linux/init/main.c
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   1/*
   2 *  linux/init/main.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 *
   6 *  GK 2/5/95  -  Changed to support mounting root fs via NFS
   7 *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
   8 *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
   9 *  Simplified starting of init:  Michael A. Griffith <grif@acm.org> 
  10 */
  11
  12#include <linux/types.h>
  13#include <linux/module.h>
  14#include <linux/proc_fs.h>
  15#include <linux/kernel.h>
  16#include <linux/syscalls.h>
  17#include <linux/stackprotector.h>
  18#include <linux/string.h>
  19#include <linux/ctype.h>
  20#include <linux/delay.h>
  21#include <linux/ioport.h>
  22#include <linux/init.h>
  23#include <linux/initrd.h>
  24#include <linux/bootmem.h>
  25#include <linux/acpi.h>
  26#include <linux/tty.h>
  27#include <linux/percpu.h>
  28#include <linux/kmod.h>
  29#include <linux/vmalloc.h>
  30#include <linux/kernel_stat.h>
  31#include <linux/start_kernel.h>
  32#include <linux/security.h>
  33#include <linux/smp.h>
  34#include <linux/profile.h>
  35#include <linux/rcupdate.h>
  36#include <linux/moduleparam.h>
  37#include <linux/kallsyms.h>
  38#include <linux/writeback.h>
  39#include <linux/cpu.h>
  40#include <linux/cpuset.h>
  41#include <linux/cgroup.h>
  42#include <linux/efi.h>
  43#include <linux/tick.h>
  44#include <linux/interrupt.h>
  45#include <linux/taskstats_kern.h>
  46#include <linux/delayacct.h>
  47#include <linux/unistd.h>
  48#include <linux/rmap.h>
  49#include <linux/mempolicy.h>
  50#include <linux/key.h>
  51#include <linux/buffer_head.h>
  52#include <linux/page_cgroup.h>
  53#include <linux/debug_locks.h>
  54#include <linux/debugobjects.h>
  55#include <linux/lockdep.h>
  56#include <linux/kmemleak.h>
  57#include <linux/pid_namespace.h>
  58#include <linux/device.h>
  59#include <linux/kthread.h>
  60#include <linux/sched.h>
  61#include <linux/signal.h>
  62#include <linux/idr.h>
  63#include <linux/kgdb.h>
  64#include <linux/ftrace.h>
  65#include <linux/async.h>
  66#include <linux/kmemcheck.h>
  67#include <linux/sfi.h>
  68#include <linux/shmem_fs.h>
  69#include <linux/slab.h>
  70#include <linux/perf_event.h>
  71
  72#include <asm/io.h>
  73#include <asm/bugs.h>
  74#include <asm/setup.h>
  75#include <asm/sections.h>
  76#include <asm/cacheflush.h>
  77
  78#ifdef CONFIG_X86_LOCAL_APIC
  79#include <asm/smp.h>
  80#endif
  81
  82static int kernel_init(void *);
  83
  84extern void init_IRQ(void);
  85extern void fork_init(unsigned long);
  86extern void mca_init(void);
  87extern void sbus_init(void);
  88extern void prio_tree_init(void);
  89extern void radix_tree_init(void);
  90#ifndef CONFIG_DEBUG_RODATA
  91static inline void mark_rodata_ro(void) { }
  92#endif
  93
  94#ifdef CONFIG_TC
  95extern void tc_init(void);
  96#endif
  97
  98/*
  99 * Debug helper: via this flag we know that we are in 'early bootup code'
 100 * where only the boot processor is running with IRQ disabled.  This means
 101 * two things - IRQ must not be enabled before the flag is cleared and some
 102 * operations which are not allowed with IRQ disabled are allowed while the
 103 * flag is set.
