xref: /openbmc/linux/init/main.c (revision b04b4f78)
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/utsname.h>
22 #include <linux/ioport.h>
23 #include <linux/init.h>
24 #include <linux/smp_lock.h>
25 #include <linux/initrd.h>
26 #include <linux/bootmem.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/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/ftrace.h>
66 #include <linux/async.h>
67 #include <trace/boot.h>
68 
69 #include <asm/io.h>
70 #include <asm/bugs.h>
71 #include <asm/setup.h>
72 #include <asm/sections.h>
73 #include <asm/cacheflush.h>
74 #include <trace/kmemtrace.h>
75 
76 #ifdef CONFIG_X86_LOCAL_APIC
77 #include <asm/smp.h>
78 #endif
79 
80 static int kernel_init(void *);
81 
82 extern void init_IRQ(void);
83 extern void fork_init(unsigned long);
84 extern void mca_init(void);
85 extern void sbus_init(void);
86 extern void prio_tree_init(void);
87 extern void radix_tree_init(void);
88 extern void free_initmem(void);
89 #ifdef	CONFIG_ACPI
90 extern void acpi_early_init(void);
91 #else
92 static inline void acpi_early_init(void) { }
93 #endif
94 #ifndef CONFIG_DEBUG_RODATA
95 static inline void mark_rodata_ro(void) { }
96 #endif
97 
98 #ifdef CONFIG_TC
99 extern void tc_init(void);
100 #endif
101 
102 enum system_states system_state __read_mostly;
103 EXPORT_SYMBOL(system_state);
104 
105 /*
106  * Boot command-line arguments
107  */
108 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
109 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
110 
111 extern void time_init(void);
112 /* Default late time init is NULL. archs can override this later. */
113 void (*__initdata late_time_init)(void);
114 extern void softirq_init(void);
115 
116 /* Untouched command line saved by arch-specific code. */
117 char __initdata boot_command_line[COMMAND_LINE_SIZE];
118 /* Untouched saved command line (eg. for /proc) */
119 char *saved_command_line;
120 /* Command line for parameter parsing */
121 static char *static_command_line;
122 
123 static char *execute_command;
124 static char *ramdisk_execute_command;
125 
126 #ifdef CONFIG_SMP
127 /* Setup configured maximum number of CPUs to activate */
128 unsigned int __initdata setup_max_cpus = NR_CPUS;
129 
130 /*
131  * Setup routine for controlling SMP activation
132  *
133  * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
134  * activation entirely (the MPS table probe still happens, though).
135  *
136  * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
137  * greater than 0, limits the maximum number of CPUs activated in
138  * SMP mode to <NUM>.
139  */
140 
141 void __weak arch_disable_smp_support(void) { }
142 
143 static int __init nosmp(char *str)
144 {
145 	setup_max_cpus = 0;
146 	arch_disable_smp_support();
147 
148 	return 0;
149 }
150 
151 early_param("nosmp", nosmp);
152 
153 static int __init maxcpus(char *str)
154 {
155 	get_option(&str, &setup_max_cpus);
156 	if (setup_max_cpus == 0)
157 		arch_disable_smp_support();
158 
159 	return 0;
160 }
161 
162 early_param("maxcpus", maxcpus);
163 #else
164 const unsigned int setup_max_cpus = NR_CPUS;
165 #endif
166 
167 /*
168  * If set, this is an indication to the drivers that reset the underlying
169  * device before going ahead with the initialization otherwise driver might
170  * rely on the BIOS and skip the reset operation.
171  *
172  * This is useful if kernel is booting in an unreliable environment.
173  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
174  * skipped and devices will be in unknown state.
175  */
176 unsigned int reset_devices;
177 EXPORT_SYMBOL(reset_devices);
178 
179 static int __init set_reset_devices(char *str)
180 {
181 	reset_devices = 1;
182 	return 1;
183 }
184 
185 __setup("reset_devices", set_reset_devices);
186 
187 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
188 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
189 static const char *panic_later, *panic_param;
190 
191 extern struct obs_kernel_param __setup_start[], __setup_end[];
192 
193 static int __init obsolete_checksetup(char *line)
194 {
195 	struct obs_kernel_param *p;
196 	int had_early_param = 0;
197 
198 	p = __setup_start;
199 	do {
200 		int n = strlen(p->str);
201 		if (!strncmp(line, p->str, n)) {
202 			if (p->early) {
203 				/* Already done in parse_early_param?
