Version:  2.0.40 2.2.26 2.4.37 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17

Linux/init/main.c

  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 #include <linux/sched_clock.h>
 78 #include <linux/context_tracking.h>
 79 #include <linux/random.h>
 80 #include <linux/list.h>
 81 
 82 #include <asm/io.h>
 83 #include <asm/bugs.h>
 84 #include <asm/setup.h>
 85 #include <asm/sections.h>
 86 #include <asm/cacheflush.h>
 87 
 88 #ifdef CONFIG_X86_LOCAL_APIC
 89 #include <asm/smp.h>
 90 #endif
 91 
 92 static int kernel_init(void *);
 93 
 94 extern void init_IRQ(void);
 95 extern void fork_init(unsigned long);
 96 extern void radix_tree_init(void);
 97 #ifndef CONFIG_DEBUG_RODATA
 98 static inline void mark_rodata_ro(void) { }
 99 #endif
100 
101 /*
102  * Debug helper: via this flag we know that we are in 'early bootup code'
103  * where only the boot processor is running with IRQ disabled.  This means
104  * two things - IRQ must not be enabled before the flag is cleared and some
105  * operations which are not allowed with IRQ disabled are allowed while the
106  * flag is set.
107  */
108 bool early_boot_irqs_disabled __read_mostly;
109 
110 enum system_states system_state __read_mostly;
111 EXPORT_SYMBOL(system_state);
112 
113 /*
114  * Boot command-line arguments
115  */
116 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
117 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
118 
119 extern void time_init(void);
120 /* Default late time init is NULL. archs can override this later. */
121 void (*__initdata late_time_init)(void);
122 
123 /* Untouched command line saved by arch-specific code. */
124 char __initdata boot_command_line[COMMAND_LINE_SIZE];
125 /* Untouched saved command line (eg. for /proc) */
126 char *saved_command_line;
127 /* Command line for parameter parsing */
128 static char *static_command_line;
129 /* Command line for per-initcall parameter parsing */
130 static char *initcall_command_line;
131 
132 static char *execute_command;
133 static char *ramdisk_execute_command;
134 
135 /*
136  * Used to generate warnings if static_key manipulation functions are used
137  * before jump_label_init is called.
138  */
139 bool static_key_initialized __read_mostly;
140 EXPORT_SYMBOL_GPL(static_key_initialized);
141 
142 /*
143  * If set, this is an indication to the drivers that reset the underlying
144  * device before going ahead with the initialization otherwise driver might
145  * rely on the BIOS and skip the reset operation.
146  *
147  * This is useful if kernel is booting in an unreliable environment.
148  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
149  * skipped and devices will be in unknown state.
150  */
151 unsigned int reset_devices;
152 EXPORT_SYMBOL(reset_devices);
153 
154 static int __init set_reset_devices(char *str)
155 {
156         reset_devices = 1;
157         return 1;
158 }
159 
160 __setup("reset_devices", set_reset_devices);
161 
162 static const char *argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
163 const char *envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
164 static const char *panic_later, *panic_param;
165 
166 extern const struct obs_kernel_param __setup_start[], __setup_end[];
167 
168 static int __init obsolete_checksetup(char *line)
169 {
170         const struct obs_kernel_param *p;
171         int had_early_param = 0;
172 
173         p = __setup_start;
174         do {
175                 int n = strlen(p->str);
176                 if (parameqn(line, p->str, n)) {
177                         if (p->early) {
178                                 /* Already done in parse_early_param?
179                                  * (Needs exact match on param part).
