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
  78 #include <asm/io.h>
  79 #include <asm/bugs.h>
  80 #include <asm/setup.h>
  81 #include <asm/sections.h>
  82 #include <asm/cacheflush.h>
  83
  84 #ifdef CONFIG_X86_LOCAL_APIC
  85 #include <asm/smp.h>
  86 #endif
  87
  88 static int kernel_init(void *);
  89
  90 extern void init_IRQ(void);
  91 extern void fork_init(unsigned long);
  92 extern void mca_init(void);
  93 extern void sbus_init(void);
  94 extern void radix_tree_init(void);
  95 #ifndef CONFIG_DEBUG_RODATA
  96 static inline void mark_rodata_ro(void) { }
  97 #endif
  98
  99 #ifdef CONFIG_TC
 100 extern void tc_init(void);
 101 #endif
 102
 103 /*
 104  * Debug helper: via this flag we know that we are in 'early bootup code'
 105  * where only the boot processor is running with IRQ disabled.  This means
 106  * two things - IRQ must not be enabled before the flag is cleared and some
 107  * operations which are not allowed with IRQ disabled are allowed while the
 108  * flag is set.
 109  */
 110 bool early_boot_irqs_disabled __read_mostly;
 111
 112 enum system_states system_state __read_mostly;
 113 EXPORT_SYMBOL(system_state);
 114
 115 /*
 116  * Boot command-line arguments
 117  */
 118 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 119 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 120
 121 extern void time_init(void);
 122 /* Default late time init is NULL. archs can override this later. */
 123 void (*__initdata late_time_init)(void);
 124 extern void softirq_init(void);
 125
 126 /* Untouched command line saved by arch-specific code. */
 127 char __initdata boot_command_line[COMMAND_LINE_SIZE];
 128 /* Untouched saved command line (eg. for /proc) */
 129 char *saved_command_line;
 130 /* Command line for parameter parsing */
 131 static char *static_command_line;
 132
 133 static char *execute_command;
 134 static char *ramdisk_execute_command;
 135
 136 /*
 137  * If set, this is an indication to the drivers that reset the underlying
 138  * device before going ahead with the initialization otherwise driver might
 139  * rely on the BIOS and skip the reset operation.
 140  *
 141  * This is useful if kernel is booting in an unreliable environment.
 142  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 143  * skipped and devices will be in unknown state.
 144  */
 145 unsigned int reset_devices;
 146 EXPORT_SYMBOL(reset_devices);
 147
 148 static int __init set_reset_devices(char *str)
 149 {
 150         reset_devices = 1;
 151         return 1;
 152 }
 153
 154 __setup("reset_devices", set_reset_devices);
 155
 156 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 157 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 158 static const char *panic_later, *panic_param;
 159
 160 extern const struct obs_kernel_param __setup_start[], __setup_end[];
 161
 162 static int __init obsolete_checksetup(char *line)
 163 {
 164         const struct obs_kernel_param *p;
 165         int had_early_param = 0;
 166
 167         p = __setup_start;
 168         do {
 169                 int n = strlen(p->str);
 170                 if (parameqn(line, p->str, n)) {
 171                         if (p->early) {
 172                                 /* Already done in parse_early_param?
 173                                  * (Needs exact match on param part).
