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
  79 #include <asm/io.h>
  80 #include <asm/bugs.h>
  81 #include <asm/setup.h>
  82 #include <asm/sections.h>
  83 #include <asm/cacheflush.h>
  84
  85 #ifdef CONFIG_X86_LOCAL_APIC
  86 #include <asm/smp.h>
  87 #endif
  88
  89 static int kernel_init(void *);
  90
  91 extern void init_IRQ(void);
  92 extern void fork_init(unsigned long);
  93 extern void mca_init(void);
  94 extern void sbus_init(void);
  95 extern void radix_tree_init(void);
  96 #ifndef CONFIG_DEBUG_RODATA
  97 static inline void mark_rodata_ro(void) { }
  98 #endif
  99
 100 #ifdef CONFIG_TC
 101 extern void tc_init(void);
 102 #endif
 103
 104 /*
 105  * Debug helper: via this flag we know that we are in 'early bootup code'
 106  * where only the boot processor is running with IRQ disabled.  This means
 107  * two things - IRQ must not be enabled before the flag is cleared and some
 108  * operations which are not allowed with IRQ disabled are allowed while the
 109  * flag is set.
 110  */
 111 bool early_boot_irqs_disabled __read_mostly;
 112
 113 enum system_states system_state __read_mostly;
 114 EXPORT_SYMBOL(system_state);
 115
 116 /*
 117  * Boot command-line arguments
 118  */
 119 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 120 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 121
 122 extern void time_init(void);
 123 /* Default late time init is NULL. archs can override this later. */
 124 void (*__initdata late_time_init)(void);
 125 extern void softirq_init(void);
 126
 127 /* Untouched command line saved by arch-specific code. */
 128 char __initdata boot_command_line[COMMAND_LINE_SIZE];
 129 /* Untouched saved command line (eg. for /proc) */
 130 char *saved_command_line;
 131 /* Command line for parameter parsing */
 132 static char *static_command_line;
 133
 134 static char *execute_command;
 135 static char *ramdisk_execute_command;
 136
 137 /*
 138  * If set, this is an indication to the drivers that reset the underlying
 139  * device before going ahead with the initialization otherwise driver might
 140  * rely on the BIOS and skip the reset operation.
 141  *
 142  * This is useful if kernel is booting in an unreliable environment.
 143  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 144  * skipped and devices will be in unknown state.
 145  */
 146 unsigned int reset_devices;
 147 EXPORT_SYMBOL(reset_devices);
 148
 149 static int __init set_reset_devices(char *str)
 150 {
 151         reset_devices = 1;
 152         return 1;
 153 }
 154
 155 __setup("reset_devices", set_reset_devices);
 156
 157 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 158 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 159 static const char *panic_later, *panic_param;
 160
 161 extern const struct obs_kernel_param __setup_start[], __setup_end[];
 162
 163 static int __init obsolete_checksetup(char *line)
 164 {
 165         const struct obs_kernel_param *p;
 166         int had_early_param = 0;
 167
 168         p = __setup_start;
 169         do {
 170                 int n = strlen(p->str);
 171                 if (parameqn(line, p->str, n)) {
 172                         if (p->early) {
 173                                 /* Already done in parse_early_param?
 174                                  * (Needs exact match on param part).