180                                  * Keep iterating, as we can have early
181                                  * params and __setups of same names 8( */
182                                 if (line[n] == '\0' || line[n] == '=')
183                                         had_early_param = 1;
184                         } else if (!p->setup_func) {
185                                 pr_warn("Parameter %s is obsolete, ignored\n",
186                                         p->str);
187                                 return 1;
188                         } else if (p->setup_func(line + n))
189                                 return 1;
190                 }
191                 p++;
192         } while (p < __setup_end);
193 
194         return had_early_param;
195 }
196 
197 /*
198  * This should be approx 2 Bo*oMips to start (note initial shift), and will
199  * still work even if initially too large, it will just take slightly longer
200  */
201 unsigned long loops_per_jiffy = (1<<12);
202 EXPORT_SYMBOL(loops_per_jiffy);
203 
204 static int __init debug_kernel(char *str)
205 {
206         console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
207         return 0;
208 }
209 
210 static int __init quiet_kernel(char *str)
211 {
212         console_loglevel = CONSOLE_LOGLEVEL_QUIET;
213         return 0;
214 }
215 
216 early_param("debug", debug_kernel);
217 early_param("quiet", quiet_kernel);
218 
219 static int __init loglevel(char *str)
220 {
221         int newlevel;
222 
223         /*
224          * Only update loglevel value when a correct setting was passed,
225          * to prevent blind crashes (when loglevel being set to 0) that
226          * are quite hard to debug
227          */
228         if (get_option(&str, &newlevel)) {
229                 console_loglevel = newlevel;
230                 return 0;
231         }
232 
233         return -EINVAL;
234 }
235 
236 early_param("loglevel", loglevel);
237 
238 /* Change NUL term back to "=", to make "param" the whole string. */
239 static int __init repair_env_string(char *param, char *val, const char *unused)
240 {
241         if (val) {
242                 /* param=val or param="val"? */
243                 if (val == param+strlen(param)+1)
244                         val[-1] = '=';
245                 else if (val == param+strlen(param)+2) {
246                         val[-2] = '=';
247                         memmove(val-1, val, strlen(val)+1);
248                         val--;
249                 } else
250                         BUG();
251         }
252         return 0;
253 }
254 
255 /* Anything after -- gets handed straight to init. */
256 static int __init set_init_arg(char *param, char *val, const char *unused)
257 {
258         unsigned int i;
259 
260         if (panic_later)
261                 return 0;
262 
263         repair_env_string(param, val, unused);
264 
265         for (i = 0; argv_init[i]; i++) {
266                 if (i == MAX_INIT_ARGS) {
267                         panic_later = "init";
268                         panic_param = param;
269                         return 0;
270                 }
271         }
272         argv_init[i] = param;
273         return 0;
274 }
275 
276 /*
277  * Unknown boot options get handed to init, unless they look like
278  * unused parameters (modprobe will find them in /proc/cmdline).
279  */
280 static int __init unknown_bootoption(char *param, char *val, const char *unused)
281 {
282         repair_env_string(param, val, unused);
283 
284         /* Handle obsolete-style parameters */
285         if (obsolete_checksetup(param))
286                 return 0;
287 
288         /* Unused module parameter. */
289         if (strchr(param, '.') && (!val || strchr(param, '.') < val))
290                 return 0;
291 
292         if (panic_later)
293                 return 0;
294 
295         if (val) {
296                 /* Environment option */
297                 unsigned int i;
298                 for (i = 0; envp_init[i]; i++) {
299                         if (i == MAX_INIT_ENVS) {
300                                 panic_later = "env";
301                                 panic_param = param;
302                         }
303                         if (!strncmp(param, envp_init[i], val - param))
304                                 break;
305                 }
306                 envp_init[i] = param;
307         } else {
308                 /* Command line option */
309                 unsigned int i;
310                 for (i = 0; argv_init[i]; i++) {
311                         if (i == MAX_INIT_ARGS) {
312                                 panic_later = "init";
313                                 panic_param = param;
314                         }
315                 }
316                 argv_init[i] = param;
317         }
318         return 0;
319 }
320 
321 static int __init init_setup(char *str)
322 {
323         unsigned int i;
324 
325         execute_command = str;
326         /*
327          * In case LILO is going to boot us with default command line,
328          * it prepends "auto" before the whole cmdline which makes
329          * the shell think it should execute a script with such name.
