	 * the shell think it should execute a script with such name.
330 	 * So we ignore all arguments entered _before_ init=... [MJ]
331 	 */
332 	for (i = 1; i < MAX_INIT_ARGS; i++)
333 		argv_init[i] = NULL;
334 	return 1;
335 }
336 __setup("init=", init_setup);
337 
338 static int __init rdinit_setup(char *str)
339 {
340 	unsigned int i;
341 
342 	ramdisk_execute_command = str;
343 	/* See "auto" comment in init_setup */
344 	for (i = 1; i < MAX_INIT_ARGS; i++)
345 		argv_init[i] = NULL;
346 	return 1;
347 }
348 __setup("rdinit=", rdinit_setup);
349 
350 #ifndef CONFIG_SMP
351 static const unsigned int setup_max_cpus = NR_CPUS;
352 #ifdef CONFIG_X86_LOCAL_APIC
353 static void __init smp_init(void)
354 {
355 	APIC_init_uniprocessor();
356 }
357 #else
358 #define smp_init()	do { } while (0)
359 #endif
360 
361 static inline void setup_nr_cpu_ids(void) { }
362 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
363 #endif
364 
365 /*
366  * We need to store the untouched command line for future reference.
367  * We also need to store the touched command line since the parameter
368  * parsing is performed in place, and we should allow a component to
369  * store reference of name/value for future reference.
370  */
371 static void __init setup_command_line(char *command_line)
372 {
373 	saved_command_line =
374 		memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
375 	initcall_command_line =
376 		memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
377 	static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
378 	strcpy(saved_command_line, boot_command_line);
379 	strcpy(static_command_line, command_line);
380 }
381 
382 /*
383  * We need to finalize in a non-__init function or else race conditions
384  * between the root thread and the init thread may cause start_kernel to
385  * be reaped by free_initmem before the root thread has proceeded to
386  * cpu_idle.
387  *
388  * gcc-3.4 accidentally inlines this function, so use noinline.
389  */
390 
391 static __initdata DECLARE_COMPLETION(kthreadd_done);
392 
393 static noinline void __init_refok rest_init(void)
394 {
395 	int pid;
396 
397 	rcu_scheduler_starting();
398 	/*
399 	 * We need to spawn init first so that it obtains pid 1, however
400 	 * the init task will end up wanting to create kthreads, which, if
401 	 * we schedule it before we create kthreadd, will OOPS.
402 	 */
403 	kernel_thread(kernel_init, NULL, CLONE_FS);
404 	numa_default_policy();
405 	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
406 	rcu_read_lock();
407 	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
408 	rcu_read_unlock();
409 	complete(&kthreadd_done);
410 
411 	/*
412 	 * The boot idle thread must execute schedule()
413 	 * at least once to get things moving:
414 	 */
415 	init_idle_bootup_task(current);
416 	schedule_preempt_disabled();
417 	/* Call into cpu_idle with preempt disabled */
418 	cpu_startup_entry(CPUHP_ONLINE);
419 }
420 
421 /* Check for early params. */
422 static int __init do_early_param(char *param, char *val, const char *unused)
423 {
424 	const struct obs_kernel_param *p;
425 
426 	for (p = __setup_start; p < __setup_end; p++) {
427 		if ((p->early && parameq(param, p->str)) ||
428 		    (strcmp(param, "console") == 0 &&
429 		     strcmp(p->str, "earlycon") == 0)
430 		) {
431 			if (p->setup_func(val) != 0)
432 				pr_warn("Malformed early option '%s'\n", param);
433 		}
434 	}
435 	/* We accept everything at this stage. */
436 	return 0;
437 }
438 
439 void __init parse_early_options(char *cmdline)
440 {
441 	parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
442 }
443 
444 /* Arch code calls this early on, or if not, just before other parsing. */
445 void __init parse_early_param(void)
446 {
447 	static int done __initdata;
448 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
449 
450 	if (done)
451 		return;
452 
453 	/* All fall through to do_early_param. */
454 	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
455 	parse_early_options(tmp_cmdline);
456 	done = 1;
457 }
458 
459 /*
460  *	Activate the first processor.
