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#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
  91static int kernel_init(void *);
  92
  93extern void init_IRQ(void);
  94extern void fork_init(unsigned long);
  95extern void mca_init(void);
  96extern void sbus_init(void);
  97extern void radix_tree_init(void);
  98#ifndef CONFIG_DEBUG_RODATA
  99static inline void mark_rodata_ro(void) { }
 100#endif
 101
 102#ifdef CONFIG_TC
 103extern 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 */
 113bool early_boot_irqs_disabled __read_mostly;
 114
 115enum system_states system_state __read_mostly;
 116EXPORT_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
 124extern void time_init(void);
 125/* Default late time init is NULL. archs can override this later. */
 126void (*__initdata late_time_init)(void);
 127extern void softirq_init(void);
 128
 129/* Untouched command line saved by arch-specific code. */
 130char __initdata boot_command_line[COMMAND_LINE_SIZE];
 131/* Untouched saved command line (eg. for /proc) */
 132char *saved_command_line;
 133/* Command line for parameter parsing */
 134static char *static_command_line;
 135
 136static char *execute_command;
 137static char *ramdisk_execute_command;
 138
 139/*
 140 * If set, this is an indication to the drivers that reset the underlying
 141 * device before going ahead with the initialization otherwise driver might
 142 * rely on the BIOS and skip the reset operation.
 143 *
 144 * This is useful if kernel is booting in an unreliable environment.
 145 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
 146 * skipped and devices will be in unknown state.
 147 */
 148unsigned int reset_devices;
 149EXPORT_SYMBOL(reset_devices);
 150
 151static int __init set_reset_devices(char *str)
 152{
 153        reset_devices = 1;
 154        return 1;
 155}
 156
 157__setup("reset_devices", set_reset_devices);
 158
 159static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 160const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
 161static const char *panic_later, *panic_param;
 162
 163extern const struct obs_kernel_param __setup_start[], __setup_end[];
 164
 165static int __init obsolete_checksetup(char *line)
 166{
 167        const struct obs_kernel_param *p;
 168        int had_early_param = 0;
 169
 170        p = __setup_start;
 171        do {
 172                int n = strlen(p->str);
 173                if (parameqn(line, p->str, n)) {
 174                        if (p->early) {
 175                                /* Already done in parse_early_param?
 176                                 * (Needs exact match on param part).
 177                                 * Keep iterating, as we can have early
 178                                 * params and __setups of same names 8( */
 179                                if (line[n] == '\0' || line[n] == '=')
 180                                        had_early_param = 1;
 181                        } else if (!p->setup_func) {
 182                                pr_warn("Parameter %s is obsolete, ignored\n",
 183                                        p->str);
 184                                return 1;
 185                        } else if (p->setup_func(line + n))
 186                                return 1;
 187                }
 188                p++;
 189        } while (p < __setup_end);
 190
 191        return had_early_param;
 192}
 193
 194/*
 195 * This should be approx 2 Bo*oMips to start (note initial shift), and will
 196 * still work even if initially too large, it will just take slightly longer
 197 */
 198unsigned long loops_per_jiffy = (1<<12);
 199
 200EXPORT_SYMBOL(loops_per_jiffy);
 201
 202static int __init debug_kernel(char *str)
 203{
 204        console_loglevel = 10;
 205        return 0;
 206}
 207
 208static int __init quiet_kernel(char *str)
 209{
 210        console_loglevel = 4;
 211        return 0;
 212}
 213
 214early_param("debug", debug_kernel);
 215early_param("quiet", quiet_kernel);
 216
 217static int __init loglevel(char *str)
 218{
 219        int newlevel;
 220
 221        /*
 222         * Only update loglevel value when a correct setting was passed,
 223         * to prevent blind crashes (when loglevel being set to 0) that
 224         * are quite hard to debug
 225         */
 226        if (get_option(&str, &newlevel)) {
 227                console_loglevel = newlevel;
 228                return 0;
 229        }
 230
 231        return -EINVAL;
 232}
 233
 234early_param("loglevel", loglevel);
 235
 236/* Change NUL term back to "=", to make "param" the whole string. */
 237static int __init repair_env_string(char *param, char *val, const char *unused)
 238{
 239        if (val) {
 240                /* param=val or param="val"? */
 241                if (val == param+strlen(param)+1)
 242                        val[-1] = '=';
 243                else if (val == param+strlen(param)+2) {
 244                        val[-2] = '=';
 245                        memmove(val-1, val, strlen(val)+1);
 246                        val--;
 247                } else
 248                        BUG();
 249        }
 250        return 0;
 251}
 252
 253/*
 254 * Unknown boot options get handed to init, unless they look like
 255 * unused parameters (modprobe will find them in /proc/cmdline).
