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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_ext.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 #include <linux/integrity.h>
 82 #include <linux/proc_ns.h>
 83 #include <linux/io.h>
 84 #include <linux/cache.h>
 85 
 86 #include <asm/io.h>
 87 #include <asm/bugs.h>
 88 #include <asm/setup.h>
 89 #include <asm/sections.h>
 90 #include <asm/cacheflush.h>
 91 
 92 static int kernel_init(void *);
 93 
 94 extern void init_IRQ(void);
 95 extern void fork_init(void);
 96 extern void radix_tree_init(void);
 97 
 98 /*
 99  * Debug helper: via this flag we know that we are in 'early bootup code'
100  * where only the boot processor is running with IRQ disabled.  This means
101  * two things - IRQ must not be enabled before the flag is cleared and some
102  * operations which are not allowed with IRQ disabled are allowed while the
103  * flag is set.
104  */
105 bool early_boot_irqs_disabled __read_mostly;
106 
107 enum system_states system_state __read_mostly;
108 EXPORT_SYMBOL(system_state);
109 
110 /*
111  * Boot command-line arguments
112  */
113 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
114 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
115 
116 extern void time_init(void);
117 /* Default late time init is NULL. archs can override this later. */
118 void (*__initdata late_time_init)(void);
119 
120 /* Untouched command line saved by arch-specific code. */
121 char __initdata boot_command_line[COMMAND_LINE_SIZE];
122 /* Untouched saved command line (eg. for /proc) */
123 char *saved_command_line;
124 /* Command line for parameter parsing */
125 static char *static_command_line;
126 /* Command line for per-initcall parameter parsing */
127 static char *initcall_command_line;
128 
129 static char *execute_command;
130 static char *ramdisk_execute_command;
131 
132 /*
133  * Used to generate warnings if static_key manipulation functions are used
134  * before jump_label_init is called.
135  */
136 bool static_key_initialized __read_mostly;
137 EXPORT_SYMBOL_GPL(static_key_initialized);
138 
139 /*
140  * If set, this is an indication to the drivers that reset the underlying
141  * device before going ahead with the initialization otherwise driver might
142  * rely on the BIOS and skip the reset operation.
143  *
144  * This is useful if kernel is booting in an unreliable environment.
145  * For ex. kdump situation where previous kernel has crashed, BIOS has been
146  * skipped and devices will be in unknown state.
147  */
148 unsigned int reset_devices;
149 EXPORT_SYMBOL(reset_devices);
150 
151 static int __init set_reset_devices(char *str)
152 {
153         reset_devices = 1;
154         return 1;
155 }
156 
157 __setup("reset_devices", set_reset_devices);
158 
159 static const char *argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
160 const char *envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
161 static const char *panic_later, *panic_param;
162 
163 extern const struct obs_kernel_param __setup_start[], __setup_end[];
164 
165 static bool __init obsolete_checksetup(char *line)
166 {
167         const struct obs_kernel_param *p;
168         bool had_early_param = false;
169 
170         p = __setup_start;
171         do {
172                 int n = strlen(p->str);
173                 if (parameqn(line, p->str, n)) {
174                         if (p->early) {
175                                 /* Already done in parse_early_param?
176                                  * (Needs exact match on param part).