 104 */
 105bool early_boot_irqs_disabled __read_mostly;
 106
 107enum system_states system_state __read_mostly;
 108EXPORT_SYMBOL(system_state);
 109
 110/*
 111 * Boot command-line arguments
 112 */
 113#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
 114#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
 115
 116extern void time_init(void);
 117/* Default late time init is NULL. archs can override this later. */
 118void (*__initdata late_time_init)(void);
 119extern void softirq_init(void);
 120
 121/* Untouched command line saved by arch-specific code. */
 122char __initdata boot_command_line[COMMAND_LINE_SIZE];
 123/* Untouched saved command line (eg. for /proc) */
 124char *saved_command_line;
 125/* Command line for parameter parsing */
 126static char *static_command_line;
 127
 128static char *execute_command;
 129static char *ramdisk_execute_command;
 130
 131/*
 132 * If set, this is an indication to the drivers that reset the underlying
 133 * device before going ahead with the initialization otherwise driver might
 134 * rely on the BIOS and skip the reset operation.
 135 *
 136 * This is useful if kernel is booting in an unreliable environment.
 137 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 138 * skipped and devices will be in unknown state.
 139 */
 140unsigned int reset_devices;
 141EXPORT_SYMBOL(reset_devices);
 142
 143static int __init set_reset_devices(char *str)
 144{
 145        reset_devices = 1;
 146        return 1;
 147}
 148
 149__setup("reset_devices", set_reset_devices);
 150
 151static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 152const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 153static const char *panic_later, *panic_param;
 154
 155extern const struct obs_kernel_param __setup_start[], __setup_end[];
 156
 157static int __init obsolete_checksetup(char *line)
 158{
 159        const struct obs_kernel_param *p;
 160        int had_early_param = 0;
 161
 162        p = __setup_start;
 163        do {
 164                int n = strlen(p->str);
 165                if (parameqn(line, p->str, n)) {
 166                        if (p->early) {
 167                                /* Already done in parse_early_param?
 168                                 * (Needs exact match on param part).
 169                                 * Keep iterating, as we can have early
 170                                 * params and __setups of same names 8( */
 171                                if (line[n] == '\0' || line[n] == '=')
 172                                        had_early_param = 1;
 173                        } else if (!p->setup_func) {
 174                                printk(KERN_WARNING "Parameter %s is obsolete,"
 175                                       " ignored\n", p->str);
 176                                return 1;
 177                        } else if (p->setup_func(line + n))
 178                                return 1;
 179                }
 180                p++;
 181        } while (p < __setup_end);
 182
 183        return had_early_param;
 184}
 185
 186/*
 187 * This should be approx 2 Bo*oMips to start (note initial shift), and will
 188 * still work even if initially too large, it will just take slightly longer
 189 */
 190unsigned long loops_per_jiffy = (1<<12);
 191
 192EXPORT_SYMBOL(loops_per_jiffy);
 193
 194static int __init debug_kernel(char *str)
 195{
 196        console_loglevel = 10;
 197        return 0;
 198}
 199
 200static int __init quiet_kernel(char *str)
 201{
 202        console_loglevel = 4;
 203        return 0;
 204}
 205
 206early_param("debug", debug_kernel);
 207early_param("quiet", quiet_kernel);
 208
 209static int __init loglevel(char *str)
 210{
 211        int newlevel;
 212
 213        /*
 214         * Only update loglevel value when a correct setting was passed,
 215         * to prevent blind crashes (when loglevel being set to 0) that
 216         * are quite hard to debug
 217         */
 218        if (get_option(&str, &newlevel)) {
 219                console_loglevel = newlevel;
 220                return 0;
 221        }
 222
 223        return -EINVAL;
 224}
 225
 226early_param("loglevel", loglevel);
 227
 228/* Change NUL term back to "=", to make "param" the whole string. */
 229static int __init repair_env_string(char *param, char *val, const char *unused)
 230{
 231        if (val) {
 232                /* param=val or param="val"? */
 233                if (val == param+strlen(param)+1)
 234                        val[-1] = '=';
 235                else if (val == param+strlen(param)+2) {
 236                        val[-2] = '=';
 237                        memmove(val-1, val, strlen(val)+1);
 238                        val--;
 239                } else
 240                        BUG();
 241        }
 242        return 0;
 243}
 244
 245/*
 246 * Unknown boot options get handed to init, unless they look like
 247 * unused parameters (modprobe will find them in /proc/cmdline).