 256 */
 257static int __init unknown_bootoption(char *param, char *val, const char *unused)
 258{
 259        repair_env_string(param, val, unused);
 260
 261        /* Handle obsolete-style parameters */
 262        if (obsolete_checksetup(param))
 263                return 0;
 264
 265        /* Unused module parameter. */
 266        if (strchr(param, '.') && (!val || strchr(param, '.') < val))
 267                return 0;
 268
 269        if (panic_later)
 270                return 0;
 271
 272        if (val) {
 273                /* Environment option */
 274                unsigned int i;
 275                for (i = 0; envp_init[i]; i++) {
 276                        if (i == MAX_INIT_ENVS) {
 277                                panic_later = "Too many boot env vars at `%s'";
 278                                panic_param = param;
 279                        }
 280                        if (!strncmp(param, envp_init[i], val - param))
 281                                break;
 282                }
 283                envp_init[i] = param;
 284        } else {
 285                /* Command line option */
 286                unsigned int i;
 287                for (i = 0; argv_init[i]; i++) {
 288                        if (i == MAX_INIT_ARGS) {
 289                                panic_later = "Too many boot init vars at `%s'";
 290                                panic_param = param;
 291                        }
 292                }
 293                argv_init[i] = param;
 294        }
 295        return 0;
 296}
 297
 298static int __init init_setup(char *str)
 299{
 300        unsigned int i;
 301
 302        execute_command = str;
 303        /*
 304         * In case LILO is going to boot us with default command line,
 305         * it prepends "auto" before the whole cmdline which makes
 306         * the shell think it should execute a script with such name.
 307         * So we ignore all arguments entered _before_ init=... [MJ]
 308         */
 309        for (i = 1; i < MAX_INIT_ARGS; i++)
 310                argv_init[i] = NULL;
 311        return 1;
 312}
 313__setup("init=", init_setup);
 314
 315static int __init rdinit_setup(char *str)
 316{
 317        unsigned int i;
 318
 319        ramdisk_execute_command = str;
 320        /* See "auto" comment in init_setup */
 321        for (i = 1; i < MAX_INIT_ARGS; i++)
 322                argv_init[i] = NULL;
 323        return 1;
 324}
 325__setup("rdinit=", rdinit_setup);
 326
 327#ifndef CONFIG_SMP
 328static const unsigned int setup_max_cpus = NR_CPUS;
 329#ifdef CONFIG_X86_LOCAL_APIC
 330static void __init smp_init(void)
 331{
 332        APIC_init_uniprocessor();
 333}
 334#else
 335#define smp_init()      do { } while (0)
 336#endif
 337
 338static inline void setup_nr_cpu_ids(void) { }
 339static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 340#endif
 341
 342/*
 343 * We need to store the untouched command line for future reference.
 344 * We also need to store the touched command line since the parameter
 345 * parsing is performed in place, and we should allow a component to
 346 * store reference of name/value for future reference.
 347 */
 348static void __init setup_command_line(char *command_line)
 349{
 350        saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
 351        static_command_line = alloc_bootmem(strlen (command_line)+1);
 352        strcpy (saved_command_line, boot_command_line);
 353        strcpy (static_command_line, command_line);
 354}
 355
 356/*
 357 * We need to finalize in a non-__init function or else race conditions
 358 * between the root thread and the init thread may cause start_kernel to
 359 * be reaped by free_initmem before the root thread has proceeded to
 360 * cpu_idle.
 361 *
 362 * gcc-3.4 accidentally inlines this function, so use noinline.