204 				 * (Needs exact match on param part).
205 				 * Keep iterating, as we can have early
206 				 * params and __setups of same names 8( */
207 				if (line[n] == '\0' || line[n] == '=')
208 					had_early_param = 1;
209 			} else if (!p->setup_func) {
210 				printk(KERN_WARNING "Parameter %s is obsolete,"
211 				       " ignored\n", p->str);
212 				return 1;
213 			} else if (p->setup_func(line + n))
214 				return 1;
215 		}
216 		p++;
217 	} while (p < __setup_end);
218 
219 	return had_early_param;
220 }
221 
222 /*
223  * This should be approx 2 Bo*oMips to start (note initial shift), and will
224  * still work even if initially too large, it will just take slightly longer
225  */
226 unsigned long loops_per_jiffy = (1<<12);
227 
228 EXPORT_SYMBOL(loops_per_jiffy);
229 
230 static int __init debug_kernel(char *str)
231 {
232 	console_loglevel = 10;
233 	return 0;
234 }
235 
236 static int __init quiet_kernel(char *str)
237 {
238 	console_loglevel = 4;
239 	return 0;
240 }
241 
242 early_param("debug", debug_kernel);
243 early_param("quiet", quiet_kernel);
244 
245 static int __init loglevel(char *str)
246 {
247 	get_option(&str, &console_loglevel);
248 	return 0;
249 }
250 
251 early_param("loglevel", loglevel);
252 
253 /*
254  * Unknown boot options get handed to init, unless they look like
255  * failed parameters
256  */
257 static int __init unknown_bootoption(char *param, char *val)
258 {
259 	/* Change NUL term back to "=", to make "param" the whole string. */
260 	if (val) {
261 		/* param=val or param="val"? */
262 		if (val == param+strlen(param)+1)
263 			val[-1] = '=';
264 		else if (val == param+strlen(param)+2) {
265 			val[-2] = '=';
266 			memmove(val-1, val, strlen(val)+1);
267 			val--;
268 		} else
269 			BUG();
270 	}
271 
272 	/* Handle obsolete-style parameters */
273 	if (obsolete_checksetup(param))
274 		return 0;
275 
276 	/*
277 	 * Preemptive maintenance for "why didn't my misspelled command
278 	 * line work?"
279 	 */
280 	if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
281 		printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
282 		return 0;
283 	}
284 
285 	if (panic_later)
286 		return 0;
287 
288 	if (val) {
289 		/* Environment option */
290 		unsigned int i;
291 		for (i = 0; envp_init[i]; i++) {
292 			if (i == MAX_INIT_ENVS) {
293 				panic_later = "Too many boot env vars at `%s'";
294 				panic_param = param;
295 			}
296 			if (!strncmp(param, envp_init[i], val - param))
297 				break;
298 		}
299 		envp_init[i] = param;
300 	} else {
301 		/* Command line option */
302 		unsigned int i;
303 		for (i = 0; argv_init[i]; i++) {
304 			if (i == MAX_INIT_ARGS) {
305 				panic_later = "Too many boot init vars at `%s'";
306 				panic_param = param;
307 			}
308 		}
309 		argv_init[i] = param;
310 	}
311 	return 0;
312 }
313 
314 #ifdef CONFIG_DEBUG_PAGEALLOC
315 int __read_mostly debug_pagealloc_enabled = 0;
316 #endif
317 
318 static int __init init_setup(char *str)
319 {
320 	unsigned int i;
321 
322 	execute_command = str;
323 	/*
324 	 * In case LILO is going to boot us with default command line,
325 	 * it prepends "auto" before the whole cmdline which makes
326 	 * the shell think it should execute a script with such name.
