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 #include <linux/random.h>
  80
  81 #include <asm/io.h>
  82 #include <asm/bugs.h>
  83 #include <asm/setup.h>
  84 #include <asm/sections.h>
  85 #include <asm/cacheflush.h>
  86
  87 #ifdef CONFIG_X86_LOCAL_APIC
  88 #include <asm/smp.h>
  89 #endif
  90
  91 static int kernel_init(void *);
  92
  93 extern void init_IRQ(void);
  94 extern void fork_init(unsigned long);
  95 extern void mca_init(void);
  96 extern void sbus_init(void);
  97 extern void radix_tree_init(void);
  98 #ifndef CONFIG_DEBUG_RODATA
  99 static inline void mark_rodata_ro(void) { }
 100 #endif
 101
 102 #ifdef CONFIG_TC
 103 extern void tc_init(void);
 104 #endif
 105
 106 /*
 107  * Debug helper: via this flag we know that we are in 'early bootup code'
 108  * where only the boot processor is running with IRQ disabled.  This means
 109  * two things - IRQ must not be enabled before the flag is cleared and some
 110  * operations which are not allowed with IRQ disabled are allowed while the
 111  * flag is set.
 112  */
 113 bool early_boot_irqs_disabled __read_mostly;
 114
 115 enum system_states system_state __read_mostly;
 116 EXPORT_SYMBOL(system_state);
 117
 118 /*
 119  * Boot command-line arguments
 120  */
 121 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 122 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 123
 124 extern void time_init(void);
 125 /* Default late time init is NULL. archs can override this later. */
 126 void (*__initdata late_time_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 /* Command line for per-initcall parameter parsing */
 135 static char *initcall_command_line;
 136
 137 static char *execute_command;
 138 static char *ramdisk_execute_command;
 139
 140 /*
 141  * Used to generate warnings if static_key manipulation functions are used
 142  * before jump_label_init is called.
 143  */
 144 bool static_key_initialized __read_mostly = false;
 145 EXPORT_SYMBOL_GPL(static_key_initialized);
 146
 147 /*
 148  * If set, this is an indication to the drivers that reset the underlying
 149  * device before going ahead with the initialization otherwise driver might
 150  * rely on the BIOS and skip the reset operation.
 151  *
 152  * This is useful if kernel is booting in an unreliable environment.
 153  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 154  * skipped and devices will be in unknown state.
 155  */
 156 unsigned int reset_devices;
 157 EXPORT_SYMBOL(reset_devices);
 158
 159 static int __init set_reset_devices(char *str)
 160 {
 161         reset_devices = 1;
 162         return 1;
 163 }
 164
 165 __setup("reset_devices", set_reset_devices);
 166
 167 static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 168 const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 169 static const char *panic_later, *panic_param;
 170
 171 extern const struct obs_kernel_param __setup_start[], __setup_end[];
 172
 173 static int __init obsolete_checksetup(char *line)
 174 {
 175         const struct obs_kernel_param *p;
 176         int had_early_param = 0;
 177
 178         p = __setup_start;
 179         do {
 180                 int n = strlen(p->str);
 181                 if (parameqn(line, p->str, n)) {
 182                         if (p->early) {
 183                                 /* Already done in parse_early_param?
 184                                  * (Needs exact match on param part).