177                                  * Keep iterating, as we can have early
178                                  * params and __setups of same names 8( */
179                                 if (line[n] == '\0' || line[n] == '=')
180                                         had_early_param = true;
181                         } else if (!p->setup_func) {
182                                 pr_warn("Parameter %s is obsolete, ignored\n",
183                                         p->str);
184                                 return true;
185                         } else if (p->setup_func(line + n))
186                                 return true;
187                 }
188                 p++;
189         } while (p < __setup_end);
190 
191         return had_early_param;
192 }
193 
194 /*
195  * This should be approx 2 Bo*oMips to start (note initial shift), and will
196  * still work even if initially too large, it will just take slightly longer
197  */
198 unsigned long loops_per_jiffy = (1<<12);
199 EXPORT_SYMBOL(loops_per_jiffy);
200 
201 static int __init debug_kernel(char *str)
202 {
203         console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
204         return 0;
205 }
206 
207 static int __init quiet_kernel(char *str)
208 {
209         console_loglevel = CONSOLE_LOGLEVEL_QUIET;
210         return 0;
211 }
212 
213 early_param("debug", debug_kernel);
214 early_param("quiet", quiet_kernel);
215 
216 static int __init loglevel(char *str)
217 {
218         int newlevel;
219 
220         /*
221          * Only update loglevel value when a correct setting was passed,
222          * to prevent blind crashes (when loglevel being set to 0) that
223          * are quite hard to debug
224          */
225         if (get_option(&str, &newlevel)) {
226                 console_loglevel = newlevel;
227                 return 0;
228         }
229 
230         return -EINVAL;
231 }
232 
233 early_param("loglevel", loglevel);
234 
235 /* Change NUL term back to "=", to make "param" the whole string. */
236 static int __init repair_env_string(char *param, char *val,
237                                     const char *unused, void *arg)
238 {
239         if (val) {
240                 /* param=val or param="val"? */
241                 if (val == param+strlen(param)+1)
242                         val[-1] = '=';
243                 else if (val == param+strlen(param)+2) {
244                         val[-2] = '=';
245                         memmove(val-1, val, strlen(val)+1);
246                         val--;
247                 } else
248                         BUG();
249         }
250         return 0;
251 }
252 
253 /* Anything after -- gets handed straight to init. */
254 static int __init set_init_arg(char *param, char *val,
255                                const char *unused, void *arg)
256 {
257         unsigned int i;
258 
259         if (panic_later)
260                 return 0;
261 
262         repair_env_string(param, val, unused, NULL);
263 
264         for (i = 0; argv_init[i]; i++) {
265                 if (i == MAX_INIT_ARGS) {
266                         panic_later = "init";
267                         panic_param = param;
268                         return 0;
269                 }
270         }
271         argv_init[i] = param;
272         return 0;
273 }
274 
275 /*
276  * Unknown boot options get handed to init, unless they look like
277  * unused parameters (modprobe will find them in /proc/cmdline).
278  */
279 static int __init unknown_bootoption(char *param, char *val,
280                                      const char *unused, void *arg)
281 {
282         repair_env_string(param, val, unused, NULL);
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 static inline void setup_nr_cpu_ids(void) { }
353 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
354 #endif
355 
356 /*
357  * We need to store the untouched command line for future reference.
358  * We also need to store the touched command line since the parameter
359  * parsing is performed in place, and we should allow a component to
360  * store reference of name/value for future reference.
361  */
362 static void __init setup_command_line(char *command_line)
363 {
364         saved_command_line =
365                 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
366         initcall_command_line =
367                 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
368         static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
369         strcpy(saved_command_line, boot_command_line);
370         strcpy(static_command_line, command_line);
371 }
372 
373 /*
374  * We need to finalize in a non-__init function or else race conditions
375  * between the root thread and the init thread may cause start_kernel to
376  * be reaped by free_initmem before the root thread has proceeded to
377  * cpu_idle.
378  *
379  * gcc-3.4 accidentally inlines this function, so use noinline.
380  */
381 
382 static __initdata DECLARE_COMPLETION(kthreadd_done);
383 
384 static noinline void __ref rest_init(void)
385 {
386         int pid;
387 
388         rcu_scheduler_starting();
389         /*
390          * We need to spawn init first so that it obtains pid 1, however
391          * the init task will end up wanting to create kthreads, which, if
392          * we schedule it before we create kthreadd, will OOPS.
393          */
394         kernel_thread(kernel_init, NULL, CLONE_FS);
395         numa_default_policy();
396         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
397         rcu_read_lock();
398         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
399         rcu_read_unlock();
400         complete(&kthreadd_done);
401 
402         /*
403          * The boot idle thread must execute schedule()
404          * at least once to get things moving:
405          */
406         init_idle_bootup_task(current);
407         schedule_preempt_disabled();
408         /* Call into cpu_idle with preempt disabled */
409         cpu_startup_entry(CPUHP_ONLINE);
410 }
411 
412 /* Check for early params. */
413 static int __init do_early_param(char *param, char *val,
414                                  const char *unused, void *arg)
415 {
416         const struct obs_kernel_param *p;
417 
418         for (p = __setup_start; p < __setup_end; p++) {
419                 if ((p->early && parameq(param, p->str)) ||
420                     (strcmp(param, "console") == 0 &&
421                      strcmp(p->str, "earlycon") == 0)
422                 ) {
423                         if (p->setup_func(val) != 0)
424                                 pr_warn("Malformed early option '%s'\n", param);
425                 }
426         }
427         /* We accept everything at this stage. */
428         return 0;
429 }
430 
431 void __init parse_early_options(char *cmdline)
432 {
433         parse_args("early options", cmdline, NULL, 0, 0, 0, NULL,
434                    do_early_param);
435 }
436 
437 /* Arch code calls this early on, or if not, just before other parsing. */
438 void __init parse_early_param(void)
439 {
440         static int done __initdata;
441         static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
442 
443         if (done)
444                 return;
445 
446         /* All fall through to do_early_param. */
447         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
448         parse_early_options(tmp_cmdline);
449         done = 1;
450 }
451 
452 void __init __weak arch_post_acpi_subsys_init(void) { }
453 
454 void __init __weak smp_setup_processor_id(void)
455 {
456 }
457 
458 # if THREAD_SIZE >= PAGE_SIZE
459 void __init __weak thread_stack_cache_init(void)
460 {
461 }
462 #endif
463 
464 /*
465  * Set up kernel memory allocators
466  */
467 static void __init mm_init(void)
468 {
469         /*
470          * page_ext requires contiguous pages,
471          * bigger than MAX_ORDER unless SPARSEMEM.
