init/main.c

   1 /*
   2  *  linux/init/main.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  GK 2/5/95  -  Changed to support mounting root fs via NFS
   7  *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
   8  *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
   9  *  Simplified starting of init:  Michael A. Griffith <grif@acm.org>
  10  */
  11
  12 #define DEBUG           /* Enable initcall_debug */
  13
  14 #include <linux/types.h>
  15 #include <linux/module.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/kernel.h>
  18 #include <linux/syscalls.h>
  19 #include <linux/stackprotector.h>
  20 #include <linux/string.h>
  21 #include <linux/ctype.h>
  22 #include <linux/delay.h>
  23 #include <linux/ioport.h>
  24 #include <linux/init.h>
  25 #include <linux/initrd.h>
  26 #include <linux/bootmem.h>
  27 #include <linux/acpi.h>
  28 #include <linux/tty.h>
  29 #include <linux/percpu.h>
  30 #include <linux/kmod.h>
  31 #include <linux/vmalloc.h>
  32 #include <linux/kernel_stat.h>
  33 #include <linux/start_kernel.h>
  34 #include <linux/security.h>
  35 #include <linux/smp.h>
  36 #include <linux/profile.h>
  37 #include <linux/rcupdate.h>
  38 #include <linux/moduleparam.h>
  39 #include <linux/kallsyms.h>
  40 #include <linux/writeback.h>
  41 #include <linux/cpu.h>
  42 #include <linux/cpuset.h>
  43 #include <linux/cgroup.h>
  44 #include <linux/efi.h>
  45 #include <linux/tick.h>
  46 #include <linux/interrupt.h>
  47 #include <linux/taskstats_kern.h>
  48 #include <linux/delayacct.h>
  49 #include <linux/unistd.h>
  50 #include <linux/rmap.h>
  51 #include <linux/mempolicy.h>
  52 #include <linux/key.h>
  53 #include <linux/buffer_head.h>
  54 #include <linux/page_cgroup.h>
  55 #include <linux/debug_locks.h>
  56 #include <linux/debugobjects.h>
  57 #include <linux/lockdep.h>
  58 #include <linux/kmemleak.h>
  59 #include <linux/pid_namespace.h>
  60 #include <linux/device.h>
  61 #include <linux/kthread.h>
  62 #include <linux/sched.h>
  63 #include <linux/signal.h>
  64 #include <linux/idr.h>
  65 #include <linux/kgdb.h>
  66 #include <linux/ftrace.h>
  67 #include <linux/async.h>
  68 #include <linux/kmemcheck.h>
  69 #include <linux/sfi.h>
  70 #include <linux/shmem_fs.h>
  71 #include <linux/slab.h>
  72 #include <linux/perf_event.h>
  73 #include <linux/file.h>
  74 #include <linux/ptrace.h>
  75 #include <linux/blkdev.h>
  76 #include <linux/elevator.h>
  77 #include <linux/sched_clock.h>
  78 #include <linux/context_tracking.h>
  79
  80 #include <asm/io.h>
  81 #include <asm/bugs.h>
  82 #include <asm/setup.h>
  83 #include <asm/sections.h>
  84 #include <asm/cacheflush.h>
  85
  86 #ifdef CONFIG_X86_LOCAL_APIC
  87 #include <asm/smp.h>
  88 #endif
  89
  90 static int kernel_init(void *);
  91
  92 extern void init_IRQ(void);
  93 extern void fork_init(unsigned long);
  94 extern void mca_init(void);
  95 extern void sbus_init(void);
  96 extern void radix_tree_init(void);
  97 #ifndef CONFIG_DEBUG_RODATA
  98 static inline void mark_rodata_ro(void) { }
  99 #endif
 100
 101 #ifdef CONFIG_TC
 102 extern void tc_init(void);
 103 #endif
 104
 105 /*
 106  * Debug helper: via this flag we know that we are in 'early bootup code'
 107  * where only the boot processor is running with IRQ disabled.  This means
 108  * two things - IRQ must not be enabled before the flag is cleared and some
 109  * operations which are not allowed with IRQ disabled are allowed while the
 110  * flag is set.