330          * So we ignore all arguments entered _before_ init=... [MJ]
331          */
332         for (i = 1; i < MAX_INIT_ARGS; i++)
333                 argv_init[i] = NULL;
334         return 1;
335 }
336 __setup("init=", init_setup);
337 
338 static int __init rdinit_setup(char *str)
339 {
340         unsigned int i;
341 
342         ramdisk_execute_command = str;
343         /* See "auto" comment in init_setup */
344         for (i = 1; i < MAX_INIT_ARGS; i++)
345                 argv_init[i] = NULL;
346         return 1;
347 }
348 __setup("rdinit=", rdinit_setup);
349 
350 #ifndef CONFIG_SMP
351 static const unsigned int setup_max_cpus = NR_CPUS;
352 #ifdef CONFIG_X86_LOCAL_APIC
353 static void __init smp_init(void)
354 {
355         APIC_init_uniprocessor();
356 }
357 #else
358 #define smp_init()      do { } while (0)
359 #endif
360 
361 static inline void setup_nr_cpu_ids(void) { }
362 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
363 #endif
364 
365 /*
366  * We need to store the untouched command line for future reference.
367  * We also need to store the touched command line since the parameter
368  * parsing is performed in place, and we should allow a component to
369  * store reference of name/value for future reference.
370  */
371 static void __init setup_command_line(char *command_line)
372 {
373         saved_command_line =
374                 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
375         initcall_command_line =
376                 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
377         static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
378         strcpy(saved_command_line, boot_command_line);
379         strcpy(static_command_line, command_line);
380 }
381 
382 /*
383  * We need to finalize in a non-__init function or else race conditions
384  * between the root thread and the init thread may cause start_kernel to
385  * be reaped by free_initmem before the root thread has proceeded to
386  * cpu_idle.
387  *
388  * gcc-3.4 accidentally inlines this function, so use noinline.
389  */
390 
391 static __initdata DECLARE_COMPLETION(kthreadd_done);
392 
393 static noinline void __init_refok rest_init(void)
394 {
395         int pid;
396 
397         rcu_scheduler_starting();
398         /*
399          * We need to spawn init first so that it obtains pid 1, however
400          * the init task will end up wanting to create kthreads, which, if
401          * we schedule it before we create kthreadd, will OOPS.
402          */
403         kernel_thread(kernel_init, NULL, CLONE_FS);
404         numa_default_policy();
405         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
406         rcu_read_lock();
407         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
408         rcu_read_unlock();
409         complete(&kthreadd_done);
410 
411         /*
412          * The boot idle thread must execute schedule()
413          * at least once to get things moving:
414          */
415         init_idle_bootup_task(current);
416         schedule_preempt_disabled();
417         /* Call into cpu_idle with preempt disabled */
418         cpu_startup_entry(CPUHP_ONLINE);
419 }
420 
421 /* Check for early params. */
422 static int __init do_early_param(char *param, char *val, const char *unused)
423 {
424         const struct obs_kernel_param *p;
425 
426         for (p = __setup_start; p < __setup_end; p++) {
427                 if ((p->early && parameq(param, p->str)) ||
428                     (strcmp(param, "console") == 0 &&
429                      strcmp(p->str, "earlycon") == 0)
430                 ) {
431                         if (p->setup_func(val) != 0)
432                                 pr_warn("Malformed early option '%s'\n", param);
433                 }
434         }
435         /* We accept everything at this stage. */
436         return 0;
437 }
438 
439 void __init parse_early_options(char *cmdline)
440 {
441         parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
442 }
443 
444 /* Arch code calls this early on, or if not, just before other parsing. */
445 void __init parse_early_param(void)
446 {
447         static int done __initdata;
448         static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
449 
450         if (done)
451                 return;
452 
453         /* All fall through to do_early_param. */
454         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
455         parse_early_options(tmp_cmdline);
456         done = 1;
457 }
458 
459 /*
460  *      Activate the first processor.