 248 */
 249static int __init unknown_bootoption(char *param, char *val, const char *unused)
 250{
 251        repair_env_string(param, val, unused);
 252
 253        /* Handle obsolete-style parameters */
 254        if (obsolete_checksetup(param))
 255                return 0;
 256
 257        /* Unused module parameter. */
 258        if (strchr(param, '.') && (!val || strchr(param, '.') < val))
 259                return 0;
 260
 261        if (panic_later)
 262                return 0;
 263
 264        if (val) {
 265                /* Environment option */
 266                unsigned int i;
 267                for (i = 0; envp_init[i]; i++) {
 268                        if (i == MAX_INIT_ENVS) {
 269                                panic_later = "Too many boot env vars at `%s'";
 270                                panic_param = param;
 271                        }
 272                        if (!strncmp(param, envp_init[i], val - param))
 273                                break;
 274                }
 275                envp_init[i] = param;
 276        } else {
 277                /* Command line option */
 278                unsigned int i;
 279                for (i = 0; argv_init[i]; i++) {
 280                        if (i == MAX_INIT_ARGS) {
 281                                panic_later = "Too many boot init vars at `%s'";
 282                                panic_param = param;
 283                        }
 284                }
 285                argv_init[i] = param;
 286        }
 287        return 0;
 288}
 289
 290static int __init init_setup(char *str)
 291{
 292        unsigned int i;
 293
 294        execute_command = str;
 295        /*
 296         * In case LILO is going to boot us with default command line,
 297         * it prepends "auto" before the whole cmdline which makes
 298         * the shell think it should execute a script with such name.
 299         * So we ignore all arguments entered _before_ init=... [MJ]
 300         */
 301        for (i = 1; i < MAX_INIT_ARGS; i++)
 302                argv_init[i] = NULL;
 303        return 1;
 304}
 305__setup("init=", init_setup);
 306
 307static int __init rdinit_setup(char *str)
 308{
 309        unsigned int i;
 310
 311        ramdisk_execute_command = str;
 312        /* See "auto" comment in init_setup */
 313        for (i = 1; i < MAX_INIT_ARGS; i++)
 314                argv_init[i] = NULL;
 315        return 1;
 316}
 317__setup("rdinit=", rdinit_setup);
 318
 319#ifndef CONFIG_SMP
 320static const unsigned int setup_max_cpus = NR_CPUS;
 321#ifdef CONFIG_X86_LOCAL_APIC
 322static void __init smp_init(void)
 323{
 324        APIC_init_uniprocessor();
 325}
 326#else
 327#define smp_init()      do { } while (0)
 328#endif
 329
 330static inline void setup_nr_cpu_ids(void) { }
 331static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 332#endif
 333
 334/*
 335 * We need to store the untouched command line for future reference.
 336 * We also need to store the touched command line since the parameter
 337 * parsing is performed in place, and we should allow a component to
 338 * store reference of name/value for future reference.
 339 */
 340static void __init setup_command_line(char *command_line)
 341{
 342        saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 343        static_command_line = alloc_bootmem(strlen (command_line)+1);
 344        strcpy (saved_command_line, boot_command_line);
 345        strcpy (static_command_line, command_line);
 346}
 347
 348/*
 349 * We need to finalize in a non-__init function or else race conditions
 350 * between the root thread and the init thread may cause start_kernel to
 351 * be reaped by free_initmem before the root thread has proceeded to
 352 * cpu_idle.
 353 *
 354 * gcc-3.4 accidentally inlines this function, so use noinline.