472          */
473         page_ext_init_flatmem();
474         mem_init();
475         kmem_cache_init();
476         percpu_init_late();
477         pgtable_init();
478         vmalloc_init();
479         ioremap_huge_init();
480 }
481 
482 asmlinkage __visible void __init start_kernel(void)
483 {
484         char *command_line;
485         char *after_dashes;
486 
487         set_task_stack_end_magic(&init_task);
488         smp_setup_processor_id();
489         debug_objects_early_init();
490 
491         /*
492          * Set up the the initial canary ASAP:
493          */
494         boot_init_stack_canary();
495 
496         cgroup_init_early();
497 
498         local_irq_disable();
499         early_boot_irqs_disabled = true;
500 
501 /*
502  * Interrupts are still disabled. Do necessary setups, then
503  * enable them
504  */
505         boot_cpu_init();
506         page_address_init();
507         pr_notice("%s", linux_banner);
508         setup_arch(&command_line);
509         mm_init_cpumask(&init_mm);
510         setup_command_line(command_line);
511         setup_nr_cpu_ids();
512         setup_per_cpu_areas();
513         boot_cpu_state_init();
514         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
515 
516         build_all_zonelists(NULL, NULL);
517         page_alloc_init();
518 
519         pr_notice("Kernel command line: %s\n", boot_command_line);
520         parse_early_param();
521         after_dashes = parse_args("Booting kernel",
522                                   static_command_line, __start___param,
523                                   __stop___param - __start___param,
524                                   -1, -1, NULL, &unknown_bootoption);
525         if (!IS_ERR_OR_NULL(after_dashes))
526                 parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
527                            NULL, set_init_arg);
528 
529         jump_label_init();
530 
531         /*
532          * These use large bootmem allocations and must precede
533          * kmem_cache_init()
534          */
535         setup_log_buf(0);
536         pidhash_init();
537         vfs_caches_init_early();
538         sort_main_extable();
539         trap_init();
540         mm_init();
541 
542         /*
543          * Set up the scheduler prior starting any interrupts (such as the
544          * timer interrupt). Full topology setup happens at smp_init()
545          * time - but meanwhile we still have a functioning scheduler.
546          */
547         sched_init();
548         /*
549          * Disable preemption - early bootup scheduling is extremely
550          * fragile until we cpu_idle() for the first time.
551          */
552         preempt_disable();
553         if (WARN(!irqs_disabled(),
554                  "Interrupts were enabled *very* early, fixing it\n"))
555                 local_irq_disable();
556         idr_init_cache();
557 
558         /*
559          * Allow workqueue creation and work item queueing/cancelling
560          * early.  Work item execution depends on kthreads and starts after
561          * workqueue_init().
562          */
563         workqueue_init_early();
564 
565         rcu_init();
566 
567         /* trace_printk() and trace points may be used after this */
568         trace_init();
569 
570         context_tracking_init();
571         radix_tree_init();
572         /* init some links before init_ISA_irqs() */
573         early_irq_init();
574         init_IRQ();
575         tick_init();
576         rcu_init_nohz();
577         init_timers();
578         hrtimers_init();
579         softirq_init();
580         timekeeping_init();
581         time_init();
582         sched_clock_postinit();
583         printk_nmi_init();
584         perf_event_init();
585         profile_init();
586         call_function_init();
587         WARN(!irqs_disabled(), "Interrupts were enabled early\n");
588         early_boot_irqs_disabled = false;
589         local_irq_enable();
590 
591         kmem_cache_init_late();
592 
593         /*
594          * HACK ALERT! This is early. We're enabling the console before
595          * we've done PCI setups etc, and console_init() must be aware of
596          * this. But we do want output early, in case something goes wrong.