461  */
462 
463 static void __init boot_cpu_init(void)
464 {
465         int cpu = smp_processor_id();
466         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
467         set_cpu_online(cpu, true);
468         set_cpu_active(cpu, true);
469         set_cpu_present(cpu, true);
470         set_cpu_possible(cpu, true);
471 }
472 
473 void __init __weak smp_setup_processor_id(void)
474 {
475 }
476 
477 # if THREAD_SIZE >= PAGE_SIZE
478 void __init __weak thread_info_cache_init(void)
479 {
480 }
481 #endif
482 
483 /*
484  * Set up kernel memory allocators
485  */
486 static void __init mm_init(void)
487 {
488         /*
489          * page_cgroup requires contiguous pages,
490          * bigger than MAX_ORDER unless SPARSEMEM.
491          */
492         page_cgroup_init_flatmem();
493         mem_init();
494         kmem_cache_init();
495         percpu_init_late();
496         pgtable_init();
497         vmalloc_init();
498 }
499 
500 asmlinkage __visible void __init start_kernel(void)
501 {
502         char *command_line;
503         char *after_dashes;
504         extern const struct kernel_param __start___param[], __stop___param[];
505 
506         /*
507          * Need to run as early as possible, to initialize the
508          * lockdep hash:
509          */
510         lockdep_init();
511         smp_setup_processor_id();
512         debug_objects_early_init();
513 
514         /*
515          * Set up the the initial canary ASAP:
516          */
517         boot_init_stack_canary();
518 
519         cgroup_init_early();
520 
521         local_irq_disable();
522         early_boot_irqs_disabled = true;
523 
524 /*
525  * Interrupts are still disabled. Do necessary setups, then
526  * enable them
527  */
528         boot_cpu_init();
529         page_address_init();
530         pr_notice("%s", linux_banner);
531         setup_arch(&command_line);
532         mm_init_cpumask(&init_mm);
533         setup_command_line(command_line);
534         setup_nr_cpu_ids();
535         setup_per_cpu_areas();
536         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
537 
538         build_all_zonelists(NULL, NULL);
539         page_alloc_init();
540 
541         pr_notice("Kernel command line: %s\n", boot_command_line);
542         parse_early_param();
543         after_dashes = parse_args("Booting kernel",
544                                   static_command_line, __start___param,
545                                   __stop___param - __start___param,
546                                   -1, -1, &unknown_bootoption);
547         if (after_dashes)
548                 parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
549                            set_init_arg);
550 
551         jump_label_init();
552 
553         /*
554          * These use large bootmem allocations and must precede
555          * kmem_cache_init()
556          */
557         setup_log_buf(0);
558         pidhash_init();
559         vfs_caches_init_early();
560         sort_main_extable();
561         trap_init();
562         mm_init();
563 
564         /*
565          * Set up the scheduler prior starting any interrupts (such as the
566          * timer interrupt). Full topology setup happens at smp_init()
567          * time - but meanwhile we still have a functioning scheduler.
568          */
569         sched_init();
570         /*
571          * Disable preemption - early bootup scheduling is extremely
572          * fragile until we cpu_idle() for the first time.
573          */
574         preempt_disable();
575         if (WARN(!irqs_disabled(),
576                  "Interrupts were enabled *very* early, fixing it\n"))
577                 local_irq_disable();
578         idr_init_cache();
579         rcu_init();
580         tick_nohz_init();
581         context_tracking_init();
582         radix_tree_init();
583         /* init some links before init_ISA_irqs() */
584         early_irq_init();
585         init_IRQ();
586         tick_init();
587         init_timers();
588         hrtimers_init();
589         softirq_init();
590         timekeeping_init();
591         time_init();
592         sched_clock_postinit();
593         perf_event_init();
594         profile_init();
595         call_function_init();
596         WARN(!irqs_disabled(), "Interrupts were enabled early\n");
597         early_boot_irqs_disabled = false;
598         local_irq_enable();
599 
600         kmem_cache_init_late();
601 
602         /*
603          * HACK ALERT! This is early. We're enabling the console before
604          * we've done PCI setups etc, and console_init() must be aware of
605          * this. But we do want output early, in case something goes wrong.
