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/string.h>
18 #include <linux/ctype.h>
19 #include <linux/delay.h>
20 #include <linux/utsname.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/tty.h>
27 #include <linux/gfp.h>
28 #include <linux/percpu.h>
29 #include <linux/kmod.h>
30 #include <linux/vmalloc.h>
31 #include <linux/kernel_stat.h>
32 #include <linux/start_kernel.h>
33 #include <linux/security.h>
34 #include <linux/smp.h>
35 #include <linux/workqueue.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/pid_namespace.h>
59 #include <linux/device.h>
60 #include <linux/kthread.h>
61 #include <linux/sched.h>
62 #include <linux/signal.h>
63 #include <linux/idr.h>
64 #include <linux/ftrace.h>
65 #include <linux/async.h>
66 #include <trace/boot.h>
67
68 #include <asm/io.h>
69 #include <asm/bugs.h>
70 #include <asm/setup.h>
71 #include <asm/sections.h>
72 #include <asm/cacheflush.h>
73
74 #ifdef CONFIG_X86_LOCAL_APIC
75 #include <asm/smp.h>
76 #endif
77
78 static int kernel_init(void *);
79
80 extern void init_IRQ(void);
81 extern void fork_init(unsigned long);
82 extern void mca_init(void);
83 extern void sbus_init(void);
84 extern void prio_tree_init(void);
85 extern void radix_tree_init(void);
86 extern void free_initmem(void);
87 #ifdef CONFIG_ACPI
88 extern void acpi_early_init(void);
89 #else
acpi_early_init(void)90 static inline void acpi_early_init(void) { }
91 #endif
92 #ifndef CONFIG_DEBUG_RODATA
mark_rodata_ro(void)93 static inline void mark_rodata_ro(void) { }
94 #endif
95
96 #ifdef CONFIG_TC
97 extern void tc_init(void);
98 #endif
99
100 enum system_states system_state __read_mostly;
101 EXPORT_SYMBOL(system_state);
102
103 /*
104 * Boot command-line arguments
105 */
106 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
107 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
108
109 extern void time_init(void);
110 /* Default late time init is NULL. archs can override this later. */
111 void (*__initdata late_time_init)(void);
112 extern void softirq_init(void);
113
114 /* Untouched command line saved by arch-specific code. */
115 char __initdata boot_command_line[COMMAND_LINE_SIZE];
116 /* Untouched saved command line (eg. for /proc) */
117 char *saved_command_line;
118 /* Command line for parameter parsing */
119 static char *static_command_line;
120
121 static char *execute_command;
122 static char *ramdisk_execute_command;
123
124 #ifdef CONFIG_SMP
125 /* Setup configured maximum number of CPUs to activate */
126 unsigned int __initdata setup_max_cpus = NR_CPUS;
127
128 /*
129 * Setup routine for controlling SMP activation
130 *
131 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
132 * activation entirely (the MPS table probe still happens, though).
133 *
134 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
135 * greater than 0, limits the maximum number of CPUs activated in
136 * SMP mode to <NUM>.
137 */
138 #ifndef CONFIG_X86_IO_APIC
disable_ioapic_setup(void)139 static inline void disable_ioapic_setup(void) {};
140 #endif
141
nosmp(char * str)142 static int __init nosmp(char *str)
143 {
144 setup_max_cpus = 0;
145 disable_ioapic_setup();
146 return 0;
147 }
148
149 early_param("nosmp", nosmp);
150
maxcpus(char * str)151 static int __init maxcpus(char *str)
152 {
153 get_option(&str, &setup_max_cpus);
154 if (setup_max_cpus == 0)
155 disable_ioapic_setup();
156
157 return 0;
158 }
159
160 early_param("maxcpus", maxcpus);
161 #else
162 #define setup_max_cpus NR_CPUS
163 #endif
164
165 /*
166 * If set, this is an indication to the drivers that reset the underlying
167 * device before going ahead with the initialization otherwise driver might
168 * rely on the BIOS and skip the reset operation.
169 *
170 * This is useful if kernel is booting in an unreliable environment.
171 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
172 * skipped and devices will be in unknown state.