597          */
598         console_init();
599         if (panic_later)
600                 panic("Too many boot %s vars at `%s'", panic_later,
601                       panic_param);
602 
603         lockdep_info();
604 
605         /*
606          * Need to run this when irqs are enabled, because it wants
607          * to self-test [hard/soft]-irqs on/off lock inversion bugs
608          * too:
609          */
610         locking_selftest();
611 
612 #ifdef CONFIG_BLK_DEV_INITRD
613         if (initrd_start && !initrd_below_start_ok &&
614             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
615                 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
616                     page_to_pfn(virt_to_page((void *)initrd_start)),
617                     min_low_pfn);
618                 initrd_start = 0;
619         }
620 #endif
621         page_ext_init();
622         debug_objects_mem_init();
623         kmemleak_init();
624         setup_per_cpu_pageset();
625         numa_policy_init();
626         if (late_time_init)
627                 late_time_init();
628         sched_clock_init();
629         calibrate_delay();
630         pidmap_init();
631         anon_vma_init();
632         acpi_early_init();
633 #ifdef CONFIG_X86
634         if (efi_enabled(EFI_RUNTIME_SERVICES))
635                 efi_enter_virtual_mode();
636 #endif
637 #ifdef CONFIG_X86_ESPFIX64
638         /* Should be run before the first non-init thread is created */
639         init_espfix_bsp();
640 #endif
641         thread_stack_cache_init();
642         cred_init();
643         fork_init();
644         proc_caches_init();
645         buffer_init();
646         key_init();
647         security_init();
648         dbg_late_init();
649         vfs_caches_init();
650         pagecache_init();
651         signals_init();
652         proc_root_init();
653         nsfs_init();
654         cpuset_init();
655         cgroup_init();
656         taskstats_init_early();
657         delayacct_init();
658 
659         check_bugs();
660 
661         acpi_subsystem_init();
662         arch_post_acpi_subsys_init();
663         sfi_init_late();
664 
665         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
666                 efi_late_init();
667                 efi_free_boot_services();
668         }
669 
670         ftrace_init();
671 
672         /* Do the rest non-__init'ed, we're now alive */
673         rest_init();
674 }
675 
676 /* Call all constructor functions linked into the kernel. */
677 static void __init do_ctors(void)
678 {
679 #ifdef CONFIG_CONSTRUCTORS
680         ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
681 
682         for (; fn < (ctor_fn_t *) __ctors_end; fn++)
683                 (*fn)();
684 #endif
685 }
686 
687 bool initcall_debug;
688 core_param(initcall_debug, initcall_debug, bool, 0644);
689 
690 #ifdef CONFIG_KALLSYMS
691 struct blacklist_entry {
692         struct list_head next;
693         char *buf;
694 };
695 
696 static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
697 
698 static int __init initcall_blacklist(char *str)
699 {
700         char *str_entry;
701         struct blacklist_entry *entry;
702 
703         /* str argument is a comma-separated list of functions */
704         do {
705                 str_entry = strsep(&str, ",");
706                 if (str_entry) {
707                         pr_debug("blacklisting initcall %s\n", str_entry);
708                         entry = alloc_bootmem(sizeof(*entry));
709                         entry->buf = alloc_bootmem(strlen(str_entry) + 1);
710                         strcpy(entry->buf, str_entry);
711                         list_add(&entry->next, &blacklisted_initcalls);
712                 }
713         } while (str_entry);
714 
715         return 0;
716 }
717 
718 static bool __init_or_module initcall_blacklisted(initcall_t fn)
719 {
720         struct blacklist_entry *entry;
721         char fn_name[KSYM_SYMBOL_LEN];
722         unsigned long addr;
723 
724         if (list_empty(&blacklisted_initcalls))
725                 return false;
726 
727         addr = (unsigned long) dereference_function_descriptor(fn);
728         sprint_symbol_no_offset(fn_name, addr);
729 
730         /*
731          * fn will be "function_name [module_name]" where [module_name] is not
732          * displayed for built-in init functions.  Strip off the [module_name].