606          */
607         console_init();
608         if (panic_later)
609                 panic("Too many boot %s vars at `%s'", panic_later,
610                       panic_param);
611 
612         lockdep_info();
613 
614         /*
615          * Need to run this when irqs are enabled, because it wants
616          * to self-test [hard/soft]-irqs on/off lock inversion bugs
617          * too:
618          */
619         locking_selftest();
620 
621 #ifdef CONFIG_BLK_DEV_INITRD
622         if (initrd_start && !initrd_below_start_ok &&
623             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
624                 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
625                     page_to_pfn(virt_to_page((void *)initrd_start)),
626                     min_low_pfn);
627                 initrd_start = 0;
628         }
629 #endif
630         page_cgroup_init();
631         debug_objects_mem_init();
632         kmemleak_init();
633         setup_per_cpu_pageset();
634         numa_policy_init();
635         if (late_time_init)
636                 late_time_init();
637         sched_clock_init();
638         calibrate_delay();
639         pidmap_init();
640         anon_vma_init();
641         acpi_early_init();
642 #ifdef CONFIG_X86
643         if (efi_enabled(EFI_RUNTIME_SERVICES))
644                 efi_enter_virtual_mode();
645 #endif
646 #ifdef CONFIG_X86_ESPFIX64
647         /* Should be run before the first non-init thread is created */
648         init_espfix_bsp();
649 #endif
650         thread_info_cache_init();
651         cred_init();
652         fork_init(totalram_pages);
653         proc_caches_init();
654         buffer_init();
655         key_init();
656         security_init();
657         dbg_late_init();
658         vfs_caches_init(totalram_pages);
659         signals_init();
660         /* rootfs populating might need page-writeback */
661         page_writeback_init();
662         proc_root_init();
663         cgroup_init();
664         cpuset_init();
665         taskstats_init_early();
666         delayacct_init();
667 
668         check_bugs();
669 
670         sfi_init_late();
671 
672         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
673                 efi_late_init();
674                 efi_free_boot_services();
675         }
676 
677         ftrace_init();
678 
679         /* Do the rest non-__init'ed, we're now alive */
680         rest_init();
681 }
682 
683 /* Call all constructor functions linked into the kernel. */
684 static void __init do_ctors(void)
685 {
686 #ifdef CONFIG_CONSTRUCTORS
687         ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
688 
689         for (; fn < (ctor_fn_t *) __ctors_end; fn++)
690                 (*fn)();
691 #endif
692 }
693 
694 bool initcall_debug;
695 core_param(initcall_debug, initcall_debug, bool, 0644);
696 
697 #ifdef CONFIG_KALLSYMS
698 struct blacklist_entry {
699         struct list_head next;
700         char *buf;
701 };
702 
703 static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
704 
705 static int __init initcall_blacklist(char *str)
706 {
707         char *str_entry;
708         struct blacklist_entry *entry;
709 
710         /* str argument is a comma-separated list of functions */
711         do {
712                 str_entry = strsep(&str, ",");
713                 if (str_entry) {
714                         pr_debug("blacklisting initcall %s\n", str_entry);
715                         entry = alloc_bootmem(sizeof(*entry));
716                         entry->buf = alloc_bootmem(strlen(str_entry) + 1);
717                         strcpy(entry->buf, str_entry);
718                         list_add(&entry->next, &blacklisted_initcalls);
719                 }
720         } while (str_entry);
721 
722         return 0;
723 }
724 
725 static bool __init_or_module initcall_blacklisted(initcall_t fn)
726 {
727         struct list_head *tmp;
728         struct blacklist_entry *entry;
729         char *fn_name;
730 
731         fn_name = kasprintf(GFP_KERNEL, "%pf", fn);
732         if (!fn_name)
733                 return false;
734 
735         list_for_each(tmp, &blacklisted_initcalls) {
736                 entry = list_entry(tmp, struct blacklist_entry, next);
737                 if (!strcmp(fn_name, entry->buf)) {
738                         pr_debug("initcall %s blacklisted\n", fn_name);
739                         kfree(fn_name);
740                         return true;
741                 }
742         }
743 
744         kfree(fn_name);
745         return false;
746 }
747 #else
748 static int __init initcall_blacklist(char *str)
749 {
750         pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
