xref: /openbmc/linux/init/main.c (revision b6dcefde)
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 #include <linux/types.h>
13 #include <linux/module.h>
14 #include <linux/proc_fs.h>
15 #include <linux/kernel.h>
16 #include <linux/syscalls.h>
17 #include <linux/stackprotector.h>
18 #include <linux/string.h>
19 #include <linux/ctype.h>
20 #include <linux/delay.h>
21 #include <linux/ioport.h>
22 #include <linux/init.h>
23 #include <linux/smp_lock.h>
24 #include <linux/initrd.h>
25 #include <linux/bootmem.h>
26 #include <linux/acpi.h>
27 #include <linux/tty.h>
28 #include <linux/gfp.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/workqueue.h>
37 #include <linux/profile.h>
38 #include <linux/rcupdate.h>
39 #include <linux/moduleparam.h>
40 #include <linux/kallsyms.h>
41 #include <linux/writeback.h>
42 #include <linux/cpu.h>
43 #include <linux/cpuset.h>
44 #include <linux/cgroup.h>
45 #include <linux/efi.h>
46 #include <linux/tick.h>
47 #include <linux/interrupt.h>
48 #include <linux/taskstats_kern.h>
49 #include <linux/delayacct.h>
50 #include <linux/unistd.h>
51 #include <linux/rmap.h>
52 #include <linux/mempolicy.h>
53 #include <linux/key.h>
54 #include <linux/buffer_head.h>
55 #include <linux/page_cgroup.h>
56 #include <linux/debug_locks.h>
57 #include <linux/debugobjects.h>
58 #include <linux/lockdep.h>
59 #include <linux/kmemleak.h>
60 #include <linux/pid_namespace.h>
61 #include <linux/device.h>
62 #include <linux/kthread.h>
63 #include <linux/sched.h>
64 #include <linux/signal.h>
65 #include <linux/idr.h>
66 #include <linux/ftrace.h>
67 #include <linux/async.h>
68 #include <linux/kmemcheck.h>
69 #include <linux/kmemtrace.h>
70 #include <linux/sfi.h>
71 #include <linux/shmem_fs.h>
72 #include <trace/boot.h>
73 
74 #include <asm/io.h>
75 #include <asm/bugs.h>
76 #include <asm/setup.h>
77 #include <asm/sections.h>
78 #include <asm/cacheflush.h>
79 
80 #ifdef CONFIG_X86_LOCAL_APIC
81 #include <asm/smp.h>
82 #endif
83 
84 static int kernel_init(void *);
85 
86 extern void init_IRQ(void);
87 extern void fork_init(unsigned long);
88 extern void mca_init(void);
89 extern void sbus_init(void);
90 extern void prio_tree_init(void);
91 extern void radix_tree_init(void);
92 extern void free_initmem(void);
93 #ifndef CONFIG_DEBUG_RODATA
94 static inline void mark_rodata_ro(void) { }
95 #endif
96 
97 #ifdef CONFIG_TC
98 extern void tc_init(void);
99 #endif
100 
101 enum system_states system_state __read_mostly;
102 EXPORT_SYMBOL(system_state);
103 
104 /*
105  * Boot command-line arguments
106  */
107 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
108 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
109 
110 extern void time_init(void);
111 /* Default late time init is NULL. archs can override this later. */
112 void (*__initdata late_time_init)(void);
113 extern void softirq_init(void);
114 
115 /* Untouched command line saved by arch-specific code. */
116 char __initdata boot_command_line[COMMAND_LINE_SIZE];
117 /* Untouched saved command line (eg. for /proc) */
118 char *saved_command_line;
119 /* Command line for parameter parsing */
120 static char *static_command_line;
121 
122 static char *execute_command;
123 static char *ramdisk_execute_command;
124 
125 #ifdef CONFIG_SMP
126 /* Setup configured maximum number of CPUs to activate */
127 unsigned int __initdata setup_max_cpus = NR_CPUS;
128 
129 /*
130  * Setup routine for controlling SMP activation
131  *
132  * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
133  * activation entirely (the MPS table probe still happens, though).