 175                                  * Keep iterating, as we can have early
 176                                  * params and __setups of same names 8( */
 177                                 if (line[n] == '\0' || line[n] == '=')
 178                                         had_early_param = 1;
 179                         } else if (!p->setup_func) {
 180                                 pr_warn("Parameter %s is obsolete, ignored\n",
 181                                         p->str);
 182                                 return 1;
 183                         } else if (p->setup_func(line + n))
 184                                 return 1;
 185                 }
 186                 p++;
 187         } while (p < __setup_end);
 188
 189         return had_early_param;
 190 }
 191
 192 /*
 193  * This should be approx 2 Bo*oMips to start (note initial shift), and will
 194  * still work even if initially too large, it will just take slightly longer
 195  */
 196 unsigned long loops_per_jiffy = (1<<12);
 197
 198 EXPORT_SYMBOL(loops_per_jiffy);
 199
 200 static int __init debug_kernel(char *str)
 201 {
 202         console_loglevel = 10;
 203         return 0;
 204 }
 205
 206 static int __init quiet_kernel(char *str)
 207 {
 208         console_loglevel = 4;
 209         return 0;
 210 }
 211
 212 early_param("debug", debug_kernel);
 213 early_param("quiet", quiet_kernel);
 214
 215 static int __init loglevel(char *str)
 216 {
 217         int newlevel;
 218
 219         /*
 220          * Only update loglevel value when a correct setting was passed,
 221          * to prevent blind crashes (when loglevel being set to 0) that
 222          * are quite hard to debug
 223          */
 224         if (get_option(&str, &newlevel)) {
 225                 console_loglevel = newlevel;
 226                 return 0;
 227         }
 228
 229         return -EINVAL;
 230 }
 231
 232 early_param("loglevel", loglevel);
 233
 234 /* Change NUL term back to "=", to make "param" the whole string. */
 235 static int __init repair_env_string(char *param, char *val, const char *unused)
 236 {
 237         if (val) {
 238                 /* param=val or param="val"? */
 239                 if (val == param+strlen(param)+1)
 240                         val[-1] = '=';
 241                 else if (val == param+strlen(param)+2) {
 242                         val[-2] = '=';
 243                         memmove(val-1, val, strlen(val)+1);
 244                         val--;
 245                 } else
 246                         BUG();
 247         }
 248         return 0;
 249 }
 250
 251 /*
 252  * Unknown boot options get handed to init, unless they look like
 253  * unused parameters (modprobe will find them in /proc/cmdline).
 254  */
 255 static int __init unknown_bootoption(char *param, char *val, const char *unused)
 256 {
 257         repair_env_string(param, val, unused);
 258
 259         /* Handle obsolete-style parameters */
 260         if (obsolete_checksetup(param))
 261                 return 0;
 262
 263         /* Unused module parameter. */
 264         if (strchr(param, '.') && (!val || strchr(param, '.') < val))
 265                 return 0;
 266
 267         if (panic_later)
 268                 return 0;
 269
 270         if (val) {
 271                 /* Environment option */
 272                 unsigned int i;
 273                 for (i = 0; envp_init[i]; i++) {
 274                         if (i == MAX_INIT_ENVS) {
 275                                 panic_later = "Too many boot env vars at `%s'";
 276                                 panic_param = param;
 277                         }
 278                         if (!strncmp(param, envp_init[i], val - param))
 279                                 break;
 280                 }
 281                 envp_init[i] = param;
 282         } else {
 283                 /* Command line option */
 284                 unsigned int i;
 285                 for (i = 0; argv_init[i]; i++) {
 286                         if (i == MAX_INIT_ARGS) {
 287                                 panic_later = "Too many boot init vars at `%s'";
 288                                 panic_param = param;
 289                         }
 290                 }
 291                 argv_init[i] = param;
 292         }
 293         return 0;
 294 }
 295
 296 static int __init init_setup(char *str)
 297 {
 298         unsigned int i;
 299
 300         execute_command = str;
 301         /*
 302          * In case LILO is going to boot us with default command line,
 303          * it prepends "auto" before the whole cmdline which makes
 304          * the shell think it should execute a script with such name.
 305          * So we ignore all arguments entered _before_ init=... [MJ]
 306          */
 307         for (i = 1; i < MAX_INIT_ARGS; i++)
 308                 argv_init[i] = NULL;
 309         return 1;
 310 }
 311 __setup("init=", init_setup);
 312
 313 static int __init rdinit_setup(char *str)
 314 {
 315         unsigned int i;
 316
 317         ramdisk_execute_command = str;
 318         /* See "auto" comment in init_setup */
 319         for (i = 1; i < MAX_INIT_ARGS; i++)
 320                 argv_init[i] = NULL;
 321         return 1;
 322 }
 323 __setup("rdinit=", rdinit_setup);
 324
 325 #ifndef CONFIG_SMP
 326 static const unsigned int setup_max_cpus = NR_CPUS;
 327 #ifdef CONFIG_X86_LOCAL_APIC
 328 static void __init smp_init(void)
 329 {
 330         APIC_init_uniprocessor();
 331 }
 332 #else
 333 #define smp_init()      do { } while (0)
 334 #endif
 335
 336 static inline void setup_nr_cpu_ids(void) { }
 337 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 338 #endif
 339
 340 /*
 341  * We need to store the untouched command line for future reference.