733          */
734         strreplace(fn_name, ' ', '\0');
735 
736         list_for_each_entry(entry, &blacklisted_initcalls, next) {
737                 if (!strcmp(fn_name, entry->buf)) {
738                         pr_debug("initcall %s blacklisted\n", fn_name);
739                         return true;
740                 }
741         }
742 
743         return false;
744 }
745 #else
746 static int __init initcall_blacklist(char *str)
747 {
748         pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
749         return 0;
750 }
751 
752 static bool __init_or_module initcall_blacklisted(initcall_t fn)
753 {
754         return false;
755 }
756 #endif
757 __setup("initcall_blacklist=", initcall_blacklist);
758 
759 static int __init_or_module do_one_initcall_debug(initcall_t fn)
760 {
761         ktime_t calltime, delta, rettime;
762         unsigned long long duration;
763         int ret;
764 
765         printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
766         calltime = ktime_get();
767         ret = fn();
768         rettime = ktime_get();
769         delta = ktime_sub(rettime, calltime);
770         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
771         printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n",
772                  fn, ret, duration);
773 
774         return ret;
775 }
776 
777 int __init_or_module do_one_initcall(initcall_t fn)
778 {
779         int count = preempt_count();
780         int ret;
781         char msgbuf[64];
782 
783         if (initcall_blacklisted(fn))
784                 return -EPERM;
785 
786         if (initcall_debug)
787                 ret = do_one_initcall_debug(fn);
788         else
789                 ret = fn();
790 
791         msgbuf[0] = 0;
792 
793         if (preempt_count() != count) {
794                 sprintf(msgbuf, "preemption imbalance ");
795                 preempt_count_set(count);
796         }
797         if (irqs_disabled()) {
798                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
799                 local_irq_enable();
800         }
801         WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
802 
803         add_latent_entropy();
804         return ret;
805 }
806 
807 
808 extern initcall_t __initcall_start[];
809 extern initcall_t __initcall0_start[];
810 extern initcall_t __initcall1_start[];
811 extern initcall_t __initcall2_start[];
812 extern initcall_t __initcall3_start[];
813 extern initcall_t __initcall4_start[];
814 extern initcall_t __initcall5_start[];
815 extern initcall_t __initcall6_start[];
816 extern initcall_t __initcall7_start[];
817 extern initcall_t __initcall_end[];
818 
819 static initcall_t *initcall_levels[] __initdata = {
820         __initcall0_start,
821         __initcall1_start,
822         __initcall2_start,
823         __initcall3_start,
824         __initcall4_start,
825         __initcall5_start,
826         __initcall6_start,
827         __initcall7_start,
828         __initcall_end,
829 };
830 
831 /* Keep these in sync with initcalls in include/linux/init.h */
832 static char *initcall_level_names[] __initdata = {
833         "early",
834         "core",
835         "postcore",
836         "arch",
837         "subsys",
838         "fs",
839         "device",
840         "late",
841 };
842 
843 static void __init do_initcall_level(int level)
844 {
845         initcall_t *fn;
846 
847         strcpy(initcall_command_line, saved_command_line);
848         parse_args(initcall_level_names[level],
849                    initcall_command_line, __start___param,
850                    __stop___param - __start___param,
851                    level, level,
852                    NULL, &repair_env_string);
853 
854         for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
855                 do_one_initcall(*fn);
856 }
857 
858 static void __init do_initcalls(void)
859 {
860         int level;
861 
862         for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
863                 do_initcall_level(level);
864 }
865 
866 /*
867  * Ok, the machine is now initialized. None of the devices
868  * have been touched yet, but the CPU subsystem is up and
869  * running, and memory and process management works.
870  *
871  * Now we can finally start doing some real work..
872  */
873 static void __init do_basic_setup(void)
874 {
875         cpuset_init_smp();
876         shmem_init();
877         driver_init();
878         init_irq_proc();
879         do_ctors();
880         usermodehelper_enable();
881         do_initcalls();
882         random_int_secret_init();
883 }
884 
885 static void __init do_pre_smp_initcalls(void)
886 {
887         initcall_t *fn;
888 
889         for (fn = __initcall_start; fn < __initcall0_start; fn++)
890                 do_one_initcall(*fn);
891 }
892 
893 /*
894  * This function requests modules which should be loaded by default and is
895  * called twice right after initrd is mounted and right before init is
896  * exec'd.  If such modules are on either initrd or rootfs, they will be
897  * loaded before control is passed to userland.