 185                                  * Keep iterating, as we can have early
 186                                  * params and __setups of same names 8( */
 187                                 if (line[n] == '\0' || line[n] == '=')
 188                                         had_early_param = 1;
 189                         } else if (!p->setup_func) {
 190                                 pr_warn("Parameter %s is obsolete, ignored\n",
 191                                         p->str);
 192                                 return 1;
 193                         } else if (p->setup_func(line + n))
 194                                 return 1;
 195                 }
 196                 p++;
 197         } while (p < __setup_end);
 198
 199         return had_early_param;
 200 }
 201
 202 /*
 203  * This should be approx 2 Bo*oMips to start (note initial shift), and will
 204  * still work even if initially too large, it will just take slightly longer
 205  */
 206 unsigned long loops_per_jiffy = (1<<12);
 207
 208 EXPORT_SYMBOL(loops_per_jiffy);
 209
 210 static int __init debug_kernel(char *str)
 211 {
 212         console_loglevel = 10;
 213         return 0;
 214 }
 215
 216 static int __init quiet_kernel(char *str)
 217 {
 218         console_loglevel = 4;
 219         return 0;
 220 }
 221
 222 early_param("debug", debug_kernel);
 223 early_param("quiet", quiet_kernel);
 224
 225 static int __init loglevel(char *str)
 226 {
 227         int newlevel;
 228
 229         /*
 230          * Only update loglevel value when a correct setting was passed,
 231          * to prevent blind crashes (when loglevel being set to 0) that
 232          * are quite hard to debug
 233          */
 234         if (get_option(&str, &newlevel)) {
 235                 console_loglevel = newlevel;
 236                 return 0;
 237         }
 238
 239         return -EINVAL;
 240 }
 241
 242 early_param("loglevel", loglevel);
 243
 244 /* Change NUL term back to "=", to make "param" the whole string. */
 245 static int __init repair_env_string(char *param, char *val, const char *unused)
 246 {
 247         if (val) {
 248                 /* param=val or param="val"? */
 249                 if (val == param+strlen(param)+1)
 250                         val[-1] = '=';
 251                 else if (val == param+strlen(param)+2) {
 252                         val[-2] = '=';
 253                         memmove(val-1, val, strlen(val)+1);
 254                         val--;
 255                 } else
 256                         BUG();
 257         }
 258         return 0;
 259 }
 260
 261 /*
 262  * Unknown boot options get handed to init, unless they look like
 263  * unused parameters (modprobe will find them in /proc/cmdline).
 264  */
 265 static int __init unknown_bootoption(char *param, char *val, const char *unused)
 266 {
 267         repair_env_string(param, val, unused);
 268
 269         /* Handle obsolete-style parameters */
 270         if (obsolete_checksetup(param))
 271                 return 0;
 272
 273         /* Unused module parameter. */
 274         if (strchr(param, '.') && (!val || strchr(param, '.') < val))
 275                 return 0;
 276
 277         if (panic_later)
 278                 return 0;
 279
 280         if (val) {
 281                 /* Environment option */
 282                 unsigned int i;
 283                 for (i = 0; envp_init[i]; i++) {
 284                         if (i == MAX_INIT_ENVS) {
 285                                 panic_later = "Too many boot env vars at `%s'";
 286                                 panic_param = param;
 287                         }
 288                         if (!strncmp(param, envp_init[i], val - param))
 289                                 break;
 290                 }
 291                 envp_init[i] = param;
 292         } else {
 293                 /* Command line option */
 294                 unsigned int i;
 295                 for (i = 0; argv_init[i]; i++) {
 296                         if (i == MAX_INIT_ARGS) {
 297                                 panic_later = "Too many boot init vars at `%s'";
 298                                 panic_param = param;
 299                         }
 300                 }
 301                 argv_init[i] = param;
 302         }
 303         return 0;
 304 }
 305
 306 static int __init init_setup(char *str)
 307 {
 308         unsigned int i;
 309
 310         execute_command = str;
 311         /*
 312          * In case LILO is going to boot us with default command line,
 313          * it prepends "auto" before the whole cmdline which makes
 314          * the shell think it should execute a script with such name.
 315          * So we ignore all arguments entered _before_ init=... [MJ]
 316          */
 317         for (i = 1; i < MAX_INIT_ARGS; i++)
 318                 argv_init[i] = NULL;
 319         return 1;
 320 }
 321 __setup("init=", init_setup);
 322
 323 static int __init rdinit_setup(char *str)
 324 {
 325         unsigned int i;
 326
 327         ramdisk_execute_command = str;
 328         /* See "auto" comment in init_setup */
 329         for (i = 1; i < MAX_INIT_ARGS; i++)
 330                 argv_init[i] = NULL;
 331         return 1;
 332 }
 333 __setup("rdinit=", rdinit_setup);
 334
 335 #ifndef CONFIG_SMP
 336 static const unsigned int setup_max_cpus = NR_CPUS;
 337 #ifdef CONFIG_X86_LOCAL_APIC
 338 static void __init smp_init(void)
 339 {
 340         APIC_init_uniprocessor();
 341 }
 342 #else
 343 #define smp_init()      do { } while (0)
 344 #endif
 345
 346 static inline void setup_nr_cpu_ids(void) { }
 347 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 348 #endif
 349
 350 /*
 351  * We need to store the untouched command line for future reference.
 352  * We also need to store the touched command line since the parameter
 353  * parsing is performed in place, and we should allow a component to
 354  * store reference of name/value for future reference.