 342  * We also need to store the touched command line since the parameter
 343  * parsing is performed in place, and we should allow a component to
 344  * store reference of name/value for future reference.
 345  */
 346 static void __init setup_command_line(char *command_line)
 347 {
 348         saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 349         static_command_line = alloc_bootmem(strlen (command_line)+1);
 350         strcpy (saved_command_line, boot_command_line);
 351         strcpy (static_command_line, command_line);
 352 }
 353
 354 /*
 355  * We need to finalize in a non-__init function or else race conditions
 356  * between the root thread and the init thread may cause start_kernel to
 357  * be reaped by free_initmem before the root thread has proceeded to
 358  * cpu_idle.
 359  *
 360  * gcc-3.4 accidentally inlines this function, so use noinline.
 361  */
 362
 363 static __initdata DECLARE_COMPLETION(kthreadd_done);
 364
 365 static noinline void __init_refok rest_init(void)
 366 {
 367         int pid;
 368
 369         rcu_scheduler_starting();
 370         /*
 371          * We need to spawn init first so that it obtains pid 1, however
 372          * the init task will end up wanting to create kthreads, which, if
 373          * we schedule it before we create kthreadd, will OOPS.
 374          */
 375         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 376         numa_default_policy();
 377         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 378         rcu_read_lock();
 379         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 380         rcu_read_unlock();
 381         complete(&kthreadd_done);
 382
 383         /*
 384          * The boot idle thread must execute schedule()
 385          * at least once to get things moving:
 386          */
 387         init_idle_bootup_task(current);
 388         schedule_preempt_disabled();
 389         /* Call into cpu_idle with preempt disabled */
 390         cpu_startup_entry(CPUHP_ONLINE);
 391 }
 392
 393 /* Check for early params. */
 394 static int __init do_early_param(char *param, char *val, const char *unused)
 395 {
 396         const struct obs_kernel_param *p;
 397
 398         for (p = __setup_start; p < __setup_end; p++) {
 399                 if ((p->early && parameq(param, p->str)) ||
 400                     (strcmp(param, "console") == 0 &&
 401                      strcmp(p->str, "earlycon") == 0)
 402                 ) {
 403                         if (p->setup_func(val) != 0)
 404                                 pr_warn("Malformed early option '%s'\n", param);
 405                 }
 406         }
 407         /* We accept everything at this stage. */
 408         return 0;
 409 }
 410
 411 void __init parse_early_options(char *cmdline)
 412 {
 413         parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
 414 }
 415
 416 /* Arch code calls this early on, or if not, just before other parsing. */
 417 void __init parse_early_param(void)
 418 {
 419         static __initdata int done = 0;
 420         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 421
 422         if (done)
 423                 return;
 424
 425         /* All fall through to do_early_param. */
 426         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 427         parse_early_options(tmp_cmdline);
 428         done = 1;
 429 }
 430
 431 /*
 432  *      Activate the first processor.
 433  */
 434
 435 static void __init boot_cpu_init(void)
 436 {
 437         int cpu = smp_processor_id();
 438         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 439         set_cpu_online(cpu, true);
 440         set_cpu_active(cpu, true);
 441         set_cpu_present(cpu, true);
 442         set_cpu_possible(cpu, true);
 443 }
 444
 445 void __init __weak smp_setup_processor_id(void)
 446 {
 447 }
 448
 449 # if THREAD_SIZE >= PAGE_SIZE
 450 void __init __weak thread_info_cache_init(void)
 451 {
 452 }
 453 #endif
 454
 455 /*
 456  * Set up kernel memory allocators
 457  */
 458 static void __init mm_init(void)
 459 {
 460         /*
 461          * page_cgroup requires contiguous pages,
 462          * bigger than MAX_ORDER unless SPARSEMEM.