898  */
899 void __init load_default_modules(void)
900 {
901         load_default_elevator_module();
902 }
903 
904 static int run_init_process(const char *init_filename)
905 {
906         argv_init[0] = init_filename;
907         return do_execve(getname_kernel(init_filename),
908                 (const char __user *const __user *)argv_init,
909                 (const char __user *const __user *)envp_init);
910 }
911 
912 static int try_to_run_init_process(const char *init_filename)
913 {
914         int ret;
915 
916         ret = run_init_process(init_filename);
917 
918         if (ret && ret != -ENOENT) {
919                 pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
920                        init_filename, ret);
921         }
922 
923         return ret;
924 }
925 
926 static noinline void __init kernel_init_freeable(void);
927 
928 #if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
929 bool rodata_enabled __ro_after_init = true;
930 static int __init set_debug_rodata(char *str)
931 {
932         return strtobool(str, &rodata_enabled);
933 }
934 __setup("rodata=", set_debug_rodata);
935 #endif
936 
937 #ifdef CONFIG_DEBUG_RODATA
938 static void mark_readonly(void)
939 {
940         if (rodata_enabled)
941                 mark_rodata_ro();
942         else
943                 pr_info("Kernel memory protection disabled.\n");
944 }
945 #else
946 static inline void mark_readonly(void)
947 {
948         pr_warn("This architecture does not have kernel memory protection.\n");
949 }
950 #endif
951 
952 static int __ref kernel_init(void *unused)
953 {
954         int ret;
955 
956         kernel_init_freeable();
957         /* need to finish all async __init code before freeing the memory */
958         async_synchronize_full();
959         free_initmem();
960         mark_readonly();
961         system_state = SYSTEM_RUNNING;
962         numa_default_policy();
963 
964         flush_delayed_fput();
965 
966         rcu_end_inkernel_boot();
967 
968         if (ramdisk_execute_command) {
969                 ret = run_init_process(ramdisk_execute_command);
970                 if (!ret)
971                         return 0;
972                 pr_err("Failed to execute %s (error %d)\n",
973                        ramdisk_execute_command, ret);
974         }
975 
976         /*
977          * We try each of these until one succeeds.
978          *
979          * The Bourne shell can be used instead of init if we are
980          * trying to recover a really broken machine.
981          */
982         if (execute_command) {
983                 ret = run_init_process(execute_command);
984                 if (!ret)
985                         return 0;
986                 panic("Requested init %s failed (error %d).",
987                       execute_command, ret);
988         }
989         if (!try_to_run_init_process("/sbin/init") ||
990             !try_to_run_init_process("/etc/init") ||
991             !try_to_run_init_process("/bin/init") ||
992             !try_to_run_init_process("/bin/sh"))
993                 return 0;
994 
995         panic("No working init found.  Try passing init= option to kernel. "
996               "See Linux Documentation/admin-guide/init.rst for guidance.");
997 }
998 
999 static noinline void __init kernel_init_freeable(void)
1000 {
1001         /*
1002          * Wait until kthreadd is all set-up.
1003          */
1004         wait_for_completion(&kthreadd_done);
1005 
1006         /* Now the scheduler is fully set up and can do blocking allocations */
1007         gfp_allowed_mask = __GFP_BITS_MASK;
1008 
1009         /*
1010          * init can allocate pages on any node
1011          */
1012         set_mems_allowed(node_states[N_MEMORY]);
1013         /*
1014          * init can run on any cpu.
1015          */
1016         set_cpus_allowed_ptr(current, cpu_all_mask);
1017 
1018         cad_pid = task_pid(current);
1019 
1020         smp_prepare_cpus(setup_max_cpus);
1021 
1022         workqueue_init();
1023 
1024         do_pre_smp_initcalls();
1025         lockup_detector_init();
1026 
1027         smp_init();
1028         sched_init_smp();
1029 
1030         page_alloc_init_late();
1031 
1032         do_basic_setup();
1033 
1034         /* Open the /dev/console on the rootfs, this should never fail */
1035         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
1036                 pr_err("Warning: unable to open an initial console.\n");
1037 
1038         (void) sys_dup(0);
1039         (void) sys_dup(0);
1040         /*
1041          * check if there is an early userspace init.  If yes, let it do all
1042          * the work
1043          */
1044 
1045         if (!ramdisk_execute_command)
1046                 ramdisk_execute_command = "/init";
1047 
1048         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
1049                 ramdisk_execute_command = NULL;
1050                 prepare_namespace();
1051         }
1052 
1053         /*
1054          * Ok, we have completed the initial bootup, and
1055          * we're essentially up and running. Get rid of the
1056          * initmem segments and start the user-mode stuff..
1057          *
1058          * rootfs is available now, try loading the public keys
1059          * and default modules
1060          */
1061 
1062         integrity_load_keys();
1063         load_default_modules();
1064 }
1065 

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