134  *
135  * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
136  * greater than 0, limits the maximum number of CPUs activated in
137  * SMP mode to <NUM>.
138  */
139 
140 void __weak arch_disable_smp_support(void) { }
141 
142 static int __init nosmp(char *str)
143 {
144 	setup_max_cpus = 0;
145 	arch_disable_smp_support();
146 
147 	return 0;
148 }
149 
150 early_param("nosmp", nosmp);
151 
152 static int __init maxcpus(char *str)
153 {
154 	get_option(&str, &setup_max_cpus);
155 	if (setup_max_cpus == 0)
156 		arch_disable_smp_support();
157 
158 	return 0;
159 }
160 
161 early_param("maxcpus", maxcpus);
162 #else
163 const unsigned int setup_max_cpus = NR_CPUS;
164 #endif
165 
166 /*
167  * If set, this is an indication to the drivers that reset the underlying
168  * device before going ahead with the initialization otherwise driver might
169  * rely on the BIOS and skip the reset operation.
170  *
171  * This is useful if kernel is booting in an unreliable environment.
172  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
173  * skipped and devices will be in unknown state.
174  */
175 unsigned int reset_devices;
176 EXPORT_SYMBOL(reset_devices);
177 
178 static int __init set_reset_devices(char *str)
179 {
180 	reset_devices = 1;
181 	return 1;
182 }
183 
184 __setup("reset_devices", set_reset_devices);
185 
186 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
187 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
188 static const char *panic_later, *panic_param;
189 
190 extern struct obs_kernel_param __setup_start[], __setup_end[];
191 
192 static int __init obsolete_checksetup(char *line)
193 {
194 	struct obs_kernel_param *p;
195 	int had_early_param = 0;
196 
197 	p = __setup_start;
198 	do {
199 		int n = strlen(p->str);
200 		if (!strncmp(line, p->str, n)) {
201 			if (p->early) {
202 				/* Already done in parse_early_param?
203 				 * (Needs exact match on param part).
204 				 * Keep iterating, as we can have early
205 				 * params and __setups of same names 8( */
206 				if (line[n] == '\0' || line[n] == '=')
207 					had_early_param = 1;
208 			} else if (!p->setup_func) {
209 				printk(KERN_WARNING "Parameter %s is obsolete,"
210 				       " ignored\n", p->str);
211 				return 1;
212 			} else if (p->setup_func(line + n))
213 				return 1;
214 		}
215 		p++;
216 	} while (p < __setup_end);
217 
218 	return had_early_param;
219 }
220 
221 /*
222  * This should be approx 2 Bo*oMips to start (note initial shift), and will
223  * still work even if initially too large, it will just take slightly longer
224  */
225 unsigned long loops_per_jiffy = (1<<12);
226 
227 EXPORT_SYMBOL(loops_per_jiffy);
228 
229 static int __init debug_kernel(char *str)
230 {
231 	console_loglevel = 10;
232 	return 0;
233 }
234 
235 static int __init quiet_kernel(char *str)
236 {
237 	console_loglevel = 4;
238 	return 0;
239 }
240 
241 early_param("debug", debug_kernel);
242 early_param("quiet", quiet_kernel);
243 
244 static int __init loglevel(char *str)
245 {
246 	get_option(&str, &console_loglevel);
247 	return 0;
248 }
249 
250 early_param("loglevel", loglevel);
251 
252 /*
253  * Unknown boot options get handed to init, unless they look like
254  * unused parameters (modprobe will find them in /proc/cmdline).