 355  */
 356 static void __init setup_command_line(char *command_line)
 357 {
 358         saved_command_line =
 359                 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
 360         initcall_command_line =
 361                 memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
 362         static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
 363         strcpy (saved_command_line, boot_command_line);
 364         strcpy (static_command_line, command_line);
 365 }
 366
 367 /*
 368  * We need to finalize in a non-__init function or else race conditions
 369  * between the root thread and the init thread may cause start_kernel to
 370  * be reaped by free_initmem before the root thread has proceeded to
 371  * cpu_idle.
 372  *
 373  * gcc-3.4 accidentally inlines this function, so use noinline.
 374  */
 375
 376 static __initdata DECLARE_COMPLETION(kthreadd_done);
 377
 378 static noinline void __init_refok rest_init(void)
 379 {
 380         int pid;
 381
 382         rcu_scheduler_starting();
 383         /*
 384          * We need to spawn init first so that it obtains pid 1, however
 385          * the init task will end up wanting to create kthreads, which, if
 386          * we schedule it before we create kthreadd, will OOPS.
 387          */
 388         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 389         numa_default_policy();
 390         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 391         rcu_read_lock();
 392         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 393         rcu_read_unlock();
 394         complete(&kthreadd_done);
 395
 396         /*
 397          * The boot idle thread must execute schedule()
 398          * at least once to get things moving:
 399          */
 400         init_idle_bootup_task(current);
 401         schedule_preempt_disabled();
 402         /* Call into cpu_idle with preempt disabled */
 403         cpu_startup_entry(CPUHP_ONLINE);
 404 }
 405
 406 /* Check for early params. */
 407 static int __init do_early_param(char *param, char *val, const char *unused)
 408 {
 409         const struct obs_kernel_param *p;
 410
 411         for (p = __setup_start; p < __setup_end; p++) {
 412                 if ((p->early && parameq(param, p->str)) ||
 413                     (strcmp(param, "console") == 0 &&
 414                      strcmp(p->str, "earlycon") == 0)
 415                 ) {
 416                         if (p->setup_func(val) != 0)
 417                                 pr_warn("Malformed early option '%s'\n", param);
 418                 }
 419         }
 420         /* We accept everything at this stage. */
 421         return 0;
 422 }
 423
 424 void __init parse_early_options(char *cmdline)
 425 {
 426         parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
 427 }
 428
 429 /* Arch code calls this early on, or if not, just before other parsing. */
 430 void __init parse_early_param(void)
 431 {
 432         static __initdata int done = 0;
 433         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 434
 435         if (done)
 436                 return;
 437
 438         /* All fall through to do_early_param. */
 439         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 440         parse_early_options(tmp_cmdline);
 441         done = 1;
 442 }
 443
 444 /*
 445  *      Activate the first processor.
 446  */
 447
 448 static void __init boot_cpu_init(void)
 449 {
 450         int cpu = smp_processor_id();
 451         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 452         set_cpu_online(cpu, true);
 453         set_cpu_active(cpu, true);
 454         set_cpu_present(cpu, true);
 455         set_cpu_possible(cpu, true);
 456 }
 457
 458 void __init __weak smp_setup_processor_id(void)
 459 {
 460 }
 461
 462 # if THREAD_SIZE >= PAGE_SIZE
 463 void __init __weak thread_info_cache_init(void)
 464 {
 465 }
 466 #endif
 467
 468 /*
 469  * Set up kernel memory allocators
 470  */
 471 static void __init mm_init(void)
 472 {
 473         /*
 474          * page_cgroup requires contiguous pages,
 475          * bigger than MAX_ORDER unless SPARSEMEM.