751         return 0;
752 }
753 
754 static bool __init_or_module initcall_blacklisted(initcall_t fn)
755 {
756         return false;
757 }
758 #endif
759 __setup("initcall_blacklist=", initcall_blacklist);
760 
761 static int __init_or_module do_one_initcall_debug(initcall_t fn)
762 {
763         ktime_t calltime, delta, rettime;
764         unsigned long long duration;
765         int ret;
766 
767         printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
768         calltime = ktime_get();
769         ret = fn();
770         rettime = ktime_get();
771         delta = ktime_sub(rettime, calltime);
772         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
773         printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n",
774                  fn, ret, duration);
775 
776         return ret;
777 }
778 
779 int __init_or_module do_one_initcall(initcall_t fn)
780 {
781         int count = preempt_count();
782         int ret;
783         char msgbuf[64];
784 
785         if (initcall_blacklisted(fn))
786                 return -EPERM;
787 
788         if (initcall_debug)
789                 ret = do_one_initcall_debug(fn);
790         else
791                 ret = fn();
792 
793         msgbuf[0] = 0;
794 
795         if (preempt_count() != count) {
796                 sprintf(msgbuf, "preemption imbalance ");
797                 preempt_count_set(count);
798         }
799         if (irqs_disabled()) {
800                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
801                 local_irq_enable();
802         }
803         WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
804 
805         return ret;
806 }
807 
808 
809 extern initcall_t __initcall_start[];
810 extern initcall_t __initcall0_start[];
811 extern initcall_t __initcall1_start[];
812 extern initcall_t __initcall2_start[];
813 extern initcall_t __initcall3_start[];
814 extern initcall_t __initcall4_start[];
815 extern initcall_t __initcall5_start[];
816 extern initcall_t __initcall6_start[];
817 extern initcall_t __initcall7_start[];
818 extern initcall_t __initcall_end[];
819 
820 static initcall_t *initcall_levels[] __initdata = {
821         __initcall0_start,
822         __initcall1_start,
823         __initcall2_start,
824         __initcall3_start,
825         __initcall4_start,
826         __initcall5_start,
827         __initcall6_start,
828         __initcall7_start,
829         __initcall_end,
830 };
831 
832 /* Keep these in sync with initcalls in include/linux/init.h */
833 static char *initcall_level_names[] __initdata = {
834         "early",
835         "core",
836         "postcore",
837         "arch",
838         "subsys",
839         "fs",
840         "device",
841         "late",
842 };
843 
844 static void __init do_initcall_level(int level)
845 {
846         extern const struct kernel_param __start___param[], __stop___param[];
847         initcall_t *fn;
848 
849         strcpy(initcall_command_line, saved_command_line);
850         parse_args(initcall_level_names[level],
851                    initcall_command_line, __start___param,
852                    __stop___param - __start___param,
853                    level, level,
854                    &repair_env_string);
855 
856         for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
857                 do_one_initcall(*fn);
858 }
859 
860 static void __init do_initcalls(void)
861 {
862         int level;
863 
864         for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
865                 do_initcall_level(level);
866 }
867 
868 /*
869  * Ok, the machine is now initialized. None of the devices
870  * have been touched yet, but the CPU subsystem is up and
871  * running, and memory and process management works.
872  *
873  * Now we can finally start doing some real work..
874  */
875 static void __init do_basic_setup(void)
876 {
877         cpuset_init_smp();
878         usermodehelper_init();
879         shmem_init();
880         driver_init();
881         init_irq_proc();
882         do_ctors();
883         usermodehelper_enable();
884         do_initcalls();
885         random_int_secret_init();
886 }
887 
888 static void __init do_pre_smp_initcalls(void)
889 {
890         initcall_t *fn;
891 
892         for (fn = __initcall_start; fn < __initcall0_start; fn++)
893                 do_one_initcall(*fn);
894 }
895 
896 /*
897  * This function requests modules which should be loaded by default and is
898  * called twice right after initrd is mounted and right before init is
899  * exec'd.  If such modules are on either initrd or rootfs, they will be
900  * loaded before control is passed to userland.