255  */
256 static int __init unknown_bootoption(char *param, char *val)
257 {
258 	/* Change NUL term back to "=", to make "param" the whole string. */
259 	if (val) {
260 		/* param=val or param="val"? */
261 		if (val == param+strlen(param)+1)
262 			val[-1] = '=';
263 		else if (val == param+strlen(param)+2) {
264 			val[-2] = '=';
265 			memmove(val-1, val, strlen(val)+1);
266 			val--;
267 		} else
268 			BUG();
269 	}
270 
271 	/* Handle obsolete-style parameters */
272 	if (obsolete_checksetup(param))
273 		return 0;
274 
275 	/* Unused module parameter. */
276 	if (strchr(param, '.') && (!val || strchr(param, '.') < val))
277 		return 0;
278 
279 	if (panic_later)
280 		return 0;
281 
282 	if (val) {
283 		/* Environment option */
284 		unsigned int i;
285 		for (i = 0; envp_init[i]; i++) {
286 			if (i == MAX_INIT_ENVS) {
287 				panic_later = "Too many boot env vars at `%s'";
288 				panic_param = param;
289 			}
290 			if (!strncmp(param, envp_init[i], val - param))
291 				break;
292 		}
293 		envp_init[i] = param;
294 	} else {
295 		/* Command line option */
296 		unsigned int i;
297 		for (i = 0; argv_init[i]; i++) {
298 			if (i == MAX_INIT_ARGS) {
299 				panic_later = "Too many boot init vars at `%s'";
300 				panic_param = param;
301 			}
302 		}
303 		argv_init[i] = param;
304 	}
305 	return 0;
306 }
307 
308 #ifdef CONFIG_DEBUG_PAGEALLOC
309 int __read_mostly debug_pagealloc_enabled = 0;
310 #endif
311 
312 static int __init init_setup(char *str)
313 {
314 	unsigned int i;
315 
316 	execute_command = str;
317 	/*
318 	 * In case LILO is going to boot us with default command line,
319 	 * it prepends "auto" before the whole cmdline which makes
320 	 * the shell think it should execute a script with such name.
321 	 * So we ignore all arguments entered _before_ init=... [MJ]
322 	 */
323 	for (i = 1; i < MAX_INIT_ARGS; i++)
324 		argv_init[i] = NULL;
325 	return 1;
326 }
327 __setup("init=", init_setup);
328 
329 static int __init rdinit_setup(char *str)
330 {
331 	unsigned int i;
332 
333 	ramdisk_execute_command = str;
334 	/* See "auto" comment in init_setup */
335 	for (i = 1; i < MAX_INIT_ARGS; i++)
336 		argv_init[i] = NULL;
337 	return 1;
338 }
339 __setup("rdinit=", rdinit_setup);
340 
341 #ifndef CONFIG_SMP
342 
343 #ifdef CONFIG_X86_LOCAL_APIC
344 static void __init smp_init(void)
345 {
346 	APIC_init_uniprocessor();
347 }
348 #else
349 #define smp_init()	do { } while (0)
350 #endif
351 
352 static inline void setup_nr_cpu_ids(void) { }
353 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
354 
355 #else
356 
357 /* Setup number of possible processor ids */
358 int nr_cpu_ids __read_mostly = NR_CPUS;
359 EXPORT_SYMBOL(nr_cpu_ids);
360 
361 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
362 static void __init setup_nr_cpu_ids(void)
363 {
364 	nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
365 }
366 
367 /* Called by boot processor to activate the rest. */
368 static void __init smp_init(void)
369 {
370 	unsigned int cpu;
371 
372 	/* FIXME: This should be done in userspace --RR */
373 	for_each_present_cpu(cpu) {
374 		if (num_online_cpus() >= setup_max_cpus)
375 			break;
376 		if (!cpu_online(cpu))
377 			cpu_up(cpu);
378 	}
379 
380 	/* Any cleanup work */
381 	printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
382 	smp_cpus_done(setup_max_cpus);
383 }
384 
385 #endif
386 
387 /*
388  * We need to store the untouched command line for future reference.