 363 */
 364
 365static __initdata DECLARE_COMPLETION(kthreadd_done);
 366
 367static noinline void __init_refok rest_init(void)
 368{
 369        int pid;
 370
 371        rcu_scheduler_starting();
 372        /*
 373         * We need to spawn init first so that it obtains pid 1, however
 374         * the init task will end up wanting to create kthreads, which, if
 375         * we schedule it before we create kthreadd, will OOPS.
 376         */
 377        kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 378        numa_default_policy();
 379        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
 380        rcu_read_lock();
 381        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 382        rcu_read_unlock();
 383        complete(&kthreadd_done);
 384
 385        /*
 386         * The boot idle thread must execute schedule()
 387         * at least once to get things moving:
 388         */
 389        init_idle_bootup_task(current);
 390        schedule_preempt_disabled();
 391        /* Call into cpu_idle with preempt disabled */
 392        cpu_startup_entry(CPUHP_ONLINE);
 393}
 394
 395/* Check for early params. */
 396static int __init do_early_param(char *param, char *val, const char *unused)
 397{
 398        const struct obs_kernel_param *p;
 399
 400        for (p = __setup_start; p < __setup_end; p++) {
 401                if ((p->early && parameq(param, p->str)) ||
 402                    (strcmp(param, "console") == 0 &&
 403                     strcmp(p->str, "earlycon") == 0)
 404                ) {
 405                        if (p->setup_func(val) != 0)
 406                                pr_warn("Malformed early option '%s'\n", param);
 407                }
 408        }
 409        /* We accept everything at this stage. */
 410        return 0;
 411}
 412
 413void __init parse_early_options(char *cmdline)
 414{
 415        parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
 416}
 417
 418/* Arch code calls this early on, or if not, just before other parsing. */
 419void __init parse_early_param(void)
 420{
 421        static __initdata int done = 0;
 422        static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
 423
 424        if (done)
 425                return;
 426
 427        /* All fall through to do_early_param. */
 428        strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 429        parse_early_options(tmp_cmdline);
 430        done = 1;
 431}
 432
 433/*
 434 *      Activate the first processor.
 435 */
 436
 437static void __init boot_cpu_init(void)
 438{
 439        int cpu = smp_processor_id();
 440        /* Mark the boot cpu "present", "online" etc for SMP and UP case */
 441        set_cpu_online(cpu, true);
 442        set_cpu_active(cpu, true);
 443        set_cpu_present(cpu, true);
 444        set_cpu_possible(cpu, true);
 445}
 446
 447void __init __weak smp_setup_processor_id(void)
 448{
 449}
 450
 451# if THREAD_SIZE >= PAGE_SIZE
 452void __init __weak thread_info_cache_init(void)
 453{
 454}
 455#endif
 456
 457/*
 458 * Set up kernel memory allocators
 459 */
 460static void __init mm_init(void)
 461{
 462        /*
 463         * page_cgroup requires contiguous pages,
 464         * bigger than MAX_ORDER unless SPARSEMEM.
 465         */
 466        page_cgroup_init_flatmem();
 467        mem_init();
 468        kmem_cache_init();
 469        percpu_init_late();
 470        pgtable_cache_init();
 471        vmalloc_init();
 472}
 473
 474asmlinkage void __init start_kernel(void)
 475{
 476        char * command_line;
 477        extern const struct kernel_param __start___param[], __stop___param[];
 478
 479        /*
 480         * Need to run as early as possible, to initialize the
 481         * lockdep hash:
 482         */
 483        lockdep_init();
 484        smp_setup_processor_id();
 485        debug_objects_early_init();
 486
 487        /*
 488         * Set up the the initial canary ASAP:
 489         */
 490        boot_init_stack_canary();
 491
 492        cgroup_init_early();
 493
 494        local_irq_disable();
 495        early_boot_irqs_disabled = true;
 496
 497/*
 498 * Interrupts are still disabled. Do necessary setups, then
 499 * enable them
 500 */
 501        boot_cpu_init();
 502        page_address_init();
 503        pr_notice("%s", linux_banner);
 504        setup_arch(&command_line);
 505        mm_init_owner(&init_mm, &init_task);
 506        mm_init_cpumask(&init_mm);
 507        setup_command_line(command_line);
 508        setup_nr_cpu_ids();
 509        setup_per_cpu_areas();
 510        smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
 511
 512        build_all_zonelists(NULL, NULL);
 513        page_alloc_init();
 514
 515        pr_notice("Kernel command line: %s\n", boot_command_line);
 516        parse_early_param();
 517        parse_args("Booting kernel", static_command_line, __start___param,
 518                   __stop___param - __start___param,
 519                   -1, -1, &unknown_bootoption);
 520
 521        jump_label_init();
 522
 523        /*
 524         * These use large bootmem allocations and must precede
 525         * kmem_cache_init()
 526         */
 527        setup_log_buf(0);
 528        pidhash_init();
 529        vfs_caches_init_early();
 530        sort_main_extable();
 531        trap_init();
 532        mm_init();
 533
 534        /*
 535         * Set up the scheduler prior starting any interrupts (such as the
 536         * timer interrupt). Full topology setup happens at smp_init()
 537         * time - but meanwhile we still have a functioning scheduler.