 355 */
 356
 357static __initdata DECLARE_COMPLETION(kthreadd_done);
 358
 359static noinline void __init_refok rest_init(void)
 360{
 361        int pid;
 362
 363        rcu_scheduler_starting();
 364        /*
 365         * We need to spawn init first so that it obtains pid 1, however
 366         * the init task will end up wanting to create kthreads, which, if
 367         * we schedule it before we create kthreadd, will OOPS.
 368         */
 369        kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 370        numa_default_policy();
 371        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 372        rcu_read_lock();
 373        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 374        rcu_read_unlock();
 375        complete(&kthreadd_done);
 376
 377        /*
 378         * The boot idle thread must execute schedule()
 379         * at least once to get things moving:
 380         */
 381        init_idle_bootup_task(current);
 382        schedule_preempt_disabled();
 383        /* Call into cpu_idle with preempt disabled */
 384        cpu_idle();
 385}
 386
 387/* Check for early params. */
 388static int __init do_early_param(char *param, char *val, const char *unused)
 389{
 390        const struct obs_kernel_param *p;
 391
 392        for (p = __setup_start; p < __setup_end; p++) {
 393                if ((p->early && parameq(param, p->str)) ||
 394                    (strcmp(param, "console") == 0 &&
 395                     strcmp(p->str, "earlycon") == 0)
 396                ) {
 397                        if (p->setup_func(val) != 0)
 398                                printk(KERN_WARNING
 399                                       "Malformed early option '%s'\n", param);
 400                }
 401        }
 402        /* We accept everything at this stage. */
 403        return 0;
 404}
 405
 406void __init parse_early_options(char *cmdline)
 407{
 408        parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
 409}
 410
 411/* Arch code calls this early on, or if not, just before other parsing. */
 412void __init parse_early_param(void)
 413{
 414        static __initdata int done = 0;
 415        static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 416
 417        if (done)
 418                return;
 419
 420        /* All fall through to do_early_param. */
 421        strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 422        parse_early_options(tmp_cmdline);
 423        done = 1;
 424}
 425
 426/*
 427 *      Activate the first processor.
 428 */
 429
 430static void __init boot_cpu_init(void)
 431{
 432        int cpu = smp_processor_id();
 433        /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 434        set_cpu_online(cpu, true);
 435        set_cpu_active(cpu, true);
 436        set_cpu_present(cpu, true);
 437        set_cpu_possible(cpu, true);
 438}
 439
 440void __init __weak smp_setup_processor_id(void)
 441{
 442}
 443
 444void __init __weak thread_info_cache_init(void)
 445{
 446}
 447
 448/*
 449 * Set up kernel memory allocators
 450 */
 451static void __init mm_init(void)
 452{
 453        /*
 454         * page_cgroup requires contiguous pages,
 455         * bigger than MAX_ORDER unless SPARSEMEM.
 456         */
 457        page_cgroup_init_flatmem();
 458        mem_init();
 459        kmem_cache_init();
 460        percpu_init_late();
 461        pgtable_cache_init();
 462        vmalloc_init();
 463}
 464
 465asmlinkage void __init start_kernel(void)
 466{
 467        char * command_line;
 468        extern const struct kernel_param __start___param[], __stop___param[];
 469
 470        /*
 471         * Need to run as early as possible, to initialize the
 472         * lockdep hash:
 473         */
 474        lockdep_init();
 475        smp_setup_processor_id();
 476        debug_objects_early_init();
 477
 478        /*
 479         * Set up the the initial canary ASAP:
 480         */
 481        boot_init_stack_canary();
 482
 483        cgroup_init_early();
 484
 485        local_irq_disable();
 486        early_boot_irqs_disabled = true;
 487
 488/*
 489 * Interrupts are still disabled. Do necessary setups, then
 490 * enable them
 491 */
 492        tick_init();
 493        boot_cpu_init();
 494        page_address_init();
 495        printk(KERN_NOTICE "%s", linux_banner);
 496        setup_arch(&command_line);
 497        mm_init_owner(&init_mm, &init_task);
 498        mm_init_cpumask(&init_mm);
 499        setup_command_line(command_line);
 500        setup_nr_cpu_ids();
 501        setup_per_cpu_areas();
 502        smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 503
 504        build_all_zonelists(NULL);
 505        page_alloc_init();
 506
 507        printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
 508        parse_early_param();
 509        parse_args("Booting kernel", static_command_line, __start___param,
 510                   __stop___param - __start___param,
 511                   -1, -1, &unknown_bootoption);
 512
 513        jump_label_init();
 514
 515        /*
 516         * These use large bootmem allocations and must precede
 517         * kmem_cache_init()
 518         */
 519        setup_log_buf(0);
 520        pidhash_init();
 521        vfs_caches_init_early();
 522        sort_main_extable();
 523        trap_init();
 524        mm_init();
 525
 526        /*
 527         * Set up the scheduler prior starting any interrupts (such as the
 528         * timer interrupt). Full topology setup happens at smp_init()
 529         * time - but meanwhile we still have a functioning scheduler.