173 */
174 unsigned int reset_devices;
175 EXPORT_SYMBOL(reset_devices);
176
set_reset_devices(char * str)177 static int __init set_reset_devices(char *str)
178 {
179 reset_devices = 1;
180 return 1;
181 }
182
183 __setup("reset_devices", set_reset_devices);
184
185 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
186 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
187 static const char *panic_later, *panic_param;
188
189 extern struct obs_kernel_param __setup_start[], __setup_end[];
190
obsolete_checksetup(char * line)191 static int __init obsolete_checksetup(char *line)
192 {
193 struct obs_kernel_param *p;
194 int had_early_param = 0;
195
196 p = __setup_start;
197 do {
198 int n = strlen(p->str);
199 if (!strncmp(line, p->str, n)) {
200 if (p->early) {
201 /* Already done in parse_early_param?
202 * (Needs exact match on param part).
203 * Keep iterating, as we can have early
204 * params and __setups of same names 8( */
205 if (line[n] == '\0' || line[n] == '=')
206 had_early_param = 1;
207 } else if (!p->setup_func) {
208 printk(KERN_WARNING "Parameter %s is obsolete,"
209 " ignored\n", p->str);
210 return 1;
211 } else if (p->setup_func(line + n))
212 return 1;
213 }
214 p++;
215 } while (p < __setup_end);
216
217 return had_early_param;
218 }
219
220 /*
221 * This should be approx 2 Bo*oMips to start (note initial shift), and will
222 * still work even if initially too large, it will just take slightly longer
223 */
224 unsigned long loops_per_jiffy = (1<<12);
225
226 EXPORT_SYMBOL(loops_per_jiffy);
227
debug_kernel(char * str)228 static int __init debug_kernel(char *str)
229 {
230 console_loglevel = 10;
231 return 0;
232 }
233
quiet_kernel(char * str)234 static int __init quiet_kernel(char *str)
235 {
236 console_loglevel = 4;
237 return 0;
238 }
239
240 early_param("debug", debug_kernel);
241 early_param("quiet", quiet_kernel);
242
loglevel(char * str)243 static int __init loglevel(char *str)
244 {
245 get_option(&str, &console_loglevel);
246 return 0;
247 }
248
249 early_param("loglevel", loglevel);
250
251 /*
252 * Unknown boot options get handed to init, unless they look like
253 * failed parameters
254 */
unknown_bootoption(char * param,char * val)255 static int __init unknown_bootoption(char *param, char *val)
256 {
257 /* Change NUL term back to "=", to make "param" the whole string. */
258 if (val) {
259 /* param=val or param="val"? */
260 if (val == param+strlen(param)+1)
261 val[-1] = '=';
262 else if (val == param+strlen(param)+2) {
263 val[-2] = '=';
264 memmove(val-1, val, strlen(val)+1);
265 val--;
266 } else
267 BUG();
268 }
269
270 /* Handle obsolete-style parameters */
271 if (obsolete_checksetup(param))
272 return 0;
273
274 /*
275 * Preemptive maintenance for "why didn't my misspelled command
276 * line work?"
277 */
278 if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
279 printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
280 return 0;
281 }
282
283 if (panic_later)
284 return 0;
285
286 if (val) {
287 /* Environment option */
288 unsigned int i;
289 for (i = 0; envp_init[i]; i++) {
290 if (i == MAX_INIT_ENVS) {
291 panic_later = "Too many boot env vars at `%s'";
292 panic_param = param;
293 }
294 if (!strncmp(param, envp_init[i], val - param))
295 break;
296 }
297 envp_init[i] = param;
298 } else {
299 /* Command line option */
300 unsigned int i;
301 for (i = 0; argv_init[i]; i++) {
302 if (i == MAX_INIT_ARGS) {
303 panic_later = "Too many boot init vars at `%s'";
304 panic_param = param;
305 }
306 }
307 argv_init[i] = param;
308 }
309 return 0;
310 }
311
312 #ifdef CONFIG_DEBUG_PAGEALLOC
313 int __read_mostly debug_pagealloc_enabled = 0;
314 #endif
315
init_setup(char * str)316 static int __init init_setup(char *str)
317 {
318 unsigned int i;
319
320 execute_command = str;
321 /*
322 * In case LILO is going to boot us with default command line,
323 * it prepends "auto" before the whole cmdline which makes
324 * the shell think it should execute a script with such name.