 476          */
 477         page_cgroup_init_flatmem();
 478         mem_init();
 479         kmem_cache_init();
 480         percpu_init_late();
 481         pgtable_init();
 482         vmalloc_init();
 483 }
 484
 485 asmlinkage void __init start_kernel(void)
 486 {
 487         char * command_line;
 488         extern const struct kernel_param __start___param[], __stop___param[];
 489
 490         /*
 491          * Need to run as early as possible, to initialize the
 492          * lockdep hash:
 493          */
 494         lockdep_init();
 495         smp_setup_processor_id();
 496         debug_objects_early_init();
 497
 498         /*
 499          * Set up the the initial canary ASAP:
 500          */
 501         boot_init_stack_canary();
 502
 503         cgroup_init_early();
 504
 505         local_irq_disable();
 506         early_boot_irqs_disabled = true;
 507
 508 /*
 509  * Interrupts are still disabled. Do necessary setups, then
 510  * enable them
 511  */
 512         boot_cpu_init();
 513         page_address_init();
 514         pr_notice("%s", linux_banner);
 515         setup_arch(&command_line);
 516         mm_init_owner(&init_mm, &init_task);
 517         mm_init_cpumask(&init_mm);
 518         setup_command_line(command_line);
 519         setup_nr_cpu_ids();
 520         setup_per_cpu_areas();
 521         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 522
 523         build_all_zonelists(NULL, NULL);
 524         page_alloc_init();
 525
 526         pr_notice("Kernel command line: %s\n", boot_command_line);
 527         parse_early_param();
 528         parse_args("Booting kernel", static_command_line, __start___param,
 529                    __stop___param - __start___param,
 530                    -1, -1, &unknown_bootoption);
 531
 532         jump_label_init();
 533
 534         /*
 535          * These use large bootmem allocations and must precede
 536          * kmem_cache_init()
 537          */
 538         setup_log_buf(0);
 539         pidhash_init();
 540         vfs_caches_init_early();
 541         sort_main_extable();
 542         trap_init();
 543         mm_init();
 544
 545         /*
 546          * Set up the scheduler prior starting any interrupts (such as the
 547          * timer interrupt). Full topology setup happens at smp_init()
 548          * time - but meanwhile we still have a functioning scheduler.
 549          */
 550         sched_init();
 551         /*
 552          * Disable preemption - early bootup scheduling is extremely
 553          * fragile until we cpu_idle() for the first time.
 554          */
 555         preempt_disable();
 556         if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
 557                 local_irq_disable();
 558         idr_init_cache();
 559         rcu_init();
 560         tick_nohz_init();
 561         context_tracking_init();
 562         radix_tree_init();
 563         /* init some links before init_ISA_irqs() */
 564         early_irq_init();
 565         init_IRQ();
 566         tick_init();
 567         init_timers();
 568         hrtimers_init();
 569         softirq_init();
 570         timekeeping_init();
 571         time_init();
 572         sched_clock_postinit();
 573         perf_event_init();
 574         profile_init();
 575         call_function_init();
 576         WARN(!irqs_disabled(), "Interrupts were enabled early\n");
 577         early_boot_irqs_disabled = false;
 578         local_irq_enable();
 579
 580         kmem_cache_init_late();
 581
 582         /*
 583          * HACK ALERT! This is early. We're enabling the console before
 584          * we've done PCI setups etc, and console_init() must be aware of
 585          * this. But we do want output early, in case something goes wrong.
 586          */
 587         console_init();
 588         if (panic_later)
 589                 panic(panic_later, panic_param);
 590
 591         lockdep_info();
 592
 593         /*
 594          * Need to run this when irqs are enabled, because it wants
 595          * to self-test [hard/soft]-irqs on/off lock inversion bugs
 596          * too:
 597          */
 598         locking_selftest();
 599
 600 #ifdef CONFIG_BLK_DEV_INITRD
 601         if (initrd_start && !initrd_below_start_ok &&
 602             page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 603                 pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
 604                     page_to_pfn(virt_to_page((void *)initrd_start)),
 605                     min_low_pfn);
 606                 initrd_start = 0;
 607         }
 608 #endif
 609         page_cgroup_init();
 610         debug_objects_mem_init();
 611         kmemleak_init();
 612         setup_per_cpu_pageset();
 613         numa_policy_init();
 614         if (late_time_init)
 615                 late_time_init();
 616         sched_clock_init();
 617         calibrate_delay();
 618         pidmap_init();
 619         anon_vma_init();
 620 #ifdef CONFIG_X86
 621         if (efi_enabled(EFI_RUNTIME_SERVICES))
 622                 efi_enter_virtual_mode();
 623 #endif
 624         thread_info_cache_init();
 625         cred_init();
 626         fork_init(totalram_pages);
 627         proc_caches_init();
 628         buffer_init();
 629         key_init();
 630         security_init();
 631         dbg_late_init();
 632         vfs_caches_init(totalram_pages);
 633         signals_init();
 634         /* rootfs populating might need page-writeback */
 635         page_writeback_init();
