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 #include <linux/types.h>
  13 #include <linux/module.h>
  14 #include <linux/proc_fs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/stackprotector.h>
  18 #include <linux/string.h>
  19 #include <linux/ctype.h>
  20 #include <linux/delay.h>
  21 #include <linux/utsname.h>
  22 #include <linux/ioport.h>
  23 #include <linux/init.h>
  24 #include <linux/smp_lock.h>
  25 #include <linux/initrd.h>
  26 #include <linux/bootmem.h>
  27 #include <linux/acpi.h>
  28 #include <linux/tty.h>
  29 #include <linux/gfp.h>
  30 #include <linux/percpu.h>
  31 #include <linux/kmod.h>
  32 #include <linux/vmalloc.h>
  33 #include <linux/kernel_stat.h>
  34 #include <linux/start_kernel.h>
  35 #include <linux/security.h>
  36 #include <linux/smp.h>
  37 #include <linux/workqueue.h>
  38 #include <linux/profile.h>
  39 #include <linux/rcupdate.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/kallsyms.h>
  42 #include <linux/writeback.h>
  43 #include <linux/cpu.h>
  44 #include <linux/cpuset.h>
  45 #include <linux/cgroup.h>
  46 #include <linux/efi.h>
  47 #include <linux/tick.h>
  48 #include <linux/interrupt.h>
  49 #include <linux/taskstats_kern.h>
  50 #include <linux/delayacct.h>
  51 #include <linux/unistd.h>
  52 #include <linux/rmap.h>
  53 #include <linux/mempolicy.h>
  54 #include <linux/key.h>
  55 #include <linux/buffer_head.h>
  56 #include <linux/page_cgroup.h>
  57 #include <linux/debug_locks.h>
  58 #include <linux/debugobjects.h>
  59 #include <linux/lockdep.h>
  60 #include <linux/kmemleak.h>
  61 #include <linux/pid_namespace.h>
  62 #include <linux/device.h>
  63 #include <linux/kthread.h>
  64 #include <linux/sched.h>
  65 #include <linux/signal.h>
  66 #include <linux/idr.h>
  67 #include <linux/ftrace.h>
  68 #include <linux/async.h>
  69 #include <linux/kmemcheck.h>
  70 #include <linux/kmemtrace.h>
  71 #include <linux/sfi.h>
  72 #include <linux/shmem_fs.h>
  73 #include <trace/boot.h>
  74
  75 #include <asm/io.h>
  76 #include <asm/bugs.h>
  77 #include <asm/setup.h>
  78 #include <asm/sections.h>
  79 #include <asm/cacheflush.h>
  80
  81 #ifdef CONFIG_X86_LOCAL_APIC
  82 #include <asm/smp.h>
  83 #endif
  84
  85 static int kernel_init(void *);
  86
  87 extern void init_IRQ(void);
  88 extern void fork_init(unsigned long);
  89 extern void mca_init(void);
  90 extern void sbus_init(void);
  91 extern void prio_tree_init(void);
  92 extern void radix_tree_init(void);
  93 extern void free_initmem(void);
  94 #ifndef CONFIG_DEBUG_RODATA
  95 static inline void mark_rodata_ro(void) { }
  96 #endif
  97
  98 #ifdef CONFIG_TC
  99 extern void tc_init(void);
 100 #endif
 101
 102 enum system_states system_state __read_mostly;
 103 EXPORT_SYMBOL(system_state);
 104
 105 /*
 106  * Boot command-line arguments
 107  */
 108 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 109 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 110
 111 extern void time_init(void);
 112 /* Default late time init is NULL. archs can override this later. */
 113 void (*__initdata late_time_init)(void);
 114 extern void softirq_init(void);
 115
 116 /* Untouched command line saved by arch-specific code. */
 117 char __initdata boot_command_line[COMMAND_LINE_SIZE];
 118 /* Untouched saved command line (eg. for /proc) */
 119 char *saved_command_line;
 120 /* Command line for parameter parsing */
 121 static char *static_command_line;
 122
 123 static char *execute_command;
 124 static char *ramdisk_execute_command;
 125
 126 #ifdef CONFIG_SMP
 127 /* Setup configured maximum number of CPUs to activate */
 128 unsigned int __initdata setup_max_cpus = NR_CPUS;
 129
 130 /*
 131  * Setup routine for controlling SMP activation
 132  *
 133  * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 134  * activation entirely (the MPS table probe still happens, though).