 174                                  * Keep iterating, as we can have early
 175                                  * params and __setups of same names 8( */
 176                                 if (line[n] == '\0' || line[n] == '=')
 177                                         had_early_param = 1;
 178                         } else if (!p->setup_func) {
 179                                 pr_warn("Parameter %s is obsolete, ignored\n",
 180                                         p->str);
 181                                 return 1;
 182                         } else if (p->setup_func(line + n))
 183                                 return 1;
 184                 }
 185                 p++;
 186         } while (p < __setup_end);
 187
 188         return had_early_param;
 189 }
 190
 191 /*
 192  * This should be approx 2 Bo*oMips to start (note initial shift), and will
 193  * still work even if initially too large, it will just take slightly longer
 194  */
 195 unsigned long loops_per_jiffy = (1<<12);
 196
 197 EXPORT_SYMBOL(loops_per_jiffy);
 198
 199 static int __init debug_kernel(char *str)
 200 {
 201         console_loglevel = 10;
 202         return 0;
 203 }
 204
 205 static int __init quiet_kernel(char *str)
 206 {
 207         console_loglevel = 4;
 208         return 0;
 209 }
 210
 211 early_param("debug", debug_kernel);
 212 early_param("quiet", quiet_kernel);
 213
 214 static int __init loglevel(char *str)
 215 {
 216         int newlevel;
 217
 218         /*
 219          * Only update loglevel value when a correct setting was passed,
 220          * to prevent blind crashes (when loglevel being set to 0) that
 221          * are quite hard to debug
 222          */
 223         if (get_option(&str, &newlevel)) {
 224                 console_loglevel = newlevel;
 225                 return 0;
 226         }
 227
 228         return -EINVAL;
 229 }
 230
 231 early_param("loglevel", loglevel);
 232
 233 /* Change NUL term back to "=", to make "param" the whole string. */
 234 static int __init repair_env_string(char *param, char *val, const char *unused)
 235 {
 236         if (val) {
 237                 /* param=val or param="val"? */
 238                 if (val == param+strlen(param)+1)
 239                         val[-1] = '=';
 240                 else if (val == param+strlen(param)+2) {
 241                         val[-2] = '=';
 242                         memmove(val-1, val, strlen(val)+1);
 243                         val--;
 244                 } else
 245                         BUG();
 246         }
 247         return 0;
 248 }
 249
 250 /*
 251  * Unknown boot options get handed to init, unless they look like
 252  * unused parameters (modprobe will find them in /proc/cmdline).
 253  */
 254 static int __init unknown_bootoption(char *param, char *val, const char *unused)
 255 {
 256         repair_env_string(param, val, unused);
 257
 258         /* Handle obsolete-style parameters */
 259         if (obsolete_checksetup(param))
 260                 return 0;
 261
 262         /* Unused module parameter. */
 263         if (strchr(param, '.') && (!val || strchr(param, '.') < val))
 264                 return 0;
 265
 266         if (panic_later)
 267                 return 0;
 268
 269         if (val) {
 270                 /* Environment option */
 271                 unsigned int i;
 272                 for (i = 0; envp_init[i]; i++) {
 273                         if (i == MAX_INIT_ENVS) {
 274                                 panic_later = "Too many boot env vars at `%s'";
 275                                 panic_param = param;
 276                         }
 277                         if (!strncmp(param, envp_init[i], val - param))
 278                                 break;
 279                 }
 280                 envp_init[i] = param;
 281         } else {
 282                 /* Command line option */
 283                 unsigned int i;
 284                 for (i = 0; argv_init[i]; i++) {
 285                         if (i == MAX_INIT_ARGS) {
 286                                 panic_later = "Too many boot init vars at `%s'";
 287                                 panic_param = param;
 288                         }
 289                 }
 290                 argv_init[i] = param;
 291         }
 292         return 0;
 293 }
 294
 295 static int __init init_setup(char *str)
 296 {
 297         unsigned int i;
 298
 299         execute_command = str;
 300         /*
 301          * In case LILO is going to boot us with default command line,
 302          * it prepends "auto" before the whole cmdline which makes
 303          * the shell think it should execute a script with such name.
 304          * So we ignore all arguments entered _before_ init=... [MJ]
 305          */
 306         for (i = 1; i < MAX_INIT_ARGS; i++)
 307                 argv_init[i] = NULL;
 308         return 1;
 309 }
 310 __setup("init=", init_setup);
 311
 312 static int __init rdinit_setup(char *str)
 313 {
 314         unsigned int i;
 315
 316         ramdisk_execute_command = str;
 317         /* See "auto" comment in init_setup */
 318         for (i = 1; i < MAX_INIT_ARGS; i++)
 319                 argv_init[i] = NULL;
 320         return 1;
 321 }
 322 __setup("rdinit=", rdinit_setup);
 323
 324 #ifndef CONFIG_SMP
 325 static const unsigned int setup_max_cpus = NR_CPUS;
 326 #ifdef CONFIG_X86_LOCAL_APIC
 327 static void __init smp_init(void)
 328 {
 329         APIC_init_uniprocessor();
 330 }
 331 #else
 332 #define smp_init()      do { } while (0)
 333 #endif
 334
 335 static inline void setup_nr_cpu_ids(void) { }
 336 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 337 #endif
 338
 339 /*
 340  * We need to store the untouched command line for future reference.
 341  * We also need to store the touched command line since the parameter
 342  * parsing is performed in place, and we should allow a component to
 343  * store reference of name/value for future reference.