327 	 * So we ignore all arguments entered _before_ init=... [MJ]
328 	 */
329 	for (i = 1; i < MAX_INIT_ARGS; i++)
330 		argv_init[i] = NULL;
331 	return 1;
332 }
333 __setup("init=", init_setup);
334 
335 static int __init rdinit_setup(char *str)
336 {
337 	unsigned int i;
338 
339 	ramdisk_execute_command = str;
340 	/* See "auto" comment in init_setup */
341 	for (i = 1; i < MAX_INIT_ARGS; i++)
342 		argv_init[i] = NULL;
343 	return 1;
344 }
345 __setup("rdinit=", rdinit_setup);
346 
347 #ifndef CONFIG_SMP
348 
349 #ifdef CONFIG_X86_LOCAL_APIC
350 static void __init smp_init(void)
351 {
352 	APIC_init_uniprocessor();
353 }
354 #else
355 #define smp_init()	do { } while (0)
356 #endif
357 
358 static inline void setup_per_cpu_areas(void) { }
359 static inline void setup_nr_cpu_ids(void) { }
360 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
361 
362 #else
363 
364 #if NR_CPUS > BITS_PER_LONG
365 cpumask_t cpu_mask_all __read_mostly = CPU_MASK_ALL;
366 EXPORT_SYMBOL(cpu_mask_all);
367 #endif
368 
369 /* Setup number of possible processor ids */
370 int nr_cpu_ids __read_mostly = NR_CPUS;
371 EXPORT_SYMBOL(nr_cpu_ids);
372 
373 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
374 static void __init setup_nr_cpu_ids(void)
375 {
376 	nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
377 }
378 
379 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
380 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
381 
382 EXPORT_SYMBOL(__per_cpu_offset);
383 
384 static void __init setup_per_cpu_areas(void)
385 {
386 	unsigned long size, i;
387 	char *ptr;
388 	unsigned long nr_possible_cpus = num_possible_cpus();
389 
390 	/* Copy section for each CPU (we discard the original) */
391 	size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
392 	ptr = alloc_bootmem_pages(size * nr_possible_cpus);
393 
394 	for_each_possible_cpu(i) {
395 		__per_cpu_offset[i] = ptr - __per_cpu_start;
396 		memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
397 		ptr += size;
398 	}
399 }
400 #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
401 
402 /* Called by boot processor to activate the rest. */
403 static void __init smp_init(void)
404 {
405 	unsigned int cpu;
406 
407 	/*
408 	 * Set up the current CPU as possible to migrate to.
409 	 * The other ones will be done by cpu_up/cpu_down()
410 	 */
411 	set_cpu_active(smp_processor_id(), true);
412 
413 	/* FIXME: This should be done in userspace --RR */
414 	for_each_present_cpu(cpu) {
415 		if (num_online_cpus() >= setup_max_cpus)
416 			break;
417 		if (!cpu_online(cpu))
418 			cpu_up(cpu);
419 	}
420 
421 	/* Any cleanup work */
422 	printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
423 	smp_cpus_done(setup_max_cpus);
424 }
425 
426 #endif
427 
428 /*
429  * We need to store the untouched command line for future reference.
430  * We also need to store the touched command line since the parameter
431  * parsing is performed in place, and we should allow a component to
432  * store reference of name/value for future reference.
433  */
434 static void __init setup_command_line(char *command_line)
435 {
436 	saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
437 	static_command_line = alloc_bootmem(strlen (command_line)+1);
438 	strcpy (saved_command_line, boot_command_line);
439 	strcpy (static_command_line, command_line);
440 }
441 
442 /*
443  * We need to finalize in a non-__init function or else race conditions
444  * between the root thread and the init thread may cause start_kernel to
445  * be reaped by free_initmem before the root thread has proceeded to
446  * cpu_idle.
447  *
448  * gcc-3.4 accidentally inlines this function, so use noinline.