389  * We also need to store the touched command line since the parameter
390  * parsing is performed in place, and we should allow a component to
391  * store reference of name/value for future reference.
392  */
393 static void __init setup_command_line(char *command_line)
394 {
395 	saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
396 	static_command_line = alloc_bootmem(strlen (command_line)+1);
397 	strcpy (saved_command_line, boot_command_line);
398 	strcpy (static_command_line, command_line);
399 }
400 
401 /*
402  * We need to finalize in a non-__init function or else race conditions
403  * between the root thread and the init thread may cause start_kernel to
404  * be reaped by free_initmem before the root thread has proceeded to
405  * cpu_idle.
406  *
407  * gcc-3.4 accidentally inlines this function, so use noinline.
408  */
409 
410 static noinline void __init_refok rest_init(void)
411 	__releases(kernel_lock)
412 {
413 	int pid;
414 
415 	rcu_scheduler_starting();
416 	kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
417 	numa_default_policy();
418 	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
419 	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
420 	unlock_kernel();
421 
422 	/*
423 	 * The boot idle thread must execute schedule()
424 	 * at least once to get things moving:
425 	 */
426 	init_idle_bootup_task(current);
427 	preempt_enable_no_resched();
428 	schedule();
429 	preempt_disable();
430 
431 	/* Call into cpu_idle with preempt disabled */
432 	cpu_idle();
433 }
434 
435 /* Check for early params. */
436 static int __init do_early_param(char *param, char *val)
437 {
438 	struct obs_kernel_param *p;
439 
440 	for (p = __setup_start; p < __setup_end; p++) {
441 		if ((p->early && strcmp(param, p->str) == 0) ||
442 		    (strcmp(param, "console") == 0 &&
443 		     strcmp(p->str, "earlycon") == 0)
444 		) {
445 			if (p->setup_func(val) != 0)
446 				printk(KERN_WARNING
447 				       "Malformed early option '%s'\n", param);
448 		}
449 	}
450 	/* We accept everything at this stage. */
451 	return 0;
452 }
453 
454 void __init parse_early_options(char *cmdline)
455 {
456 	parse_args("early options", cmdline, NULL, 0, do_early_param);
457 }
458 
459 /* Arch code calls this early on, or if not, just before other parsing. */
460 void __init parse_early_param(void)
461 {
462 	static __initdata int done = 0;
463 	static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
464 
465 	if (done)
466 		return;
467 
468 	/* All fall through to do_early_param. */
469 	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
470 	parse_early_options(tmp_cmdline);
471 	done = 1;
472 }
473 
474 /*
475  *	Activate the first processor.
476  */
477 
478 static void __init boot_cpu_init(void)
479 {
480 	int cpu = smp_processor_id();
481 	/* Mark the boot cpu "present", "online" etc for SMP and UP case */
482 	set_cpu_online(cpu, true);
483 	set_cpu_active(cpu, true);
484 	set_cpu_present(cpu, true);
485 	set_cpu_possible(cpu, true);
486 }
487 
488 void __init __weak smp_setup_processor_id(void)
489 {
490 }
491 
492 void __init __weak thread_info_cache_init(void)
493 {
494 }
495 
496 /*
497  * Set up kernel memory allocators
498  */
499 static void __init mm_init(void)
500 {
501 	/*
502 	 * page_cgroup requires countinous pages as memmap
503 	 * and it's bigger than MAX_ORDER unless SPARSEMEM.