 636 #ifdef CONFIG_PROC_FS
 637         proc_root_init();
 638 #endif
 639         cgroup_init();
 640         cpuset_init();
 641         taskstats_init_early();
 642         delayacct_init();
 643
 644         check_bugs();
 645
 646         acpi_early_init(); /* before LAPIC and SMP init */
 647         sfi_init_late();
 648
 649         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 650                 efi_late_init();
 651                 efi_free_boot_services();
 652         }
 653
 654         ftrace_init();
 655
 656         /* Do the rest non-__init'ed, we're now alive */
 657         rest_init();
 658 }
 659
 660 /* Call all constructor functions linked into the kernel. */
 661 static void __init do_ctors(void)
 662 {
 663 #ifdef CONFIG_CONSTRUCTORS
 664         ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
 665
 666         for (; fn < (ctor_fn_t *) __ctors_end; fn++)
 667                 (*fn)();
 668 #endif
 669 }
 670
 671 bool initcall_debug;
 672 core_param(initcall_debug, initcall_debug, bool, 0644);
 673
 674 static int __init_or_module do_one_initcall_debug(initcall_t fn)
 675 {
 676         ktime_t calltime, delta, rettime;
 677         unsigned long long duration;
 678         int ret;
 679
 680         pr_debug("calling  %pF @ %i\n", fn, task_pid_nr(current));
 681         calltime = ktime_get();
 682         ret = fn();
 683         rettime = ktime_get();
 684         delta = ktime_sub(rettime, calltime);
 685         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 686         pr_debug("initcall %pF returned %d after %lld usecs\n",
 687                  fn, ret, duration);
 688
 689         return ret;
 690 }
 691
 692 int __init_or_module do_one_initcall(initcall_t fn)
 693 {
 694         int count = preempt_count();
 695         int ret;
 696         char msgbuf[64];
 697
 698         if (initcall_debug)
 699                 ret = do_one_initcall_debug(fn);
 700         else
 701                 ret = fn();
 702
 703         msgbuf[0] = 0;
 704
 705         if (preempt_count() != count) {
 706                 sprintf(msgbuf, "preemption imbalance ");
 707                 preempt_count_set(count);
 708         }
 709         if (irqs_disabled()) {
 710                 strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 711                 local_irq_enable();
 712         }
 713         WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
 714
 715         return ret;
 716 }
 717
 718
 719 extern initcall_t __initcall_start[];
 720 extern initcall_t __initcall0_start[];
 721 extern initcall_t __initcall1_start[];
 722 extern initcall_t __initcall2_start[];
 723 extern initcall_t __initcall3_start[];
 724 extern initcall_t __initcall4_start[];
 725 extern initcall_t __initcall5_start[];
 726 extern initcall_t __initcall6_start[];
 727 extern initcall_t __initcall7_start[];
 728 extern initcall_t __initcall_end[];
 729
 730 static initcall_t *initcall_levels[] __initdata = {
 731         __initcall0_start,
 732         __initcall1_start,
 733         __initcall2_start,
 734         __initcall3_start,
 735         __initcall4_start,
 736         __initcall5_start,
 737         __initcall6_start,
 738         __initcall7_start,
 739         __initcall_end,
 740 };
 741
 742 /* Keep these in sync with initcalls in include/linux/init.h */
 743 static char *initcall_level_names[] __initdata = {
 744         "early",
 745         "core",
 746         "postcore",
 747         "arch",
 748         "subsys",
 749         "fs",
 750         "device",
 751         "late",
 752 };
 753
 754 static void __init do_initcall_level(int level)
 755 {
 756         extern const struct kernel_param __start___param[], __stop___param[];
 757         initcall_t *fn;
 758
 759         strcpy(initcall_command_line, saved_command_line);
 760         parse_args(initcall_level_names[level],
 761                    initcall_command_line, __start___param,
 762                    __stop___param - __start___param,
 763                    level, level,
 764                    &repair_env_string);
 765
 766         for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
 767                 do_one_initcall(*fn);
 768 }
 769
 770 static void __init do_initcalls(void)
 771 {
 772         int level;
 773
 774         for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
 775                 do_initcall_level(level);
 776 }
 777
 778 /*
 779  * Ok, the machine is now initialized. None of the devices
 780  * have been touched yet, but the CPU subsystem is up and
 781  * running, and memory and process management works.
 782  *
 783  * Now we can finally start doing some real work..
 784  */
 785 static void __init do_basic_setup(void)
 786 {
 787         cpuset_init_smp();
 788         usermodehelper_init();
 789         shmem_init();
 790         driver_init();
 791         init_irq_proc();
 792         do_ctors();
 793         usermodehelper_enable();
 794         do_initcalls();
 795         random_int_secret_init();
 796 }
 797
 798 static void __init do_pre_smp_initcalls(void)
 799 {
 800         initcall_t *fn;
 801
 802         for (fn = __initcall_start; fn < __initcall0_start; fn++)
 803                 do_one_initcall(*fn);
 804 }
 805
 806 /*
 807  * This function requests modules which should be loaded by default and is
 808  * called twice right after initrd is mounted and right before init is
 809  * exec'd.  If such modules are on either initrd or rootfs, they will be
 810  * loaded before control is passed to userland.