449  */
450 
451 static noinline void __init_refok rest_init(void)
452 	__releases(kernel_lock)
453 {
454 	int pid;
455 
456 	kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
457 	numa_default_policy();
458 	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
459 	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
460 	unlock_kernel();
461 
462 	/*
463 	 * The boot idle thread must execute schedule()
464 	 * at least once to get things moving:
465 	 */
466 	init_idle_bootup_task(current);
467 	rcu_scheduler_starting();
468 	preempt_enable_no_resched();
469 	schedule();
470 	preempt_disable();
471 
472 	/* Call into cpu_idle with preempt disabled */
473 	cpu_idle();
474 }
475 
476 /* Check for early params. */
477 static int __init do_early_param(char *param, char *val)
478 {
479 	struct obs_kernel_param *p;
480 
481 	for (p = __setup_start; p < __setup_end; p++) {
482 		if ((p->early && strcmp(param, p->str) == 0) ||
483 		    (strcmp(param, "console") == 0 &&
484 		     strcmp(p->str, "earlycon") == 0)
485 		) {
486 			if (p->setup_func(val) != 0)
487 				printk(KERN_WARNING
488 				       "Malformed early option '%s'\n", param);
489 		}
490 	}
491 	/* We accept everything at this stage. */
492 	return 0;
493 }
494 
495 void __init parse_early_options(char *cmdline)
496 {
497 	parse_args("early options", cmdline, NULL, 0, do_early_param);
498 }
499 
500 /* Arch code calls this early on, or if not, just before other parsing. */
501 void __init parse_early_param(void)
502 {
503 	static __initdata int done = 0;
504 	static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
505 
506 	if (done)
507 		return;
508 
509 	/* All fall through to do_early_param. */
510 	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
511 	parse_early_options(tmp_cmdline);
512 	done = 1;
513 }
514 
515 /*
516  *	Activate the first processor.
517  */
518 
519 static void __init boot_cpu_init(void)
520 {
521 	int cpu = smp_processor_id();
522 	/* Mark the boot cpu "present", "online" etc for SMP and UP case */
523 	set_cpu_online(cpu, true);
524 	set_cpu_present(cpu, true);
525 	set_cpu_possible(cpu, true);
526 }
527 
528 void __init __weak smp_setup_processor_id(void)
529 {
530 }
531 
532 void __init __weak thread_info_cache_init(void)
533 {
534 }
535 
536 asmlinkage void __init start_kernel(void)
537 {
538 	char * command_line;
539 	extern struct kernel_param __start___param[], __stop___param[];
540 
541 	smp_setup_processor_id();
542 
543 	/*
544 	 * Need to run as early as possible, to initialize the
545 	 * lockdep hash:
546 	 */
547 	lockdep_init();
548 	debug_objects_early_init();
549 
550 	/*
551 	 * Set up the the initial canary ASAP:
552 	 */
553 	boot_init_stack_canary();
554 
555 	cgroup_init_early();
556 
557 	local_irq_disable();
558 	early_boot_irqs_off();
559 	early_init_irq_lock_class();
560 
561 /*
562  * Interrupts are still disabled. Do necessary setups, then
563  * enable them
564  */
565 	lock_kernel();
566 	tick_init();
567 	boot_cpu_init();
568 	page_address_init();
569 	printk(KERN_NOTICE);
570 	printk(linux_banner);
571 	setup_arch(&command_line);
572 	mm_init_owner(&init_mm, &init_task);
573 	setup_command_line(command_line);
574 	setup_per_cpu_areas();
575 	setup_nr_cpu_ids();
576 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
577 
578 	/*
579 	 * Set up the scheduler prior starting any interrupts (such as the
580 	 * timer interrupt). Full topology setup happens at smp_init()
581 	 * time - but meanwhile we still have a functioning scheduler.
582 	 */
583 	sched_init();
584 	/*
585 	 * Disable preemption - early bootup scheduling is extremely
586 	 * fragile until we cpu_idle() for the first time.