 135  *
 136  * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 137  * greater than 0, limits the maximum number of CPUs activated in
 138  * SMP mode to <NUM>.
 139  */
 140
 141 void __weak arch_disable_smp_support(void) { }
 142
 143 static int __init nosmp(char *str)
 144 {
 145         setup_max_cpus = 0;
 146         arch_disable_smp_support();
 147
 148         return 0;
 149 }
 150
 151 early_param("nosmp", nosmp);
 152
 153 static int __init maxcpus(char *str)
 154 {
 155         get_option(&str, &setup_max_cpus);
 156         if (setup_max_cpus == 0)
 157                 arch_disable_smp_support();
 158
 159         return 0;
 160 }
 161
 162 early_param("maxcpus", maxcpus);
 163 #else
 164 const unsigned int setup_max_cpus = NR_CPUS;
 165 #endif
 166
 167 /*
 168  * If set, this is an indication to the drivers that reset the underlying
 169  * device before going ahead with the initialization otherwise driver might
 170  * rely on the BIOS and skip the reset operation.
 171  *
 172  * This is useful if kernel is booting in an unreliable environment.
 173  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 174  * skipped and devices will be in unknown state.
 175  */
 176 unsigned int reset_devices;
 177 EXPORT_SYMBOL(reset_devices);
 178
 179 static int __init set_reset_devices(char *str)
 180 {
 181         reset_devices = 1;
 182         return 1;
 183 }
 184
 185 __setup("reset_devices", set_reset_devices);
 186
 187 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 188 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 189 static const char *panic_later, *panic_param;
 190
 191 extern struct obs_kernel_param __setup_start[], __setup_end[];
 192
 193 static int __init obsolete_checksetup(char *line)
 194 {
 195         struct obs_kernel_param *p;
 196         int had_early_param = 0;
 197
 198         p = __setup_start;
 199         do {
 200                 int n = strlen(p->str);
 201                 if (!strncmp(line, p->str, n)) {
 202                         if (p->early) {
 203                                 /* Already done in parse_early_param?
 204                                  * (Needs exact match on param part).
 205                                  * Keep iterating, as we can have early
 206                                  * params and __setups of same names 8( */
 207                                 if (line[n] == '\0' || line[n] == '=')
 208                                         had_early_param = 1;
 209                         } else if (!p->setup_func) {
 210                                 printk(KERN_WARNING "Parameter %s is obsolete,"
 211                                        " ignored\n", p->str);
 212                                 return 1;
 213                         } else if (p->setup_func(line + n))
 214                                 return 1;
 215                 }
 216                 p++;
 217         } while (p < __setup_end);
 218
 219         return had_early_param;
 220 }
 221
 222 /*
 223  * This should be approx 2 Bo*oMips to start (note initial shift), and will
 224  * still work even if initially too large, it will just take slightly longer
 225  */
 226 unsigned long loops_per_jiffy = (1<<12);
 227
 228 EXPORT_SYMBOL(loops_per_jiffy);
 229
 230 static int __init debug_kernel(char *str)
 231 {
 232         console_loglevel = 10;
 233         return 0;
 234 }
 235
 236 static int __init quiet_kernel(char *str)
 237 {
 238         console_loglevel = 4;
 239         return 0;
 240 }
 241
 242 early_param("debug", debug_kernel);
 243 early_param("quiet", quiet_kernel);
 244
 245 static int __init loglevel(char *str)
 246 {
 247         get_option(&str, &console_loglevel);
 248         return 0;
 249 }
 250
 251 early_param("loglevel", loglevel);
 252
 253 /*
 254  * Unknown boot options get handed to init, unless they look like
 255  * failed parameters
 256  */
 257 static int __init unknown_bootoption(char *param, char *val)
 258 {
 259         /* Change NUL term back to "=", to make "param" the whole string. */
 260         if (val) {
 261                 /* param=val or param="val"? */
 262                 if (val == param+strlen(param)+1)
 263                         val[-1] = '=';
 264                 else if (val == param+strlen(param)+2) {
 265                         val[-2] = '=';
 266                         memmove(val-1, val, strlen(val)+1);
 267                         val--;
 268                 } else
 269                         BUG();
 270         }
 271
 272         /* Handle obsolete-style parameters */
 273         if (obsolete_checksetup(param))
 274                 return 0;
 275
 276         /*
 277          * Preemptive maintenance for "why didn't my misspelled command
 278          * line work?"