 811  */
 812 void __init load_default_modules(void)
 813 {
 814         load_default_elevator_module();
 815 }
 816
 817 static int run_init_process(const char *init_filename)
 818 {
 819         argv_init[0] = init_filename;
 820         return do_execve(init_filename,
 821                 (const char __user *const __user *)argv_init,
 822                 (const char __user *const __user *)envp_init);
 823 }
 824
 825 static int try_to_run_init_process(const char *init_filename)
 826 {
 827         int ret;
 828
 829         ret = run_init_process(init_filename);
 830
 831         if (ret && ret != -ENOENT) {
 832                 pr_err("Starting init: %s exists but couldn't execute it (error %d)\n",
 833                        init_filename, ret);
 834         }
 835
 836         return ret;
 837 }
 838
 839 static noinline void __init kernel_init_freeable(void);
 840
 841 static int __ref kernel_init(void *unused)
 842 {
 843         int ret;
 844
 845         kernel_init_freeable();
 846         /* need to finish all async __init code before freeing the memory */
 847         async_synchronize_full();
 848         free_initmem();
 849         mark_rodata_ro();
 850         system_state = SYSTEM_RUNNING;
 851         numa_default_policy();
 852
 853         flush_delayed_fput();
 854
 855         if (ramdisk_execute_command) {
 856                 ret = run_init_process(ramdisk_execute_command);
 857                 if (!ret)
 858                         return 0;
 859                 pr_err("Failed to execute %s (error %d)\n",
 860                        ramdisk_execute_command, ret);
 861         }
 862
 863         /*
 864          * We try each of these until one succeeds.
 865          *
 866          * The Bourne shell can be used instead of init if we are
 867          * trying to recover a really broken machine.
 868          */
 869         if (execute_command) {
 870                 ret = run_init_process(execute_command);
 871                 if (!ret)
 872                         return 0;
 873                 pr_err("Failed to execute %s (error %d).  Attempting defaults...\n",
 874                         execute_command, ret);
 875         }
 876         if (!try_to_run_init_process("/sbin/init") ||
 877             !try_to_run_init_process("/etc/init") ||
 878             !try_to_run_init_process("/bin/init") ||
 879             !try_to_run_init_process("/bin/sh"))
 880                 return 0;
 881
 882         panic("No working init found.  Try passing init= option to kernel. "
 883               "See Linux Documentation/init.txt for guidance.");
 884 }
 885
 886 static noinline void __init kernel_init_freeable(void)
 887 {
 888         /*
 889          * Wait until kthreadd is all set-up.
 890          */
 891         wait_for_completion(&kthreadd_done);
 892
 893         /* Now the scheduler is fully set up and can do blocking allocations */
 894         gfp_allowed_mask = __GFP_BITS_MASK;
 895
 896         /*
 897          * init can allocate pages on any node
 898          */
 899         set_mems_allowed(node_states[N_MEMORY]);
 900         /*
 901          * init can run on any cpu.
 902          */
 903         set_cpus_allowed_ptr(current, cpu_all_mask);
 904
 905         cad_pid = task_pid(current);
 906
 907         smp_prepare_cpus(setup_max_cpus);
 908
 909         do_pre_smp_initcalls();
 910         lockup_detector_init();
 911
 912         smp_init();
 913         sched_init_smp();
 914
 915         do_basic_setup();
 916
 917         /* Open the /dev/console on the rootfs, this should never fail */
 918         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 919                 pr_err("Warning: unable to open an initial console.\n");
 920
 921         (void) sys_dup(0);
 922         (void) sys_dup(0);
 923         /*
 924          * check if there is an early userspace init.  If yes, let it do all
 925          * the work
 926          */
 927
 928         if (!ramdisk_execute_command)
 929                 ramdisk_execute_command = "/init";
 930
 931         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 932                 ramdisk_execute_command = NULL;
 933                 prepare_namespace();
 934         }
 935
 936         /*
 937          * Ok, we have completed the initial bootup, and
 938          * we're essentially up and running. Get rid of the
 939          * initmem segments and start the user-mode stuff..
 940          */
 941
 942         /* rootfs is available now, try loading default modules */
 943         load_default_modules();
 944 }