325 * So we ignore all arguments entered _before_ init=... [MJ]
326 */
327 for (i = 1; i < MAX_INIT_ARGS; i++)
328 argv_init[i] = NULL;
329 return 1;
330 }
331 __setup("init=", init_setup);
332
rdinit_setup(char * str)333 static int __init rdinit_setup(char *str)
334 {
335 unsigned int i;
336
337 ramdisk_execute_command = str;
338 /* See "auto" comment in init_setup */
339 for (i = 1; i < MAX_INIT_ARGS; i++)
340 argv_init[i] = NULL;
341 return 1;
342 }
343 __setup("rdinit=", rdinit_setup);
344
345 #ifndef CONFIG_SMP
346
347 #ifdef CONFIG_X86_LOCAL_APIC
smp_init(void)348 static void __init smp_init(void)
349 {
350 APIC_init_uniprocessor();
351 }
352 #else
353 #define smp_init() do { } while (0)
354 #endif
355
setup_per_cpu_areas(void)356 static inline void setup_per_cpu_areas(void) { }
setup_nr_cpu_ids(void)357 static inline void setup_nr_cpu_ids(void) { }
smp_prepare_cpus(unsigned int maxcpus)358 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
359
360 #else
361
362 #if NR_CPUS > BITS_PER_LONG
363 cpumask_t cpu_mask_all __read_mostly = CPU_MASK_ALL;
364 EXPORT_SYMBOL(cpu_mask_all);
365 #endif
366
367 /* Setup number of possible processor ids */
368 int nr_cpu_ids __read_mostly = NR_CPUS;
369 EXPORT_SYMBOL(nr_cpu_ids);
370
371 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
setup_nr_cpu_ids(void)372 static void __init setup_nr_cpu_ids(void)
373 {
374 nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
375 }
376
377 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
378 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
379
380 EXPORT_SYMBOL(__per_cpu_offset);
381
setup_per_cpu_areas(void)382 static void __init setup_per_cpu_areas(void)
383 {
384 unsigned long size, i;
385 char *ptr;
386 unsigned long nr_possible_cpus = num_possible_cpus();
387
388 /* Copy section for each CPU (we discard the original) */
389 size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
390 ptr = alloc_bootmem_pages(size * nr_possible_cpus);
391
392 for_each_possible_cpu(i) {
393 __per_cpu_offset[i] = ptr - __per_cpu_start;
394 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
395 ptr += size;
396 }
397 }
398 #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
399
400 /* Called by boot processor to activate the rest. */
smp_init(void)401 static void __init smp_init(void)
402 {
403 unsigned int cpu;
404
405 /*
406 * Set up the current CPU as possible to migrate to.
407 * The other ones will be done by cpu_up/cpu_down()
408 */
409 cpu = smp_processor_id();
410 cpu_set(cpu, cpu_active_map);
411
412 /* FIXME: This should be done in userspace --RR */
413 for_each_present_cpu(cpu) {
414 if (num_online_cpus() >= setup_max_cpus)
415 break;
416 if (!cpu_online(cpu))
417 cpu_up(cpu);
418 }
419
420 /* Any cleanup work */
421 printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
422 smp_cpus_done(setup_max_cpus);
423 }
424
425 #endif
426
427 /*
428 * We need to store the untouched command line for future reference.
429 * We also need to store the touched command line since the parameter
430 * parsing is performed in place, and we should allow a component to
431 * store reference of name/value for future reference.
432 */
setup_command_line(char * command_line)433 static void __init setup_command_line(char *command_line)
434 {
435 saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
436 static_command_line = alloc_bootmem(strlen (command_line)+1);
437 strcpy (saved_command_line, boot_command_line);
438 strcpy (static_command_line, command_line);
439 }
440
441 /*
442 * We need to finalize in a non-__init function or else race conditions
443 * between the root thread and the init thread may cause start_kernel to
444 * be reaped by free_initmem before the root thread has proceeded to
445 * cpu_idle.
446 *
447 * gcc-3.4 accidentally inlines this function, so use noinline.