 279          */
 280         if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
 281                 printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
 282                 return 0;
 283         }
 284
 285         if (panic_later)
 286                 return 0;
 287
 288         if (val) {
 289                 /* Environment option */
 290                 unsigned int i;
 291                 for (i = 0; envp_init[i]; i++) {
 292                         if (i == MAX_INIT_ENVS) {
 293                                 panic_later = "Too many boot env vars at `%s'";
 294                                 panic_param = param;
 295                         }
 296                         if (!strncmp(param, envp_init[i], val - param))
 297                                 break;
 298                 }
 299                 envp_init[i] = param;
 300         } else {
 301                 /* Command line option */
 302                 unsigned int i;
 303                 for (i = 0; argv_init[i]; i++) {
 304                         if (i == MAX_INIT_ARGS) {
 305                                 panic_later = "Too many boot init vars at `%s'";
 306                                 panic_param = param;
 307                         }
 308                 }
 309                 argv_init[i] = param;
 310         }
 311         return 0;
 312 }
 313
 314 #ifdef CONFIG_DEBUG_PAGEALLOC
 315 int __read_mostly debug_pagealloc_enabled = 0;
 316 #endif
 317
 318 static int __init init_setup(char *str)
 319 {
 320         unsigned int i;
 321
 322         execute_command = str;
 323         /*
 324          * In case LILO is going to boot us with default command line,
 325          * it prepends "auto" before the whole cmdline which makes
 326          * the shell think it should execute a script with such name.
 327          * So we ignore all arguments entered _before_ init=... [MJ]
 328          */
 329         for (i = 1; i < MAX_INIT_ARGS; i++)
 330                 argv_init[i] = NULL;
 331         return 1;
 332 }
 333 __setup("init=", init_setup);
 334
 335 static int __init rdinit_setup(char *str)
 336 {
 337         unsigned int i;
 338
 339         ramdisk_execute_command = str;
 340         /* See "auto" comment in init_setup */
 341         for (i = 1; i < MAX_INIT_ARGS; i++)
 342                 argv_init[i] = NULL;
 343         return 1;
 344 }
 345 __setup("rdinit=", rdinit_setup);
 346
 347 #ifndef CONFIG_SMP
 348
 349 #ifdef CONFIG_X86_LOCAL_APIC
 350 static void __init smp_init(void)
 351 {
 352         APIC_init_uniprocessor();
 353 }
 354 #else
 355 #define smp_init()      do { } while (0)
 356 #endif
 357
 358 static inline void setup_nr_cpu_ids(void) { }
 359 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 360
 361 #else
 362
 363 #if NR_CPUS > BITS_PER_LONG
 364 cpumask_t cpu_mask_all __read_mostly = CPU_MASK_ALL;
 365 EXPORT_SYMBOL(cpu_mask_all);
 366 #endif
 367
 368 /* Setup number of possible processor ids */
 369 int nr_cpu_ids __read_mostly = NR_CPUS;
 370 EXPORT_SYMBOL(nr_cpu_ids);
 371
 372 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
 373 static void __init setup_nr_cpu_ids(void)
 374 {
 375         nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
 376 }
 377
 378 /* Called by boot processor to activate the rest. */
 379 static void __init smp_init(void)
 380 {
 381         unsigned int cpu;
 382
 383         /*
 384          * Set up the current CPU as possible to migrate to.