 530         */
 531        sched_init();
 532        /*
 533         * Disable preemption - early bootup scheduling is extremely
 534         * fragile until we cpu_idle() for the first time.
 535         */
 536        preempt_disable();
 537        if (!irqs_disabled()) {
 538                printk(KERN_WARNING "start_kernel(): bug: interrupts were "
 539                                "enabled *very* early, fixing it\n");
 540                local_irq_disable();
 541        }
 542        idr_init_cache();
 543        perf_event_init();
 544        rcu_init();
 545        radix_tree_init();
 546        /* init some links before init_ISA_irqs() */
 547        early_irq_init();
 548        init_IRQ();
 549        prio_tree_init();
 550        init_timers();
 551        hrtimers_init();
 552        softirq_init();
 553        timekeeping_init();
 554        time_init();
 555        profile_init();
 556        call_function_init();
 557        if (!irqs_disabled())
 558                printk(KERN_CRIT "start_kernel(): bug: interrupts were "
 559                                 "enabled early\n");
 560        early_boot_irqs_disabled = false;
 561        local_irq_enable();
 562
 563        kmem_cache_init_late();
 564
 565        /*
 566         * HACK ALERT! This is early. We're enabling the console before
 567         * we've done PCI setups etc, and console_init() must be aware of
 568         * this. But we do want output early, in case something goes wrong.
 569         */
 570        console_init();
 571        if (panic_later)
 572                panic(panic_later, panic_param);
 573
 574        lockdep_info();
 575
 576        /*
 577         * Need to run this when irqs are enabled, because it wants
 578         * to self-test [hard/soft]-irqs on/off lock inversion bugs
 579         * too:
 580         */
 581        locking_selftest();
 582
 583#ifdef CONFIG_BLK_DEV_INITRD
 584        if (initrd_start && !initrd_below_start_ok &&
 585            page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 586                printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
 587                    "disabling it.\n",
 588                    page_to_pfn(virt_to_page((void *)initrd_start)),
 589                    min_low_pfn);
 590                initrd_start = 0;
 591        }
 592#endif
 593        page_cgroup_init();
 594        debug_objects_mem_init();
 595        kmemleak_init();
 596        setup_per_cpu_pageset();
 597        numa_policy_init();
 598        if (late_time_init)
 599                late_time_init();
 600        sched_clock_init();
 601        calibrate_delay();
 602        pidmap_init();
 603        anon_vma_init();
 604#ifdef CONFIG_X86
 605        if (efi_enabled)
 606                efi_enter_virtual_mode();
 607#endif
 608        thread_info_cache_init();
 609        cred_init();
 610        fork_init(totalram_pages);
 611        proc_caches_init();
 612        buffer_init();
 613        key_init();
 614        security_init();
 615        dbg_late_init();
 616        vfs_caches_init(totalram_pages);
 617        signals_init();
 618        /* rootfs populating might need page-writeback */
 619        page_writeback_init();
 620#ifdef CONFIG_PROC_FS
 621        proc_root_init();
 622#endif
 623        cgroup_init();
 624        cpuset_init();
 625        taskstats_init_early();
 626        delayacct_init();
 627
 628        check_bugs();
 629
 630        acpi_early_init(); /* before LAPIC and SMP init */
 631        sfi_init_late();
 632
 633        ftrace_init();
 634
 635        /* Do the rest non-__init'ed, we're now alive */
 636        rest_init();
 637}
 638
 639/* Call all constructor functions linked into the kernel. */
 640static void __init do_ctors(void)
 641{
 642#ifdef CONFIG_CONSTRUCTORS
 643        ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