448 */
449
rest_init(void)450 static noinline void __init_refok rest_init(void)
451 __releases(kernel_lock)
452 {
453 int pid;
454
455 kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
456 numa_default_policy();
457 pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
458 kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
459 unlock_kernel();
460
461 /*
462 * The boot idle thread must execute schedule()
463 * at least once to get things moving:
464 */
465 init_idle_bootup_task(current);
466 rcu_scheduler_starting();
467 preempt_enable_no_resched();
468 schedule();
469 preempt_disable();
470
471 /* Call into cpu_idle with preempt disabled */
472 cpu_idle();
473 }
474
475 /* Check for early params. */
do_early_param(char * param,char * val)476 static int __init do_early_param(char *param, char *val)
477 {
478 struct obs_kernel_param *p;
479
480 for (p = __setup_start; p < __setup_end; p++) {
481 if ((p->early && strcmp(param, p->str) == 0) ||
482 (strcmp(param, "console") == 0 &&
483 strcmp(p->str, "earlycon") == 0)
484 ) {
485 if (p->setup_func(val) != 0)
486 printk(KERN_WARNING
487 "Malformed early option '%s'\n", param);
488 }
489 }
490 /* We accept everything at this stage. */
491 return 0;
492 }
493
494 /* Arch code calls this early on, or if not, just before other parsing. */
parse_early_param(void)495 void __init parse_early_param(void)
496 {
497 static __initdata int done = 0;
498 static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
499
500 if (done)
501 return;
502
503 /* All fall through to do_early_param. */
504 strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
505 parse_args("early options", tmp_cmdline, NULL, 0, do_early_param);
506 done = 1;
507 }
508
509 /*
510 * Activate the first processor.
511 */
512
boot_cpu_init(void)513 static void __init boot_cpu_init(void)
514 {
515 int cpu = smp_processor_id();
516 /* Mark the boot cpu "present", "online" etc for SMP and UP case */
517 set_cpu_online(cpu, true);
518 set_cpu_present(cpu, true);
519 set_cpu_possible(cpu, true);
520 }
521
smp_setup_processor_id(void)522 void __init __weak smp_setup_processor_id(void)
523 {
524 }
525
thread_info_cache_init(void)526 void __init __weak thread_info_cache_init(void)
527 {
528 }
529
start_kernel(void)530 asmlinkage void __init start_kernel(void)
531 {
532 char * command_line;
533 extern struct kernel_param __start___param[], __stop___param[];
534
535 smp_setup_processor_id();
536
537 /*
538 * Need to run as early as possible, to initialize the
539 * lockdep hash:
540 */
541 lockdep_init();
542 debug_objects_early_init();
543 cgroup_init_early();
544
545 local_irq_disable();
546 early_boot_irqs_off();
547 early_init_irq_lock_class();
548
549 /*
550 * Interrupts are still disabled. Do necessary setups, then
551 * enable them
552 */
553 lock_kernel();
554 tick_init();
555 boot_cpu_init();
556 page_address_init();
557 printk(KERN_NOTICE);
558 printk(linux_banner);
559 setup_arch(&command_line);
560 mm_init_owner(&init_mm, &init_task);
561 setup_command_line(command_line);
562 setup_per_cpu_areas();
563 setup_nr_cpu_ids();
564 smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
565
566 /*
567 * Set up the scheduler prior starting any interrupts (such as the
568 * timer interrupt). Full topology setup happens at smp_init()
569 * time - but meanwhile we still have a functioning scheduler.
570 */
571 sched_init();
572 /*
573 * Disable preemption - early bootup scheduling is extremely
574 * fragile until we cpu_idle() for the first time.
575 */
576 preempt_disable();
577 build_all_zonelists();
578 page_alloc_init();
579 printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
580 parse_early_param();
581 parse_args("Booting kernel", static_command_line, __start___param,
582 __stop___param - __start___param,
583 &unknown_bootoption);
584 if (!irqs_disabled()) {
585 printk(KERN_WARNING "start_kernel(): bug: interrupts were "
586 "enabled *very* early, fixing it\n");
587 local_irq_disable();
588 }
589 sort_main_extable();
590 trap_init();
591 rcu_init();
592 /* init some links before init_ISA_irqs() */
593 early_irq_init();
594 init_IRQ();
595 pidhash_init();
596 init_timers();
597 hrtimers_init();
598 softirq_init();
599 timekeeping_init();
600 time_init();
601 sched_clock_init();
602 profile_init();
603 if (!irqs_disabled())
604 printk(KERN_CRIT "start_kernel(): bug: interrupts were "
605 "enabled early\n");
606 early_boot_irqs_on();
607 local_irq_enable();
608
609 /*
610 * HACK ALERT! This is early. We're enabling the console before
611 * we've done PCI setups etc, and console_init() must be aware of
612 * this. But we do want output early, in case something goes wrong.