 111  */
 112 bool early_boot_irqs_disabled __read_mostly;
 113
 114 enum system_states system_state __read_mostly;
 115 EXPORT_SYMBOL(system_state);
 116
 117 /*
 118  * Boot command-line arguments
 119  */
 120 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 121 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 122
 123 extern void time_init(void);
 124 /* Default late time init is NULL. archs can override this later. */
 125 void (*__initdata late_time_init)(void);
 126 extern void softirq_init(void);
 127
 128 /* Untouched command line saved by arch-specific code. */
 129 char __initdata boot_command_line[COMMAND_LINE_SIZE];
 130 /* Untouched saved command line (eg. for /proc) */
 131 char *saved_command_line;
 132 /* Command line for parameter parsing */
 133 static char *static_command_line;
 134
 135 static char *execute_command;
 136 static char *ramdisk_execute_command;
 137
 138 /*
 139  * If set, this is an indication to the drivers that reset the underlying
 140  * device before going ahead with the initialization otherwise driver might
 141  * rely on the BIOS and skip the reset operation.
 142  *
 143  * This is useful if kernel is booting in an unreliable environment.
 144  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 145  * skipped and devices will be in unknown state.
 146  */
 147 unsigned int reset_devices;
 148 EXPORT_SYMBOL(reset_devices);
 149
 150 static int __init set_reset_devices(char *str)
 151 {
 152         reset_devices = 1;
 153         return 1;
 154 }
 155
 156 __setup("reset_devices", set_reset_devices);
 157
 158 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 159 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 160 static const char *panic_later, *panic_param;
 161
 162 extern const struct obs_kernel_param __setup_start[], __setup_end[];
 163
 164 static int __init obsolete_checksetup(char *line)
 165 {
 166         const struct obs_kernel_param *p;
 167         int had_early_param = 0;
 168
 169         p = __setup_start;
 170         do {
 171                 int n = strlen(p->str);
 172                 if (parameqn(line, p->str, n)) {
 173                         if (p->early) {
 174                                 /* Already done in parse_early_param?
 175                                  * (Needs exact match on param part).
 176                                  * Keep iterating, as we can have early
 177                                  * params and __setups of same names 8( */
 178                                 if (line[n] == '\0' || line[n] == '=')
 179                                         had_early_param = 1;
 180                         } else if (!p->setup_func) {
 181                                 pr_warn("Parameter %s is obsolete, ignored\n",
 182                                         p->str);
 183                                 return 1;
 184                         } else if (p->setup_func(line + n))
 185                                 return 1;
 186                 }
 187                 p++;
 188         } while (p < __setup_end);
 189
 190         return had_early_param;
 191 }
 192
 193 /*
 194  * This should be approx 2 Bo*oMips to start (note initial shift), and will
 195  * still work even if initially too large, it will just take slightly longer
 196  */
 197 unsigned long loops_per_jiffy = (1<<12);
 198
 199 EXPORT_SYMBOL(loops_per_jiffy);
 200
 201 static int __init debug_kernel(char *str)
 202 {
 203         console_loglevel = 10;
 204         return 0;
 205 }
 206
 207 static int __init quiet_kernel(char *str)
 208 {
 209         console_loglevel = 4;
 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, const char *unused)
 237 {
 238         if (val) {
 239                 /* param=val or param="val"? */
 240                 if (val == param+strlen(param)+1)
 241                         val[-1] = '=';
 242                 else if (val == param+strlen(param)+2) {
 243                         val[-2] = '=';
 244                         memmove(val-1, val, strlen(val)+1);
 245                         val--;
 246                 } else
 247                         BUG();
 248         }
 249         return 0;
 250 }
 251
 252 /*
 253  * Unknown boot options get handed to init, unless they look like
 254  * unused parameters (modprobe will find them in /proc/cmdline).