504 	 */
505 	page_cgroup_init_flatmem();
506 	mem_init();
507 	kmem_cache_init();
508 	pgtable_cache_init();
509 	vmalloc_init();
510 }
511 
512 asmlinkage void __init start_kernel(void)
513 {
514 	char * command_line;
515 	extern struct kernel_param __start___param[], __stop___param[];
516 
517 	smp_setup_processor_id();
518 
519 	/*
520 	 * Need to run as early as possible, to initialize the
521 	 * lockdep hash:
522 	 */
523 	lockdep_init();
524 	debug_objects_early_init();
525 
526 	/*
527 	 * Set up the the initial canary ASAP:
528 	 */
529 	boot_init_stack_canary();
530 
531 	cgroup_init_early();
532 
533 	local_irq_disable();
534 	early_boot_irqs_off();
535 	early_init_irq_lock_class();
536 
537 /*
538  * Interrupts are still disabled. Do necessary setups, then
539  * enable them
540  */
541 	lock_kernel();
542 	tick_init();
543 	boot_cpu_init();
544 	page_address_init();
545 	printk(KERN_NOTICE "%s", linux_banner);
546 	setup_arch(&command_line);
547 	mm_init_owner(&init_mm, &init_task);
548 	setup_command_line(command_line);
549 	setup_nr_cpu_ids();
550 	setup_per_cpu_areas();
551 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
552 
553 	build_all_zonelists();
554 	page_alloc_init();
555 
556 	printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
557 	parse_early_param();
558 	parse_args("Booting kernel", static_command_line, __start___param,
559 		   __stop___param - __start___param,
560 		   &unknown_bootoption);
561 	/*
562 	 * These use large bootmem allocations and must precede
563 	 * kmem_cache_init()
564 	 */
565 	pidhash_init();
566 	vfs_caches_init_early();
567 	sort_main_extable();
568 	trap_init();
569 	mm_init();
570 	/*
571 	 * Set up the scheduler prior starting any interrupts (such as the
572 	 * timer interrupt). Full topology setup happens at smp_init()
573 	 * time - but meanwhile we still have a functioning scheduler.
574 	 */
575 	sched_init();
576 	/*
577 	 * Disable preemption - early bootup scheduling is extremely
578 	 * fragile until we cpu_idle() for the first time.
579 	 */
580 	preempt_disable();
581 	if (!irqs_disabled()) {
582 		printk(KERN_WARNING "start_kernel(): bug: interrupts were "
583 				"enabled *very* early, fixing it\n");
584 		local_irq_disable();
585 	}
586 	rcu_init();
587 	/* init some links before init_ISA_irqs() */
588 	early_irq_init();
589 	init_IRQ();
590 	prio_tree_init();
591 	init_timers();
592 	hrtimers_init();
593 	softirq_init();
594 	timekeeping_init();
595 	time_init();
596 	profile_init();
597 	if (!irqs_disabled())
598 		printk(KERN_CRIT "start_kernel(): bug: interrupts were "
599 				 "enabled early\n");
600 	early_boot_irqs_on();
601 	local_irq_enable();
602 
603 	/* Interrupts are enabled now so all GFP allocations are safe. */
604 	set_gfp_allowed_mask(__GFP_BITS_MASK);
605 
606 	kmem_cache_init_late();
607 
608 	/*
609 	 * HACK ALERT! This is early. We're enabling the console before
610 	 * we've done PCI setups etc, and console_init() must be aware of
611 	 * this. But we do want output early, in case something goes wrong.