461  */
462 
463 static void __init boot_cpu_init(void)
464 {
465 	int cpu = smp_processor_id();
466 	/* Mark the boot cpu "present", "online" etc for SMP and UP case */
467 	set_cpu_online(cpu, true);
468 	set_cpu_active(cpu, true);
469 	set_cpu_present(cpu, true);
470 	set_cpu_possible(cpu, true);
471 }
472 
473 void __init __weak smp_setup_processor_id(void)
474 {
475 }
476 
477 # if THREAD_SIZE >= PAGE_SIZE
478 void __init __weak thread_info_cache_init(void)
479 {
480 }
481 #endif
482 
483 /*
484  * Set up kernel memory allocators
485  */
486 static void __init mm_init(void)
487 {
488 	/*
489 	 * page_cgroup requires contiguous pages,
490 	 * bigger than MAX_ORDER unless SPARSEMEM.
491 	 */
492 	page_cgroup_init_flatmem();
493 	mem_init();
494 	kmem_cache_init();
495 	percpu_init_late();
496 	pgtable_init();
497 	vmalloc_init();
498 }
499 
500 asmlinkage __visible void __init start_kernel(void)
501 {
502 	char *command_line;
503 	char *after_dashes;
504 	extern const struct kernel_param __start___param[], __stop___param[];
505 
506 	/*
507 	 * Need to run as early as possible, to initialize the
508 	 * lockdep hash:
509 	 */
510 	lockdep_init();
511 	smp_setup_processor_id();
512 	debug_objects_early_init();
513 
514 	/*
515 	 * Set up the the initial canary ASAP:
516 	 */
517 	boot_init_stack_canary();
518 
519 	cgroup_init_early();
520 
521 	local_irq_disable();
522 	early_boot_irqs_disabled = true;
523 
524 /*
525  * Interrupts are still disabled. Do necessary setups, then
526  * enable them
527  */
528 	boot_cpu_init();
529 	page_address_init();
530 	pr_notice("%s", linux_banner);
531 	setup_arch(&command_line);
532 	mm_init_cpumask(&init_mm);
533 	setup_command_line(command_line);
534 	setup_nr_cpu_ids();
535 	setup_per_cpu_areas();
536 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
537 
538 	build_all_zonelists(NULL, NULL);
539 	page_alloc_init();
540 
541 	pr_notice("Kernel command line: %s\n", boot_command_line);
542 	parse_early_param();
543 	after_dashes = parse_args("Booting kernel",
544 				  static_command_line, __start___param,
545 				  __stop___param - __start___param,
546 				  -1, -1, &unknown_bootoption);
547 	if (after_dashes)
548 		parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
549 			   set_init_arg);
550 
551 	jump_label_init();
552 
553 	/*
554 	 * These use large bootmem allocations and must precede
555 	 * kmem_cache_init()
556 	 */
557 	setup_log_buf(0);
558 	pidhash_init();
559 	vfs_caches_init_early();
560 	sort_main_extable();
561 	trap_init();
562 	mm_init();
563 
564 	/*
565 	 * Set up the scheduler prior starting any interrupts (such as the
566 	 * timer interrupt). Full topology setup happens at smp_init()
567 	 * time - but meanwhile we still have a functioning scheduler.
568 	 */
569 	sched_init();
570 	/*
571 	 * Disable preemption - early bootup scheduling is extremely
572 	 * fragile until we cpu_idle() for the first time.
573 	 */
574 	preempt_disable();
575 	if (WARN(!irqs_disabled(),
576 		 "Interrupts were enabled *very* early, fixing it\n"))
577 		local_irq_disable();
578 	idr_init_cache();
579 	rcu_init();
580 	tick_nohz_init();
581 	context_tracking_init();
582 	radix_tree_init();
583 	/* init some links before init_ISA_irqs() */
584 	early_irq_init();
585 	init_IRQ();
586 	tick_init();
587 	init_timers();
588 	hrtimers_init();
589 	softirq_init();
590 	timekeeping_init();
591 	time_init();
592 	sched_clock_postinit();
593 	perf_event_init();
594 	profile_init();
595 	call_function_init();
596 	WARN(!irqs_disabled(), "Interrupts were enabled early\n");
597 	early_boot_irqs_disabled = false;
598 	local_irq_enable();
599 
600 	kmem_cache_init_late();
601 
602 	/*
603 	 * HACK ALERT! This is early. We're enabling the console before
604 	 * we've done PCI setups etc, and console_init() must be aware of
605 	 * this. But we do want output early, in case something goes wrong.
