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