613 */
614 console_init();
615 if (panic_later)
616 panic(panic_later, panic_param);
617
618 lockdep_info();
619
620 /*
621 * Need to run this when irqs are enabled, because it wants
622 * to self-test [hard/soft]-irqs on/off lock inversion bugs
623 * too:
624 */
625 locking_selftest();
626
627 #ifdef CONFIG_BLK_DEV_INITRD
628 if (initrd_start && !initrd_below_start_ok &&
629 page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
630 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
631 "disabling it.\n",
632 page_to_pfn(virt_to_page((void *)initrd_start)),
633 min_low_pfn);
634 initrd_start = 0;
635 }
636 #endif
637 vmalloc_init();
638 vfs_caches_init_early();
639 cpuset_init_early();
640 page_cgroup_init();
641 mem_init();
642 enable_debug_pagealloc();
643 cpu_hotplug_init();
644 kmem_cache_init();
645 debug_objects_mem_init();
646 idr_init_cache();
647 setup_per_cpu_pageset();
648 numa_policy_init();
649 if (late_time_init)
650 late_time_init();
651 calibrate_delay();
652 pidmap_init();
653 pgtable_cache_init();
654 prio_tree_init();
655 anon_vma_init();
656 #ifdef CONFIG_X86
657 if (efi_enabled)
658 efi_enter_virtual_mode();
659 #endif
660 thread_info_cache_init();
661 cred_init();
662 fork_init(num_physpages);
663 proc_caches_init();
664 buffer_init();
665 key_init();
666 security_init();
667 vfs_caches_init(num_physpages);
668 radix_tree_init();
669 signals_init();
670 /* rootfs populating might need page-writeback */
671 page_writeback_init();
672 #ifdef CONFIG_PROC_FS
673 proc_root_init();
674 #endif
675 cgroup_init();
676 cpuset_init();
677 taskstats_init_early();
678 delayacct_init();
679
680 check_bugs();
681
682 acpi_early_init(); /* before LAPIC and SMP init */
683
684 ftrace_init();
685
686 /* Do the rest non-__init'ed, we're now alive */
687 rest_init();
688 }
689
690 int initcall_debug;
691 core_param(initcall_debug, initcall_debug, bool, 0644);
692
do_one_initcall(initcall_t fn)693 int do_one_initcall(initcall_t fn)
694 {
695 int count = preempt_count();
696 ktime_t calltime, delta, rettime;
697 char msgbuf[64];
698 struct boot_trace_call call;
699 struct boot_trace_ret ret;
700
701 if (initcall_debug) {
702 call.caller = task_pid_nr(current);
703 printk("calling %pF @ %i\n", fn, call.caller);
704 calltime = ktime_get();
705 trace_boot_call(&call, fn);
706 enable_boot_trace();
707 }
708
709 ret.result = fn();
710
711 if (initcall_debug) {
712 disable_boot_trace();
713 rettime = ktime_get();
714 delta = ktime_sub(rettime, calltime);
715 ret.duration = (unsigned long long) ktime_to_ns(delta) >> 10;
716 trace_boot_ret(&ret, fn);
717 printk("initcall %pF returned %d after %Ld usecs\n", fn,
718 ret.result, ret.duration);
719 }
720
721 msgbuf[0] = 0;
722
723 if (ret.result && ret.result != -ENODEV && initcall_debug)
724 sprintf(msgbuf, "error code %d ", ret.result);
725
726 if (preempt_count() != count) {
727 strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
728 preempt_count() = count;
729 }
730 if (irqs_disabled()) {
731 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
732 local_irq_enable();
733 }
734 if (msgbuf[0]) {
735 printk("initcall %pF returned with %s\n", fn, msgbuf);
736 }
737
738 return ret.result;
739 }
740
741
742 extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
743
do_initcalls(void)744 static void __init do_initcalls(void)
745 {
746 initcall_t *call;
747
748 for (call = __early_initcall_end; call < __initcall_end; call++)
749 do_one_initcall(*call);
750
751 /* Make sure there is no pending stuff from the initcall sequence */
752 flush_scheduled_work();
753 }
754
755 /*
756 * Ok, the machine is now initialized. None of the devices
757 * have been touched yet, but the CPU subsystem is up and
758 * running, and memory and process management works.
