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