 344  */
 345 static void __init setup_command_line(char *command_line)
 346 {
 347         saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 348         static_command_line = alloc_bootmem(strlen (command_line)+1);
 349         strcpy (saved_command_line, boot_command_line);
 350         strcpy (static_command_line, command_line);
 351 }
 352
 353 /*
 354  * We need to finalize in a non-__init function or else race conditions
 355  * between the root thread and the init thread may cause start_kernel to
 356  * be reaped by free_initmem before the root thread has proceeded to
 357  * cpu_idle.
 358  *
 359  * gcc-3.4 accidentally inlines this function, so use noinline.
 360  */
 361
 362 static __initdata DECLARE_COMPLETION(kthreadd_done);
 363
 364 static noinline void __init_refok rest_init(void)
 365 {
 366         int pid;
 367
 368         rcu_scheduler_starting();
 369         /*
 370          * We need to spawn init first so that it obtains pid 1, however
 371          * the init task will end up wanting to create kthreads, which, if
 372          * we schedule it before we create kthreadd, will OOPS.
 373          */
 374         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 375         numa_default_policy();
 376         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 377         rcu_read_lock();
 378         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 379         rcu_read_unlock();
 380         complete(&kthreadd_done);
 381
 382         /*
 383          * The boot idle thread must execute schedule()
 384          * at least once to get things moving:
 385          */
 386         init_idle_bootup_task(current);
 387         schedule_preempt_disabled();
 388         /* Call into cpu_idle with preempt disabled */
 389         cpu_startup_entry(CPUHP_ONLINE);
 390 }
 391
 392 /* Check for early params. */
 393 static int __init do_early_param(char *param, char *val, const char *unused)
 394 {
 395         const struct obs_kernel_param *p;
 396
 397         for (p = __setup_start; p < __setup_end; p++) {
 398                 if ((p->early && parameq(param, p->str)) ||
 399                     (strcmp(param, "console") == 0 &&
 400                      strcmp(p->str, "earlycon") == 0)
 401                 ) {
 402                         if (p->setup_func(val) != 0)
 403                                 pr_warn("Malformed early option '%s'\n", param);
 404                 }
 405         }
 406         /* We accept everything at this stage. */
 407         return 0;
 408 }
 409
 410 void __init parse_early_options(char *cmdline)
 411 {
 412         parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
 413 }
 414
 415 /* Arch code calls this early on, or if not, just before other parsing. */
 416 void __init parse_early_param(void)
 417 {
 418         static __initdata int done = 0;
 419         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 420
 421         if (done)
 422                 return;
 423
 424         /* All fall through to do_early_param. */
 425         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 426         parse_early_options(tmp_cmdline);
 427         done = 1;
 428 }
 429
 430 /*
 431  *      Activate the first processor.
 432  */
 433
 434 static void __init boot_cpu_init(void)
 435 {
 436         int cpu = smp_processor_id();
 437         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 438         set_cpu_online(cpu, true);
 439         set_cpu_active(cpu, true);
 440         set_cpu_present(cpu, true);
 441         set_cpu_possible(cpu, true);
 442 }
 443
 444 void __init __weak smp_setup_processor_id(void)
 445 {
 446 }
 447
 448 # if THREAD_SIZE >= PAGE_SIZE
 449 void __init __weak thread_info_cache_init(void)
 450 {
 451 }
 452 #endif
 453
 454 /*
 455  * Set up kernel memory allocators
 456  */
 457 static void __init mm_init(void)
 458 {
 459         /*
 460          * page_cgroup requires contiguous pages,
 461          * bigger than MAX_ORDER unless SPARSEMEM.