606 	 */
607 	console_init();
608 	if (panic_later)
609 		panic("Too many boot %s vars at `%s'", panic_later,
610 		      panic_param);
611 
612 	lockdep_info();
613 
614 	/*
615 	 * Need to run this when irqs are enabled, because it wants
616 	 * to self-test [hard/soft]-irqs on/off lock inversion bugs
617 	 * too:
618 	 */
619 	locking_selftest();
620 
621 #ifdef CONFIG_BLK_DEV_INITRD
622 	if (initrd_start && !initrd_below_start_ok &&
623 	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
624 		pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
625 		    page_to_pfn(virt_to_page((void *)initrd_start)),
626 		    min_low_pfn);
627 		initrd_start = 0;
628 	}
629 #endif
630 	page_cgroup_init();
631 	debug_objects_mem_init();
632 	kmemleak_init();
633 	setup_per_cpu_pageset();
634 	numa_policy_init();
635 	if (late_time_init)
636 		late_time_init();
637 	sched_clock_init();
638 	calibrate_delay();
639 	pidmap_init();
640 	anon_vma_init();
641 	acpi_early_init();
642 #ifdef CONFIG_X86
643 	if (efi_enabled(EFI_RUNTIME_SERVICES))
644 		efi_enter_virtual_mode();
645 #endif
646 #ifdef CONFIG_X86_ESPFIX64
647 	/* Should be run before the first non-init thread is created */
648 	init_espfix_bsp();
649 #endif
650 	thread_info_cache_init();
651 	cred_init();
652 	fork_init(totalram_pages);
653 	proc_caches_init();
654 	buffer_init();
655 	key_init();
656 	security_init();
657 	dbg_late_init();
658 	vfs_caches_init(totalram_pages);
659 	signals_init();
660 	/* rootfs populating might need page-writeback */
661 	page_writeback_init();
662 	proc_root_init();
663 	cgroup_init();
664 	cpuset_init();
665 	taskstats_init_early();
666 	delayacct_init();
667 
668 	check_bugs();
669 
670 	sfi_init_late();
671 
672 	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
673 		efi_late_init();
674 		efi_free_boot_services();
675 	}
676 
677 	ftrace_init();
678 
679 	/* Do the rest non-__init'ed, we're now alive */
680 	rest_init();
681 }
682 
683 /* Call all constructor functions linked into the kernel. */
684 static void __init do_ctors(void)
685 {
686 #ifdef CONFIG_CONSTRUCTORS
687 	ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
688 
689 	for (; fn < (ctor_fn_t *) __ctors_end; fn++)
690 		(*fn)();
691 #endif
692 }
693 
694 bool initcall_debug;
695 core_param(initcall_debug, initcall_debug, bool, 0644);
696 
697 #ifdef CONFIG_KALLSYMS
698 struct blacklist_entry {
699 	struct list_head next;
700 	char *buf;
701 };
702 
703 static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
704 
705 static int __init initcall_blacklist(char *str)
706 {
707 	char *str_entry;
708 	struct blacklist_entry *entry;
709 
710 	/* str argument is a comma-separated list of functions */
711 	do {
712 		str_entry = strsep(&str, ",");
713 		if (str_entry) {
714 			pr_debug("blacklisting initcall %s\n", str_entry);
715 			entry = alloc_bootmem(sizeof(*entry));
716 			entry->buf = alloc_bootmem(strlen(str_entry) + 1);
717 			strcpy(entry->buf, str_entry);
718 			list_add(&entry->next, &blacklisted_initcalls);
719 		}
720 	} while (str_entry);
721 
722 	return 0;
723 }
724 
725 static bool __init_or_module initcall_blacklisted(initcall_t fn)
726 {
727 	struct list_head *tmp;
728 	struct blacklist_entry *entry;
729 	char *fn_name;
730 
731 	fn_name = kasprintf(GFP_KERNEL, "%pf", fn);
732 	if (!fn_name)
733 		return false;
734 
735 	list_for_each(tmp, &blacklisted_initcalls) {
736 		entry = list_entry(tmp, struct blacklist_entry, next);
737 		if (!strcmp(fn_name, entry->buf)) {
738 			pr_debug("initcall %s blacklisted\n", fn_name);
739 			kfree(fn_name);
740 			return true;
741 		}
742 	}
743 
744 	kfree(fn_name);
745 	return false;
746 }
747 #else
748 static int __init initcall_blacklist(char *str)
749 {
750 	pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
751 	return 0;
752 }
753 
754 static bool __init_or_module initcall_blacklisted(initcall_t fn)
755 {
756 	return false;
757 }