 385          * The other ones will be done by cpu_up/cpu_down()
 386          */
 387         set_cpu_active(smp_processor_id(), true);
 388
 389         /* FIXME: This should be done in userspace --RR */
 390         for_each_present_cpu(cpu) {
 391                 if (num_online_cpus() >= setup_max_cpus)
 392                         break;
 393                 if (!cpu_online(cpu))
 394                         cpu_up(cpu);
 395         }
 396
 397         /* Any cleanup work */
 398         printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
 399         smp_cpus_done(setup_max_cpus);
 400 }
 401
 402 #endif
 403
 404 /*
 405  * We need to store the untouched command line for future reference.
 406  * We also need to store the touched command line since the parameter
 407  * parsing is performed in place, and we should allow a component to
 408  * store reference of name/value for future reference.
 409  */
 410 static void __init setup_command_line(char *command_line)
 411 {
 412         saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 413         static_command_line = alloc_bootmem(strlen (command_line)+1);
 414         strcpy (saved_command_line, boot_command_line);
 415         strcpy (static_command_line, command_line);
 416 }
 417
 418 /*
 419  * We need to finalize in a non-__init function or else race conditions
 420  * between the root thread and the init thread may cause start_kernel to
 421  * be reaped by free_initmem before the root thread has proceeded to
 422  * cpu_idle.
 423  *
 424  * gcc-3.4 accidentally inlines this function, so use noinline.
 425  */
 426
 427 static noinline void __init_refok rest_init(void)
 428         __releases(kernel_lock)
 429 {
 430         int pid;
 431
 432         rcu_scheduler_starting();
 433         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 434         numa_default_policy();
 435         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 436         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 437         unlock_kernel();
 438
 439         /*
 440          * The boot idle thread must execute schedule()
 441          * at least once to get things moving:
 442          */
 443         init_idle_bootup_task(current);
 444         preempt_enable_no_resched();
 445         schedule();
 446         preempt_disable();
 447
 448         /* Call into cpu_idle with preempt disabled */
 449         cpu_idle();
 450 }
 451
 452 /* Check for early params. */
 453 static int __init do_early_param(char *param, char *val)
 454 {
 455         struct obs_kernel_param *p;
 456
 457         for (p = __setup_start; p < __setup_end; p++) {
 458                 if ((p->early && strcmp(param, p->str) == 0) ||
 459                     (strcmp(param, "console") == 0 &&
 460                      strcmp(p->str, "earlycon") == 0)
 461                 ) {
 462                         if (p->setup_func(val) != 0)
 463                                 printk(KERN_WARNING
 464                                        "Malformed early option '%s'\n", param);
 465                 }
 466         }
 467         /* We accept everything at this stage. */
 468         return 0;
 469 }
 470
 471 void __init parse_early_options(char *cmdline)
 472 {
 473         parse_args("early options", cmdline, NULL, 0, do_early_param);
 474 }
 475
 476 /* Arch code calls this early on, or if not, just before other parsing. */
 477 void __init parse_early_param(void)
 478 {
 479         static __initdata int done = 0;
 480         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 481
 482         if (done)
 483                 return;
 484
 485         /* All fall through to do_early_param. */
 486         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 487         parse_early_options(tmp_cmdline);
 488         done = 1;
 489 }
 490
 491 /*
 492  *      Activate the first processor.
 493  */
 494
 495 static void __init boot_cpu_init(void)
 496 {
 497         int cpu = smp_processor_id();
 498         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 499         set_cpu_online(cpu, true);
 500         set_cpu_present(cpu, true);
 501         set_cpu_possible(cpu, true);
 502 }
 503
 504 void __init __weak smp_setup_processor_id(void)
 505 {
 506 }
 507
 508 void __init __weak thread_info_cache_init(void)
 509 {
 510 }
 511
 512 /*
 513  * Set up kernel memory allocators
 514  */
 515 static void __init mm_init(void)
 516 {
 517         /*
 518          * page_cgroup requires countinous pages as memmap
 519          * and it's bigger than MAX_ORDER unless SPARSEMEM.