 255  */
 256 static int __init unknown_bootoption(char *param, char *val, const char *unused)
 257 {
 258         repair_env_string(param, val, unused);
 259
 260         /* Handle obsolete-style parameters */
 261         if (obsolete_checksetup(param))
 262                 return 0;
 263
 264         /* Unused module parameter. */
 265         if (strchr(param, '.') && (!val || strchr(param, '.') < val))
 266                 return 0;
 267
 268         if (panic_later)
 269                 return 0;
 270
 271         if (val) {
 272                 /* Environment option */
 273                 unsigned int i;
 274                 for (i = 0; envp_init[i]; i++) {
 275                         if (i == MAX_INIT_ENVS) {
 276                                 panic_later = "Too many boot env vars at `%s'";
 277                                 panic_param = param;
 278                         }
 279                         if (!strncmp(param, envp_init[i], val - param))
 280                                 break;
 281                 }
 282                 envp_init[i] = param;
 283         } else {
 284                 /* Command line option */
 285                 unsigned int i;
 286                 for (i = 0; argv_init[i]; i++) {
 287                         if (i == MAX_INIT_ARGS) {
 288                                 panic_later = "Too many boot init vars at `%s'";
 289                                 panic_param = param;
 290                         }
 291                 }
 292                 argv_init[i] = param;
 293         }
 294         return 0;
 295 }
 296
 297 static int __init init_setup(char *str)
 298 {
 299         unsigned int i;
 300
 301         execute_command = str;
 302         /*
 303          * In case LILO is going to boot us with default command line,
 304          * it prepends "auto" before the whole cmdline which makes
 305          * the shell think it should execute a script with such name.
 306          * So we ignore all arguments entered _before_ init=... [MJ]
 307          */
 308         for (i = 1; i < MAX_INIT_ARGS; i++)
 309                 argv_init[i] = NULL;
 310         return 1;
 311 }
 312 __setup("init=", init_setup);
 313
 314 static int __init rdinit_setup(char *str)
 315 {
 316         unsigned int i;
 317
 318         ramdisk_execute_command = str;
 319         /* See "auto" comment in init_setup */
 320         for (i = 1; i < MAX_INIT_ARGS; i++)
 321                 argv_init[i] = NULL;
 322         return 1;
 323 }
 324 __setup("rdinit=", rdinit_setup);
 325
 326 #ifndef CONFIG_SMP
 327 static const unsigned int setup_max_cpus = NR_CPUS;
 328 #ifdef CONFIG_X86_LOCAL_APIC
 329 static void __init smp_init(void)
 330 {
 331         APIC_init_uniprocessor();
 332 }
 333 #else
 334 #define smp_init()      do { } while (0)
 335 #endif
 336
 337 static inline void setup_nr_cpu_ids(void) { }
 338 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 339 #endif
 340
 341 /*
 342  * We need to store the untouched command line for future reference.
 343  * We also need to store the touched command line since the parameter
 344  * parsing is performed in place, and we should allow a component to
 345  * store reference of name/value for future reference.
 346  */
 347 static void __init setup_command_line(char *command_line)
 348 {
 349         saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 350         static_command_line = alloc_bootmem(strlen (command_line)+1);
 351         strcpy (saved_command_line, boot_command_line);
 352         strcpy (static_command_line, command_line);
 353 }
 354
 355 /*
 356  * We need to finalize in a non-__init function or else race conditions
 357  * between the root thread and the init thread may cause start_kernel to
 358  * be reaped by free_initmem before the root thread has proceeded to
 359  * cpu_idle.
 360  *
 361  * gcc-3.4 accidentally inlines this function, so use noinline.
 362  */
 363
 364 static __initdata DECLARE_COMPLETION(kthreadd_done);
 365
 366 static noinline void __init_refok rest_init(void)
 367 {
 368         int pid;
 369
 370         rcu_scheduler_starting();
 371         /*
 372          * We need to spawn init first so that it obtains pid 1, however
 373          * the init task will end up wanting to create kthreads, which, if
 374          * we schedule it before we create kthreadd, will OOPS.