587 	 */
588 	preempt_disable();
589 	build_all_zonelists();
590 	page_alloc_init();
591 	printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
592 	parse_early_param();
593 	parse_args("Booting kernel", static_command_line, __start___param,
594 		   __stop___param - __start___param,
595 		   &unknown_bootoption);
596 	if (!irqs_disabled()) {
597 		printk(KERN_WARNING "start_kernel(): bug: interrupts were "
598 				"enabled *very* early, fixing it\n");
599 		local_irq_disable();
600 	}
601 	sort_main_extable();
602 	trap_init();
603 	rcu_init();
604 	/* init some links before init_ISA_irqs() */
605 	early_irq_init();
606 	init_IRQ();
607 	pidhash_init();
608 	init_timers();
609 	hrtimers_init();
610 	softirq_init();
611 	timekeeping_init();
612 	time_init();
613 	sched_clock_init();
614 	profile_init();
615 	if (!irqs_disabled())
616 		printk(KERN_CRIT "start_kernel(): bug: interrupts were "
617 				 "enabled early\n");
618 	early_boot_irqs_on();
619 	local_irq_enable();
620 
621 	/*
622 	 * HACK ALERT! This is early. We're enabling the console before
623 	 * we've done PCI setups etc, and console_init() must be aware of
624 	 * this. But we do want output early, in case something goes wrong.
625 	 */
626 	console_init();
627 	if (panic_later)
628 		panic(panic_later, panic_param);
629 
630 	lockdep_info();
631 
632 	/*
633 	 * Need to run this when irqs are enabled, because it wants
634 	 * to self-test [hard/soft]-irqs on/off lock inversion bugs
635 	 * too:
636 	 */
637 	locking_selftest();
638 
639 #ifdef CONFIG_BLK_DEV_INITRD
640 	if (initrd_start && !initrd_below_start_ok &&
641 	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
642 		printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
643 		    "disabling it.\n",
644 		    page_to_pfn(virt_to_page((void *)initrd_start)),
645 		    min_low_pfn);
646 		initrd_start = 0;
647 	}
648 #endif
649 	vmalloc_init();
650 	vfs_caches_init_early();
651 	cpuset_init_early();
652 	page_cgroup_init();
653 	mem_init();
654 	enable_debug_pagealloc();
655 	cpu_hotplug_init();
656 	kmem_cache_init();
657 	kmemtrace_init();
658 	debug_objects_mem_init();
659 	idr_init_cache();
660 	setup_per_cpu_pageset();
661 	numa_policy_init();
662 	if (late_time_init)
663 		late_time_init();
664 	calibrate_delay();
665 	pidmap_init();
666 	pgtable_cache_init();
667 	prio_tree_init();
668 	anon_vma_init();
669 #ifdef CONFIG_X86
670 	if (efi_enabled)
671 		efi_enter_virtual_mode();
672 #endif
673 	thread_info_cache_init();
674 	cred_init();
675 	fork_init(num_physpages);
676 	proc_caches_init();
677 	buffer_init();
678 	key_init();
679 	security_init();
680 	vfs_caches_init(num_physpages);
681 	radix_tree_init();
682 	signals_init();
683 	/* rootfs populating might need page-writeback */
684 	page_writeback_init();
685 #ifdef CONFIG_PROC_FS
686 	proc_root_init();
687 #endif
688 	cgroup_init();
689 	cpuset_init();
690 	taskstats_init_early();
691 	delayacct_init();
692 
693 	check_bugs();
694 
695 	acpi_early_init(); /* before LAPIC and SMP init */
696 
697 	ftrace_init();
698 
699 	/* Do the rest non-__init'ed, we're now alive */
700 	rest_init();
701 }
702 
703 int initcall_debug;
704 core_param(initcall_debug, initcall_debug, bool, 0644);
705 
706 int do_one_initcall(initcall_t fn)
707 {
708 	int count = preempt_count();
709 	ktime_t calltime, delta, rettime;
710 	char msgbuf[64];
711 	struct boot_trace_call call;
712 	struct boot_trace_ret ret;
713 
714 	if (initcall_debug) {
715 		call.caller = task_pid_nr(current);
716 		printk("calling  %pF @ %i\n", fn, call.caller);
717 		calltime = ktime_get();
718 		trace_boot_call(&call, fn);
719 		enable_boot_trace();
720 	}
721 
722 	ret.result = fn();
723 
724 	if (initcall_debug) {