 462          */
 463         page_cgroup_init_flatmem();
 464         mem_init();
 465         kmem_cache_init();
 466         percpu_init_late();
 467         pgtable_cache_init();
 468         vmalloc_init();
 469 }
 470
 471 asmlinkage void __init start_kernel(void)
 472 {
 473         char * command_line;
 474         extern const struct kernel_param __start___param[], __stop___param[];
 475
 476         /*
 477          * Need to run as early as possible, to initialize the
 478          * lockdep hash:
 479          */
 480         lockdep_init();
 481         smp_setup_processor_id();
 482         debug_objects_early_init();
 483
 484         /*
 485          * Set up the the initial canary ASAP:
 486          */
 487         boot_init_stack_canary();
 488
 489         cgroup_init_early();
 490
 491         local_irq_disable();
 492         early_boot_irqs_disabled = true;
 493
 494 /*
 495  * Interrupts are still disabled. Do necessary setups, then
 496  * enable them
 497  */
 498         boot_cpu_init();
 499         page_address_init();
 500         pr_notice("%s", linux_banner);
 501         setup_arch(&command_line);
 502         mm_init_owner(&init_mm, &init_task);
 503         mm_init_cpumask(&init_mm);
 504         setup_command_line(command_line);
 505         setup_nr_cpu_ids();
 506         setup_per_cpu_areas();
 507         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 508
 509         build_all_zonelists(NULL, NULL);
 510         page_alloc_init();
 511
 512         pr_notice("Kernel command line: %s\n", boot_command_line);
 513         parse_early_param();
 514         parse_args("Booting kernel", static_command_line, __start___param,
 515                    __stop___param - __start___param,
 516                    -1, -1, &unknown_bootoption);
 517
 518         jump_label_init();
 519
 520         /*
 521          * These use large bootmem allocations and must precede
 522          * kmem_cache_init()
 523          */
 524         setup_log_buf(0);
 525         pidhash_init();
 526         vfs_caches_init_early();
 527         sort_main_extable();
 528         trap_init();
 529         mm_init();
 530
 531         /*
 532          * Set up the scheduler prior starting any interrupts (such as the
 533          * timer interrupt). Full topology setup happens at smp_init()
 534          * time - but meanwhile we still have a functioning scheduler.
 535          */
 536         sched_init();
 537         /*
 538          * Disable preemption - early bootup scheduling is extremely
 539          * fragile until we cpu_idle() for the first time.
 540          */
 541         preempt_disable();
 542         if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
 543                 local_irq_disable();
 544         idr_init_cache();
 545         rcu_init();
 546         tick_nohz_init();
 547         radix_tree_init();
 548         /* init some links before init_ISA_irqs() */
 549         early_irq_init();
 550         init_IRQ();
 551         tick_init();
 552         init_timers();
 553         hrtimers_init();
 554         softirq_init();
 555         timekeeping_init();
 556         time_init();
 557         perf_event_init();
 558         profile_init();
 559         call_function_init();
 560         WARN(!irqs_disabled(), "Interrupts were enabled early\n");
 561         early_boot_irqs_disabled = false;
 562         local_irq_enable();
 563
 564         kmem_cache_init_late();
 565
 566         /*
 567          * HACK ALERT! This is early. We're enabling the console before
 568          * we've done PCI setups etc, and console_init() must be aware of
 569          * this. But we do want output early, in case something goes wrong.
 570          */
 571         console_init();
 572         if (panic_later)
 573                 panic(panic_later, panic_param);
 574
 575         lockdep_info();
 576
 577         /*
 578          * Need to run this when irqs are enabled, because it wants
 579          * to self-test [hard/soft]-irqs on/off lock inversion bugs
 580          * too:
 581          */
 582         locking_selftest();
 583
 584 #ifdef CONFIG_BLK_DEV_INITRD
 585         if (initrd_start && !initrd_below_start_ok &&
 586             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 587                 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
 588                     page_to_pfn(virt_to_page((void *)initrd_start)),
 589                     min_low_pfn);
 590                 initrd_start = 0;
 591         }
 592 #endif
 593         page_cgroup_init();
 594         debug_objects_mem_init();
 595         kmemleak_init();
 596         setup_per_cpu_pageset();
 597         numa_policy_init();
 598         if (late_time_init)
 599                 late_time_init();
 600         sched_clock_init();
 601         calibrate_delay();
 602         pidmap_init();
 603         anon_vma_init();
 604 #ifdef CONFIG_X86
 605         if (efi_enabled(EFI_RUNTIME_SERVICES))
 606                 efi_enter_virtual_mode();
 607 #endif
 608         thread_info_cache_init();