612 	 */
613 	console_init();
614 	if (panic_later)
615 		panic(panic_later, panic_param);
616 
617 	lockdep_info();
618 
619 	/*
620 	 * Need to run this when irqs are enabled, because it wants
621 	 * to self-test [hard/soft]-irqs on/off lock inversion bugs
622 	 * too:
623 	 */
624 	locking_selftest();
625 
626 #ifdef CONFIG_BLK_DEV_INITRD
627 	if (initrd_start && !initrd_below_start_ok &&
628 	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
629 		printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
630 		    "disabling it.\n",
631 		    page_to_pfn(virt_to_page((void *)initrd_start)),
632 		    min_low_pfn);
633 		initrd_start = 0;
634 	}
635 #endif
636 	page_cgroup_init();
637 	enable_debug_pagealloc();
638 	kmemtrace_init();
639 	kmemleak_init();
640 	debug_objects_mem_init();
641 	idr_init_cache();
642 	setup_per_cpu_pageset();
643 	numa_policy_init();
644 	if (late_time_init)
645 		late_time_init();
646 	sched_clock_init();
647 	calibrate_delay();
648 	pidmap_init();
649 	anon_vma_init();
650 #ifdef CONFIG_X86
651 	if (efi_enabled)
652 		efi_enter_virtual_mode();
653 #endif
654 	thread_info_cache_init();
655 	cred_init();
656 	fork_init(totalram_pages);
657 	proc_caches_init();
658 	buffer_init();
659 	key_init();
660 	radix_tree_init();
661 	security_init();
662 	vfs_caches_init(totalram_pages);
663 	signals_init();
664 	/* rootfs populating might need page-writeback */
665 	page_writeback_init();
666 #ifdef CONFIG_PROC_FS
667 	proc_root_init();
668 #endif
669 	cgroup_init();
670 	cpuset_init();
671 	taskstats_init_early();
672 	delayacct_init();
673 
674 	check_bugs();
675 
676 	acpi_early_init(); /* before LAPIC and SMP init */
677 	sfi_init_late();
678 
679 	ftrace_init();
680 
681 	/* Do the rest non-__init'ed, we're now alive */
682 	rest_init();
683 }
684 
685 /* Call all constructor functions linked into the kernel. */
686 static void __init do_ctors(void)
687 {
688 #ifdef CONFIG_CONSTRUCTORS
689 	ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
690 
691 	for (; fn < (ctor_fn_t *) __ctors_end; fn++)
692 		(*fn)();
693 #endif
694 }
695 
696 int initcall_debug;
697 core_param(initcall_debug, initcall_debug, bool, 0644);
698 
699 static char msgbuf[64];
700 static struct boot_trace_call call;
701 static struct boot_trace_ret ret;
702 
703 int do_one_initcall(initcall_t fn)
704 {
705 	int count = preempt_count();
706 	ktime_t calltime, delta, rettime;
707 
708 	if (initcall_debug) {
709 		call.caller = task_pid_nr(current);
710 		printk("calling  %pF @ %i\n", fn, call.caller);
711 		calltime = ktime_get();
712 		trace_boot_call(&call, fn);
713 		enable_boot_trace();
714 	}
715 
716 	ret.result = fn();
717 
718 	if (initcall_debug) {
719 		disable_boot_trace();
720 		rettime = ktime_get();
721 		delta = ktime_sub(rettime, calltime);
722 		ret.duration = (unsigned long long) ktime_to_ns(delta) >> 10;
723 		trace_boot_ret(&ret, fn);
724 		printk("initcall %pF returned %d after %Ld usecs\n", fn,
725 			ret.result, ret.duration);
726 	}
727 
728 	msgbuf[0] = 0;
729 
730 	if (ret.result && ret.result != -ENODEV && initcall_debug)
731 		sprintf(msgbuf, "error code %d ", ret.result);
732 
733 	if (preempt_count() != count) {
734 		strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
735 		preempt_count() = count;
736 	}
737 	if (irqs_disabled()) {
738 		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
739 		local_irq_enable();
740 	}
741 	if (msgbuf[0]) {
742 		printk("initcall %pF returned with %s\n", fn, msgbuf);
743 	}
744 
745 	return ret.result;
746 }
747 
748 
749 extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
750 
751 static void __init do_initcalls(void)
752 {
753 	initcall_t *fn;
754 
755 	for (fn = __early_initcall_end; fn < __initcall_end; fn++)
756 		do_one_initcall(*fn);
757 
758 	/* Make sure there is no pending stuff from the initcall sequence */
759 	flush_scheduled_work();
760 }
761 
762 /*
763  * Ok, the machine is now initialized. None of the devices
764  * have been touched yet, but the CPU subsystem is up and
765  * running, and memory and process management works.
766  *
767  * Now we can finally start doing some real work..