725 		disable_boot_trace();
726 		rettime = ktime_get();
727 		delta = ktime_sub(rettime, calltime);
728 		ret.duration = (unsigned long long) ktime_to_ns(delta) >> 10;
729 		trace_boot_ret(&ret, fn);
730 		printk("initcall %pF returned %d after %Ld usecs\n", fn,
731 			ret.result, ret.duration);
732 	}
733 
734 	msgbuf[0] = 0;
735 
736 	if (ret.result && ret.result != -ENODEV && initcall_debug)
737 		sprintf(msgbuf, "error code %d ", ret.result);
738 
739 	if (preempt_count() != count) {
740 		strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
741 		preempt_count() = count;
742 	}
743 	if (irqs_disabled()) {
744 		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
745 		local_irq_enable();
746 	}
747 	if (msgbuf[0]) {
748 		printk("initcall %pF returned with %s\n", fn, msgbuf);
749 	}
750 
751 	return ret.result;
752 }
753 
754 
755 extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
756 
757 static void __init do_initcalls(void)
758 {
759 	initcall_t *call;
760 
761 	for (call = __early_initcall_end; call < __initcall_end; call++)
762 		do_one_initcall(*call);
763 
764 	/* Make sure there is no pending stuff from the initcall sequence */
765 	flush_scheduled_work();
766 }
767 
768 /*
769  * Ok, the machine is now initialized. None of the devices
770  * have been touched yet, but the CPU subsystem is up and
771  * running, and memory and process management works.
772  *
773  * Now we can finally start doing some real work..
774  */
775 static void __init do_basic_setup(void)
776 {
777 	rcu_init_sched(); /* needed by module_init stage. */
778 	init_workqueues();
779 	cpuset_init_smp();
780 	usermodehelper_init();
781 	driver_init();
782 	init_irq_proc();
783 	do_initcalls();
784 }
785 
786 static void __init do_pre_smp_initcalls(void)
787 {
788 	initcall_t *call;
789 
790 	for (call = __initcall_start; call < __early_initcall_end; call++)
791 		do_one_initcall(*call);
792 }
793 
794 static void run_init_process(char *init_filename)
795 {
796 	argv_init[0] = init_filename;
797 	kernel_execve(init_filename, argv_init, envp_init);
798 }
799 
800 /* This is a non __init function. Force it to be noinline otherwise gcc
801  * makes it inline to init() and it becomes part of init.text section
802  */
803 static noinline int init_post(void)
804 	__releases(kernel_lock)
805 {
806 	/* need to finish all async __init code before freeing the memory */
807 	async_synchronize_full();
808 	free_initmem();
809 	unlock_kernel();
810 	mark_rodata_ro();
811 	system_state = SYSTEM_RUNNING;
812 	numa_default_policy();
813 
814 	if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
815 		printk(KERN_WARNING "Warning: unable to open an initial console.\n");
816 
817 	(void) sys_dup(0);
818 	(void) sys_dup(0);
819 
820 	current->signal->flags |= SIGNAL_UNKILLABLE;
821 
822 	if (ramdisk_execute_command) {
823 		run_init_process(ramdisk_execute_command);
824 		printk(KERN_WARNING "Failed to execute %s\n",
825 				ramdisk_execute_command);
826 	}
827 
828 	/*
829 	 * We try each of these until one succeeds.
830 	 *
831 	 * The Bourne shell can be used instead of init if we are
832 	 * trying to recover a really broken machine.
833 	 */
834 	if (execute_command) {
835 		run_init_process(execute_command);
836 		printk(KERN_WARNING "Failed to execute %s.  Attempting "
837 					"defaults...\n", execute_command);
838 	}
839 	run_init_process("/sbin/init");
840 	run_init_process("/etc/init");
841 	run_init_process("/bin/init");
842 	run_init_process("/bin/sh");
843 
844 	panic("No init found.  Try passing init= option to kernel.");
845 }
846 
847 static int __init kernel_init(void * unused)
848 {
849 	lock_kernel();
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