 375          */
 376         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 377         numa_default_policy();
 378         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 379         rcu_read_lock();
 380         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 381         rcu_read_unlock();
 382         complete(&kthreadd_done);
 383
 384         /*
 385          * The boot idle thread must execute schedule()
 386          * at least once to get things moving:
 387          */
 388         init_idle_bootup_task(current);
 389         schedule_preempt_disabled();
 390         /* Call into cpu_idle with preempt disabled */
 391         cpu_startup_entry(CPUHP_ONLINE);
 392 }
 393
 394 /* Check for early params. */
 395 static int __init do_early_param(char *param, char *val, const char *unused)
 396 {
 397         const struct obs_kernel_param *p;
 398
 399         for (p = __setup_start; p < __setup_end; p++) {
 400                 if ((p->early && parameq(param, p->str)) ||
 401                     (strcmp(param, "console") == 0 &&
 402                      strcmp(p->str, "earlycon") == 0)
 403                 ) {
 404                         if (p->setup_func(val) != 0)
 405                                 pr_warn("Malformed early option '%s'\n", param);
 406                 }
 407         }
 408         /* We accept everything at this stage. */
 409         return 0;
 410 }
 411
 412 void __init parse_early_options(char *cmdline)
 413 {
 414         parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
 415 }
 416
 417 /* Arch code calls this early on, or if not, just before other parsing. */
 418 void __init parse_early_param(void)
 419 {
 420         static __initdata int done = 0;
 421         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 422
 423         if (done)
 424                 return;
 425
 426         /* All fall through to do_early_param. */
 427         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 428         parse_early_options(tmp_cmdline);
 429         done = 1;
 430 }
 431
 432 /*
 433  *      Activate the first processor.
 434  */
 435
 436 static void __init boot_cpu_init(void)
 437 {
 438         int cpu = smp_processor_id();
 439         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 440         set_cpu_online(cpu, true);
 441         set_cpu_active(cpu, true);
 442         set_cpu_present(cpu, true);
 443         set_cpu_possible(cpu, true);
 444 }
 445
 446 void __init __weak smp_setup_processor_id(void)
 447 {
 448 }
 449
 450 # if THREAD_SIZE >= PAGE_SIZE
 451 void __init __weak thread_info_cache_init(void)
 452 {
 453 }
 454 #endif
 455
 456 /*
 457  * Set up kernel memory allocators
 458  */
 459 static void __init mm_init(void)
 460 {
 461         /*
 462          * page_cgroup requires contiguous pages,
 463          * bigger than MAX_ORDER unless SPARSEMEM.
 464          */
 465         page_cgroup_init_flatmem();
 466         mem_init();
 467         kmem_cache_init();
 468         percpu_init_late();
 469         pgtable_cache_init();
 470         vmalloc_init();
 471 }
 472
 473 asmlinkage void __init start_kernel(void)
 474 {
 475         char * command_line;
 476         extern const struct kernel_param __start___param[], __stop___param[];
 477
 478         /*
 479          * Need to run as early as possible, to initialize the
 480          * lockdep hash:
 481          */
 482         lockdep_init();
 483         smp_setup_processor_id();
 484         debug_objects_early_init();
 485
 486         /*
 487          * Set up the the initial canary ASAP:
 488          */
 489         boot_init_stack_canary();
 490
 491         cgroup_init_early();
 492
 493         local_irq_disable();
 494         early_boot_irqs_disabled = true;
 495
 496 /*
 497  * Interrupts are still disabled. Do necessary setups, then
 498  * enable them
 499  */
 500         boot_cpu_init();
 501         page_address_init();
 502         pr_notice("%s", linux_banner);
 503         setup_arch(&command_line);
 504         mm_init_owner(&init_mm, &init_task);
 505         mm_init_cpumask(&init_mm);
 506         setup_command_line(command_line);
 507         setup_nr_cpu_ids();
 508         setup_per_cpu_areas();
 509         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 510
 511         build_all_zonelists(NULL, NULL);
 512         page_alloc_init();
 513
 514         pr_notice("Kernel command line: %s\n", boot_command_line);
 515         parse_early_param();
 516         parse_args("Booting kernel", static_command_line, __start___param,
 517                    __stop___param - __start___param,
 518                    -1, -1, &unknown_bootoption);
 519
 520         jump_label_init();
 521
 522         /*
 523          * These use large bootmem allocations and must precede
 524          * kmem_cache_init()
 525          */
 526         setup_log_buf(0);
 527         pidhash_init();
 528         vfs_caches_init_early();
 529         sort_main_extable();
 530         trap_init();
 531         mm_init();
 532
 533         /*
 534          * Set up the scheduler prior starting any interrupts (such as the
 535          * timer interrupt). Full topology setup happens at smp_init()
 536          * time - but meanwhile we still have a functioning scheduler.