758 #endif
759 __setup("initcall_blacklist=", initcall_blacklist);
760 
761 static int __init_or_module do_one_initcall_debug(initcall_t fn)
762 {
763 	ktime_t calltime, delta, rettime;
764 	unsigned long long duration;
765 	int ret;
766 
767 	printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
768 	calltime = ktime_get();
769 	ret = fn();
770 	rettime = ktime_get();
771 	delta = ktime_sub(rettime, calltime);
772 	duration = (unsigned long long) ktime_to_ns(delta) >> 10;
773 	printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n",
774 		 fn, ret, duration);
775 
776 	return ret;
777 }
778 
779 int __init_or_module do_one_initcall(initcall_t fn)
780 {
781 	int count = preempt_count();
782 	int ret;
783 	char msgbuf[64];
784 
785 	if (initcall_blacklisted(fn))
786 		return -EPERM;
787 
788 	if (initcall_debug)
789 		ret = do_one_initcall_debug(fn);
790 	else
791 		ret = fn();
792 
793 	msgbuf[0] = 0;
794 
795 	if (preempt_count() != count) {
796 		sprintf(msgbuf, "preemption imbalance ");
797 		preempt_count_set(count);
798 	}
799 	if (irqs_disabled()) {
800 		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
801 		local_irq_enable();
802 	}
803 	WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
804 
805 	return ret;
806 }
807 
808 
809 extern initcall_t __initcall_start[];
810 extern initcall_t __initcall0_start[];
811 extern initcall_t __initcall1_start[];
812 extern initcall_t __initcall2_start[];
813 extern initcall_t __initcall3_start[];
814 extern initcall_t __initcall4_start[];
815 extern initcall_t __initcall5_start[];
816 extern initcall_t __initcall6_start[];
817 extern initcall_t __initcall7_start[];
818 extern initcall_t __initcall_end[];
819 
820 static initcall_t *initcall_levels[] __initdata = {
821 	__initcall0_start,
822 	__initcall1_start,
823 	__initcall2_start,
824 	__initcall3_start,
825 	__initcall4_start,
826 	__initcall5_start,
827 	__initcall6_start,
828 	__initcall7_start,
829 	__initcall_end,
830 };
831 
832 /* Keep these in sync with initcalls in include/linux/init.h */
833 static char *initcall_level_names[] __initdata = {
834 	"early",
835 	"core",
836 	"postcore",
837 	"arch",
838 	"subsys",
839 	"fs",
840 	"device",
841 	"late",
842 };
843 
844 static void __init do_initcall_level(int level)
845 {
846 	extern const struct kernel_param __start___param[], __stop___param[];
847 	initcall_t *fn;
848 
849 	strcpy(initcall_command_line, saved_command_line);
850 	parse_args(initcall_level_names[level],
851 		   initcall_command_line, __start___param,
852 		   __stop___param - __start___param,
853 		   level, level,
854 		   &repair_env_string);
855 
856 	for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
857 		do_one_initcall(*fn);
858 }
859 
860 static void __init do_initcalls(void)
861 {
862 	int level;
863 
864 	for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
865 		do_initcall_level(level);
866 }
867 
868 /*
869  * Ok, the machine is now initialized. None of the devices
870  * have been touched yet, but the CPU subsystem is up and
871  * running, and memory and process management works.
872  *
873  * Now we can finally start doing some real work..
874  */
875 static void __init do_basic_setup(void)
876 {
877 	cpuset_init_smp();
878 	usermodehelper_init();
879 	shmem_init();
880 	driver_init();
881 	init_irq_proc();
882 	do_ctors();
883 	usermodehelper_enable();
884 	do_initcalls();
885 	random_int_secret_init();
886 }
887 
888 static void __init do_pre_smp_initcalls(void)
889 {
890 	initcall_t *fn;
891 
892 	for (fn = __initcall_start; fn < __initcall0_start; fn++)
893 		do_one_initcall(*fn);
894 }
895 
896 /*
897  * This function requests modules which should be loaded by default and is
898  * called twice right after initrd is mounted and right before init is
899  * exec'd.  If such modules are on either initrd or rootfs, they will be
900  * loaded before control is passed to userland.