768  */
769 static void __init do_basic_setup(void)
770 {
771 	init_workqueues();
772 	cpuset_init_smp();
773 	usermodehelper_init();
774 	init_tmpfs();
775 	driver_init();
776 	init_irq_proc();
777 	do_ctors();
778 	do_initcalls();
779 }
780 
781 static void __init do_pre_smp_initcalls(void)
782 {
783 	initcall_t *fn;
784 
785 	for (fn = __initcall_start; fn < __early_initcall_end; fn++)
786 		do_one_initcall(*fn);
787 }
788 
789 static void run_init_process(char *init_filename)
790 {
791 	argv_init[0] = init_filename;
792 	kernel_execve(init_filename, argv_init, envp_init);
793 }
794 
795 /* This is a non __init function. Force it to be noinline otherwise gcc
796  * makes it inline to init() and it becomes part of init.text section
797  */
798 static noinline int init_post(void)
799 	__releases(kernel_lock)
800 {
801 	/* need to finish all async __init code before freeing the memory */
802 	async_synchronize_full();
803 	free_initmem();
804 	unlock_kernel();
805 	mark_rodata_ro();
806 	system_state = SYSTEM_RUNNING;
807 	numa_default_policy();
808 
809 	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
810 		printk(KERN_WARNING "Warning: unable to open an initial console.\n");
811 
812 	(void) sys_dup(0);
813 	(void) sys_dup(0);
814 
815 	current->signal->flags |= SIGNAL_UNKILLABLE;
816 
817 	if (ramdisk_execute_command) {
818 		run_init_process(ramdisk_execute_command);
819 		printk(KERN_WARNING "Failed to execute %s\n",
820 				ramdisk_execute_command);
821 	}
822 
823 	/*
824 	 * We try each of these until one succeeds.
825 	 *
826 	 * The Bourne shell can be used instead of init if we are
827 	 * trying to recover a really broken machine.
828 	 */
829 	if (execute_command) {
830 		run_init_process(execute_command);
831 		printk(KERN_WARNING "Failed to execute %s.  Attempting "
832 					"defaults...\n", execute_command);
833 	}
834 	run_init_process("/sbin/init");
835 	run_init_process("/etc/init");
836 	run_init_process("/bin/init");
837 	run_init_process("/bin/sh");
838 
839 	panic("No init found.  Try passing init= option to kernel.");
840 }
841 
842 static int __init kernel_init(void * unused)
843 {
844 	lock_kernel();
845 
846 	/*
847 	 * init can allocate pages on any node
848 	 */
849 	set_mems_allowed(node_possible_map);
850 	/*
851 	 * init can run on any cpu.
852 	 */
853 	set_cpus_allowed_ptr(current, cpu_all_mask);
854 	/*
855 	 * Tell the world that we're going to be the grim
856 	 * reaper of innocent orphaned children.
857 	 *
858 	 * We don't want people to have to make incorrect
859 	 * assumptions about where in the task array this
860 	 * can be found.
861 	 */
862 	init_pid_ns.child_reaper = current;
863 
864 	cad_pid = task_pid(current);
865 
866 	smp_prepare_cpus(setup_max_cpus);
867 
868 	do_pre_smp_initcalls();
869 	start_boot_trace();
870 
871 	smp_init();
872 	sched_init_smp();
873 
874 	do_basic_setup();
875 
876 	/*
877 	 * check if there is an early userspace init.  If yes, let it do all
878 	 * the work
879 	 */
880 
881 	if (!ramdisk_execute_command)
882 		ramdisk_execute_command = "/init";
883 
884 	if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
885 		ramdisk_execute_command = NULL;
886 		prepare_namespace();
887 	}
888 
889 	/*
890 	 * Ok, we have completed the initial bootup, and
891 	 * we're essentially up and running. Get rid of the
892 	 * initmem segments and start the user-mode stuff..
893 	 */
894 
895 	init_post();
896 	return 0;
897 }
898