 609         cred_init();
 610         fork_init(totalram_pages);
 611         proc_caches_init();
 612         buffer_init();
 613         key_init();
 614         security_init();
 615         dbg_late_init();
 616         vfs_caches_init(totalram_pages);
 617         signals_init();
 618         /* rootfs populating might need page-writeback */
 619         page_writeback_init();
 620 #ifdef CONFIG_PROC_FS
 621         proc_root_init();
 622 #endif
 623         cgroup_init();
 624         cpuset_init();
 625         taskstats_init_early();
 626         delayacct_init();
 627
 628         check_bugs();
 629
 630         acpi_early_init(); /* before LAPIC and SMP init */
 631         sfi_init_late();
 632
 633         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 634                 efi_late_init();
 635                 efi_free_boot_services();
 636         }
 637
 638         ftrace_init();
 639
 640         /* Do the rest non-__init'ed, we're now alive */
 641         rest_init();
 642 }
 643
 644 /* Call all constructor functions linked into the kernel. */
 645 static void __init do_ctors(void)
 646 {
 647 #ifdef CONFIG_CONSTRUCTORS
 648         ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
 649
 650         for (; fn < (ctor_fn_t *) __ctors_end; fn++)
 651                 (*fn)();
 652 #endif
 653 }
 654
 655 bool initcall_debug;
 656 core_param(initcall_debug, initcall_debug, bool, 0644);
 657
 658 static char msgbuf[64];
 659
 660 static int __init_or_module do_one_initcall_debug(initcall_t fn)
 661 {
 662         ktime_t calltime, delta, rettime;
 663         unsigned long long duration;
 664         int ret;
 665
 666         pr_debug("calling  %pF @ %i\n", fn, task_pid_nr(current));
 667         calltime = ktime_get();
 668         ret = fn();
 669         rettime = ktime_get();
 670         delta = ktime_sub(rettime, calltime);
 671         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 672         pr_debug("initcall %pF returned %d after %lld usecs\n",
 673                  fn, ret, duration);
 674
 675         return ret;
 676 }
 677
 678 int __init_or_module do_one_initcall(initcall_t fn)
 679 {
 680         int count = preempt_count();
 681         int ret;
 682
 683         if (initcall_debug)
 684                 ret = do_one_initcall_debug(fn);
 685         else
 686                 ret = fn();
 687
 688         msgbuf[0] = 0;
 689
 690         if (preempt_count() != count) {
 691                 sprintf(msgbuf, "preemption imbalance ");
 692                 preempt_count() = count;
 693         }
 694         if (irqs_disabled()) {
 695                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 696                 local_irq_enable();
 697         }
 698         WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
 699
 700         return ret;
 701 }
 702
 703
 704 extern initcall_t __initcall_start[];
 705 extern initcall_t __initcall0_start[];
 706 extern initcall_t __initcall1_start[];
 707 extern initcall_t __initcall2_start[];
 708 extern initcall_t __initcall3_start[];
 709 extern initcall_t __initcall4_start[];
 710 extern initcall_t __initcall5_start[];
 711 extern initcall_t __initcall6_start[];
 712 extern initcall_t __initcall7_start[];
 713 extern initcall_t __initcall_end[];
 714
 715 static initcall_t *initcall_levels[] __initdata = {
 716         __initcall0_start,
 717         __initcall1_start,
 718         __initcall2_start,
 719         __initcall3_start,
 720         __initcall4_start,
 721         __initcall5_start,
 722         __initcall6_start,
 723         __initcall7_start,
 724         __initcall_end,
 725 };
 726
 727 /* Keep these in sync with initcalls in include/linux/init.h */
 728 static char *initcall_level_names[] __initdata = {
 729         "early",
 730         "core",
 731         "postcore",
 732         "arch",
 733         "subsys",
 734         "fs",
 735         "device",
 736         "late",
 737 };
 738
 739 static void __init do_initcall_level(int level)
 740 {
 741         extern const struct kernel_param __start___param[], __stop___param[];
 742         initcall_t *fn;
 743
 744         strcpy(static_command_line, saved_command_line);
 745         parse_args(initcall_level_names[level],
 746                    static_command_line, __start___param,
 747                    __stop___param - __start___param,
 748                    level, level,
 749                    &repair_env_string);
 750
 751         for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
 752                 do_one_initcall(*fn);
 753 }
 754
 755 static void __init do_initcalls(void)
 756 {
 757         int level;
 758
 759         for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
 760                 do_initcall_level(level);
 761 }
 762
 763 /*
 764  * Ok, the machine is now initialized. None of the devices
 765  * have been touched yet, but the CPU subsystem is up and
 766  * running, and memory and process management works.
 767  *
 768  * Now we can finally start doing some real work..