759 *
760 * Now we can finally start doing some real work..
761 */
do_basic_setup(void)762 static void __init do_basic_setup(void)
763 {
764 rcu_init_sched(); /* needed by module_init stage. */
765 init_workqueues();
766 usermodehelper_init();
767 driver_init();
768 init_irq_proc();
769 do_initcalls();
770 }
771
do_pre_smp_initcalls(void)772 static void __init do_pre_smp_initcalls(void)
773 {
774 initcall_t *call;
775
776 for (call = __initcall_start; call < __early_initcall_end; call++)
777 do_one_initcall(*call);
778 }
779
run_init_process(char * init_filename)780 static void run_init_process(char *init_filename)
781 {
782 argv_init[0] = init_filename;
783 kernel_execve(init_filename, argv_init, envp_init);
784 }
785
786 /* This is a non __init function. Force it to be noinline otherwise gcc
787 * makes it inline to init() and it becomes part of init.text section
788 */
init_post(void)789 static noinline int init_post(void)
790 {
791 /* need to finish all async __init code before freeing the memory */
792 async_synchronize_full();
793 free_initmem();
794 unlock_kernel();
795 mark_rodata_ro();
796 system_state = SYSTEM_RUNNING;
797 numa_default_policy();
798
799 if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
800 printk(KERN_WARNING "Warning: unable to open an initial console.\n");
801
802 (void) sys_dup(0);
803 (void) sys_dup(0);
804
805 current->signal->flags |= SIGNAL_UNKILLABLE;
806
807 if (ramdisk_execute_command) {
808 run_init_process(ramdisk_execute_command);
809 printk(KERN_WARNING "Failed to execute %s\n",
810 ramdisk_execute_command);
811 }
812
813 /*
814 * We try each of these until one succeeds.
815 *
816 * The Bourne shell can be used instead of init if we are
817 * trying to recover a really broken machine.
818 */
819 if (execute_command) {
820 run_init_process(execute_command);
821 printk(KERN_WARNING "Failed to execute %s. Attempting "
822 "defaults...\n", execute_command);
823 }
824 run_init_process("/sbin/init");
825 run_init_process("/etc/init");
826 run_init_process("/bin/init");
827 run_init_process("/bin/sh");
828
829 panic("No init found. Try passing init= option to kernel.");
830 }
831
kernel_init(void * unused)832 static int __init kernel_init(void * unused)
833 {
834 lock_kernel();
835 /*
836 * init can run on any cpu.
837 */
838 set_cpus_allowed_ptr(current, CPU_MASK_ALL_PTR);
839 /*
840 * Tell the world that we're going to be the grim
841 * reaper of innocent orphaned children.
842 *
843 * We don't want people to have to make incorrect
844 * assumptions about where in the task array this
845 * can be found.
846 */
847 init_pid_ns.child_reaper = current;
848
849 cad_pid = task_pid(current);
850
851 smp_prepare_cpus(setup_max_cpus);
852
853 do_pre_smp_initcalls();
854 start_boot_trace();
855
856 smp_init();
857 sched_init_smp();
858
859 cpuset_init_smp();
860
861 do_basic_setup();
862
863 /*
864 * check if there is an early userspace init. If yes, let it do all
865 * the work
866 */
867
868 if (!ramdisk_execute_command)
869 ramdisk_execute_command = "/init";
870
871 if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
872 ramdisk_execute_command = NULL;
873 prepare_namespace();
874 }
875
876 /*
877 * Ok, we have completed the initial bootup, and
878 * we're essentially up and running. Get rid of the
879 * initmem segments and start the user-mode stuff..
880 */
881
882 init_post();
883 return 0;
884 }
885