 463          */
 464         page_cgroup_init_flatmem();
 465         mem_init();
 466         kmem_cache_init();
 467         percpu_init_late();
 468         pgtable_cache_init();
 469         vmalloc_init();
 470 }
 471
 472 asmlinkage void __init start_kernel(void)
 473 {
 474         char * command_line;
 475         extern const struct kernel_param __start___param[], __stop___param[];
 476
 477         /*
 478          * Need to run as early as possible, to initialize the
 479          * lockdep hash:
 480          */
 481         lockdep_init();
 482         smp_setup_processor_id();
 483         debug_objects_early_init();
 484
 485         /*
 486          * Set up the the initial canary ASAP:
 487          */
 488         boot_init_stack_canary();
 489
 490         cgroup_init_early();
 491
 492         local_irq_disable();
 493         early_boot_irqs_disabled = true;
 494
 495 /*
 496  * Interrupts are still disabled. Do necessary setups, then
 497  * enable them
 498  */
 499         boot_cpu_init();
 500         page_address_init();
 501         pr_notice("%s", linux_banner);
 502         setup_arch(&command_line);
 503         mm_init_owner(&init_mm, &init_task);
 504         mm_init_cpumask(&init_mm);
 505         setup_command_line(command_line);
 506         setup_nr_cpu_ids();
 507         setup_per_cpu_areas();
 508         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 509
 510         build_all_zonelists(NULL, NULL);
 511         page_alloc_init();
 512
 513         pr_notice("Kernel command line: %s\n", boot_command_line);
 514         parse_early_param();
 515         parse_args("Booting kernel", static_command_line, __start___param,
 516                    __stop___param - __start___param,
 517                    -1, -1, &unknown_bootoption);
 518
 519         jump_label_init();
 520
 521         /*
 522          * These use large bootmem allocations and must precede
 523          * kmem_cache_init()
 524          */
 525         setup_log_buf(0);
 526         pidhash_init();
 527         vfs_caches_init_early();
 528         sort_main_extable();
 529         trap_init();
 530         mm_init();
 531
 532         /*
 533          * Set up the scheduler prior starting any interrupts (such as the
 534          * timer interrupt). Full topology setup happens at smp_init()
 535          * time - but meanwhile we still have a functioning scheduler.
 536          */
 537         sched_init();
 538         /*
 539          * Disable preemption - early bootup scheduling is extremely
 540          * fragile until we cpu_idle() for the first time.
 541          */
 542         preempt_disable();
 543         if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
 544                 local_irq_disable();
 545         idr_init_cache();
 546         rcu_init();
 547         tick_nohz_init();
 548         radix_tree_init();
 549         /* init some links before init_ISA_irqs() */
 550         early_irq_init();
 551         init_IRQ();
 552         tick_init();
 553         init_timers();
 554         hrtimers_init();
 555         softirq_init();
 556         timekeeping_init();
 557         time_init();
 558         sched_clock_postinit();
 559         perf_event_init();
 560         profile_init();
 561         call_function_init();
 562         WARN(!irqs_disabled(), "Interrupts were enabled early\n");
 563         early_boot_irqs_disabled = false;
 564         local_irq_enable();
 565
 566         kmem_cache_init_late();
 567
 568         /*
 569          * HACK ALERT! This is early. We're enabling the console before
 570          * we've done PCI setups etc, and console_init() must be aware of
 571          * this. But we do want output early, in case something goes wrong.