 537          */
 538         sched_init();
 539         /*
 540          * Disable preemption - early bootup scheduling is extremely
 541          * fragile until we cpu_idle() for the first time.
 542          */
 543         preempt_disable();
 544         if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
 545                 local_irq_disable();
 546         idr_init_cache();
 547         rcu_init();
 548         tick_nohz_init();
 549         context_tracking_init();
 550         radix_tree_init();
 551         /* init some links before init_ISA_irqs() */
 552         early_irq_init();
 553         init_IRQ();
 554         tick_init();
 555         init_timers();
 556         hrtimers_init();
 557         softirq_init();
 558         timekeeping_init();
 559         time_init();
 560         sched_clock_postinit();
 561         perf_event_init();
 562         profile_init();
 563         call_function_init();
 564         WARN(!irqs_disabled(), "Interrupts were enabled early\n");
 565         early_boot_irqs_disabled = false;
 566         local_irq_enable();
 567
 568         kmem_cache_init_late();
 569
 570         /*
 571          * HACK ALERT! This is early. We're enabling the console before
 572          * we've done PCI setups etc, and console_init() must be aware of
 573          * this. But we do want output early, in case something goes wrong.
 574          */
 575         console_init();
 576         if (panic_later)
 577                 panic(panic_later, panic_param);
 578
 579         lockdep_info();
 580
 581         /*
 582          * Need to run this when irqs are enabled, because it wants
 583          * to self-test [hard/soft]-irqs on/off lock inversion bugs
 584          * too:
 585          */
 586         locking_selftest();
 587
 588 #ifdef CONFIG_BLK_DEV_INITRD
 589         if (initrd_start && !initrd_below_start_ok &&
 590             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 591                 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
 592                     page_to_pfn(virt_to_page((void *)initrd_start)),
 593                     min_low_pfn);
 594                 initrd_start = 0;
 595         }
 596 #endif
 597         page_cgroup_init();
 598         debug_objects_mem_init();
 599         kmemleak_init();
 600         setup_per_cpu_pageset();
 601         numa_policy_init();
 602         if (late_time_init)
 603                 late_time_init();
 604         sched_clock_init();
 605         calibrate_delay();
 606         pidmap_init();
 607         anon_vma_init();
 608 #ifdef CONFIG_X86
 609         if (efi_enabled(EFI_RUNTIME_SERVICES))
 610                 efi_enter_virtual_mode();
 611 #endif
 612         thread_info_cache_init();
 613         cred_init();
 614         fork_init(totalram_pages);
 615         proc_caches_init();
 616         buffer_init();
 617         key_init();
 618         security_init();
 619         dbg_late_init();
 620         vfs_caches_init(totalram_pages);
 621         signals_init();
 622         /* rootfs populating might need page-writeback */
 623         page_writeback_init();
 624 #ifdef CONFIG_PROC_FS
 625         proc_root_init();
 626 #endif
 627         cgroup_init();
 628         cpuset_init();
 629         taskstats_init_early();
 630         delayacct_init();
 631
 632         check_bugs();
 633
 634         acpi_early_init(); /* before LAPIC and SMP init */
 635         sfi_init_late();
 636
 637         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 638                 efi_late_init();
 639                 efi_free_boot_services();
 640         }
 641
 642         ftrace_init();
 643
 644         /* Do the rest non-__init'ed, we're now alive */
 645         rest_init();
 646 }
 647
 648 /* Call all constructor functions linked into the kernel. */
 649 static void __init do_ctors(void)
 650 {
 651 #ifdef CONFIG_CONSTRUCTORS