 520          */
 521         page_cgroup_init_flatmem();
 522         mem_init();
 523         kmem_cache_init();
 524         pgtable_cache_init();
 525         vmalloc_init();
 526 }
 527
 528 asmlinkage void __init start_kernel(void)
 529 {
 530         char * command_line;
 531         extern struct kernel_param __start___param[], __stop___param[];
 532
 533         smp_setup_processor_id();
 534
 535         /*
 536          * Need to run as early as possible, to initialize the
 537          * lockdep hash:
 538          */
 539         lockdep_init();
 540         debug_objects_early_init();
 541
 542         /*
 543          * Set up the the initial canary ASAP:
 544          */
 545         boot_init_stack_canary();
 546
 547         cgroup_init_early();
 548
 549         local_irq_disable();
 550         early_boot_irqs_off();
 551         early_init_irq_lock_class();
 552
 553 /*
 554  * Interrupts are still disabled. Do necessary setups, then
 555  * enable them
 556  */
 557         lock_kernel();
 558         tick_init();
 559         boot_cpu_init();
 560         page_address_init();
 561         printk(KERN_NOTICE "%s", linux_banner);
 562         setup_arch(&command_line);
 563         mm_init_owner(&init_mm, &init_task);
 564         setup_command_line(command_line);
 565         setup_nr_cpu_ids();
 566         setup_per_cpu_areas();
 567         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 568
 569         build_all_zonelists();
 570         page_alloc_init();
 571
 572         printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
 573         parse_early_param();
 574         parse_args("Booting kernel", static_command_line, __start___param,
 575                    __stop___param - __start___param,
 576                    &unknown_bootoption);
 577         /*
 578          * These use large bootmem allocations and must precede
 579          * kmem_cache_init()
 580          */
 581         pidhash_init();
 582         vfs_caches_init_early();
 583         sort_main_extable();
 584         trap_init();
 585         mm_init();
 586         /*
 587          * Set up the scheduler prior starting any interrupts (such as the
 588          * timer interrupt). Full topology setup happens at smp_init()
 589          * time - but meanwhile we still have a functioning scheduler.
 590          */
 591         sched_init();
 592         /*
 593          * Disable preemption - early bootup scheduling is extremely
 594          * fragile until we cpu_idle() for the first time.
 595          */
 596         preempt_disable();
 597         if (!irqs_disabled()) {
 598                 printk(KERN_WARNING "start_kernel(): bug: interrupts were "
 599                                 "enabled *very* early, fixing it\n");
 600                 local_irq_disable();
 601         }
 602         rcu_init();
 603         /* init some links before init_ISA_irqs() */
 604         early_irq_init();
 605         init_IRQ();
 606         prio_tree_init();
 607         init_timers();
 608         hrtimers_init();
 609         softirq_init();
 610         timekeeping_init();
 611         time_init();
 612         profile_init();
 613         if (!irqs_disabled())
 614                 printk(KERN_CRIT "start_kernel(): bug: interrupts were "
 615                                  "enabled early\n");
 616         early_boot_irqs_on();
 617         local_irq_enable();
 618
 619         /* Interrupts are enabled now so all GFP allocations are safe. */
 620         set_gfp_allowed_mask(__GFP_BITS_MASK);
 621
 622         kmem_cache_init_late();
 623
 624         /*
 625          * HACK ALERT! This is early. We're enabling the console before
 626          * we've done PCI setups etc, and console_init() must be aware of
 627          * this. But we do want output early, in case something goes wrong.