 572          */
 573         console_init();
 574         if (panic_later)
 575                 panic(panic_later, panic_param);
 576
 577         lockdep_info();
 578
 579         /*
 580          * Need to run this when irqs are enabled, because it wants
 581          * to self-test [hard/soft]-irqs on/off lock inversion bugs
 582          * too:
 583          */
 584         locking_selftest();
 585
 586 #ifdef CONFIG_BLK_DEV_INITRD
 587         if (initrd_start && !initrd_below_start_ok &&
 588             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 589                 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
 590                     page_to_pfn(virt_to_page((void *)initrd_start)),
 591                     min_low_pfn);
 592                 initrd_start = 0;
 593         }
 594 #endif
 595         page_cgroup_init();
 596         debug_objects_mem_init();
 597         kmemleak_init();
 598         setup_per_cpu_pageset();
 599         numa_policy_init();
 600         if (late_time_init)
 601                 late_time_init();
 602         sched_clock_init();
 603         calibrate_delay();
 604         pidmap_init();
 605         anon_vma_init();
 606 #ifdef CONFIG_X86
 607         if (efi_enabled(EFI_RUNTIME_SERVICES))
 608                 efi_enter_virtual_mode();
 609 #endif
 610         thread_info_cache_init();
 611         cred_init();
 612         fork_init(totalram_pages);
 613         proc_caches_init();
 614         buffer_init();
 615         key_init();
 616         security_init();
 617         dbg_late_init();
 618         vfs_caches_init(totalram_pages);
 619         signals_init();
 620         /* rootfs populating might need page-writeback */
 621         page_writeback_init();
 622 #ifdef CONFIG_PROC_FS
 623         proc_root_init();
 624 #endif
 625         cgroup_init();
 626         cpuset_init();
 627         taskstats_init_early();
 628         delayacct_init();
 629
 630         check_bugs();
 631
 632         acpi_early_init(); /* before LAPIC and SMP init */
 633         sfi_init_late();
 634
 635         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 636                 efi_late_init();
 637                 efi_free_boot_services();
 638         }
 639
 640         ftrace_init();
 641
 642         /* Do the rest non-__init'ed, we're now alive */
 643         rest_init();
 644 }
 645
 646 /* Call all constructor functions linked into the kernel. */
 647 static void __init do_ctors(void)
 648 {
 649 #ifdef CONFIG_CONSTRUCTORS
 650         ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
 651
 652         for (; fn < (ctor_fn_t *) __ctors_end; fn++)
 653                 (*fn)();
 654 #endif
 655 }
 656
 657 bool initcall_debug;
 658 core_param(initcall_debug, initcall_debug, bool, 0644);
 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         char msgbuf[64];
 683
 684         if (initcall_debug)
 685                 ret = do_one_initcall_debug(fn);
 686         else
 687                 ret = fn();
 688
 689         msgbuf[0] = 0;
 690
 691         if (preempt_count() != count) {
 692                 sprintf(msgbuf, "preemption imbalance ");
 693                 preempt_count() = count;
 694         }
 695         if (irqs_disabled()) {
 696                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 697                 local_irq_enable();
 698         }
 699         WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
 700
 701         return ret;
 702 }
 703
 704
 705 extern initcall_t __initcall_start[];
 706 extern initcall_t __initcall0_start[];
 707 extern initcall_t __initcall1_start[];
 708 extern initcall_t __initcall2_start[];
 709 extern initcall_t __initcall3_start[];
 710 extern initcall_t __initcall4_start[];
 711 extern initcall_t __initcall5_start[];
 712 extern initcall_t __initcall6_start[];
 713 extern initcall_t __initcall7_start[];
 714 extern initcall_t __initcall_end[];
 715
 716 static initcall_t *initcall_levels[] __initdata = {
 717         __initcall0_start,
 718         __initcall1_start,
 719         __initcall2_start,
 720         __initcall3_start,
 721         __initcall4_start,
 722         __initcall5_start,
 723         __initcall6_start,
 724         __initcall7_start,
 725         __initcall_end,
 726 };
 727
 728 /* Keep these in sync with initcalls in include/linux/init.h */
 729 static char *initcall_level_names[] __initdata = {
 730         "early",
 731         "core",
 732         "postcore",
 733         "arch",
 734         "subsys",
 735         "fs",
 736         "device",
 737         "late",
 738 };
 739
 740 static void __init do_initcall_level(int level)
 741 {
 742         extern const struct kernel_param __start___param[], __stop___param[];
 743         initcall_t *fn;
 744
 745         strcpy(static_command_line, saved_command_line);
 746         parse_args(initcall_level_names[level],
 747                    static_command_line, __start___param,
 748                    __stop___param - __start___param,
 749                    level, level,
 750                    &repair_env_string);
 751
 752         for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
 753                 do_one_initcall(*fn);
 754 }
 755
 756 static void __init do_initcalls(void)
 757 {
 758         int level;
 759
 760         for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
 761                 do_initcall_level(level);
 762 }
 763
 764 /*
 765  * Ok, the machine is now initialized. None of the devices
 766  * have been touched yet, but the CPU subsystem is up and
 767  * running, and memory and process management works.
 768  *
 769  * Now we can finally start doing some real work..