 538         */
 539        sched_init();
 540        /*
 541         * Disable preemption - early bootup scheduling is extremely
 542         * fragile until we cpu_idle() for the first time.
 543         */
 544        preempt_disable();
 545        if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
 546                local_irq_disable();
 547        idr_init_cache();
 548        rcu_init();
 549        tick_nohz_init();
 550        context_tracking_init();
 551        radix_tree_init();
 552        /* init some links before init_ISA_irqs() */
 553        early_irq_init();
 554        init_IRQ();
 555        tick_init();
 556        init_timers();
 557        hrtimers_init();
 558        softirq_init();
 559        timekeeping_init();
 560        time_init();
 561        sched_clock_postinit();
 562        perf_event_init();
 563        profile_init();
 564        call_function_init();
 565        WARN(!irqs_disabled(), "Interrupts were enabled early\n");
 566        early_boot_irqs_disabled = false;
 567        local_irq_enable();
 568
 569        kmem_cache_init_late();
 570
 571        /*
 572         * HACK ALERT! This is early. We're enabling the console before
 573         * we've done PCI setups etc, and console_init() must be aware of
 574         * this. But we do want output early, in case something goes wrong.
 575         */
 576        console_init();
 577        if (panic_later)
 578                panic(panic_later, panic_param);
 579
 580        lockdep_info();
 581
 582        /*
 583         * Need to run this when irqs are enabled, because it wants
 584         * to self-test [hard/soft]-irqs on/off lock inversion bugs
 585         * too:
 586         */
 587        locking_selftest();
 588
 589#ifdef CONFIG_BLK_DEV_INITRD
 590        if (initrd_start && !initrd_below_start_ok &&
 591            page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
 592                pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
 593                    page_to_pfn(virt_to_page((void *)initrd_start)),
 594                    min_low_pfn);
 595                initrd_start = 0;
 596        }
 597#endif
 598        page_cgroup_init();
 599        debug_objects_mem_init();
 600        kmemleak_init();
 601        setup_per_cpu_pageset();
 602        numa_policy_init();
 603        if (late_time_init)
 604                late_time_init();
 605        sched_clock_init();
 606        calibrate_delay();
 607        pidmap_init();
 608        anon_vma_init();
 609#ifdef CONFIG_X86
 610        if (efi_enabled(EFI_RUNTIME_SERVICES))
 611                efi_enter_virtual_mode();
 612#endif
 613        thread_info_cache_init();
 614        cred_init();
 615        fork_init(totalram_pages);
 616        proc_caches_init();
 617        buffer_init();
 618        key_init();
 619        security_init();
 620        dbg_late_init();
 621        vfs_caches_init(totalram_pages);
 622        signals_init();
 623        /* rootfs populating might need page-writeback */
 624        page_writeback_init();
 625#ifdef CONFIG_PROC_FS
 626        proc_root_init();
 627#endif
 628        cgroup_init();
 629        cpuset_init();
 630        taskstats_init_early();
 631        delayacct_init();
 632
 633        check_bugs();
 634
 635        acpi_early_init(); /* before LAPIC and SMP init */
 636        sfi_init_late();
 637
 638        if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 639                efi_late_init();
 640                efi_free_boot_services();
 641        }
 642
 643        ftrace_init();
 644
 645        /* Do the rest non-__init'ed, we're now alive */
 646        rest_init();
 647}
 648
 649/* Call all constructor functions linked into the kernel. */
 650static void __init do_ctors(void)
 651{
 652#ifdef CONFIG_CONSTRUCTORS