901  */
902 void __init load_default_modules(void)
903 {
904 	load_default_elevator_module();
905 }
906 
907 static int run_init_process(const char *init_filename)
908 {
909 	argv_init[0] = init_filename;
910 	return do_execve(getname_kernel(init_filename),
911 		(const char __user *const __user *)argv_init,
912 		(const char __user *const __user *)envp_init);
913 }
914 
915 static int try_to_run_init_process(const char *init_filename)
916 {
917 	int ret;
918 
919 	ret = run_init_process(init_filename);
920 
921 	if (ret && ret != -ENOENT) {
922 		pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
923 		       init_filename, ret);
924 	}
925 
926 	return ret;
927 }
928 
929 static noinline void __init kernel_init_freeable(void);
930 
931 static int __ref kernel_init(void *unused)
932 {
933 	int ret;
934 
935 	kernel_init_freeable();
936 	/* need to finish all async __init code before freeing the memory */
937 	async_synchronize_full();
938 	free_initmem();
939 	mark_rodata_ro();
940 	system_state = SYSTEM_RUNNING;
941 	numa_default_policy();
942 
943 	flush_delayed_fput();
944 
945 	if (ramdisk_execute_command) {
946 		ret = run_init_process(ramdisk_execute_command);
947 		if (!ret)
948 			return 0;
949 		pr_err("Failed to execute %s (error %d)\n",
950 		       ramdisk_execute_command, ret);
951 	}
952 
953 	/*
954 	 * We try each of these until one succeeds.
955 	 *
956 	 * The Bourne shell can be used instead of init if we are
957 	 * trying to recover a really broken machine.
958 	 */
959 	if (execute_command) {
960 		ret = run_init_process(execute_command);
961 		if (!ret)
962 			return 0;
963 		pr_err("Failed to execute %s (error %d).  Attempting defaults...\n",
964 			execute_command, ret);
965 	}
966 	if (!try_to_run_init_process("/sbin/init") ||
967 	    !try_to_run_init_process("/etc/init") ||
968 	    !try_to_run_init_process("/bin/init") ||
969 	    !try_to_run_init_process("/bin/sh"))
970 		return 0;
971 
972 	panic("No working init found.  Try passing init= option to kernel. "
973 	      "See Linux Documentation/init.txt for guidance.");
974 }
975 
976 static noinline void __init kernel_init_freeable(void)
977 {
978 	/*
979 	 * Wait until kthreadd is all set-up.
980 	 */
981 	wait_for_completion(&kthreadd_done);
982 
983 	/* Now the scheduler is fully set up and can do blocking allocations */
984 	gfp_allowed_mask = __GFP_BITS_MASK;
985 
986 	/*
987 	 * init can allocate pages on any node
988 	 */
989 	set_mems_allowed(node_states[N_MEMORY]);
990 	/*
991 	 * init can run on any cpu.
992 	 */
993 	set_cpus_allowed_ptr(current, cpu_all_mask);
994 
995 	cad_pid = task_pid(current);
996 
997 	smp_prepare_cpus(setup_max_cpus);
998 
999 	do_pre_smp_initcalls();
1000 	lockup_detector_init();
1001 
1002 	smp_init();
1003 	sched_init_smp();
1004 
1005 	do_basic_setup();
1006 
1007 	/* Open the /dev/console on the rootfs, this should never fail */
1008 	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
1009 		pr_err("Warning: unable to open an initial console.\n");
1010 
1011 	(void) sys_dup(0);
1012 	(void) sys_dup(0);
1013 	/*
1014 	 * check if there is an early userspace init.  If yes, let it do all
1015 	 * the work
1016 	 */
1017 
1018 	if (!ramdisk_execute_command)
1019 		ramdisk_execute_command = "/init";
1020 
1021 	if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
1022 		ramdisk_execute_command = NULL;
1023 		prepare_namespace();
1024 	}
1025 
1026 	/*
1027 	 * Ok, we have completed the initial bootup, and
1028 	 * we're essentially up and running. Get rid of the
1029 	 * initmem segments and start the user-mode stuff..
1030 	 */
1031 
1032 	/* rootfs is available now, try loading default modules */
1033 	load_default_modules();
1034 }
1035