901  */
902 void __init load_default_modules(void)
903 {
904         load_default_elevator_module();
905 }
906 
907 static int run_init_process(const char *init_filename)
908 {
909         argv_init[0] = init_filename;
910         return do_execve(getname_kernel(init_filename),
911                 (const char __user *const __user *)argv_init,
912                 (const char __user *const __user *)envp_init);
913 }
914 
915 static int try_to_run_init_process(const char *init_filename)
916 {
917         int ret;
918 
919         ret = run_init_process(init_filename);
920 
921         if (ret && ret != -ENOENT) {
922                 pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
923                        init_filename, ret);
924         }
925 
926         return ret;
927 }
928 
929 static noinline void __init kernel_init_freeable(void);
930 
931 static int __ref kernel_init(void *unused)
932 {
933         int ret;
934 
935         kernel_init_freeable();
936         /* need to finish all async __init code before freeing the memory */
937         async_synchronize_full();
938         free_initmem();
939         mark_rodata_ro();
940         system_state = SYSTEM_RUNNING;
941         numa_default_policy();
942 
943         flush_delayed_fput();
944 
945         if (ramdisk_execute_command) {
946                 ret = run_init_process(ramdisk_execute_command);
947                 if (!ret)
948                         return 0;
949                 pr_err("Failed to execute %s (error %d)\n",
950                        ramdisk_execute_command, ret);
951         }
952 
953         /*
954          * We try each of these until one succeeds.
955          *
956          * The Bourne shell can be used instead of init if we are
957          * trying to recover a really broken machine.
958          */
959         if (execute_command) {
960                 ret = run_init_process(execute_command);
961                 if (!ret)
962                         return 0;
963                 pr_err("Failed to execute %s (error %d).  Attempting defaults...\n",
964                         execute_command, ret);
965         }
966         if (!try_to_run_init_process("/sbin/init") ||
967             !try_to_run_init_process("/etc/init") ||
968             !try_to_run_init_process("/bin/init") ||
969             !try_to_run_init_process("/bin/sh"))
970                 return 0;
971 
972         panic("No working init found.  Try passing init= option to kernel. "
973               "See Linux Documentation/init.txt for guidance.");
974 }
975 
976 static noinline void __init kernel_init_freeable(void)
977 {
978         /*
979          * Wait until kthreadd is all set-up.
980          */
981         wait_for_completion(&kthreadd_done);
982 
983         /* Now the scheduler is fully set up and can do blocking allocations */
984         gfp_allowed_mask = __GFP_BITS_MASK;
985 
986         /*
987          * init can allocate pages on any node
988          */
989         set_mems_allowed(node_states[N_MEMORY]);
990         /*
991          * init can run on any cpu.
992          */
993         set_cpus_allowed_ptr(current, cpu_all_mask);
994 
995         cad_pid = task_pid(current);
996 
997         smp_prepare_cpus(setup_max_cpus);
998 
999         do_pre_smp_initcalls();
1000         lockup_detector_init();
1001 
1002         smp_init();
1003         sched_init_smp();
1004 
1005         do_basic_setup();
1006 
1007         /* Open the /dev/console on the rootfs, this should never fail */
1008         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
1009                 pr_err("Warning: unable to open an initial console.\n");
1010 
1011         (void) sys_dup(0);
1012         (void) sys_dup(0);
1013         /*
1014          * check if there is an early userspace init.  If yes, let it do all
1015          * the work
1016          */
1017 
1018         if (!ramdisk_execute_command)
1019                 ramdisk_execute_command = "/init";
1020 
1021         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
1022                 ramdisk_execute_command = NULL;
1023                 prepare_namespace();
1024         }
1025 
1026         /*
1027          * Ok, we have completed the initial bootup, and
1028          * we're essentially up and running. Get rid of the
1029          * initmem segments and start the user-mode stuff..
1030          */
1031 
1032         /* rootfs is available now, try loading default modules */
1033         load_default_modules();
1034 }
1035 

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