 644
 645        for (; fn < (ctor_fn_t *) __ctors_end; fn++)
 646                (*fn)();
 647#endif
 648}
 649
 650bool initcall_debug;
 651core_param(initcall_debug, initcall_debug, bool, 0644);
 652
 653static char msgbuf[64];
 654
 655static int __init_or_module do_one_initcall_debug(initcall_t fn)
 656{
 657        ktime_t calltime, delta, rettime;
 658        unsigned long long duration;
 659        int ret;
 660
 661        printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
 662        calltime = ktime_get();
 663        ret = fn();
 664        rettime = ktime_get();
 665        delta = ktime_sub(rettime, calltime);
 666        duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 667        printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn,
 668                ret, duration);
 669
 670        return ret;
 671}
 672
 673int __init_or_module do_one_initcall(initcall_t fn)
 674{
 675        int count = preempt_count();
 676        int ret;
 677
 678        if (initcall_debug)
 679                ret = do_one_initcall_debug(fn);
 680        else
 681                ret = fn();
 682
 683        msgbuf[0] = 0;
 684
 685        if (ret && ret != -ENODEV && initcall_debug)
 686                sprintf(msgbuf, "error code %d ", ret);
 687
 688        if (preempt_count() != count) {
 689                strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
 690                preempt_count() = count;
 691        }
 692        if (irqs_disabled()) {
 693                strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 694                local_irq_enable();
 695        }
 696        if (msgbuf[0]) {
 697                printk("initcall %pF returned with %s\n", fn, msgbuf);
 698        }
 699
 700        return ret;
 701}
 702
 703
 704extern initcall_t __initcall_start[];
 705extern initcall_t __initcall0_start[];
 706extern initcall_t __initcall1_start[];
 707extern initcall_t __initcall2_start[];
 708extern initcall_t __initcall3_start[];
 709extern initcall_t __initcall4_start[];
 710extern initcall_t __initcall5_start[];
 711extern initcall_t __initcall6_start[];
 712extern initcall_t __initcall7_start[];
 713extern initcall_t __initcall_end[];
 714
 715static initcall_t *initcall_levels[] __initdata = {
 716        __initcall0_start,
 717        __initcall1_start,
 718        __initcall2_start,
 719        __initcall3_start,
 720        __initcall4_start,
 721        __initcall5_start,
 722        __initcall6_start,
 723        __initcall7_start,
 724        __initcall_end,
 725};
 726
 727static char *initcall_level_names[] __initdata = {
 728        "early",
 729        "core",
 730        "postcore",
 731        "arch",
 732        "subsys",
 733        "fs",
 734        "device",
 735        "late",
 736};
 737
 738static void __init do_initcall_level(int level)
 739{
 740        extern const struct kernel_param __start___param[], __stop___param[];
 741        initcall_t *fn;
 742
 743        strcpy(static_command_line, saved_command_line);
 744        parse_args(initcall_level_names[level],
 745                   static_command_line, __start___param,
 746                   __stop___param - __start___param,
 747                   level, level,
 748                   &repair_env_string);
 749
 750        for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
 751                do_one_initcall(*fn);
 752}
 753
 754static void __init do_initcalls(void)
 755{
 756        int level;
 757
 758        for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
 759                do_initcall_level(level);
 760}
 761
 762/*
 763 * Ok, the machine is now initialized. None of the devices
 764 * have been touched yet, but the CPU subsystem is up and
 765 * running, and memory and process management works.
 766 *
 767 * Now we can finally start doing some real work..