 653        ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
 654
 655        for (; fn < (ctor_fn_t *) __ctors_end; fn++)
 656                (*fn)();
 657#endif
 658}
 659
 660bool initcall_debug;
 661core_param(initcall_debug, initcall_debug, bool, 0644);
 662
 663static int __init_or_module do_one_initcall_debug(initcall_t fn)
 664{
 665        ktime_t calltime, delta, rettime;
 666        unsigned long long duration;
 667        int ret;
 668
 669        pr_debug("calling  %pF @ %i\n", fn, task_pid_nr(current));
 670        calltime = ktime_get();
 671        ret = fn();
 672        rettime = ktime_get();
 673        delta = ktime_sub(rettime, calltime);
 674        duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 675        pr_debug("initcall %pF returned %d after %lld usecs\n",
 676                 fn, ret, duration);
 677
 678        return ret;
 679}
 680
 681int __init_or_module do_one_initcall(initcall_t fn)
 682{
 683        int count = preempt_count();
 684        int ret;
 685        char msgbuf[64];
 686
 687        if (initcall_debug)
 688                ret = do_one_initcall_debug(fn);
 689        else
 690                ret = fn();
 691
 692        msgbuf[0] = 0;
 693
 694        if (preempt_count() != count) {
 695                sprintf(msgbuf, "preemption imbalance ");
 696                preempt_count() = count;
 697        }
 698        if (irqs_disabled()) {
 699                strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
 700                local_irq_enable();
 701        }
 702        WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
 703
 704        return ret;
 705}
 706
 707
 708extern initcall_t __initcall_start[];
 709extern initcall_t __initcall0_start[];
 710extern initcall_t __initcall1_start[];
 711extern initcall_t __initcall2_start[];
 712extern initcall_t __initcall3_start[];
 713extern initcall_t __initcall4_start[];
 714extern initcall_t __initcall5_start[];
 715extern initcall_t __initcall6_start[];
 716extern initcall_t __initcall7_start[];
 717extern initcall_t __initcall_end[];
 718
 719static initcall_t *initcall_levels[] __initdata = {
 720        __initcall0_start,
 721        __initcall1_start,
 722        __initcall2_start,
 723        __initcall3_start,
 724        __initcall4_start,
 725        __initcall5_start,
 726        __initcall6_start,
 727        __initcall7_start,
 728        __initcall_end,
 729};
 730
 731/* Keep these in sync with initcalls in include/linux/init.h */
 732static char *initcall_level_names[] __initdata = {
 733        "early",
 734        "core",
 735        "postcore",
 736        "arch",
 737        "subsys",
 738        "fs",
 739        "device",
 740        "late",
 741};
 742
 743static void __init do_initcall_level(int level)
 744{
 745        extern const struct kernel_param __start___param[], __stop___param[];
 746        initcall_t *fn;
 747
 748        strcpy(static_command_line, saved_command_line);
 749        parse_args(initcall_level_names[level],
 750                   static_command_line, __start___param,
 751                   __stop___param - __start___param,
 752                   level, level,
 753                   &repair_env_string);
 754
 755        for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
 756                do_one_initcall(*fn);
 757}
 758
 759static void __init do_initcalls(void)
 760{
 761        int level;
 762
 763        for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
 764                do_initcall_level(level);
 765}
 766
 767/*
 768 * Ok, the machine is now initialized. None of the devices
 769 * have been touched yet, but the CPU subsystem is up and
 770 * running, and memory and process management works.
 771 *
 772 * Now we can finally start doing some real work..