 769  */
 770 static void __init do_basic_setup(void)
 771 {
 772         cpuset_init_smp();
 773         usermodehelper_init();
 774         shmem_init();
 775         driver_init();
 776         init_irq_proc();
 777         do_ctors();
 778         usermodehelper_enable();
 779         do_initcalls();
 780 }
 781
 782 static void __init do_pre_smp_initcalls(void)
 783 {
 784         initcall_t *fn;
 785
 786         for (fn = __initcall_start; fn < __initcall0_start; fn++)
 787                 do_one_initcall(*fn);
 788 }
 789
 790 /*
 791  * This function requests modules which should be loaded by default and is
 792  * called twice right after initrd is mounted and right before init is
 793  * exec'd.  If such modules are on either initrd or rootfs, they will be
 794  * loaded before control is passed to userland.
 795  */
 796 void __init load_default_modules(void)
 797 {
 798         load_default_elevator_module();
 799 }
 800
 801 static int run_init_process(const char *init_filename)
 802 {
 803         argv_init[0] = init_filename;
 804         return do_execve(init_filename,
 805                 (const char __user *const __user *)argv_init,
 806                 (const char __user *const __user *)envp_init);
 807 }
 808
 809 static noinline void __init kernel_init_freeable(void);
 810
 811 static int __ref kernel_init(void *unused)
 812 {
 813         kernel_init_freeable();
 814         /* need to finish all async __init code before freeing the memory */
 815         async_synchronize_full();
 816         free_initmem();
 817         mark_rodata_ro();
 818         system_state = SYSTEM_RUNNING;
 819         numa_default_policy();
 820
 821         flush_delayed_fput();
 822
 823         if (ramdisk_execute_command) {
 824                 if (!run_init_process(ramdisk_execute_command))
 825                         return 0;
 826                 pr_err("Failed to execute %s\n", ramdisk_execute_command);
 827         }
 828
 829         /*
 830          * We try each of these until one succeeds.
 831          *
 832          * The Bourne shell can be used instead of init if we are
 833          * trying to recover a really broken machine.
 834          */
 835         if (execute_command) {
 836                 if (!run_init_process(execute_command))
 837                         return 0;
 838                 pr_err("Failed to execute %s.  Attempting defaults...\n",
 839                         execute_command);
 840         }
 841         if (!run_init_process("/sbin/init") ||
 842             !run_init_process("/etc/init") ||
 843             !run_init_process("/bin/init") ||
 844             !run_init_process("/bin/sh"))
 845                 return 0;
 846
 847         panic("No init found.  Try passing init= option to kernel. "
 848               "See Linux Documentation/init.txt for guidance.");
 849 }
 850
 851 static noinline void __init kernel_init_freeable(void)
 852 {
 853         /*
 854          * Wait until kthreadd is all set-up.
 855          */
 856         wait_for_completion(&kthreadd_done);
 857
 858         /* Now the scheduler is fully set up and can do blocking allocations */
 859         gfp_allowed_mask = __GFP_BITS_MASK;
 860
 861         /*
 862          * init can allocate pages on any node
 863          */
 864         set_mems_allowed(node_states[N_MEMORY]);
 865         /*
 866          * init can run on any cpu.
 867          */
 868         set_cpus_allowed_ptr(current, cpu_all_mask);
 869
 870         cad_pid = task_pid(current);
 871
 872         smp_prepare_cpus(setup_max_cpus);
 873
 874         do_pre_smp_initcalls();
 875         lockup_detector_init();
 876
 877         smp_init();
 878         sched_init_smp();
 879
 880         do_basic_setup();
 881
 882         /* Open the /dev/console on the rootfs, this should never fail */
 883         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 884                 pr_err("Warning: unable to open an initial console.\n");
 885
 886         (void) sys_dup(0);
 887         (void) sys_dup(0);
 888         /*
 889          * check if there is an early userspace init.  If yes, let it do all
 890          * the work
 891          */
 892
 893         if (!ramdisk_execute_command)
 894                 ramdisk_execute_command = "/init";
 895
 896         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 897                 ramdisk_execute_command = NULL;
 898                 prepare_namespace();
 899         }
 900
 901         /*
 902          * Ok, we have completed the initial bootup, and
 903          * we're essentially up and running. Get rid of the
 904          * initmem segments and start the user-mode stuff..
 905          */
 906
 907         /* rootfs is available now, try loading default modules */
 908         load_default_modules();
 909 }