 768 */
 769static void __init do_basic_setup(void)
 770{
 771        cpuset_init_smp();
 772        usermodehelper_init();
 773        shmem_init();
 774        driver_init();
 775        init_irq_proc();
 776        do_ctors();
 777        usermodehelper_enable();
 778        do_initcalls();
 779}
 780
 781static void __init do_pre_smp_initcalls(void)
 782{
 783        initcall_t *fn;
 784
 785        for (fn = __initcall_start; fn < __initcall0_start; fn++)
 786                do_one_initcall(*fn);
 787}
 788
 789static void run_init_process(const char *init_filename)
 790{
 791        argv_init[0] = init_filename;
 792        kernel_execve(init_filename, argv_init, envp_init);
 793}
 794
 795/* This is a non __init function. Force it to be noinline otherwise gcc
 796 * makes it inline to init() and it becomes part of init.text section
 797 */
 798static noinline int init_post(void)
 799{
 800        /* need to finish all async __init code before freeing the memory */
 801        async_synchronize_full();
 802        free_initmem();
 803        mark_rodata_ro();
 804        system_state = SYSTEM_RUNNING;
 805        numa_default_policy();
 806
 807
 808        current->signal->flags |= SIGNAL_UNKILLABLE;
 809
 810        if (ramdisk_execute_command) {
 811                run_init_process(ramdisk_execute_command);
 812                printk(KERN_WARNING "Failed to execute %s\n",
 813                                ramdisk_execute_command);
 814        }
 815
 816        /*
 817         * We try each of these until one succeeds.
 818         *
 819         * The Bourne shell can be used instead of init if we are
 820         * trying to recover a really broken machine.
 821         */
 822        if (execute_command) {
 823                run_init_process(execute_command);
 824                printk(KERN_WARNING "Failed to execute %s.  Attempting "
 825                                        "defaults...\n", execute_command);
 826        }
 827        run_init_process("/sbin/init");
 828        run_init_process("/etc/init");
 829        run_init_process("/bin/init");
 830        run_init_process("/bin/sh");
 831
 832        panic("No init found.  Try passing init= option to kernel. "
 833              "See Linux Documentation/init.txt for guidance.");
 834}
 835
 836static int __init kernel_init(void * unused)
 837{
 838        /*
 839         * Wait until kthreadd is all set-up.
 840         */
 841        wait_for_completion(&kthreadd_done);
 842
 843        /* Now the scheduler is fully set up and can do blocking allocations */
 844        gfp_allowed_mask = __GFP_BITS_MASK;
 845
 846        /*
 847         * init can allocate pages on any node
 848         */
 849        set_mems_allowed(node_states[N_HIGH_MEMORY]);
 850        /*
 851         * init can run on any cpu.
 852         */
 853        set_cpus_allowed_ptr(current, cpu_all_mask);
 854
 855        cad_pid = task_pid(current);
 856
 857        smp_prepare_cpus(setup_max_cpus);
 858
 859        do_pre_smp_initcalls();
 860        lockup_detector_init();
 861
 862        smp_init();
 863        sched_init_smp();
 864
 865        do_basic_setup();
 866
 867        /* Open the /dev/console on the rootfs, this should never fail */
 868        if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 869                printk(KERN_WARNING "Warning: unable to open an initial console.\n");
 870
 871        (void) sys_dup(0);
 872        (void) sys_dup(0);
 873        /*
 874         * check if there is an early userspace init.  If yes, let it do all
 875         * the work
 876         */
 877
 878        if (!ramdisk_execute_command)
 879                ramdisk_execute_command = "/init";
 880
 881        if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 882                ramdisk_execute_command = NULL;
 883                prepare_namespace();
 884        }
 885
 886        /*
 887         * Ok, we have completed the initial bootup, and
 888         * we're essentially up and running. Get rid of the
 889         * initmem segments and start the user-mode stuff..
 890         */
 891
 892        init_post();
 893        return 0;
 894}
 895
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