 652         ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
 653
 654         for (; fn < (ctor_fn_t *) __ctors_end; fn++)
 655                 (*fn)();
 656 #endif
 657 }
 658
 659 bool initcall_debug;
 660 core_param(initcall_debug, initcall_debug, bool, 0644);
 661
 662 static int __init_or_module do_one_initcall_debug(initcall_t fn)
 663 {
 664         ktime_t calltime, delta, rettime;
 665         unsigned long long duration;
 666         int ret;
 667
 668         pr_debug("calling  %pF @ %i\n", fn, task_pid_nr(current));
 669         calltime = ktime_get();
 670         ret = fn();
 671         rettime = ktime_get();
 672         delta = ktime_sub(rettime, calltime);
 673         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 674         pr_debug("initcall %pF returned %d after %lld usecs\n",
 675                  fn, ret, duration);
 676
 677         return ret;
 678 }
 679
 680 int __init_or_module do_one_initcall(initcall_t fn)
 681 {
 682         int count = preempt_count();
 683         int ret;
 684         char msgbuf[64];
 685
 686         if (initcall_debug)
 687                 ret = do_one_initcall_debug(fn);
 688         else
 689                 ret = fn();
 690
 691         msgbuf[0] = 0;
 692
 693         if (preempt_count() != count) {
 694                 sprintf(msgbuf, "preemption imbalance ");
 695                 preempt_count() = count;
 696         }
 697         if (irqs_disabled()) {
 698                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 699                 local_irq_enable();
 700         }
 701         WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
 702
 703         return ret;
 704 }
 705
 706
 707 extern initcall_t __initcall_start[];
 708 extern initcall_t __initcall0_start[];
 709 extern initcall_t __initcall1_start[];
 710 extern initcall_t __initcall2_start[];
 711 extern initcall_t __initcall3_start[];
 712 extern initcall_t __initcall4_start[];
 713 extern initcall_t __initcall5_start[];
 714 extern initcall_t __initcall6_start[];
 715 extern initcall_t __initcall7_start[];
 716 extern initcall_t __initcall_end[];
 717
 718 static initcall_t *initcall_levels[] __initdata = {
 719         __initcall0_start,
 720         __initcall1_start,
 721         __initcall2_start,
 722         __initcall3_start,
 723         __initcall4_start,
 724         __initcall5_start,
 725         __initcall6_start,
 726         __initcall7_start,
 727         __initcall_end,
 728 };
 729
 730 /* Keep these in sync with initcalls in include/linux/init.h */
 731 static char *initcall_level_names[] __initdata = {
 732         "early",
 733         "core",
 734         "postcore",
 735         "arch",
 736         "subsys",
 737         "fs",
 738         "device",
 739         "late",
 740 };
 741
 742 static void __init do_initcall_level(int level)
 743 {
 744         extern const struct kernel_param __start___param[], __stop___param[];
 745         initcall_t *fn;
 746
 747         strcpy(static_command_line, saved_command_line);
 748         parse_args(initcall_level_names[level],
 749                    static_command_line, __start___param,
 750                    __stop___param - __start___param,
 751                    level, level,
 752                    &repair_env_string);
 753
 754         for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
 755                 do_one_initcall(*fn);
 756 }
 757
 758 static void __init do_initcalls(void)
 759 {
 760         int level;
 761
 762         for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
 763                 do_initcall_level(level);
 764 }
 765
 766 /*
 767  * Ok, the machine is now initialized. None of the devices
 768  * have been touched yet, but the CPU subsystem is up and
 769  * running, and memory and process management works.
 770  *
 771  * Now we can finally start doing some real work..