 628          */
 629         console_init();
 630         if (panic_later)
 631                 panic(panic_later, panic_param);
 632
 633         lockdep_info();
 634
 635         /*
 636          * Need to run this when irqs are enabled, because it wants
 637          * to self-test [hard/soft]-irqs on/off lock inversion bugs
 638          * too:
 639          */
 640         locking_selftest();
 641
 642 #ifdef CONFIG_BLK_DEV_INITRD
 643         if (initrd_start && !initrd_below_start_ok &&
 644             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 645                 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
 646                     "disabling it.\n",
 647                     page_to_pfn(virt_to_page((void *)initrd_start)),
 648                     min_low_pfn);
 649                 initrd_start = 0;
 650         }
 651 #endif
 652         page_cgroup_init();
 653         enable_debug_pagealloc();
 654         kmemtrace_init();
 655         kmemleak_init();
 656         debug_objects_mem_init();
 657         idr_init_cache();
 658         setup_per_cpu_pageset();
 659         numa_policy_init();
 660         if (late_time_init)
 661                 late_time_init();
 662         sched_clock_init();
 663         calibrate_delay();
 664         pidmap_init();
 665         anon_vma_init();
 666 #ifdef CONFIG_X86
 667         if (efi_enabled)
 668                 efi_enter_virtual_mode();
 669 #endif
 670         thread_info_cache_init();
 671         cred_init();
 672         fork_init(totalram_pages);
 673         proc_caches_init();
 674         buffer_init();
 675         key_init();
 676         security_init();
 677         vfs_caches_init(totalram_pages);
 678         radix_tree_init();
 679         signals_init();
 680         /* rootfs populating might need page-writeback */
 681         page_writeback_init();
 682 #ifdef CONFIG_PROC_FS
 683         proc_root_init();
 684 #endif
 685         cgroup_init();
 686         cpuset_init();
 687         taskstats_init_early();
 688         delayacct_init();
 689
 690         check_bugs();
 691
 692         acpi_early_init(); /* before LAPIC and SMP init */
 693         sfi_init_late();
 694
 695         ftrace_init();
 696
 697         /* Do the rest non-__init'ed, we're now alive */
 698         rest_init();
 699 }
 700
 701 /* Call all constructor functions linked into the kernel. */
 702 static void __init do_ctors(void)
 703 {
 704 #ifdef CONFIG_CONSTRUCTORS
 705         ctor_fn_t *call = (ctor_fn_t *) __ctors_start;
 706
 707         for (; call < (ctor_fn_t *) __ctors_end; call++)
 708                 (*call)();
 709 #endif
 710 }
 711
 712 int initcall_debug;
 713 core_param(initcall_debug, initcall_debug, bool, 0644);
 714
 715 static char msgbuf[64];
 716 static struct boot_trace_call call;
 717 static struct boot_trace_ret ret;
 718
 719 int do_one_initcall(initcall_t fn)
 720 {
 721         int count = preempt_count();
 722         ktime_t calltime, delta, rettime;
 723
 724         if (initcall_debug) {
 725                 call.caller = task_pid_nr(current);
 726                 printk("calling  %pF @ %i\n", fn, call.caller);
 727                 calltime = ktime_get();
 728                 trace_boot_call(&call, fn);
 729                 enable_boot_trace();
 730         }
 731
 732         ret.result = fn();
 733
 734         if (initcall_debug) {
 735                 disable_boot_trace();
 736                 rettime = ktime_get();
 737                 delta = ktime_sub(rettime, calltime);
 738                 ret.duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 739                 trace_boot_ret(&ret, fn);
 740                 printk("initcall %pF returned %d after %Ld usecs\n", fn,
 741                         ret.result, ret.duration);
 742         }
 743
 744         msgbuf[0] = 0;
 745
 746         if (ret.result && ret.result != -ENODEV && initcall_debug)
 747                 sprintf(msgbuf, "error code %d ", ret.result);
 748
 749         if (preempt_count() != count) {
 750                 strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
 751                 preempt_count() = count;
 752         }
 753         if (irqs_disabled()) {
 754                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 755                 local_irq_enable();
 756         }
 757         if (msgbuf[0]) {
 758                 printk("initcall %pF returned with %s\n", fn, msgbuf);
 759         }
 760
 761         return ret.result;
 762 }
 763
 764
 765 extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
 766
 767 static void __init do_initcalls(void)
 768 {
 769         initcall_t *call;
 770
 771         for (call = __early_initcall_end; call < __initcall_end; call++)
 772                 do_one_initcall(*call);
 773
 774         /* Make sure there is no pending stuff from the initcall sequence */
 775         flush_scheduled_work();
 776 }
 777
 778 /*
 779  * Ok, the machine is now initialized. None of the devices
 780  * have been touched yet, but the CPU subsystem is up and
 781  * running, and memory and process management works.