 773 */
 774static void __init do_basic_setup(void)
 775{
 776        cpuset_init_smp();
 777        usermodehelper_init();
 778        shmem_init();
 779        driver_init();
 780        init_irq_proc();
 781        do_ctors();
 782        usermodehelper_enable();
 783        do_initcalls();
 784        random_int_secret_init();
 785}
 786
 787static void __init do_pre_smp_initcalls(void)
 788{
 789        initcall_t *fn;
 790
 791        for (fn = __initcall_start; fn < __initcall0_start; fn++)
 792                do_one_initcall(*fn);
 793}
 794
 795/*
 796 * This function requests modules which should be loaded by default and is
 797 * called twice right after initrd is mounted and right before init is
 798 * exec'd.  If such modules are on either initrd or rootfs, they will be
 799 * loaded before control is passed to userland.
 800 */
 801void __init load_default_modules(void)
 802{
 803        load_default_elevator_module();
 804}
 805
 806static int run_init_process(const char *init_filename)
 807{
 808        argv_init[0] = init_filename;
 809        return do_execve(init_filename,
 810                (const char __user *const __user *)argv_init,
 811                (const char __user *const __user *)envp_init);
 812}
 813
 814static noinline void __init kernel_init_freeable(void);
 815
 816static int __ref kernel_init(void *unused)
 817{
 818        kernel_init_freeable();
 819        /* need to finish all async __init code before freeing the memory */
 820        async_synchronize_full();
 821        free_initmem();
 822        mark_rodata_ro();
 823        system_state = SYSTEM_RUNNING;
 824        numa_default_policy();
 825
 826        flush_delayed_fput();
 827
 828        if (ramdisk_execute_command) {
 829                if (!run_init_process(ramdisk_execute_command))
 830                        return 0;
 831                pr_err("Failed to execute %s\n", ramdisk_execute_command);
 832        }
 833
 834        /*
 835         * We try each of these until one succeeds.
 836         *
 837         * The Bourne shell can be used instead of init if we are
 838         * trying to recover a really broken machine.
 839         */
 840        if (execute_command) {
 841                if (!run_init_process(execute_command))
 842                        return 0;
 843                pr_err("Failed to execute %s.  Attempting defaults...\n",
 844                        execute_command);
 845        }
 846        if (!run_init_process("/sbin/init") ||
 847            !run_init_process("/etc/init") ||
 848            !run_init_process("/bin/init") ||
 849            !run_init_process("/bin/sh"))
 850                return 0;
 851
 852        panic("No init found.  Try passing init= option to kernel. "
 853              "See Linux Documentation/init.txt for guidance.");
 854}
 855
 856static noinline void __init kernel_init_freeable(void)
 857{
 858        /*
 859         * Wait until kthreadd is all set-up.
 860         */
 861        wait_for_completion(&kthreadd_done);
 862
 863        /* Now the scheduler is fully set up and can do blocking allocations */
 864        gfp_allowed_mask = __GFP_BITS_MASK;
 865
 866        /*
 867         * init can allocate pages on any node
 868         */
 869        set_mems_allowed(node_states[N_MEMORY]);
 870        /*
 871         * init can run on any cpu.
 872         */
 873        set_cpus_allowed_ptr(current, cpu_all_mask);
 874
 875        cad_pid = task_pid(current);
 876
 877        smp_prepare_cpus(setup_max_cpus);
 878
 879        do_pre_smp_initcalls();
 880        lockup_detector_init();
 881
 882        smp_init();
 883        sched_init_smp();
 884
 885        do_basic_setup();
 886
 887        /* Open the /dev/console on the rootfs, this should never fail */
 888        if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
 889                pr_err("Warning: unable to open an initial console.\n");
 890
 891        (void) sys_dup(0);
 892        (void) sys_dup(0);
 893        /*
 894         * check if there is an early userspace init.  If yes, let it do all
 895         * the work
 896         */
 897
 898        if (!ramdisk_execute_command)
 899                ramdisk_execute_command = "/init";
 900
 901        if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
 902                ramdisk_execute_command = NULL;
 903                prepare_namespace();
 904        }
 905
 906        /*
 907         * Ok, we have completed the initial bootup, and
 908         * we're essentially up and running. Get rid of the
 909         * initmem segments and start the user-mode stuff..
 910         */
 911
 912        /* rootfs is available now, try loading default modules */
 913        load_default_modules();
 914}
 915
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