 772  */
 773 static void __init do_basic_setup(void)
 774 {
 775         cpuset_init_smp();
 776         usermodehelper_init();
 777         shmem_init();
 778         driver_init();
 779         init_irq_proc();
 780         do_ctors();
 781         usermodehelper_enable();
 782         do_initcalls();
 783 }
 784
 785 static void __init do_pre_smp_initcalls(void)
 786 {
 787         initcall_t *fn;
 788
 789         for (fn = __initcall_start; fn < __initcall0_start; fn++)
 790                 do_one_initcall(*fn);
 791 }
 792
 793 /*
 794  * This function requests modules which should be loaded by default and is
 795  * called twice right after initrd is mounted and right before init is
 796  * exec'd.  If such modules are on either initrd or rootfs, they will be
 797  * loaded before control is passed to userland.
 798  */
 799 void __init load_default_modules(void)
 800 {
 801         load_default_elevator_module();
 802 }
 803
 804 static int run_init_process(const char *init_filename)
 805 {
 806         argv_init[0] = init_filename;
 807         return do_execve(init_filename,
 808                 (const char __user *const __user *)argv_init,
 809                 (const char __user *const __user *)envp_init);
 810 }
 811
 812 static noinline void __init kernel_init_freeable(void);
 813
 814 static int __ref kernel_init(void *unused)
 815 {
 816         kernel_init_freeable();
 817         /* need to finish all async __init code before freeing the memory */
 818         async_synchronize_full();
 819         free_initmem();
 820         mark_rodata_ro();
 821         system_state = SYSTEM_RUNNING;
 822         numa_default_policy();
 823
 824         flush_delayed_fput();
 825
 826         if (ramdisk_execute_command) {
 827                 if (!run_init_process(ramdisk_execute_command))
 828                         return 0;
 829                 pr_err("Failed to execute %s\n", ramdisk_execute_command);
 830         }
 831
 832         /*
 833          * We try each of these until one succeeds.
 834          *
 835          * The Bourne shell can be used instead of init if we are
 836          * trying to recover a really broken machine.
 837          */
 838         if (execute_command) {
 839                 if (!run_init_process(execute_command))
 840                         return 0;
 841                 pr_err("Failed to execute %s.  Attempting defaults...\n",
 842                         execute_command);
 843         }
 844         if (!run_init_process("/sbin/init") ||
 845             !run_init_process("/etc/init") ||
 846             !run_init_process("/bin/init") ||
 847             !run_init_process("/bin/sh"))
 848                 return 0;
 849
 850         panic("No init found.  Try passing init= option to kernel. "
 851               "See Linux Documentation/init.txt for guidance.");
 852 }
 853
 854 static noinline void __init kernel_init_freeable(void)
 855 {
 856         /*
 857          * Wait until kthreadd is all set-up.
 858          */
 859         wait_for_completion(&kthreadd_done);
 860
 861         /* Now the scheduler is fully set up and can do blocking allocations */
 862         gfp_allowed_mask = __GFP_BITS_MASK;
 863
 864         /*
 865          * init can allocate pages on any node
 866          */
 867         set_mems_allowed(node_states[N_MEMORY]);
 868         /*
 869          * init can run on any cpu.
 870          */
 871         set_cpus_allowed_ptr(current, cpu_all_mask);
 872
 873         cad_pid = task_pid(current);
 874
 875         smp_prepare_cpus(setup_max_cpus);
 876
 877         do_pre_smp_initcalls();
 878         lockup_detector_init();
 879
 880         smp_init();
 881         sched_init_smp();
 882
 883         do_basic_setup();
 884
 885         /* Open the /dev/console on the rootfs, this should never fail */
 886         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 887                 pr_err("Warning: unable to open an initial console.\n");
 888
 889         (void) sys_dup(0);
 890         (void) sys_dup(0);
 891         /*
 892          * check if there is an early userspace init.  If yes, let it do all
 893          * the work
 894          */
 895
 896         if (!ramdisk_execute_command)
 897                 ramdisk_execute_command = "/init";
 898
 899         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 900                 ramdisk_execute_command = NULL;
 901                 prepare_namespace();
 902         }
 903
 904         /*
 905          * Ok, we have completed the initial bootup, and
 906          * we're essentially up and running. Get rid of the
 907          * initmem segments and start the user-mode stuff..
 908          */
 909
 910         /* rootfs is available now, try loading default modules */
 911         load_default_modules();
 912 }