 782  *
 783  * Now we can finally start doing some real work..
 784  */
 785 static void __init do_basic_setup(void)
 786 {
 787         rcu_init_sched(); /* needed by module_init stage. */
 788         init_workqueues();
 789         cpuset_init_smp();
 790         usermodehelper_init();
 791         init_tmpfs();
 792         driver_init();
 793         init_irq_proc();
 794         do_ctors();
 795         do_initcalls();
 796 }
 797
 798 static void __init do_pre_smp_initcalls(void)
 799 {
 800         initcall_t *call;
 801
 802         for (call = __initcall_start; call < __early_initcall_end; call++)
 803                 do_one_initcall(*call);
 804 }
 805
 806 static void run_init_process(char *init_filename)
 807 {
 808         argv_init[0] = init_filename;
 809         kernel_execve(init_filename, argv_init, envp_init);
 810 }
 811
 812 /* This is a non __init function. Force it to be noinline otherwise gcc
 813  * makes it inline to init() and it becomes part of init.text section
 814  */
 815 static noinline int init_post(void)
 816         __releases(kernel_lock)
 817 {
 818         /* need to finish all async __init code before freeing the memory */
 819         async_synchronize_full();
 820         free_initmem();
 821         unlock_kernel();
 822         mark_rodata_ro();
 823         system_state = SYSTEM_RUNNING;
 824         numa_default_policy();
 825
 826         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 827                 printk(KERN_WARNING "Warning: unable to open an initial console.\n");
 828
 829         (void) sys_dup(0);
 830         (void) sys_dup(0);
 831
 832         current->signal->flags |= SIGNAL_UNKILLABLE;
 833
 834         if (ramdisk_execute_command) {
 835                 run_init_process(ramdisk_execute_command);
 836                 printk(KERN_WARNING "Failed to execute %s\n",
 837                                 ramdisk_execute_command);
 838         }
 839
 840         /*
 841          * We try each of these until one succeeds.
 842          *
 843          * The Bourne shell can be used instead of init if we are
 844          * trying to recover a really broken machine.
 845          */
 846         if (execute_command) {
 847                 run_init_process(execute_command);
 848                 printk(KERN_WARNING "Failed to execute %s.  Attempting "
 849                                         "defaults...\n", execute_command);
 850         }
 851         run_init_process("/sbin/init");
 852         run_init_process("/etc/init");
 853         run_init_process("/bin/init");
 854         run_init_process("/bin/sh");
 855
 856         panic("No init found.  Try passing init= option to kernel.");
 857 }
 858
 859 static int __init kernel_init(void * unused)
 860 {
 861         lock_kernel();
 862
 863         /*
 864          * init can allocate pages on any node
 865          */
 866         set_mems_allowed(node_possible_map);
 867         /*
 868          * init can run on any cpu.
 869          */
 870         set_cpus_allowed_ptr(current, cpu_all_mask);
 871         /*
 872          * Tell the world that we're going to be the grim
 873          * reaper of innocent orphaned children.
 874          *
 875          * We don't want people to have to make incorrect
 876          * assumptions about where in the task array this
 877          * can be found.
 878          */
 879         init_pid_ns.child_reaper = current;
 880
 881         cad_pid = task_pid(current);
 882
 883         smp_prepare_cpus(setup_max_cpus);
 884
 885         do_pre_smp_initcalls();
 886         start_boot_trace();
 887
 888         smp_init();
 889         sched_init_smp();
 890
 891         do_basic_setup();
 892
 893         /*
 894          * check if there is an early userspace init.  If yes, let it do all
 895          * the work
 896          */
 897
 898         if (!ramdisk_execute_command)
 899                 ramdisk_execute_command = "/init";
 900
 901         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 902                 ramdisk_execute_command = NULL;
 903                 prepare_namespace();
 904         }
 905
 906         /*
 907          * Ok, we have completed the initial bootup, and
 908          * we're essentially up and running. Get rid of the
 909          * initmem segments and start the user-mode stuff..
 910          */
 911
 912         init_post();
 913         return 0;
 914 }