 770  */
 771 static void __init do_basic_setup(void)
 772 {
 773         cpuset_init_smp();
 774         usermodehelper_init();
 775         shmem_init();
 776         driver_init();
 777         init_irq_proc();
 778         do_ctors();
 779         usermodehelper_enable();
 780         do_initcalls();
 781 }
 782
 783 static void __init do_pre_smp_initcalls(void)
 784 {
 785         initcall_t *fn;
 786
 787         for (fn = __initcall_start; fn < __initcall0_start; fn++)
 788                 do_one_initcall(*fn);
 789 }
 790
 791 /*
 792  * This function requests modules which should be loaded by default and is
 793  * called twice right after initrd is mounted and right before init is
 794  * exec'd.  If such modules are on either initrd or rootfs, they will be
 795  * loaded before control is passed to userland.
 796  */
 797 void __init load_default_modules(void)
 798 {
 799         load_default_elevator_module();
 800 }
 801
 802 static int run_init_process(const char *init_filename)
 803 {
 804         argv_init[0] = init_filename;
 805         return do_execve(init_filename,
 806                 (const char __user *const __user *)argv_init,
 807                 (const char __user *const __user *)envp_init);
 808 }
 809
 810 static noinline void __init kernel_init_freeable(void);
 811
 812 static int __ref kernel_init(void *unused)
 813 {
 814         kernel_init_freeable();
 815         /* need to finish all async __init code before freeing the memory */
 816         async_synchronize_full();
 817         free_initmem();
 818         mark_rodata_ro();
 819         system_state = SYSTEM_RUNNING;
 820         numa_default_policy();
 821
 822         flush_delayed_fput();
 823
 824         if (ramdisk_execute_command) {
 825                 if (!run_init_process(ramdisk_execute_command))
 826                         return 0;
 827                 pr_err("Failed to execute %s\n", ramdisk_execute_command);
 828         }
 829
 830         /*
 831          * We try each of these until one succeeds.
 832          *
 833          * The Bourne shell can be used instead of init if we are
 834          * trying to recover a really broken machine.
 835          */
 836         if (execute_command) {
 837                 if (!run_init_process(execute_command))
 838                         return 0;
 839                 pr_err("Failed to execute %s.  Attempting defaults...\n",
 840                         execute_command);
 841         }
 842         if (!run_init_process("/sbin/init") ||
 843             !run_init_process("/etc/init") ||
 844             !run_init_process("/bin/init") ||
 845             !run_init_process("/bin/sh"))
 846                 return 0;
 847
 848         panic("No init found.  Try passing init= option to kernel. "
 849               "See Linux Documentation/init.txt for guidance.");
 850 }
 851
 852 static noinline void __init kernel_init_freeable(void)
 853 {
 854         /*
 855          * Wait until kthreadd is all set-up.
 856          */
 857         wait_for_completion(&kthreadd_done);
 858
 859         /* Now the scheduler is fully set up and can do blocking allocations */
 860         gfp_allowed_mask = __GFP_BITS_MASK;
 861
 862         /*
 863          * init can allocate pages on any node
 864          */
 865         set_mems_allowed(node_states[N_MEMORY]);
 866         /*
 867          * init can run on any cpu.
 868          */
 869         set_cpus_allowed_ptr(current, cpu_all_mask);
 870
 871         cad_pid = task_pid(current);
 872
 873         smp_prepare_cpus(setup_max_cpus);
 874
 875         do_pre_smp_initcalls();
 876         lockup_detector_init();
 877
 878         smp_init();
 879         sched_init_smp();
 880
 881         do_basic_setup();
 882
 883         /* Open the /dev/console on the rootfs, this should never fail */
 884         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 885                 pr_err("Warning: unable to open an initial console.\n");
 886
 887         (void) sys_dup(0);
 888         (void) sys_dup(0);
 889         /*
 890          * check if there is an early userspace init.  If yes, let it do all
 891          * the work
 892          */
 893
 894         if (!ramdisk_execute_command)
 895                 ramdisk_execute_command = "/init";
 896
 897         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 898                 ramdisk_execute_command = NULL;
 899                 prepare_namespace();
 900         }
 901
 902         /*
 903          * Ok, we have completed the initial bootup, and
 904          * we're essentially up and running. Get rid of the
 905          * initmem segments and start the user-mode stuff..
 906          */
 907
 908         /* rootfs is available now, try loading default modules */
 909         load_default_modules();
 910 }